Merge pull request #4554 from mwichmann/move-env-checker

[scons.git] / CHANGES.txt

                 SCons - a software construction tool

                            Change Log

NOTE: The 4.0.0 release of SCons dropped Python 2.7 support. Use 3.1.2 if
  Python 2.7 support is required (but note old SCons releases are unsupported).
NOTE: Since SCons 4.3.0, Python 3.6.0 or above is required.
NOTE: Python 3.6 support is deprecated and will be dropped in a future reease.
  python.org no longer supports 3.6 or 3.7, and will drop 3.8 in Oct. 2024.

RELEASE  VERSION/DATE TO BE FILLED IN LATER

  From Thaddeus Crews:
    - GetSConsVersion() to grab the latest SCons version without needing to
      access SCons internals.
    - Migrate setup.cfg logic to pyproject.toml; remove setup.cfg.
    - Update .gitattributes to match .editorconfig; enforce eol settings.

  From Raymond Li:
    - Fix issue #3935: OSErrors are now no longer hidden during execution of
      Actions. All exceptions during the execution of an Action are now
      returned by value rather than by raising an exception, for more
      consistent behavior.
      NOTE: With this change, user created Actions should now catch and handle
      expected exceptions (whereas previously many of these were silently
      caught and suppressed by the SCons Action exection code).

  From Ryan Carsten Schmidt:
    - Teach ParseFlags to put a --stdlib=libname argument into CXXFLAGS.
      If placed in CCFLAGS (the default location), it could be fed to the
      C compiler (gcc, clang) where it is not applicable and causes a
      warning message.

  From Mats Wichmann:
    - Updated Value Node docs and tests.
    - Python 3.13 compat: re.sub deprecated count, flags as positional args,
      caused update-release-info test to fail.
    - Dump() with json format selected now recognizes additional compound types
      (UserDict and UserList), which improves the detail of the display.
      json output is also sorted, to match the default display.
    - Python 3.13 (alpha) changes the behavior of isabs() on Windows. Adjust
      SCons usage of in NodeInfo classes to match.  Fixes #4502, #4504.
    - Drop duplicated __getstate__ and __setstate__ methods in AliasNodeInfo,
      FileNodeInfo and ValueNodeInfo classes, as they are identical to the
      ones in parent NodeInfoBase and can just be inherited.
    - Update manpage for Tools, and for TOOL, which also gets a minor
      tweak for how it's handled (should be more accurate in a few situations).
    - Test framework now uses a subdirectory named "scons" below the base
      temporary directory. This gives something invariant to tell antivirus
      to ignore without having to exclude tmpdir itself. Fixes #4509.
    - MSVS "live" tests of project files adjusted to look for the generated
      executable with an exe sufffix
    - Documentation build now properly passes through skipping the PDF
      (and EPUB) builds of manpage and user guide; this can also be done
      manually if directly calling doc/man/SConstruct and doc/user/SConstruct
      by adding SKIP_PDF=1.  This should help with distro packaging of SCons,
      which now does not need "fop" and other tools to be set up in order to
      build pdf versions which are then ignored.
    - Add the ability to print a Variables object for debugging purposes
      (provides a __str__ method in the class).
    - Mark Python 3.6 support as deprecated.
    - Clean up Variables: more consistently call them variables (finish the
      old change from Options) in docstrings, etc.; some typing and other
      tweaks.  Update manpage and user guide for Variables usage.
    - Regularize internal usage of Python version strings and drop one
      old Python 2-only code block in a test.
    - scons-time tests now supply a "filter" argument to tarfile.extract
      to quiet a warning which was added in Python 3.13 beta 1.
    - Improved the conversion of a "foreign" exception from an action
      into BuildError by making sure our defaults get applied even in
      corner cases. Fixes #4530.
    - Restructured API docs build (Sphinx) so main module contents appear
      on a given page *before* the submodule docs, not after. Also
      tweaked the Util package doc build so it's structured more like the
      other packages (a missed part of the transition when it was split).
    - Updated manpage description of Command "builder" and function.
    - Framework for scons-time tests adjusted so a path with a long username
      Windows has squashed doesn't get re-expanded. Fixes a problem seen
      on GitHub Windows runner which uses a name "runneradmin".
    - SCons.Environment.is_valid_construction_var() now returns a boolean to
      match the convention that functions beginning with "is" have yes/no
      answers (previously returned either None or an re.match object).
      Now matches the annotation and docstring (which were prematurely
      updated in 4.6). All SCons usage except unit test was already fully
      consistent with a bool.
    - When a variable is added to a Variables object, it can now be flagged
      as "don't perform substitution" by setting the argument subst.
      This allows variables to contain characters which would otherwise
      cause expansion. Fixes #4241.
    - The test runner now recognizes the unittest module's return code of 5,
      which means no tests were run. SCons/Script/MainTests.py currently
      has no tests, so this particular error code is expected - should not
      cause runtest to give up with an "unknown error code".
    - Updated the notes about reproducible builds with SCons and the example.
    - The Clone() method now respects the variables argument (fixes #3590)
    - is_valid_construction_var() (not part of the public API) moved from
      SCons.Environment to SCons.Util to avoid the chance of import loops. Variables
      and Environment both use the routine and Environment() uses a Variables()
      object so better to move to a safer location.


RELEASE 4.7.0 -  Sun, 17 Mar 2024 17:22:20 -0700

  From Ataf Fazledin Ahamed:
    - Use of NotImplemented instead of NotImplementedError for special methods
      of _ListVariable class

  From Joseph Brill:
    - Fix issue #2755: the msvs tool no longer writes the OS environment SCONS_HOME
      value into the SCons environment when the SCONS_HOME variable already exists
      in the SCons environment.  Prior to this change, a valid user-defined SCons
      environment value for SCONS_HOME would be overwritten with the OS environment
      value of SCONS_HOME which could be None (i.e., undefined).
    - Update the windows registry keys for detection of Visual Studio 2015 Express
      ('14.0Exp'): the VS2015 registry key ('WDExpress') appears to be different
      than the registry key ('VCExpress') for earlier Visual Studio express
      versions.  The registry key value is relative to the installation root rather
      than the VC folder and requires additional path components during evaluation.
    - Fix the vs-6.0-exec.py test script: the msvs generated project is 'foo.dsp'
      and the command-line invocation of the Visual Studio development environment
      program was attempting to build 'test.dsp'.  The command-line invocation was
      changed to build 'foo.dsp'.
    - Update the msvs project generation test scripts: the msvs project execution
      tests could produce a "false positive" test result when the test executable is
      correctly built via the SConstruct env.Program() call and the command-line
      invocation of the Visual Studio development environment program fails.  The
      test passes due to the existence of the test executable from the initial
      build.  The tests were modified to delete the test executable, object file,
      and sconsign file prior to the command-line invocation of the VS development
      binary.
    - Method unlink_files was added to the TestCmd class that unlinks a list of
      files from a specified directory.  An attempt to unlink a file is made only
      when the file exists; otherwise, the file is ignored.
    - Fix issue #4320: add an optional argument list string to configure's CheckFunc
      method so that the generated function argument list matches the function's
      prototype when including a header file.

  From Thaddeus Crews:
    - Explicitly wrap non-serializable values in json dump
    - Implemented SCons.Util.sctyping as a safe means of hinting complex types. Currently
      only implemented for `Executor` as a proof-of-concept.

  From William Deegan:
    - Fix sphinx config to handle SCons versions with post such as: 4.6.0.post1

  From Michał Górny:
    - Remove unnecessary dependencies on pypi packages from setup.cfg

  From Sten Grüner:
    - Fix of the --debug=sconscript option to return exist statements when using return
      statement with stop flag enabled

  From Prabhu S. Khalsa:
    - Fix typo in user documentation (issue #4458)

  From Andrew Morrow:
    - The NewParallel scheduler is now the default, the `tm_v2` flag is removed,
      and the old scheduler is opt-in under `--experimental=legacy_sched`. Additionally,
      the new scheduler is now used for -j1 builds as well.
    - A python interpreter with support for the `threading` package is now required,
      and this is enforced on startup. SCons currently sets its minimum supported
      Python to 3.6, and it was not until Python 3.7 where `threading` became
      default supported. In practice, we expect most real world Python 3.6 deployments
      will have `threading` support enabled, so this will not be an issue.
    - CacheDir writes no longer happen within the taskmaster critical section,
      and therefore can run in parallel with both other CacheDir writes and the
      taskmaster DAG walk.
    - The NewParallel scheduler now only adds threads as new work requiring execution
      is discovered, up to the limit set by -j. This should reduce resource utilization
      when the achievable parallelism in the DAG is less than the -j limit.

  From Mats Wichmann:
    - Add support for Python 3.13 (as of alpha 2). So far only affects
      expected bytecodes in ActionTests.py.
    - sconsign cleanup - remove some dead code, minor manpage tweaks.
    - Be more cautious about encodings fetching command output on Windows.
      Problem occurs in piped-spawn scenario, used by Configure tests.
      Fixes #3529.
    - Clarify/fix documentation of Scanners in User Guide and Manpage.
      Fixes #4468.
    - Fix bad typing in Action.py: process() and strfunction().
    - Add Pseudo() to global functions, had been omitted. Fixes #4474.
    - Improve handling of file data that SCons itself processes - try
      harder to decode non-UTF-8 text. SCons.Util.to_Text now exists
      to convert a byte stream, such as "raw" file data.  Fixes #3569, #4462.
      The Pseudo manpage entry was updated to provide more clarity.
    - Clarify how SCons finds the project top directory, and what that is used for.
    - The internal routine which implements the PyPackageDir function
      would fail with an exception if called with a module which is
      not found.  It will now return None.  Updated manpage entry and
      docstring..
    - Doc update: standardized on the use of a new entity &MSVC; to
      describe the Microsoft C++ compiler. Update the version table slightly.
      Amplified the usage of MSVC_VERSION.
    - Improve SharedLibrary docs a bit.
    - More consistent use of &Python; in the manpage.  A few links added.
      A warning about overwriting env['ENV'] and one about Configure
      checks possibly not running in in no-exec mode also added.
    - Update warnings module: adds docstrings, drop three unused warnings
      (DeprecatedSourceCodeWarning, TaskmasterNeedsExecuteWarning,
      DeprecatedMissingSConscriptWarning) add two warnings to manpage
      (cache-cleanup-error, future-reserved-variable), improve unittest, tweak
      Sphinx build.
    - Add locking around creation of CacheDir config file. Fixes #4489.
    - Clarify MergeFlags usage of a dict argument.
    - SCons documentation build can now be controlled through SKIP_DOC
      variable - rather than just true/false can now specify
      skip none, skip all, skip pdf docs, skip api docs.


RELEASE 4.6.0 -  Sun, 19 Nov 2023 17:22:20 -0700

  From Max Bachmann:
    - Add missing directories to searched paths for mingw installs

  From Joseph Brill:
    - Fix issue #4312: the cached installed msvc list had an indirect dependency
      on the target architecture in the environment dictionary.  The first call
      to construct the installed msvc list now forces the target architecture to be
      undefined, constructs the installed msvc list, and then restores the original
      target architecture.
      Note: an indirect dependency on the VSWHERE construction variable in the
      environment remains.
    - Fix issue #4312: explicitly guard against an empty regular expression list
      when msvc is not installed.
    - When trying to find a valid msvc batch file, check that the compiler executable
      (cl.exe) exists for VS6 to VS2015 to avoid executing the msvc batch file.  Always
      check that the compiler executable is found on the msvc script environment path
      after running the msvc batch file.  Only use the sdk batch files when all of the
      msvc script host/target combinations have been exhausted and a valid script was
      not found.
    - Add ARM64 host configurations for windows and msvc.
      Note: VS2013 and earlier has not been tested on ARM64.
    - If necessary, automatically define VSCMD_SKIP_SENDTELEMETRY for VS2019 and later
      on ARM64 hosts when using an arm32 build of python to prevent a powershell dll
      not found error pop-up window.
    - Fix an issue where test SConfTests.py would fail when mscommon debugging
      was enabled.  The mscommon debug filter class registered with the logging
      module was refactored.
    - Add arm64 to the MSVS supported architectures list for VS2017 and later to be
      consistent with the current documentation of MSVS_ARCH.
    - Fix an issue with an unhandled MissingConfiguration exception due to an msvc
      registry query that returns a path that does not exist.  Multiple invocation
      paths were not prepared to handle the MissingConfiguration exception.  The
      MissingConfiguration exception type was removed.
    - The MSCommon module import was changed from a relative import to a top-level
      absolute import in the following Microsoft tools: midl, mslib, mslink, mssdk, msvc,
      msvs. Moving any of these tools that used relative imports to the scons site tools
      folder would fail on import (i.e., the relative import paths become invalid when
      moved).
    - The detection of the msvc compiler executable (cl.exe) has been modified:
        * The host os environment path is no longer evaluated for the existence of the
          msvc compiler executable when searching the detection dictionary.
        * The existence of the msvc compiler executable is checked in the detection
          dictionary and the scons ENV path before the detection dictionary is merged
          into the scons ENV.
        * Different warnings are produced when the msvc compiler is not detected in the
          detection dictionary based on whether or not an msvc compiler was detected in
          the scons ENV path (i.e., a msvc compiler executable already exists in the
          user's ENV path prior to detection).
        * The warning message issued when a msvc compiler executable is not found in the
          detection dictionary was modified by adding the word "requested":
            Old warning: "Could not find MSVC compiler 'cl'."
            New warning: "Could not find requested MSVC compiler 'cl'.".
        * An additonal sentence is appended to the warning message issued when an msvc
          compiler executable is not found in the msvc detection dictionary and is found
          in the user's ENV path prior to detection:
            " A 'cl' was found on the scons ENV path which may be erroneous."

  From Vitaly Cheptsov:
    - Fix race condition in `Mkdir` which can happen when two `SConscript`
      are processed simultaneously by two separate build commands.

  From William Deegan:
    - The --debug flag now has a 'json' option which will write information
      generated by --debug={count, memory, time, action-timestamps} and about
      the build.
    - Obsoleted YACCVCGFILESUFFIX, being replaced by YACC_GRAPH_FILE_SUFFIX.
      If YACC_GRAPH_FILE_SUFFIX is not set, it will respect YACCVCGFILESUFFIX.

  From Sten Grüner
    - The newly added --debug=sconscript option (new) will output notices when
      entering an exiting each SConscript as they are processed.

  From Philipp Maierhöfer:
    - Fix gfortran tool initialization. Defaults to using binary named gfortran
      as would be expected, and properly set's SHFORTRAN flags to include -fPIC
      where previously it was only doing so for the other fortran versions (F77,..)

  From Jonathon Reinhart:
    - Fix another instance of `int main()` in CheckLib() causing failures
      when using -Wstrict-prototypes.

  From Mats Wichmann
    - C scanner's dictifyCPPDEFINES routine did not understand the possible
      combinations of CPPDEFINES - not aware of a "name=value" string either
      embedded in a sequence, or by itself.  The conditional C scanner thus
      did not always properly apply the defines. The regular C scanner does
      not use these, so was not affected.  [fixes #4193]
    - Minor cleanup for ValidateOptions - docs and docstring tweaked,
      add missed versionadded indicator.
    - Added some typing annotations generated by a tool, to eliminate manual
      work in future on things which are safe for the tool to produce.
      Then manually fixed up some things related to bool that the tool did
      not handly ideally. For example, simple functions which just did
      "return 1" were interpreted by the tool as returning int, when bool
      was really the intent.  Functions/methods named like "is_*", "has_*",
      "exists" are now pretty consistently marked as "-> bool".
    - Simplify some code due to pylint observation: "C2801: Unnecessarily
      calls dunder method __call__. Invoke instance directly."
    - Python 3.9 dropped the alias base64.decodestring, deprecated since 3.1.
      Only used in msvs.py. Use base64.decodebytes instead.
    - When debugging (--debug=pdb), the filenames SConstruct and SConscript
      are now recognized when manipulating breakpoints. Previously,
      only a full pathname to an sconscript file worked, as pdb requires
      a .py extension to open a file that is not an absolute path.
    - SCons test runner now uses pathlib to normalize and compare paths
      to test files.
    - D compilers : added support for generation of .di interface files.
      New variables DI_FILE_DIR, DI_FILE_DIR_PREFIX, DI_FILE_DIR_SUFFIX,
      DI_FILE_SUFFIX.
    - Fixed: when using the mingw tool, if an msys2 Python is used (os.sep
      is '/' rather than the Windows default '\'), certain Configure checks
      could fail due to the construction of the path to run the compiled check.
    - Added effort to find mingw if it comes from Chocolatey install of msys2.
    - Minor doc fixes: signature of Alias() now matches implementation
      to avoid problem if kwargs used; case of Alias with no targets is
      mentioned in text (was already shown in example); now mention that
      Action([item]) does not return a ListAction - previously implied
      that if arg was a list, a ListAction was *always* returned; mention
      default Decider and sort the names of available decider functions,
      and add a version marking.  Minor fiddling with Alias.py docstrings.
    - Python 3.12 support: new bytecodes for ActionTests.py, adapt to
      changes to pathlib module in runtest.py (PosixPath no longer
      converts slashes if given a Windows-style path). Also switch to
      using `subTest` in `ActionTests`, so that we can see all 21 fails
      due to bytecode changes (previously testcases aborted on the first
      assert fail so we only saw seven), and use unittest asserts to
      simplify complex printing stanzas.
    - Added copyright headers to files in test/ that didn't have them.
    - Drop three unused methods from the Environment Base class:
      get_src_sig_type and get_tgt_sig_type, as well as "private"
      _changed_source. These were orphaned when the long-deprecated
      Source Signatures and Target Signatures were removed, these were
      missed at that time.
    - Remove dead code: some mocked classes in unit tests had methods
      which have been removed from the Node class they're mocking,
      there's no need to shadow those any more as there are no callers.
      The methods are depends_on (base functionality removed in 2005)
      and is_pseudeo_derived (base functionality removed in 2006). There
      may well be more!
    - Added pass_test() call to test/MSVC/MSVC_BATCH-spaces-targetdir.py.
      It looked it was missing a more detailed check, but it should be
      sufficient just to check the build worked. Renamed the fixture
      dir to follow naming convention in test/MSVC overall, and added
      a sconstest.skip file, also to follow convention.
    - Marked some scanner methods as @staticmethod.
    - Class ActionBase is now an abstract base class to more accurately
      reflect its usage. Derived _ActionAction inherits the ABC, so it
      now declares (actually raises NotImplementedError) two methods it
      doesn't use so it can be instantiated by unittests and others.
    - The yacc tool now understands the bison behavior of --header,
      --defines and --graph being called without option-argument as being
      synonyms for -d (first two) and -g. -H also recognized as a synonym
      for -d.  Default value for $YACC_GRAPH_FILE_SUFFIX changed to '.gv'
      to match current bison default (since bison 3.8).  Set this variable
      to '.dot' if using byacc. The graph file name (-g) is now generated
      relative to the requested target file name, not to the source file
      name, to match actual current behavior (only affects if target
      explicitly requested with a different base name
      than source).  Docs updated.  Fixes #4326 and #4327.
    - Cleaned up dblite module (checker warnings, etc.).
    - Some cleanup in the FortranCommon tool.
    - Rewrite the internal _subproc routine - a new scons_subproc_run() now
      makes use of Python's subprocess.run in a more natural way, getting
      around some of the issues with attempted context manager use, fetching
      output, etc. - we let the subprocess module do the hard work,
      since it's well debugged and supported.  _subproc is no longer
      called by internal code, but remains in place in case there are builds
      which call to it (even though it was never "published API").
    - Changed the message about scons -H to clarify it shows built-in options.
    - Improve CacheDir() Documentation.
    - Release-building setup tweaked. (most of) the targets listed in
      SCons' own "scons --help" now work again.
    - Fix platform unit test on Windows for Py 3.12+. Fixes #4376.
    - More tweaking of test framework overview (which is duplicated onto
      the website, but not in the regular documentation section).
    - Extend range of recognized Java versions to 20.
    - Builder calls now accept PathLike objects in source lists. Fixes #4398.
    - The Help() function now takes an additional keyword argument
      keep_local: when starting to build a help message, you can now
      retain help from AddOption calls, but omit help for SCons' own
      command-line options with "Help(newtext, append=True, local_only=True)".
    - A little more code "modernization", done via "pypgrade" tool set
      to "3.6 and above" setting.
    - Finish the change to make calling SConscript() with a nonexistent
      file an error. It has issued a warning since 3.0, with "warn instead
      of fail" deprecated since 3.1.  Fixes #3958.
    - Minor (non-functional) cleanup of some tests, particuarly test/MSVC.
    - Added more error handling while reading msvc config cache.
      (Enabled/specified by SCONS_CACHE_MSVC_CONFIG).
      The existing cache will be discarded if there's a decode error reading it.
      It's possible there's a race condition creating this issue in certain CI
      builds.  Also add a simple filesystem-based locking protocol to try to
      avoid the problem occuring.
    - Update the first two chapters on building with SCons in the User Guide.
    - Update docs on Export/Import - make sure mutable/immutable status has
      been mentioned.
    - Some cleanup to the Util package, including renaming SCons.Util.types
      to SCons.Util.sctypes to avoid any possible confusion with the
      Python stdlib types module.
    - TeX tests: skip tests that use makeindex or epstopdf not installed, or
      if `kpsewhich glossaries.sty` fails.
    - Added a .note.GNU-stack section to the test assembler files to
      avoid the GNU linker issuing warnings for its absence.
    - Eliminate more http: references (mostly in comments/docstrings where
      they really weren't harmful). A few links labeled dead with no alt.
    - Add JDK 21 LTS support
    - Add a LIBLITERALPREFIX variable which can be set to the linker's
      prefix for considering a library argument unmodified (e.g. for the
      GNU linker, the ':' in '-l:libfoo.a'). Fixes Github issue #3951.
    - Update PCH builder docs with some usage notes.

RELEASE 4.5.2 -  Sun, 21 Mar 2023 14:08:29 -0700

  From Michał Górny:
    - Remove the redundant `wheel` dependency from `pyproject.toml`,
      as it is added automatically by the setuptools PEP517 backend.

  From Mats Wichmann
    -  Fix a problem (#4321) in 4.5.0/4.5.1 where ParseConfig could cause an
       exception in MergeFlags when the result would be to add preprocessor
       defines to existing CPPDEFINES. The following code illustrates the
       circumstances that could trigger this:
          env=Environment(CPPDEFINES=['a'])
          env.Append(CPPDEFINES=['b'])
          env.MergeFlags({'CPPDEFINES': 'c'})


RELEASE 4.5.1 -  Mon, 06 Mar 2023 14:08:29 -0700

  From Mats Wichmann
    - Fix a problem in 4.5.0 where using something like the following code
      will cause a Clone()'d environment to share the CPPDEFINES with the
      original Environment() which was cloned. Causing leakage of changes
      to CPPDEFINES when they should be completely independent after the Clone.
          env=Environment(CPPDEFINES=['a'])
          env.Append(CPPDEFINES=['b']) (or AppendUnique,Prepend,PrependUnique)
          env1=env.Clone()
          env1.Append(CPPDEFINES=['c']) (or any other modification, but not overwriting CPPDEFINES
      Now env['CPPDEFINES'] will contain 'c' when it should not.


RELEASE 4.5.0 -  Sun, 05 Mar 2023 14:08:29 -0700

  From Anatoli Babenia:
    - Do not initialize DefaultEnvironment when calling EnsureSConsVersion(),
      EnsurePythonVersion(), Exit(), GetLaunchDir() and SConscriptChdir().
    - Remove unused private method SConsEnvironment._exceeds_version().

  From William Deegan:
    - Added ValidateOptions() which will check that all command line options are in either
      those specified by SCons itself, or by AddOption() in SConstruct/SConscript.  It should
      not be called until all AddOption() calls are completed. Resolves Issue #4187
    - Refactored SCons/Taskmaster into a package. Moved SCons/Jobs.py into that package.
      NOTE: If you hook into SCons.Jobs, you'll have to change that to use SCons.Taskmaster.Jobs
    - Changed the Taskmaster trace logic to use python's logging module. The output formatting
      should remain (mostly) the same. Minor update to unittest for this to adjust for 1 less newline.
    - Migrated logging logic for --taskmastertrace to use Python's logging module. Added logging
      to NewParallel Job class (Andrew Morrow's new parallel job implementation)
    - Ninja: Fix execution environment sanitation for launching ninja. Previously if you set an
      execution environment variable set to a python list it would crash. Now it
      will create a string joining the list with os.pathsep
    - Move execution environment sanitation from Action._subproc() to
      SCons.Util.sanitize_shell_env(ENV)
    - Moved rpm and debian directories under packaging
    - Added logic to help packagers enable reproducible builds into packaging/etc/. Please
      read packaging/etc/README.txt if you are interested.
    - Added --experimental=tm_v2, which enables Andrew Morrow's new NewParallel Job implementation.
      This should scale much better for highly parallel builds. You can also enable this via SetOption().
    - Fixed command line argument --diskcheck: previously a value of 'none' was ignored.
      SetOption('diskcheck','none') is unaffected, as it did not have the problem.
    - Added overrides argument to SCons.Subst.scons_subst(), subst_list(), subst(), and Action's process(),
      strfunction(). This allows passing a dictionary of envvars to override when evaluating subst()'d strings/lists
    - Fixed Issue #4275 - when outputting compilation db and TEMPFILE was in use, the compilation db would have
      command lines using the generated tempfile for long command lines, instead of the full command line for
      the compilation step for the source/target pair.
    - Renamed the qt tools to qt3 since the logic in that tool is only for QT version 3.  Renamed all env vars
      which affect qt3 from QT_ to QT3_.  If you are still using SCons to build QT 3 code, you'll need to update
      your SConscripts.  Note that using 'qt' tool has been deprecated for some time.

  From David H:
    - Added JAVAPROCESSORPATH construction variable which populates -processorpath.
    - Updated JavaScanner to scan JAVAPROCESSORPATH.

  From Nickolai Korshunov
    - Added FILE_ENCODING, to allow explicitly setting the text encoding for files
      written by the Textfile() and Substfile() builders. If not specified, Textfile() and Substfile() builders
      will write files as UTF-8. Fixed Issue #4302.

  From Dan Mezhiborsky:
    - Add newline to end of compilation db (compile_commands.json).

  From Daniel Moody:
    - Added error message to handle the case when SCons attempts to retrieve all the targets
      for a specified builder from the CacheDir, fails to do so, and then runs into an error
      when deleting the files which were retrieved. Previously if this happened there was no
      errors or warnings.
    - Fix issue #2757, where Configure checks that perform a check which reads a modified source
      (including program, source or header file(s)) would incorrectly mark that file "up to date" so the
      actual build would not see the file as modified. Leading to incorrect incremental builds.
      Now configure checks now clear node info for non conftest nodes, so they will be re-evaluated for
      the real taskmaster run when the build commences.

  From Andrew Morrow
    - Avoid returning UniqueList for `children` and other `Executor` APIs. This type
      iterates more slowly than the builtin types. Also simplify uniquer_hashables to
      use an faster implementation under the assumption of ordered dictionaries.

  From Ryan Saunders:
    - Fixed runtest.py failure on Windows caused by excessive escaping of the path to python.exe.

  From Lukas Schrangl:
    - Run LaTeX after biber/bibtex only if necessary

  From Flaviu Tamas:
    - Added -fsanitize support to ParseFlags().  This will propagate to CCFLAGS and LINKFLAGS.

  From Mats Wichmann:
    - A list argument as the source to the Copy() action function is now
      correctly handled by converting elements to string. Copy errors out
      if asked to copy a list to an existing non-directory destination.
      Both the implementation and the strfunction which prints the progress
      message were adjusted. Fixes #3009.
    - doc: EnsureSConsVersion, EnsurePythonVersion, Exit, GetLaunchDir and
      SConscriptChdir are now listed as Global functions only; the
      Environment versions still work but are not documented.
    - The Java scanner processing of JAVACLASSPATH for dependencies was
      changed to split on os.pathsep instead of space, to match usage of
      passing a path string like "xxx:yyy:zzz". This is not portable -
      passing a POSIX-style path string (with ':') won't work on Windows
      (';') - which is now documented with a hint to use a list instead
      to be portable. Splitting on space broke paths with embedded spaces.
      Fixes #4243.
    - Cleanup: make sure BoolVariable usage in tests and examples uses Python
      boolean values instead of 0/1.
    - Stop telling people to run "python setup.py install" in the User Guide.
      Adds new content on using virtualenvs to be able to have multiple
      different SCons versions available on one system.
    - Added the "DefaultEnvironment(tools=[])" stanza to a number of tests
      that are known to be particularly slow.  It's still just a tiny
      speedup, but the Windows CI had been occasionally timing out,
      so maybe this helps a bit.
    - Remove an extra existence check in one ninja test that caused it
      to be skipped on some otherwise-valid Windows installations.
    - test framework tests now pass on Linux and Windows (the latter can
      still run into problems on some configurations), and automated
      tests are now run on changes in this area so future problems can
      be spotted.
    - The single-file Util module was split into a package with a few
      functional areas getting their own files - Util.py had grown to
      over 2100 lines.
    - Add a zipapp package of scons-local: can use SCons from a local
      file which does not need unpacking.
    - Additional explanations for MSVSProject and MSVSSolution builders.
    - Fix a problem (present in 4.4.0 only) where a Java inner class could
      not be cached because the emitted filename contained a '$' and when
      looked up through a node ended up generating a Python SyntaxError
      because it was passed through scons_subst().
    - Have the gfortran tool do a better job of honoring user preferences
      for the dialect tools (F77, F90, F03 and F09, as well as the shared-library
      equivalents SHF77,  SHF90, SHF03, SHF09). Previously these were
      unconditionally overwritten to 'gfortran'; the change should be more
      in line with expectations of how these variables should work.
      Also cleaned a few Fortran tests - test behavior does not change.
    - Updated MSVC documentation - adds "version added" annotations on recently
      added construction variables and provides a version-mapping table.
    - Add Python 3.12 support, and indicate 3.11/3.12 support in package.
      3.12 is in alpha for this SCons release, the bytecode sequences
      embedded in SCons/ActionTests.py may need to change later, but
      based on what is known now, 3.12 itself should work with this release.
    - Add "append" keyword argument to Configure context's CheckLib and
      CheckLibWithHeader to control whether to append or prepend (issue #2767)
      Also added "unique" keyword, to control whether a library is added
      or not if it is already in the $LIBS construction var in the
      configure context. (issue #2768).
    - Completely refactored the CPPDEFINES logic in Append/AppendUnique/Prepend/PrependUnique
      This change fixes the following GH Issues:
      - GH Issue #3876 - Append() and AppendUnique() will handle CPPDEFINES the same
      - GH Issue #4254 - Make handling tuples in CPPDEFINES consistent.
      - We no longer sort the keys added to CPPDEFINES by their dictionary keys.
        We take advantage that their order is now stable based on insertion order
        in Python 3.5+
      - Added/modifed unit and system tests to verify these changes.


RELEASE 4.4.0 -  Sat, 30 Jul 2022 14:08:29 -0700

  From Joseph Brill:
    - Verify that a user specified msvc script (via MSVC_USE_SCRIPT) exists and raise an exception
      when the user specified msvc script does not exist.
    - Fix issue where if you only had mingw installed on a Windows system and no MSVC compiler, and
      did not explicitly request the mingw tool, mingw tool initialization would fail and set the
      default compiler to MSVC which wasn't installed, yielding broken build.
      Updated mingw tool so that the generate and exists methods use the same mingw search paths
      (issue #4134).
    - Update the debug output written to stdout for MSVC initialization which is enabled by setting
      SCONS_MSCOMMON_DEBUG=- to use the logging module. Also changed the debug output format
      written to stdout to include more information about the source for each message of MSVC
      initialization debugging output.  A single space was added before the message for all
      debugging output records written to stdout and to files.
    - Refactor the data definitions for msvc configurations to allow derived data structures to be
      constructed during initialization that removes the need for special case handling during
      runtime execution. Special case handling of host/target combinations is eliminated and
      replaced with pre-computed search lists that implicitly handle the differences between full
      versions and express versions of msvc. This fixes an issue where Express versions of the MSVC
      compiler were not detected due to differences in initial msvc detection and msvc batch file
      determination when configuring the build environment.  This could lead to build failures when
      only an MSVC Express instance is installed and the MSVC version is not explicitly specified
      (issue #2668 and issue #2697).
    - Added MSVC_USE_SETTINGS construction variable to pass a dictionary to configure the msvc compiler
      system environment as an alternative to bypassing Visual Studio autodetection entirely.
    - Added MSVC_SDK_VERSION construction variable which allows building with a specific Microsoft
      SDK version. This variable is used with the msvc batch file determined via autodetection subject
      to validation constraints.  Refer to the documentation for additional requirements and validation
      details.
    - Added MSVC_TOOLSET_VERSION construction variable which allows building with a specific toolset
      version. This variable is used with the msvc batch file determined via autodetection subject to
      validation constraints. This variable does not affect the autodetection and selection of msvc
      instances. The toolset version is applied after an msvc instance is selected. This could be the
      default version of msvc. Refer to the documentation for additional requirements and validation
      details.  Addresses issue #3265, issue #3664, and pull request #4149.
    - Added MSVC_SPECTRE_LIBS construction variable which allows building with spectre-mitigated
      Visual C++ libraries. This variable is used with the msvc batch file determined via autodetection
      subject to validation constraints. Refer to the documentation for additional requirements and
      validation details.
    - Added MSVC_SCRIPT_ARGS construction variable which specifies command line arguments that are
      passed to the msvc batch file determined via autodetection subject to validation constraints.
      Refer to the documentation for additional requirements and validation details.  Addresses
      enhancement issue #4106.
    - An exception is raised when MSVC_UWP_APP is enabled for Visual Studio 2013 and earlier.
      Previous behavior was to silently ignore MSVC_UWP_APP when enabled for Visual Studio 2013
      and earlier. Refer to the documentation for additional requirements and validation details.
      MSVC_UWP_APP was extended to accept True, False, and None in addition to '1' and '0'.
    - The imported system environment variable names for MSVC 7.0 and 6.0 have been changed to the
      names set by their respective installers.  Prior to this change, bypassing MSVC detection by
      specifying the MSVC 7.0 batch file directly would fail due to using an erroneous environment
      variable name.  Arguments are no longer passed to the MSVC 6.0 to 7.1 batch files as no
      arguments are required and could improve the effectiveness of the internal MSVC cache.
    - Propagate the OS and windir environment variables from the system environment to the msvc
      environment.  The OS and windir environment variables are used in the MSVC 6.0 batch file
      and the SDK 6.0-7.1 SetEnv.cmd batch files.  Inclusion of the OS and windir environment
      variables eliminates some partial paths and warnings generated by the MSVC 6.0 and SDK
      6.0-7.1 batch files when the variables are not defined.
      Note: Attempting to run the SDK 6.0-7.1 batch files directly via MSVC_USE_SCRIPT can lead to
            build failures and/or incomplete build environments.  The SDK 6.0-7.1 batch files
            require delayed expansion to be enabled which is currently not supported and is
            typically not enabled by default on the host system. The batch files may also require
            environment variables that are not included by default in the msvc environment.
    - Suppress issuing a warning when there are no installed Visual Studio instances for the default
      tools configuration (issue #2813).  When msvc is the default compiler because there are no
      compilers installed, a build may fail due to the cl.exe command not being recognized.  At
      present, there is no easy way to detect during msvc initialization if the default environment
      will be used later to build a program and/or library. There is no error/warning issued for the
      default tools as there are legitimate SCons uses that do not require a c compiler.
    - Added a global policy setting and an environment construction variable for specifying the
      action to be taken when an msvc request cannot be satisfied. The available options are "error",
      "exception", "warning", "warn", "ignore", and "suppress".  The global policy variable may be
      set and retrieved via the functions msvc_set_notfound_policy and msvc_get_notfound_policy,
      respectively.  These two methods may be imported from SCons.Tool.MSCommon. The environment
      construction variable is MSVC_NOTFOUND_POLICY.  When defined, the environment construction
      variable overrides the global policy setting for a given environment. When the active policy
      is "error" or "exception", an MSVCVersionNotFound exception is raised.  When the active policy
      is "warning" or "warn", a VisualCMissingWarning warning is issued and the constructed
      environment is likely incomplete. When the active policy is "ignore" or "suppress", no action
      is taken and the constructed environment is likely incomplete.  As implemented, the default
      global policy is "warning".  The ability to set the global policy via an SCons command-line
      option may be added in a future enhancement.
    - Added a global policy setting and an environment construction variable for specifying the
      action to be taken when msvc script errors are detected. The available options are "error",
      "exception", "warning", "warn", "ignore", and "suppress".  The global policy variable may be
      set and retrieved via the functions msvc_set_scripterror_policy and msvc_get_scripterror_policy,
      respectively.  These two methods may be imported from SCons.Tool.MSCommon. The environment
      construction variable is MSVC_SCRIPTERROR_POLICY.  When defined, the environment construction
      variable overrides the global policy setting for a given environment. When the active policy
      is "error" or "exception", an MSVCScriptExecutionError exception is raised when msvc batch file
      errors are detected.  When the active policy is "warning" or "warn", an MSVCScriptExecutionWarning
      warning is issued when msvc batch file errors are detected. When the active policy is "ignore" or
      "suppress", msvc batch error messages are suppressed.  As implemented, the default global policy
      is "ignore".  The ability to set the global policy via an SCons command-line option may be added
      in a future enhancement.
    - Added experimental function msvc_query_version_toolset to SCons.Tool.MSCommon. Given a version
      specification, this function will return an msvc version and an msvc toolset version.  The msvc
      toolset version may be None.  The msvc version and msvc toolset version can be used in the
      environment construction variables MSVC_VERSION and MSVC_TOOLSET_VERSION, respectively.  The
      version specification may be an msvc version or an msvc toolset version. This is a proxy for
      using an msvc toolset version to select an msvc instance. This function may be removed when an
      msvc toolset version is used during msvc instance selection.
    - Modify the MSCommon logger configuration to be independent of the root logger. This fixes an issue
      when multiple loggers are created and the MSCommon logger added computed fields to the root logger
      that are not present in other logging instances.
    - Modify the MSVC_USE_SCRIPT_ARGS test fixture to disable the msvc cache. This fixes an issue where
      the MSVC_USE_SCRIPT_ARGS test for success relied on a debug log message that was not produced when
      the msvc cache file exists and the test keys are already in the cache as the msvc script invocation
      was bypassed.

  From William Deegan:
    - Fix check for unsupported Python version. It was broken. Also now the error message
      will include what is the minimum supported version of Python
    - Fix ActionTests to work with python 3.10.1 (and higher)
    NOTE: If you build with Python 3.10.0 and then rebuild with 3.10.1 (or higher), you may
          see unexpected rebuilds. This is due to Python internals changing which changed
          the signature of a Python Action Function.
    - Fix a number of Python ResourceWarnings which are issued when running SCons and/or it's tests
      with python 3.9 (or higher)
    - Action._subproc() can now be used as a python context manager to ensure that the
      POpen object is properly closed.
      (Thanks to Mats Wichmann for catching that DummyPopen needed additional logic)
    - Added project_url for mailing lists and Discord
    - Updated project url in steup.cfg to be https instead of http
    - Updated setup.cfg to remove Python 3.5 and add Python 3.10
    - Added default values for source and target arguments to _defines() function. This
      is used to expand CPPDEFINES (and others). Previous change added those arguments
      with no defaults, so old usage where _defines() was called without source and target
      arguments would yield an exception. This issue was found via qt4 and qt5 tools in
      scons-contrib https://github.com/SCons/scons-contrib/issues/45

  From David H:
    - Add JavaScanner to include JAVACLASSPATH as a dependency when using the Java tool.
    - Fix incorrect Java classpath generation when a NodeList is used as part of any JAVA*PATH variables.

  From Daniel Moody:
    - Add cache-debug messages for push failures.
    - Ninja: Changed generated build.ninja file to run SCons only build Actions via
      a SCons Deamon. Added logic for starting and connecting to SCons daemon (currently
      only used for ninja)
    - Ninja: Fix issue where Configure files weren't being properly processed when build run
      via ninja.
    - Ninja: Added ninja mingw support and improved ninja CommandGeneratorAction support.
    - Ninja: Update ninja file generation to only create response files for build commands
      which exceed MAXLINELENGTH
    - Ninja: Added NINJA_GENERATED_SOURCE_ALIAS_NAME which allows user to specify an
      Alias() which the ninja tool can use to determine which files are generated sources.
      If this is not set by the user then the ninja tool will still dynamically determine
      which files are generated sources based on NINJA_GENERATED_SOURCE_SUFFIXES, and create
      a phony target _ninja_generated_sources. Generated sources will be built first by
      ninja. This is needed because ninja cannot determine which generated sources are
      required by other build targets. Code contributed by MongoDB
      The downstream commit is here:
      https://github.com/mongodb/mongo/commit/2fef432fa6e7cf3fd4f22ba3b193222c2887f14f
    - Ninja: Added special case for ninja scons daemon to work in win32 python3.6 environments.
      This particular environment does a bad job managing popen standard file handles, so
      some special workarounds are needed.
    - Ninja:Added user configurable setting of ninja depfile format via NINJA_DEPFILE_PARSE_FORMAT.
      Now setting NINJA_DEPFILE_PARSE_FORMAT to [msvc,gcc,clang] can force the ninja expected
      format. Compiler tools will also configure the variable automatically.
    - Ninja: Made ninja tool force the ninja file as the only target.
    - Ninja: Improved the default targets setup and made sure there is always a default target for
      the ninja file, which excludes targets that start and stop the daemon.
    - Ninja: Update ninja tool so targets passed to SCons are propagated to ninja when scons
      automatically executes ninja.
    - Small refactor of scons daemons using a shared StateInfo class for communication
      between the scons interactive thread and the http server thread. Added error handling
      for scons interactive failing to startup.
    - Ninja: Updated ninja scons daemon scripts to output errors to stderr as well as the daemon log.
    - Ninja: Fix typo in ninja scons daemon startup which causes ConnectionRefusedError to not retry
    - Added SHELL_ENV_GENERATORS construction variable. This variable should be set to a list
      (or an iterable) which contains functions to be called in order
      when constructing the execution environment (Generally this is the shell environment
      variables). This allows the user to customize how (for example) PATH is constructed.
      Note that these are called for every build command run by SCons. It could have considerable
      performance impact if not used carefully.
      to connect to the server during start up.
    - lex: Fixed an issue with the lex tool where file arguments specified to either "--header-file="
      or "--tables-file=" which included a space in the path to the file would be processed incorrectly
    - Ninja: added option "--skip-ninja-regen" to enable skipping regeneration of the ninja file
      if scons can determine the ninja file doesnot need to be regenerated, which will also
      skip restarting the scons daemon. Note this option is could result in incorrect rebuilds
      if scons Glob or scons generated files are used in ninja build target's command lines.
    - Ninja: Added new alias "shutdown-ninja-scons-daemon" to allow ninja to shutdown the daemon.
      Also added cleanup to test framework to kill ninja scons daemons and clean ip daemon logs.
      NOTE: Test for this requires python psutil module. It will be skipped if not present.
    - Ninja: Added command line variable NINJA_CMD_ARGS that allows to pass through ninja command line args.
      This can also be set in your Environment().

  From Mats Wichmann:
    - Tweak the way default site_scons paths on Windows are expressed to
      conform to conventions (what they actually resolve to is unchanged),
      drop a Py2 workaround, and pick a better "system" path, old one
      remains supported (%AllUsersProfile%\scons\site_scons vs old
      %AllUsersProfile%\Application Data\scons\site_scons).
    - Fix testsuite to work on Windows systems where there is no usable
      association for running .py files directly. There are a few tests where
      we need to do this for internal reasons, those are skipped in that case.
      Bad association could mean some other tool took it over (Visual
      Studio Code is known to do this), or no association at all.
    - Updated debug code in MSVC and MSVS tools to conform to the
      suggested "lazy interpolation" use of the Python logging module.
      Calls now look like 'debug("template %s", text)' rather than
      'debug("template %s" % text)' so the logging system does the
      interpolation only when/if needed (was a pylint warning).
    - Update Help (-H) output a bit. Drop "ignored for compat" entry.
      Pass window size to formatter so it formats for wider displays too.
    - runtest.py now accepts -j 0 to auto-detect number of usable
      processors for testing threads.
    - Fixed crash in C scanner's dictify_CPPDEFINES() function which happens if
      AppendUnique is called on CPPPATH. (Issue #4108).
    - The MSVC script_env_cache now contains a sanity check: if the retrieved
      tools path does not exist, the entry is invalidated so it will
      be recomputed, in an attempt to avoid scons failing when certain
      compiler version bumps have taken place.  The dictionary key (uses
      the name of a batch file and any arguments which may have been
      passes), is now computed a bit differently: the dashes are left
      off if there are no arguments.  The default cachefile is changed
      to have a .json suffix, for better recognition on Windows since
      the contents are json.
    - As "code modernization" all of SCons now uses the current super()
      zero-argument syntax instead of direct calls to a parent class method
      or the super() two-argument syntax.
    - Renamed ParseFlag's internal data structure to "mapping" instead of
      "dict" (avoid redefining builtin)
    - Fix an old use-before-set bug in tex tool (issue #2888)
    - Fix a test harness exception returning stderr if a wait_for timed out.
    - ParseConfig now correctly passes the *unique* flag to a user-supplied
      flag-merging function.
    - Restore the ability of the content-timestamp decider to see that a
      a source which is a symlink has changed if the file-system target of
      that link has been modified (issue #3880)
    - Modernize a few tests that use now-deprecated unittest.getTestCaseNames
      and unittest.makeSuite - Python itself suggests the replacements.
    - SCons.Tool.find_program_path now takes an optional add_path argument
      to add a path to the execution environment if it was discovered in
      default_paths. Previously, the routine, called by many tool modules,
      never altered the execution environment, leaving it to the tools.
    - A new construction variable FORTRANCOMMONFLAGS is added which is
      applied to all Fortran dialects, in case someone needs to set some
      flags globally. FORTRANFLAGS looked like it was intended for that,
      but was not applied to other dialects, and e2e tests explicitly checked
      that FORTRANFLAGS did not propagate outside the FORTRAN dialect,
      so the conclusion is that behavior is intentional (issue #2257)
    - SCons programmatic importing (tool modules and platform modules)
      no longer uses the deprecated (since Py 3.10) importlib.load_module
      routine, shifting to the preferred exec_module.  Old Python 2 compatible
      import fallback (using the imp module) in tool module loading is dropped.
      Tool module loading no longer special-cases Jython, which is a dead
      project as far as SCons (no timeline in sight for Python 3 support).
    - Improvements to lex and yacc tools: better documentation of
      extra-file options, add test for extra-file behavior.
      -  Two new construction variables are introduced for lex (LEX_HEADER_FILE
      and LEX_TABLES_FILE) as the preferred way of specifying these extra-file
      options.
      -  Two new construction variables are introduced for yacc
      (YACC_HEADER_FILE and YACC_GRAPH_FILE) as the preferred way of
      specifying these extra-file options.


  From Zhichang Yu:
    - Added MSVC_USE_SCRIPT_ARGS variable to pass arguments to MSVC_USE_SCRIPT.
    - Added Configure.CheckMember() checker to check if struct/class has the specified member.

  From Ivan Kravets, PlatformIO:
    - Conditional C/C++ Preprocessor: Strip shell's backslashes from the computed include (-DFOO_H=\"foo.h\")

RELEASE 4.3.0 - Tue, 16 Nov 2021 18:12:46 -0700

  From Jacob Cassagnol:
    - Default hash algorithm check updated for SCons FIPS compliance. Now checks for hash viability
      first and then walks the tree to use the first viable hash as the default one. This typically
      selects SHA1 on FIPS-enabled systems less than Python 3.9 as the new default instead of MD5,
      unless SHA1 has also been disabled by security policy, at which point SCons selects SHA256
      as the default. For systems running Python 3.9 and later, the hashlib bug has been fixed,
      and SCons will once again default to MD5 as the preferred algorithm.

  From Joseph Brill:
    - Fix MSVS tests (vs-N.N-exec.py) for MSVS 6.0, 7.0, and 7.1 (import missing module).
    - Add support for Visual Studio 2022.

  From William Deegan:
    - Fix reproducible builds. Restore logic respecting SOURCE_DATE_EPOCH when set.
    - Fix version tests to work with updated scons --version output. (Date format changed)
    - Fix issue #4021.  Change the way subst() is used in Textfile() to not evaluate '$$(' -> '$',
      but instead it should yield '$('.
    - Change SCons.Platform.win32.get_architecture() to return platform.platform() when run in an
      environment where neither: PROCESSOR_ARCHITEW6432 nor PROCESSOR_ARCHITECTURE is set.
      This should fix platform tests which started failing when HOST_OS/HOST_ARCH changes
      introduced by Aaron Franke (listed below) were merged.
    - Further PCH updates. It's now recommended that env['PCH'] should always be a File node.
      Either via return value from env.PCH() or by explicitly using File('StdAfx.pch').
    - Added --no-ignore-skips to runtest.py. Changed default to ignore skips when setting
      runtest.py's exit status. Previously would exit 2 if any tests were skipped.
      Now will only exit 2 if user specifies --no-ignore-skips and some tests were skipped.

  From Ryan Egesdahl:
    - Small fix to ensure CLVar default value is an empty list.
      See MongoDB bug report: https://jira.mongodb.org/browse/SERVER-59656
      Code contributed by MongoDB.
    - Ninja - Fixed an issue where if you control-c and/or killed ninja while it was running scons to
      regenerate build.ninja you would end up with no build.ninja file and have to rerun scons from scratch.
      Code contributed by MongoDB.

  From Aaron Franke:
    - Define HOST_OS and HOST_ARCH in the environment for all platforms.
      Before this change, these were only defined for Win32 and OS/2.

  From Daniel Moody:
    - Fix ninja tool to never use for_sig substitution because ninja does not use signatures. This
      issue affected CommandGeneratorAction function actions specifically.
    - Expanded ninja Mkdir to also support Mkdir actions.
    - Added support for the PCH environment variable to support subst generators.
    - Fix command line escaping for ninja dollar sign escape. Without escaping ninja properly,
      the ninja file scons regenerate and callback invocations will lose the $ characters used in
      the scons command line which ninja uses itself for escaping. For Example:
          scons BUILD=xyz OTHERVAR=$BUILD
      Prior to this fix, it would cause ninja to fail to escape the dollar sign, leading to the
      single dollar sign being used as a ninja escape character in the ninja file.

  From Daniel Moody:
    - Added ninja API 'NINJA_FORCE_SCONS_BUILD' to force a node to callback to scons.

  From Mats Wichmann:
    - Two small Python 3.10 fixes: one more docstring turned into raw
      because it contained an escape; updated "helpful" syntax error message
      from 3.10 was not expected by SubstTests.py and test/Subst/Syntax.py
    - EmitterProxy rich comparison set is completed (checker warning).
      Added __le__, __gt__, __ge__.
    - Fix gcc/g++ tool failing if "gcc --version" returns text which fails
      to_String conversion (i.e., not UTF-8) - failure happens when tool
      initialization checks version. For gcc, the initial version string is
      not translated, for the rest, don't convert, just consume raw and discard.
    - Maintenance and doc: modernize some usage in Scanner package,
      calling super(), switching some imitialization to comprehensions,
      and code formatting.  Docstring for scanner Base moved from
      init-method to class-level so it's picked up by Sphinx.
      Added new sconsign filenames to skip_entry_list in Scanner/Dir.py
    - Change SCons.Scanner.Base to ScannerBase. Old name kept as an alias
      but is now unused in SCons itself.
    - Call Variables option converter consistently - the converter should
      have access to the env if it needs to (issue #2064).
    - Fixed the variables Add() method to accept a tuple for the variable
      name the same way AddVariables() does (issue #3869).
    - The premade validator PathIsDirCreate for for PathVariable now catches
      the case where the directory could not be created due to permission
      problems, allowing a more helpful error to be emitted (issue #2828)
    - Maintenance: Python thread.setDaemon is deprecated in favor of
      directly updating daemon attribute - update SCons to do this.
    - Make sure when subst'ing a callable, the callable is called with
      the correct for_signature value, previously it would be true even
      if doing SUBST_RAW (issue #4037)
    - Update Util/NodeList implementation to get rid of a workaround for
      early Python 3 slicing issue that is no longer a problem.
    - Rework some Java tests to skip rather than fail on CI systems, where
      the working java is > v9, but a 1.8 or 9 was also found.
    - Java updates: on Windows, detect more default JDK install locations.
      On all platforms, more Java versions (up to 17.0 now).  Add more information
      on version selection to docs.
      Update docs on JavaH tool in light of javah command dropped since 10.0.
      Try to be better about preserving user's passed-in JAVA* construction vars.
    - Start the deprecation of the qt tool, which refers to Qt3 (usupported
      since around 2006). There's a deprecation warning added, initially
      defaulting to disabled.

  From Brian Quistorff:
    - Fix crash when scons is run from a python environement where a signal
      is set from outside Python.


RELEASE 4.2.0 - Sat, 31 Jul 2021 18:12:46 -0700

  From Byron Platt:
    - Fix Install() issue when copytree recursion gives bad arguments that can
      lead to install side-effects including keeping dangling symlinks and
      silently failing to copy directories (and their subdirectories) when the
      directory already exists in the target.

  From Joseph Brill:
    - Internal MSVS update: Remove unnecessary calls to find all installed versions of msvc
      when constructing the installed visual studios list.

  From William Deegan:
    - Improve Subst()'s logic to check for proper callable function or class's argument list.
      It will now allow callables with expected args, and any extra args as long as they
      have default arguments. Additionally functions with no defaults for extra arguments
      as long as they are set using functools.partial to create a new callable which set them.
    - Fix Issue #3035 - mingw with SHLIBVERSION set fails with either not a dll error or
      "Multiple ways to build the same target were specified for:".  Now mingw will disable
      creating the symlinks (and adding version string to ) dlls.  It sets SHLIBNOVERSIONSYMLINKS,
      IMPLIBNOVERSIONSYMLINKS and LDMODULENOVERSIONSYMLINKS to True.
    - Added --experimental flag, to enable various experimental features/tools.  You can specify
      'all', 'none', or any combination of available experimental features.
    - Fix Issue #3933 - Remove unguarded print of debug information in SharedLibrary logic when
      SHLIBVERSION is specified.
    - Fix versioned shared library naming for MacOS platform. (Previously was libxyz.dylib.1.2.3,
      has been fixed to libxyz.1.2.3.dylib. Additionally the sonamed symlink had the same issue,
      that is now resolved as well)
    - Add experimental ninja builder. (Contributed by MongoDB, Daniel Moody and many others).
    - Fix #3955 - _LIBDIRFLAGS leaving $( and $) in *COMSTR output.  Added affect_signature flag to
      _concat function.  If set to False, it will prepend and append $( and $). That way the various
      Environment variables can use that rather than "$( _concat(...) $)".
    - Fix issue with exparimental ninja tool which would fail on windows or when ninja package wasn't
      installed but --experimental=ninja was specified.
    - As part of experimental ninja tool, allow SetOption() to set both disable_execute_ninja and
      disable_ninja.

  From David H:
    - Fix Issue #3906 - `IMPLICIT_COMMAND_DEPENDENCIES` was not properly disabled when
      set to any string value (For example ['none','false','no','off'])
      Also previously 'All' wouldn't have the desired affect.

  From Ivan Kravets:
    - Provide a custom argument escape function for `TempFileMunge` using a new
      `TEMPFILEARGESCFUNC` variable. Useful if you need to apply extra operations on
      a command argument before writing to a temporary file (fix Windows slashes,
      normalize paths, etc.)

  From Henrik Maier:
   - DocbookXslt tool: The XSLT stylesheet file is now initialized to an env.File() Node,
     such that dependencies work correctly in hierarchical builds (eg when using
     DocbookXslt in SConscript('subdir/SConscript') context.

  From Daniel Moody:
    - Update CacheDir to use uuid for tmpfile uniqueness instead of pid.
      This fixes cases for shared cache where two systems write to the same
      cache tmpfile at the same time because the happened to get the same pid.
    - Added support for passing custom CacheDir derived classes to SCons. Moved
      copy_from_cache attribute from the Environment class to CacheDir class.
      Code contributed by MongoDB.
    - Update BuildTask to pass all targets to the progress object fixing an issue
      where multi-target build nodes only got the first target passed to the progress
      object.
    - Fix a potential race condition in shared cache environments where the permissions are
      not writeable for a moment after the file has been renamed and other builds (users) will copy
      it out of the cache. Small reorganization of logic to copy files from cachedir. Moved CacheDir
      writeable permission code for copy to cache behind the atomic rename operation.
    - Added marking of intermediate and and multi target nodes generated from SConf tests so that
      is_conftest() is more accurate.
    - Added test for configure check failing to ensure it didn't break generating and running ninja.


  From Mats Wichmann:
    - Initial support in tests for Python 3.10 - expected bytecode and
      one changed expected exception message. Change some more regexes
      to be specified as rawstrings in response to DeprecationWarnings.
    - Add an example of adding an emitter to User Guide (concept
      from Jeremy Elson)
    - Add timing information for sconsign database dump when --debug=time
      is selected. Also switch to generally using time.perf_counter,
      which is the Python recommended way for timing short durations.
    - Drop remaining definitions of dict-like has_key methods, since
      Python 3 doesn't have a dictionary has_key (maintenance)
    - Do not treat --site-dir=DIR and --no-site-dir as distinct options.
      Allows a later instance to override an earlier one.
    - Ignore empty cmdline arguments when computing targets (issue 2986)
    - Remove long-deprecated construction variables PDFCOM, WIN32_INSERT_DEF,
      WIN32DEFPREFIX, WIN32DEFSUFFIX, WIN32EXPPREFIX, WIN32EXPSUFFIX.
      All have been replaced by other names since at least 1.0.
    - Add a __iadd__ method to the CLVar class so that inplace adds
      (+=) also work as expected (issue 2399)
    - Remove local copy of CLVar in EnvironmentTests unittest file -
      should be testing against the production version, and they
      didn't really differ.
    - Don't strip spaces in INSTALLSTR by using raw subst (issue 2018)
    - Deprecate Python 3.5 as a supported version.
    - CPPDEFINES now expands construction variable references (issue 2363)
    - Restore behavior that Install()'d files are writable (issue 3927)
    - Simplified Mkdir(), the internal mkdir_func no longer needs to handle
      existing directories, it can now pass exist_ok=True to os.makedirs().
    - Avoid WhereIs exception if user set a tool name to empty (from issue 1742)
    - Maintenance: remove obsolete __getslice__ definitions (Py3 never calls);
      add Node.fs.scandir to call new (Py3.5) os.scandir; Node.fs.makedirs
      now passes the exist_ok flag; Cachedir creation now uses this flag.
    - Maintenance: remove unneeded imports and reorganize some.  Fix uses
      of warnings in some tools which instantiated the class but did nothing
      with them, need to instead call SCons.Warnings.warn with the warn class.
    - Drop overridden changed_since_last_build method in Value class.
    - Resync the SetOption implementation and the manpage, making sure new
      options are available and adding a notes column for misc information.
      SetOption equivalents to --hash-chunksize, --implicit-deps-unchanged
      and --implicit-deps-changed are enabled.
    - Add tests for SetOption failing on disallowed options and value types.
    - Maintenance: eliminate lots of checker complaints about Util.py.
    - Maintenance: fix checker-spotted issues in Environment (apply_tools)
      and EnvironmentTests (asserts comparing with self).
      For consistency, env.Tool() now returns a tool object the same way
      Tool() has done.
    - Change SConscript() missing SConscript behavior - if must_exist=False,
      the warning is suppressed.
    - Make sure TEMPFILEPREFIX can be set to an empty string (issue 3964)

  From Dillan Mills:
    - Add support for the (TARGET,SOURCE,TARGETS,SOURCES,CHANGED_TARGETS,CHANGED_SOURCES}.relpath property.
      This will provide a path relative to the top of the build tree (where the SConstruct is located)
      Fixes #396

  From Andrew Morrow:
    - Fix issue #3790: Generators in CPPDEFINES now have access to populated source
      and target lists

RELEASE 4.1.0 - Tues, 19 Jan 2021 15:04:42 -0700

  From James Benton:
    - Add COMPILATIONDB_PATH_FILTER env option for CompilationDatabase() builder which allows
      filtering of entries based on the output file paths using glob style file matching (issue #3742).

  From Joseph Brill:
    - Internal MSVC and test updates: Rework the msvc installed versions cache so that it
      is not exposed externally and update external references accordingly.
    - Modify the MSCommon internal-use only debug logging records to contain the correct relative
      file path when the debug function is called from outside the MSCommon module.

  From William Deegan:
    - Fix yacc tool, not respecting YACC set at time of tool initialization.
    - Refactor SCons.Tool to move all common shared and loadable module linking logic to SCons.Tool.linkCommon
    - Remove pywin32 imports from SCons.Script.Main. No longer needed.
    - Switch to use ctypes instead of pywin32 (requiring an extra pip install) - Fixes Github Issue #2291
       - pywin32 no longer necessary for SCons install. (pip install SCons will no longer also require pywin32 on win32)
       - Remove pywin32 usage from SCons.Util where it was used for accessing the registry. Python native winreg
         library already includes this functionality.
       - Remove using pywin32 to retrieve peak memory usage on Win32 for `--debug=memory`
    - Fix Issue #3759 - include scons.1, sconsign.1, scons-time.1 manpages in sdist and wheel packages.
    - Change SCons's build so the generated `SCons/__init__.py` is no longer removed by `scons -c`
    - Completely rewrote versioned shared libraries logic. Added support for SOVERSION via dmoody's initial PR #3733
    - No longer automatically disable setting SONAME on shared libraries on OpenBSD.
    - Fix race condition bug when initializing a scons cache directory at the
      same time from multiple threads or processes. Problem described in PR #3114.
      This is a simpler fix which should avoid some problems identified with the initial PR.
      (Credit to Fredrik Medley for reporting the issue, the initial PR, and discussing and testing
       this solution)
    - Minor edits to User Guide and manpage's header with copyright, released date changed.

  From Michał Górny:
    - Fix dvipdf test failure due to passing incorrect flag to dvipdf.

  From Adam Gross:
    - Fix minor bug affecting SCons.Node.FS.File.get_csig()'s usage of the MD5 chunksize.
      User-facing behavior does not change with this fix (GH Issue #3726).
    - Fix occasional test failures caused by not being able to find a file or directory fixture
      when running multiple tests with multiple jobs.
    - Added support for a new command-line parameter `--hash-format` to override the default
      hash format that SCons uses. It can also be set via `SetOption('hash_format')`. Supported
      values are: `md5`, `sha1`, and `sha256`. For all hash formats other than
      the default of `md5`, the SConsign database will include the name of the hash format.
      For example, `--hash-format=sha256` will create a SConsign with name
      `.sconsign_sha256.dblite.`.
    - Fix incorrect cache hits and/or misses when running in interactive mode by having
      SCons.Node.Node.clear() clear out all caching-related state.
    - Change Environment.SideEffect() to not add duplicate side effects.
      NOTE: The list of returned side effect Nodes will not include any duplicate side effect Nodes.
    - Add support to the Python scanner for finding dynamically generated dependencies.
      Previously the scanner only found imports if they existed on disk at scanning time.

  From David H:
    - Add ZIP_OVERRIDE_TIMESTAMP env option to Zip builder which allows for overriding of the file
      modification times in the archive.
    - Fix Zip builder not rebuilding when ZIPROOT env option was changed.

  From Jason Kenny
    - Fix python3 crash when Value node get_text_content when child content does not have decode()
      NOTE: If you depend on Value node's get_text_content returning concatenated contents of it's
      children. This may break your code. It now concatenates the csig() of all children.

  From Joachim Kuebart:
    - Suppress missing SConscript deprecation warning if `must_exist=False`
      is used.

  From Rocco Matano:
    - Fix Zip tool to respect ZIPCOMSTR. Previously all zip builder calls would yield something
      like zip(["test.zip"], ["zip_scons.py"]) and ignore ZIPCOMSTR if ZIPCOM and ZIPCOMSTR
      weren't set after the Environment/Tool is initialized. (Explained in PR #3659)

  From Daniel Moody:
    - Fix issue where java parsed a class incorrectly from lambdas used after a new.

  From Simon Tegelid
    - Fix using TEMPFILE in multiple actions in an action list. Previously a builder, or command
      with an action list like this:
      ['${TEMPFILE("xxx.py -otempfile $SOURCE")}', '${TEMPFILE("yyy.py -o$TARGET tempfile")}']
      Could yield a single tempfile with the first TEMPFILE's contents, used by both steps
      in the action list.

  From Mats Wichmann:
    - Complete tests for Dictionary, env.keys() and env.values() for
      OverrideEnvironment. Enable env.setdefault() method, add tests.
    - Raise an error if an option (not otherwise consumed) is used which
      looks like an abbreviation of one one added by AddOption. (#3653)
    - Tool module not found will now raise a UserError to more clearly indicate this is
      probably an SConscript problem, and to make the traceback more relevant.
    - Fix three issues with MergeFlags:
      - Signature/return did not match documentation or existing usage - the implementation
        now no longer returns the passed env
      - merging --param arguments did not work (issue #3107);
      - passing a dict to merge where the values are strings failed (issue #2961).
    - Include previously-excluded SideEffect section in User Guide.
    - Clean up unneeded imports (autoflake tool).
    - Make sure cProfile is used if profiling - SCons was expecting
      the Util module to monkeypatch in cProfile as profile if available,
      but this is no longer being done.
    - Cleanup in SCons.Util.AddMethod. If called with an environment instance
      as the object to modify, the method would not be correctly set up in
      any Clone of that instance.  Now tries to detect this and calls
      MethodWrapper to set up the method the same way env.AddMethod does.
      MethodWrapper moved to Util to avoid a circular import. Fixes #3028.
    - Some Python 2 compatibility code dropped
    - Rework runtest.py to use argparse for arg handling (was a mix
      of hand-coded and optparse, with a stated intent to "gradually port").
    - Add options to runtest to generate/not generate a log of failed tests,
      and to rerun such tests. Useful when an error cascades through several
      tests, can quickly try if a change improves all the fails. Dropped
      runtest test for fallback from qmtest, not needed; added new tests.
    - Eliminate tex tool usage of "for foo in range(len(iterable))"
    - Restore internal Trace function to functional state.
    - Only try to initialize the wix tool by default (or when tool `default` is explicitly installed)
      on Windows based systems.
    - Pick a better "Topic" Trove classifier for SCons: SW Dev / Build Tools
    - Use os.replace instead of os.rename in dblite so don't need to
      special-case Windows here. dblite is the default storage engine for the SConsign file(s).
    - Fix cut-n-paste error in msvc debug printout and make some debug output
      in msvs and msvsTests.py be off until needed (uncomment to use)
    - Fix Issue #3014 - Empty file and missing file have same csig
    - Refactor env.Append/Prepend to remove Py 1.5 era need to nest
      try blocks, can now "continue" at the appropriate places.
    - Add /snap/bin to env['PATH'] on POSIX, although this is only
      really useful for a subset of POSIX systems that use snaps.
      Was needed for CI builds, which run on Ubuntu LTS images.
    - Eliminate Py2-ism __nonzero__ (now __bool__). Work around issue #3860
      where a check for BuilderBase raising exc. on __bool__ was optimized out.
      This issue was found due to a bug in Python 3.10.0a4. See issue #3860 for details.


RELEASE 4.0.1 - Mon, 16 Jul 2020 16:06:40 -0700

  From Rob Boehne:
    - Fix fortran tools to set SHFORTRAN variables to $FORTRAN, similarly SHF77, SHF90, SHF95,
      SHF03 and SHF08 will default to the variables $F77, $F90, $F95, $F03 and $F08 respectively.
      If you were depending on changing the value of FORTRAN (or $F[0-9][0-9]) having no effect
      on the value of SHFORTRAN, this change will break that.   The values of FORTRAN, F77, F90,
      F95, F03, F08 and SHFORTRAN, SHF77 (etc.) now are not overridden in generate if alredy set
      by the user.
    - Fix subprocess execution of 'lslpp' on AIX to produce text standard i/o.
    - Re-do the fix for suncxx tool (Oracle Studio compiler) now that only Python 3 is supported,
      to avoid decoding errors.

  From William Deegan:
    - Added Environment() variable TEMPFILEDIR which allows setting the directory which temp
      files createdby TEMPFILEMUNGE are created in.

  From Daniel Moody:
    - Added method on Node to test if its node used in SConf. (Github Issue #3626)



RELEASE 4.0.0 - Sat, 04 Jul 2020 12:00:27 +0000

  From Dirk Baechle:
    - Updated documentation toolchain to work properly under Python3, also
      removed libxslt support from the Docbook Tool. (issue #3580)
    - Added Docker images for building and testing SCons. (issue #3585)


  From James Benton:
    - Improve Visual Studio solution/project generation code to add support
      for a per-variant cppflags. Intellisense can be affected by cppflags,
      this is especially important when it comes to /std:c++* which specifies
      what C++ standard version to target. SCons will append /Zc:__cplusplus
      to the project's cppflags when a /std:c++* flag is found as this is
      required for intellisense to use the C++ standard version from cppflags.

  From Rob Boehne
    - Specify UTF-8 encoding when opening Java source file as text.  By default, encoding is the output
    of locale.getpreferredencoding(False), and varies by platform.

  From Joseph Brill:
    - MSVC updates: When there are multiple product installations (e.g, Community and
      Build Tools) of MSVC 2017 or MSVC 2019, an Enterprise, Professional,
      or Community installation will be selected before a Build Tools installation when
      "14.1" or "14.2" is requested, respectively. (GH Issue #3699).
    - MSVC updates: When there are multiple product installations of MSVC 2017 (e.g.,
      Community and Express), 2017 Express is no longer returned when "14.1" is
      requested.  Only 2017 Express will be returned when "14.1Exp" is requested.
      (GH Issue #3699).
    - MSVC updates: An MSVC 6.0 installation now appears in the installed versions list
      when msvc debug output is enabled (GH Issue #3699).
    - MSVS test updates: Tests for building a program using generated MSVS project and
      solution files using MSVS 2015 and later now work as expected on x86 hosts.
    - Test update: Reduce the number of "false negative" test failures for the interactive
      configuration test (test/interactive/configure.py).
    - MSVS update: Fix the development environment path for MSVS 7.0.

  From William Deegan:
    - Fix broken clang + MSVC 2019 combination by using MSVC configuration logic to
      propagate'VCINSTALLDIR' and 'VCToolsInstallDir' which clang tools use to locate
      header files and libraries from MSVC install. (Fixes GH Issue #3480)
    - Added C:\msys64\mingw64\bin to default mingw and clang windows PATH's.  This
      is a reasonable default and also aligns with changes in Appveyor's VS2019 image.
    - Drop support for Python 2.7. SCons will be Python 3.5+ going forward.
    - Change SCons.Node.ValueWithMemo to consider any name passed when memoizing Value() nodes
    - Fix Github Issue #3550 - When using Substfile() with a value like Z:\mongo\build\install\bin
      the implementation using re.sub() would end up interpreting the string and finding regex escape
      characters where it should have been simply replacing existing text. Switched to use string.replace().
    - Fix Github Issue #2904 - Provide useful error message when more than one Configure Contexts are opened.
      Only one open is allowed. You must call conf.Finish() to complete the currently open one before creating another
    - Add msys2 installed mingw default path to PATH for mingw tool.
      - C:\msys64\mingw64\bin
    - Purge obsolete internal build and tooling scripts
    - Allow user specified location for vswhere.exe specified by VSWHERE.
      NOTE: This must be set at the time the 'msvc' 'msvs' and/or 'mslink' tool(s) are initialized to have any effect.
    - Resolve Issue #3451 and Issue #3450 - Rewrite SCons setup.py and packaging. Move script logic to entry points so
      package can create scripts which use the correct version of Python.
    - Resolve Issue #3248 - Removing '-Wl,-Bsymbolic' from SHLIBVERSIONFLAGS
      NOTE: If your build depends on the above you must now add to your SHLIBVERSIONFLAGS
    - Speedup bin/docs-update-generated by caching parsed docbook schema. (60x speedup)
    - Reorganized source tree. Moved src/engine/SCons to SCons to be more in line with current Python source
      tree organization practices.
    - Renamed as.py to asm.py and left redirecting tool.  'as' is a reserved word and so
      changing the name was required as we wanted to import symbols for use in compilation_db
      tool.
    - Add CompilationDatabase() builder in compilation_db tool. Contributed by MongoDB.
      Setting COMPILATIONDB_USE_ABSPATH to True|False controls whether the files are absolute or relative
      paths.  Address Issue #3693 and #3694 found during development.
    - Fixed Github Issue 3628 - Hardcoding pickle protocol to 4 (supports python 3.4+)
      and skipping Python 3.8's new pickle protocol 5 whose main advantage is for out-of-band data buffers.
      NOTE: If you used Python 3.8 with SCons 3.0.0 or above, you may get a a pickle protocol error. Remove your
      .sconsign.dblite. You will end up with a full rebuild.

  From Andrii Doroshenko:
    - Extended `Environment.Dump()` to select a format to serialize construction variables (pretty, json).

  From Jeremy Elson:
    - Updated design doc to use the correct syntax for Depends()

  From Adam Gross:
    - Added support for scanning multiple entries in an action string if
      IMPLICIT_COMMAND_DEPENDENCIES is set to 2 or 'all'. This enables more thorough
      action scanning where every item in each command line is scanned to determine
      if it is a non-source and non-target path and added to the list of implicit dependencies
      for the target.
    - Added support for taking instances of the Value class as implicit
      dependencies.
    - Added new module SCons.Scanner.Python to allow scanning .py files.
    - Added support for explicitly passing a name when creating Value() nodes. This may be useful
      when the value can't be converted to a string or if having a name is otherwise desirable.
    - Fixed usage of abspath and path for RootDir objects on Windows. Previously
      env.fs.Dir("T:").abspath would return "T:\T:" and now it correctly returns "T:".

  From Ivan Kravets, PlatformIO
    - New conditional C Scanner (`SCons.Scanner.C.CConditionalScanner()`)
      which interprets C/C Preprocessor conditional syntax (#ifdef, #if, #else,
      #elif, #define, etc.)
    - Improvements for virtual C Pre-Processor:
      * Handle UNSIGNED LONG and LONG numeric constants in DEC (keep support for HEX)
      * Skip unrecognized directives, such as `#if( defined ...)`
      * Ignore `#include DYNAMIC_INCLUDE` directive that depends on a dynamic
        macro which is not located in a state TABLE.
      * Cleanup CPP expressions before evaluating (strip comments, carriage returns)

  From Iosif Kurazs:
    - Added a new flag called "linedraw" for the command line argument  "--tree"
      that instructs scons to use single line drawing characters to draw the dependency tree.

  From Daniel Moody:
    - Add no_progress (-Q) option as a set-able option. However, setting it in the
      SConstruct/SConscript will still cause "scons: Reading SConscript files ..." to be
      printed, since the option is not set when the build scripts first get read.
    - Added check for SONAME in environment to setup symlinks correctly (Github Issue #3246)
    - User callable's called during substition expansion could possibly throw a TypeError
      exception, however SCons was using TypeError to detect if the callable had a different
      signature than expected, and would silently fail to report user's exceptions. Fixed to
      use signature module to detect function signature instead of TypeError. (Github Issue #3654)
    - Added storage of SConstructs and SConscripts nodes into global set for checking
      if a given node is a SConstruct/SConscript.
      Added new node function SCons.Node.is_sconscript(self) (Github Issue #3625)

  From Andrew Morrow:
    - Fix Issue #3469 - Fixed improper reuse of temporary and compiled files by Configure when changing
      the order and/or number of tests.  This is done by using the hash of the generated temporary files
      content and (For the target files) the hash of the action.
      So where previously files would be named:
      - config_1.c, config_1.o, config_1
      The will now be named (For example)
      - conftest_68b375d16e812c43e6d72d6e93401e7c_0.c,
        conftest_68b375d16e812c43e6d72d6e93401e7c_0_5713f09fc605f46b2ab2f7950455f187.o
        or
        conftest_68b375d16e812c43e6d72d6e93401e7c_0.o
        conftest_68b375d16e812c43e6d72d6e93401e7c_0_5713f09fc605f46b2ab2f7950455f187 (for executable)

  From Mathew Robinson:
    - Improve performance of Subst by preventing unnecessary frame
      allocations by no longer defining the *Subber classes inside of their
      respective function calls.
    - Improve performance of Subst in some cases by preventing
      unnecessary calls to eval when a token is surrounded in braces
      but is not a function call.
    - Improve performance of subst by removing unnecessary recursion.
    - Cleanup dangling symlinks before running builders (Issue #3516)

  From Mats Wichmann:
    - Remove deprecated SourceCode
    - str.format syntax errors fixed
    - a bunch of linter/checker syntax fixups
    - Convert remaining uses of insecure/deprecated mktemp method.
    - Clean up some duplications in manpage.  Clarify portion of manpage on Dir and File nodes.
    - Reduce needless list conversions.
    - Fixed regex in Python scanner.
    - Accommodate VS 2017 Express - it's got a more liberal license then VS
      Community, so some people prefer it (from 2019, no more Express)
    - vswhere call should also now work even if programs aren't on the C: drive.
    - Add an alternate warning message if cl.exe is not found and msvc config
      cache is in use (SCONS_CACHE_MSVC_CONFIG was given) - config cache
      may be out of date.
    - Fixed bug where changing TEXTFILESUFFIX would cause Substfile() to rebuild. (Github Issue #3540)
    - Script/Main.py now uses importlib instead of imp module.
    - Drop some Python 2-isms.
    - MSVC updates: pass on VSCMD_DEBUG and VSCMD_SKIP_SENDTELEMETRY to msvc
      tool setup if set in environment. Add Powershell to default env
      (used to call telemetry script).
    - Microsoft Visual Studio - switch to using uuid module to generate GUIDs rather than hand rolled
      method using md5 directly.
      NOTE: This change affects the following builders' output. If your build depends on the output of these builders
      you will likely see a rebuild.
      * Package() (with PACKAGETYPE='msi')
      * MSVSSolution()
      * MSVSProject()
    - Docbook builder provides a fallback if lxml fails to generate
      a document with tostring().
    - Fix description of ARCOMSTR constr. var. (issue 3636). Previously the text was a copy of ASCOMSTR which
      has different function.
    - Update xml files in SCons to reflect changed relative paths after
      code restructuring (src/engine/SCons -> SCons)
    - Preliminary Python 3.9 support - elimination of some warnings.
    - Drop the with_metaclass jig which was designed to let class
      definitions using a metaclass be written the same for Py2/Py3.
    - Bump python_version_unsupported (and deprecated) to indicate 3.5
      is lowest supported Python.
    - ParseFlags should not modify the user's passed in dict in case it's
      a compound data structure (e.g. values are lists) (issue #3665)
    - In Py3 classes no longer need to be listed as deriving from object.
    - Remove deprecated check for Task subclasses needing a needs_execute
      method - this is now enforced via an abstract base class, so the
      check and test is no longer needed.
    - Close various logfiles (trace, cache, taskmastertrace, configure)
      when done using atexit calls.
    - Rebase forked copy of shutil.copytree to Python 3.7 stlib version.
    - Significant rework of documentation: API docs are now generated
      using Sphinx; manpage and user guide now use more "standard"
      markup elements (which could facilitate later conversion to a
      different doc format, should that choice be made); significant
      rewordings in manpage.  Manpage Examples moved to an external
      repository / website (scons-cookbook.readthedocs.io).
    - Clean up test harness and tests' use of subdir, file_fixture and
      dir_fixture.
    - SubstitutionEnvironment and OverrideEnvironment now have keys()
      and values() methods to better emulate a dict (already had items()).
    - Rename internal Warning base class to SConsWarning to avoid any
      possible confusion with Python's own Warning class.


RELEASE 3.1.2 - Mon, 17 Dec 2019 02:06:27 +0000

  From Edoardo Bezzeccheri
    - Added debug option "action_timestamps" which outputs to stdout the absolute start and end time for each target.

  From Rob Boehne
    - Fix suncxx tool (Oracle Studio compiler) when using Python 3.  Previously would throw an exception.
      Resolved by properly handling tool version string output as unicode.

  From Tim Gates
    - Resolved a typo in engine.SCons.Tool

  From Adam Gross:
    - Resolved a race condition in multithreaded Windows builds with Python 2
      in the case where a child process is spawned while a Python action has a
      file open. Original author: Ryan Beasley.
    - Added memoization support for calls to Environment.Value() in order to
          improve performance of repeated calls.


  From Jason Kenny
    - Update Command() function to accept target_scanner, source_factory, and target_factory arguments.
      This makes Command act more like a one-off builder.

  From Ivan Kravets
    - Added support for "-imacros" to ParseFlags

  From Jacek Kuczera:
    - Fix CheckFunc detection code for Visual 2019. Some functions
      (e.g. memmove) were incorrectly recognized as not available.

  From Jakub Kulik
    - Fix stacktrace when using SCons with Python 3.5+ and SunOS/Solaris related tools.

  From Philipp Maierhöfer:
    - Avoid crash with UnicodeDecodeError on Python 3 when a Latex log file in
      non-UTF-8 encoding (e.g. containing umlauts in Latin-1 encoding when
      the fontenc package is included with \usepackage[T1]{fontenc}) is read.

  From Mathew Robinson:
    - Improved threading performance by ensuring NodeInfo is shared
      across threads. Results in ~13% improvement for parallel builds
      (-j# > 1) with many shared nodes.
    - Improve performance of Entry.disambiguate() by making check for
      most common case first, preventing unnecessary IO.
    - Improved DAG walk performance by reducing unnecessary work when
      there are no un-visited children.

  From Mats Wichmann
    - Replace instances of string find method with "in" checks where
      the index from find() was not used.
    - CmdStringHolder fix from issue #3428
    - Turn previously deprecated debug options into failures:
      --debug=tree, --debug=dtree, --debug=stree, --debug=nomemoizer.
    - Experimental New Feature: Enable caching MSVC configuration
      If SCONS_CACHE_MSVC_CONFIG shell environment variable is set,
      SCons will cache the results of past calls to vcvarsall.bat to
      a file; integrates with existing memoizing of such vars.
      On vs2019 saves 5+ seconds per SCons invocation, which really
      helps test suite runs.
    - Remove deprecated SourceSignatures, TargetSignatures
    - Remove deprecated Builder keywords: overrides and scanner
    - Remove deprecated env.Copy
    - Remove deprecated BuildDir plus SConscript keyword build_dir
    - A number of documentation improvements.


RELEASE 3.1.1 - Mon, 07 Aug 2019 20:09:12 -0500

  From William Deegan:
    - Remove obsoleted references to DeciderNeedsNode which could cause crash when using --debug=explain

  From Jason Kenny
    - Add Fix and test for crash in 3.1.0 when using Decider('MD5-timestamp') and --debug=explain

  From Ben Reed:
    - Added -fmerge-all-constants to flags that get included in both CCFLAGS and LINKFLAGS.

  From Mathew Robinson:
    - Fix issue #3415 - Update remaining usages of EnvironmentError to SConsEnvironmentError
      this patch fixes issues introduced in 3.1.0 where any of the
      following would cause SCons to error and exit:
        - CacheDir not write-able
        - JSON encoding errors for CacheDir config
        - JSON decoding errors for CacheDir config

RELEASE 3.1.0 - Mon, 20 Jul 2019 16:59:23 -0700

  From Joseph Brill:
    - Code to supply correct version-specifier argument to vswhere for
      VS version selection.

  From William Deegan:
    - Enhanced --debug=explain output. Now the separate components of the dependency list are split up
      as follows:

      scons: rebuilding `file3' because:
           the dependency order changed:
           ->Sources
           Old:xxx  New:zzz
           Old:yyy  New:yyy
           Old:zzz  New:xxx
           ->Depends
           ->Implicit
           Old:/usr/bin/python  New:/usr/bin/python
    - Fix Issue #3350 - SCons Exception EnvironmentError is conflicting with Python's EnvironmentError.
    - Fix spurious rebuilds on second build for cases where builder has > 1 target and the source file
      is generated. This was causing the > 1th target to not have it's implicit list cleared when the source
      file was actually built, leaving an implicit list similar to follows for 2nd and higher target
              ['/usr/bin/python', 'xxx', 'yyy', 'zzz']
      This was getting persisted to SConsign and on rebuild it would be corrected to be similar to this
              ['zzz', 'yyy', 'xxx', '/usr/bin/python']
      Which would trigger a rebuild because the order changed.
      The fix involved added logic to mark all shared targets as peers and then ensure they're implicit
      list is all cleared together.
    - Fix Issue #3349 - SCons Exception EnvironmentError is conflicting with Python's EnvironmentError.
      Renamed to SConsEnvironmentError
    - Fix Issue #3350 - mslink failing when too many objects.  This is resolved by adding TEMPFILEARGJOIN variable
      which specifies what character to join all the argements output into the tempfile. The default remains a space
      when mslink, msvc, or mslib tools are loaded they change the TEMPFILEARGJOIN to be a line separator (\r\n on win32)
    - Fix performance degradation for MD5-timestamp decider.  NOTE: This changes the Decider() function arguments.
      From:
          def my_decider(dependency, target, prev_ni):
      To:
          def my_decider(dependency, target, prev_ni, repo_node):
      Where repo_node is the repository (or other) node to use to check if the node is out of date instead of dependency.

  From Peter Diener:
    - Additional fix to issue #3135 - Also handle 'pure' and 'elemental' type bound procedures
    - Fix issue #3135 - Handle Fortran submodules and type bound procedures

  From Adam Gross:
    - Upgraded and improved Visual Studio solution/project generation code using the MSVSProject builder.
      - Added support for Visual Studio 2017 and 2019.
      - Added support for the following per-variant parameters to the builder:
        - cpppaths: Provides per-variant include paths.
        - cppdefines: Provides per-variant preprocessor definitions.

  From Michael Hartmann:
    - Fix handling of Visual Studio Compilers to properly reject any unknown HOST_PLATFORM or TARGET_PLATFORM

  From Bert Huijben:
    - Added support for Visual Studio 2019 toolset.

  From Mathew Robinson:
    - Update cache debug output to include cache hit rate.
    - No longer unintentionally hide exceptions in Action.py
    - Allow builders and pseudo-builders to inherit from OverrideEnvironments

  From Leonard de Ruijter:
    - Add logic to derive correct version argument to vswhere

  From Lukas Schrangl:
    - Enable LaTeX scanner to find more than one include per line

  From  Sergey Torokhov:
    - Recognize jdk on Gentoo systems.

  From Mats Wichmann:
    - scons-time takes more care closing files and uses safer mkdtemp to avoid
      possible races on multi-job runs.
    - Use importlib to dynamically load tool and platform modules instead of imp module
    - sconsign: default to .sconsign.dblite if no filename is specified.
      Be more informative in case of unsupported pickle protocol (py2 only).
    - Fix issue #3336 - on Windows, paths were being added to PATH even if
      tools were not found in those paths.
    - More fixes for newer Java versions (since 9): handle new jdk directory
      naming (jdk-X.Y instead of jdkX.Y) on Windows; handle two-digit major
      version. Docstrings improved.
    - Fixups for pylint: exception types, redefined functions,
      globals, etc.  Some old code removed to resolve issues (hashlib is
      always present on modern Pythons; no longer need the code for
      2.5-and-earlier optparse). cmp is not a builtin function in Py3,
      drop one (unused) use; replace one.  Fix another instance of
      renaming to SConsEnvironmentError. Trailing whitespace.
      Consistently use not is/in (if not x is y -> if x is not y).
    - Add a PY3-only function for setting up the cachedir that should be less
      prone to races. Add a hack to the PY2 version (from Issue #3351) to
      be less prone to a race in the check for old-style cache.
    - Fix coding error in docbook tool only exercised when using python lxml
    - Recognize two additional GNU compiler header directory options in
      ParseFlags: -iquote and -idirafter.
    - Fix more re patterns that contain \ but not specified as raw strings
      (affects scanners for D, LaTeX, swig)


RELEASE 3.0.5 - Mon, 26 Mar 2019 15:04:42 -0700

  From William Deegan:

    - Fix Issue #3283 - Handle using --config=force in combination with Decider('MD5-timestamp').
      3.0.2 in fix for issue #2980 added that deciders can throw DeciderNeedsNode exception.
      The Configure logic directly calls the decider when using --config=force but wasn't handling
      that exception.  This would yield minimally configure tests using TryLink() not running and
      leaving TypeError Nonetype exception in config.log
    - Fix Issue #3303 - Handle --config=force overwriting the Environment passed into Configure()'s
      Decider and not clearing it when the configure context is completed.
    - Add default paths for yacc tool on windows to include cygwin, mingw, and chocolatey
    - Fix issue #2799 - Fix mingw tool to respect SHCCCOMSTR, SHLINKCOMSTR and LDMODULECOMSTR
    - Fix Issue #3329 - Add support for MS SDK V10.0A (which is commonly installed with VS2017)
    - Fix Issue #3333 - Add support for finding vswhere under 32 bit windows installs.

  From Maciej Kumorek:
    - Update the MSVC tool to include the nologo flag by default in RCFLAGS

From Daniel Moody:
    - Change the default for AppendENVPath to delete_existing=0, so path
      order will not be changed, unless explicitly set (Issue #3276)
    - Fixed bug which threw error when running SCons on windows system with no MSVC installed.
    - Update link tool to convert target to node before accessing node member
    - Update mingw tool to remove MSVC like nologo CCFLAG
    - Add default paths for lex tool on windows to include cygwin, mingw, and chocolatey
    - Add lex construction variable LEXUNISTD for turning off unix headers on windows
    - Update lex tool to use win_flex on windows if available

  From Mats Wichmann:
    - Quiet open file ResourceWarnings on Python >= 3.6 caused by
      not using a context manager around Popen.stdout
    - Add the textfile tool to the default tool list
    - Fix syntax on is/is not clauses: should not use with a literal
    - Properly retrieve exit code when catching SystemExit
    - scons-time now uses context managers around file opens
    - Fix regex patterns that were not specified as raw strings

  From Bernhard M. Wiedemann:
    - Do not store build host+user name if reproducible builds are wanted


RELEASE 3.0.4 - Mon, 20 Jan 2019 22:49:27 +0000

  From Mats Wichmann:
    - Improve finding of Microsoft compiler: add a 'products' wildcard
      in case 2017 Build Tools only is installed as it is considered a separate
      product from the default Visual Studio
    - Add TEMPFILESUFFIX to allow a customizable filename extension, as
      described in the patch attached to issue #2431.
    - scons.py and sconsign.py stopped working if script called as a symlink
      to location in scons-local location.
    - Fix issue running scons using a symlink to scons.py in an scons-local dir
    - Doc updates around Default(), and the various *TARGETS variables.

  From Daniel Moody:
    - Improved support for VC14.1 and Visual Studio 2017, as well as arm and arm64 targets.
      Issues #3268 & Issue #3222
    - Initial support for ARM targets with Visual Studio 2017 - Issue #3182 (You must set TARGET_ARCH for this to work)
    - Update TempFileMunge class to use PRINT_CMD_LINE_FUNC

  From Tobias Herzog
    - Enhance cpp scanner regex logic to detect if/elif expressions without whitespaces but
      parenthesis like "#if(defined FOO)" or "#elif!(BAR)" correctly.


RELEASE 3.0.3 - Mon, 07 Jan 2019 20:05:22 -0400
  NOTE: 3.0.2 release was dropped because there was a packaging bug. Please consider all 3.0.2
        content.

  From William Deegan:
    - Fixes to packaging logic.  Ensuring the SCons.Tool.clangCommon module is added
      to the release packages.
    - Modify scons.bat script to check for scons python script without .py extension if no file
      scons.py exists. This enables an all platform wheel to work.

  From Mats Wichmann:
    - Update doc examples to work with Python 3.5+:  map() now returns an iterable instead of a list.


RELEASE 3.0.2 - Mon, 31 Dec 2018 16:00:12 -0700

  From Bernard Blackham:
    - Fixed handling of side-effects in task master (fixes #3013).

  From William Deegan:
    - Remove long deprecated SCons.Options code and tests.  This removes BoolOption,EnumOption,
      ListOption,PackageOption, and PathOption which have been replaced by *Variable() many years ago.
    - Re-Enable parallel SCons (-j) when running via Pypy
    - Move SCons test framework files to testing/framework and remove all references to QMtest.
      QMTest has not been used by SCons for some time now.
    - Updated logic for mingw and clang on win32 to search default tool install paths if not
      found in normal SCons PATH.  If the user specifies PATH or tool specific paths they
      will be used and the default paths below will be ignored.
      - Default path for clang/clangxx : C:\Program Files\LLVM\bin
      - Default path for mingw         : C:\MinGW\bin and/or  C:\mingw-w64\*\mingw64\bin
      - Key program to locate mingw    : mingw32-make (as the gcc with mingw prefix has no fixed name)
    - Fixed issue causing stack trace when python Action function contains a unicode string when being
      run with Python 2.7
    - Add alternate path to QT install for Centos in qt tool: /usr/lib64/qt-3.3/bin
    - Fix Java tools to search reasonable default paths for Win32, Linux, macOS.  Add required paths
      for swig and java native interface to JAVAINCLUDES.  You should add these to your CPPPATH if you need
      to compile with them.  This handles spaces in paths in default Java paths on windows.
    - Added more java paths to match install for Centos 7 of openjdk
    - Fix new logic which populates JAVAINCLUDES to handle the case where javac is not found.
    - Fix GH Issue #2580 - # in FRAMEWORKPATH doesn't get properly expanded. The # is left in the
      command line.
    - Fix issue #2980 with credit to Piotr Bartosik (and William Blevins).  This is an issue where using
      TimeStamp-MD5 Decider and CacheDir can yield incorrect md5's being written into the .sconsign.
      The difference between Piotr Bartosik's patch and the current code is that the more complicated
      creation of file to csig map is only done when the count of children for the current node doesn't
      match the previous count which is loaded from the sconsign.
    - Fix issue # 3106 MSVC if using MSVC_BATCH and target dir had a space would fail due to quirk in
      MSVC's handling of escaped targetdirs when batch compiling.
    - Fix GH Issue #3141 unicode string in a TryAction() with python 2.7 crashes.
    - Fix GH Issue #3212 - Use of Py3 and CacheDir + Configure's TryCompile (or likely and Python Value Nodes)
      yielded trying to combine strings and bytes which threw exception.
    - Fix GH Issue #3225 SCons.Util.Flatten() doesn't handle MappingView's produced by dictionary as return
      values from dict().{items(), keys(), values()}.
    - Fix GH Issue #3241 - Properly support versioned shared libraries for MacOS.  We've also introduced two
      new env variables APPLELINK_CURRENT_VERSION and APPLELINK_COMPATIBILITY_VERSION which will specify
      what is passed to the linkers -current_version and -compatibility_version flags.  If not specified
      they will be derived from SHLIBVERSION as such:
      - APPLELINK_CURRENT_VERSION = SHLIBVERSION
      - APPLELINK_COMPATIBILITY_VERSION = all but the last digit in SHLIBVERSION with .0 appended.
      Note that the values of the above will be validated. Valid format for either APPLELINK variable is
      X[.Y[.Z]] where 0 <= X <= 65535, 0 <= Y <= 255, 0 <= Z <= 255.
      The new variables have been added to the documents and should show up in user guide and manpage.
    - Fix GH Issue #3136 no longer wrap io.{BufferedReader,BufferedWriter,BufferedRWPair,BufferedRandom,TextIOWrapper
      with logic to set HANDLE_FLAG_INHERIT flag on the file handle.  Python 3.4+ automatically sets this according
      to Python docs: https://docs.python.org/3/library/os.html#fd-inheritance

  From Ray Donnelly:
    - Fix the PATH created by scons.bat (and other .bat files) to provide a normalized
      PATH.  Some pythons in the 3.6 series are no longer able to handle paths which
      have ".." in them and end up crashing.  This is done by cd'ing into the directory
      we want to add to the path and then using %CD% to give us the normalized directory
      See bug filed under Python 3.6: https://bugs.python.org/issue32457.
      Note: On Win32 PATH's which have not been normalized may cause undefined behavior
      by other executables being run by SCons (or any subprocesses of executables being run by SCons).
      Resolving this issue should eliminate that possibility going forward.

  From Andrew Featherstone
    - Removed unused --warn options from the man page and source code.

  From Arda Fu
    - Fix cpp scanner regex logic to treat ifndef for py3.5+. Previously it was
      not properly differentiating between if, ifdef, and ifndef.

  From Philipp Maierhöfer
    - Added a __hash__ method to the class SCons.Subst.Literal. Required when substituting Literal
      objects when SCons runs with Python 3.
    - Added missing FORTRANMODDIRPREFIX to the gfortran tool.

  From Matthew Marinets:
    - Fixed an issue that caused the Java emitter to incorrectly parse arguments to constructors that
      implemented a class.

  From Fredrik Medley:
    - Fix exception when printing of EnviromentError messages.
      Specifically, this fixes error reporting of the race condition when
      initializing the cache which error previously was hidden.

  From Daniel Moody:
    - Updated Jar builder to handle nodes and directories better
    - Updated Jar builder to flatten source list which could contain embedded lists
    - Removed some magic numbers from jar.py on behalf of Mats Wichmann (mats@linux.com)
    - Set the pickling protocal back to highest which was causing issues
      with variant dir tests. This will cause issues if reading sconsigns
      pickled with the previous lower protocol.
    - Updated swig to setup default paths for windows
    - Updated gettext tools to setup default paths for windows with Cygwin/MinGW setups
    - Add common location for default paths for cygwin and mingw in Platform modules
    - Updated YACC tool to work on windows with Cygwin/MinGW setups
    - Set the pickling protocal back to highest which was causing issues
      with variant dir tests. This will cause issues if reading sconsigns
      pickled with the previous lower protocol.
    - Updated FS.py to handle removal of splitunc function from python 3.7
    - Updated the vc.py to ignore MSVS versions where no compiler could be found

  From Gary Oberbrunner:
    - Fix bug when Installing multiple subdirs outside the source tree
    - fix to_str to handle None without raising exception
    - Fix -jN for python 3.7

  From Jonathon Reinhart:
    - Replace all instances of `int main()` in C code with `int main(void)`.
      Specifically, this fixes the test cases use by Configure.CheckCC() which
      would fail when using -Wstrict-prototypes.

  From Zachary Tessler:
    - Fix calculation of signatures for FunctionActions that contain list (or set,...)
      comprehensions whose expressions involve constant literals. Those constants had
      been ignored in signatures, so changing them did not cause targets to be rebuilt.

  From Paweł Tomulik:
    - In the testing framework, module TestCommon, fixed must_contain(),
      must_not_contain(), and related methods of TestCommon class to work with
      substrings located at zero offset.
    - Added virtualenv support. A new function Virtualenv() determines whether
      SCons runs in a virtualenv. The search PATH may also be extended to
      prefer executables from the current virtualenv over the ones provided by
      base environment. New option --enable-virtualenv provided to import some
      virtualenv-related variables to SCons and extend every env['ENV']['PATH']
      automatically. New option --ignore-virtualenv disables this. Two
      environment variables, SCONS_ENABLE_VIRTUALENV and
      SCONS_IGNORE_VIRTUALENV are supported for the same purpose.

  From Richard West:
    - Add SConstruct.py, Sconstruct.py, sconstruct.py to the search path for the root SConstruct file.
      Allows easier debugging within Visual Studio
    - Change setup.py to change the install directory (via  pip, or setup.py install) from scons-#.#.#
      to scons (Yielding <pythondir>/lib/scons/SCons/ instead of <pythondir>/lib/scons/SCons-#.#.#/).
      This changes SCons to better comply with normal Python installation practices.

  From Mats Wichmann:
    - Recognize new java 9, 10, 11 (as 9.0 and 10.0, 11.0)
    - Updated manpage scons.xml to fix a nested list problem
    - Updated doc terminiology: use prepend instead of append as appropriate
    - XML validity fixes from SConstruct.py change
    - Update wiki links to new github location
    - Update bug links to new github location
    - Make it easier for SConscript() call to fail on missing script.
      It was possible to call SCons.Warnings.warningAsException
      (not documented as a user API) to make all warnings fail. Now
      SConscript can take an optional must_exist flag which if true fails
      if the script does not exist.  Not failing on missing script is
      now considered deprecated, and the first instance will print a
      deprecation message.  It is now also possible to flip the scons
      behavior (which still defaults to warn, not fail) by calling
      SCons.Script.set_missing_sconscript_error, which is also not a
      documented interface at the moment.
    - Convert TestCmd.read to use with statement on open (quiets 17 py3 warnings)
    - Quiet py3 warning in UtilTests.py
    - Fix tests specifying octal constants for py3
    - Fix must_contain tests for py3
    - RPM package generation:
       - Fix supplying a build architecture
       - Disable auto debug package generation on certain rpmbuild versions
       - Adjust some tests to only supply build-id file on certain rpmbuild versions
       - Tests now use a file fixture for the repeated (trivial) main.c program.
       - Document and comment cleanup.
       - Added new Environment Value X_RPM_EXTRADEFS to supply custom settings
         to the specfile without adding specific logic for each one to scons.
    - The test for Python.h needed by swig tests is moved to get_python_platform
      so it does not have to be repeated in every test; picks up one failure
      which did not make the (previously needed) check. Windows version
      of get_python_platform needed some rework in case running in virtualenv.
    - If test opens os.devnull, register with atexit so file opens do not leak.
    - Fix bugs in Win32 process spawn logic to handle OSError exception correctly.
    - Use time.perf_counter instead of time.clock if it exists.
      time.clock deprecated since py3.3, due to remove in 3.8. deprecation
      warnings from py3.7 were failing a bunch of tests on Windows since they
      mess up expected stderr.
    - Prefer Py3's inspect.getfullargspec over deprecated inspect.getargspec.
      Switched to "new" (standard in Py2.7) usage of receiving a namedtuple -
      we were unpacking to a four-tuple, two of the items of which were unused;
      getfullargspec returns a named tuple with seven elements so it is a
      cleaner drop-in replacement using the namedtuple.
    - Updated the test-framework.rst documentation.
    - Remove obsoleted internal implementaiton of OrderedDict.
    - Test for tar packaging fixups
    - Stop using deprecated unittest asserts
    - messages in strip-install-dir test now os-neutral
    - Add xz compression format to packaging choices.
    - Syntax cleanups - trailing blanks, use "is" to compare with None, etc.
      Three uses of variables not defined are changed.
    - Some script changes in trying to find scons engine
    - Update (pep8) configure-cache script, add a --show option.
    - Fix for a couple of "what if tool not found" exceptions in framework.
    - Add Textfile/Substfile to default environment. (issue #3147)
    - sconsign: a couple of python3 fixes; be more tolerant of implicit
      entries which have no signatures; minor PEP8 changes.
    - Fix a couple of type mistakes (list-> string, filter type -> list)
    - Fix a couple of type mistakes in packaging tools: list-> string in msi,
      filter type -> list in ipk

  From Bernhard M. Wiedemann:
    - Update SCons' internal scons build logic to allow overriding build date
      with SOURCE_DATE_EPOCH for SCons itself.
    - Change the datestamps in SCons' docs and embedded in code use ISO 8601 format and UTC

  From Hao Wu
    - Typo in customized decider example in user guide
    - Replace usage of unittest.TestSuite with unittest.main() (fix #3113)

RELEASE 3.0.1 - Mon, 12 Nov 2017 15:31:33 -0700

  From Daniel Moody:
    - Jar can take multiple targets, and will make a duplicate jar from the sources for each target
    - Added some warnings in case the Jar builder makes an implicit target
    - Added Jar method and changed jar build to be more specific. Jar method will take in
      directories or classes as source. Added more tests to JAR to ensure the jar was
      packaged with the correct compiled class files.
    - Added a No result test case to handle bug which seems unrelated to java in the
      swig-dependencies.py test, more info here: http://scons.tigris.org/issues/show_bug.cgi?id=2907
    - Added a travis script to test on ubuntu trusty now that the project is on github
      so that Continuus Integration tests can be run automatically. It tests most case and considers
      no result a pass as well. Improving this script can install more dependincies allowing for more
      tests to be run.

  From Daniel Moody:
    - Updated the Jar Builder tool in Tool/__init__.py so that is doesn't force class files as
      sources, allowing directories to be passed, which was causing test/Java/JAR.py to fail.

  From William Deegan:
    - Fix issue where code in utility routine to_String_for_subst() had code whose result was never
      properly returned.
      (Found by: James Rinkevich https://pairlist4.pair.net/pipermail/scons-users/2017-October/006358.html )
    - Fixed Variables.GenerateHelpText() to now use the sort parameter. Due to incorrect 2to3 fixer changes
      8 years ago it was being used as a boolean parameter.  Now you can specify sort to be a callable, or boolean
      value. (True = normal sort). Manpage also updated.
    - Fixed Tool loading logic from exploding sys.path with many site_scons/site_tools prepended on py3.
    - Added additional output with time to process each SConscript file when using --debug=time.

  From Thomas Berg:
    - Fixed a regression in scons-3.0.0 where "from __future__ import print_function" was imposed
      on the scope where SConstruct is executed, breaking existing builds using PY 2.7.

  From William Deegan:
    - Fix broken subst logic where a string with "$$(abc)" was being treated as "$(abc) and the
      logic for removing the signature escapes was then failing because there was no closing "$)".
      This was introduced by a pull request to allow recursive variable evaluations to yield a string
      such as "$( $( some stuff $) $)".

  From Zachary Tessler:
    - Fix incorrect warning for repeated identical builder calls that use overrides


RELEASE 3.0.0 - Mon, 18 Sep 2017 08:32:04 -0700

NOTE: This is a major release.  You should expect that some targets may rebuild when upgrading.
Significant changes in some python action signatures. Also switching between PY 2.7 and PY 3.5, 3.6
will cause rebuilds.


  From William Blevins:
    - Updated D language scanner support to latest: 2.071.1. (PR #1924)
      https://dlang.org/spec/module.html accessed 11 August 2016
      - Enhancements:
        - Added support for selective imports: "import A : B, C;" -> A
        - Added support for renamed imports. "import B = A;" -> A
        - Supports valid combinations: "import A, B, CCC = C, DDD = D : EEE = FFF;" -> A, B, C, D
      - Notes:
        - May find new (previously missed) Dlang dependencies.
        - May cause rebuild after upgrade due to dependency changes.
    - Updated Fortran-related tests to pass under GCC 5/6.
    - Fixed SCons.Tool.Packaging.rpm.package source nondeterminism across builds.

  From William Deegan:
    - Removed deprecated tools CVS, Perforce, BitKeeper, RCS, SCCS, Subversion.
    - Removed deprecated module SCons.Sig
    - Added prioritized list of xsltproc tools to docbook. The order will now be as
      follows: xsltproc, saxon, saxon-xslt, xalan  (with first being highest priority, first
      tool found is used)
    - Fixed MSVSProject example code (http://scons.tigris.org/issues/show_bug.cgi?id=2979)
    - Defined MS SDK 10.0 and Changed VS 2015 to use SDK 10.0
    - Changes to Action Function and Action Class signiture creation.  NOTE: This will cause rebuilds
      for many builds when upgrading to SCons 3.0
    - Fixed Bug #3027 - "Cross Compiling issue: cannot override ranlib"
    - Fixed Bug #3020 - "Download link in user guide wrong. python setup.py install --version-lib broken"
    - Fixed Bug #2486 - Added SetOption('silent',True) - Previously this value was not allowed to be set.
    - Fixed Bug #3040 - Non-unicode character in CHANGES.txt
    - Fixed Bug #2622 - AlwaysBuild + MSVC regression.
    - Fixed Bug #3025 - (Credit to Florian : User flow86 on tigris) - Fix typo JAVACLASSSUFIX should have been
                        JAVACLASSSUFFIX


  From Ibrahim Esmat:
    - Added the capability to build Windows Store Compatible libraries that can be used
      with Universal Windows Platform (UWP) Apps and published to the store

  From Daniel Holth:
    - Add basic support for PyPy (by deleting __slots__ from Node with a
      metaclass on PyPy); wrap most-used open() calls in 'with' statements to
      avoid too many open files.
    - Add __main__.py for `python -m SCons` in case it is on PYTHONPATH.
    - Always use highest available pickle protocol for efficiency.
    - Remove unused command line fallback for the zip tool.

  From Gaurav Juvekar:
    - Fix issue #2832: Expand construction variables in 'chdir' argument of builders. (PR #463)
    - Fix issue #2910: Make --tree=all handle Unicode. (PR #427)
    - Fix issue #2788: Fix typo in documentation example for sconf. (PR #388)

  From Alexey Klimkin:
    - Use memoization to optimize PATH evaluation across all dependencies per
      node. (PR #345)
    - Use set() where it is applicable (PR #344)

  From M. Limber:
    - Fixed msvs.py for Visual Studio Express editions that would report
      "Error  : ValueError: invalid literal for float(): 10.0Exp".

  From Rick Lupton:
    - Update LaTeX scanner to understand \import and related commands

  From Steve Robinson:
    - Add support for Visual Studio 2017.  This support requires vswhere.exe a helper
      tool installed with newer installs of 2017. SCons expects it to be located at
      "C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe"
      It can be downloaded separately at
      https://github.com/Microsoft/vswhere

  From Tom Tanner:
    - Allow nested $( ... $) sections

  From Paweł Tomulik:
    - Fixed the issue with LDMODULEVERSIONFLAGS reported by Tim Jenness
      (https://pairlist4.pair.net/pipermail/scons-users/2016-May/004893.html).
      An error was causing "-Wl,Bsymbolic" being added to linker's command-line
      even when there was no specified value in LDMODULEVERSION and thus no
      need for the flags to be specified.
    - Added LoadableModule to the list of global functions (DefaultEnvironment
      builders).

  From Manish Vachharajani:
    - Update debian rules, compat, and control to not use features
      deprecated or obsolete in later versions of debhelpers
    - Update python version to 2.7 in debian/control

  From Richard Viney:
    - Fixed PCHPDBFLAGS causing a deprecation warning on MSVC v8 and later when
      using PCHs and PDBs together.


  From Richard West:
    - Added nested / namespace tool support
    - Added a small fix to the python3 tool loader when loading a tool as a package
    - Added additional documentation to the user manual on using toolpaths with the environment
      This includes the use of sys.path to search for tools installed via pip or package managers
    - Added support for a PyPackageDir function for use with the toolpath

  From Russel Winder:
    - Reordered the default D tools from "dmd, gdc, ldc" to "dmd, ldc, gdc".
    - Add a ProgramAllAtOnce builder to the dmd, ldc, and gdc tools. (PR #448)
    - Remove a file name exception for very old Fedora LDC installation.
    - gdc can now handle building shared objects (tested for version 6.3.0).
    - Remove establishing the SharedLibrary builder in the dmd, ldc, and gdc
      tools, must now include the ar tool to get this builder as is required for
      other compiler tools.
    - Add clang and clang++ tools based on Paweł Tomulik's work.

RELEASE 2.5.1 - Mon, 03 Nov 2016 13:37:42 -0400

  From William Deegan:
    - Add scons-configure-cache.py to packaging. It was omitted

  From Alexey Klimkin:
    - Use memoization to optimize PATH evaluation across all dependencies per
      node. (PR #345)

RELEASE 2.5.0 - Mon, 09 Apr 2016 11:27:42 -0700

  From Dirk Baechle:
    - Removed a lot of compatibility methods and workarounds
      for Python versions < 2.7, in order to prepare the work
      towards a combined 2.7/3.x version. (PR #284)
      Also fixed the default arguments for the print_tree and
      render_tree methods. (PR #284, too)

  From William Blevins:
    - Added support for cross-language dependency scanning;
      SCons now respects scanner keys for implicit dependencies.
      - Notes for SCons users with heterogeneous systems.
        - May find new (previously missed) dependencies.
        - May cause rebuild after upgrade due to dependency changes.
        - May find new dependency errors (EG. cycles).
          - Discovered in some of the SCons QT tests.
    - Resolved missing cross-language dependencies for
      SWIG bindings (fixes #2264).
    - Corrected typo in User Guide for Scanner keyword. (PR #2959)
    - Install builder interacts with scanner found in SCANNERS differently.
      - Previous: Install builder recursively scanned implicit dependencies
        for scanners from SCANNER, but not for built-in (default) scanners.
      - Current: Install builder will not scan for implicit dependencies via
        either scanner source. This optimizes some Install builder behavior
        and brings orthogonality to Install builder scanning behavior.

  From William Deegan:
    - Add better messaging when two environments have
      different actions for the same target (Bug #2024)
    - Fix issue only with MSVC and Always build where targets
      marked AlwaysBuild wouldn't make it into CHANGED_SOURCES
      and thus yield an empty compile command line. (Bug #2622)
    - Fix posix platform escaping logic to properly handle paths
      with parens in them "()".  (Bug #2225)

  From Jakub Pola:
    - Intel Compiler 2016 (Linux/Mac) update for tool directories.

  From Adarsh Sanjeev:
    - Fix for issue #2494: Added string support for Chmod function.

  From Tom Tanner:
    - change cache to use 2 character subdirectories, rather than one character,
      so as not to give huge directories for large caches, a situation which
      causes issues for NFS.
      For existing caches, you will need to run the scons-configure-cache.py
      script to update them to the new format. You will get a warning every time
      you build until you co this.
    - Fix a bunch of unit tests on windows

RELEASE 2.4.1 - Mon, 07 Nov 2015 10:37:21 -0700

  From Arfrever Frehtes Taifersar Arahesis:
    - Fix for Bug # 2791 - Setup.py fails unnecessarily under Jython.

  From Dirk Baechle:
    - Fixed license of SVG titlepage files in the context of Debian
      packaging, such that they allow for commercial use too (#2985).

  From William Blevins:
    - InstallVersionedLib now available in the DefaultEnvironment context.
    - Improves orthogonality of use cases between different Install functions.

  From Carnë Draug:
    - Added new configure check, CheckProg, to check for
      existence of a program.

  From Andrew Featherstone:
    - Fix for issue #2840 - Fix for two environments specifying same target with different
      actions not throwing hard error. Instead SCons was incorrectly issuing a warning
      and continuing.

  From Hiroaki Itoh :
    - Add support `Microsoft Visual C++ Compiler for Python 2.7'
      Compiler can be obtained at: https://www.microsoft.com/en-us/download/details.aspx?id=44266

  From Florian Miedniak:
    - Fixed tigris issue #3011: Glob() excludes didn't work when used with VariantDir(duplicate=0)

  From William Roberts:
    - Fix bug 2831 and allow Help() text to be appended to AddOption() help.

  From Paweł Tomulik:
    - Reimplemented versioning for shared libraries, with the following effects
    - Fixed tigris issues #3001, #3006.
    - Fixed several other issues not reported to tigris, including:
      issues with versioned libraries in subdirectories with tricky names,
      issues with versioned libraries and variant directories,
      issue with soname not being injected to library when using D linkers,
    - Switched to direct symlinks instead of daisy-chained ones -- soname and
      development symlinks point directly to the versioned shared library now),
      for rationale see:
      https://www.debian.org/doc/debian-policy/ch-sharedlibs.html
      https://fedoraproject.org/wiki/Packaging:Guidelines#Devel_Packages
      https://bitbucket.org/scons/scons/pull-requests/247/new-versioned-libraries-gnulink-cyglink/diff#comment-10063929
    - New construction variables to allow override default behavior: SONAME,
      SHLIBVERSIONFLAGS, _SHLIBVERSIONFLAGS, SHLIBNOVERSIONSYMLINKS,
      LDMODULEVERSION, LDMODULEVERSIONFLAGS, _LDMODULEVERSIONFLAGS,
      LDMODULENOVERSIONSYMLINKS.
    - Changed logic used to configure the versioning machinery from
      platform-centric to linker-oriented.
    - The SHLIBVERSION/LDMODULEVERSION variables are no longer validated by
      SCons (more freedom to users).
    - InstallVersionedLib() doesn't use SHLIBVERSION anymore.
    - Enchanced docs for the library versioning stuff.
    - New tests for versioned libraries.
    - Library versioning is currently implemented for the following linker
      tools: 'cyglink', 'gnulink', 'sunlink'.
    - Fix to swig tool - pick-up 'swig', 'swig3.0' and 'swig2.0' (in order).
    - Fix to swig tool - respect env['SWIG'] provided by user.



RELEASE 2.4.0 - Mon, 21 Sep 2015 08:56:00 -0700

  From Dirk Baechle:
    - Switched several core classes to use "slots", to
      reduce the overall memory consumption in large
      projects (fixes #2180, #2178, #2198)
    - Memoizer counting uses decorators now, instead of
      the old metaclasses approach.

  From Andrew Featherstone
    - Fixed typo in SWIGPATH description

RELEASE 2.3.6 - Mon, 31 Jul 2015 14:35:03 -0700

  From Rob Smith:
    - Added support for Visual Studio 2015

RELEASE 2.3.5 - Mon, 17 Jun 2015 21:07:32 -0700

  From Stephen Pollard:
    - Documentation fixes for libraries.xml and
      builders-writing.xml (#2989 and #2990)

  From William Deegan:
    - Extended docs for InstallVersionedLib/SharedLibrary,
      and added SKIP_WIN_PACKAGES argument to build script
      bootstrap.py (PR #230, #3002).

  From William Blevins:
    - Fixed symlink support (PR #227, #2395).
    - Updated debug-count test case (PR #229).

  From Alexey Klimkin:
    - Fixed incomplete LIBS flattening and substitution in
      Program scanner(PR #205, #2954).

  From Dirk Baechle:
    - Added new method rentry_exists_on_disk to Node.FS (PR #193).

  From Russel Winder:
    - Fixed several D tests under the different OS.
    - Add support for f08 file extensions for Fortran 2008 code.

  From Anatoly Techtonik:
    - Show --config choices if no argument is specified (PR #202).
    - Fixed build crash when XML toolchain isn't installed, and
      activated compression for ZIP archives.

  From Alexandre Feblot:
    - Fix for VersionedSharedLibrary under 'sunos' platform.
    - Fixed dll link with precompiled headers on MSVC 2012
    - Added an 'exclude' parameter to Glob()

  From Laurent Marchelli:
    - Support for multiple cmdargs (one per variant) in VS project files.
    - Various improvements for TempFileMunge class.
    - Added an implementation for Visual Studio users files (PR #209).

  From Dan Pidcock:
    - Added support for the 'PlatformToolset' tag in VS project files (#2978).

  From James McCoy:
    - Added support for '-isystem' to ParseFlags.

RELEASE 2.3.4 - Mon, 27 Sep 2014 12:50:35 -0400

  From Bernhard Walle and Dirk Baechle:
    - Fixed the interactive mode, in connection with
      Configure contexts (#2971).

  From Anatoly Techtonik:
    - Fix EnsureSConsVersion warning when running packaged version

  From Russel Winder:
    - Fix D tools for building shared libraries

RELEASE 2.3.3 - Sun, 24 Aug 2014 21:08:33 -0400

  From Roland Stark:
    - Fixed false line length calculation in the TempFileMunge class (#2970).

  From Gary Oberbrunner:
    - Improve SWIG detection

  From Russel Winder:
    - Fix regression on Windows in D language update

  From Neal Becker and Stefan Zimmermann:
    - Python 3 port and compatibility

  From Anatoly Techtonik:
    - Do not fail on EnsureSConsVersion when running from checkout

  From Kendrick Boyd and Rob Managan:
    - Fixed the newglossary action to work with VariantDir (LaTeX).

  From Manuel Francisco Naranjo:
    - Added a default for the BUILDERS environment variable,
      to prevent not defined exception on a Clone().

  From Andrew Featherstone:
    - Added description of CheckTypeSize method (#1991).
    - Fixed handling of CPPDEFINE var in Append()
      for several list-dict combinations (#2900).

  From William Blevins:
    - Added test for Java derived-source dependency tree generation.
    - Added Copy Action symlink soft-copy support (#2395).
    - Various contributions to the documentation (UserGuide).

RELEASE 2.3.2

  From Dirk Baechle:
    - Update XML doc editor configuration
    - Fix: Allow varlist to be specified as list of strings for Actions (#2754)

  From veon on bitbucket:
    - Fixed handling of nested ifs in CPP scanner PreProcessor class.

  From Shane Gannon:
    - Support for Visual Studio 2013 (12.0)

  From Michael Haubenwallner:
    - Respect user's CC/CXX values; don't always overwrite in generate()
    - Delegate linker Tool.exists() to CC/CXX Tool.exists().

  From Rob Managan:
    - Updated the TeX builder to support use of the -synctex=1
      option and the files it creates.
    - Updated the TeX builder to correctly clean auxiliary files when
      the biblatex package is used.

  From Gary Oberbrunner:
    - get default RPM architecture more robustly when building RPMs

  From Amir Szekely:
    - Fixed NoClean() for multi-target builders (#2353).

  From Paweł Tomulik:
    - Fix SConf tests that write output

  From Russel Winder:
    - Revamp of the D language support. Tools for DMD, GDC and LDC provided
      and integrated with the C and C++ linking. NOTE: This is only tested
      with D v2. Support for D v1 is now deprecated.

  From Anatoly Techtonik:
    - Several improvements for running scons.py from source:
      * engine files form source directory take priority over all other
        importable versions
      * message about scons.py running from source is removed to fix tests
        that were failing because of this extra line in the output
      * error message when SCons import fails now lists lookup paths
    - Remove support for QMTest harness from runtest.py
    - Remove RPM and m4 from default tools on Windows
    - BitKeeper, CVS, Perforce, RCS, SCCS are deprecated from default
      tools and will be removed in future SCons versions to speed up
      SCons initialization (it will still be possible to use these tools
      explicitly)

  From Sye van der Veen:
    - Support for Visual Studio 12.0Exp, and fixes for earlier MSVS
      versions.


RELEASE 2.3.1

  From Andrew Featherstone:
    - Added support for EPUB output format to the DocBook tool.

  From Tom Tanner:
    - Stop leaking file handles to subprocesses by switching to using subprocess
      always.
    - Allow multiple options to be specified with --debug=a,b,c
    - Add support for a readonly cache (--cache-readonly)
    - Always print stats if requested
    - Generally try harder to print out a message on build errors
    - Adds a switch to warn on missing targets
    - Add Pseudo command to mark targets which should not exist after
      they are built.

  From Bogdan Tenea:
    - Check for 8.3 filenames on cygwin as well as win32 to make variant_dir work properly.

  From Alexandre Feblot:
    - Make sure SharedLibrary depends on all dependent libs (by depending on SHLINKCOM)

  From Stefan Sperling:
    - Fixed the setup of linker flags for a versioned SharedLibrary
      under OpenBSD (#2916).

  From Antonio Cavallo:
    - Improve error if Visual Studio bat file not found.

  From Manuel Francisco Naranjo:
    - Allow Subst.Literal string objects to be compared with each other,
      so they work better in AddUnique() and Remove().

  From David Rothenberger:
    - Added cyglink linker that uses Cygwin naming conventions for
      shared libraries and automatically generates import libraries.

  From Dirk Baechle:
    - Update bootstrap.py so it can be used from any dir, to run
      SCons from a source (non-installed) dir.
    - Count statistics of instances are now collected only when
      the --debug=count command-line option is used (#2922).
    - Added release_target_info() to File nodes, which helps to
      reduce memory consumption in clean builds and update runs
      of large projects.
    - Fixed the handling of long options in the command-line
      parsing (#2929).
    - Fixed misspelled variable in intelc.py (#2928).

  From Gary Oberbrunner:
    - Test harness: fail_test() can now print a message to help debugging.

  From Anatoly Techtonik:
    - Require rpmbuild when building SCons package.
    - Print full stack on certain errors, for debugging.
    - Improve documentation for Textfile builder.

  From William Deegan:
    - VS2012 & VS2010 Resolve initialization issues by adding path to reg.exe
      in shell used to run batch files.
    - MSVC Support fixed defaulting TARGET_ARCH to HOST_ARCH. It should be
      None if not explicitly set.
    - MSVC Fixed issue where if more than one Architectures compilers are
      detected, it would take the last one found, and not the first.

  From Philipp Kraus:
    - Added optional ZIPROOT to Zip tool.

  From Dirk Baechle:
    - Replaced old SGML-based documentation toolchain with a more modern
      approach, that also requires less external dependencies (programs and
      Python packages). Added a customized Docbook XSD for strict validation of
      all input XML files.

  From Luca Falavigna:
    - Fixed spelling errors in MAN pages (#2897).

  From Michael McDougall:
    - Fixed description of ignore_case for EnumVariable in the
      MAN page (#2774).

RELEASE 2.3.0 - Mon, 02 Mar 2013 13:22:29 -0400

  From Anatoly Techtonik:
    - Added ability to run scripts/scons.py directly from source checkout
    - Hide deprecated --debug={dtree,stree,tree} from --help output
    - Error messages from option parser now include hints about valid choices
    - Cleaned up some Python 1.5 and pre-2.3 code, so don't expect SCons
      to run on anything less than Python 2.4 anymore
    - Several fixes for runtest.py:
      * exit with an error if no tests were found
      * removed --noqmtest option - this behavior is by default
      * replaced `-o FILE --xml` combination with `--xml FILE`
      * changed `-o, --output FILE` option to capture stdout/stderr output
        from runtest.py
    - Remove os_spawnv_fix.diff patch required to enable parallel builds
      support prior to Python 2.2

  From Juan Lang:
    - Fix WiX Tool to use .wixobj rather than .wxiobj for compiler output
    - Support building with WiX releases after 2.0

  From Alexey Klimkin:
    - Fix nested LIBPATH expansion by flattening sequences in subst_path.

  From eyan on Bitbucket:
    - Print target name with command execution time with --debug=time

  From Thomas Berg and Evgeny Podjachev:
    - Fix subprocess spawning on Windows.  Work around a Windows
      bug that can crash python occasionally when using -jN. (#2449)

  From Dirk Baechle:
    - Updated test framework to support dir and file fixtures and
      added ability to test external (out-of-tree) tools (#2862).
      See doc in QMTest/test-framework.rst.
    - Fixed several errors in the test suite (Java paths, MSVS version
      detection, Tool import), additionally
      * provided MinGW command-line support for the CXX, AS and
        Fortran tests,
      * refactored the detection of the gcc version and the according
        Fortran startup library,
      * provided a new module rpmutils.py, wrapping the RPM naming rules
        for target files and further hardware-dependent info (compatibility,
        compiler flags, ...),
      * added new test methods must_exist_one_of() and
        must_not_exist_any_of() and
      * removed Aegis support from runtest.py. (#2872)

  From Gary Oberbrunner:
    - Add -jN support to runtest.py to run tests in parallel
    - Add MSVC10 and MSVC11 support to get_output low-level bat script runner.
    - Fix MSVS solution generation for VS11, and fixed tests.

  From Rob Managan:
    - Updated the TeX builder to support the \newglossary command
      in LaTeX's glossaries package and the files it creates.
    - Improve support for new versions of biblatex in the TeX builder
      so biber is called automatically if biblatex requires it.
    - Add SHLIBVERSION as an option that tells SharedLibrary to build
      a versioned shared library and create the required symlinks.
      Add builder InstallVersionedLib to create the required symlinks
      installing a versioned shared library.

RELEASE 2.2.0 - Mon, 05 Aug 2012 15:37:48 +0000

  From dubcanada on Bitbucket:
    - Fix 32-bit Visual Express C++ on 64-bit Windows (generate 32-bit code)

  From Paweł Tomulik:
    - Added gettext toolset
    - Fixed FindSourceFiles to find final sources (leaf nodes).

  From Greg Ward:
    - Allow Node objects in Java path (#2825)

  From Joshua Hughes:
    - Make Windows not redefine builtin file as un-inheritable (#2857)
    - Fix WINDOWS_INSERT_DEF on MinGW (Windows) (#2856)

  From smallbub on Bitbucket:
    - Fix LINKCOMSTR, SHLINKCOMSTR, and LDMODULECOMSTR on Windows (#2833).

  From Mortoray:
    - Make -s (silent mode) be silent about entering subdirs (#2976).
    - Fix cloning of builders when cloning environment (#2821).

  From Gary Oberbrunner:
    - Show valid Visual Studio architectures in error message
       when user passes invalid arch.

  From Alexey Petruchik:
    - Support for Microsoft Visual Studio 11 (both using it
      and generating MSVS11 solution files).

  From Alexey Klimkin:
    - Fixed the Taskmaster, curing spurious build failures in
      multi-threaded runs (#2720).

  From Dirk Baechle:
    - Improved documentation of command-line variables (#2809).
    - Fixed scons-doc.py to properly convert main XML files (#2812).

  From Rob Managan:
    - Updated the TeX builder to support LaTeX's multibib package.
    - Updated the TeX builder to support LaTeX's biblatex package.
    - Added support for using biber instead of bibtex by setting
      env['BIBTEX'] = 'biber'

  From Arve Knudsen:
    - Test for FORTRANPPFILESUFFIXES (#2129).


RELEASE 2.1.0 - Mon, 09 Sep 2011 20:54:57 -0700

  From Anton Lazarev:
    - Fix Windows resource compiler scanner to accept DOS line endings.

  From Matthias:
    - Update MSVS documents to remove note indicating that only one
      project is currently supported per solution file.

  From Grzegorz Bizoń:
    - Fix long compile lines in batch mode by using TEMPFILE
    - Fix MSVC_BATCH=False (was treating it as true)

  From Justin Gullingsrud:
    - support -std=c++0x and related CXXFLAGS in pkgconfig (ParseFlags)

  From Vincent Beffara:
    - Support -dylib_file in pkgconfig (ParseFlags)

  From Gary Oberbrunner and Sohail Somani:
    - new construction variable WINDOWS_EMBED_MANIFEST to automatically
      embed manifests in Windows EXEs and DLLs.

  From Gary Oberbrunner:
    - Fix Visual Studio project generation when CPPPATH contains Dir nodes
    - Ensure Visual Studio project is regenerated when CPPPATH or CPPDEFINES change
    - Fix unicode error when using non-ASCII filenames with Copy or Install
    - Put RPATH in LINKCOM rather than LINKFLAGS so resetting
      LINKFLAGS doesn't kill RPATH
    - Fix precompiled headers on Windows when variant dir name has spaces.
    - Adding None to an Action no longer fails (just returns original action)
    - New --debug=prepare option to show each target as it's being
      prepared, whether or not anything needs to be done for it.
    - New debug option --debug=duplicate to print a line for each
      unlink/relink (or copy) of a variant file from its source file.
    - Improve error message for EnumVariables to show legal values.
    - Fix Intel compiler to sort versions >9 correctly (esp. on Linux)
    - Fix Install() when the source and target are directories and the
      target directory exists.

  From David Garcia Garzon:
    - Fix Delete to be able to delete broken symlinks and dir
      symlinks.

  From Imran Fanaswala and Robert Lehr:
    - Handle .output file generated by bison/yacc properly. Cleaning it
      when necessary.

  From Antoine Dechaume:
    - Handle SWIG file where there is whitespace after the module name
      properly. Previously the generated files would include
      the whitespace.

  From Dmitry R.:
    - Handle Environment in case __semi_deepcopy is None

  From Benoit Belley:

    - Much improved support for Windows UNC paths (\\SERVERNAME).

  From Jean-Baptiste Lab:

    - Fix problems with appending CPPDEFINES that contain
      dictionaries, and related issues with Parse/MergeFlags and
      CPPDEFINES.

  From Allen Weeks:

    - Fix for an issue with implicit-cache with multiple targets
      when dependencies are removed on disk.

  From Evgeny Podjachev and Alexey Petruchick:

    - Support generation of Microsoft Visual Studio 2008 (9.0)
      and 2010 (10.0) project and solution files.

  From Ken Deeter:

    - Fix a problem when FS Entries which are actually Dirs have builders.

  From Luca Falavigna:

    - Support Fortran 03

  From Gary Oberbrunner:

    - Print the path to the SCons package in scons --version

  From Jean-Fran�ois Colson:

    - Improve Microsoft Visual Studio Solution generation, and fix
      various errors in the generated solutions especially when using
      MSVS_SCC_PROVIDER, and when generating multiple projects.  The
      construction variable MSVS_SCC_PROJECT_BASE_PATH, which never
      worked properly, is removed.  Users can use the new variable
      MSVS_SCC_CONNECTION_ROOT instead if desired.

  From Anatoly Techtonik:

    - Use subprocess in bootstrap.py instead of os.execve to avoid
      losing output control on Windows (http://bugs.python.org/issue9148)

    - Revert patch for adding SCons to App Paths, because standard cmd
      shell doesn't search there. This is confusing, because `scons` can
      be executed from explorer, but fail to start from console.

    - Fix broken installation with easy_install on Windows (issue #2051)
      SCons traditionally installed in a way that allowed to run multiple
      versions side by side. This custom logic was incompatible with
      easy_install way of doing things.

    - Use epydoc module for generating API docs in HTML if command line
      utility is not found in PATH. Actual for Windows.

  From Alexander Goomenyuk:

    - Add .sx to assembly source scanner list so .sx files
      get their header file dependencies detected.

  From Arve Knudsen:

    - Set module metadata when loading site_scons/site_init.py
      so it is treated as a proper module; __doc__, __file__ and
      __name__ now refer to the site_init.py file.

  From Russel Winder:

    - Users Guide updates explaining that Tools can be packages as
      well as python modules.

  From Gary Oberbrunner:

    - New systemwide and per-user site_scons dirs.

  From Dirk Baechle:

    - XML fixes in User's Guide.
    - Fixed the detection of 'jar' and 'rmic' during
      the initialization of the respective Tools (#2730).
    - Improved docs for custom Decider functions and
      custom Scanner objects (#2711, #2713).
    - Corrected SWIG module names for generated *.i files (#2707).

  From Joe Zuntz:

    - Fixed a case-sensitivity problem with Fortran modules.

  From Bauke Conijn:

    - Added Users Guide example for auto-generated source code

  From Steven Knight:

    - Fix explicit dependencies (Depends()) on Nodes that don't have
      attached Builders.

    - Fix use of the global Alias() function with command actions.

  From Matt Hughes:

    - Fix the ability to append to default $*FLAGS values (which are
      implemented as CLVar instances) in a copied construction environment
      without affecting the original construction environment's value.

  From Rob Managan:

    - Updated the TeX command strings to include a /D on Windows in
      case the new directory is on a different drive letter.

    - Fixed the LaTeX scanner so dependencies are found in commands that
      are broken across lines with a comment or have embedded spaces.

    - The TeX builders should now work with tex files that are generated
      by another program. Thanks to Hans-Martin von Gaudecker for
      isolating the cause of this bug.

    - Added support for INDEXSTYLE environment variable so makeindex can
      find style files.

    - Added support for the bibunits package so we call bibtex on all
      the bu*.aux files.

    - Add support of finding path information on OSX for TeX applications
      MacPorts and Fink paths need to be added by the user

  From Russel Winder:

    - Add support for DMD version 2 (the phobos2 library).

  From William Deegan:

    - Add initial support for VS/VC 2010 (express and non-express versions)
    - Remove warning for not finding MS VC/VS install.
      "scons: warning: No version of Visual Studio compiler found
        - C/C++ compilers most likely not set correctly"
    - Add support for Linux 3.0


RELEASE 2.0.1 - Mon, 15 Aug 2010 15:46:32 -0700

  From Dirk Baechle:

    - Fix XML in documentation.

  From Joe Zuntz:

    - Fixed a case-sensitivity problem with Fortran modules.

  From Bauke Conijn:

    - Added Users Guide example for auto-generated source code

  From Steven Knight:

    - Fix explicit dependencies (Depends()) on Nodes that don't have
      attached Builders.

  From Matt Hughes:

    - Fix the ability to append to default $*FLAGS values (which are
      implemented as CLVar instances) in a copied construction environment
      without affecting the original construction environment's value.

  From Rob Managan:

    - Updated the TeX command strings to include a /D on Windows in
      case the new directory is on a different drive letter.

    - Fixed the LaTeX scanner so dependencies are found in commands that
      are broken across lines with a comment or have embedded spaces.


RELEASE 2.0.0.final.0 - Mon, 14 Jun 2010 22:01:37 -0700

  From Dirk Baechle:

    - Fix XML in documentation.

  From Steven Knight:

    - Provide forward compatibility for the 'profile' module.

    - Provide forward compatibility for the 'pickle' module.

    - Provide forward compatibility for the 'io' module.

    - Provide forward compatibility for the 'queue' module.

    - Provide forward compatibility for the 'collections' module.

    - Provide forward compatibility for the 'builtins' module.

    - Provide forward compatibility for 'sys.intern()'.

    - Convert to os.walk() from of os.path.walk().

    - Remove compatibility logic no longer needed.

    - Add a '-3' option to runtest to print 3.x incompatibility warnings.

    - Convert old-style classes into new-style classes.

    - Fix "Ignoring corrupt sconsign entry" warnings when building
      in a tree with a pre-2.0 .sconsign file.

    - Fix propagation from environment of VS*COMNTOOLS to resolve issues
      initializing MSVC/MSVS/SDK issues.

    - Handle detecting Visual C++ on Python versions with upper-case
      platform architectures like 'AMD64'.

  From W. Trevor King:

    - Revisions to README.

  From Greg Noel:

    - Apply numerous Python fixers to update code to more modern idioms.
      Find where fixers should be applied to code in test strings and
      apply the fixers there, too.

    - Write a fixer to convert string functions to string methods.

    - Modify the 'dict' fixer to be less conservative.

    - Modify the 'apply' fixer to handle more cases.

    - Create a modified 'types' fixer that converts types to 2.x
      equivalents rather than 3.x equivalents.

    - Write a 'division' fixer to highlight uses of the old-style
      division operator.  Correct usage where needed.

    - Add forward compatibility for the new 'memoryview' function
      (which replaces the 'buffer' function).

    - Add forward compatibility for the 'winreg' module.

    - Remove no-longer-needed 'platform' module.

    - Run tests with the '-3' option to Python 2.6 and clear up
      various reported incompatibilities.

    - Comb out code paths specialized to Pythons older than 2.4.

    - Update deprecation warnings; most now become mandatory.

    - Start deprecation cycle for BuildDir() and build_dir.

    - Start deprecation cycle for SourceCode() and related factories

    - Fixed a problem with is_Dict() not identifying some objects derived
      from UserDict.

  From Jim Randall:

    - Document the AllowSubstExceptions() function in the User's Guide.

  From William Deegan:

    - Migrate MSVC/MSVS/SDK improvements from 1.3 branch.


RELEASE 1.3.0 - Tue, 23 Mar 2010 21:44:19 -0400

  From Steven Knight:

    - Update man page and documentation.

  From William Deegan (plus minor patch from Gary Oberbrunner):

    - Support Visual Studio 8.0 Express

RELEASE 1.2.0.d20100306 - Sat, 06 Mar 2010 16:18:33 -0800

  From Luca Falavigna:

    - Fix typos in the man page.

  From Gottfried Ganssauge:

    - Support execution when SCons is installed via easy_install.

  From Steven Knight:

    - Make the messages for Configure checks of compilers consistent.

    - Issue an error message if a BUILDERS entry is not a Builder
      object or a callable wrapper.

  From Rob Managan:

    - Update tex builder to handle the case where a \input{foo}
      command tries to work with a directory named foo instead of the
      file foo.tex. The builder now ignores a directory and continues
      searching to find the correct file. Thanks to Lennart Sauerbeck
      for the test case and initial patch

      Also allow the \include of files in subdirectories when variantDir
      is used with duplicate=0. Previously latex would crash since
      the directory in which the .aux file is written was not created.
      Thanks to Stefan Hepp for finding this and part of the solution.

  From James Teh:
    - Patches to fix some issues using MS SDK V7.0

  From William Deegan:
    - Lots of testing and minor patches to handle mixed MS VC and SDK
      installations, as well as having only the SDK installed.


RELEASE 1.2.0.d20100117 - Sun, 17 Jan 2010 14:26:59 -0800

  From Jim Randall:
    - Fixed temp filename race condition on Windows with long cmd lines.

  From David Cournapeau:
    - Fixed tryRun when sconf directory is in a variant dir.
    - Do not add -fPIC for ifort tool on non-posix platforms (darwin and
      windows).
    - Fix bug 2294 (spurious CheckCC failures).
    - Fix SCons bootstrap process on windows 64 (wrong wininst name)

  From William Deegan:
    - Final merge from vs_revamp branch to main

    - Added definition and usage of HOST_OS, HOST_ARCH, TARGET_OS,
      TARGET_ARCH, currently only defined/used by Visual Studio
      Compilers. This will be rolled out to other platforms/tools
      in the future.

    - Add check for python >= 3.0.0 and exit gracefully.
      For 1.3 python >= 1.5.2 and < 3.0.0 are supported

    - Fix bug 1944 - Handle non-existent .i file in swig emitter, previously
      it would crash with an IOError exception. Now it will try to make an
      educated guess on the module name based on the filename.

  From Lukas Erlinghagen:

    - Have AddOption() remove variables from the list of
      seen-but-unknown variables (which are reported later).

    - An option name and aliases can now be specified as a tuple.

  From Hartmut Goebel:

    - Textfile builder.

  From Jared Grubb:

    - use "is/is not" in comparisons with None instead of "==" or "!=".

  From Jim Hunziker:

    - Avoid adding -gphobos to a command line multiple times
      when initializing use of the DMD compiler.

  From Jason Kenney:

    - Sugguested HOST/TARGET OS/ARCH separation.

  From Steven Knight:

    - Fix the -n option when used with VariantDir(duplicate=1)
      and the variant directory doesn't already exist.

    - Fix scanning of Unicode files for both UTF-16 endian flavors.

    - Fix a TypeError on #include of file names with Unicode characters.

    - Fix an exception if a null command-line argument is passed in.

    - Evaluate Requires() prerequisites before a Node's direct children
      (sources and dependencies).

  From Greg Noel:

    - Remove redundant __metaclass__ initializations in Environment.py.

    - Correct the documentation of text returned by sconf.Result().

    - Document that filenames with '.' as the first character are
      ignored by Glob() by default (matching UNIX glob semantics).

    - Fix SWIG testing infrastructure to work on Mac OS X.

    - Restructure a test that occasionally hung so that the test would
      detect when it was stuck and fail instead.

    - Substfile builder.

  From Gary Oberbrunner:

    - When reporting a target that SCons doesn't know how to make,
      specify whether it's a File, Dir, etc.

  From Ben Webb:

    - Fix use of $SWIGOUTDIR when generating Python wrappers.

    - Add $SWIGDIRECTORSUFFIX and $SWIGVERSION construction variables.

  From Rob Managan:

    - Add -recorder flag to Latex commands and updated internals to
      use the output to find files TeX creates. This allows the MiKTeX
      installations to find the created files

    - Notify user of Latex errors that would get buried in the
      Latex output

    - Remove LATEXSUFFIXES from environments that don't initialize Tex.

    - Add support for the glossaries package for glossaries and acronyms

    - Fix problem that pdftex, latex, and pdflatex tools by themselves did
      not create the actions for bibtex, makeindex,... by creating them
      and other environment settings in one routine called by all four
      tex tools.

    - Fix problem with filenames of sideeffects when the user changes
      the name of the output file from the latex default

    - Add scanning of files included in Latex by means of \lstinputlisting{}
      Patch from Stefan Hepp.

    - Change command line for epstopdf to use --outfile= instead of -o
      since this works on all platforms.
      Patch from Stefan Hepp.

    - Change scanner to properly search for included file from the
      directory of the main file instead of the file it is included from.
      Also update the emitter to add the .aux file associated with
      \include{filename} commands. This makes sure the required directories
      if any are created for variantdir cases.
      Half of the patch from Stefan Hepp.

RELEASE 1.2.0.d20090223 - Mon, 23 Feb 2009 08:41:06 -0800

  From Stanislav Baranov:

    - Make suffix-matching for scanners case-insensitive on Windows.

  From David Cournapeau:

    - Change the way SCons finds versions of Visual C/C++ and Visual
      Studio to find and use the Microsoft v*vars.bat files.

  From Robert P. J. Day:

    - User's Guide updates.

  From Dan Eaton:

    - Fix generation of Visual Studio 8 project files on x64 platforms.

  From Allan Erskine:

    - Set IncludeSearchPath and PreprocessorDefinitions in generated
      Visual Studio 8 project files, to help IntelliSense work.

  From Mateusz Gruca:

    - Fix deletion of broken symlinks by the --clean option.

  From Steven Knight:

    - Fix the error message when use of a non-existent drive on Windows
      is detected.

    - Add sources for files whose targets don't exist in $CHANGED_SOURCES.

    - Detect implicit dependencies on commands even when the command is
      quoted.

    - Fix interaction of $CHANGED_SOURCES with the --config=force option.

    - Fix finding #include files when the string contains escaped
      backslashes like "C:\\some\\include.h".

    - Pass $CCFLAGS to Visual C/C++ precompiled header compilation.

    - Remove unnecessary nested $( $) around $_LIBDIRFLAGS on link lines
      for the Microsoft linker, the OS/2 ilink linker and the Phar Lap
      linkloc linker.

    - Spell the Windows environment variables consistently "SystemDrive"
      and "SystemRoot" instead of "SYSTEMDRIVE" and "SYSTEMROOT".



RELEASE 1.2.0.d20090113 - Tue, 13 Jan 2009 02:50:30 -0800

  From Stanislav Baranov, Ted Johnson and Steven Knight:

    - Add support for batch compilation of Visual Studio C/C++ source
      files, controlled by a new $MSVC_BATCH construction variable.

  From Steven Knight:

    - Print the message, "scons: Build interrupted." on error output,
      not standard output.

    - Add a --warn=future-deprecated option for advance warnings about
      deprecated features that still have warnings hidden by default.

    - Fix use of $SOURCE and $SOURCES attributes when there are no
      sources specified in the Builder call.

    - Add support for new $CHANGED_SOURCES, $CHANGED_TARGETS,
      $UNCHANGED_SOURCES and $UNCHANGED_TARGETS variables.

    - Add general support for batch builds through new batch_key= and
      targets= keywords to Action object creation.

  From Arve Knudsen:

    - Make linker tools differentiate properly between SharedLibrary
      and LoadableModule.

    - Document TestCommon.shobj_prefix variable.

    - Support $SWIGOUTDIR values with spaces.

  From Rob Managan:

    - Don't automatically try to build .pdf graphics files for
      .eps files in \includegraphics{} calls in TeX/LaTeX files
      when building with the PDF builder (and thus using pdflatex).

  From Gary Oberbrunner:

    - Allow AppendENVPath() and PrependENVPath() to interpret '#'
      for paths relative to the top-level SConstruct directory.

    - Use the Borland ilink -e option to specify the output file name.

    - Document that the msvc Tool module uses $PCH, $PCHSTOP and $PDB.

    - Allow WINDOWS_INSERT_DEF=0 to disable --output-def when linking
      under MinGW.

  From Zia Sobhani:

    - Fix typos in the User's Guide.

  From Greg Spencer:

    - Support implicit dependency scanning of files encoded in utf-8
      and utf-16.

  From Roberto de Vecchi:

    - Remove $CCFLAGS from the the default definitions of $CXXFLAGS for
      Visual C/C++ and MIPSpro C++ on SGI so, they match other tools
      and avoid flag duplication on C++ command lines.

  From Ben Webb:

    - Handle quoted module names in SWIG source files.

    - Emit *_wrap.h when SWIG generates header file for directors

  From Matthew Wesley:

    - Copy file attributes so we identify, and can link a shared library
      from, shared object files in a Repository.



RELEASE 1.2.0 - Sat, 20 Dec 2008 22:47:29 -0800

  From Steven Knight:

    - Don't fail if can't import a _subprocess module on Windows.

    - Add warnings for use of the deprecated Options object.



RELEASE 1.1.0.d20081207 - Sun, 07 Dec 2008 19:17:23 -0800

  From Benoit Belley:

    - Improve the robustness of GetBuildFailures() by refactoring
      SCons exception handling (especially BuildError exceptions).

    - Have the --taskmastertrace= option print information about
      individual Task methods, not just the Taskmaster control flow.

    - Eliminate some spurious dependency cycles by being more aggressive
      about pruning pending children from the Taskmaster walk.

    - Suppress mistaken reports of a dependency cycle when a child
      left on the pending list is a single Node in EXECUTED state.

  From David Cournapeau:

    - Fix $FORTRANMODDIRPREFIX for the ifort (Intel Fortran) tool.

  From Brad Fitzpatrick:

    - Don't pre-generate an exception message (which will likely be
      ignored anyway) when an EntryProxy re-raises an AttributeError.

  From Jared Grubb:

    - Clean up coding style and white space in Node/FS.py.

    - Fix a typo in the documentation for $_CPPDEFFLAGS.

    - Issue 2401: Fix usage of comparisons with None.

  From Ludwig H�hne:

    - Handle Java inner classes declared within a method.

  From Steven Knight:

    - Fix label placement by the "scons-time.py func" subcommand
      when a profile value was close to (or equal to) 0.0.

    - Fix env.Append() and env.Prepend()'s ability to add a string to
      list-like variables like $CCFLAGS under Python 2.6.

    - Other Python2.6 portability:  don't use "as" (a Python 2.6 keyword).
      Don't use the deprecated Exception.message attribute.

    - Support using the -f option to search for a different top-level
      file name when walking up with the -D, -U or -u options.

    - Fix use of VariantDir when the -n option is used and doesn't,
      therefore, actually create the variant directory.

    - Fix a stack trace from the --debug=includes option when passed a
      static or shared library as an argument.

    - Speed up the internal find_file() function (used for searching
      CPPPATH, LIBPATH, etc.).

    - Add support for using the Python "in" keyword on construction
      environments (for example, if "CPPPATH" in env: ...).

    - Fix use of Glob() when a repository or source directory contains
      an in-memory Node without a corresponding on-disk file or directory.

    - Add a warning about future reservation of $CHANGED_SOURCES,
      $CHANGED_TARGETS, $UNCHANGED_SOURCES and $UNCHANGED_TARGETS.

    - Enable by default the existing warnings about setting the resource
      $SOURCE, $SOURCES, $TARGET and $TARGETS variable.

  From Rob Managan:

    - Scan for TeX files in the paths specified in the $TEXINPUTS
      construction variable and the $TEXINPUTS environment variable.

    - Configure the PDF() and PostScript() Builders as single_source so
      they know each source file generates a separate target file.

    - Add $EPSTOPDF, $EPSTOPDFFLAGS and $EPSTOPDFCOM

    - Add .tex as a valid extension for the PDF() builder.

    - Add regular expressions to find \input, \include and
      \includegraphics.

    - Support generating a .pdf file from a .eps source.

    - Recursive scan included input TeX files.

    - Handle requiring searched-for TeX input graphics files to have
      extensions (to avoid trying to build a .eps from itself, e.g.).

  From Greg Noel:

    - Make the Action() function handle positional parameters consistently.

    - Clarify use of Configure.CheckType().

    - Make the File.{Dir,Entry,File}() methods create their entries
      relative to the calling File's directory, not the SConscript
      directory.

    - Use the Python os.devnull variable to discard error output when
      looking for the $CC or $CXX version.

    - Mention LoadableModule() in the SharedLibrary() documentation.

  From Gary Oberbrunner:

    - Update the User's Guide to clarify use of the site_scons/
      directory and the site_init.py module.

    - Make env.AppendUnique() and env.PrependUnique remove duplicates
      within a passed-in list being added, too.

  From Randall Spangler:

    - Fix Glob() so an on-disk file or directory beginning with '#'
      doesn't throw an exception.



RELEASE 1.1.0 - Thu, 09 Oct 2008 08:33:47 -0700

  From Chris AtLee

    - Use the specified environment when checking for the GCC compiler
      version.

  From Ian P. Cardenas:

    - Fix Glob() polluting LIBPATH by returning copy of list

  From David Cournapeau:

    - Add CheckCC, CheckCXX, CheckSHCC and CheckSHCXX tests to
      configuration contexts.

    - Have the --profile= argument use the much faster cProfile module
      (if it's available in the running Python version).

    - Reorder MSVC compilation arguments so the /Fo is first.

  From Bill Deegan:

    - Add scanning Windows resource (.rc) files for implicit dependencies.

  From John Gozde:

    - When scanning for a #include file, don't use a directory that
      has the same name as the file.

  From Ralf W. Grosse-Kunstleve

    - Suppress error output when checking for the GCC compiler version.

  From Jared Grubb:

    - Fix VariantDir duplication of #included files in subdirectories.

  From Ludwig H�hne:

    - Reduce memory usage when a directory is used as a dependency of
      another Node (such as an Alias) by returning a concatenation
      of the children's signatures + names, not the children's contents,
      as the directory contents.

    - Raise AttributeError, not KeyError, when a Builder can't be found.

    - Invalidate cached Node information (such as the contenst returned
      by the get_contents() method) when calling actions with Execute().

    - Avoid object reference cycles from frame objects.

    - Reduce memory usage from Null Executor objects.

    - Compute MD5 checksums of large files without reading the entire
      file contents into memory.  Add a new --md5-chunksize option to
      control the size of each chunk read into memory.

  From Steven Knight:

    - Fix the ability of the add_src_builder() method to add a new
      source builder to any other builder.

    - Avoid an infinite loop on non-Windows systems trying to find the
      SCons library directory if the Python library directory does not
      begin with the string "python".

    - Search for the SCons library directory in "scons-local" (with
      no version number) after "scons-local-{VERSION}".

  From Rob Managan:

    - Fix the user's ability to interrupt the TeX build chain.

    - Fix the TeX builder's allowing the user to specify the target name,
      instead of always using its default output name based on the source.

    - Iterate building TeX output files until all warning are gone
      and the auxiliary files stop changing, or until we reach the
      (configurable) maximum number of retries.

    - Add TeX scanner support for:  glossaries, nomenclatures, lists of
      figures, lists of tables, hyperref and beamer.

    - Use the $BIBINPUTS, $BSTINPUTS, $TEXINPUTS and $TEXPICTS construction
      variables as search paths for the relevant types of input file.

    - Fix building TeX with VariantDir(duplicate=0) in effect.

    - Fix the LaTeX scanner to search for graphics on the TEXINPUTS path.

    - Have the PDFLaTeX scanner search for .gif files as well.

  From Greg Noel:

    - Fix typos and format bugs in the man page.

    - Add a first draft of a wrapper module for Python's subprocess
      module.

    - Refactor use of the SCons.compat module so other modules don't
      have to import it individually.

    - Add .sx as a suffix for assembly language files that use the
      C preprocessor.

  From Gary Oberbrunner:

    - Make Glob() sort the returned list of Files or Nodes
      to prevent spurious rebuilds.

    - Add a delete_existing keyword argument to the AppendENVPath()
      and PrependENVPath() Environment methods.

    - Add ability to use "$SOURCE" when specifying a target to a builder

  From Damyan Pepper:

    - Add a test case to verify that SConsignFile() files can be
      created in previously non-existent subdirectories.

  From Jim Randall:

    - Make the subdirectory in which the SConsignFile() file will
      live, if the subdirectory doesn't already exist.

  From Ali Tofigh:

    - Add a test to verify duplication of files in VariantDir subdirectories.



RELEASE 1.0.1 - Sat, 06 Sep 2008 07:29:34 -0700

  From Greg Noel:

    - Add a FindFile() section to the User's Guide.

    - Fix the FindFile() documentation in the man page.

    - Fix formatting errors in the Package() description in the man page.

    - Escape parentheses that appear within variable names when spawning
      command lines using os.system().



RELEASE 1.0.0 - XXX

  From Jared Grubb:

    - Clear the Node state when turning a generic Entry into a Dir.

  From Ludwig H�hne:

    - Fix sporadic output-order failures in test/GetBuildFailures/parallel.py.

    - Document the ParseDepends() function in the User's Guide.

  From khomenko:

    - Create a separate description and long_description for RPM packages.

  From Steven Knight:

    - Document the GetLaunchDir() function in the User's Guide.

    - Have the env.Execute() method print an error message if the
      executed command fails.

    - Add a script for creating a standard SCons development system on
      Ubuntu Hardy.  Rewrite subsidiary scripts for install Python and
      SCons versions in Python (from shell).

  From Greg Noel:

    - Handle yacc/bison on newer Mac OS X versions creating file.hpp,
      not file.cpp.h.

    - In RPCGEN tests, ignore stderr messages from older versions of
      rpcgen on some versions of Mac OS X.

    - Fix typos in man page descriptions of Tag() and Package(), and in
      the scons-time man page.

    - Fix documentation of SConf.CheckLibWithHeader and other SConf methods.

    - Update documentation of SConscript(variant_dir) usage.

    - Fix SWIG tests for (some versions of) Mac OS X.

  From Jonas Olsson:

    - Print the warning about -j on Windows being potentially unreliable if
      the pywin32 extensions are unavailable or lack file handle operations.

  From Jim Randall:

    - Fix the env.WhereIs() method to expand construction variables.

  From Rogier Schouten:

    - Enable building of shared libraries with the Bordand ilink32 linker.



RELEASE 1.0.0 - Sat, 09 Aug 2008 12:19:44 -0700

  From Luca Falavigna:

    - Fix SCons man page indentation under Debian's man page macros.

  From Steven Knight:

    - Clarify the man page description of the SConscript(src_dir) argument.

    - User's Guide updates:

       -  Document the BUILD_TARGETS, COMMAND_LINE_TARGETS and
          DEFAULT_TARGETS variables.

       -  Document the AddOption(), GetOption() and SetOption() functions.

       -  Document the Requires() function; convert to the Variables
          object, its UnknownOptions() method, and its associated
          BoolVariable(), EnumVariable(), ListVariable(), PackageVariable()
          and PathVariable() functions.

       -  Document the Progress() function.

       -  Reorganize the chapter and sections describing the different
          types of environments and how they interact.  Document the
          SetDefault() method.  Document the PrependENVPath() and
          AppendENVPath() functions.

       -  Reorganize the command-line arguments chapter.  Document the
          ARGLIST variable.

       -  Collect some miscellaneous sections into a chapter about
          configuring build output.

    - Man page updates:

       -  Document suggested use of the Visual C/C++ /FC option to fix
          the ability to double-click on file names in compilation error
          messages.

       -  Document the need to use Clean() for any SideEffect() files that
          must be explicitly removed when their targets are removed.

       -  Explicitly document use of Node lists as input to Dependency().

  From Greg Noel:

    - Document MergeFlags(), ParseConfig(), ParseFlags() and SideEffect()
      in the User's Guide.

  From Gary Oberbrunner:

    - Document use of the GetBuildFailures() function in the User's Guide.

  From Adam Simpkins:

    - Add man page text clarifying the behavior of AddPreAction() and
      AddPostAction() when called with multiple targets.

  From Alexey Zezukin:

    - Fix incorrectly swapped man page descriptions of the --warn= options
      for duplicate-environment and missing-sconscript.



RELEASE 0.98.5 - Sat, 07 Jun 2008 08:20:35 -0700

  From Benoit Belley:

  - Fix the Intel C++ compiler ABI specification for EMT64 processors.

  From David Cournapeau:

  - Issue a (suppressable) warning, not an error, when trying to link
    C++ and Fortran object files into the same executable.

  From Steven Knight:

  - Update the scons.bat file so that it returns the real exit status
    from SCons, even though it uses setlocal + endlocal.

  - Fix the --interactive post-build messages so it doesn't get stuck
    mistakenly reporting failures after any individual build fails.

  - Fix calling File() as a File object method in some circumstances.

  - Fix setup.py installation on Mac OS X so SCons gets installed
    under /usr/lcoal by default, not in the Mac OS X Python framework.



RELEASE 0.98.4 - Sat, 17 May 2008 22:14:46 -0700

  From Benoit Belley:

  - Fix calculation of signatures for Python function actions with
    closures in Python versions before 2.5.

  From David Cournapeau:

  - Fix the initialization of $SHF77FLAGS so it includes $F77FLAGS.

  From Jonas Olsson:

  - Fix a syntax error in the Intel C compiler support on Windows.

  From Steven Knight:

  - Change how we represent Python Value Nodes when printing and when
    stored in .sconsign files (to avoid blowing out memory by storing
    huge strings in .sconsign files after multiple runs using Configure
    contexts cause the Value strings to be re-escaped each time).

  - Fix a regression in not executing configuration checks after failure
    of any configuration check that used the same compiler or other tool.

  - Handle multiple destinations in Visual Studio 8 settings for the
    analogues to the INCLUDE, LIBRARY and PATH variables.

  From Greg Noel:

  - Update man page text for VariantDir().



RELEASE 0.98.3 - Tue, 29 Apr 2008 22:40:12 -0700

  From Greg Noel:

  - Fix use of $CXXFLAGS when building C++ shared object files.

  From Steven Knight:

  - Fix a regression when a Builder's source_scanner doesn't select
    a more specific scanner for the suffix of a specified source file.

  - Fix the Options object backwards compatibility so people can still
    "import SCons.Options.{Bool,Enum,List,Package,Path}Option" submodules.

  - Fix searching for implicit dependencies when an Entry Node shows up
    in the search path list.

  From Stefano:

  - Fix expansion of $FORTRANMODDIR in the default Fortran command line(s)
    when it's set to something like ${TARGET.dir}.



RELEASE 0.98.2 - Sun, 20 Apr 2008 23:38:56 -0700

  From Steven Knight:

  - Fix a bug in Fortran suffix computation that would cause SCons to
    run out of memory on Windows systems.

  - Fix being able to specify --interactive mode command lines with
    \ (backslash) path name separators on Windows.

  From Gary Oberbrunner:

  - Document Glob() in the User's Guide.



RELEASE 0.98.1 - Fri, 18 Apr 2008 19:11:58 -0700

  From Benoit Belley:

  - Speed up the SCons.Util.to_string*() functions.

  - Optimize various Node intialization and calculations.

  - Optimize Executor scanning code.

  - Optimize Taskmaster execution, including dependency-cycle checking.

  - Fix the --debug=stree option so it prints its tree once, not twice.

  From Johan Boul�:

  - Fix the ability to use LoadableModule() under MinGW.

  From David Cournapeau:

  - Various missing Fortran-related construction variables have been added.

  - SCons now uses the program specified in the $FORTRAN construction
    variable to link Fortran object files.

  - Fortran compilers on Linux (Intel, g77 and gfortran) now add the -fPIC
    option by default when compilling shared objects.

  - New 'sunf77', 'sunf90' and 'sunf95' Tool modules have been added to
    support Sun Fortran compilers.  On Solaris, the Sun Fortran compilers
    are used in preference to other compilers by default.

  - Fortran support now uses gfortran in preference to g77.

  - Fortran file suffixes are now configurable through the
    $F77FILESUFFIXES, $F90FILESUFFIXES, $F95FILESUFFIXES and
    $FORTRANFILESUFFIXES variables.

  From Steven Knight:

  - Make the -d, -e, -w and --no-print-directory options "Ignored for
    compatibility."  (We're not going to implement them.)

  - Fix a serious inefficiency in how SCons checks for whether any source
    files are missing when a Builder call creates many targets from many
    input source files.

  - In Java projects, make the target .class files depend only on the
    specific source .java files where the individual classes are defined.

  - Don't store duplicate source file entries  in the .sconsign file so
    we don't endlessly rebuild the target(s) for no reason.

  - Add a Variables object as the first step towards deprecating the
    Options object name.  Similarly, add BoolVariable(), EnumVariable(),
    ListVariable(), PackageVariable() and PathVariable() functions
    as first steps towards replacing BoolOption(), EnumOption(),
    ListOption(), PackageOption() and PathOption().

  - Change the options= keyword argument to the Environment() function
    to variables=, to avoid confusion with SCons command-line options.
    Continue supporting the options= keyword for backwards compatibility.

  - When $SWIGFLAGS contains the -python flag, expect the generated .py
    file to be in the same (sub)directory as the target.

  - When compiling C++ files, allow $CCFLAGS settings to show up on the
    command line even when $CXXFLAGS has been redefined.

  - Fix --interactive with -u/-U/-D when a VariantDir() is used.

  From Anatoly Techtonik:

  - Have the scons.bat file add the script execution directory to its
    local %PATH% on Windows, so the Python executable can be found.

  From Mike Wake:

  - Fix passing variable names as a list to the Return() function.

  From Matthew Wesley:

  - Add support for the GDC 'D' language compiler.



RELEASE 0.98 - Sun, 30 Mar 2008 23:33:05 -0700

  From Benoit Belley:

  - Fix the --keep-going flag so it builds all possible targets even when
    a later top-level target depends on a child that failed its build.

  - Fix being able to use $PDB and $WINDWOWS_INSERT_MANIFEST together.

  - Don't crash if un-installing the Intel C compiler leaves left-over,
    dangling entries in the Windows registry.

  - Improve support for non-standard library prefixes and suffixes by
    stripping all prefixes/suffixes from file name string as appropriate.

  - Reduce the default stack size for -j worker threads to 256 Kbytes.
    Provide user control over this value by adding --stack-size and
    --warn=stack-size options, and a SetOption('stack_size') function.

  - Fix a crash on Linux systems when trying to use the Intel C compiler
    and no /opt/intel_cc_* directories are found.

  - Improve using Python functions as actions by incorporating into
    a FunctionAction's signature:
      - literal values referenced by the byte code.
      - values of default arguments
      - code of nested functions
      - values of variables captured by closures
      - names of referenced global variables and functions

  - Fix the closing message when --clean and --keep-going are both
    used and no errors occur.

  - Add support for the Intel C compiler on Mac OS X.

  - Speed up reading SConscript files by about 20% (for some
    configurations) by:  1) optimizing the SCons.Util.is_*() and
    SCons.Util.flatten() functions; 2) avoiding unnecessary os.stat()
    calls by using a File's .suffix attribute directly instead of
    stringifying it.

  From Jérôme Berger:

  - Have the D language scanner search for .di files as well as .d files.

  - Add a find_include_names() method to the Scanner.Classic class to
    abstract out how included names can be generated by subclasses.

  - Allow the D language scanner to detect multiple modules imported by
    a single statement.

  From Konstantin Bozhikov:

  - Support expansion of construction variables that contain or refer
    to lists of other variables or Nodes within expansions like $CPPPATH.

  - Change variable substitution (the env.subst() method) so that an
    input sequence (list or tuple) is preserved as a list in the output.

  From David Cournapeau:

  - Add a CheckDeclaration() call to configure contexts.

  - Improve the CheckTypeSize() code.

  - Add a Define() call to configure contexts, to add arbitrary #define
    lines to a generated configure header file.

  - Add a "gfortran" Tool module for the GNU F95/F2003 compiler.

  - Avoid use of -rpath with the Mac OS X linker.

  - Add comment lines to the generated config.h file to describe what
    the various #define/#undef lines are doing.

  From Steven Knight:

  - Support the ability to subclass the new-style "str" class as input
    to Builders.

  - Improve the performance of our type-checking by using isinstance()
    with new-style classes.

  - Fix #include (and other $*PATH variables searches) of files with
    absolute path names.  Don't die if they don't exist (due to being
    #ifdef'ed out or the like).

  - Fix --interactive mode when Default(None) is used.

  - Fix --debug=memoizer to work around a bug in base Python 2.2 metaclass
    initialization (by just not allowing Memoization in Python versions
    that have the bug).

  - Have the "scons-time time" subcommand handle empty log files, and
    log files that contain no results specified by the --which option.

  - Fix the max Y of vertical bars drawn by "scons-time --fmt=gnuplot".

  - On Mac OS X, account for the fact that the header file generated
    from a C++ file will be named (e.g.) file.cpp.h, not file.hpp.

  - Fix floating-point numbers confusing the Java parser about
    generated .class file names in some configurations.

  - Document (nearly) all the values you can now fetch with GetOption().

  - Fix use of file names containing strings of multiple spaces when
    using ActionFactory instances like the Copy() or Move() function.

  - Fix a 0.97 regression when using a variable expansion (like
    $OBJSUFFIX) in a source file name to a builder with attached source
    builders that match suffix (like Program()+Object()).

  - Have the Java parser recognize generics (surrounded by angle brackets)
    so they don't interfere with identifying anonymous inner classes.

  - Avoid an infinite loop when trying to use saved copies of the
    env.Install() or env.InstallAs() after replacing the method
    attributes.

  - Improve the performance of setting construction variables.

  - When cloning a construction environment, avoid over-writing an
    attribute for an added method if the user explicitly replaced it.

  - Add a warning about deprecated support for Python 1.5, 2.0 and 2.1.

  - Fix being able to SetOption('warn', ...) in SConscript files.

  - Add a warning about env.Copy() being deprecated.

  - Add warnings about the --debug={dtree,stree,tree} options
    being deprecated.

  - Add VariantDir() as the first step towards deprecating BuildDir().
    Add the keyword argument "variant_dir" as the replacement for
    "build_dir".

  - Add warnings about the {Target,Source}Signatures() methods and
    functions being deprecated.

  From Rob Managan:

  - Enhance TeX and LaTeX support to work with BuildDir(duplicate=0).

  - Re-run LaTeX when it issues a package warning that it must be re-run.

  From Leanid Nazdrynau:

  - Have the Copy() action factory preserve file modes and times
    when copying individual files.

  From Jan Nijtmans:

  - If $JARCHDIR isn't set explicitly, use the .java_classdir attribute
    that was set when the Java() Builder built the .class files.

  From Greg Noel:

  - Document the Dir(), File() and Entry() methods of Dir and File Nodes.

  - Add the parse_flags option when creating Environments

  From Gary Oberbrunner:

  - Make File(), Dir() and Entry() return a list of Nodes when passed
    a list of names, instead of trying to make a string from the name
    list and making a Node from that string.

  - Fix the ability to build an Alias in --interactive mode.

  - Fix the ability to hash the contents of actions for nested Python
    functions on Python versions where the inability to pickle them
    returns a TypeError (instead of the documented PicklingError).

  From Jonas Olsson:

  - Fix use of the Intel C compiler when the top compiler directory,
    but not the compiler version, is specified.

  - Handle Intel C compiler network license files (port@system).

  From Jim Randall:

  - Fix how Python Value Nodes are printed in --debug=explain output.

  From Adam Simpkins:

  - Add a --interactive option that starts a session for building (or
    cleaning) targets without re-reading the SConscript files every time.

  - Fix use of readline command-line editing in --interactive mode.

  - Have the --interactive mode "build" command with no arguments
    build the specified Default() targets.

  - Fix the Chmod(), Delete(), Mkdir() and Touch() Action factories to
    take a list (of Nodes or strings) as arguments.

  From Vaclav Smilauer:

  - Fix saving and restoring an Options value of 'all' on Python
    versions where all() is a builtin function.

  From Daniel Svensson:

  - Code correction in SCons.Util.is_List().

  From Ben Webb:

  - Support the SWIG %module statement with following modifiers in
    parenthese (e.g., '%module(directors="1")').



RELEASE 0.97.0d20071212 - Wed, 12 Dec 2007 09:29:32 -0600

  From Benoit Belley:

  - Fix occasional spurious rebuilds and inefficiency when using
    --implicit-cache and Builders that produce multiple targets.

  - Allow SCons to not have to know about the builders of generated
    files when BuildDir(duplicate=0) is used, potentially allowing some
    SConscript files to be ignored for smaller builds.

  From David Cournapeau:

  - Add a CheckTypeSize() call to configure contexts.

  From Ken Deeter:

  - Make the "contents" of Alias Nodes a concatenation of the children's
    content signatures (MD5 checksums), not a concatenation of the
    children's contents, to avoid using large amounts of memory during
    signature calculation.

  From Malte Helmert:

  - Fix a lot of typos in the man page and User's Guide.

  From Geoffrey Irving:

  - Speed up conversion of paths in .sconsign files to File or Dir Nodes.

  From Steven Knight:

  - Add an Options.UnknownOptions() method that returns any settings
    (from the command line, or whatever dictionary was passed in)
    that aren't known to the Options object.

  - Add a Glob() function.

  - When removing targets with the -c option, use the absolute path (to
    avoid problems interpreting BuildDir() when the top-level directory
    is the source directory).

  - Fix problems with Install() and InstallAs() when called through a
    clone (of a clone, ...) of a cloned construction environment.

  - When executing a file containing Options() settings, add the file's
    directory to sys.path (so modules can be imported from there) and
    explicity set __name__ to the name of the file so the statement's
    in the file can deduce the location if they need to.

  - Fix an O(n^2) performance problem when adding sources to a target
    through calls to a multi Builder (including Aliases).

  - Redefine the $WINDOWSPROGMANIFESTSUFFIX and
    $WINDOWSSHLIBMANIFESTSUFFIX variables so they pick up changes to
    the underlying $SHLIBSUFFIX and $PROGSUFFIX variables.

  - Add a GetBuildFailures() function that can be called from functions
    registered with the Python atexit module to print summary information
    about any failures encountered while building.

  - Return a NodeList object, not a Python list, when a single_source
    Builder like Object() is called with more than one file.

  - When searching for implicit dependency files in the directories
    in a $*PATH list, don't create Dir Nodes for directories that
    don't actually exist on-disk.

  - Add a Requires() function to allow the specification of order-only
    prerequisites, which will be updated before specified "downstream"
    targets but which don't actually cause the target to be rebuilt.

  - Restore the FS.{Dir,File,Entry}.rel_path() method.

  - Make the default behavior of {Source,Target}Signatures('timestamp')
    be equivalent to 'timestamp-match', not 'timestamp-newer'.

  - Fix use of CacheDir with Decider('timestamp-newer') by updating
    the modification time when copying files from the cache.

  - Fix random issues with parallel (-j) builds on Windows when Python
    holds open file handles (especially for SCons temporary files,
    or targets built by Python function actions) across process creation.

  From Maxim Kartashev:

  - Fix test scripts when run on Solaris.

  From Gary Oberbrunner:

  - Fix Glob() when a pattern is in an explicitly-named subdirectory.

  From Philipp Scholl:

  - Fix setting up targets if multiple Package builders are specified
    at once.



RELEASE 0.97.0d20070918 - Tue, 18 Sep 2007 10:51:27 -0500

  From Steven Knight:

  - Fix the wix Tool module to handle null entries in $PATH variables.

  - Move the documentation of Install() and InstallAs() from the list
    of functions to the list of Builders (now that they're implemented
    as such).

  - Allow env.CacheDir() to be set per construction environment.  The
    global CacheDir() function now sets an overridable global default.

  - Add an env.Decider() method and a Node.Decider() method that allow
    flexible specification of an arbitrary function to decide if a given
    dependency has changed since the last time a target was built.

  - Don't execute Configure actions (while reading SConscript files)
    when cleaning (-c) or getting help (-h or -H).

  - Add to each target an implicit dependency on the external command(s)
    used to build the target, as found by searching env['ENV']['PATH']
    for the first argument on each executed command line.

  - Add support for a $IMPLICIT_COMMAND_DEPENDENCIES construction
    variabe that can be used to disable the automatic implicit
    dependency on executed commands.

  - Add an "ensure_suffix" keyword to Builder() definitions that, when
    true, will add the configured suffix to the targets even if it looks
    like they already have a different suffix.

  - Add a Progress() function that allows for calling a function or string
    (or list of strings) to display progress while walking the DAG.

  - Allow ParseConfig(), MergeFlags() and ParseFlags() to handle output
    from a *config command with quoted path names that contain spaces.

  - Make the Return() function stop processing the SConscript file and
    return immediately.  Add a "stop=" keyword argument that can be set
    to False to preserve the old behavior.

  - Fix use of exitstatfunc on an Action.

  - Introduce all man page function examples with "Example:" or "Examples:".

  - When a file gets added to a directory, make sure the directory gets
    re-scanned for the new implicit dependency.

  - Fix handling a file that's specified multiple times in a target
    list so that it doesn't cause dependent Nodes to "disappear" from
    the dependency graph walk.

  From Carsten Koch:

  - Avoid race conditions with same-named files and directory creation
    when pushing copies of files to CacheDir().

  From Tzvetan Mikov:

  - Handle $ in Java class names.

  From Gary Oberbrunner:

  - Add support for the Intel C compiler on Windows64.

  - On SGI IRIX, have $SHCXX use $CXX by default (like other platforms).

  From Sohail Somani:

  - When Cloning a construction environment, set any variables before
    applying tools (so the tool module can access the configured settings)
    and re-set them after (so they end up matching what the user set).

  From Matthias Troffaes:

  - Make sure extra auxiliary files generated by some LaTeX packages
    and not ending in .aux also get deleted by scons -c.

  From Greg Ward:

  - Add a $JAVABOOTCLASSPATH variable for directories to be passed to the
    javac -bootclasspath option.

  From Christoph Wiedemann:

  - Add implicit dependencies on the commands used to build a target.




RELEASE 0.97.0d20070809 - Fri, 10 Aug 2007 10:51:27 -0500

  From Lars Albertsson:

  - Don't error if a #include line happens to match a directory
    somewhere on a path (like $CPPPATH, $FORTRANPATH, etc.).

  From Mark Bertoglio:

  - Fix listing multiple projects in Visual Studio 7.[01] solution files,
    including generating individual project GUIDs instead of re-using
    the solution GUID.

  From Jean Brouwers:

  - Add /opt/SUNWspro/bin to the default execution PATH on Solaris.

  From Allan Erskine:

  - Only expect the Microsoft IDL compiler to emit *_p.c and *_data.c
    files if the /proxy and /dlldata switches are used (respectively).

  From Steven Knight:

  - Have --debug=explain report if a target is being rebuilt because
    AlwaysBuild() is specified (instead of "unknown reasons").

  - Support {Get,Set}Option('help') to make it easier for SConscript
    files to tell if a help option (-h, --help, etc.) has been specified.

  - Support {Get,Set}Option('random') so random-dependency interaction
    with CacheDir() is controllable from SConscript files.

  - Add a new AddOption() function to support user-defined command-
    line flags (like --prefix=, --force, etc.).

  - Replace modified Optik version with new optparse compatibility module
    for command line processing in Scripts/SConsOptions.py

  - Push and retrieve built symlinks to/from a CacheDir() as actual
    symlinks, not by copying the file contents.

  - Fix how the Action module handles stringifying the shared library
    generator in the Tool/mingw.py module.

  - When generating a config.h file, print "#define HAVE_{FEATURE} 1"
    instad of just "#define HAVE_{FEATURE}", for more compatibility
    with Autoconf-style projects.

  - Fix expansion of $TARGET, $TARGETS, $SOURCE and $SOURCES keywords in
    Visual C/C++ PDB file names.

  - Fix locating Visual C/C++ PDB files in build directories.

  - Support an env.AddMethod() method and an AddMethod() global function
    for adding a new method, respectively, to a construction environment
    or an arbitrary object (such as a class).

  - Fix the --debug=time option when the -j option is specified and all
    files are up to date.

  - Add a $SWIGOUTDIR variable to allow setting the swig -outdir option,
    and use it to identify files created by the swig -java option.

  - Add a $SWIGPATH variable that specifies the path to be searched
    for included SWIG files, Also add related $SWIGINCPREFIX and
    $SWIGINCSUFFIX variables that specify the prefix and suffix to
    be be added to each $SWIGPATH directory when expanded on the SWIG
    command line.

  - More efficient copying of construction environments (mostly borrowed
    from copy.deepcopy() in the standard Python library).

  - When printing --tree=prune output, don't print [brackets] around
    source files, only do so for built targets with children.

  - Fix interpretation of Builder source arguments when the Builder has
    a src_suffix *and* a source_builder and the argument has no suffix.

  - Fix use of expansions like ${TARGET.dir} or ${SOURCE.dir} in the
    following construction variables:  $FORTRANMODDIR, $JARCHDIR,
    $JARFLAGS, $LEXFLAGS, $SWIGFLAGS, $SWIGOUTDIR and $YACCFLAGS.

  - Fix dependencies on Java files generated by SWIG so they can be
    detected and built in one pass.

  - Fix SWIG when used with a BuildDir().

  From Leanid Nazdrynau:

  - When applying Tool modules after a construction environment has
    already been created, don't overwrite existing $CFILESUFFIX and
    $CXXFILESUFFIX value.

  - Support passing the Java() builder a list of explicit .java files
    (not only a list of directories to be scanned for .java files).

  - Support passing .java files to the Jar() and JavaH() builders, which
    then use the builder underlying the Java() builder to turn them into
    .class files.  (That is, the Jar()-Java() chain of builders become
    multi-step, like the Program()-Object()-CFile() builders.)

  - Support passing SWIG .i files to the Java builders (Java(),
    Jar(), JavaH()), to cause intermediate .java files to be created
    automatically.

  - Add $JAVACLASSPATH and $JAVASOURCEPATH variables, that get added to
    the javac "-classpath" and "-sourcepath" options.  (Note that SCons
    does *not* currently search these paths for implicit dependencies.)

  - Commonize initialization of Java-related builders.

  From Jan Nijtmans:

  - Find Java anonymous classes when the next token after the name is
    an open parenthesis.

  From Gary Oberbrunner:

  - Fix a code example in the man page.

  From Tilo Prutz:

  - Add support for the file names that Java 1.5 (and 1.6) generates for
    nested anonymous inner classes, which are different from Java 1.4.

  From Adam Simpkins:

  - Allow worker threads to terminate gracefully when all jobs are
    finished.

  From Sohail Somani:

  - Add LaTeX scanner support for finding dependencies specified with
    the \usepackage{} directive.



RELEASE 0.97 - Thu, 17 May 2007 08:59:41 -0500

  From Steven Knight:

  - Fix a bug that would make parallel builds stop in their tracks if
    Nodes that depended on lists that contained some Nodes built together
    caused the reference count to drop below 0 if the Nodes were visited
    and commands finished in the wrong order.

  - Make sure the DirEntryScanner doesn't choke if it's handed something
    that's not a directory (Node.FS.Dir) Node.



RELEASE 0.96.96 - Thu, 12 Apr 2007 12:36:25 -0500

  NOTE:  This is (Yet) a(nother) pre-release of 0.97 for testing purposes.

  From Joe Bloggs:

  - Man page fix:  remove cut-and-paste sentence in NoCache() description.

  From Dmitry Grigorenko and Gary Oberbrunner:

  - Use the Intel C++ compiler, not $CC, to link C++ source.

  From Helmut Grohne:

  - Fix the man page example of propagating a user's external environment.

  From Steven Knight:

  - Back out (most of) the Windows registry installer patch, which
    seems to not work on some versions of Windows.

  - Don't treat Java ".class" attributes as defining an inner class.

  - Fix detecting an erroneous Java anonymous class when the first
    non-skipped token after a "new" keyword is a closing brace.

  - Fix a regression when a CPPDEFINES list contains a tuple, the second
    item of which (the option value) is a construction variable expansion
    (e.g. $VALUE) and the value of the variable isn't a string.

  - Improve the error message if an IOError (like trying to read a
    directory as a file) occurs while deciding if a node is up-to-date.

  - Fix "maximum recursion" / "unhashable type" errors in $CPPPATH
    PathList expansion if a subsidiary expansion yields a stringable,
    non-Node object.

  - Generate API documentation from the docstrings (using epydoc).

  - Fix use of --debug=presub with Actions for out-of-the-box Builders.

  - Fix handling nested lists within $CPPPATH, $LIBPATH, etc.

  - Fix a "builders_used" AttributeError that real-world Qt initialization
    triggered in the refactored suffix handling for Builders.

  - Make the reported --debug=time timings meaningful when used with -j.
    Better documentation of what the times mean.

  - User Guide updates: --random, AlwaysBuild(), --tree=,
    --debug=findlibs, --debug=presub, --debug=stacktrace,
    --taskmastertrace.

  - Document (in both man page and User's Guide) that --implicit-cache
    ignores changes in $CPPPATH, $LIBPATH, etc.

  From Jean-Baptiste Lab:

  - Remove hard-coded dependency on Python 2.2 from Debian packaging files.

  From Jeff Mahovsky:

  - Handle spaces in the build target name in Visual Studio project files.

  From Rob Managan:

  - Re-run LaTeX after BibTeX has been re-run in response to a changed
    .bib file.

  From Joel B. Mohler:

  - Make additional TeX auxiliary files (.toc, .idx and .bbl files)
    Precious so their removal doesn't affect whether the necessary
    sections are included in output PDF or PostScript files.

  From Gary Oberbrunner:

  - Fix the ability to import modules in the site_scons directory from
    a subdirectory.

  From Adam Simpkins:

  - Make sure parallel (-j) builds all targets even if they show up
    multiple times in the child list (as a source and a dependency).

  From Matthias Troffaes:

  - Don't re-run TeX if the triggering strings (\makeindex, \bibliography
    \tableofcontents) are commented out.

  From Richard Viney:

  - Fix use of custom include and lib paths with Visual Studio 8.

  - Select the default .NET Framework SDK Dir based on the version of
    Visual Studio being used.



RELEASE 0.96.95 - Mon, 12 Feb 2007 20:25:16 -0600

  From Anatoly Techtonik:

  - Add the scons.org URL and a package description to the setup.py
    arguments.

  - Have the Windows installer add a registry entry for scons.bat in the
    "App Paths" key, so scons.bat can be executed without adding the
    directory to the %PATH%.  (Python itself works this way.)

  From Anonymous:

  - Fix looking for default paths in Visual Studio 8.0 (and later).

  - Add -lm to the list of default D libraries for linking.

  From Matt Doar:

  - Provide a more complete write-your-own-Scanner example in the man page.

  From Ralf W. Grosse-Kunstleve:

  - Contributed upstream Python change to our copied subprocess.py module
    for more efficient standard input processing.

  From Steven Knight:

  - Fix the Node.FS.Base.rel_path() method when the two nodes are on
    different drive letters.  (This caused an infinite loop when
    trying to write .sconsign files.)

  - Fully support Scanners that use a dictionary to map file suffixes
    to other scanners.

  - Support delayed evaluation of the $SPAWN variable to allow selection
    of a function via ${} string expansions.

  - Add --srcdir as a synonym for -Y/--repository.

  - Document limitations of #include "file.h" with Repository().

  - Fix use of a toolpath under the source directory of a BuildDir().

  - Fix env.Install() with a file name portion that begins with '#'.

  - Fix ParseConfig()'s handling of multiple options in a string that's
    replaced a *FLAGS construction variable.

  - Have the C++ tools initialize common C compilation variables ($CCFLAGS,
    $SHCCFLAGS and $_CCCOMCOM) even if the 'cc' Tool isn't loaded.

  From Leanid Nazdrynau:

  - Fix detection of Java anonymous classes if a newline precedes the
    opening brace.

  From Gary Oberbrunner:

  - Document use of ${} to execute arbitrary Python code.

  - Add support for:
    1) automatically adding a site_scons subdirectory (in the top-level
       SConstruct directory) to sys.path (PYTHONPATH);
    2) automatically importing site_scons/site_init.py;
    3) automatically adding site_scons/site_tools to the toolpath.

  From John Pye:

  - Change ParseConfig() to preserve white space in arguments passed in
    as a list.

  From a smith:

  - Fix adding explicitly-named Java inner class files (and any
    other file names that may contain a '$') to Jar files.

  From David Vitek:

  - Add a NoCache() function to mark targets as unsuitable for propagating
    to (or retrieving from) a CacheDir().

  From Ben Webb:

  - If the swig -noproxy option is used, it won't generate a .py file,
    so don't emit it as a target that we expect to be built.



RELEASE 0.96.94 - Sun, 07 Jan 2007 18:36:20 -0600

  NOTE:  This is a pre-release of 0.97 for testing purposes.

  From Anonymous:

  - Allow arbitrary white space after a SWIG %module declaration.

  From Paul:

  - When compiling resources under MinGW, make sure there's a space
    between the --include-dir option and its argument.

  From Jay Kint:

  - Alleviate long command line issues on Windows by executing command
    lines directly via os.spawnv() if the command line doesn't need
    shell interpretation (has no pipes, redirection, etc.).

  From Walter Franzini:

  - Exclude additional Debian packaging files from the copyright check.

  From Fawad Halim:

  - Handle the conflict between the impending Python 2.6 'as' keyword
    and our Tool/as.py module name.

  From Steven Knight:

  - Speed up the Node.FS.Dir.rel_path() method used to generate path names
    that get put into the .sconsign* file(s).

  - Optimize Node.FS.Base.get_suffix() by computing the suffix once, up
    front, when we set the Node's name.  (Duh...)

  - Reduce the Memoizer's responsibilities to simply counting hits and
    misses when the --debug=memoizer option is used, not to actually
    handling the key calculation and memoization itself.  This speeds
    up some configurations significantly, and should cause no functional
    differences.

  - Add a new scons-time script with subcommands for generating
    consistent timing output from SCons configurations, extracting
    various information from those timings, and displaying them in
    different formats.

  - Reduce some unnecessary stat() calls from on-disk entry type checks.

  - Fix SideEffect() when used with -j, which was badly broken in 0.96.93.

  - Propagate TypeError exceptions when evaluating construction variable
    expansions up the stack, so users can see what's going on.

  - When disambiguating a Node.FS.Entry into a Dir or File, don't look
    in the on-disk source directory until we've confirmed there's no
    on-disk entry locally and there *is* one in the srcdir.  This avoids
    creating a phantom Node that can interfere with dependencies on
    directory contents.

  - Add an AllowSubstExceptions() function that gives the SConscript
    files control over what exceptions cause a string to expand to ''
    vs. terminating processing with an error.

  - Allow the f90.py and f95.py Tool modules to compile earlier source
    source files of earlier Fortran version.

  - Fix storing signatures of files retrieved from CacheDir() so they're
    correctly identified as up-to-date next invocation.

  - Make sure lists of computed source suffixes cached by Builder objects
    don't persist across changes to the list of source Builders (so the
    addition of suffixes like .ui by the qt.py Tool module take effect).

  - Enhance the bootstrap.py script to allow it to be used to execute
    SCons more easily from a checked-out source tree.

  From Ben Leslie:

  - Fix post-Memoizer value caching misspellings in Node.FS._doLookup().

  From Rob Managan, Dmitry Mikhin and Joel B. Mohler:

  - Handle TeX/LaTeX files in subdirectories by changing directory
    before invoking TeX/LaTeX.

  - Scan LaTeX files for \bibliography lines.

  - Support multiple file names in a "\bibliography{file1,file2}" string.

  - Handle TeX warnings about undefined citations.

  - Support re-running LaTeX if necessary due to a Table of Contents.

  From Dmitry Mikhin:

  - Return LaTeX if "Rerun to get citations correct" shows up on the next
    line after the "Warning:" string.

  From Gary Oberbrunner:

  - Add #include lines to fix portability issues in two tests.

  - Eliminate some unnecessary os.path.normpath() calls.

  - Add a $CFLAGS variable for C-specific options, leaving $CCFLAGS
    for options common to C and C++.

  From Tom Parker:

  - Have the error message print the missing file that Qt can't find.

  From John Pye:

  - Fix env.MergeFlags() appending to construction variable value of None.

  From Steve Robbins:

  - Fix the "sconsign" script when the .sconsign.dblite file is explicitly
    specified on the command line (and not intuited from the old way of
    calling it with just ".sconsign").

  From Jose Pablo Ezequiel "Pupeno" Fernandez Silva:

  - Give the 'lex' tool knowledge of the additional target files produced
    by the flex "--header-file=" and "--tables-file=" options.

  - Give the 'yacc' tool knowledge of the additional target files produced
    by the bison "-g", "--defines=" and "--graph=" options.

  - Generate intermediate files with Objective C file suffixes (.m) when
    the lex and yacc source files have appropriate suffixes (.lm and .ym).

  From Sohail Somain:

  - Have the mslink.py Tool only look for a 'link' executable on Windows
    systems.

  From Vaclav Smilauer:

  - Add support for a "srcdir" keyword argument when calling a Builder,
    which will add a srcdir prefix to all non-relative string sources.

  From Jonathan Ultis:

  - Allow Options converters to take the construction environment as
    an optional argument.



RELEASE 0.96.93 - Mon, 06 Nov 2006 00:44:11 -0600

  NOTE:  This is a pre-release of 0.97 for testing purposes.

  From Anonymous:

  - Allow Python Value Nodes to be Builder targets.

  From Matthias:

  - Only filter Visual Studio common filename prefixes on complete
    directory names.

  From Chad Austin:

  - Fix the build of the SCons documentation on systems that don't
    have "python" in the $PATH.

  From Ken Boortz:

  - Enhance ParseConfig() to recognize options that begin with '+'.

  From John Calcote, Elliot Murphy:

  - Document ways to override the CCPDBFLAGS variable to use the
    Microsoft linker's /Zi option instead of the default /Z7.

  From Christopher Drexler:

  - Make SCons aware bibtex must be called if any \include files
    cause creation of a bibliography.

  - Make SCons aware that "\bilbiography" in TeX source files means
    that related .bbl and .blg bibliography files will be created.
    (NOTE:  This still needs to search for the string in \include files.)

  From David Gruener:

  - Fix inconsistent handling of Action strfunction arguments.

  - Preserve white space in display Action strfunction strings.

  From James Y. Knight and Gerard Patel:

  - Support creation of shared object files from assembly language.

  From Steven Knight:

  - Speed up the Taskmaster significantly by avoiding unnecessary
    re-scans of Nodes to find out if there's work to be done, having it
    track the currently-executed top-level target directly and not
    through its presence on the target list, and eliminating some other
    minor list(s), method(s) and manipulation.

  - Fix the expansion of $TARGET and $SOURCE in the expansion of
    $INSTALLSTR displayed for non-environment calls to InstallAs().

  - Fix the ability to have an Alias() call refer to a directory
    name that's not identified as a directory until later.

  - Enhance runtest.py with an option to use QMTest as the harness.
    This will become the default behavior as we add more functionality
    to the QMTest side.

  - Let linking on mingw use the default function that chooses $CC (gcc)
    or $CXX (g++) depending on whether there are any C++ source files.

  - Work around a bug in early versions of the Python 2.4 profile module
    that caused the --profile= option to fail.

  - Only call Options validators and converters once when initializing a
    construction environment.

  - Fix the ability of env.Append() and env.Prepend(), in all known Python
    versions, to handle different input value types when the construction
    variable being updated is a dictionary.

  - Add a --cache-debug option for information about what files it's
    looking for in a CacheDir().

  - Document the difference in construction variable expansion between
    {Action,Builder}() and env.{Action,Builder}().

  - Change the name of env.Copy() to env.Clone(), keeping the old name
    around for backwards compatibility (with the intention of eventually
    phasing it out to avoid confusion with the Copy() Action factory).

  From Arve Knudsen:

  - Support cleaning and scanning SWIG-generated files.

  From Carsten Koch:

  - Allow selection of Visual Studio version by setting $MSVS_VERSION
    after construction environment initialization.

  From Jean-Baptiste Lab:

  - Try using zipimport if we can't import Tool or Platform modules
    using the normal "imp" module.  This allows SCons to be packaged
    using py2exe's all-in-one-zip-file approach.

  From Ben Liblit:

  - Do not re-scan files if the scanner returns no implicit dependencies.

  From Sanjoy Mahajan:

  - Change use of $SOURCES to $SOURCE in all TeX-related Tool modules.

  From Joel B. Mohler:

  - Make SCons aware that "\makeindex" in TeX source files means that
    related .ilg, .ind and .idx index files will be created.
    (NOTE:  This still needs to search for the string in \include files.)

  - Prevent scanning the TeX .aux file for additional files from
    trying to remove it twice when the -c option is used.

  From Leanid Nazdrynau:

  - Give the MSVC RES (resource) Builder a src_builder list and a .rc
    src_suffix so other builders can generate .rc files.

  From Matthew A. Nicholson:

  - Enhance Install() and InstallAs() to handle directory trees as sources.

  From Jan Nijtmans:

  - Don't use the -fPIC flag when using gcc on Windows (e.g. MinGW).

  From Greg Noel:

  - Add an env.ParseFlags() method that provides separate logic for
    parsing GNU tool chain flags into a dictionary.

  - Add an env.MergeFlags() method to apply an arbitrary dictionary
    of flags to a construction environment's variables.

  From Gary Oberbrunner:

  - Fix parsing tripartite Intel C compiler version numbers on Linux.

  - Extend the ParseConfig() function to recognize -arch and
    -isysroot options.

  - Have the error message list the known suffixes when a Builder call
    can't build a source file with an unknown suffix.

  From Karol Pietrzak:

  - Avoid recursive calls to main() in the program snippet used by the
    SConf subsystem to test linking against libraries.  This changes the
    default behavior of CheckLib() and CheckLibWithHeader() to print
    "Checking for C library foo..." instead of "Checking for main()
    in C library foo...".

  From John Pye:

  - Throw an exception if a command called by ParseConfig() or
    ParseFlags() returns an error.

  From Stefan Seefeld:

  - Initial infrastructure for running SCons tests under QMTest.

  From Sohail Somani:

  - Fix tests that fail due to gcc warnings.

  From Dobes Vandermeer:

  - In stack traces, print the full paths of SConscript files.

  From Atul Varma:

  - Fix detection of Visual C++ Express Edition.

  From Dobes Vandermeer:

  - Let the src_dir option to the SConscript() function affect all the
    the source file paths, instead of treating all source files paths
    as relative to the SConscript directory itself.

  From Nicolas Vigier:

  - Fix finding Fortran modules in build directories.

  - Fix use of BuildDir() when the source file in the source directory
    is a symlink with a relative path.

  From Edward Wang:

  - Fix the Memoizer when the SCons Python modules are executed from
    .pyo files at different locations from where they were compiled.

  From Johan Zander:

  - Fix missing os.path.join() when constructing the $FRAMEWORKSDKDIR/bin.



RELEASE 0.96.92 - Mon, 10 Apr 2006 21:08:22 -0400

  NOTE:  This was a pre-release of 0.97 for testing purposes.

  From Anonymous:

  - Fix the intelc.py Tool module to not throw an exception if the
    only installed version is something other than ia32.

  - Set $CCVERSION when using gcc.

  From Matthias:

  - Support generating project and solution files for Microsoft
    Visual Studio version 8.

  - Support generating more than one project file for a Microsoft
    Visual Studio solution file.

  - Add support for a support "runfile" parameter to Microsoft
    Visual Studio project file creation.

  - Put the project GUID, not the solution GUID, in the right spot
    in the solution file.

  From Erling Andersen:

  - Fix interpretation of Node.FS objects wrapped in Proxy instances,
    allowing expansion of things like ${File(TARGET)} in command lines.

  From Stanislav Baranov:

  - Add a separate MSVSSolution() Builder, with support for the
    following new construction variables: $MSVSBUILDCOM, $MSVSCLEANCOM,
    $MSVSENCODING, $MSVSREBUILDCOM, $MSVSSCONS, $MSVSSCONSCOM,
    $MSVSSCONSFLAGS, $MSVSSCONSCRIPT and $MSVSSOLUTIONCOM.

  From Ralph W. Grosse-Kunstleve and Patrick Mezard:

  - Remove unneceesary (and incorrect) SCons.Util strings on some function
    calls in SCons.Util.

  From Bob Halley:

  - Fix C/C++ compiler selection on AIX to not always use the external $CC
    environment variable.

  From August Hörandl:

  - Add a scanner for \include and \import files, with support for
    searching a directory list in $TEXINPUTS (imported from the external
    environment).

  - Support $MAKEINDEX, $MAKEINDEXCOM, $MAKEINDEXCOMSTR and
    $MAKEINDEXFLAGS for generating indices from .idx files.

  From Steven Johnson:

  - Add a NoClean() Environment method and function to override removal
    of targets during a -c clean, including documentation and tests.

  From Steven Knight:

  - Check for whether files exist on disk by listing the directory
    contents, not calling os.path.exists() file by file.  This is
    somewhat more efficient in general, and may be significantly
    more efficient on Windows.

  - Minor speedups in the internal is_Dict(), is_List() and is_String()
    functions.

  - Fix a signature refactoring bug that caused Qt header files to
    get re-generated every time.

  - Don't fail when writing signatures if the .sconsign.dblite file is
    owned by a different user (e.g. root) from a previous run.

  - When deleting variables from stacked OverrideEnvironments, don't
    throw a KeyError if we were able to delte the variable from any
    Environment in the stack.

  - Get rid of the last indentation tabs in the SCons source files and
    add -tt to the Python invocations in the packaging build and the
    tests so they don't creep back in.

  - In Visual Studio project files, put quotes around the -C directory
    so everything works even if the path has spaces in it.

  - The Intel Fortran compiler uses -object:$TARGET, not "-o $TARGET",
    when building object files on Windows.  Have the the ifort Tool
    modify the default command lines appropriately.

  - Document the --debug=explain option in the man page.  (How did we
    miss this?)

  - Add a $LATEXRETRIES variable to allow configuration of the number of
    times LaTex can be re-called to try to resolve undefined references.

  - Change the order of the arguments to Configure.Checklib() to match
    the documentation.

  - Handle signature calculation properly when the Python function used
    for a FunctionAction is an object method.

  - On Windows, assume that absolute path names without a drive letter
    refer to the drive on which the SConstruct file lives.

  - Add /usr/ccs/bin to the end of the the default external execution
    PATH on Solaris.

  - Add $PKGCHK and $PKGINFO variables for use on Solaris when searching
    for the SunPRO C++ compiler.  Make the default value for $PKGCHK
    be /usr/sbin/pgkchk (since /usr/sbin isn't usually on the external
    execution $PATH).

  - Fix a man page example of overriding variables when calling
    SharedLibrary() to also set the $LIBSUFFIXES variable.

  - Add a --taskmastertrace=FILE option to give some insight on how
    the taskmaster decides what Node to build next.

  - Changed the names of the old $WIN32DEFPREFIX, $WIN32DEFSUFFIX,
    $WIN32DLLPREFIX and $WIN32IMPLIBPREFIX construction variables to
    new $WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX, $WINDOWSDLLPREFIX and
    $WINDOWSIMPLIBPREFIX construction variables.  The old names are now
    deprecated, but preserved for backwards compatibility.

  - Fix (?) a runtest.py hang on Windows when the --xml option is used.

  - Change the message when an error occurs trying to interact with the
    file system to report the target(s) in square brackets (as before) and
    the actual file or directory that encountered the error afterwards.

  From Chen Lee:

  - Add x64 support for Microsoft Visual Studio 8.

  From Baptiste Lepilleur:

  - Support the --debug=memory option on Windows when the Python version
    has the win32process and win32api modules.

  - Add support for Visual Studio 2005 Pro.

  - Fix portability issues in various tests: test/Case.py,
    Test/Java/{JAR,JARCHDIR,JARFLAGS,JAVAC,JAVACFLAGS,JAVAH,RMIC}.py,
    test/MSVS/vs-{6.0,7.0,7.1,8.0}-exec.py,
    test/Repository/{Java,JavaH,RMIC}.py,
    test/QT/{generated-ui,installed,up-to-date,warnings}.py,
    test/ZIP/ZIP.py.

  - Ignore pkgchk errors on Solaris when searching for the C++ compiler.

  - Speed up the SCons/EnvironmentTests.py unit tests.

  - Add a --verbose= option to runtest.py to print executed commands
    and their output at various levels.

  From Christian Maaser:

  - Add support for Visual Studio Express Editions.

  - Add support for Visual Studio 8 *.manifest files, includng
    new $WINDOWS_INSERT_MANIFEST, $WINDOWSPROGMANIFESTSUFFIX,
    $WINDOWSPROGMANIFESTPREFIX, $WINDOWSPROGMANIFESTSUFFIX,
    $WINDOWSSHLIBMANIFESTPREFIX and $WINDOWSSHLIBMANIFESTSUFFIX
    construction variables.

  From Adam MacBeth:

  - Fix detection of additional Java inner classes following use of a
    "new" keyword inside an inner class.

  From Sanjoy Mahajan:

  - Correct TeX-related command lines to just $SOURCE, not $SOURCES

  From Patrick Mezard:

  - Execute build commands for a command-line target if any of the
    files built along with the target is out of date or non-existent,
    not just if the command-line target itself is out of date.

  - Fix the -n option when used with -c to print all of the targets
    that will be removed for a multi-target Builder call.

  - If there's no file in the source directory, make sure there isn't
    one in the build directory, too, to avoid dangling files left
    over from previous runs when a source file is removed.

  - Allow AppendUnique() and PrependUnique() to append strings (and
    other atomic objects) to lists.

  From Joel B. Mohler:

  - Extend latex.py, pdflatex.py, pdftex.py and tex.py so that building
    from both TeX and LaTeX files uses the same logic to call $BIBTEX
    when it's necessary, to call $MAKEINDEX when it's necessary, and to
    call $TEX or $LATEX multiple times to handle undefined references.

  - Add an emitter to the various TeX builders so that the generated
    .aux and .log files also get deleted by the -c option.

  From Leanid Nazdrynau:

  - Fix the Qt UIC scanner to work with generated .ui files (by using
    the FindFile() function instead of checking by-hand for the file).

  From Jan Nieuwenhuizen:

  - Fix a problem with interpreting quoted argument lists on command lines.

  From Greg Noel:

  - Add /sw/bin to the default execution PATH on Mac OS X.

  From Kian Win Ong:

  - When building a .jar file and there is a $JARCHDIR, put the -C
    in front of each .class file on the command line.

  - Recognize the Java 1.5 enum keyword.

  From Asfand Yar Qazi:

  - Add /opt/bin to the default execution PATH on all POSIX platforms
    (between /usr/local/bin and /bin).

  From Jon Rafkind:

  - Fix the use of Configure() contexts from nested subsidiary
    SConscript files.

  From Christoph Schulz:

  - Add support for $CONFIGUREDIR and $CONFIGURELOG variables to control
    the directory and logs for configuration tests.

  - Add support for a $INSTALLSTR variable.

  - Add support for $RANLIBCOM and $RANLIBCOMSTR variables (which fixes
    a bug when setting $ARCOMSTR).

  From Amir Szekely:

  - Add use of $CPPDEFINES to $RCCOM (resource file compilation) on MinGW.

  From Erick Tryzelaar:

  - Fix the error message when trying to report that a given option is
    not gettable/settable from an SConscript file.

  From Dobes Vandermeer:

  - Add support for SCC and other settings in Microsoft Visual
    Studio project and solution files:  $MSVS_PROJECT_BASE_PATH,
    $MSVS_PROJECT_GUID, $MSVS_SCC_AUX_PATH, $MSVS_SCC_LOCAL_PATH,
    $MSVS_SCC_PROJECT_NAME, $MSVS_SCC_PROVIDER,

  - Add support for using a $SCONS_HOME variable (imported from the
    external environment, or settable internally) to put a shortened
    SCons execution line in the Visual Studio project file.

  From David J. Van Maren:

  - Only filter common prefixes from source files names in Visual Studio
    project files if the prefix is a complete (sub)directory name.

  From Thad Ward:

  - If $MSVSVERSIONS is already set, don't overwrite it with
    information from the registry.



RELEASE 0.96.91 - Thu, 08 Sep 2005 07:18:23 -0400

  NOTE:  This was a pre-release of 0.97 for testing purposes.

  From Chad Austin:

  - Have the environment store the toolpath and re-use it to find Tools
    modules during later Copy() or Tool() calls (unless overridden).

  - Normalize the directory path names in SConsignFile() database
    files so the same signature file can interoperate on Windows and
    non-Windows systems.

  - Make --debug=stacktrace print a stacktrace when a UserError is thrown.

  - Remove an old, erroneous cut-and-paste comment in Scanner/Dir.py.

  From Stanislav Baranov:

  - Make it possible to support with custom Alias (sub-)classes.

  - Allow Builders to take empty source lists when called.

  - Allow access to both TARGET and SOURCE in $*PATH expansions.

  - Allow SConscript files to modify BUILD_TARGETS.

  From Timothee Besset:

  - Add support for Objective C/C++ .m and .mm file suffixes (for
    Mac OS X).

  From Charles Crain

  - Fix the PharLap linkloc.py module to use target+source arguments
    when calling env.subst().

  From Bjorn Eriksson:

  - Fix an incorrect Command() keyword argument in the man page.

  - Add a $TEMPFILEPREFIX variable to control the prefix or flag used
    to pass a long-command-line-execution tempfile to a command.

  From Steven Knight:

  - Enhanced the SCons setup.py script to install man pages on
    UNIX/Linux systems.

  - Add support for an Options.FormatOptionHelpText() method that can
    be overridden to customize the format of Options help text.

  - Add a global name for the Entry class (which had already been
    documented).

  - Fix re-scanning of generated source files for implicit dependencies
    when the -j option is used.

  - Fix a dependency problem that caused $LIBS scans to not be added
    to all of the targets in a multiple-target builder call, which
    could cause out-of-order builds when the -j option is used.

  - Store the paths of source files and dependencies in the .sconsign*
    file(s) relative to the target's directory, not relative to the
    top-level SConstruct directory.  This starts to make it possible to
    subdivide the dependency tree arbitrarily by putting an SConstruct
    file in every directory and using content signatures.

  - Add support for $YACCHFILESUFFIX and $YACCHXXFILESUFFIX variables
    that accomodate parser generators that write header files to a
    different suffix than the hard-coded .hpp when the -d option is used.

  - The default behavior is now to store signature information in a
    single .sconsign.dblite file in the top-level SConstruct directory.
    The old behavior of a separate .sconsign file in each directory can
    be specified by calling SConsignFile(None).

  - Remove line number byte codes within the signature calculation
    of Python function actions, so that changing the location of an
    otherwise unmodified Python function doesn't cause rebuilds.

  - Fix AddPreAction() and AddPostAction() when an action has more than
    one target file:  attach the actions to the Executor, not the Node.

  - Allow the source directory of a BuildDir / build_dir to be outside
    of the top-level SConstruct directory tree.

  - Add a --debug=nomemoizer option that disables the Memoizer for clearer
    looks at the counts and profiles of the underlying function calls,
    not the Memoizer wrappers.

  - Print various --debug= stats even if we exit early (e.g. using -h).

  - Really only use the cached content signature value if the file
    is older than --max-drift, not just if --max-drift is set.

  - Remove support for conversion from old (pre 0.96) .sconsign formats.

  - Add support for a --diskcheck option to enable or disable various
    on-disk checks:  that File and Dir nodes match on-disk entries;
    whether an RCS file exists for a missing source file; whether an
    SCCS file exists for a missing source file.

  - Add a --raw argument to the sconsign script, so it can print a
    raw representation of each entry's NodeInfo dictionary.

  - Add the 'f90' and 'f95' tools to the list of Fortran compilers
    searched for by default.

  - Add the +Z option by default when compiling shared objects on
    HP-UX.

  From Chen Lee:

  - Handle Visual Studio project and solution files in Unicode.

  From Sanjoy Mahajan:

  - Fix a bad use of Copy() in an example in the man page, and a
    bad regular expression example in the man page and User's Guide.

  From Shannon Mann:

  - Have the Visual Studio project file(s) echo "Starting SCons" before
    executing SCons, mainly to work around a quote-stripping bug in
    (some versions of?) the Windows cmd command executor.

  From Georg Mischler:

  - Remove the space after the -o option when invoking the Borland
    BCC compiler; some versions apparently require that the file name
    argument be concatenated with the option.

  From Leanid Nazdrynau:

  - Fix the Java parser's handling of backslashes in strings.

  From Greg Noel:

  - Add construction variables to support frameworks on Mac OS X:
    $FRAMEWORKS, $FRAMEWORKPREFIX, $FRAMEWORKPATH, $FRAMEWORKPATHPREFIX.

  - Re-order link lines so the -o option always comes right after the
    command name.

  From Gary Oberbrunner:

  - Add support for Intel C++ beta 9.0 (both 32 and 64 bit versions).

  - Document the new $FRAMEWORK* variables for Mac OS X.

  From Karol Pietrzak:

  - Add $RPATH (-R) support to the Sun linker Tool (sunlink).

  - Add a description of env.subst() to the man page.

  From Chris Prince:

  - Look in the right directory, not always the local directory, for a
    same-named file or directory conflict on disk.

  - On Windows, preserve the external environment's %SYSTEMDRIVE%
    variable, too.

  From Craig Scott:

  - Have the Fortran module emitter look for Fortan modules to be created
    relative to $FORTRANMODDIR, not the top-level directory.

  - When saving Options to a file, run default values through the
    converter before comparing them with the set values.  This correctly
    suppresses Boolean Option values from getting written to the saved
    file when they're one of the many synonyms for a default True or
    False value.

  - Fix the Fortran Scanner's ability to handle a module being used
    in the same file in which it is defined.

  From Steve-o:

  - Add the -KPIC option by default when compiling shared objects on
    Solaris.

  - Change the default suffix for Solaris objects to .o, to conform to
    Sun WorkShop's expectations.  Change the profix to so_ so they can
    still be differentiated from static objects in the same directory.

  From Amir Szekely:

  - When calling the resource compiler on MinGW, add --include-dir and
    the source directory so it finds the source file.

  - Update EnsureSConsVersion() to support revision numbers.

  From Greg Ward:

  - Fix a misplaced line in the man page.



RELEASE 0.96.90 - Tue, 15 Feb 2005 21:21:12 +0000

  NOTE:  This was a pre-release of 0.97 for testing purposes.

  From Anonymous:

  - Fix Java parsing to avoid erroneously identifying a new array
    of class instances as an anonymous inner class.

  - Fix a typo in the man page description of PathIsDirCreate.

  From Chad Austin:

  - Allow Help() to be called multiple times, appending to the help
    text each call.

  - Allow Tools found on a toolpath to import Python modules from
    their local directory.

  From Steve Christensen:

  - Handle exceptions from Python functions as build actions.

  - Add a set of canned PathOption validators:  PathExists (the default),
    PathIsFile, PathIsDir and PathIsDirCreate.

  From Matthew Doar:

  - Add support for .lex and .yacc file suffixes for Lex and Yacc files.

  From Eric Frias:

  - Huge performance improvement:  wrap the tuples representing an
    include path in an object, so that the time it takes to hash the
    path doesn't grow porportionally to the length of the path.

  From Gottfried Ganssauge:

  - Fix SCons on SuSE/AMD-64 Linux by having the wrapper script also
    check for the build engine in the parent directory of the Python
    library directory (/usr/lib64 instead of /usr/lib).

  From Stephen Kennedy:

  - Speed up writing the .sconsign file at the end of a run by only
    calling sync() once at the end, not after every entry.

  From Steven Knight:

  - When compiling with Microsoft Visual Studio, don't include the ATL and
    MFC directories in the default INCLUDE and LIB environment variables.

  - Remove the following deprecated features:  the ParseConfig()
    global function (deprecated in 0.93); the misspelled "validater"
    keyword to the Options.Add() method (deprecated in 0.91); the
    SetBuildSignatureType(), SetContentSignatureType(), SetJobs() and
    GetJobs() global functions (deprecated in 0.14).

  - Fix problems with corrupting the .sconsign.dblite file when
    interrupting builds by writing to a temporary file and renaming,
    not writing the file directly.

  - Fix a 0.96 regression where when running with -k, targets built from
    walking dependencies later on the command line would not realize
    that a dependency had failed an earlier build attempt, and would
    try to rebuild the dependent targets.

  - Change the final messages when using -k and errors occur from
    "{building,cleaning} terminated because of errors" to "done
    {building,cleaning} targets (errors occurred during {build,clean})."

  - Allow Configure.CheckFunc() to take an optional header argument
    (already supported by Conftest.py) to specify text at the top of
    the compiled test file.

  - Fix the --debug=explain output when a Python function action changed
    so it prints a meaningful string, not the binary representation of
    the function contents.

  - Allow a ListOption's default value(s) to be a Python list of specified
    values, not just a string containing a comma-separated list of names.

  - Add a ParseDepends() function that will parse up a list of explicit
    dependencies from a "make depend" style file.

  - Support the ability to change directory when executing an Action
    through "chdir" keyword arguments to Action and Builder creation
    and calls.

  - Fix handling of Action ojects (and other callables that don't match
    our calling arguments) in construction variable expansions.

  - On Win32, install scons.bat in the Python directory when installing
    from setup.py.  (The bdist_wininst installer was already doing this.)

  - Fix env.SConscript() when called with a list of SConscipt files.
    (The SConscript() global function already worked properly.)

  - Add a missing newline to the end of the --debug=explain "unknown
    reasons" message.

  - Enhance ParseConfig() to work properly for spaces in between the -I,
    -L and -l options and their arguments.

  - Packaging build fix:  Rebuild the files that are use to report the
    --version of SCons whenever the development version number changes.

  - Fix the ability to specify a target_factory of Dir() to a Builder,
    which the default create-a-directory Builder was interfering with.

  - Mark a directory as built if it's created as part of the preparation
    for another target, to avoid trying to build it again when it comes
    up in the target list.

  - Allow a function with the right calling signature to be put directly
    in an Environment's BUILDERS dictionary, making for easier creation
    and use of wrappers (pseudo-Builders) that call other Builders.

  - On Python 2.x, wrap lists of Nodes returned by Builders in a UserList
    object that adds a method that makes str() object return a string
    with all of the Nodes expanded to their path names.  (Builders under
    Python 1.5.2 still return lists to avoid TypeErrors when trying
    to extend() list, so Python 1.5.2 doesn't get pretty-printing of Node
    lists, but everything should still function.)

  - Allow Aliases to have actions that will be executed whenever
    any of the expanded Alias targets are out of date.

  - Fix expansion of env.Command() overrides within target and
    source file names.

  - Support easier customization of what's displayed by various default
    actions by adding lots of new construction variables: $ARCOMSTR,
    $ASCOMSTR, $ASPPCOMSTR, $BIBTEXCOMSTR, $BITKEEPERCOMSTR, $CCCOMSTR,
    $CVSCOMSTR, $CXXCOMSTR, $DCOMSTR, $DVIPDFCOMSTR, $F77COMSTR,
    $F90COMSTR, $F95COMSTR, $FORTRANCOMSTR, $GSCOMSTR, $JARCOMSTR,
    $JAVACCOMSTR, $JAVAHCOMSTR, $LATEXCOMSTR, $LEXCOMSTR, $LINKCOMSTR,
    $M4COMSTR, $MIDLCOMSTR, $P4COMSTR, $PCHCOMSTR, $PDFLATEXCOMSTR,
    $PDFTEXCOMSTR, $PSCOMSTR, $QT_MOCFROMCXXCOMSTR, $QT_MOCFROMHCOMSTR,
    $QT_UICCOMSTR, $RCCOMSTR, $REGSVRCOMSTR, $RCS_COCOMSTR, $RMICCOMSTR,
    $SCCSCOMSTR, $SHCCCOMSTR, $SHCXXCOMSTR, $SHF77COMSTR, $SHF90COMSTR,
    $SHF95COMSTR, $SHFORTRANCOMSTR, $SHLINKCOMSTR, $SWIGCOMSTR,
    $TARCOMSTR, $TEXCOMSTR, $YACCCOMSTR and $ZIPCOMSTR.

  - Add an optional "map" keyword argument to ListOption() that takes a
    dictionary to map user-specified values to legal values from the list
    (like EnumOption() already doee).

  - Add specific exceptions to try:-except: blocks without any listed,
    so that they won't catch and mask keyboard interrupts.

  - Make --debug={tree,dtree,stree} print something even when there's
    a build failure.

  - Fix how Scanners sort the found dependencies so that it doesn't
    matter whether the dependency file is in a Repository or not.
    This may cause recompilations upon upgrade to this version.

  - Make AlwaysBuild() work with Alias and Python value Nodes (making
    it much simpler to support aliases like "clean" that just invoke
    an arbitrary action).

  - Have env.ParseConfig() use AppendUnique() by default to suppress
    duplicate entries from multiple calls.  Add a "unique" keyword
    argument to allow the old behavior to be specified.

  - Allow the library modules imported by an SConscript file to get at
    all of the normally-available global functions and variables by saying
    "from SCons.Script import *".

  - Add a --debug=memoizer option to print Memoizer hit/mass statistics.

  - Allow more than one --debug= option to be set at a time.

  - Change --debug=count to report object counts before and after
    reading SConscript files and before and after building targets.

  - Change --debug=memory output to line up the numbers and to better
    match (more or less) the headers on the --debug=count columns.

  - Speed things up when there are lists of targets and/or sources by
    getting rid of some N^2 walks of the lists involved.

  - Cache evaluation of LazyActions so we don't create a new object
    for each invocation.

  - When scanning, don't create Nodes for include files that don't
    actually exist on disk.

  - Make supported global variables CScanner, DScanner, ProgramScanner and
    SourceFileScanner.  Make SourceFileScanner.add_scanner() a supported
    part of the public interface.  Keep the old SCons.Defaults.*Scan names
    around for a while longer since some people were already using them.

  - By default, don't scan directories for on-disk files.  Add a
    DirScanner global scanner that can be used in Builders or Command()
    calls that want source directory trees scanned for on-disk changes.
    Have the Tar() and Zip() Builders use the new DirScanner to preserve
    the behavior of rebuilding a .tar or .zip file if any file or
    directory under a source tree changes.  Add Command() support for
    a source_scanner keyword argument to Command() that can be set to
    DirScanner to get this behavior.

  - Documentation changes:  Explain that $CXXFLAGS contains $CCFLAGS
    by default.  Fix a bad target_factory example in the man page.
    Add appendices to the User's Guide to cover the available Tools,
    Builders and construction variables.  Comment out the build of
    the old Python 10 paper, which doesn't build on all systems and
    is old enough at this point that it probably isn't worth the
    effort to make it do so.

  From Wayne Lee:

  - Avoid "maximum recursion limit" errors when removing $(-$) pairs
    from long command lines.

  From Clive Levinson:

  - Make ParseConfig() recognize and add -mno-cygwin to $LINKFLAGS and
    $CCFLAGS, and -mwindows to $LINKFLAGS.

  From Michael McCracken:

  - Add a new "applelink" tool to handle the things like Frameworks and
    bundles that Apple has added to gcc for linking.

  - Use more appropriate default search lists of linkers, compilers and
    and other tools for the 'darwin' platform.

  - Add a LoadableModule Builder that builds a bundle on Mac OS X (Darwin)
    and a shared library on other systems.

  - Improve SWIG tests for use on Mac OS X (Darwin).

  From Elliot Murphy:

  - Enhance the tests to guarantee persistence of ListOption
    values in saved options files.

  - Supply the help text when -h is used with the -u, -U or -D options.

  From Christian Neeb:

  - Fix the Java parser's handling of string definitions to avoid ignoring
    subsequent code.

  From Han-Wen Nienhuys:

  - Optimize variable expansion by:  using the re.sub() method (when
    possible); not using "eval" for variables for which we can fetch the
    value directory; avoiding slowing substitution logic when there's no
    '$' in the string.

  From Gary Oberbrunner:

  - Add an Environment.Dump() method to print the contents of a
    construction environment.

  - Allow $LIBS (and similar variables) to contain explicit File Nodes.

  - Change ParseConfig to add the found library names directly to the
    $LIBS variable, instead of returning them.

  - Add ParseConfig() support for the -framework GNU linker option.

  - Add a PRINT_CMD_LINE_FUNC construction variable to allow people
    to filter (or log) command-line output.

  - Print an internal Python stack trace in response to an otherwise
    unexplained error when --debug=stacktrace is specified.

  - Add a --debug=findlibs option to print what's happening when
    the scanner is searching for libraries.

  - Allow Tool specifications to be passed a dictionary of keyword
    arguments.

  - Support an Options default value of None, in which case the variable
    will not be added to the construction environment unless it's set
    explicitly by the user or from an Options file.

  - Avoid copying __builtin__ values into a construction environment's
    dictionary when evaluating construction variables.

  - Add a new cross-platform intelc.py Tool that can detect and
    configure the Intel C++ v8 compiler on both Windows, where it's
    named icl, and Linux, where it's named icc.  It also checks that
    the directory specified in the Windows registry exists, and sets a
    new $INTEL_C_COMPILER_VERSION construction variable to identify the
    version being used.  (Niall Douglas contributed an early prototype
    of parts of this module.)

  - Fix the private Conftest._Have() function so it doesn't change
    non-alphanumeric characters to underscores.

  - Supply a better error message when a construction variable expansion
    has an unknown attribute.

  - Documentation changes:  Update the man page to describe use of
    filenames or Nodes in $LIBS.

  From Chris Pawling:

  - Have the linkloc tool use $MSVS_VERSION to select the Microsoft
    Visual Studio version to use.

  From Kevin Quick:

  - Fix the Builder name returned from ListBuilders and other instances
    of subclasses of the BuilderBase class.

  - Add Builders and construction variables to support rpcgen:
    RPCGenClient(), RPCGenHeader(), RPCGenService(), RPCGenXDR(),
    $RPCGEN, $RPCGENFLAGS, $RPCGENCLIENTFLAGS, $RPCGENHEADERFLAGS,
    $RPCGENSERVICEFLAGS, $RPCGENXDRFLAGS.

  - Update the man page to document that prefix and suffix Builder
    keyword arguments can be strings, callables or dictionaries.

  - Provide more info in the error message when a user tries to build
    a target multiple ways.

  - Fix Delete() when a file doesn't exist and must_exist=1.  (We were
    unintentionally dependent on a bug in versions of the Python shutil.py
    module prior to Python 2.3, which would generate an exception for
    a nonexistent file even when ignore_errors was set.)

  - Only replace a Node's builder with a non-null source builder.

  - Fix a stack trace when a suffix selection dictionary is passed
    an empty source file list.

  - Allow optional names to be attached to Builders, for default
    Builders that don't get attached to construction environments.

  - Fix problems with Parallel Task Exception handling.

  - Build targets in an associated BuildDir even if there are targets
    or subdirectories locally in the source directory.

  - If a FunctionAction has a callable class as its underlying Python
    function, use its strfunction() method (if any) to display the
    action.

  - Fix handling when BuildDir() exists but is unwriteable.  Add
    "Stop." to those error messages for consistency.

  - Catch incidents of bad builder creation (without an action) and
    supply meaningful error messages.

  - Fix handling of src_suffix values that aren't extensions (don't
    begin with a '.').

  - Don't retrieve files from a CacheDir, but report what would happen,
    when the -n option is used.

  - Use the source_scanner from the target Node, not the source node
    itself.

  - Internal Scanners fixes:  Make sure Scanners are only passed Nodes.
    Fix how a Scanner.Selector called its base class initialization.
    Make comparisons of Scanner objects more robust.  Add a name to
    an internal default ObjSourceScanner.

  - Add a deprecated warning for use of the old "scanner" keyword argument
    to Builder creation.

  - Improve the --debug=explain message when the build action changes.

  - Test enhancements in SourceCode.py, option-n.py, midl.py.  Better
    Command() and Scanner test coverage.  Improved test infrastructure
    for -c output.

  - Refactor the interface between Action and Executor objects to treat
    Actions atomically.

  - The --debug=presub option will now report the pre-substitution
    each action seprately, instead of reporting the entire list before
    executing the actions one by one.

  - The --debug=explain option explaining a changed action will now
    (more correctly) show pre-substitution action strings, instead of
    the commands with substituted file names.

  - A Node (file) will now be rebuilt if its PreAction or PostAction
    actions change.

  - Python Function actions now have their calling signature (target,
    source, env) reported correctly when displayed.

  - Fix BuildDir()/build_dir handling when the build_dir is underneath
    the source directory and trying to use entries from the build_dir
    as sources for other targets in the build-dir.

  - Fix hard-coding of JDK path names in various Java tests.

  - Handle Python stack traces consistently (stop at the SConscript stack
    frame, by default) even if the Python source code isn't available.

  - Improve the performance of the --debug={tree,dtree} options.

  - Add --debug=objects logging of creation of OverrideWarner,
    EnvironmentCopy and EnvironmentOverride objects.

  - Fix command-line expansion of Python Value Nodes.

  - Internal cleanups:  Remove an unnecessary scan argument.  Associate
    Scanners only with Builders, not nodes.  Apply overrides once when
    a Builder is called, not in multiple places.  Cache results from the
    Node.FS.get_suffix() and Node.get_build_env() methods.  Use the Python
    md5 modules' hexdigest() method, if there is one.  Have Taskmaster
    call get_stat() once for each Node and re-use the value instead of
    calling it each time it needs the value.  Have Node.depends_on()
    re-use the list from the children() method instead of calling it
    multiple times.

  - Use the correct scanner if the same source file is used for targets in
    two different environments with the same path but different scanners.

  - Collect logic for caching values in memory in a Memoizer class,
    which cleans up a lot of special-case code in various methods and
    caches additional values to speed up most configurations.

  - Add a PathAccept validator to the list of new canned PathOption
    validators.

  From Jeff Squyres:

  - Documentation changes:  Use $CPPDEFINES instead of $CCFLAGS in man
    page examples.

  From Levi Stephen:

  - Allow $JARCHDIR to be expanded to other construction variables.

  From Christoph Wiedemann:

  - Add an Environment.SetDefault() method that only sets values if
    they aren't already set.

  - Have the qt.py Tool not override variables already set by the user.

  - Add separate $QT_BINPATH, $QT_CPPPATH and $QT_LIBPATH variables
    so these can be set individually, instead of being hard-wired
    relative to $QTDIR.

  - The %TEMP% and %TMP% external environment variables are now propagated
    automatically to the command execution environment on Windows systems.

  - A new --config= command-line option allows explicit control of
    of when the Configure() tests are run:  --config=force forces all
    checks to be run, --config=cache uses all previously cached values,
    --config=auto (the default) runs tests only when dependency analysis
    determines it's necessary.

  - The Configure() subsystem can now write a config.h file with values
    like HAVE_STDIO_H, HAVE_LIBM, etc.

  - The Configure() subsystem now executes its checks silently when the
    -Q option is specified.

  - The Configure() subsystem now reports if a test result is being
    taken from cache, and prints the standard output and error output
    of tests even when cached.

  - Configure() test results are now reported as "yes" or "no" instead of
    "ok" or "failed."

  - Fixed traceback printing when calling the env.Configure() method
    instead of the Configure() global function.

  - The Configure() subsystem now caches build failures in a .sconsign
    file in the subdirectory, not a .cache file.  This may cause
    tests to be re-executed the first time after you install 0.97.

  - Additional significant internal cleanups in the Configure() subsystem
    and its tests.

  - Have the Qt Builder make uic-generated files dependent on the .ui.h
    file, if one exists.

  - Add a test to make sure that SCons source code does not contain
    try:-except: blocks that catch all errors, which potentially catch
    and mask keyboard interrupts.

  - Fix us of TargetSignatures('content') with the SConf subsystem.

  From Russell Yanofsky:

  - Add support for the Metrowerks Codewarrior compiler and linker
    (mwcc and mwld).



RELEASE 0.96.1 - Mon, 23 Aug 2004 12:55:50 +0000

  From Craig Bachelor:

  - Handle white space in the executable Python path name within in MSVS
    project files by quoting the path.

  - Correct the format of a GUID string in a solution (.dsw) file so
    MSVS can correctly "build enable" a project.

  From Steven Knight:

  - Add a must_exist flag to Delete() to let the user control whether
    it's an error if the specified entry doesn't exist.  The default
    behavior is now to silently do nothing if it doesn't exist.

  - Package up the new Platform/darwin.py, mistakenly left out of 0.96.

  - Make the scons.bat REM statements into @REM so they aren't printed.

  - Make the SCons packaging SConscript files platform independent.

  From Anthony Roach:

  - Fix scanning of pre-compiled header (.pch) files for #includes,
    broken in 0.96.



RELEASE 0.96 - Wed, 18 Aug 2004 13:36:40 +0000

  From Chad Austin:

  - Make the CacheDir() directory if it doesn't already exist.

  - Allow construction variable substitutions in $LIBS specifications.

  - Allow the emitter argument to a Builder() to be or expand to a list
    of emitter functions, which will be called in sequence.

  - Suppress null values in construction variables like $LIBS that use
    the internal _concat() function.

  - Remove .dll files from the construction variables searched for
    libraries that can be fed to Win32 compilers.

  From Chad Austin and Christoph Wiedemann:

  - Add support for a $RPATH variable to supply a list of directories
    to search for shared libraries when linking a program.  Used by
    the GNU and IRIX linkers (gnulink and sgilink).

  From Charles Crain:

  - Restore the ability to do construction variable substitutions in all
    kinds of *PATH variables, even when the substitution returns a Node
    or other object.

  From Tom Epperly:

  - Allow the Java() Builder to take more than one source directory.

  From Ralf W. Grosse-Kunstleve:

  - Have SConsignFile() use, by default, a custom "dblite.py" that we can
    control and guarantee to work on all Python versions (or nearly so).

  From Jonathan Gurley:

  - Add support for the newer "ifort" versions of the Intel Fortran
    Compiler for Linux.

  From Bob Halley:

  - Make the new *FLAGS variable type work with copied Environments.

  From Chris Hoeppler:

  - Initialize the name of a Scanner.Classic scanner correctly.

  From James Juhasz:

  - Add support for the .dylib shared library suffix and the -dynamiclib
    linker option on Mac OS X.

  From Steven Knight:

  - Add an Execute() method for executing actions directly.

  - Support passing environment override keyword arguments to Command().

  - Fix use of $MSVS_IGNORE_IDE_PATHS, which was broken when we added
    support for $MSVS_USE_MFC_DIRS last release.

  - Make env.Append() and env.Prepend() act like the underlying Python
    behavior when the variable being appended to is a UserList object.

  - Fix a regression that prevented the Command() global function in
    0.95 from working with command-line strings as actions.

  - Fix checking out a file from a source code management system when
    the env.SourceCode() method was called with an individual file name
    or node, not a directory name or node.

  - Enhance the Task.make_ready() method to create a list of the
    out-of-date Nodes for the task for use by the wrapping interface.

  - Allow Scanners to pull the list of suffixes from the construction
    environment when the "skeys" keyword argument is a string containing
    a construction variable to be expanded.

  - Support new $CPPSUFFIXES, $DSUFFIXES $FORTRANSUFFIXES, and
    $IDLSUFFIXES.  construction variables that contain the default list
    of suffixes to be scanned by a given type of scanner, allowing these
    suffix lists to be easily added to or overridden.

  - Speed up Node creation when calling a Builder by comparing whether two
    Environments are the same object, not if their underlying dictionaries
    are equivalent.

  - Add a --debug=explain option that reports the reason(s) why SCons
    thinks it must rebuild something.

  - Add support for functions that return platform-independent Actions
    to Chmod(), Copy(), Delete(), Mkdir(), Move() and Touch() files
    and/or directories.  Like any other Actions, the returned Action
    object may be executed directly using the Execute() global function
    or env.Execute() environment method, or may be used as a Builder
    action or in an env.Command() action list.

  - Add support for the strfunction argument to all types of Actions:
    CommandAction, ListAction, and CommandGeneratorAction.

  - Speed up turning file system Nodes into strings by caching the
    values after we're finished reading the SConscript files.

  - Have ParseConfig() recognize and supporting adding the -Wa, -Wl,
    and -Wp, flags to ASFLAGS, LINKFLAGS and CPPFLAGS, respectively.

  - Change the .sconsign format and the checks for whether a Node is
    up-to-date to make dependency checks more efficient and correct.

  - Add wrapper Actions to SCons.Defaults for $ASCOM, $ASPPCOM, $LINKCOM,
    $SHLINKCOM, $ARCOM, $LEXCOM and $YACCCOM.  This makes it possible
    to replace the default print behavior with a custom strfunction()
    for each of these.

  - When a Node has been built, don't walk the whole tree back to delete
    the parents's implicit dependencies, let returning up the normal
    Taskmaster descent take care of it for us.

  - Add documented support for separate target_scanner and source_scanner
    arguments to Builder creation, which allows different scanners to
    be applied to source files

  - Don't re-install or (re-generate) .h files when a subsidiary #included
    .h file changes.  This eliminates incorrect circular dependencies
    with .h files generated from other source files.

  - Slim down the internal Sig.Calculator class by eliminating methods
    whose functionality is now covered by Node methods.

  - Document use of the target_factory and source_factory keyword
    arguments when creating Builder objects.  Enhance Dir Nodes so that
    they can be created with user-specified Builder objects.

  - Don't blow up with stack trace when the external $PATH environment
    variable isn't set.

  - Make Builder calls return lists all the time, even if there's only
    one target.  This keeps things consistent and easier to program to
    across platforms.

  - Add a Flatten() function to make it easier to deal with the Builders
    all returning lists of targets, not individual targets.

  - Performance optimizations in Node.FS.__doLookup().

  - Man page fixes:  formatting typos, misspellings, bad example.

  - User's Guide fixes: Fix the signatures of the various example
    *Options() calls.  Triple-quote properly a multi-line Split example.

  - User's Guide additions:  Chapter describing File and Directory
    Nodes.  Section describing declarative nature of SCons functions in
    SConscript files.  Better organization and clarification of points
    raised by Robert P. J. Day.  Chapter describing SConf (Autoconf-like)
    functionality.  Chapter describing how to install Python and
    SCons.  Chapter describing Java builds.

  From Chris Murray:

  - Add a .win32 attribute to force file names to expand with
    Windows backslash path separators.

  - Fix escaping file names on command lines when the expansion is
    concatenated with another string.

  - Add support for Fortran 90 and Fortran 95.  This adds $FORTRAN*
    variables that specify a default compiler, command-line, flags,
    etc. for all Fortran versions, plus separate $F90* and $F95*
    variables for when different compilers/flags/etc. must be specified
    for different Fortran versions.

  - Have individual tools that create libraries override the default
    $LIBPREFIX and $LIBSUFFIX values set by the platform.  This makes
    it easier to use Microsoft Visual Studio tools on a CygWin platform.

  From Gary Oberbrunner:

  - Add a --debug=presub option to print actions prior to substitution.

  - Add a warning upon use of the override keywords "targets" and
    "sources" when calling Builders.  These are usually mistakes which
    are otherwise silently (and confusingly) turned into construction
    variable overrides.

  - Try to find the ICL license file path name in the external environment
    and the registry before resorting to the hard-coded path name.

  - Add support for fetching command-line keyword=value arguments in
    order from an ARGLIST list.

  - Avoid stack traces when trying to read dangling symlinks.

  - Treat file "extensions" that only contain digits as part of the
    file basename.  This supports version numbers as part of shared
    library names, for example.

  - Avoid problems when there are null entries (None or '') in tool
    lists or CPPPATH.

  - Add an example and explanation of how to use "tools = ['default', ..."
    when creating a construction environment.

  - Add a section describing File and Directory Nodes and some of their
    attributes and methods.

  - Have ParseConfig() add a returned -pthread flag to both $CCFLAGS
    and $LINKFLAGS.

  - Fix some test portability issues on Mac OS X (darwin).

  From Simon Perkins:

  - Fix a bug introduced in building shared libraries under MinGW.

  From Kevin Quick:

  - Handling SCons exceptions according to Pythonic standards.

  - Fix test/chained-build.py on systems that execute within one second.

  - Fix tests on systems where 'ar' warns about archive creation.

  From Anthony Roach:

  - Fix use of the --implicit-cache option with timestamp signatures.

  - If Visual Studio is installed, assume the C/C++ compiler, the linker
    and the MIDL compiler that comes with it are available, too.

  - Better error messages when evaluating a construction variable
    expansion yields a Python syntax error.

  - Change the generation of PDB files when using Visual Studio from
    compile time to link time.

  From sam th:

  - Allow SConf.CheckLib() to search a list of libraries, like the
    Autoconf AC_SEARCH_LIBS macro.

  - Allow the env.WhereIs() method to take a "reject" argument to
    let it weed out specific path names.

  From Christoph Wiedemann:

  - Add new Moc() and Uic() Builders for more explicit control over
    Qt builds, plus new construction variables to control them:
    $QT_AUTOSCAN, $QT_DEBUG, $QT_MOCCXXPREFIX, $QT_MOCCXXSUFFIX,
    $QT_MOCHPREFIX, $QT_MOCHSUFFIX, $QT_UICDECLPREFIX, $QT_UICDECLSUFFIX,
    $QT_UICIMPLPREFIX, $QT_UICIMPLSUFFIX and $QT_UISUFFIX.

  - Add a new single_source keyword argument for Builders that enforces
    a single source file on calls to the Builder.



RELEASE 0.95 - Mon, 08 Mar 2004 06:43:20 -0600

  From Chad Austin:

  - Replace print statements with calls to sys.stdout.write() so output
    lines stay together when -j is used.

  - Add portability fixes for a number of tests.

  - Accomodate the fact that Cygwin's os.path.normcase() lies about
    the underlying system being case-sensitive.

  - Fix an incorrect _concat() call in the $RCINCFLAGS definition for
    the mingw Tool.

  - Fix a problem with the msvc tool with Python versions prior to 2.3.

  - Add support for a "toolpath" Tool() and Environment keyword that
    allows Tool modules to be found in specified local directories.

  - Work around Cygwin Python's silly fiction that it's using a
    case-sensitive file system.

  - More robust handling of data in VCComponents.dat.

  - If the "env" command is available, spawn commands with the more
    general "env -" instead of "env -i".

  From Kerim Borchaev:

  - Fix a typo in a msvc.py's registry lookup:  "VCComponents.dat", not
    "VSComponents.dat".

  From Chris Burghart:

  - Fix the ability to save/restore a PackageOption to a file.

  From Steve Christensen:

  - Update the MSVS .NET and MSVC 6.0/7.0 path detection.

  From David M. Cooke:

  - Make the Fortran scanner case-insensitive for the INCLUDE string.

  From Charles Crain:

  - If no version of MSVC is detected but the tool is specified,
    use the MSVC 6.0 paths by default.

  - Ignore any "6.1" version of MSVC found in the registry; this is a
    phony version number (created by later service packs?) and would
    throw off the logic if the user had any non-default paths configure.

  - Correctly detect if the user has independently configured the MSVC
    "include," "lib" or "path" in the registry and use the appropriate
    values.  Previously, SCons would only use the values if all three
    were set in the registry.

  - Make sure side-effect nodes are prepare()d before building their
    corresponding target.

  - Preserve the ability to call BuildDir() multiple times with the
    same target and source directory arguments.

  From Andy Friesen:

  - Add support for the Digital Mars "D" programming language.

  From Scott Lystig Fritchie:

  - Fix the ability to use a custom _concat() function in the
    construction environment when calling _stripixes().

  - Make the message about ignoring a missing SConscript file into a
    suppressable Warning, not a hard-coded sys.stderr.write().

  - If a builder can be called multiple times for a target (because
    the sources and overrides are identical, or it's a builder with the
    "multi" flag set), allow the builder to be called through multiple
    environments so long as the builders have the same signature for
    the environments in questions (that is, they're the same action).

  From Bob Halley:

  - When multiple targets are built by a single action, retrieve all
    of them from cache, not just the first target, and exec the build
    command if any of the targets isn't present in the cache.

  From Zephaniah Hull:

  - Fix command-line ARGUMENTS with multiple = in them.

  From Steven Knight:

  - Fix EnsureSConsVersion() so it checks against the SCons version,
    not the Python version, on Pythons with sys.version_info.

  - Don't swallow the AttributeError when someone uses an expansion like
    $TARGET.bak, so we can supply a more informative error message.

  - Fix an odd double-quote escape sequence in the man page.

  - Fix looking up a naked drive letter as a directory (Dir('C:')).

  - Support using File nodes in the LIBS construction variable.

  - Allow the LIBS construction variable to be a single string or File
    node, not a list, when only one library is needed.

  - Fix typos in the man page:  JAVACHDIR => JARCHDIR; add "for_signature"
    to the __call__() example in the "Variable Substitution" section.

  - Correct error message spellings of "non-existant" to "non-existent."

  - When scanning for libraries to link with, don't append $LIBPREFIXES
    or $LIBSUFFIXES values to the $LIBS values if they're already present.

  - Add a ZIPCOMPRESSION construction variable to control whether the
    internal Python action for the Zip Builder compresses the file or
    not.  The default value is zipfile.ZIP_DEFLATED, which generates
    a compressed file.

  - Refactor construction variable expansion to support recursive
    expansion of variables (e.g. CCFLAGS = "$CCFLAGS -g") without going
    into an infinite loop.  Support this in all construction variable
    overrides, as well as when copying Environments.

  - Fix calling Configure() from more than one subsidiary SConscript file.

  - Fix the env.Action() method so it returns the correct type of
    Action for its argument(s).

  - Fix specifying .class files as input to JavaH with the .class suffix
    when they weren't generated using the Java Builder.

  - Make the check for whether all of the objects going into a
    SharedLibrary() are shared work even if the object was built in a
    previous run.

  - Supply meaningful error messages, not stack traces, if we try to add
    a non-Node as a source, dependency, or ignored dependency of a Node.

  - Generate MSVS Project files that re-invoke SCons properly regardless
    of whether the file was built via scons.bat or scons.py.
    (Thanks to Niall Douglas for contributing code and testing.)

  - Fix TestCmd.py, runtest.py and specific tests to accomodate being
    run from directories whose paths include white space.

  - Provide a more useful error message if a construction variable
    expansion contains a syntax error during evaluation.

  - Fix transparent checkout of implicit dependency files from SCCS
    and RCS.

  - Added new --debug=count, --debug=memory and --debug=objects options.
    --debug=count and --debug=objects only print anything when run
    under Python 2.1 or later.

  - Deprecate the "overrides" keyword argument to Builder() creation
    in favor of using keyword argument values directly (like we do
    for builder execution and the like).

  - Always use the Builder overrides in substitutions, not just if
    there isn't a target-specific environment.

  - Add new "rsrcpath" and "rsrcdir" and attributes to $TARGET/$SOURCE,
    so Builder command lines can find things in Repository source
    directories when using BuildDir.

  - Fix the M4 Builder so that it chdirs to the Repository directory
    when the input file is in the source directory of a BuildDir.

  - Save memory at build time by allowing Nodes to delete their build
    environments after they've been built.

  - Add AppendUnique() and PrependUnique() Environment methods, which
    add values to construction variables like Append() and Prepend()
    do, but suppress any duplicate elements in the list.

  - Allow the 'qt' tool to still be used successfully from a copied
    Environment.  The include and library directories previously ended up
    having the same string re-appended to the end, yielding an incorrect
    path name.

  - Supply a more descriptive error message when the source for a target
    can't be found.

  - Initialize all *FLAGS variables with objects do the right thing with
    appending flags as strings or lists.

  - Make things like ${TARGET.dir} work in *PATH construction variables.

  - Allow a $MSVS_USE_MFC_DIRS construction variable to control whether
    ATL and MFC directories are included in the default INCLUDE and
    LIB paths.

  - Document the dbm_module argument to the SConsignFile() function.

  From Vincent Risi:

  - Add support for the bcc32, ilink32 and tlib Borland tools.

  From Anthony Roach:

  - Supply an error message if the user tries to configure a BuildDir
    for a directory that already has one.

  - Remove documentation of the still-unimplemented -e option.

  - Add -H help text listing the legal --debug values.

  - Don't choke if a construction variable is a non-string value.

  - Build Type Libraries in the target directory, not the source
    directory.

  - Add an appendix to the User's Guide showing how to accomplish
    various common tasks in Python.

  From Greg Spencer:

  - Add support for Microsoft Visual Studio 2003 (version 7.1).

  - Evaluate $MSVSPROJECTSUFFIX and $MSVSSOLUTIONSUFFIX when the Builder
    is invoked, not when the tool is initialized.

  From Christoph Wiedemann:

  - When compiling Qt, make sure the moc_*.cc files are compiled using
    the flags from the environment used to specify the target, not
    the environment that first has the Qt Builders attached.



RELEASE 0.94 - Fri, 07 Nov 2003 05:29:48 -0600

  From Hartmut Goebel:

  - Add several new types of canned functions to help create options:
    BoolOption(), EnumOption(), ListOption(), PackageOption(),
    PathOption().

  From Steven Knight:

  - Fix use of CPPDEFINES with C++ source files.

  - Fix env.Append() when the operand is an object with a __cmp__()
    method (like a Scanner instance).

  - Fix subclassing the Environment and Scanner classes.

  - Add BUILD_TARGETS, COMMAND_LINE_TARGETS and DEFAULT_TARGETS variables.

  From Steve Leblanc:

  - SGI fixes:  Fix C++ compilation, add a separate Tool/sgic++.py module.

  From Gary Oberbrunner:

  - Fix how the man page un-indents after examples in some browsers.

  From Vincent Risi:

  - Fix the C and C++ tool specifications for AIX.



RELEASE 0.93 - Thu, 23 Oct 2003 07:26:55 -0500

  From J.T. Conklin:

  - On POSIX, execute commands with the more modern os.spawnvpe()
    function, if it's available.

  - Scan .S, .spp and .SPP files for C preprocessor dependencies.

  - Refactor the Job.Parallel() class to use a thread pool without a
    condition variable.  This improves parallel build performance and
    handles keyboard interrupts properly when -j is used.

  From Charles Crain:

  - Add support for a JARCHDIR variable to control changing to a
    directory using the jar -C option.

  - Add support for detecting Java manifest files when using jar,
    and specifying them using the jar m flag.

  - Fix some Python 2.2 specific things in various tool modules.

  - Support directories as build sources, so that a rebuild of a target
    can be triggered if anything underneath the directory changes.

  - Have the scons.bat and scons.py files look for the SCons modules
    in site-packages as well.

  From Christian Engel:

  - Support more flexible inclusion of separate C and C++ compilers.

  - Use package management tools on AIX and Solaris to find where
    the comilers are installed, and what version they are.

  - Add support for CCVERSION and CXXVERSION variables for a number
    of C and C++ compilers.

  From Sergey Fogel:

  - Add test cases for the new capabilities to run bibtex and to rerun
    latex as needed.

  From Ralf W. Grosse-Kunstleve:

  - Accomodate anydbm modules that don't have a sync() method.

  - Allow SConsignFile() to take an argument specifying the DBM
    module to be used.

  From Stephen Kennedy:

  - Add support for a configurable global .sconsign.dbm file which
    can be used to avoid cluttering each directory with an individual
    .sconsign file.

  From John Johnson:

  - Fix (re-)scanning of dependencies in generated or installed
    header files.

  From Steven Knight:

  - The -Q option suppressed too many messages; fix it so that it only
    suppresses the Reading/Building messages.

  - Support #include when there's no space before the opening quote
    or angle bracket.

  - Accomodate alphanumeric version strings in EnsurePythonVersion().

  - Support arbitrary expansion of construction variables within
    file and directory arguments to Builder calls and Environment methods.

  - Add Environment-method versions of the following global functions:
    Action(), AddPostAction(), AddPreAction(), Alias(), Builder(),
    BuildDir(), CacheDir(), Clean(), Configure(), Default(),
    EnsurePythonVersion(), EnsureSConsVersion(), Environment(),
    Exit(), Export(), FindFile(), GetBuildPath(), GetOption(), Help(),
    Import(), Literal(), Local(), Platform(), Repository(), Scanner(),
    SConscriptChdir(), SConsignFile(), SetOption(), SourceSignatures(),
    Split(), TargetSignatures(), Tool(), Value().

  - Add the following global functions that correspond to the same-named
    Environment methods:  AlwaysBuild(), Command(), Depends(), Ignore(),
    Install(), InstallAs(), Precious(), SideEffect() and SourceCode().

  - Add the following global functions that correspond to the default
    Builder methods supported by SCons: CFile(), CXXFile(), DVI(), Jar(),
    Java(), JavaH(), Library(), M4(), MSVSProject(), Object(), PCH(),
    PDF(), PostScript(), Program(), RES(), RMIC(), SharedLibrary(),
    SharedObject(), StaticLibrary(), StaticObject(), Tar(), TypeLibrary()
    and Zip().

  - Rearrange the man page to show construction environment methods and
    global functions in the same list, and to explain the difference.

  - Alphabetize the explanations of the builder methods in the man page.

  - Rename the Environment.Environment class to Enviroment.Base.
    Allow the wrapping interface to extend an Environment by using its own
    subclass of Environment.Base and setting a new Environment.Environment
    variable as the calling entry point.

  - Deprecate the ParseConfig() global function in favor of a same-named
    construction environment method.

  - Allow the Environment.WhereIs() method to take explicit path and
    pathext arguments (like the underlying SCons.Util.WhereIs() function).

  - Remove the long-obsolete {Get,Set}CommandHandler() functions.

  - Enhance env.Append() to suppress null values when appropriate.

  - Fix ParseConfig() so it works regardless of initial construction
    variable values.

    Extend CheckHeader(), CheckCHeader(), CheckCXXHeader() and
    CheckLibWithHeader() to accept a list of header files that will be
    #included in the test.  The last one in the list is assumed to be
    the one being checked for.  (Prototype code contributed by Gerard
    Patel and Niall Douglas).

  - Supply a warning when -j is used and threading isn't built in to
    the current version of Python.

  - First release of the User's Guide (finally, and despite a lot
    of things still missing from it...).

  From Clark McGrew:

  - Generalize the action for .tex files so that it will decide whether
    a file is TeX or LaTeX, check the .aux output to decide if it should
    run bibtex, and check the .log output to re-run LaTeX if needed.

  From Bram Moolenaar:

  - Split the non-SCons-specific functionality from SConf.py to a new,
    re-usable Conftest.py module.

  From Gary Oberbrunner:

  - Allow a directory to be the target or source or dependency of a
    Depends(), Ignore(), Precious() or SideEffect() call.

  From Gerard Patel:

  - Use the %{_mandir} macro when building our RPM package.

  From Marko Rauhamaa:

  - Have the closing message say "...terminated because of errors" if
    there were any.

  From Anthony Roach:

  - On Win32 systems, only use "rm" to delete files if Cygwin is being
    used.   ("rm" doesn't understand Win32-format path names.)

  From Christoph Wiedemann:

  - Fix test/SWIG.py to find the Python include directory in all cases.

  - Fix a bug in detection of Qt installed on the local system.

  - Support returning Python 2.3 BooleanType values from Configure checks.

  - Provide an error message if someone mistakenly tries to call a
    Configure check from within a Builder function.

  - Support calling a Builder when a Configure context is still open.

  - Handle interrupts better by eliminating all try:-except: blocks
    which caught any and all exceptions, including KeyboardInterrupt.

  - Add a --duplicate= option to control how files are duplicated.



RELEASE 0.92 - Wed, 20 Aug 2003 03:45:28 -0500

  From Charles Crain and Gary Oberbrunner:

  - Fix Tool import problems with the Intel and PharLap linkers.

  From Steven Knight

  - Refactor the DictCmdGenerator class to be a Selector subclass.

  - Allow the DefaultEnvironment() function to take arguments and pass
    them to instantiation of the default construction environment.

  - Update the Debian package so it uses Python 2.2 and more closely
    resembles the currently official Debian packaging info.

  From Gerard Patel

  - When the yacc -d flag is used, take the .h file base name from the
    target .c file, not the source (matching what yacc does).



RELEASE 0.91 - Thu, 14 Aug 2003 13:00:44 -0500

  From Chad Austin:

  - Support specifying a list of tools when calling Environment.Copy().

  - Give a Value Nodes a timestamp of the system time when they're
    created, so they'll work when using timestamp-based signatures.

  - Add a DefaultEnvironment() function that only creates a default
    environment on-demand (for fetching source files, e.g.).

  - Portability fix for test/M4.py.

  From Steven Knight:

  - Tighten up the scons -H help output.

  - When the input yacc file ends in .yy and the -d flag is specified,
    recognize that a .hpp file (not a .h file) will be created.

  - Make builder prefixes work correctly when deducing a target
    from a source file name in another directory.

  - Documentation fixes: typo in the man page; explain up-front about
    not propagating the external environment.

  - Use "cvs co -d" instead of "cvs co -p >" when checking out something
    from CVS with a specified module name.  This avoids zero-length
    files when there is a checkout error.

  - Add an "sconsign" script to print the contents of .sconsign files.

  - Speed up maintaining the various lists of Node children by using
    dictionaries to avoid "x in list" searches.

  - Cache the computed list of Node children minus those being Ignored
    so it's only calculated once.

  - Fix use of the --cache-show option when building a Program()
    (or using any other arbitrary action) by making sure all Action
    instances have strfunction() methods.

  - Allow the source of Command() to be a directory.

  - Better error handling of things like raw TypeErrors in SConscripts.

  - When installing using "setup.py install --prefix=", suppress the
    distutils warning message about adding the (incorrect) library
    directory to your search path.

  - Correct the spelling of the "validater" option to "validator."
    Add a DeprecatedWarning when the old spelling is used.

  - Allow a Builder's emitter to be a dictionary that maps source file
    suffixes to emitter functions, using the suffix of the first file
    in the source list to pick the right one.

  - Refactor the creation of the Program, *Object and *Library Builders
    so that they're moved out of SCons.Defaults and created on demand.

  - Don't split SConscript file names on white space.

  - Document the SConscript function's "dirs" and "name" keywords.

  - Remove the internal (and superfluous) SCons.Util.argmunge() function.

  - Add /TP to the default CXXFLAGS for msvc, so it can compile all
    of the suffixes we use as C++ files.

  - Allow the "prefix" and "suffix" attributes of a Builder to be
    callable objects that return generated strings, or dictionaries
    that map a source file suffix to the right prefix/suffix.

  - Support a MAXLINELINELENGTH construction variable on Win32 systems
    to control when a temporary file is used for long command lines.

  - Make how we build .rpm packages not depend on the installation
    locations from the distutils being used.

  - When deducing a target Node, create it directly from the first
    source Node, not by trying to create the right string to pass to
    arg2nodes().

  - Add support for SWIG.

  From Bram Moolenaar:

  - Test portability fixes for FreeBSD.

  From Gary Oberbrunner:

  - Report the target being built in error messages when building
    multiple sources from different extensions, or when the target file
    extension can't be deduced, or when we don't have an action for a
    file suffix.

  - Provide helpful error messages when the arguments to env.Install()
    are incorrect.

  - Fix the value returned by the Node.prevsiginfo() method to conform
    to a previous change when checking whether a node is current.

  - Supply a stack trace if the Taskmaster catches an exception.

  - When using a temporary file for a long link line on Win32 systems,
    (also) print the command line that is being executed through the
    temporary file.

  - Initialize the LIB environment variable when using the Intel
    compiler (icl).

  - Documentation fixes:  better explain the AlwaysBuild() function.

  From Laurent Pelecq:

  - When the -debug=pdb option is specified, use pdb.Pdb().runcall() to
    call pdb directly, don't call Python recursively.

  From Ben Scott:

  - Add support for a platform-independent CPPDEFINES variable.

  From Christoph Wiedemann:

  - Have the g++ Tool actually use g++ in preference to c++.

  - Have the gcc Tool actually use gcc in preference to cc.

  - Add a gnutools.py test of the GNU tool chain.

  - Be smarter about linking: use $CC by default and $CXX only if we're
    linking with any C++ objects.

  - Avoid SCons hanging when a piped command has a lot of output to read.

  - Add QT support for preprocessing .ui files into .c files.



RELEASE 0.90 - Wed, 25 Jun 2003 14:24:52 -0500

  From Chad Austin:

  - Fix the _concat() documentation, and add a test for it.

  - Portability fixes for non-GNU versions of lex and yacc.

  From Matt Balvin:

  - Fix handling of library prefixes when the subdirectory matches
    the prefix.

  From Timothee Bessett:

  - Add an M4 Builder.

  From Charles Crain:

  - Use '.lnk' as the suffix on the temporary file for linking long
    command lines (necessary for the Phar Lap linkloc linker).

  - Save non-string Options values as their actual type.

  - Save Options string values that contain a single quote correctly.

  - Save any Options values that are changed from the default
    Environment values, not just ones changed on the command line or in
    an Options file.

  - Make closing the Options file descriptor exception-safe.

  From Steven Knight:

  - SCons now enforces (with an error) that construction variables
    must have the same form as valid Python identifiers.

  - Fix man page bugs: remove duplicate AddPostAction() description;
    document no_import_lib; mention that CPPFLAGS does not contain
    $_CPPINCFLAGS; mention that F77FLAGS does not contain $_F77INCFLAGS;
    mention that LINKFLAGS and SHLINKFLAGS contains neither $_LIBFLAGS
    nor $_LIBDIRFLAGS.

  - Eliminate a dependency on the distutils.fancy_getopt module by
    copying and pasting its wrap_text() function directly.

  - Make the Script.Options() subclass match the underlying base class
    implementation.

  - When reporting a target is up to date, quote the target like make
    (backquote-quote) instead of with double quotes.

  - Fix handling of ../* targets when using -U, -D or -u.

  From Steve Leblanc:

  - Don't update the .sconsign files when run with -n.

  From Gary Oberbrunner:

  - Add support for the Intel C Compiler (icl.exe).

  From Anthony Roach

  - Fix Import('*').

  From David Snopek

  - Fix use of SConf in paths with white space in them.

  - Add CheckFunc and CheckType functionality to SConf.

  - Fix use of SConf with Builders that return a list of nodes.

  From David Snopek and Christoph Wiedemann

  - Fix use of the SConf subsystem with SConscriptChdir().

  From Greg Spencer

  - Check for the existence of MS Visual Studio on disk before using it,
    to avoid getting fooled by leftover junk in the registry.

  - Add support for MSVC++ .NET.

  - Add support for MS Visual Studio project files (DSP, DSW,
    SLN and VCPROJ files).

  From Christoph Wiedemann

  - SConf now works correctly when the -n and -q options are used.



RELEASE 0.14 - Wed, 21 May 2003 05:16:32 -0500

  From Chad Austin:

  - Use .dll (not .so) for shared libraries on Cygwin; use -fPIC
    when compiling them.

  - Use 'rm' to remove files under Cygwin.

  - Add a PLATFORM variable to construction environments.

  - Remove the "platform" argument from tool specifications.

  - Propogate PYTHONPATH when running the regression tests so distutils
    can be found in non-standard locations.

  - Using MSVC long command-line linking when running Cygwin.

  - Portability fixes for a lot of tests.

  - Add a Value Node class for dependencies on in-core Python values.

  From Allen Bierbaum:

  - Pass an Environment to the Options validator method, and
    add an Options.Save() method.

  From Steve Christensen:

  - Add an optional sort function argument to the GenerateHelpText()
    Options function.

  - Evaluate the "varlist" variables when computing the signature of a
    function action.

  From Charles Crain:

  - Parse the source .java files for class names (including inner class
    names) to figure out the target .class files that will be created.

  - Make Java support work with Repositories and SConscriptChdir(0).

  - Pass Nodes, not strings, to Builder emitter functions.

  - Refactor command-line interpolation and signature calculation
    so we can use real Node attributes.

  From Steven Knight:

  - Add Java support (javac, javah, jar and rmic).

  - Propagate the external SYSTEMROOT environment variable into ENV on
    Win32 systems, so external commands that use sockets will work.

  - Add a .posix attribute to PathList expansions.

  - Check out CVS source files using POSIX path names (forward slashes
    as separators) even on Win32.

  - Add Node.clear() and Node.FS.Entry.clear() methods to wipe out a
    Node's state, allowing it to be re-evaluated by continuous
    integration build interfaces.

  - Change the name of the Set{Build,Content}SignatureType() functions
    to {Target,Source}Signatures().  Deprecate the old names but support
    them for backwards compatibility.

  - Add internal SCons.Node.FS.{Dir,File}.Entry() methods.

  - Interpolate the null string if an out-of-range subscript is used
    for a construction variable.

  - Fix the internal Link function so that it properly links or copies
    files in subsidiary BuildDir directories.

  - Refactor the internal representation of a single execution instance
    of an action to eliminate redundant signature calculations.

  - Eliminate redundant signature calculations for Nodes.

  - Optimize out calling hasattr() before accessing attributes.

  - Say "Cleaning targets" (not "Building...") when the -c option is
    used.

  From Damyan Pepper:

  - Quote the "Entering directory" message like Make.

  From Stefan Reichor:

  - Add support for using Ghostscript to convert Postscript to PDF files.

  From Anthony Roach:

  - Add a standalone "Alias" function (separate from an Environment).

  - Make Export() work for local variables.

  - Support passing a dictionary to Export().

  - Support Import('*') to import everything that's been Export()ed.

  - Fix an undefined exitvalmap on Win32 systems.

  - Support new SetOption() and GetOption() functions for setting
    various command-line options from with an SConscript file.

  - Deprecate the old SetJobs() and GetJobs() functions in favor of
    using the new generic {Set,Get}Option() functions.

  - Fix a number of tests that searched for a Fortran compiler using the
    external PATH instead of what SCons would use.

  - Fix the interaction of SideEffect() and BuildDir() so that (for
    example) PDB files get put correctly in a BuildDir().

  From David Snopek:

  - Contribute the "Autoscons" code for Autoconf-like checking for
    the existence of libraries, header files and the like.

  - Have the Tool() function add the tool name to the $TOOLS
    construction variable.

  From Greg Spencer:

  - Support the C preprocessor #import statement.

  - Allow the SharedLibrary() Builder on Win32 systems to be able to
    register a newly-built dll using regsvr32.

  - Add a Builder for Windows type library (.tlb) files from IDL files.

  - Add an IDL scanner.

  - Refactor the Fortran, C and IDL scanners to share common logic.

  - Add .srcpath and .srcdir attributes to $TARGET and $SOURCE.

  From Christoph Wiedemann:

  - Integrate David Snopek's "Autoscons" code as the new SConf
    configuration subsystem, including caching of values between
    runs (using normal SCons dependency mechanisms), tests, and
    documentation.



RELEASE 0.13 - Mon, 31 Mar 2003 20:22:00 -0600

  From Charles Crain:

  - Fix a bug when BuildDir(duplicate=0) is used and SConscript
    files are called from within other SConscript files.

  - Support (older) versions of Perforce which don't set the Windows
    registry.



RELEASE 0.12 - Thu, 27 Mar 2003 23:52:09 -0600

  From Charles Crain:

  - Added support for the Perforce source code management system.

  - Fix str(Node.FS) so that it returns a path relative to the calling
    SConscript file's directory, not the top-level directory.

  - Added support for a separate src_dir argument to SConscript()
    that allows explicit specification of where the source files
    for an SConscript file can be found.

  - Support more easily re-usable flavors of command generators by
    calling callable variables when strings are expanded.

  From Steven Knight:

  - Added an INSTALL construction variable that can be set to a function
    to control how the Install() and InstallAs() Builders install files.
    The default INSTALL function now copies, not links, files.

  - Remove deprecated features:  the "name" argument to Builder objects,
    and the Environment.Update() method.

  - Add an Environment.SourceCode() method to support fetching files
    from source code systems.  Add factory methods that create Builders
    to support BitKeeper, CVS, RCS, and SCCS.  Add support for fetching
    files from RCS or SCCS transparently (like GNU Make).

  - Make the internal to_String() function more efficient.

  - Make the error message the same as other build errors when there's a
    problem unlinking a target file in preparation for it being built.

  - Make TARGET, TARGETS, SOURCE and SOURCES reserved variable names and
    warn if the user tries to set them in a construction environment.

  - Add support for Tar and Zip files.

  - Better documentation of the different ways to export variables to a
    subsidiary SConscript file.  Fix documentation bugs in a tools
    example, places that still assumed SCons split strings on white
    space, and typos.

  - Support fetching arbitrary files from the TARGETS or SOURCES lists
    (e.g. ${SOURCES[2]}) when calculating the build signature of a
    command.

  - Don't silently swallow exceptions thrown by Scanners (or other
    exceptions while finding a node's dependent children).

  - Push files to CacheDir() before calling the superclass built()
    method (which may clear the build signature as part of clearing
    cached implicit dependencies, if the file has a source scanner).
    (Bug reported by Jeff Petkau.)

  - Raise an internal error if we attempt to push a file to CacheDir()
    with a build signature of None.

  - Add an explicit Exit() function for terminating early.

  - Change the documentation to correctly describe that the -f option
    doesn't change to the directory in which the specified file lives.

  - Support changing directories locally with SConscript directory
    path names relative to any SConstruct file specified with -f.
    This allows you to build in another directory by simply changing
    there and pointing at the SConstruct file in another directory.

  - Change the default SConscriptChdir() behavior to change to the
    SConscript directory while it's being read.

  - Fix an exception thrown when the -U option was used with no
    Default() target specified.

  - Fix -u so that it builds things in corresponding build directories
    when used in a source directory.

  From Lachlan O'Dea:

  - Add SharedObject() support to the masm tool.

  - Fix WhereIs() to return normalized paths.

  From Jeff Petkau:

  - Don't copy a built file to a CacheDir() if it's already there.

  - Avoid partial copies of built files in a CacheDir() by copying
    to a temporary file and renaming.

  From Anthony Roach:

  - Fix incorrect dependency-cycle errors when an Aliased source doesn't
    exist.



RELEASE 0.11 - Tue, 11 Feb 2003 05:24:33 -0600

  From Chad Austin:

  - Add support for IRIX and the SGI MIPSPro tool chain.

  - Support using the MSVC tool chain when running Cygwin Python.

  From Michael Cook:

  - Avoid losing signal bits in the exit status from a command,
    helping terminate builds on interrupt (CTRL+C).

  From Charles Crain:

  - Added new AddPreAction() and AddPostAction() functions that support
    taking additional actions before or after building specific targets.

  - Add support for the PharLap ETS tool chain.

  From Steven Knight:

  - Allow Python function Actions to specify a list of construction
    variables that should be included in the Action's signature.

  - Allow libraries in the LIBS variable to explicitly include the prefix
    and suffix, even when using the GNU linker.
    (Bug reported by Neal Becker.)

  - Use DOS-standard CR-LF line endings in the scons.bat file.
    (Bug reported by Gary Ruben.)

  - Doc changes:  Eliminate description of deprecated "name" keyword
    argument from Builder definition (reported by Gary Ruben).

  - Support using env.Append() on BUILDERS (and other dictionaries).
    (Bug reported by Bj=F6rn Bylander.)

  - Setting the BUILDERS construction variable now properly clears
    the previous Builder attributes from the construction Environment.
    (Bug reported by Bj=F6rn Bylander.)

  - Fix adding a prefix to a file when the target isn't specified.
    (Bug reported by Esa Ilari Vuokko.)

  - Clean up error messages from problems duplicating into read-only
    BuildDir directories or into read-only files.

  - Add a CommandAction.strfunction() method, and add an "env" argument
    to the FunctionAction.strfunction() method, so that all Action
    objects have strfunction() methods, and the functions for building
    and returning a string both take the same arguments.

  - Add support for new CacheDir() functionality to share derived files
    between builds, with related options --cache-disable, --cache-force,
    and --cache-show.

  - Change the default behavior when no targets are specified to build
    everything in the current directory and below (like Make).  This
    can be disabled by specifying Default(None) in an SConscript.

  - Revamp SCons installation to fix a case-sensitive installation
    on Win32 systems, and to add SCons-specific --standard-lib,
    --standalone-lib, and --version-lib options for easier user
    control of where the libraries get installed.

  - Fix the ability to directly import and use Platform and Tool modules
    that have been implicitly imported into an Environment().

  - Add support for allowing an embedding interface to annotate a node
    when it's created.

  - Extend the SConscript() function to accept build_dir and duplicate
    keyword arguments that function like a BuildDir() call.

  From Steve Leblanc:

  - Fix the output of -c -n when directories are involved, so it
    matches -c.

  From Anthony Roach:

  - Use a different shared object suffix (.os) when using gcc so shared
    and static objects can exist side-by-side in the same directory.

  - Allow the same object files on Win32 to be linked into either
    shared or static libraries.

  - Cache implicit cache values when using --implicit-cache.



RELEASE 0.10 - Thu, 16 Jan 2003 04:11:46 -0600

  From Derrick 'dman' Hudson:

  - Support Repositories on other file systems by symlinking or
    copying files when hard linking won't work.

  From Steven Knight:

  - Remove Python bytecode (*.pyc) files from the scons-local packages.

  - Have FunctionActions print a description of what they're doing
    (a representation of the Python call).

  - Fix the Install() method so that, like other actions, it prints
    what would have happened when the -n option is used.

  - Don't create duplicate source files in a BuildDir when the -n
    option is used.

  - Refactor the Scanner interface to eliminate unnecessary Scanner
    calls and make it easier to write efficient scanners.

  - Added a "recursive" flag to Scanner creation that specifies the
    Scanner should be invoked recursively on dependency files returned
    by the scanner.

  - Significant performance improvement from using a more efficient
    check, throughout the code, for whether a Node has a Builder.

  - Fix specifying only the source file to MultiStepBuilders such as
    the Program Builder.  (Bug reported by Dean Bair.)

  - Fix an exception when building from a file with the same basename as
    the subdirectory in which it lives.  (Bug reported by Gerard Patel.)

  - Fix automatic deduction of a target file name when there are
    multiple source files specified; the target is now deduced from just
    the first source file in the list.

  - Documentation fixes: better initial explanation of SConscript files;
    fix a misformatted "table" in the StaticObject explanation.

  From Steven Knight and Steve Leblanc:

  - Fix the -c option so it will remove symlinks.

  From Steve Leblanc:

  - Add a Clean() method to support removing user-specified targets
    when using the -c option.

  - Add a development script for running SCons through PyChecker.

  - Clean up things found by PyChecker (mostly unnecessary imports).

  - Add a script to use HappyDoc to create HTML class documentation.

  From Lachlan O'Dea:

  - Make the Environment.get() method return None by default.

  From Anthony Roach:

  - Add SetJobs() and GetJobs() methods to allow configuration of the
    number of default jobs (still overridden by -j).

  - Convert the .sconsign file format from ASCII to a pickled Python
    data structure.

  - Error message cleanups:  Made consistent the format of error
    messages (now all start with "scons: ***") and warning messages (now
    all start with "scons: warning:").  Caught more cases with the "Do
    not know how to build" error message.

  - Added support for the MinGW tool chain.

  - Added a --debug=includes option.



RELEASE 0.09 - Thu,  5 Dec 2002 04:48:25 -0600

  From Chad Austin:

  - Add a Prepend() method to Environments, to append values to
    the beginning of construction variables.

  From Matt Balvin:

  - Add long command-line support to the "lib" Tool (Microsoft library
    archiver), too.

  From Charles Crain:

  - Allow $$ in a string to be passed through as $.

  - Support file names with odd characters in them.

  - Add support for construction variable substition on scanner
    directories (in CPPPATH, F77PATH, LIBPATH, etc.).

  From Charles Crain and Steven Knight:

  - Add Repository() functionality, including the -Y option.

  From Steven Knight:

  - Fix auto-deduction of target names so that deduced targets end
    up in the same subdirectory as the source.

  - Don't remove source files specified on the command line!

  - Suport the Intel Fortran Compiler (ifl.exe).

  - Supply an error message if there are no command-line or
    Default() targets specified.

  - Fix the ASPPCOM values for the GNU assembler.
    (Bug reported by Brett Polivka.)

  - Fix an exception thrown when a Default() directory was specified
    when using the -U option.

  - Issue a warning when -c can't remove a target.

  - Eliminate unnecessary Scanner calls by checking for the
    existence of a file before scanning it.  (This adds a generic
    hook to check an arbitrary condition before scanning.)

  - Add explicit messages to tell when we're "Reading SConscript files
    ...," "done reading SConscript files," "Building targets," and
    "done building targets."  Add a -Q option to supress these.

  - Add separate $SHOBJPREFIX and $SHOBJSUFFIX construction variables
    (by default, the same as $OBJPREFIX and $OBJSUFFIX).

  - Add Make-like error messages when asked to build a source file,
    and before trying to build a file that doesn't have all its source
    files (including when an invalid drive letter is used on WIN32).

  - Add an scons-local-{version} package (in both .tar.gz and .zip
    flavors) to help people who want to ship SCons as a stand-alone
    build tool in their software packages.

  - Prevent SCons from unlinking files in certain situations when
    the -n option is used.

  - Change the name of Tool/lib.py to Tool/mslib.py.

  From Steven Knight and Anthony Roach:

  - Man page:  document the fact that Builder calls return Node objects.

  From Steve LeBlanc:

  - Refactor option processing to use our own version of Greg Ward's
    Optik module, modified to run under Python 1.5.2.

  - Add a ParseConfig() command to modify an environment based on
    parsing output from a *-config command.

  From Jeff Petkau:

  - Fix interpretation of '#/../foo' on Win32 systems.

  From Anthony Roach:

  - Fixed use of command lines with spaces in their arguments,
    and use of Nodes with spaces in their string representation.

  - Make access and modification times of files in a BuildDir match
    the source file, even when hard linking isn't available.

  - Make -U be case insensitive on Win32 systems.

  - Issue a warning and continue when finding a corrupt .sconsign file.

  - Fix using an alias as a dependency of a target so that if one of the
    alias' dependencies gets rebuilt, the resulting target will, too.

  - Fix differently ordered targets causing unnecessary rebuilds
    on case insensitive systems.

  - Use os.system() to execute external commands whenever the "env"
    utility is available, which is much faster than fork()/exec(),
    and fixes the -j option on several platforms.

  - Fix use of -j with multiple targets.

  - Add an Options() object for friendlier accomodation of command-
    line arguments.

  - Add support for Microsoft VC++ precompiled header (.pch) files,
    debugger (.pdb) files, and resource (.rc) files.

  - Don't compute the $_CPPINCFLAGS, $_F77INCFLAGS, $_LIBFLAGS and
    $_LIBDIRFLAGS variables each time a command is executed, define
    them so they're computed only as needed.  Add a new _concat
    function to the Environment that allows people to define their
    own similar variables.

  - Fix dependency scans when $LIBS is overridden.

  - Add EnsurePythonVersion() and EnsureSConsVersion() functions.

  - Fix the overly-verbose stack trace on ListBuilder build errors.

  - Add a SetContentSignatureType() function, allowing use of file
    timestamps instead of MD5 signatures.

  - Make -U and Default('source') fail gracefully.

  - Allow the File() and Dir() methods to take a path-name string as
    the starting directory, in addition to a Dir object.

  - Allow the command handler to be selected via the SPAWN, SHELL
    and ESCAPE construction variables.

  - Allow construction variables to be overridden when a Builder
    is called.

  From sam th:

  - Dynamically check for the existence of utilities with which to
    initialize Environments by default.



RELEASE 0.08 - Mon, 15 Jul 2002 12:08:51 -0500

  From Charles Crain:

  - Fixed a bug with relative CPPPATH dirs when using BuildDir().
    (Bug reported by Bob Summerwill.)

  - Added a warnings framework and a --warn option to enable or
    disable warnings.

  - Make the C scanner warn users if files referenced by #include
    directives cannot be found and --warn=dependency is specified.

  - The BUILDERS construction variable should now be a dictionary
    that maps builder names to actions.  Existing uses of lists,
    and the Builder name= keyword argument, generate warnings
    about use of deprecated features.

  - Removed the "shared" keyword argument from the Object and
    Library builders.

  - Added separated StaticObject, SharedObject, StaticLibrary and
    SharedLibrary builders.  Made Object and Library synonyms for
    StaticObject and StaticLibrary, respectively.

  - Add LIBS and LIBPATH dependencies for shared libraries.

  - Removed support for the prefix, suffix and src_suffix arguments
    to Builder() to be callable functions.

  - Fix handling file names with multiple dots.

  - Allow a build directory to be outside of the SConstruct tree.

  - Add a FindFile() function that searches for a file node with a
    specified name.

  - Add $CPPFLAGS to the shared-object command lines for g++ and gcc.

  From Charles Crain and Steven Knight:

  - Add a "tools=" keyword argument to Environment instantiation,
    and a separate Tools() method, for more flexible specification
    of tool-specific environment changes.

  From Steven Knight:

  - Add a "platform=" keyword argument to Environment instantiation,
    and a separate Platform() method, for more flexible specification
    of platform-specific environment changes.

  - Updated README instructions and setup.py code to catch an
    installation failure from not having distutils installed.

  - Add descriptions to the -H help text for -D, -u and -U so
    people can tell them apart.

  - Remove the old feature of automatically splitting strings
    of file names on white space.

  - Add a dependency Scanner for native Fortran "include" statements,
    using a new "F77PATH" construction variable.

  - Fix C #include scanning to detect file names with characters like
    '-' in them.

  - Add more specific version / build output to the -v option.

  - Add support for the GNU as, Microsoft masm, and nasm assemblers.

  - Allow the "target" argument to a Builder call to be omitted, in
    which case the target(s) are deduced from the source file(s) and the
    Builder's specified suffix.

  - Add a tar archive builder.

  - Add preliminary support for the OS/2 Platform, including the icc
    and ilink Tools.

  From Jeff Petkau:

  - Fix --implicit-cache if the scanner returns an empty list.

  From Anthony Roach:

  - Add a "multi" keyword argument to Builder creation that specifies
    it's okay to call the builder multiple times for a target.

  - Set a "multi" on Aliases so multiple calls will append to an Alias.

  - Fix emitter functions' use of path names when using BuildDir or
    in subdirectories.

  - Fix --implicit-cache causing redundant rebuilds when the header
    file list changed.

  - Fix --implicit-cache when a file has no implicit dependencies and
    its source is generated.

  - Make the drive letters on Windows always be the same case, so that
    changes in the case of drive letters don't cause a rebuild.

  - Fall back to importing the SCons.TimeStamp module if the SCons.MD5
    module can't be imported.

  - Fix interrupt handling to guarantee that a single interrupt will
    halt SCons both when using -j and not.

  - Fix .sconsign signature storage so that output files of one build
    can be safely used as input files to another build.

  - Added a --debug=time option to print SCons execution times.

  - Print an error message if a file can't be unlinked before being
    built, rather than just silently terminating the build.

  - Add a SideEffect() method that can be used to tell the build
    engine that a given file is created as a side effect of building
    a target.  A file can be specified as a side effect of more than
    one build comand, in which case the commands will not be executed
    simultaneously.

  - Significant performance gains from not using our own version of
    the inefficient stock os.path.splitext() method, caching source
    suffix computation, code cleanup in MultiStepBuilder.__call__(),
    and replicating some logic in scons_subst().

  - Add --implicit-deps-changed and --implicit-deps-unchanged options.

  - Add a GetLaunchDir() function.

  - Add a SetBuildSignatureType() function.

  From Zed Shaw:

  - Add an Append() method to Environments, to append values to
    construction variables.

  - Change the name of Update() to Replace().  Keep Update() as a
    deprecated synonym, at least for now.

  From Terrel Shumway:

  - Use a $PYTHON construction variable, initialized to sys.executable,
    when using Python to build parts of the SCons packages.

  - Use sys.prefix, not sys.exec_prefix, to find pdb.py.



RELEASE 0.07 - Thu,  2 May 2002 13:37:16 -0500

  From Chad Austin:

  - Changes to build SCons packages on IRIX (and other *NIces).

  - Don't create a directory Node when a file already exists there,
    and vice versa.

  - Add 'dirs' and 'names' keyword arguments to SConscript for
    easier specification of subsidiary SConscript files.

  From Charles Crain:

  - Internal cleanup of environment passing to function Actions.

  - Builders can now take arbitrary keyword arguments to create
    attributes to be passed to: command generator functions,
    FunctionAction functions, Builder emitter functions (below),
    and prefix/suffix generator functions (below).

  - Command generator functions can now return ANYTHING that can be
    converted into an Action (a function, a string, a CommandGenerator
    instance, even an ActionBase instance).

  - Actions now call get_contents() with the actual target and source
    nodes used for the build.

  - A new DictCmdGenerator class replaces CompositeBuilder to support
    more flexible Builder behavior internally.

  - Builders can now take an emitter= keyword argument.  An emitter
    is a function that takes target, source, and env argument, then
    return a 2-tuple of (new sources, new targets).  The emitter is
    called when the Builder is __call__'ed, allowing a user to modify
    source and target lists.

  - The prefix, suffix and src_suffix Builder arguments now take a
    callable as well a string.  The callable is passed the Environment
    and any extra Builder keyword arguments and is expected to return
    the appropriate prefix or suffix.

  - CommandActions can now be a string, a list of command + argument
    strings, or a list of commands (strings or lists).

  - Added shared library support.  The Object and Library Builders now
    take a "shared=1" keyword argument to specify that a shared object
    or shared library should be built.  It is an error to try to build
    static objects into a shared library or vice versa.

  - Win32 support for .def files has been added.  Added the Win32-specific
    construction variables $WIN32DEFPREFIX, $WIN32DEFSUFFIX,
    $WIN32DLLPREFIX and $WIN32IMPLIBPREFIX.  When building a .dll,
    the new construction variable $WIN32_INSERT_DEF, controls whether
    the appropriately-named .def file is inserted into the target
    list (if not already present).  A .lib file is always added to
    a Library build if not present in the list of targets.

  - ListBuilder now passes all targets to the action, not just the first.

  - Fix so that -c now deletes generated yacc .h files.

  - Builder actions and emitter functions can now be initialized, through
    construction variables, to things other than strings.

  - Make top-relative '#/dir' lookups work like '#dir'.

  - Fix for relative CPPPATH directories in subsidiary SConscript files
    (broken in 0.06).

  - Add a for_signature argument to command generators, so that
    generators that need to can return distinct values for the
    command signature and for executing the command.

  From Alex Jacques:

  - Create a better scons.bat file from a py2bat.py script on the Python
    mailing list two years ago (modeled after pl2bat.pl).

  From Steven Knight:

  - Fix so that -c -n does *not* remove the targets!

  - Man page:  Add a hierarchical libraries + Program example.

  - Support long MSVC linker command lines through a builder action
    that writes to a temporary file and uses the magic MSVC "link @file"
    argument syntax if the line is longer than 2K characters.

  - Fix F77 command-line options on Win32 (use /Fo instead of -o).

  - Use the same action to build from .c (lower case) and .C (upper
    case) files on case-insensitive systems like Win32.

  - Support building a PDF file directly from a TeX or LaTeX file
    using pdftex or pdflatex.

  - Add a -x option to runtest.py to specify the script being tested.
    A -X option indicates it's an executable, not a script to feed
    to the Python interpreter.

  - Add a Split() function (identical to SCons.Util.argmunge()) for use
    in the next release, when Builders will no longer automatically split
    strings on white space.

  From Steve Leblanc:

  - Add the SConscriptChdir() method.

  From Anthony Roach:

  - Fix --debug=tree when used with directory targets.

  - Significant internal restructuring of Scanners and Taskmaster.

  - Added new --debug=dtree option.

  - Fixes for --profile option.

  - Performance improvement in construction variable substitution.

  - Implemented caching of content signatures, plus added --max-drift
    option to control caching.

  - Implemented caching of dependency signatures, enabled by new
    --implicit-cache option.

  - Added abspath construction variable modifier.

  - Added $SOURCE variable as a synonym for $SOURCES[0].

  - Write out .sconsign files on error or interrupt so intermediate
    build results are saved.

  - Change the -U option to -D.  Make a new -U that builds just the
    targets from the local SConscript file.

  - Fixed use of sys.path so Python modules can be imported from
    the SConscript directory.

  - Fix for using Aliases with the -u, -U and -D options.

  - Fix so that Nodes can be passed to SConscript files.

  From Moshe Zadka:

  - Changes for official Debian packaging.



RELEASE 0.06 - Thu, 28 Mar 2002 01:24:29 -0600

  From Charles Crain:

  - Fix command generators to expand construction variables.

  - Make FunctionAction arguments be Nodes, not strings.

  From Stephen Kennedy:

  - Performance:  Use a dictionary, not a list, for a Node's parents.

  From Steven Knight:

  - Add .zip files to the packages we build.

  - Man page:  document LIBS, fix a typo, document ARGUMENTS.

  - Added RANLIB and RANLIBFLAGS construction variables.  Only use them
    in ARCOM if there's a "ranlib" program on the system.

  - Add a configurable CFILESUFFIX for the Builder of .l and .y files
    into C files.

  - Add a CXXFile Builder that turns .ll and .yy files into .cc files
    (configurable via a CXXFILESUFFIX construction variable).

  - Use the POSIX-standard lex -t flag, not the GNU-specific -o flag.
    (Bug reported by Russell Christensen.)

  - Fixed an exception when CPPPATH or LIBPATH is a null string.
    (Bug reported by Richard Kiss.)

  - Add a --profile=FILE option to make profiling SCons easier.

  - Modify the new DVI builder to create .dvi files from LaTeX (.ltx
    and .latex) files.

  - Add support for Aliases (phony targets).

  - Add a WhereIs() method for searching for path names to executables.

  - Add PDF and PostScript document builders.

  - Add support for compiling Fortran programs from a variety of
    suffixes (a la GNU Make):  .f, .F, .for, .FOR, .fpp and .FPP

  - Support a CPPFLAGS variable on all default commands that use the
    C preprocessor.

  From Steve Leblanc:

  - Add support for the -U option.

  - Allow CPPPATH, LIBPATH and LIBS to be specified as white-space
    separated strings.

  - Add a document builder to create .dvi files from TeX (.tex) files.

  From Anthony Roach:

  - Fix:  Construction variables with values of 0 were incorrectly
    interpolated as ''.

  - Support env['VAR'] to fetch construction variable values.

  - Man page:  document Precious().



RELEASE 0.05 - Thu, 21 Feb 2002 16:50:03 -0600

  From Chad Austin:

  - Set PROGSUFFIX to .exe under Cygwin.

  From Charles Crain:

  - Allow a library to specified as a command-line source file, not just
    in the LIBS construction variable.

  - Compensate for a bug in os.path.normpath() that returns '' for './'
    on WIN32.

  - More performance optimizations:  cache #include lines from files,
    eliminate unnecessary calls.

  - If a prefix or suffix contains white space, treat the resulting
    concatenation as separate arguments.

  - Fix irregularities in the way we fetch DevStudio information from
    the Windows registry, and in our registry error handling.

  From Steven Knight:

  - Flush stdout after print so it intermixes correctly with stderr
    when redirected.

  - Allow Scanners to return a list of strings, and document how to
    write your own Scanners.

  - Look up implicit (scanned) dependencies relative to the directory
    of file being scanned.

  - Make writing .sconsign files more robust by first trying to write
    to a temp file that gets renamed.

  - Create all of the directories for a list of targets before trying
    to build any of the targets.

  - WIN32 portability fixes in tests.

  - Allow the list of variables exported to an SConscript file to be
    a UserList, too.

  - Document the overlooked LIBPATH construction variable.
    (Bug reported by Eicke Godehardt.)

  - Fix so that Ignore() ignores indirect, implicit dependencies
    (included files), not just direct dependencies.

  - Put the man page in the Debian distribution.

  - Run HTML docs through tidy to clean up the HTML (for Konqueror).

  - Add preliminary support for Unicode strings.

  - Efficiency:  don't scan dependencies more than once during the
    walk of a tree.

  - Fix the -c option so it doesn't stop removing targets if one doesn't
    already exist.
    (Bug reported by Paul Connell.)

  - Fix the --debug=pdb option when run on Windows NT.
    (Bug reported by Paul Connell.)

  - Add support for the -q option.

  From Steve Leblanc:

  - Add support for the -u option.

  - Add .cc and .hh file suffixes to the C Scanner.

  From Anthony Roach:

  - Make the scons script return an error code on failures.

  - Add support for using code to generate a command to build a target.



RELEASE 0.04 - Wed, 30 Jan 2002 11:09:42 -0600

  From Charles Crain:

  - Significant performance improvements in the Node.FS and
    Scanner subsystems.

  - Fix signatures of binary files on Win32 systems.

  - Allow LIBS and LIBPATH to be strings, not just arrays.

  - Print a traceback if a Python-function builder throws an exception.

  From Steven Knight:

  - Fix using a directory as a Default(), and allow Default() to
    support white space in file names for strings in arrays.

  - Man page updates:  corrected some mistakes, documented various
    missing Environment methods, alphabetized the construction
    variables and other functions, defined begin and end macros for
    the example sections, regularized white space separation, fixed
    the use of Export() in the Multiple Variants example.

  - Function action fixes:  None is now a successful return value.
    Exceptions are now reported.  Document function actions.

  - Add 'Action' and 'Scanner' to the global keywords so SConscript
    files can use them too.

  - Removed the Wrapper class between Nodes and Walkers.

  - Add examples using Library, LIBS, and LIBPATH.

  - The C Scanner now always returns a sorted list of dependencies
    so order changes don't cause unnecessary rebuilds.

  - Strip $(-$) bracketed text from command lines.  Use this to
    surround $_INCDIRS and $_LIBDIRS so we don't rebuild in response
    to changes to -I or -L options.

  - Add the Ignore() method to ignore dependencies.

  - Provide an error message when a nonexistent target is specified
    on the command line.

  - Remove targets before building them, and add an Environment
    Precious() method to override that.

  - Eliminate redundant calls to the same builder when the target is a
    list of targets:  Add a ListBuilder class that wraps Builders to
    handle lists atomically.  Extend the Task class to support building
    and updating multiple targets in a single Task.  Simplify the
    interface between Task and Taskmaster.

  - Add a --debug=pdb option to re-run SCons under the Python debugger.

  - Only compute a build signature once for each node.

  - Changes to our sys.path[] manipulation to support installation into
    an arbitrary --prefix value.

  From Steve Leblanc:

  - Add var=value command-line arguments.



RELEASE 0.03 - Fri, 11 Jan 2002 01:09:30 -0600

  From Charles Crain:

  - Performance improvements in the Node.FS and Sig.Calculator classes.

  - Add the InstallAs() method.

  - Execute commands through an external interpreter (sh, cmd.exe, or
    command.com) to handle redirection metacharacters.

  - Allow the user to supply a command handler.

  From Steven Knight:

  - Search both /usr/lib and /usr/local/lib for scons directories by
    adding them both to sys.path, with whichever is in sys.prefix first.

  - Fix interpreting strings of multiple white-space separated file names
    as separate file names, allowing prefixes and suffixes to be appended
    to each individually.

  - Refactor to move CompositeBuilder initialization logic from the
    factory wrapper to the __init__() method, and allow a Builder to
    have both an action and a src_builder (or array of them).

  - Refactor BuilderBase.__call__() to separate Node creation/lookup
    from initialization of the Node's builder information.

  - Add a CFile Builder object that supports turning lex (.l) and
    yacc (.y) files into .c files.

  - Document: variable interpretation attributes; how to propogate
    the user's environment variables to executed commands; how to
    build variants in multiple BuildDirs.

  - Collect String, Dict, and List type-checking in common utility
    routines so we can accept User{String,Dict,List}s all over.

  - Put the Action factory and classes into their own module.

  - Use one CPlusPlusAction in the Object Builder's action dictionary,
    instead of letting it create multiple identical instances.

  - Document the Install() and InstallAs() methods.

  From Steve Leblanc:

  - Require that a Builder be given a name argument, supplying a
    useful error message when it isn't.

  From Anthony Roach:

  - Add a "duplicate" keyword argument to BuildDir() that can be set
    to prevent linking/copying source files into build directories.

  - Add a "--debug=tree" option to print an ASCII dependency tree.

  - Fetch the location of the Microsoft Visual C++ compiler(s) from
    the Registry, instead of hard-coding the location.

  - Made Scanner objects take Nodes, not path names.

  - Have the C Scanner cache the #include file names instead of
    (re-)scanning the file each time it's called.

  - Created a separate class for parent "nodes" of file system roots,
    eliminating the need for separate is-parent-null checks everywhere.

  - Removed defined __hash__() and __cmp() methods from FS.Entry, in
    favor of Python's more efficient built-in identity comparisons.



RELEASE 0.02 - Sun, 23 Dec 2001 19:05:09 -0600

  From Charles Crain:

  - Added the Install(), BuildDir(), and Export() methods.

  - Fix the -C option by delaying setting the top of the FS tree.

  - Avoid putting the directory path on the libraries in the LIBS
    construction variable.

  - Added a GetBuildPath() method to return the full path to the
    Node for a specified string.

  - Fixed variable substitution in CPPPATH and LIBPATH.

  From Steven Knight:

  - Fixed the version comment in the scons.bat (the UNIX geek used
    # instead of @rem).

  - Fix to setup.py so it doesn't require a sys.argv[1] argument.

  - Provide make-like warning message for "command not found" and
    similar errors.

  - Added an EXAMPLES section to the man page.

  - Make Default() targets properly relative to their SConscript
    file's subdirectory.

  From Anthony Roach:

  - Documented CXXFLAGS, CXXCOM, and CPPPATH.

  - Fixed SCONS_LIB_DIR to work as documented.

  - Made Default() accept Nodes as arguments.

  - Changed Export() to make it easier to use.

  - Added the Import() and Return() methods.



RELEASE 0.01 - Thu Dec 13 19:25:23 CST 2001

A brief overview of important functionality available in release 0.01:

  - C and C++ compilation on POSIX and Windows NT.

  - Automatic scanning of C/C++ source files for #include dependencies.

  - Support for building libraries; setting construction variables
    allows creation of shared libraries.

  - Library and C preprocessor search paths.

  - File changes detected using MD5 signatures.

  - User-definable Builder objects for building files.

  - User-definable Scanner objects for scanning for dependencies.

  - Parallel build (-j) support.

  - Dependency cycles detected.

  - Linux packages available in RPM and Debian format.

  - Windows installer available.