1 GNU Autoconf NEWS - User visible changes.
3 * Noteworthy changes in release ?.? (????-??-??) [?]
5 ** Backward incompatibilities
7 *** AC_PROG_CC now prefers C23 if available.
8 Older code may need to be updated, as C23 has removed old-style
9 (K&R) function definitions and declarations, and has new keywords
10 alignas, alignof, bool, constexpr, false, nullptr, static_assert,
11 thread_local, typeof, typeof_unqual, true.
13 *** AC_PROG_CC no longer checks __STDC__ or variable length arrays (VLAs).
14 This ports better to MSVC, which does not define __STDC__ and does
15 not support VLAs. Although C99 requires VLAs, they are optional in
16 C11 and later. Programs can use AC_C_VARARRAYS and __STDC_NO_VLA__
17 to use VLAs if available.
19 * Noteworthy changes in release 2.72 (2023-12-22) [release]
21 ** Backward incompatibilities
23 *** Configure scripts no longer support pre-1989 C compilers.
24 Specifically, compilers that *only* implement the original “K&R”
25 function definition syntax, and not the newer “prototyped” syntax,
26 will not be able to parse the test programs now emitted by
27 AC_CHECK_FUNC, AC_LANG_CALL, and similar macros. AC_PROG_CC still
28 accepts such compilers, but this may change in the near future.
30 This change was necessary in order to support the upcoming 2024
31 edition of the C standard (often referred to as “C23”), which will
32 officially remove the function declaration syntax used by
33 AC_CHECK_FUNC in Autoconf 2.71 and earlier. We feel that support
34 for compilers that support only C 2024 is more useful, nowadays,
35 than support for compilers that don’t implement a core feature of
38 *** Autoconf developers now need Perl 5.10 (2007) or later.
39 “Autoconf developers” means specifically people hacking on Autoconf
40 itself. Autoconf *users*, i.e. authors of configure.ac files and
41 add-on M4 macros, still need only Perl 5.6 (2000) or later.
43 We do recommend all Autoconf users upgrade to Perl 5.10 or later if
44 possible, as this version significantly improves Perl’s ability to
45 handle files with last-modification timestamps separated by less
46 than a second. (Note: even in the most recent release, Perl cannot
47 always match the file system’s timestamp resolution.)
49 Generated configure scripts continue to run without Perl.
51 *** Autoconf users now need GNU M4 1.4.8 (2006) or later.
52 Use of GNU M4 1.4.16 or later is recommended, as all earlier versions
53 are known to have had serious bugs in the text-processing builtins
54 on some, but not all, operating systems. Autoconf’s own configure
55 script will attempt to find a version of M4 that is not affected by
58 Note: Autoconf 2.70 and 2.71 include code that malfunctions with
59 M4 1.4.6 or 1.4.7. However, the only effect of the malfunction is
60 that you will get a confusing error message if you run autoconf on
61 a configure.ac that neglects to use AC_INIT or AC_OUTPUT.
63 Generated 'configure' scripts continue to run without M4.
65 *** Some m4sh diversions have been renumbered.
66 This will only affect macros that use m4_divert with numbered rather
67 than named diversions, which has always been strongly discouraged
68 both by the documentation and with warnings.
70 *** AC_FUNC_GETGROUPS and AC_TYPE_GETGROUPS no longer run test programs.
71 These macros were testing for OS bugs that we believe are at least
72 twenty years in the past. Most operating systems are now trusted to
73 provide an accurate prototype for getgroups in unistd.h, and to
74 implement it as specified in POSIX.
76 AC_FUNC_GETGROUPS still includes a short block-list of OSes with
77 known, severe bugs in getgroups. It can be overridden using
78 config.site. If you encounter a mistake in this list,
79 please report it to bug-autoconf.
81 *** All internal uses of AC_EGREP_CPP and AC_EGREP_HEADER have been removed.
82 These macros look for text matching a regular expression in the
83 output of the C preprocessor. Their use has been discouraged for
84 many years, as they tend to be unreliable; it is better to find a
85 way to use AC_COMPILE_IFELSE or AC_PREPROC_IFELSE instead. We have
86 finally taken our own advice.
88 This change might break configure scripts that expected probes for
89 ‘grep’ and/or the C preprocessor to happen as a side effect of an
90 unrelated operation. Such scripts can be fixed by adding
91 AC_PROG_EGREP and/or AC_PROG_CPP in an appropriate place.
93 The macros affected by this change are AC_C_STRINGIZE,
94 AC_C_VARARRAYS, AC_FUNC_GETGROUPS, AC_FUNC_GETLOADAVG,
95 AC_HEADER_TIOCGWINSZ, AC_PROG_GCC_TRADITIONAL, AC_TYPE_GETGROUPS,
96 AC_TYPE_UID_T, and AC_XENIX_DIR. Many of these macros are themselves
97 obsolete; if your configure script uses any of them, check whether
98 it is actually needed.
102 *** Support for ensuring time_t is Y2038-safe
103 configure can now ensure that time_t can represent moments in time
104 after 18 January 2038, i.e. 2**31 - 1 seconds after the Unix epoch.
105 On most “64-bit” systems this is true by default; the new feature
106 is detection of systems where time_t is a 32-bit signed integer by
107 default, *and* there is an alternative mode in which it is larger,
108 in which case that mode will be enabled.
110 In this release, all configure scripts that use AC_SYS_LARGEFILE
111 gain a new command line option --enable-year2038. When this option
112 is used, the configure script will check for and enable support for
115 This release also adds two new macros, AC_SYS_YEAR2038 and
116 AC_SYS_YEAR2038_RECOMMENDED. Both have all the effects of
117 AC_SYS_LARGEFILE. (This is because it is not possible to enlarge
118 time_t without also enlarging off_t, on any system we are aware of.)
120 AC_SYS_YEAR2038 additionally flips the default for --enable-year2038;
121 a configure script that uses this macro will check for and enable
122 support for a large time_t by default, but this can be turned off by
123 using --disable-year2038. AC_SYS_YEAR2038_RECOMMENDED goes even
124 further, and makes the configure script fail on systems that do not
125 seem to support timestamps after 18 January 2038 at all. This
126 failure can be suppressed by using --disable-year2038.
128 Changing the size of time_t can change a library’s ABI. Therefore,
129 application and library builders should take care that all packages
130 are configured with consistent use of --enable-year2038 or
131 --disable-year2038, to ensure binary compatibility. This is similar
132 to longstanding consistency requirements with --enable-largefile and
135 In this release, these macros only know how to enlarge time_t on two
136 classes of systems: 32-bit MinGW, and any system where time_t can be
137 enlarged by defining the preprocessor macro _TIME_BITS with the
138 value 64. At the time this NEWS entry was written, only GNU libc
139 (version 2.34 and later) supported the latter macro. Authors of
140 other C libraries with a 32-bit time_t are encouraged to adopt
141 _TIME_BITS, rather than inventing a different way to enlarge time_t.
143 *** AC_USE_SYSTEM_EXTENSIONS now enables C23 Annex F extensions
144 by defining __STDC_WANT_IEC_60559_EXT__.
146 ** Obsolete features and new warnings
148 *** Autoconf now quotes 'like this' instead of `like this'.
149 Autoconf’s diagnostics now follow current GNU coding standards,
150 which say that diagnostics in the C locale should quote 'like this'
151 with plain apostrophes instead of the older GNU style `like this'
152 with grave accent and apostrophe.
154 *** AC_PROG_GCC_TRADITIONAL no longer does anything.
155 This macro has had no useful effect since GCC dropped support for
156 traditional-mode compilation in version 3.3 (released in 2003), and
157 the systems that needed it are also long obsolete. It is now a
158 compatibility synonym for AC_PROG_CC.
162 *** autom4te now uses fine-grained file timestamps
163 Autoconf’s internal “autom4te” utility is now able to compare file
164 modification timestamps with sub-second precision, when available.
165 This eliminates a class of bugs where autom4te fails to regenerate
166 an outdated file. Automake 1.17 (forthcoming) is required for a
169 *** AC_HEADER_STDBOOL, AC_CHECK_HEADER_STDBOOL are obsolescent and less picky.
170 These macros are now obsolescent, as most programs can simply include
171 stdbool.h unconditionally. If you use these macros, they now accept
172 a stdbool.h that exists but does nothing, so long as ‘bool’, ‘true’,
173 and ‘false’ work anyway. This is for compatibility with C23 and
176 *** AC_PROG_MKDIR_P now falls back on plain 'mkdir -p'.
177 When AC_PROG_MKDIR_P cannot find a mkdir implementation that is
178 known to lack race condition bugs, it now falls back on 'mkdir -p'
179 instead of falling back on a relative path to install-sh, as the
180 relative paths now seem to be a more important problem than the
181 problems of ancient mkdir implementations with race condition bugs.
182 See <https://savannah.gnu.org/support/?110740>. The only ancient
183 mkdir still supported is Solaris 10 /usr/bin/mkdir, and for that
184 platform AC_PROG_MKDIR_P falls back on /opt/sfw/bin/mkdir which
185 should work if it is installed; if not, you should avoid parallel
186 'make' on that platform.
188 *** Better diagnostics for calling m4_warn() with a bad first argument
189 Calling m4_warn with a first argument that doesn’t match any of the
190 official warning categories now produces a sensible error message,
191 instead of something that makes it look like there’s a bug in the
192 guts of autom4te. Also, the documentation has been adjusted in
193 several places to make it clearer what the official warning
196 Note: In Autoconf 2.69 and earlier, the manual said that [] and [all]
197 could be used as the first argument to m4_warn. This was incorrect,
200 *** Improved compatibility with a wide variety of systems and tools
201 including CheriBSD, Darwin (macOS), GNU Guix, OS/2, z/OS, Bash 5.2,
202 the BusyBox shell and utilities, Clang/LLVM version 16, the upcoming
207 *** AC_SYS_LARGEFILE and AC_SYS_YEAR2038 only work correctly in C mode.
209 This is only a problem for configure scripts that invoke either
210 macro while AC_LANG([something other than C]) is in effect, and
211 will only be a *visible* problem on systems where support
212 for large files and/or timestamps after 2038 are *available*
213 but not enabled by default.
215 This is the cause of the AC_SYS_LARGEFILE, AC_SYS_YEAR2038, and/or
216 AC_SYS_YEAR2038_RECOMMENDED testsuite failures on some systems.
217 See <https://savannah.gnu.org/support/index.php?110983> for details
220 * Noteworthy changes in release 2.71 (2021-01-28) [stable]
222 ** Bug fixes, including:
224 *** Compilers that support C99 but not C2011 are detected correctly.
226 *** Compatibility improved with clang and Oracle C++.
228 *** Compatibility restored with automake's rules for regenerating configure.
230 *** Compatibility restored with old versions of std-gnu11.m4.
232 Packages that wish to maintain compatibility with Autoconf 2.69 or
233 older, should update their copy of std-gnu11.m4 from Gnulib as soon
234 as practical, as the compatibility code bulks up the configure script.
236 Packages that require Autoconf 2.70 can drop this file entirely.
238 * Noteworthy changes in release 2.70 (2020-12-08) [stable]
240 ** Backward incompatibilities:
242 *** Warnings about obsolete constructs are now on by default.
244 These warnings can be turned off with ‘-Wno-obsolete’.
246 Many of these warnings advise maintainers to run autoupdate.
247 Be aware that autoupdate cannot solve all backward compatibility
248 problems, and cannot completely solve all of the problems it does
249 address. A configure script edited by autoupdate is likely to
250 need further manual fix-ups.
252 *** Many macros have become pickier about argument quotation.
254 If you get a shell syntax error from your generated configure
255 script, or seemingly impossible misbehavior (e.g. entire blocks of
256 the configure script not getting executed), check first that all
257 macro arguments are properly quoted. The “M4 Quotation” section of
258 the manual explains how to quote macro arguments properly.
260 It is unfortunately not possible for autoupdate to correct
263 *** Many macros no longer AC_REQUIRE as many other macros as they used to.
265 This can expose several classes of latent bugs. These are the ones
268 - Make sure to explicitly invoke all of the macros that set result
269 variables used later in the configure script, or in generated
272 - Autoconf macros that use AC_REQUIRE are not safe to use in shell
273 control-flow constructs that appear outside of macros defined by
274 AC_DEFUN. Use AS_IF, AS_CASE, etc. instead. (See the
275 “Prerequisite Macros” section of the manual for details.)
277 The set of macros that use AC_REQUIRE internally may change from
278 release to release. The only macros that are guaranteed *not* to
279 use AC_REQUIRE are the macros for acting on the results of a
280 test: AC_DEFINE, AC_SUBST, AC_MSG_*, AC_CACHE_CHECK, etc.
282 - AC_REQUIRE cannot be applied to macros that need to be used with
283 arguments. Instead, invoke the macro normally, with its arguments.
285 *** More macros use config.sub and config.guess internally.
287 As a consequence of improved support for cross compilation (see below),
288 more macros now use the auxiliary scripts ‘config.sub’ and ‘config.guess’.
289 If you use any of the affected macros, these scripts must be available
290 when your configure script is run, even if you have no intention of
291 ever cross-compiling your program.
293 autoreconf will issue an error if any auxiliary scripts are needed but
294 cannot be found. (It is not currently possible to make autoconf
295 itself issue this error.)
297 ‘autoreconf --install’ will add ‘config.sub’, ‘config.guess’, and
298 ‘install-sh’ to your source tree if they are needed. If you are
299 using Automake, scripts added to your tree by ‘autoreconf --install’
300 will automatically be included in the tarball produced by ‘make dist’;
301 otherwise, you will need to arrange for them to be distributed
304 See the “Input” section of the manual for more detail, including
305 where to get the auxiliary scripts that may be needed by autoconf macros.
307 *** Setting CC to a C++ compiler is no longer supported.
309 The C and C++ languages have diverged enough that we can no longer
310 guarantee that test C programs will be processed as intended by a
311 C++ compiler. In this release, configure will proceed anyway, but
312 many test results will be incorrect. In a future release, we may
313 make AC_PROG_CC error out if it detects that CC is a C++ compiler.
315 See the “Language Choice” section of the manual for instructions on
316 how to write configure scripts for C++ programs, and for programs
317 with code in more than one language.
319 *** Running configure tests with warnings promoted to errors is not supported.
321 For instance, setting ‘CC="gcc -Werror"’ on the configure command
322 line, or adding -Werror to CFLAGS early in the configure script when
323 the compiler recognizes this option, is very likely to cause
324 subsequent tests to fail.
326 This has never been guaranteed to work; the code generated by
327 AC_CHECK_FUNC, for instance, is incorrect by a strict reading of the
328 original 1989 C standard, and has been ever since that macro was
329 introduced. Problems are more likely with newer, pickier compilers.
331 To enable compiler warnings and/or warnings-as-errors mode for your
332 own code, we currently recommend a dedicated Makefile variable
333 (e.g. ‘WARN_CFLAGS’) that is set by AC_SUBST when appropriate.
334 The Gnulib ‘warnings’ and ‘manywarnings’ modules can help with this.
335 We plan to add core support for probing for useful sets of compiler
336 warnings in a future release.
338 *** Including confdefs.h manually may cause test failures.
340 This has never been necessary; confdefs.h is automatically included
341 at the beginning of all test programs (by AC_LANG_SOURCE). Because
342 of the way confdefs.h is generated and used, it is not practical to
343 give it a multiple inclusion guard. Therefore, if you include it
344 yourself, all of its definitions will be scanned twice.
346 Historically this has not been a problem, because confdefs.h only
347 makes macro definitions, and the C standard allows redefinitions
348 of macros as long as they’re exactly the same, but newer, pickier
349 compilers may complain anyway (see for instance GCC bug 97998).
351 *** Older versions of automake and aclocal (< 1.8) are no longer supported.
353 *** AC_CONFIG_SUBDIRS no longer directly supports Cygnus configure.
355 If you are still using an Autoconf script to drive configuration of
356 a multi-package build tree where some subdirectories use Cygnus
357 configure, copy or link $ac_aux_dir/configure into each subdirectory
358 where it is needed. Please also contact us; we were under the
359 impression nobody used this very old tool anymore.
361 *** AC_CHECK_HEADER and AC_CHECK_HEADERS only do a compilation test.
363 This completes the transition from preprocessor-based header tests
364 begun in Autoconf 2.56.
366 The double test that was the default since Autoconf 2.64 is no
367 longer available. You can still request a preprocessor-only test
368 by specifying [-] as the fourth argument to either macro, but this
369 is now deprecated. If you really need that behavior use
372 *** AC_INCLUDES_DEFAULT assumes an ISO C90 compliant C implementation.
374 Specifically, it assumes that the ISO C90 header <stddef.h>
375 is available, without checking for it, and it does not include
376 the pre-standard header <memory.h> at all. If the POSIX header
377 <strings.h> exists, it will be included, without first testing
378 whether both <string.h> and <strings.h> can be included in the
381 AC_INCLUDES_DEFAULT still checks for the existence of <stdlib.h>,
382 <string.h>, and <stdio.h>, because these headers may not exist
383 in a “freestanding environment” (a compilation mode intended for OS
384 kernels and similar, where most of the features of the C library are
385 optional). Most programs need not use ‘#ifdef HAVE_STDLIB_H’ etc in
388 For compatibility’s sake, the C preprocessor macro STDC_HEADERS
389 will be defined when both <stdlib.h> and <string.h> are available;
390 however, <stdarg.h> and <float.h> are no longer checked for
391 (these, like <stddef.h>, are required to exist in a freestanding
392 environment). New code should not refer to this macro.
394 Future releases of Autoconf may reduce the set of headers checked
395 for by AC_INCLUDES_DEFAULT.
397 *** AS_ECHO and AS_ECHO_N unconditionally use ‘printf’.
399 This is substantially simpler, more reliable, and, in most cases,
400 faster than attempting to use ‘echo’ at all. However, if ‘printf’
401 is not a shell builtin, configure scripts will run noticeably
402 slower, and if ‘printf’ is not available at all, they will crash.
403 The only systems where this is known to be a problem are extremely
404 old, and unlikely to be able to handle modern C programs for other
405 reasons (e.g. not having a C90-compliant compiler at all).
407 *** Configure scripts require support for $( ... ) command substitution.
409 This POSIX shell feature is approximately the same age as
410 user-defined functions, but there do exist shells that support
411 functions and not $( ... ), such as Solaris 10 /bin/sh.
413 Configure scripts will automatically locate a shell that supports
414 this feature and re-execute themselves with it, if necessary, so
415 the new requirement should be transparent to most users.
417 In this release, most of Autoconf’s code still uses the older `...`
418 notation for command substitution.
420 *** AC_INIT now trims extra white space from its arguments.
422 For instance, AC_INIT([ GNU Hello ], [1.0]) will set PACKAGE_NAME
425 *** Macros that take whitespace-separated lists as arguments
426 now always expand macros within those arguments.
428 Formerly, these macros would *usually* expand those arguments, but
429 the behavior was not reliable nor was it consistent between autoconf
432 Macro expansion within these arguments is deprecated; if expansion
433 changes the list, a warning in the “obsolete” category will be
434 emitted. Note that ‘dnl’ is a macro. Putting ‘dnl’ comments inside
435 any argument to an Autoconf macro is, in general, only supported
436 when that argument takes more Autoconf code (e.g. the ACTION-IF-TRUE
437 argument to AC_COMPILE_IFELSE).
439 The affected macros are AC_CHECK_FILES, AC_CHECK_FUNCS,
440 AC_CHECK_FUNCS_ONCE, AC_CHECK_HEADERS, AC_CHECK_HEADERS_ONCE,
441 AC_CONFIG_MACRO_DIRS, AC_CONFIG_SUBDIRS, and AC_REPLACE_FUNCS.
443 *** AC_FUNC_VFORK no longer ignores a signal-handling bug in Solaris 2.4.
445 This bug was being ignored because Emacs wanted to use ‘vfork’ on
446 Solaris 2.4 anyway, but current versions of Emacs have dropped
447 support for Solaris 2.4. Most programs will want to avoid ‘vfork’
448 on this OS because of this bug.
450 *** AC_FUNC_STRERROR_R assumes strerror_r is unavailable if it’s not declared.
452 The fallback technique it used to probe strerror_r’s return type
453 when the function was present in the C library, but not declared by
454 <string.h>, was fragile and did not work at all when cross-compiling.
455 The systems where this fallback was necessary were all obsolete.
457 Programs that use AC_FUNC_STRERROR_R should make sure to test the
458 preprocessor macro HAVE_DECL_STRERROR_R before using strerror_r at all.
460 *** AC_OPENMP can’t be used if you have files named ‘mp’ or ‘penmp’.
462 Autoconf will now issue an error if AC_OPENMP is used in a configure
463 script that’s in the same directory as a file named ‘mp’ or ‘penmp’.
464 Configure scripts that use AC_OPENMP will now error out upon
465 encountering files with these names in their working directory
466 (e.g. when the build directory is separate from the source directory).
468 If you have files with these names at the top level of your source
469 tree, we recommend either renaming them or moving them into a
470 subdirectory. See the documentation of AC_OPENMP for further
475 *** Configure scripts now support a ‘--runstatedir’ option.
477 This defaults to ‘${localstatedir}/run’. It can be used, for
478 instance, to place per-process temporary runtime files (such as pid
479 files) into ‘/run’ instead of ‘/var/run’.
481 *** autoreconf will now run gtkdocize and intltoolize when appropriate.
483 *** autoreconf now recognizes AM_GNU_GETTEXT_REQUIRE_VERSION.
485 This macro can be used with gettext 0.19.6 or later to specify
486 a *minimum* version requirement for gettext, instead of the *fixed*
487 version requirement specified by AM_GNU_GETTEXT_VERSION.
489 *** autoheader handles secondary config headers better.
491 It is no longer necessary to duplicate AC_DEFINE templates in the
492 main configuration header for autoheader to notice them.
494 *** AC_PROG_CC now enables C2011 mode if the compiler supports it.
496 If not, it will fall back to C99 and C89, as before. Similarly,
497 AC_PROG_CXX now enables C++2011 if available, falling back on C++98.
499 *** New macro AC_C__GENERIC tests for C2011 _Generic support.
501 *** AC_C_VARARRAYS has been aligned with C2011.
503 It now defines __STDC_NO_VLA__ if variable-length arrays are not
504 supported but the compiler does not define __STDC_NO_VLA__.
506 For backward compatibility with Autoconf 2.61-2.69 AC_C_VARARRAYS
507 still defines HAVE_C_VARARRAYS, but this result macro is obsolescent.
509 *** New macro AC_CONFIG_MACRO_DIRS.
511 This macro can be used more than once and accepts a list of
512 directories to search for local M4 macros. With Automake 1.13 and
513 later, use of this macro eliminates a reason to use ACLOCAL_AMFLAGS
516 The older AC_CONFIG_MACRO_DIR, which could only be used once, is
517 still supported but considered deprecated.
519 *** AC_USE_SYSTEM_EXTENSIONS knows about more extensions to enable.
521 System extensions will now be enabled on HP-UX, macOS, and MINIX.
522 Optional ISO C library components (e.g. decimal floating point) will
525 *** New compatibility macro AC_CHECK_INCLUDES_DEFAULT.
527 This macro runs the checks normally performed as a side-effect by
528 AC_INCLUDES_DEFAULT, if they haven’t already been done. Autoupdate
529 will replace certain obsolete constructs, whose only remaining
530 useful effect is to trigger those checks, with this macro. It is
531 unlikely to be useful otherwise.
533 *** AC_REQUIRE_AUX_FILE has been improved.
535 Configure scripts now check, on startup, for the availability of all
536 the aux files that were mentioned in an AC_REQUIRE_AUX_FILE
537 invocation. This should help prevent certain classes of packaging
540 Also, it is no longer necessary for third-party macros that use
541 AC_REQUIRE_AUX_FILE to mention AC_CONFIG_AUX_DIR_DEFAULT. However,
542 if you are using AC_CONFIG_AUX_DIR_DEFAULT *without* also using
543 AC_REQUIRE_AUX_FILE, please start using AC_REQUIRE_AUX_FILE to
544 specify the aux files you actually need, so that the check can be
547 *** AC_PROG_LEX has an option to not look for yywrap.
549 AC_PROG_LEX now takes one argument, which may be either ‘yywrap’ or
550 ‘noyywrap’. If it is ‘noyywrap’, AC_PROG_LEX will only set LEXLIB
551 to ‘-lfl’ or ‘-ll’ if a scanner that defines both main and yywrap
552 itself still needs something else from that library. On the other
553 hand, if it is ‘yywrap’, AC_PROG_LEX will fail (setting LEX to ‘:’
554 and LEXLIB to nothing) if it can’t find a library that defines yywrap.
556 In the absence of arguments, AC_PROG_LEX’s behavior is bug-compatible
557 with 2.69, which did neither of the above things (see the manual for
558 details). This mode is deprecated.
560 We encourage all programs that use AC_PROG_LEX to use the new
561 ‘noyywrap’ mode, and to define yywrap themselves, or use %noyywrap.
562 The yywrap function in lib(f)l is trivial, and self-contained
563 scanners are easier to work with.
565 ** Obsolete features and new warnings
567 *** Use of the long-deprecated name ‘configure.in’ for the autoconf
568 input file now elicits a warning in the “obsolete” category.
570 *** Use of the undocumented internal shell variables $as_echo and
571 $as_echo_n now elicits a warning in the “obsolete” category.
572 The macros AS_ECHO and AS_ECHO_N should be used instead.
574 *** autoconf will now issue warnings (in the “syntax” category)
575 if the input file is missing a call to AC_INIT and/or AC_OUTPUT.
577 *** autoconf will now issue warnings (in the “syntax” category)
578 for a non-literal URL argument to AC_INIT, and for a TARNAME
579 argument to AC_INIT which is either non-literal or contains
580 characters that should not be used in file names (e.g. ‘*’).
582 *** AC_PROG_CC_STDC, AC_PROG_CC_C89, AC_PROG_CC_C99 are now obsolete.
584 Applications should use AC_PROG_CC.
586 *** AC_HEADER_STDC and AC_HEADER_TIME are now stubs.
588 They still define the C preprocessor macros STDC_HEADERS and
589 TIME_WITH_SYS_TIME, respectively, but they no longer check for the
590 ancient, non-ISO-C90 compliant systems where formerly those macros
591 would not be defined. Autoupdate will remove them.
593 These macros were already labeled obsolete in the manual.
595 *** AC_DIAGNOSE, AC_FATAL, AC_WARNING, and _AC_COMPUTE_INT are now
596 replaced with modern equivalents by autoupdate.
598 These macros were already labeled obsolete in the manual.
600 *** AC_CONFIG_HEADER is now diagnosed as obsolete, and replaced with
601 AC_CONFIG_HEADERS by autoupdate.
603 This macro has been considered obsolete for many years and was not
606 *** The macro AC_OBSOLETE is obsolete.
608 Autoupdate will replace it with m4_warn([obsolete], [explanation]).
609 If possible, macros using AC_OBSOLETE should be converted to use
610 AU_DEFUN or AU_ALIAS instead, which enables autoupdate to replace
611 them, but this has to be done by hand and is not always possible.
613 This macro has been considered obsolete for many years, but was not
614 officially declared as such.
616 *** Man pages for config.guess and config.sub are no longer provided.
618 They were moved to the master source tree for config.guess and
623 *** Compatible with current Automake, Libtool, Perl, Texinfo, and shells.
625 All of autoconf’s tools and generated scripts, and the build process
626 and testsuite for autoconf itself, have been tested to work
627 correctly with current versions of Automake, Libtool, Perl, Texinfo,
628 bash, ksh93, zsh, and FreeBSD and NetBSD /bin/sh.
630 Generated configure scripts are expected to work reliably with an
631 even wider variety of shells, including BusyBox sh and various
632 proprietary Unixes’ /bin/sh, as long as they are minimally compliant
633 with the Unix95 shell specification. Notably, support for
634 shell-script functions and the ‘printf’ builtin are required.
636 *** Checks compatible with current language standards and compilers.
638 Many individual macros have been improved to accommodate changes in
639 recent versions of the C and C++ language standards, and new
640 features and quirks of commonly used compilers (both free and
643 *** Improved support for cross compilation.
645 Many individual macros have been improved to produce more accurate
646 results when cross-compiling.
648 *** Improved robustness against unusual build environments.
650 Many bugs have been fixed where generated configure scripts would
651 fail catastrophically under unusual conditions, such as stdout being
652 closed, or $TMPDIR not being an absolute path, or the root directory
653 being mentioned in $PATH.
655 *** AC_CHECK_FUNCS_ONCE and AC_CHECK_HEADERS_ONCE now support multiple
656 programming languages. They no longer perform all checks in the
657 language active upon the first use of the macro.
659 *** AC_CHECK_DECL and AC_CHECK_DECLS will now detect missing declarations for
660 library functions that are also Clang compiler builtins.
662 *** AC_PATH_X and AC_PATH_XTRA don’t search for X11 when cross-compiling.
664 Libraries and headers found by running xmkmf or searching /usr/X11,
665 /usr/X11R7, etc. are likely to belong to a native X11 installation
666 for the build machine and to be inappropriate for cross compilation.
668 To cross-compile programs that require X11, we recommend putting the
669 headers and libraries for the host system in your cross-compiler’s
670 default search paths. Alternatively, use configure’s --x-includes
671 and --x-libraries command line options to tell it where they are.
673 *** AS_IF’s if-false argument may be empty after macro expansion.
675 This long-standing limitation broke configure scripts that used
676 macros in this position that emitted shell code in 2.69 but no
677 longer do, so we have lifted it.
679 *** AC_HEADER_MAJOR detects the location of the major, minor, and
680 makedev macros correctly under glibc 2.25 and later.
682 *** AC_FC_LINE_LENGTH now documents the maximum portable length of
683 “unlimited” Fortran source code lines to be 250 columns, not 254.
685 *** AC_INIT and AS_INIT no longer embed (part of) the path to the
686 source directory in generated files.
688 We believe this was the only case where generated file contents
689 could change depending on the environment outside the source tree
690 itself. If you find any other cases please report them as bugs.
692 *** config.log properly escapes arguments in the header comment.
694 *** config.status --config output is now quoted in a more readable fashion.
696 ** Autotest enhancements
698 *** Autotest provides a new macro AT_DATA_UNQUOTED, similar to AT_DATA
699 but processing variable substitutions, command substitutions and
700 backslashes in the contents argument.
702 *** AC_CONFIG_TESTDIR will automatically pass EXEEXT to a testsuite (via
705 *** AT_TESTED arguments can use variable or command substitutions, including
706 in particular $EXEEXT
708 *** New macros AT_PREPARE_TESTS, AT_PREPARE_EACH_TEST, and AT_TEST_HELPER_FN.
710 These provide an official way to define testsuite-specific
711 initialization code and shell functions.
713 * Noteworthy changes in release 2.69 (2012-04-24) [stable]
715 ** Autoconf now requires perl 5.6 or better (but generated configure
716 scripts continue to run without perl).
718 * Noteworthy changes in release 2.68b (2012-03-01) [beta]
719 Released by Eric Blake, based on git versions 2.68.*.
721 ** Autoconf-generated configure scripts now unconditionally re-execute
722 themselves with $CONFIG_SHELL, if that's set in the environment.
724 ** The texinfo documentation no longer specifies "front-cover" or
725 "back-cover" texts, so that it may now be included in Debian's
728 ** Support for the Go programming language has been added. The new macro
729 AC_LANG_GO sets variables GOC and GOFLAGS.
731 ** AS_LITERAL_IF again treats '=' as a literal. Regression introduced in
734 ** The macro AS_EXECUTABLE_P, present since 2.50, is now documented.
738 - AC_PROG_LN_S and AS_LN_S now fall back on 'cp -pR' (not 'cp -p') if 'ln -s'
739 does not work. This works better for symlinks to directories.
741 - New macro AC_HEADER_CHECK_STDBOOL.
743 - New and updated macros for Fortran support:
745 AC_FC_CHECK_BOUNDS to enable array bounds checking
746 AC_F77_IMPLICIT_NONE and AC_FC_IMPLICIT_NONE to disable implicit integer
747 AC_FC_MODULE_EXTENSION to compute the Fortran 90 module name extension
748 AC_FC_MODULE_FLAG for the Fortran 90 module search path flag
749 AC_FC_MODULE_OUTPUT_FLAG for the Fortran 90 module output directory flag
750 AC_FC_PP_SRCEXT for preprocessed Fortran source files extensions
751 AC_FC_PP_DEFINE for the Fortran preprocessor define flag
753 * Noteworthy changes in release 2.68 (2010-09-22) [stable]
754 Released by Eric Blake, based on git versions 2.67.*.
756 ** AC_MSG_ERROR (and AS_ERROR) can once again be followed immediately by
757 'dnl'. Regression introduced in 2.66.
759 ** AC_INIT again allows URLs with '?' for its BUG-REPORT argument.
760 Regression introduced in 2.66.
762 ** AC_REPLACE_FUNCS again allows a non-literal argument, such as a shell
763 variable that expands to a list of functions to check. Regression
766 ** AT_BANNER() with empty argument will cause visual separation from previous
769 ** The macros AC_PREPROC_IFELSE, AC_COMPILE_IFELSE, AC_LINK_IFELSE, and
770 AC_RUN_IFELSE now warn if the first argument failed to use
771 AC_LANG_SOURCE or AC_LANG_PROGRAM to generate the conftest file
772 contents. A new macro AC_LANG_DEFINES_PROVIDED exists if you have
773 a compelling reason why you cannot use AC_LANG_SOURCE but must
776 ** The macro m4_define_default is now documented.
778 ** Symlinked config.cache files are supported; configure now tries to
779 update non-symlinked cache files atomically, so that concurrent configure
780 runs do not leave behind broken cache files. It is still unspecified
781 which subset or union of results is cached though.
783 ** Autotest testsuites should not contain long text lines any more, and be
784 portable even when very many test groups are used.
786 ** AT_CHECK semantics with respect to the Autotest variable $at_status and
787 shell execution environment of the arguments are documented now.
789 ** AC_FC_LIBRARY_LDFLAGS now tolerates output from newer gfortran.
791 ** Newly obsolete macros
792 The following macros have been marked obsolete. New programs
793 should use the corresponding Gnulib modules. Gnulib not only
794 detects a larger set of portability problems with these functions,
795 but also provides complete workarounds.
797 AC_FUNC_ERROR_AT_LINE AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK
798 AC_FUNC_MKTIME AC_FUNC_STRTOD
801 * Major changes in Autoconf 2.67 (2010-07-21) [stable]
802 Released by Eric Blake, based on git versions 2.66.*.
804 ** AC_CONFIG_SUBDIRS with more than one subdirectory at a time works again.
805 Regression introduced in 2.66.
807 ** AC_CHECK_SIZEOF of a pointer type works again. Regression introduced in
810 ** New macro AC_FC_LINE_LENGTH to accept long Fortran source code lines.
812 ** AC_PREPROC_IFELSE now keeps the preprocessed output in the conftest.i
813 file for inspection by the commands in the ACTION-IF-TRUE argument.
815 ** AC_INIT again allows parentheses and other characters that are literal
816 in single- or double-quoted strings, and in quoted and unquoted
817 here-documents, for its PACKAGE and VERSION arguments. Regression
820 ** autoreconf passes warning flags to new enough versions of aclocal.
822 ** Running an Autotest testsuite in parallel mode no longer triggers a
823 race condition that could cause the testsuite run to end early,
824 fixing a sporadic failure in autoconf's own testsuite. Bug present
825 since introduction of parallel tests in 2.63b.
828 * Major changes in Autoconf 2.66 (2010-07-02) [stable]
829 Released by Eric Blake, based on git versions 2.65.*.
831 ** AC_FUNC_MMAP works in C++ mode again. Regression introduced in 2.65.
833 ** Use of m4_divert without a named diversion now issues a syntax warning,
834 since it is seldom right to change diversions behind autoconf's back.
836 ** The macros AC_TYPE_INT8_T, AC_TYPE_INT16_T, AC_TYPE_INT32_T, and
837 AC_TYPE_INT64_T work again. Regression introduced in 2.65.
839 ** AC_PROG_INSTALL correctly uses 'shtool' again. Regression introduced
842 ** Autoconf should work on EBCDIC hosts.
844 ** AC_CHECK_DECL and AC_CHECK_DECLS accept optional function argument types
845 for overloaded C++ functions.
847 ** AS_SET_CATFILE accepts nonliterals in its variable name argument now.
849 ** Autotest testsuites accept an option --recheck to rerun tests that
850 failed or passed unexpectedly during the last non-debug testsuite run.
852 ** AC_ARG_ENABLE and AC_ARG_WITH now also accept '+' signs in '--enable-*'
853 and '--with-*' arguments, converting them to underscores for the variable
856 ** In configure scripts, loading CONFIG_SITE no longer searches PATH,
857 and problems in loading the configuration site files are diagnosed.
859 ** Autotest testsuites may optionally provide colored test results.
861 ** The previously undocumented Autotest macros AT_ARG_OPTION and
862 AT_ARG_OPTION_ARG have seen bug fixes and are documented now.
863 AT_ARG_OPTION has been changed in that the negative of a long option
864 --OPTION is now --no-OPTION rather than --noOPTION.
866 ** The macro AS_LITERAL_IF is slightly more conservative; text
867 containing shell quotes are no longer treated as literals.
868 Furthermore, a new macro, AS_LITERAL_WORD_IF, adds an additional
869 level of checking that no whitespace occurs in literals.
871 ** The macros AS_TR_SH and AS_TR_CPP no longer expand their results.
873 ** The following macros are now documented:
876 ** New macro AC_FC_FIXEDFORM to accept fixed-form Fortran.
879 * Major changes in Autoconf 2.65 (2009-11-21) [stable]
880 Released by Eric Blake, based on git versions 2.64.*.
882 ** Autoconf is now licensed under the General Public License version 3
883 or later (GPLv3+). As with earlier versions, the license includes
884 an exception clause so that you may release a configure script
885 generated by autoconf under the license of your own program.
887 ** New macros to support Objective C++.
888 AC_PROG_OBJCXX AC_PROG_OBJCXXCPP
890 ** The following undocumented autoconf macros, removed in Autoconf 2.64,
891 have been reinstated:
894 These macros are present only for backwards compatibility purposes.
896 ** The macro AC_LANG_COMPILER no longer fails on embedded systems that
897 lack fopen in the C library, such as AVR or RTEMS (regression
900 ** The AC_FC_FREEFORM macro no longer suffers from a whitespace bug that
901 made it fail with some Fortran compilers (regression introduced in
904 ** The AC_TYPE_UINT64_T and AC_TYPE_INT64_T macros have been fixed to no
905 longer mistakenly select a 32-bit type on some compilers (bug present
906 since macros were introduced in 2.59c).
908 ** The AC_FUNC_MMAP macro has been fixed to be portable to systems like
909 Cygwin (bug present since macro was introduced in 2.0).
911 ** The following documented autotest macros are new:
914 ** The following m4sugar macros now quote their expansion:
915 m4_toupper m4_tolower
917 ** The following m4sugar macros are new:
920 ** The m4sugar macro m4_text_wrap now copes with embedded quoting without
921 requiring quadrigraphs. For uses like AC_ARG_VAR([a], [[b c]]),
922 this gives the intuitive behavior of "[b c]" in the output (2.63
923 gave the output of "[b], [c]", and 2.64 encountered a failure).
925 ** The '$tmp' temporary directory used in config.status is documented for
928 ** config.status now provides a --config option to produce the configuration.
930 ** Many cache variables used by Autoconf's macros are now documented.
932 ** Configure scripts work better on DJGPP by avoiding a bug present in
933 the DJGPP port of bash 2.04 in handling 'return' in a shell
934 function (regression introduced in 2.64).
936 * Major changes in Autoconf 2.64 (2009-07-26) [stable]
937 Released by Eric Blake, based on git versions 2.63b.*.
939 ** Autoconf now requires GNU M4 1.4.6 or later. Earlier versions of M4
940 have a bug in regular expression handling that interferes with some
941 of the speedups provided since Autoconf 2.63. GNU M4 1.4.13 or
942 later is recommended.
944 ** AS_IF and AS_CASE have been taught to avoid syntax errors even when
945 given arguments that expand to just whitespace.
947 ** The following documented autoconf macros are new:
948 AC_ERLANG_SUBST_ERTS_VER
950 ** The autoheader tool now understands m4 macro arguments passed to
951 AC_DEFINE and AC_DEFINE_UNQUOTED.
953 ** Ensure AT_CHECK can support commands that include a # given with
954 proper m4 quoting. For shell comments, this is a new feature; for
955 non-shell comments, this fixes a regression introduced in 2.63b.
956 Additionally, AT_CHECK correctly supplies shell escapes for
957 metacharacters occurring in m4 macro expansions within the expected
958 stdout and stderr parameters.
960 ** The macro AT_CHECK now understands the concept of hard failure. If
961 a test exits with an unexpected status 99, cleanup actions for the
962 test are inhibited and the test is treated as a failure regardless
963 of AT_XFAIL_IF. It also understands the new directives
964 ignore-nolog, stdout-nolog, and stderr-nolog.
966 ** The following documented autotest macros are new:
967 AT_CHECK_UNQUOTED AT_FAIL_IF AT_SKIP_IF
969 ** The following documented m4sugar macros are new:
970 m4_argn m4_copy_force m4_default_nblank m4_default_nblank_quoted
971 m4_ifblank m4_ifnblank m4_rename_force
973 ** The autoconf testsuite now exercises all Erlang macros.
975 * Major changes in Autoconf 2.63b (2009-03-31) [beta]
976 Released by Eric Blake, based on git versions 2.63.*.
978 ** The manual is now shipped under the terms of the GNU FDL 1.3.
980 ** AC_REQUIRE now detects the case of an outer macro which first expands
981 then later indirectly requires the same inner macro. Previously,
982 this case led to silent out-of-order expansion (bug present since
983 2.50); it now issues a syntax warning, and duplicates the expansion
984 of the inner macro to guarantee dependencies have been met. See
985 the manual for advice on how to refactor macros in order to avoid
986 the bug in earlier autoconf versions and avoid increased script
987 size in the current version.
989 ** AC_DEFUN_ONCE has improved semantics. Previously, a macro declared
990 with AC_DEFUN_ONCE warned on a second invocation; and out-of-order
991 expansion was still possible. Now, dependencies are guaranteed,
992 and subsequent invocations are a silent no-op. This makes
993 AC_DEFUN_ONCE an ideal macro for silencing AC_REQUIRE warnings.
995 ** The following macros are now defined with AC_DEFUN_ONCE. This means
996 a subtle change in semantics; previously, an AC_DEFUN macro could
997 expand one of these macros multiple times or surround the macro
998 inside shell conditional text to bypass the effects of these
999 macros, but now the macro will expand exactly once, and prior to
1000 the start of any enclosing AC_DEFUN macro:
1001 AC_CANONICAL_BUILD AC_CANONICAL_HOST AC_CANONICAL_TARGET
1002 AC_HEADER_ASSERT AC_PROG_INSTALL AC_PROG_MKDIR_P
1003 AC_USE_SYSTEM_EXTENSIONS
1005 ** AC_LANG_ERLANG works once again (regression introduced in 2.61a).
1007 ** AC_HEADER_ASSERT is fixed so that './configure --enable-assert' no
1008 longer mistakenly disables assertions.
1010 ** AC_INIT now takes an optional fifth parameter that can be used to
1011 set AC_PACKAGE_URL, a URL for the package's home page; the URL is
1012 used in 'configure --help' and is also available via AC_DEFINE.
1014 ** Autotest testsuites accept an option --jobs[=N] for parallel testing.
1015 This feature is still in testing, and may not work on every
1016 platform, help in improving it would be appreciated.
1018 ** Autotest testsuites do not attempt to write startup error messages
1019 to the log file before that is opened (regression introduced in 2.63).
1021 ** Configure scripts now use shell functions. This feature leads to
1022 smaller configure files and faster execution.
1024 ** Present But Cannot Be Compiled: Autoconf will now proceed with
1025 the compiler's result if a header is present but cannot be compiled.
1026 The warning is still printed, and you should really fix it by
1027 providing a fourth parameter to AC_CHECK_HEADER/AC_CHECK_HEADERS.
1029 ** Autoreconf added aclocal to the set of programs affected by the
1030 'autoreconf -I dir' option.
1032 ** The following documented m4sugar macros are new:
1033 m4_chomp m4_chomp_all m4_cleardivert m4_curry m4_default_quoted
1034 m4_esyscmd_s m4_map_args m4_map_args_pair m4_map_args_sep
1035 m4_map_args_w m4_set_map m4_set_map_sep m4_stack_foreach
1036 m4_stack_foreach_lifo m4_stack_foreach_sep
1037 m4_stack_foreach_sep_lifo
1039 ** The following m4sugar macros are documented now, but in some cases
1040 with slightly different semantics than what the previous
1041 undocumented version had:
1042 m4_copy m4_dumpdefs m4_rename m4_version_prereq
1044 ** The m4sugar macro m4_expand has been taught to handle unterminated
1045 comments and shell case statements. As a result, it is used
1046 internally in more places, such as AC_DEFINE and AT_CHECK. Most
1047 uses of AC_DEFINE and AT_CHECK should not behave any differently;
1048 however, it may be necessary to add double-quoting around
1049 unbalanced '(' where single-quoting used to be sufficient.
1051 ** The following documented m4sh macros are new:
1052 AS_INIT_GENERATED AS_LINENO_PREPARE AS_ME_PREPARE AS_SET_STATUS
1053 AS_VAR_APPEND AS_VAR_ARITH AS_VAR_COPY
1055 ** The following m4sh macros are documented now, but in some cases
1056 with slightly different semantics than what the previous
1057 undocumented version had:
1058 AS_ECHO AS_ECHO_N AS_ESCAPE AS_EXIT AS_LITERAL_IF AS_UNSET
1059 AS_VAR_IF AS_VAR_POPDEF AS_VAR_PUSHDEF AS_VAR_SET AS_VAR_SET_IF
1060 AS_VAR_TEST_SET AS_VERSION_COMPARE
1062 ** The m4sh macros AS_IF and AS_CASE can now be used in shell lists.
1063 The responsibility for supplying a trailing newline now belongs to
1064 the call site, but since most users did not add dnl, this generally
1065 results in fewer empty lines in configure.
1068 * Major changes in Autoconf 2.63 (2008-09-09) [stable]
1069 Released by Eric Blake, based on git versions 2.62.*.
1071 ** AC_C_BIGENDIAN does not mistakenly report "universal" for some
1072 bigendian hosts, a regression introduced with universal binary
1075 ** AC_PATH_X now includes /lib64 and /usr/lib64 in its list of default
1076 library directories.
1078 ** AC_USE_SYSTEM_EXTENSIONS no longer conflicts with an external
1079 AC_DEFINE([__EXTENSIONS__]). This fixes a regression introduced in
1080 2.62 when using macros such as AC_AIX that were made obsolete in
1081 favor of the more portable AC_USE_SYSTEM_EXTENSIONS.
1083 ** AC_CHECK_TARGET_TOOLS is usable in the non-cross-compile case.
1085 ** Newly obsolete macros
1086 The following macro has been marked obsolete, since current porting
1087 targets can safely assume C89 semantics that signal handlers return
1088 void. We have no current plans to remove the macro.
1092 ** The macros m4_map and m4_map_sep now ignore any list elements
1093 consisting of just empty quotes, and m4_map_sep now expands its
1094 separator. This fixes a regression in 2.62 when these macros were
1095 first documented, for the sake of clients expecting the semantics
1096 that these macros had prior to that time. The new macros m4_mapall
1097 and m4_mapall_sep, along with extra quoting of the separator, can
1098 be used to get the semantics that m4_map_sep had in 2.62.
1100 ** Clients of m4_expand, such as AS_HELP_STRING and AT_SETUP, can now
1101 handle properly quoted but otherwise unbalanced parentheses (for
1102 some macros, this fixes a regression in 2.62).
1104 ** Two new quadrigraphs have been introduced: @{:@ for (, and @:}@ for ),
1105 allowing the output of unbalanced parentheses in more contexts.
1107 ** The following m4sugar macros are new:
1108 m4_cleardivert m4_joinall m4_mapall m4_mapall_sep m4_reverse
1109 m4_set_add m4_set_add_all m4_set_contains m4_set_contents
1110 m4_set_delete m4_set_difference m4_set_dump m4_set_empty
1111 m4_set_foreach m4_set_intersection m4_set_list m4_set_listc
1112 m4_set_remove m4_set_size m4_set_union
1114 ** The following m4sugar macros now accept multiple arguments, as is the
1115 case with underlying m4:
1116 m4_defn m4_popdef m4_undefine
1118 ** The following m4sugar macros now guarantee linear scaling; they
1119 previously had linear scaling with m4 1.6 but quadratic scaling
1120 when using m4 1.4.x. All macros built on top of these also gain
1121 the scaling improvements.
1122 m4_bmatch m4_bpatsubsts m4_case m4_cond m4_do m4_dquote_elt
1123 m4_foreach m4_join m4_list_cmp m4_map m4_map_sep m4_max
1126 ** AT_KEYWORDS once again performs expansion on its argument, such that
1127 AT_KEYWORDS([m4_if([$1], [], [default])]) no longer complains about
1128 the possibly unexpanded m4_if [regression introduced in 2.62].
1130 ** Config header templates '#undef UNDEFINED /* comment */' do not lead to
1131 nested comments any more; regression introduced in 2.62.
1134 * Major changes in Autoconf 2.62 (2008-04-05) [stable]
1135 Released by Eric Blake, based on git versions 2.61a.*.
1137 ** Many optimizations have been applied to make overall execution faster.
1139 ** Autotest now makes use of shell functions.
1141 ** config.status now uses awk instead of sed also for config headers.
1143 - As a side effect, AC_DEFINE and AC_DEFINE_UNQUOTED now handle multi-line
1144 values, i.e., backslash-newline combinations are handled correctly.
1145 Further, for config headers, the total size of values is not limited by
1146 the POSIX length limit of text lines any more, only each single line.
1148 ** New config variable 'top_build_prefix'.
1150 ** New Autoconf macros:
1151 AC_AUTOCONF_VERSION AC_OPENMP AC_PATH_PROGS_FEATURE_CHECK
1153 ** AC_C_BIGENDIAN now supports universal binaries a la Mac OS X.
1155 ** AC_C_RESTRICT now prefers to #define 'restrict' to a variant spelling
1156 like '__restrict' if the variant spelling is available, as this is
1157 more likely to work when mixing C and C++ code.
1159 ** AC_CHECK_ALIGNOF's type argument T is now documented better: it must
1160 be a string of tokens such that "T y;" is a valid member declaration
1163 ** AC_CHECK_SIZEOF now accepts objects as well as types: the general rule
1164 is that sizeof (X) works, then AC_CHECK_SIZEOF (X) should work.
1166 ** AC_CHECK_TYPE and AC_CHECK_TYPES now work on any C type-name; formerly,
1167 they did not work for function types. In C++, they now work on any
1168 type-id that can be the operand of sizeof; this is similar to C,
1169 except it excludes anonymous struct and union types. Formerly,
1170 some (but not all) C++ types involving anonymous struct and union
1171 were accepted, though this was not documented.
1173 ** AC_CONFIG_LINKS now prefers to link against files in the build tree
1174 if found, and it works to link against a file of the same name in
1175 the source tree, even if both trees coincide.
1177 ** AC_INIT no longer alters $@; regression introduced in 2.60.
1179 ** AC_USE_SYSTEM_EXTENSIONS now defines _ALL_SOURCE for Interix platforms.
1181 ** AS_HELP_STRING no longer underquotes its first argument; it also handles
1182 the case where the first argument contains single-quoted commas.
1183 For example, "AS_HELP_STRING([-a, [--arg[=foo]]], [bar])" produces:
1184 " -a, --arg[=foo] bar"
1185 Additionally, the macro now takes two additional arguments,
1186 indent-column and wrap-column; these should not normally be needed,
1187 but can be used to fine-tune how the output text is wrapped.
1189 ** AC_PROG_INSTALL now requires an install program that can install multiple
1190 files into a target directory.
1192 ** The command 'autoconf -' now correctly processes a file from stdin.
1194 ** 'autoreconf -m' now honors $MAKE.
1196 ** For all of the directory arguments for 'configure', such as '--prefix'
1197 or '--bindir', trailing slashes are stripped. As an example, if
1198 tab completion in the user's shell appends trailing slashes, the
1199 command './configure --prefix=/usr/' will still result in an
1200 expanded libdir value of /usr/lib, not /usr//lib.
1202 ** 'configure --help=recursive' now works in read-only trees and from
1203 unconfigured build trees.
1205 ** If precious variables differ only in whitespace, then the cache consistency
1206 check warns instead of fails, and reuses the old value.
1208 ** AT_BANNER is now documented.
1210 ** AT_SETUP now handles macro expansions properly when calculating line
1213 ** Autotest now determines $srcdir correctly.
1215 ** Testsuites built by autotest now accept a -C/--directory=DIR option
1216 to adjust the working directory prior to creating files.
1218 ** Autoconf now requires GNU M4 1.4.5 or later. Earlier versions of M4 have
1219 a bug in macro tracing that interferes with the interaction between
1220 Autoconf and Automake. GNU M4 1.4.11 or later is recommended. The
1221 configure search for a working M4 is improved.
1223 ** For portability with the eventual M4 2.0, macros should no longer use
1224 anything larger than $9 to refer to arguments.
1226 ** Documentation for m4sugar is improved.
1228 - The following macros were previously available as undocumented
1229 interfaces; the macros are now documented as stable interfaces.
1231 __oline__ m4_assert m4_bmatch m4_bpatsubsts m4_car m4_case
1232 m4_cdr m4_default m4_divert_once m4_divert_pop m4_divert_push
1233 m4_divert_text m4_do m4_errprintn m4_fatal m4_flatten
1234 m4_ifndef m4_ifset m4_ifval m4_ifvaln m4_location
1235 m4_n m4_shiftn m4_strip m4_warn
1237 - The following macros were previously available as undocumented
1238 interfaces, but had bug fixes or semantic changes as part of this
1239 release. Packages that relied on the undocumented behavior
1240 should be analyzed to make sure they will still work with the
1241 new documented behavior.
1243 m4_cmp m4_list_cmp m4_join m4_map m4_map_sep m4_sign
1244 m4_text_box m4_text_wrap m4_version_compare
1246 - The m4_wrap macro used to have unspecified order, but now
1247 guarantees FIFO order. m4_wrap_lifo was added to guarantee LIFO
1250 - Packages using the undocumented m4sugar macro m4_PACKAGE_VERSION
1251 should consider using the new AC_AUTOCONF_VERSION instead.
1253 - m4sugar macros that are not documented in the manual are still
1254 deemed experimental, and should not be used outside of Autoconf.
1256 ** The m4sugar macros m4_append and m4_append_uniq, first documented in
1257 2.60, have been fixed to treat both the string and the separator
1258 arguments consistently with regards to quoting. Prior to this fix,
1259 m4_append_uniq could mistakenly duplicate entries if the expansion
1260 of the separator resulted in a different string (for example, if it
1261 contained quotes, a comma, or a macro name). However, it means
1262 that programs previously using
1263 m4_append([name], [string], [[, ]])
1264 are now using a four-character separator instead of the intended
1265 comma and space. If you need portability to earlier versions of
1266 Autoconf, you can insert the following snippet after AC_INIT but
1267 before any other macro expansions, to enforce the new semantics:
1268 m4_pushdef([m4_append], [m4_define([$1],
1269 m4_ifdef([$1], [m4_defn([$1])[$3]])[$2])])
1270 Additionally, m4_append_uniq now takes optional parameters that can
1271 be used to take action depending on whether anything was appended,
1272 and warns if a non-empty separator occurs within the string being
1273 appended, since that can lead to duplicates.
1275 ** The following m4sugar macros are new:
1276 m4_append_uniq_w m4_apply m4_combine m4_cond m4_count
1277 m4_dquote_elt m4_echo m4_expand m4_ignore m4_make_list m4_max
1278 m4_min m4_newline m4_shift2 m4_shift3 m4_unquote m4_wrap_lifo
1280 ** Warnings are now generated by default when an installer invokes
1281 'configure' with an unknown --enable-* or --with-* option.
1282 These warnings can be disabled with the new AC_DISABLE_OPTION_CHECKING
1283 macro, or by invoking 'configure' with --disable-option-checking.
1285 ** Existing obsolete macros
1286 The documentation for the following macros is adjusted to make it
1287 more clear that they have previously been marked obsolete, as their
1288 functionality can be accomplished by other macros. We have no
1289 current plans to remove them from Autoconf.
1291 AC_ENABLE AC_STRUCT_ST_BLKSIZE AC_STRUCT_ST_RDEV AC_WITH
1293 ** Newly obsolete macros
1294 The following macros have been marked obsolete, as they only
1295 perform a subset of AC_USE_SYSTEM_EXTENSIONS. We have no current
1296 plans to remove them.
1298 AC_AIX AC_GNU_SOURCE AC_ISC_POSIX AC_MINIX
1300 ** AC_C_LONG_DOUBLE is obsolescent.
1301 The documentation now says that AC_C_LONG_DOUBLE is obsolescent: it
1302 tests for problems that are so old that it is no longer of
1303 practical importance on current systems. New programs need not use
1304 AC_C_LONG_DOUBLE. We have no current plans to remove it.
1306 ** AC_DIAGNOSE, AC_WARNING, and AC_FATAL are obsolescent.
1307 The documentation now favors the use of M4sugar macros m4_warn and
1308 m4_fatal, since the naming makes it more obvious that the
1309 diagnostics are associated with M4 expansion (ie. when running
1310 'autoconf'), and offers less confusion with the AC_MSG_ERROR,
1311 AC_MSG_FAILURE, and AC_MSG_WARN macros which manage diagnostics
1312 when running 'configure'. We have no current plans to remove these
1316 * Major changes in Autoconf 2.61a (2006-12-11)
1318 ** AC_FUNC_FSEEKO was broken in 2.61; it didn't make fseeko and ftello visible
1319 on many platforms. This has been fixed.
1321 ** AC_FUNC_SETVBUF_REVERSED is now obsolete. It is still defined for backward
1322 compatibility but it does nothing. The macro was already
1323 obsolescent, as the last systems to have the problem were those
1324 based on SVR2, which became obsolete in 1987. The macro had bugs
1325 on some modern systems and could no longer be maintained reliably
1326 due to lack of ancient systems to test it on.
1328 ** config.status now uses awk instead of sed for most substitutions, for speed.
1330 - As a side effect multi-line values of substituted variables no
1331 longer have a small limit in total size, though for portability
1332 each line should not exceed the POSIX length limit for text lines.
1334 - It is now documented that Makefile.in should not contain
1335 overlapping variable occurrences, e.g., @VAR1@VAR2@.
1336 Autoconf's behavior was always iffy in such cases, and the
1337 awk implementation has changed the behavior.
1339 ** Many uses of 'echo' have been rewritten so that Autoconf-generated
1340 scripts have fewer problems with strings or file names containing
1341 embedded special characters such as backslash or leading "-". This
1342 was implemented by using 'printf '%s\n' "$foo"' instead of 'echo
1343 "$foo"' when printf works. Due to the implementation technique
1344 used, Autoconf-generated scripts now run considerably more slowly
1345 on ancient implementations lacking printf. However, this should
1346 not be a problem, since Autoconf-generated scripts in practice
1347 invariably find a more-modern shell these days.
1350 * Major changes in Autoconf 2.61 (2006-11-17)
1352 ** New macros AC_C_FLEXIBLE_ARRAY_MEMBER, AC_C_VARARRAYS.
1354 ** AC_ARG_ENABLE and AC_ARG_WITH now allow '.' in feature and package names.
1357 * Major changes in Autoconf 2.60b (2006-10-22)
1360 Autoconf-generated shell scripts no longer export BIN_SH, due to
1361 configuration hassles with this. Installers who need BIN_SH in
1362 their environment should set it before invoking 'configure' and
1363 'make'. As far as we know, this affects only Unixware installations.
1365 ** Obsolescent macros
1366 The documentation now says that the following macros are obsolescent,
1367 as they are superseded by Gnulib:
1369 AC_FUNC_FNMATCH AC_FUNC_FNMATCH_GNU AC_FUNC_GETLOADAVG
1372 New programs should use the Gnulib counterparts of these macros.
1373 We have no current plans to remove them from Autoconf.
1375 ** AC_COMPUTE_INT no longer caches or reports results.
1377 ** AC_CHECK_DECL now also works with aggregate objects.
1379 ** AC_USE_SYSTEM_EXTENSIONS now defines _TANDEM_SOURCE for NonStop platforms.
1381 ** GNU M4 1.4.7 or later is now recommended.
1384 New M4sugar macro, which is more secure than the POSIX M4 maketemp.
1387 Now an alias for m4_mkstemp.
1389 * Major changes in Autoconf 2.60a (2006-08-25)
1391 ** GNU M4 1.4.6 or later is now recommended.
1393 ** The check for C99 now tests for varargs macros, as documented.
1394 It also tests that the preprocessor supports 64-bit integers.
1396 ** Autoconf now uses constructs like "#ifdef HAVE_STDLIB_H" rather than
1397 "#if HAVE_STDLIB_H", so that it now works with "gcc -Wundef -Werror".
1399 ** The functionality of the undocumented _AC_COMPUTE_INT is now provided
1400 by a public and documented macro, AC_COMPUTE_INT. The parameters to the
1401 two macros are different, so autoupdate will not change the old private name
1402 to the new one. _AC_COMPUTE_INT may be removed in a future release.
1404 ** AC_TYPE_LONG_LONG_INT and AC_TYPE_UNSIGNED_LONG_LONG_INT now require
1405 that long long types be at least 64 bits wide, as C99 and tradition
1406 requires. Formerly, they accepted implementations of any width.
1409 * Major changes in Autoconf 2.60
1411 Released 2006-06-23, by Ralf Wildenhues.
1413 ** Autoconf no longer depends on whether m4wrap is FIFO (as Posix requires)
1414 or LIFO (as in GNU M4 1.4.x). GNU M4 2.0 is expected to conform to Posix
1415 here, so m4wrap/m4_wrap users should no longer depend on LIFO behavior.
1417 ** Provide a way to turn off warnings about the changed directory variables.
1419 * Major changes in Autoconf 2.59d
1421 Released 2006-06-05, by Ralf Wildenhues.
1423 ** GNU make now recommended for VPATH builds
1424 INSTALL now suggests VPATH builds (e.g., "sh ../srcdir/configure")
1425 only if you use GNU make. In practice, other 'make' implementations
1426 have too many subtle incompatibilities in their support for VPATH.
1427 Many packages (including Autoconf itself) are portable to other
1428 'make' implementations, but some packages are not, and recommending
1429 GNU make keeps the installation instructions simpler.
1431 ** Even more safety checks for the new Directory variables:
1432 Warn about suspicious '${datarootdir}' found in config files output.
1434 ** AC_TRY_COMMAND, AC_TRY_EVAL, ac_config_guess, ac_config_sub, ac_configure
1435 These never-documented macros and variables have been marked with
1436 comments saying that they may be removed in a future release,
1437 because their use can lead to unintended code being executed.
1438 If you need functionality that only these macros or variables
1439 currently supply, please write bug-autoconf@gnu.org.
1441 ** AC_SUBST, AC_DEFINE
1442 Literal arguments to these are passed to m4_pattern_allow now.
1445 Passing 'ac_cv_prog_cc_stdc=no' to 'configure' now sets ac_cv_prog_cc_c99
1446 and ac_cv_prog_cc_c89 to 'no' as well, for backward compatibility with
1447 obsolete K&R tests in the Automake test suite.
1456 Now more robust with special characters in file names, or when
1457 multiple processes create the same directory at the same time.
1459 ** Obsolescent macros
1460 The documentation now says that the following macros are obsolescent:
1461 they test for problems that are so old that they are no longer of
1462 practical importance on current systems.
1464 AC_C_BACKSLASH_A AC_FUNC_MEMCMP AC_HEADER_DIRENT
1465 AC_C_CONST AC_FUNC_SELECT_ARGTYPES AC_HEADER_STAT
1466 AC_C_PROTOTYPES AC_FUNC_SETPGRP AC_HEADER_STDC
1467 AC_C_STRINGIZE AC_FUNC_SETVBUF_REVERSED AC_HEADER_SYS_WAIT
1468 AC_C_VOLATILE AC_FUNC_STAT AC_HEADER_TIME
1469 AC_FUNC_CLOSEDIR_VOID AC_FUNC_STRFTIME AC_ISC_POSIX
1470 AC_FUNC_GETPGRP AC_FUNC_UTIME_NULL AC_PROG_GCC_TRADITIONAL
1471 AC_FUNC_LSTAT AC_FUNC_VPRINTF AC_STRUCT_TM
1473 New programs need not use these macros. We have no current plans to
1477 For compatibility with future Libtool 2.0, autoreconf will invoke
1478 libtoolize with the option '--ltdl' now, if LT_CONFIG_LTDL_DIR is
1481 * Major changes in Autoconf 2.59c
1483 Released 2006-04-12, by Ralf Wildenhues.
1485 ** The configure command now redirects standard input from /dev/null,
1486 to help avoid problems with subsidiary commands that might mistakenly
1487 read standard input. AS_ORIGINAL_STDIN_FD points to the original
1488 standard input before this redirection, if you really want configure to
1489 read from standard input.
1491 ** Directory variables adjusted to recent changes in the GNU Coding Standards.
1492 The following directory variables are new:
1494 datarootdir read-only architecture-independent data root [PREFIX/share]
1495 localedir locale-specific message catalogs [DATAROOTDIR/locale]
1496 docdir documentation root [DATAROOTDIR/doc/PACKAGE]
1497 htmldir html documentation [DOCDIR]
1498 dvidir dvi documentation [DOCDIR]
1499 pdfdir pdf documentation [DOCDIR]
1500 psdir ps documentation [DOCDIR]
1502 The following variables have new default values:
1504 datadir read-only architecture-independent data [DATAROOTDIR]
1505 infodir info documentation [DATAROOTDIR/info]
1506 mandir man documentation [DATAROOTDIR/man]
1508 This means that if you use any of '@datadir@', '@infodir@', or
1509 '@mandir@' in a file, you will have to ensure '${datarootdir}' is
1510 defined in this file. As a temporary measure, if any of those are
1511 found but no mention of 'datarootdir', the substitutions will be
1512 replaced with values that do not contain '${datarootdir}', and a
1513 warning will be issued.
1515 ** @top_builddir@ is now a dir name: it is always nonempty and doesn't have
1516 a trailing slash. Similar change will be made to ac_top_builddir in a
1517 future release; the old style value, which matches (../)*, is (and will
1518 continue to be) available as ac_top_build_prefix.
1521 New macro to check for support of 'typeof' syntax a la GNU C.
1523 ** AC_CHECK_DECLS_ONCE, AC_CHECK_FUNCS_ONCE, AC_CHECK_HEADERS_ONCE
1524 New "once-only" variants of commonly-used macros, to make 'configure'
1525 smaller and faster in common cases.
1528 New macro to check for strtold with C99 semantics.
1531 New macro that lets builder disable assertions at 'configure'-time.
1534 Now checks for X11/Xlib.h and XrmInitialize (X proper) rather than
1535 X11/Intrinsic.h and XtMalloc (Xt).
1537 ** AC_PRESERVE_HELP_ORDER
1538 New macro that causes 'configure' to display help strings for AC_ARG_ENABLE
1539 and AC_ARG_WITH arguments in one region, in the order defined. The default
1540 behavior is to group options of each classes separately.
1542 ** AC_PROG_CC, AC_PROG_CXX
1543 No longer automatically arrange to declare the 'exit' function of C,
1544 when a C++ compiler is used. Standard Autoconf macros no longer use
1545 'exit', so this is no longer an issue for them. If you use C++, and
1546 want to call 'exit', you'll have to arrange for its declaration
1547 yourself. But we now suggest you return from 'main' instead.
1549 ** AC_PROG_CC_C89, AC_PROG_CC_C99
1550 New macros for ISO C99 support. AC_PROG_CC_C89 and AC_PROG_CC_C99
1551 check for ANSI C89 and ISO C99 support respectively.
1554 Has been unobsoleted, and will check if the compiler supports ISO
1555 C99, falling back to ANSI C89 if not. ac_cv_prog_cc_stdc is
1556 retained for backwards compatibility, assuming the value of
1557 ac_cv_prog_cc_c99 or ac_cv_prog_cc_c89 (whichever is valid, in
1560 ** AC_STRUCT_DIRENT_D_INO, AC_STRUCT_DIRENT_D_TYPE
1561 New macros for checking commonly-used members of struct dirent.
1564 The substituted value can now contain newlines.
1567 The substitution now occurs only when @variable@ is on a line by itself,
1568 optionally surrounded by spaces and tabs. The whole line is replaced.
1570 ** AC_TYPE_LONG_DOUBLE, AC_TYPE_LONG_DOUBLE_WIDER
1571 New macros to check for long double, and whether it is wider than double.
1572 The old macro AC_C_TYPE_LONG_DOUBLE has been marked as obsolete;
1573 applications should switch to the new macro.
1575 ** AC_TYPE_INT8_T, AC_TYPE_INT16_T, AC_TYPE_INT32_T, AC_TYPE_INT64_T,
1576 AC_TYPE_INTMAX_T, AC_TYPE_INTPTR_T, AC_TYPE_LONG_LONG_INT, AC_TYPE_SSIZE_T,
1577 AC_TYPE_UINT8_T, AC_TYPE_UINT16_T, AC_TYPE_UINT32_T, AC_TYPE_UINT64_T,
1578 AC_TYPE_UINTMAX_T, AC_TYPE_UINTPTR_T, AC_TYPE_UNSIGNED_LONG_LONG_INT
1579 New macros to check for C99 and POSIX types.
1581 ** AC_USE_SYSTEM_EXTENSIONS
1582 New macro to enable extensions to Posix.
1585 New macro which is defined to the name of the first declared config header
1586 or undefined if no config headers have been declared yet.
1589 The macro correctly handles quadrigraphs now.
1591 ** AS_BOURNE_COMPATIBLE, AS_SHELL_SANITIZE, AS_CASE
1592 These macros are new or published now.
1595 New macro for copyright notices in testsuite files.
1597 ** ALLOCA, LIBOBJS, LTLIBOBJS
1598 Object names added to these variables are now prefixed with '${LIBOBJDIR}',
1599 as in '${LIBOBJDIR}alloca.o'. LIBOBJDIR is meant to be defined from
1600 'Makefile.in' in case the object files lie in a different directory.
1601 The LIBOBJDIR feature is experimental.
1604 Supports --no-recursive now.
1606 ** New macros to support Erlang/OTP.
1607 New macros for configuring paths to Erlang tools and libraries:
1608 AC_ERLANG_PATH_ERLC, AC_ERLANG_NEED_ERLC, AC_ERLANG_PATH_ERL,
1609 AC_ERLANG_NEED_ERL, AC_ERLANG_CHECK_LIB, AC_ERLANG_SUBST_ROOT_DIR,
1610 AC_ERLANG_SUBST_LIB_DIR.
1612 New macros for configuring installation of Erlang libraries:
1613 AC_ERLANG_SUBST_INSTALL_LIB_DIR, AC_ERLANG_SUBST_INSTALL_LIB_SUBDIR.
1615 ** The manual now mentions Gnulib more prominently.
1617 ** New macros to support Objective C.
1618 AC_PROG_OBJC, AC_PROG_OBJCPP.
1620 * Major changes in Autoconf 2.59b
1622 Released 2004-08-20, by Paul Eggert.
1625 New macro that computes the default alignment of a type.
1627 ** AC_CHECK_TOOL, AC_PATH_TOOL, AC_CHECK_TOOLS
1628 When cross-compiling, these macros will give a warning if the tool
1629 is not prefixed. In the future, unprefixed cross tools will not
1630 be detected; please consult the info documentation for information
1631 about the reason of this change.
1633 ** AC_CHECK_TARGET_TOOL, AC_PATH_TARGET_TOOL, AC_CHECK_TARGET_TOOLS
1634 New macros that detect programs whose name is prefixed with the
1635 target type, if the build type and target type are different.
1637 ** AC_REQUIRE_AUX_FILE
1638 New trace macro that declares expected auxiliary files.
1641 New macro that tests for a grep program that accepts as a long a line
1644 ** AC_PROG_EGREP, AC_PROG_FGREP
1645 These macros now require AC_PROG_GREP, and try EGREP="$GREP -E" and
1646 FGREP="$GREP -F" respectively if possible, or else run a path search for
1647 a program that accepts as long a line as possible.
1650 New macro that tests for a sed program that truncates as few characters
1653 * Major changes in Autoconf 2.59
1655 Released 2003-11-04, by Akim Demaille
1657 ** ac_abs_builddir etc.
1658 Absolute file names were actually relative in 2.58.
1660 * Major changes in Autoconf 2.58
1662 Released 2003-11-04, by Akim Demaille
1665 core.* files are no longer removed, as they may be valid user files.
1667 ** autoreconf and auxiliary directory
1668 Autoreconf creates the auxiliary directory if needed. This is
1669 especially useful for initial "bootstrapping" of fresh CVS checkouts.
1671 ** AC_CONFIG_MACRO_DIR
1672 Use this macro to declare the directory for local M4 macros for aclocal.
1675 No longer includes twice the same file in LIBOBJS if invoked
1678 ** AC_CONFIG_COMMANDS
1679 The directory for its first argument is automatically created. For
1682 AC_CONFIG_COMMANDS([src/modules.hh], [...])
1684 $top_builddir/src/ is created if needed.
1686 ** Autotest and local.at
1687 The optional file local.at is always included in Autotest test suites.
1690 The warnings are always issued, including with cached runs.
1691 This became a significant problem since aclocal and automake can
1692 run autoconf behind the scene.
1694 ** autoheader warnings
1695 The warnings of autoheader can be turned off, using --warning.
1696 For instance, -Wno-obsolete disables the complaints about acconfig.h
1697 and other deprecated constructs.
1700 AC_C_RESTRICT, AC_INCLUDES_DEFAULT, AC_LANG_ASSERT, AC_LANG_WERROR,
1703 ** AC_DECL_SYS_SIGLIST
1707 Now checks that mktime is the inverse of localtime.
1709 ** Improve DJGPP portability
1710 The Autoconf tools and configure behave better under DJGPP.
1712 ** Present But Cannot Be Compiled
1713 New FAQ section dedicated to the mystic
1715 configure: WARNING: pi.h: present but cannot be compiled
1716 configure: WARNING: pi.h: check for missing prerequisite headers?
1717 configure: WARNING: pi.h: proceeding with the preprocessor's result
1720 ** Concurrent executions of autom4te
1721 autom4te now locks its internal files, which enables concurrent
1722 executions of autom4te, likely to happen if automake, autoconf,
1723 autoheader etc. are run simultaneously.
1726 Use of Libtool 1.5 and higher is encouraged. Compatibility with
1727 Libtool pre-1.4 is not checked.
1730 Testsuites no longer rerun failed tests in verbose mode; instead,
1731 failures are logged while the test is run.
1733 In addition, expected failures can be marked as such.
1735 * Major changes in Autoconf 2.57
1737 Released 2002-12-03 by Paul Eggert.
1739 Bug fixes for problems with AIX linker, with freestanding C compilers,
1740 with GNU M4 limitations, and with obsolete copies of GNU documents.
1742 The Free Documentation License has been upgraded from 1.1 to 1.2.
1744 * Major changes in Autoconf 2.56
1746 Released 2002-11-15 by Akim Demaille.
1748 One packaging problem fixed (config/install-sh was not executable).
1750 * Major changes in Autoconf 2.55
1752 Released 2002-11-14 by Akim Demaille.
1756 Have your configure.ac checked by autoscan ("autoscan").
1757 Try the warning options ("autoreconf -fv -Wall").
1761 - AC_CHECK_HEADER, AC_CHECK_HEADERS
1762 More information on proper use.
1764 - Writing Test Programs
1766 This sections explains how to write good test sources to use with
1767 AC_COMPILE_IFELSE etc. It documents AC_LANG_PROGRAM and so forth.
1769 - AC_FOO_IFELSE vs. AC_TRY_FOO
1771 Explains why Autoconf moves from AC_TRY_COMPILE etc. to
1772 AC_COMPILE_IFELSE and AC_LANG_PROGRAM etc.
1776 - Is more robust to different Gettext installations.
1778 - Produces messages (when --verbose) to be understood by Emacs'
1781 - Supports -W/--warnings.
1784 Once the GNU Build System reinstalled, run './config.status
1785 --recheck && ./config.status && make' if possible.
1789 - Supports --cache, and --no-cache.
1791 - ~/.autom4te.cfg makes it possible to disable the caching mechanism
1792 (autom4te.cache). See 'Customizing autom4te' in the documentation.
1799 Support for the obsoleted options -m, --macrodir, -l, --localdir is
1800 dropped in favor of the safer --include/--prepend-include scheme.
1805 AC_COMPILER_IFELSE, AC_FUNC_MBRTOWC, AC_HEADER_STDBOOL,
1806 AC_LANG_CONFTEST, AC_LANG_SOURCE, AC_LANG_PROGRAM, AC_LANG_CALL,
1807 AC_LANG_FUNC_TRY_LINK, AC_MSG_FAILURE, AC_PREPROC_IFELSE.
1810 Obsoleted macros are kept for Autoconf backward compatibility, but
1811 should be avoided in configure.ac. Running autoupdate is advised.
1812 AC_DECL_SYS_SIGLIST.
1814 - AC_DEFINE/AC_DEFINE_UNQUOTED
1816 We have to stop using the old compatibility scheme --that tried to
1817 avoid useless backslashes-- because Libtool 1.4.3 contains a
1819 AC_DEFINE([error_t], [int],
1820 [Define to a type to use for \`error_t' if it is not
1821 otherwise available.])
1823 We have to quote the single quotes and backslashes with \. The old
1824 compatibility scheme saw that ` was backslashed, and therefore did
1825 not quote the single quote... Failure. Hence, Autoconf 2.54 is not
1826 compatible with Libtool. Autoconf 2.55 is, but in some cases might
1827 produce more \ than wanted.
1829 Please, note that in the future the same problem will happen with
1830 AC_MSG_*: use 'autoreconf -f -Wall'.
1834 - Portability of the Autoconf package to Solaris.
1836 - Spurious warnings caused by config.status.
1837 This bug is benign, but painful: on some systems (typically
1838 FreeBSD), warnings such as:
1840 config.status: creating Makefile
1841 mv: Makefile: set owner/group (was: 1357/0): Operation not permitted
1843 could be issued. This is fixed.
1846 Simultaneous executions of config.status are possible again.
1848 - Precious variables accumulation
1850 config.status could stack several copies of the precious variables
1854 ** Plans for later versions
1856 - ./configure <host>
1858 The compatibility hooks with the old scheme will be completely
1859 removed. Please, advice/use '--build', '--host', and '--target'
1862 - AC_CHECK_HEADER, AC_CHECK_HEADERS
1864 The tests will be stricter, please make sure your invocations are
1869 Shell functions will gradually be introduced, probably starting with
1870 Autotest. If you know machines which are in use that you suspect
1871 *not* to support shell functions, please run the test suite of
1872 Autoconf 2.55 on it, and report the results to
1873 bug-autoconf@gnu.org.
1877 Special characters in AC_MSG_* need not be quoted. Currently,
1878 Autoconf has heuristics to decide when a string is escaped, or has
1879 to be escaped. This scheme is fragile, and will be removed; the
1880 only risk is uglified messages. Please, run 'autoreconf -f -Wall'
1881 to find occurrences that will be affected.
1883 * Major changes in Autoconf 2.54
1885 Released 2002-09-13 by Akim Demaille.
1889 - autoreconf no longer changes the version of the gettext/po/intl
1890 support files. It now adds the files the correspond to the
1891 AM_GNU_GETTEXT_VERSION declared in configure.ac.
1893 Warning: It now relies on the 'autopoint' program, which is part
1894 of GNU gettext 0.11.4 and newer.
1896 Please note that you need to have a GNU gettext version that
1897 corresponds at least to the AM_GNU_GETTEXT_VERSION declared
1898 in configure.ac. You can upgrade to newer GNU gettext versions,
1899 though, without needing to change configure.ac.
1901 - The -I DIR or --include=DIR option now appends DIR to the include path
1902 instead of prepending; this is for consistency with other GNU tools.
1903 The new -B DIR or --prepend-include=DIR option has the old behavior.
1908 Now handles all the gory details about LIBOBJS and LTLIBOBJS.
1909 Please, remove lines such as
1911 # This is necessary so that .o files in LIBOBJS are also
1912 # built via the ANSI2KNR-filtering rules.
1913 LIBOBJS=`echo $LIBOBJS|sed 's/\.o /\$U.o /g;s/\.o$/\$U.o/'`
1915 and read the 'AC_LIBOBJ vs LIBOBJS' section. Do not define U in
1916 your Makefiles either.
1918 - AC_CONFIG_LINKS now makes copies if it can't make links.
1920 - AC_FUNC_FNMATCH now tests only for POSIX compatibility, reverting to
1921 Autoconf 2.13 behavior. The new macro AC_FUNC_FNMATCH_GNU also
1922 tests for GNU extensions to fnmatch, and replaces fnmatch if needed.
1924 - AC_FUNC_SETVBUF_REVERSED no longer fails when cross-compiling.
1926 - AC_PROG_CC_STDC is integrated into AC_PROG_CC.
1928 - AC_PROG_F77 default search no longer includes cf77 and cfg77.
1932 AC_C_BACKSLASH_A, AC_CONFIG_LIBOBJ_DIR, AC_GNU_SOURCE,
1933 AC_PROG_EGREP, AC_PROG_FGREP, AC_REPLACE_FNMATCH,
1934 AC_FUNC_FNMATCH_GNU, AC_FUNC_REALLOC, AC_TYPE_MBSTATE_T.
1936 - AC_FUNC_GETLOADAVG
1937 looks for getloadavg.c in the CONFIG_LIBOBJ_DIR.
1940 Now defines HAVE_MALLOC to 0 if 'malloc' does not work, and asks
1941 for an AC_LIBOBJ replacement.
1945 - Spurious complaints from 'm4_bmatch' about invalid regular
1946 expressions are suppressed.
1948 - Empty top_builddirs are properly handled.
1950 - AC_CHECK_MEMBER works correctly when the member is an aggregate.
1953 Now colon in the optional path arguments are properly handled.
1955 ** Improved portability
1957 - Both Autoconf the package, and the scripts it produces, should run
1958 more reliably with Zsh. Bear in mind it is the default Bourne shell
1961 - Autoconf and the scripts it produces no longer assume the existence of
1962 the obsolescent commands egrep and fgrep.
1966 - Limitations of Make
1970 The GNATS base moved to
1971 https://bugs.gnu.org/cgi-bin/gnatsweb.pl?database=autoconf
1972 (It is no longer available, though.)
1977 Now contains the list of output variables and files (AC_SUBST,
1980 * Major changes in Autoconf 2.53
1982 Released 2002-03-08 by Akim Demaille.
1986 Perl 5.005_03 or later is required: autom4te is written in Perl and is
1987 needed by autoconf. autoheader, autoreconf, ifnames, and autoscan are
1993 Argument requirements, output variables, defined macros.
1994 - M4sugar, M4sh, Autotest
1996 - Double quoting macros
1997 AC_TRY_CPP, AC_TRY_COMPILE, AC_TRY_LINK and AC_TRY_RUN.
1999 The Autoconf manual is now distributed under the terms of the GNU FDL.
2000 - Section 'Hosts and Cross-Compilation'
2001 Explains the rationale for the 2.5x changes in the cross-compilation
2002 chain, and in the relationships between build, host, and target
2004 Emphasizes that 'cross-compilation' == '--host is given'.
2005 If you are working on compilers etc., be sure to read this section.
2006 - Section 'AC_LIBOBJ vs. LIBOBJS'
2007 Explains why assigning LIBOBJS directly is now an error.
2008 Details how to update the code.
2013 Now used instead of hard coded line numbers.
2014 This eases the comparison of 'configure's, and diminishes the
2015 pressure over control version archives.
2016 Automatic replacement for shells that don't support this feature.
2017 - New output variables
2018 @builddir@, @top_builddir@, @abs_srcdir@, @abs_top_srcdir@, @abs_builddir@,
2023 Autoconf and Autotest modes are provided.
2028 New, used by the Autoconf suite to cache and speed up most processing.
2030 Supported by autom4te, autoconf and autoheader.
2032 Replaces --autoconf-dir and --localdir in autoconf, autoheader,
2033 autoupdate, and autoreconf.
2035 No longer passes --cygnus, --foreign, --gnits, --gnu, --include-deps:
2036 automake options are to be given via AUTOMAKE_OPTIONS.
2038 Runs gettextize and libtoolize when appropriate.
2040 --m4dir is no longer supported.
2042 Now runs only in the specified directories, defaulting to '.',
2043 but understands AC_CONFIG_SUBDIRS for dependent directories.
2044 Before, it used to run on all the 'configure.ac' found in the
2046 Independent packages are properly updated.
2050 - The top level $prefix is propagated to the AC_CONFIG_SUBDIRS configures.
2052 Under the user pressure, $? is finally available. Probably a mistake.
2053 - AC_F77_LIBRARY_LDFLAGS now supports the HP/UX f90 compiler.
2054 - Precious variables accumulation
2055 config.status could stack several copies of the precious variables
2057 - AC_PATH_PROG and family.
2058 Works properly when given a literal path.
2060 Somewhere since 2.13, the result had been reversed.
2064 - AC_C_BIGENDIAN supports the cross-compiling case.
2065 - AC_C_BIGENDIAN accepts ACTION-IF-TRUE, ACTION-IF-FALSE, and
2066 ACTION-IF-UNKNOWN arguments. All are optional, and the default
2067 for ACTION-IF-TRUE is to define WORDS_BIGENDIAN like AC_C_BIGENDIAN
2069 - AC_C_LONG_DOUBLE now succeeds only if 'long double' has more range or
2070 precision than 'double'.
2075 It now defines the preprocessor symbols PACKAGE_NAME,
2076 PACKAGE_TARNAME, PACKAGE_VERSION, PACKAGE_STRING, and
2080 Admits a fourth optional parameter: the tar name.
2082 - AC_CONFIG_COMMANDS, HEADERS, FILES, LINKS.
2083 Provide the user with srcdir, ac_srcdir, ac_top_srcdir, ac_builddir,
2084 ac_top_builddir, ac_abs_srcdir, ac_abs_top_srcdir, ac_abs_builddir,
2085 ac_abs_top_builddir.
2087 - AC_CONFIG_COMMANDS, HEADERS, FILES, LINKS and AC_OUTPUT.
2088 Are much less expensive when using long lists of files.
2091 Works with shell variables, and non alphanumeric names.
2095 - AC_FUNC_STRERROR_R now sets STRERROR_R_CHAR_P, not HAVE_WORKING_STRERROR_R,
2096 because POSIX 1003.1-200x draft 7 says strerror_r returns int, not char *.
2098 - AC_FUNC_STRTOD substitutes POW_LIB.
2103 * Major changes in Autoconf 2.52
2105 Released 2001-07-18 by Akim Demaille.
2110 This feature was present in autoconf 2.50 but was not documented.
2111 For example, '@<:@' is translated to '[' just before output. This
2112 is useful when writing strings that contain unbalanced quotes, or
2113 other hard-to-quote constructs.
2114 - m4_pattern_forbid, m4_pattern_allow
2115 - Tips for upgrading from 2.13.
2116 - Using autoscan to maintain a configure.ac.
2119 - Now include stdint.h.
2120 - sys/types.h and sys/stat.h are guarded.
2121 - strings.h is included if available, and not conflicting with string.h.
2124 - The test suite is more robust and presents less false failures.
2125 - Invocation of GNU M4 now robust to POSIXLY_CORRECT.
2126 - configure accepts --prefix='' again.
2127 - AC_CHECK_LIB works properly when its first argument is not a
2129 - HAVE_INTTYPES_H is defined only if not conflicting with sys/types.h.
2130 - build_, host_, and target_alias are AC_SUBST as in 2.13.
2131 - AC_ARG_VAR properly propagates precious variables inherited from the
2132 environment to ./config.status.
2133 - Using --program-suffix/--program-prefix is portable.
2134 - Failures to detect the default compiler's output extension are less
2136 - 'config.status foo' works properly when 'foo' depends on variables
2137 set in an AC_CONFIG_THING INIT-CMD.
2138 - autoheader is more robust to broken input.
2139 - Fixed Fortran name-mangling and link tests on a number of systems,
2140 e.g. NetBSD; see AC_F77_DUMMY_MAIN, below.
2143 - AC_CHECK_HEADER and AC_CHECK_HEADERS support a fourth argument to
2144 specify pre-includes. In this case, the headers are compiled with
2145 cc, not merely preprocessed by cpp. Therefore it is the _usability_
2146 of a header which is checked for, not just its availability.
2147 - AC_ARG_VAR refuses to run configure when precious variables have
2149 - Versions of compilers are dumped in the logs.
2150 - AC_CHECK_TYPE recognizes use of 'foo_t' as a replacement type.
2153 - AC_PATH_XTRA only adds -ldnet to $LIBS if it's needed to link.
2154 - AC_FUNC_WAIT3 and AC_SYS_RESTARTABLE_SYSCALLS are obsoleted.
2155 - AM_FUNC_ERROR_AT_LINE, AM_FUNC_FNMATCH, AM_FUNC_MKTIME,
2156 AM_FUNC_OBSTACK, and AM_FUNC_STRTOD are now activated.
2157 Be sure to read 'Upgrading from Version 2.13' to understand why
2158 running 'autoupdate' is needed.
2159 - AC_F77_DUMMY_MAIN, AC_F77_MAIN: new macros to detect whether
2160 a main-like routine is required/possible when linking C/C++ with
2161 Fortran. Users of e.g. AC_F77_WRAPPERS should be aware of these.
2162 - AC_FUNC_GETPGRP behaves better when cross-compiling.
2164 * Major changes in Autoconf 2.51
2165 There was no release of Autoconf 2.51 since some packagers had used
2166 this version number without permission to ship intermediary versions
2167 of 2.50. The version was skipped to avoid confusion.
2169 * Major changes in Autoconf 2.50
2171 Released 2001-05-21 by Akim Demaille.
2173 ** Lots of bug fixes
2174 There have been far too many to enumerate them here. Check out
2175 ChangeLog if you really want to know more.
2177 ** Improved documentation
2178 In particular, portability issues are better covered.
2181 All the standard GNU Makefile targets are supported. The layout has
2182 changed: m4/ holds the M4 extensions Autoconf needs for its
2183 configuration, doc/ contains the documentation, and tests/ contains
2186 ** Man pages are provided
2187 For autoconf, autoreconf, autoupdate, autoheader, autoscan, ifnames,
2188 config.guess, config.sub.
2192 Provides a safe and powerful means to trace the macro uses. This
2193 provide the parsing layer for tools which need to 'study'
2197 Specify what category of warnings should be enabled.
2199 - When recursing into subdirectories, try for configure.gnu before
2200 configure to adapt for packages not using autoconf on case-insensitive
2204 More errors are now caught (circular AC_REQUIRE dependencies,
2205 AC_DEFINE in the action part of an AC_CACHE_CHECK, too many pops
2206 etc.). In addition, their location and call stack are given.
2209 autoupdate is much more powerful, and is able to provide the glue code
2210 which might be needed to move from an old macro to its newer
2213 You are strongly encouraged to use it to modernize both your
2214 'configure.in' and your .m4 extension files.
2217 The internal machinery of autoheader has completely changed. As a
2218 result, using 'acconfig.h' should be considered to be obsoleted, and
2219 you are encouraged to get rid of it using the AH macros.
2224 ** Fortran 77 compilers
2225 Globally, the support for Fortran 77 is considerably improved.
2227 Support for automatically determining a Fortran 77 compiler's
2228 name-mangling scheme. New CPP macros F77_FUNC and F77_FUNC_ are
2229 provided to wrap C/C++ identifiers, thus making it easier and more
2230 transparent for C/C++ to call Fortran 77 routines, and Fortran 77 to
2231 call C/C++ routines. See the Texinfo documentation for details.
2234 The test suite no longer uses DejaGNU. It should be easy to submit
2235 test cases in this new framework.
2238 - --help, --help=long, -hl
2239 no longer dumps useless items.
2241 lists only specific options.
2242 - --help=recursive, -hr
2243 displays the help of all the embedded packages.
2244 - Remembers environment variables when reconfiguring.
2245 The previous scheme to set envvar before running configure was
2247 what prevented configure from remembering the environment in which
2248 it was run, therefore --recheck was run in an inconsistent
2249 environment. Now, one should run
2251 and then --recheck will work properly. Variables declared with
2252 AC_ARG_VAR are also preserved.
2254 $build defaults to `config.guess`, $host to $build, and then $target
2256 Cross-compilation is a global status of the package, it no longer
2257 depends upon the current language.
2258 Cross compilation is enabled iff the user specified '--host'.
2259 'configure' now fails if it can't run the executables it compiles,
2260 unless cross-compilation is enabled.
2262 The cache file is disabled by default. The new options
2263 '--config-cache', '-C' set the cache to 'config.cache'.
2267 Much faster on most architectures.
2268 - concurrent executions
2269 It is safe to use 'make -j' with config.status.
2270 - human interface improved
2271 It is possible to invoke
2272 ./config.status foobar
2273 instead of the former form (still valid)
2274 CONFIG_COMMANDS= CONFIG_HEADERS= CONFIG_LINKS= \
2275 CONFIG_FILES=foobar:foo.in:bar.in \
2277 The same holds for configuration headers and links.
2278 You can instantiate unknown files and headers:
2279 ./config.status --header foo.h:foo.h.in --file bar:baz
2280 - has a useful --help
2281 - accepts special file name "-" for stdin/stdout
2286 Specify additional copyright information.
2289 Now expects the identity of the package as argument.
2293 Most macros, if not all, now strictly follow the 'one quotation
2294 level' rule. This results in a more predictable expansion.
2297 A sly bug in the AC_REQUIRE machinery, which could produce incorrect
2298 configure scripts, was fixed by Axel Thimm.
2302 Document and ask for the registration of an envvar.
2305 Specifies the file which 'configure' should look for when trying to
2306 find the source tree (used to be handled by AC_INIT).
2308 - AC_CONFIG_COMMANDS
2309 To add new actions to config.status. Should be used instead of
2313 Replaces AC_LINK_FILES.
2315 - AC_CONFIG_HEADERS, AC_CONFIG_COMMANDS, AC_CONFIG_SUBDIRS,
2316 AC_CONFIG_LINKS, and AC_CONFIG_FILES
2317 They now obey sh: you should no longer use shell variables as
2318 argument. Instead of
2320 test "$package_foo_enabled" = yes && $my_subdirs="$my_subdirs foo"
2321 AC_CONFIG_SUBDIRS($my_subdirs)
2325 if test "$package_foo_enabled" = yes; then
2326 AC_CONFIG_SUBDIRS(foo)
2330 To format an Autoconf macro's help string so that it looks pretty
2331 when the user executes 'configure --help'.
2334 ** Generic Test Macros
2336 The interface of the AC_CHECK families of macros (decl, header,
2337 type, member, func) is now uniform. They support the same set of
2340 - AC_CHECK_DECL, AC_CHECK_DECLS
2341 To check whether a symbol is declared.
2343 - AC_CHECK_SIZEOF, AC_C_CHAR_UNSIGNED.
2344 No longer need a cross-compilation default.
2347 The test it performs is much more robust than previously, and makes
2348 it possible to test builtin types in addition to typedefs.
2349 It is now schizophrenic:
2350 - AC_CHECK_TYPE(TYPE, REPLACEMENT)
2351 remains for backward compatibility, but its use is discouraged.
2352 - AC_CHECK_TYPE(TYPE, IF-FOUND, IF-NOT-FOUND, INCLUDES)
2353 behaves exactly like the other AC_CHECK macros.
2356 Checks whether given types are supported by the system.
2358 - AC_CHECK_MEMBER, AC_CHECK_MEMBERS
2359 Check for given members in aggregates (e.g., pw_gecos in struct
2363 Checks if the compiler supports ISO C, included when needs special
2367 Checking whether the preprocessor indicates missing includes by the
2368 error code. stderr is checked by AC_TRY_CPP only as a fallback.
2371 Takes a language as argument and replaces AC_LANG_C,
2372 AC_LANG_CPLUSPLUS and AC_LANG_FORTRAN77.
2374 - AC_LANG_PUSH, AC_LANG_POP
2375 Are preferred to AC_LANG_SAVE, AC_LANG_RESTORE.
2378 - AC_FUNC_CHOWN, AC_FUNC_MALLOC, AC_FUNC_STRERROR_R,
2379 AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK, AC_FUNC_STAT, AC_FUNC_LSTAT,
2380 AC_FUNC_ERROR_AT_LINE, AC_FUNC_OBSTACK, AC_FUNC_STRTOD, AC_FUNC_FSEEKO.
2384 Sets GETGROUPS_LIBS.
2386 - AC_FUNC_GETLOADAVG
2387 Defines 'HAVE_STRUCT_NLIST_N_UN_N_NAME' instead of 'NLIST_NAME_UNION'.
2390 Now integrates 'AC_DECL_YYTEXT' which is obsoleted.
2393 Arrange for large-file support.
2395 - AC_EXEEXT, AC_OBJEXT
2396 You are no longer expected to use them: their computation is
2397 performed by default.
2399 ** C++ compatibility
2400 Every macro has been revisited in order to support at best CC=c++.
2402 Major changes in Autoconf 2.14:
2403 There was no release of GNU Autoconf 2.14.
2405 Major changes in Autoconf 2.13:
2407 Released 1999-05-01 by Ben Elliston.
2409 * Support for building on 32-bit Windows systems where the only available C or
2410 C++ compiler is the Microsoft Visual C++ command line compiler
2411 ('cl'). Additional support for building on 32-bit Windows systems which are
2412 using the Cygwin or Mingw32 environments.
2413 * Support for alternative object file and executable file extensions.
2414 On 32-bit Windows, for example, these are .obj and .exe. These are discovered
2415 using AC_OBJEXT and AC_EXEEXT, which substitute @OBJEXT@ and
2416 @EXEEXT@ in the output, respectively.
2417 * New macros: AC_CACHE_LOAD, AC_CACHE_SAVE, AC_FUNC_SELECT_ARGTYPES,
2418 AC_VALIDATE_CACHED_SYSTEM_TUPLE, AC_SEARCH_LIBS, AC_TRY_LINK_FUNC,
2419 AC_C_STRINGIZE, AC_CHECK_FILE(S), AC_PROG_F77 (and friends).
2420 * AC_DEFINE now has an optional third argument for a description to be
2421 placed in the config header input file (e.g. config.h.in).
2422 * The C++ code fragment compiled for the C++ compiler test had to be
2423 improved to include an explicit return type for main(). This was
2424 causing failures on systems using recent versions of the EGCS C++
2426 * Fixed an important bug in AC_CHECK_TYPE that would cause a configure
2427 script to report that 'sometype_t' was present when only 'type_t'
2429 * Merge of the FSF version of config.guess and config.sub to modernize
2430 these scripts. Add support for a few new hosts in config.guess.
2431 Incorporate latest versions of install-sh, mkinstalldirs and
2432 texinfo.tex from the FSF.
2433 * autoreconf is capable of running automake if necessary (and
2435 * Support for Fortran 77. See the Texinfo documentation for details.
2436 * Bug fixes and workarounds for quirky bugs in vendor utilities.
2438 Major changes in Autoconf 2.12:
2440 Released 1996-11-26 by David J. MacKenzie
2442 * AC_OUTPUT and AC_CONFIG_HEADERS can create output files by
2443 concatenating multiple input files separated by colons, like so:
2444 AC_CONFIG_HEADERS([config.h:conf.pre:config.h.in:conf.post])
2445 AC_OUTPUT([Makefile:Makefile.in:Makefile.rules])
2446 The arguments may be shell variables, to compute the lists on the fly.
2447 * AC_LINK_FILES and AC_CONFIG_SUBDIRS may be called multiple times.
2448 * New macro AC_OUTPUT_COMMANDS adds more commands to run in config.status.
2451 Major changes in Autoconf 2.11:
2453 Released November 18th, 1996, by David J. MacKenzie
2455 * AC_PROG_CC and AC_PROG_CXX check whether the compiler works.
2456 They also default CFLAGS/CXXFLAGS to "-g -O2" for gcc, instead of "-g -O".
2457 * AC_REPLACE_FUNCS defines HAVE_foo if the system has the function 'foo'.
2458 * AC_CONFIG_HEADERS expands shell variables in its argument.
2459 * New macros: AC_FUNC_FNMATCH, AC_FUNC_SETPGRP.
2460 * The "checking..." messages and the source code for test programs that
2461 fail are saved in config.log.
2462 * Another workaround has been added for seds with small command length limits.
2463 * config.sub and config.guess recognize more system types.
2466 Major changes in Autoconf 2.10:
2468 Released May 7th, 1996, by Roland McGrath
2471 * The cache variable names used by 'AC_CHECK_LIB(LIB, FUNC, ...)' has
2472 changed: now $ac_cv_lib_LIB_FUNC, previously $ac_cv_lib_LIB.
2474 Major changes in Autoconf 2.9:
2476 Released March 16th, 1996, by Roland McGrath
2480 Major changes in Autoconf 2.8:
2482 Released March 8th, 1996, by Roland McGrath
2486 Major changes in Autoconf 2.7:
2488 Released November 22nd, 1995, by David J. MacKenzie
2492 Major changes in Autoconf 2.6:
2494 Released November 20th, 1995, by David J. MacKenzie
2498 Major changes in Autoconf 2.5:
2500 Released November 17th, 1995, by Roland McGrath
2502 * New configure options --bindir, --libdir, --datadir, etc., with
2503 corresponding output variables.
2504 * New macro: AC_CACHE_CHECK, to make using the cache easier.
2505 * config.log contains the command being run as well as any output from it.
2506 * AC_CHECK_LIB can check for libraries with "." or "/" or "+" in their name.
2507 * AC_PROG_INSTALL doesn't cache a name for install-sh, for sharing caches.
2508 * AC_CHECK_PROG, AC_PATH_PROG, AC_CHECK_PROGS, AC_PATH_PROGS, and
2509 AC_CHECK_TOOL can search a path other than $PATH.
2510 * AC_CHECK_SIZEOF takes an optional size to use when cross-compiling.
2512 Major changes in Autoconf 2.4:
2514 Released June 14th, 1995, by David J. MacKenzie
2516 * Fix a few bugs found by Emacs testers.
2518 Major changes in Autoconf 2.3:
2520 Released March 27th, 1995, by David J. MacKenzie
2522 * Fix the cleanup trap in several ways.
2523 * Handle C compilers that are picky about option placement.
2524 * ifnames gets the version number from the right directory.
2526 Major changes in Autoconf 2.2:
2528 Released March 8th, 1995, by David J. MacKenzie
2530 * The ifnames utility is much faster but requires a "new awk" interpreter.
2531 * AC_CHECK_LIB and AC_HAVE_LIBRARY check and add the new
2532 library before existing libs, not after, in case it uses them.
2533 * New macros: AC_FUNC_GETPGRP, AC_CHECK_TOOL.
2534 * Lots of bug fixes.
2535 * Many additions to the TODO file :-)
2537 Major changes in Autoconf 2.1:
2539 Released November 4th, 1994, by David J. MacKenzie
2542 * More explanations in the manual.
2543 * Fix a spurious failure in the testsuite.
2544 * Clarify some warning messages.
2545 * autoreconf by default only rebuilds configure and config.h.in files
2546 that are older than any of their particular input files; there is a
2547 --force option to use after installing a new version of Autoconf.
2549 Thanks to everybody who's submitted changes and additions to Autoconf!
2550 I've incorporated many of them, and am still considering others for
2551 future releases -- but I didn't want to postpone this release indefinitely.
2553 Caution: don't indiscriminately rebuild configure scripts with
2554 Autoconf version 2. Some configure.in files need minor adjustments to
2555 work with it; the documentation has a chapter on upgrading. A few
2556 configure.in files, including those for GNU Emacs and the GNU C
2557 Library, need major changes because they relied on undocumented
2558 internals of version 1. Future releases of those packages will have
2559 updated configure.in files.
2561 It's best to use GNU M4 1.3 (or later) with Autoconf version 2.
2562 Autoconf now makes heavy use of M4 diversions, which were implemented
2563 inefficiently in GNU M4 releases before 1.3.
2565 Major changes in Autoconf 2.0:
2567 Released October 26th, 1994, by David J. MacKenzie
2569 ** New copyright terms:
2570 * There are no restrictions on distribution or use of configure scripts.
2573 * Autoconf manual is reorganized to make information easier to find
2574 and has several new indexes.
2575 * INSTALL is reorganized and clearer and is now made from Texinfo source.
2578 * autoscan to generate a preliminary configure.in for a package by
2579 scanning its source code for commonly used nonportable functions,
2580 programs, and header files.
2581 * ifnames to list the symbols used in #if and #ifdef directives in a
2583 * autoupdate to update a configure.in to use the version 2 macro names.
2584 * autoreconf to recursively remake configure and configuration header
2585 files in a source tree.
2587 ** Changed utilities:
2588 * autoheader can take pieces of acconfig.h to replace config.h.{top,bot}.
2589 * autoconf and autoheader can look for package-local definition files
2590 in an alternate directory.
2593 * AC_CACHE_VAL to share results of tests between configure runs.
2594 * AC_DEFUN to define macros, automatically AC_PROVIDE them, and ensure
2595 that macros invoked with AC_REQUIRE don't interrupt other macros.
2596 * AC_CONFIG_AUX_DIR, AC_CANONICAL_SYSTEM, AC_CANONICAL_HOST, AC_LINK_FILES to
2597 support deciding unguessable features based on the host and target types.
2598 * AC_CONFIG_SUBDIRS to recursively configure a source tree.
2599 * AC_ARG_PROGRAM to use the options --program-prefix,
2600 --program-suffix, and --program-transform-name to change the names
2601 of programs being installed.
2602 * AC_PREFIX_DEFAULT to change the default installation prefix.
2603 * AC_TRY_COMPILE to compile a test program without linking it.
2604 * AC_CHECK_TYPE to check whether sys/types.h or stdlib.h defines a given type.
2605 * AC_CHECK_LIB to check for a particular function and library.
2606 * AC_MSG_CHECKING and AC_MSG_RESULT to print test results, on a single line,
2607 whether or not the test succeeds. They obsolete AC_CHECKING and AC_VERBOSE.
2608 * AC_SUBST_FILE to insert one file into another.
2609 * AC_FUNC_MEMCMP to check whether memcmp is 8-bit clean.
2610 * AC_FUNC_STRFTIME to find strftime even if it's in -lintl.
2611 * AC_FUNC_GETMNTENT to find getmntent even if it's in -lsun or -lseq.
2612 * AC_HEADER_SYS_WAIT to check whether sys/wait.h is POSIX.1 compatible.
2615 * Many macros renamed systematically, but old names are accepted for
2616 backward compatibility.
2617 * AC_OUTPUT adds the "automatically generated" comment to
2618 non-Makefiles where it finds @configure_input@ in an input file, to
2619 support files with various comment syntaxes.
2620 * AC_OUTPUT does not replace "prefix" and "exec_prefix" in generated
2621 files when they are not enclosed in @ signs.
2622 * AC_OUTPUT allows the optional environment variable CONFIG_STATUS to
2623 override the file name "config.status".
2624 * AC_OUTPUT takes an optional argument for passing variables from
2625 configure to config.status.
2626 * AC_OUTPUT and AC_CONFIG_HEADERS allow you to override the input-file names.
2627 * AC_OUTPUT automatically substitutes the values of CFLAGS, CXXFLAGS,
2628 CPPFLAGS, and LDFLAGS from the environment.
2629 * AC_PROG_CC and AC_PROG_CXX now set CFLAGS and CXXFLAGS, respectively.
2630 * AC_PROG_INSTALL looks for install-sh or install.sh in the directory
2631 specified by AC_CONFIG_AUXDIR, or srcdir or srcdir/.. or
2632 srcdir/../.. by default.
2633 * AC_DEFINE, AC_DEFINE_UNQUOTED, and AC_SUBST are more robust and smaller.
2634 * AC_DEFINE no longer prints anything, because of the new result reporting
2635 mechanism (AC_MSG_CHECKING and AC_MSG_RESULT).
2636 * AC_VERBOSE pays attention to --quiet/--silent, not --verbose.
2637 * AC_ARG_ENABLE and AC_ARG_WITH support whitespace in the arguments to
2638 --enable- and --with- options.
2639 * AC_CHECK_FUNCS and AC_CHECK_HEADERS take optional shell commands to
2640 execute on success or failure.
2641 * Checking for C functions in C++ works.
2644 * AC_REMOTE_TAPE and AC_RSH removed; too specific to tar and cpio, and
2645 better maintained with them.
2646 * AC_ARG_ARRAY removed because no one was likely using it.
2647 * AC_HAVE_POUNDBANG replaced with AC_SYS_INTERPRETER, which doesn't
2648 take arguments, for consistency with all of the other specific checks.
2651 * Comes with config.sub and config.guess, and uses them optionally.
2652 * Uses config.cache to cache test results. An alternate cache file
2653 can be selected with the --cache-file=FILE option.
2654 * Uses optional shell scripts $prefix/share/config.site and
2655 $prefix/etc/config.site to perform site or system specific initializations.
2656 * configure saves compiler output to ./config.log for debugging.
2657 * New files autoconf.m4 and autoheader.m4 load the other Autoconf macros.
2658 * acsite.m4 is the new name for the system-wide aclocal.m4.
2659 * Has a DejaGnu test suite.
2661 Major changes in Autoconf 1.11:
2663 * AC_PROG_INSTALL calls install.sh with the -c option.
2664 * AC_SET_MAKE cleans up after itself.
2665 * AC_OUTPUT sets prefix and exec_prefix if they weren't set already.
2666 * AC_OUTPUT prevents shells from looking in PATH for config.status.
2668 Plus a few other bug fixes.
2670 Major changes in Autoconf 1.10:
2672 * autoheader uses config.h.bot if present, analogous to config.h.top.
2673 * AC_PROG_INSTALL looks for install.sh in srcdir or srcdir/.. and
2675 * AC_PROG_CXX looks for cxx as a C++ compiler.
2677 Plus several bugs fixed.
2679 Major changes in Autoconf 1.9:
2681 * AC_YYTEXT_POINTER replaces AC_DECLARE_YYTEXT.
2682 * AC_SIZEOF_TYPE generates the cpp symbol name automatically,
2683 and autoheader generates entries for those names automatically.
2684 * AC_FIND_X gets the result from xmkmf correctly.
2685 * AC_FIND_X assumes no X if --without-x was given.
2686 * AC_FIND_XTRA adds libraries to the variable X_EXTRA_LIBS.
2687 * AC_PROG_INSTALL finds OSF/1 installbsd.
2689 Major changes in Autoconf 1.8:
2692 * New macros AC_LANG_C, AC_LANG_CPLUSPLUS, AC_LANG_SAVE, AC_LANG_RESTORE,
2693 AC_PROG_CXX, AC_PROG_CXXCPP, AC_REQUIRE_CPP
2694 for checking both C++ and C features in one configure script.
2695 * New macros AC_CHECKING, AC_VERBOSE, AC_WARN, AC_ERROR for printing messages.
2696 * New macros AC_FIND_XTRA, AC_MMAP, AC_SIZEOF_TYPE, AC_PREREQ,
2697 AC_SET_MAKE, AC_ENABLE.
2700 * AC_FIND_X looks for X in more places.
2701 * AC_PROG_INSTALL defaults to install.sh instead of cp, if it's in srcdir.
2702 install.sh is distributed with Autoconf.
2703 * AC_DECLARE_YYTEXT has been removed because it can't work, pending
2704 a rewrite of quoting in AC_DEFINE.
2705 * AC_OUTPUT adds its comments in C format when substituting in C files.
2706 * AC_COMPILE_CHECK protects its ECHO-TEXT argument with double quotes.
2708 ** New or changed command line options:
2709 * configure accepts --enable-FEATURE[=ARG] and --disable-FEATURE options.
2710 * configure accepts --without-PACKAGE, which sets withval=no.
2711 * configure accepts --x-includes=DIR and --x-libraries=DIR.
2712 * Giving --with-PACKAGE no argument sets withval=yes instead of withval=1.
2713 * configure accepts --help, --version, --silent/--quiet, --no-create options.
2714 * configure accepts and ignores most other Cygnus configure options, and
2715 warns about unknown options.
2716 * config.status accepts --help, --version options.
2718 ** File names and other changes:
2719 * Relative srcdir values are not made absolute.
2720 * The values of @prefix@ and @exec_prefix@ and @top_srcdir@ get substituted.
2721 * Autoconf library files are installed in ${datadir}/autoconf, not ${datadir}.
2722 * autoheader optionally copies config.h.top to the beginning of config.h.in.
2723 * The example Makefile dependencies for configure et al. work better.
2724 * Namespace cleanup: all shell variables used internally by Autoconf
2725 have names beginning with 'ac_'.
2727 More big improvements are in process for future releases, but have not
2728 yet been (variously) finished, integrated, tested, or documented enough
2731 Major changes in Autoconf 1.7:
2733 * New macro AC_OBSOLETE.
2734 * Bugs in Makefile.in fixed.
2735 * AC_LONG_FILE_NAMES improved.
2737 Major changes in Autoconf 1.6:
2739 * New macro AC_LONG_64_BITS.
2740 * Multiple .h files can be created.
2741 * AC_FIND_X looks for X files directly if it doesn't find xmkmf.
2742 * AC_ALLOCA defines C_ALLOCA if using alloca.c.
2743 * --with-NAME can take a value, e.g., --with-targets=sun4,hp300bsd.
2744 * Unused --no-create option to configure removed.
2745 * autoheader doesn't change the timestamp of its output file if
2746 the file didn't change.
2747 * All macros that look for libraries now use AC_HAVE_LIBRARY.
2748 * config.status checks three optional environment variables to
2749 modify its behavior.
2750 * The usual bug fixes.
2752 Major changes in Autoconf 1.5:
2754 * New macros AC_FIND_X, AC_OFF_T, AC_STAT_MACROS_BROKEN, AC_REVISION.
2755 * autoconf and autoheader scripts have GNU standards conforming
2756 --version and --help options (they print their message and exit).
2759 Major changes in Autoconf 1.4:
2761 * New macros AC_HAVE_POUNDBANG, AC_TIME_WITH_SYS_TIME, AC_LONG_DOUBLE,
2762 AC_GETGROUPS_T, AC_DEFINE_UNQUOTED.
2763 * autoconf and autoheader use the M4 environment variable to determine the
2764 name of the M4 program to use.
2765 * The --macrodir option to autoconf and autoheader specifies the directory
2766 in which acspecific.m4, acgeneral.m4, etc. reside if not the default.
2767 * autoconf and autoheader can take '-' as their file names, which means to
2768 read stdin as input.
2769 * Resulting configure scripts can take a --verbose option which causes them
2770 to print the results of their tests.
2771 * AC_DEFINE quotes its second argument in such a way that spaces, magic
2772 shell characters, etc. will be preserved during various stages of
2773 expansion done by the shell. If you don't want this, use
2774 AC_DEFINE_UNQUOTED instead.
2775 * Much textual processing done with external calls to tr and sed have been
2776 internalized with builtin M4 'patsubst' and 'translit' calls.
2777 * AC_OUTPUT doesn't hardwire the file names it outputs. Instead, you can
2778 set the shell variables 'gen_files' and 'gen_config' to the list of
2779 file names to output.
2780 * AC_DECLARE_YYTEXT does an AC_SUBST of 'LEX_OUTPUT_ROOT', which may be
2781 "lex.yy" or "lexyy", depending on the system.
2782 * AC_PROGRAMS_CHECK takes an optional third arg. If given, it is used as
2784 * If AC_ALLOCA chooses alloca.c, it also defines STACK_DIRECTION.
2785 * AC_CONST works much more reliably on more systems.
2788 Major changes in Autoconf 1.3:
2790 configure no longer requires awk for packages that use a config.h.
2791 Support handling --with-PACKAGE options.
2792 New 'autoheader' script to create 'config.h.in' from 'configure.in'.
2793 Ignore troublesome -lucb and -lPW when searching for alloca.
2794 Rename --exec_prefix to --exec-prefix for GNU standards conformance.
2795 Improve detection of STDC library.
2796 Add AC_HAVE_LIBRARY to check for non-default libraries.
2797 Function checking should work with future GNU libc releases.
2799 Major changes in Autoconf 1.2:
2801 The --srcdir option is now usually unnecessary.
2802 Add a file containing sample comments describing CPP macros.
2803 A comment in config.status tells which host it was configured on.
2804 Substituted variable values can now contain commas.
2805 Fix bugs in various feature checks.
2807 Major changes in Autoconf 1.1:
2809 Added AC_STRCOLL macro.
2810 Made AC_GETLOADAVG check for more things.
2811 AC_OUTPUT argument is now optional.
2816 Copyright (C) 1993-1996, 1998-2017, 2020-2024 Free Software Foundation,
2819 Copying and distribution of this file, with or without modification,
2820 are permitted in any medium without royalty provided the copyright
2821 notice and this notice are preserved. This file is offered as-is,
2822 without warranty of any kind.