1 GNU Autoconf NEWS - User visible changes.
3 * Noteworthy changes in release ?.? (????-??-??) [?]
5 ** Backward incompatibilities
7 *** Autoconf now requires perl 5.10 (2007) or later.
8 Generated 'configure' scripts continue to run without perl.
10 *** Autoconf now requires GNU M4 1.4.8 (2006) or later.
11 Generated 'configure' scripts continue to run without M4.
13 Use of GNU M4 1.4.16 or later is recommended, as all earlier versions
14 are known to have had serious bugs in the text-processing builtins
15 on some, but not all, operating systems. Autoconf’s own configure
16 script will attempt to find a version of M4 that is not affected by
19 Note: Autoconf 2.70 and 2.71 include code that malfunctions with
20 M4 1.4.6 or 1.4.7. However, the only effect of the malfunction is
21 that you will get a confusing error message if you run autoconf on
22 a configure.ac that neglects to use AC_INIT or AC_OUTPUT.
24 *** m4sh diversions like BINSH have been renumbered.
25 This matters only for uses that, contrary to the documentation
26 and despite warnings, use m4_divert with numbered diversions.
30 *** New macro AC_SYS_YEAR2038.
31 This causes 'configure' to widen time_t if possible on systems where
32 time_t by default cannot represent file and other timestamps after
33 January 2038. Widening is possible only on 32-bit GNU/Linux x86 and
34 ARM systems with glibc 2.34 or later. To prevent widening,
35 configure with --disable-year2038.
37 This macro also has the effects as AC_SYS_LARGEFILE, because in
38 practice time_t cannot be widened without large-file sypport.
40 Application and library builders should take care that packages
41 configured with --enable-year2038 and --disable-year2038 options
42 are configured consistently, to avoid breaking binary compatibility.
43 This is similar to longstanding consistency requirements with
44 --enable-largefile and --disable-largefile.
46 *** AC_SYS_LARGEFILE now optionally arranges to widen time_t.
47 It now acts like AC_SYS_YEAR2038, except 'configure' defaults to
48 --disable-year2038 unless AC_SYS_YEAR2038 is also present.
49 As with AC_SYS_YEAR2038, application and library builders should
50 configure consistently.
52 *** New macros AC_SYS_LARGEFILE_REQUIRED and AC_SYS_YEAR2038_REQUIRED.
53 These act like AC_SYS_LARGEFILE and AC_SYS_YEAR2038 respectively,
54 except that 'configure' fails if the target lacks support
55 for large files and for post-2038 timestamps, respectively.
56 As with AC_SYS_YEAR2038, application and library builders should
57 configure consistently.
59 *** AC_USE_SYSTEM_EXTENSIONS now enables C23 Annex F extensions
60 by defining __STDC_WANT_IEC_60559_EXT__.
62 ** Obsolete features and new warnings
64 *** Autoconf now quotes 'like this' instead of `like this'.
66 Autoconf’s diagnostics now follow current GNU coding standards,
67 which say that diagnostics in the C locale should quote 'like this'
68 with plain apostrophes instead of the older GNU style `like this'
69 with grave accent and apostrophe.
73 *** Autoconf caches now use finer-grained timestamps.
75 Autoconf now uses floating-point numbers rather than integers to
76 represent cache file timestamps, thus avoiding some problems where
77 automake incorrectly decides not to regenerate stale caches.
79 *** AC_HEADER_STDBOOL, AC_CHECK_HEADER_STDBOOL are obsolescent and less picky.
81 These macros are now obsolescent, as programs can simply include
82 stdbool.h unconditionally. If you use these macros, they now accept
83 a stdbool.h that exists but does nothing, so long as ‘bool’, ‘true’,
84 and ‘false’ work anyway. This is for compatibility with C23 and
87 *** AC_PROG_MKDIR_P now falls back on plain 'mkdir -p'.
89 When AC_PROG_MKDIR_P cannot find a mkdir implementation that is
90 known to lack race condition bugs, it now falls back on 'mkdir -p'
91 instead of falling back on a relative path to install-sh, as the
92 relative paths now seem to be a more important problem than the
93 problems of ancient mkdir implementations with race condition bugs.
94 See <https://savannah.gnu.org/support/?110740>. The only ancient
95 mkdir still supported is Solaris 10 /usr/bin/mkdir, and for that
96 platform AC_PROG_MKDIR_P falls back on /opt/sfw/bin/mkdir which
97 should work if it is installed; if not, you should avoid parallel
98 'make' on that platform.
100 * Noteworthy changes in release 2.71 (2021-01-28) [stable]
102 ** Bug fixes, including:
104 *** Compilers that support C99 but not C2011 are detected correctly.
106 *** Compatibility improved with clang and Oracle C++.
108 *** Compatibility restored with automake's rules for regenerating configure.
110 *** Compatibility restored with old versions of std-gnu11.m4.
112 Packages that wish to maintain compatibility with Autoconf 2.69 or
113 older, should update their copy of std-gnu11.m4 from Gnulib as soon
114 as practical, as the compatibility code bulks up the configure script.
116 Packages that require Autoconf 2.70 can drop this file entirely.
118 * Noteworthy changes in release 2.70 (2020-12-08) [stable]
120 ** Backward incompatibilities:
122 *** Warnings about obsolete constructs are now on by default.
124 These warnings can be turned off with ‘-Wno-obsolete’.
126 Many of these warnings advise maintainers to run autoupdate.
127 Be aware that autoupdate cannot solve all backward compatibility
128 problems, and cannot completely solve all of the problems it does
129 address. A configure script edited by autoupdate is likely to
130 need further manual fix-ups.
132 *** Many macros have become pickier about argument quotation.
134 If you get a shell syntax error from your generated configure
135 script, or seemingly impossible misbehavior (e.g. entire blocks of
136 the configure script not getting executed), check first that all
137 macro arguments are properly quoted. The “M4 Quotation” section of
138 the manual explains how to quote macro arguments properly.
140 It is unfortunately not possible for autoupdate to correct
143 *** Many macros no longer AC_REQUIRE as many other macros as they used to.
145 This can expose several classes of latent bugs. These are the ones
148 - Make sure to explicitly invoke all of the macros that set result
149 variables used later in the configure script, or in generated
152 - Autoconf macros that use AC_REQUIRE are not safe to use in shell
153 control-flow constructs that appear outside of macros defined by
154 AC_DEFUN. Use AS_IF, AS_CASE, etc. instead. (See the
155 “Prerequisite Macros” section of the manual for details.)
157 The set of macros that use AC_REQUIRE internally may change from
158 release to release. The only macros that are guaranteed *not* to
159 use AC_REQUIRE are the macros for acting on the results of a
160 test: AC_DEFINE, AC_SUBST, AC_MSG_*, AC_CACHE_CHECK, etc.
162 - AC_REQUIRE cannot be applied to macros that need to be used with
163 arguments. Instead, invoke the macro normally, with its arguments.
165 *** More macros use config.sub and config.guess internally.
167 As a consequence of improved support for cross compilation (see below),
168 more macros now use the auxiliary scripts ‘config.sub’ and ‘config.guess’.
169 If you use any of the affected macros, these scripts must be available
170 when your configure script is run, even if you have no intention of
171 ever cross-compiling your program.
173 autoreconf will issue an error if any auxiliary scripts are needed but
174 cannot be found. (It is not currently possible to make autoconf
175 itself issue this error.)
177 ‘autoreconf --install’ will add ‘config.sub’, ‘config.guess’, and
178 ‘install-sh’ to your source tree if they are needed. If you are
179 using Automake, scripts added to your tree by ‘autoreconf --install’
180 will automatically be included in the tarball produced by ‘make dist’;
181 otherwise, you will need to arrange for them to be distributed
184 See the “Input” section of the manual for more detail, including
185 where to get the auxiliary scripts that may be needed by autoconf macros.
187 *** Setting CC to a C++ compiler is no longer supported.
189 The C and C++ languages have diverged enough that we can no longer
190 guarantee that test C programs will be processed as intended by a
191 C++ compiler. In this release, configure will proceed anyway, but
192 many test results will be incorrect. In a future release, we may
193 make AC_PROG_CC error out if it detects that CC is a C++ compiler.
195 See the “Language Choice” section of the manual for instructions on
196 how to write configure scripts for C++ programs, and for programs
197 with code in more than one language.
199 *** Running configure tests with warnings promoted to errors is not supported.
201 For instance, setting ‘CC="gcc -Werror"’ on the configure command
202 line, or adding -Werror to CFLAGS early in the configure script when
203 the compiler recognizes this option, is very likely to cause
204 subsequent tests to fail.
206 This has never been guaranteed to work; the code generated by
207 AC_CHECK_FUNC, for instance, is incorrect by a strict reading of the
208 original 1989 C standard, and has been ever since that macro was
209 introduced. Problems are more likely with newer, pickier compilers.
211 To enable compiler warnings and/or warnings-as-errors mode for your
212 own code, we currently recommend a dedicated Makefile variable
213 (e.g. ‘WARN_CFLAGS’) that is set by AC_SUBST when appropriate.
214 The Gnulib ‘warnings’ and ‘manywarnings’ modules can help with this.
215 We plan to add core support for probing for useful sets of compiler
216 warnings in a future release.
218 *** Including confdefs.h manually may cause test failures.
220 This has never been necessary; confdefs.h is automatically included
221 at the beginning of all test programs (by AC_LANG_SOURCE). Because
222 of the way confdefs.h is generated and used, it is not practical to
223 give it a multiple inclusion guard. Therefore, if you include it
224 yourself, all of its definitions will be scanned twice.
226 Historically this has not been a problem, because confdefs.h only
227 makes macro definitions, and the C standard allows redefinitions
228 of macros as long as they’re exactly the same, but newer, pickier
229 compilers may complain anyway (see for instance GCC bug 97998).
231 *** Older versions of automake and aclocal (< 1.8) are no longer supported.
233 *** AC_CONFIG_SUBDIRS no longer directly supports Cygnus configure.
235 If you are still using an Autoconf script to drive configuration of
236 a multi-package build tree where some subdirectories use Cygnus
237 configure, copy or link $ac_aux_dir/configure into each subdirectory
238 where it is needed. Please also contact us; we were under the
239 impression nobody used this very old tool anymore.
241 *** AC_CHECK_HEADER and AC_CHECK_HEADERS only do a compilation test.
243 This completes the transition from preprocessor-based header tests
244 begun in Autoconf 2.56.
246 The double test that was the default since Autoconf 2.64 is no
247 longer available. You can still request a preprocessor-only test
248 by specifying [-] as the fourth argument to either macro, but this
249 is now deprecated. If you really need that behavior use
252 *** AC_INCLUDES_DEFAULT assumes an ISO C90 compliant C implementation.
254 Specifically, it assumes that the ISO C90 header <stddef.h>
255 is available, without checking for it, and it does not include
256 the pre-standard header <memory.h> at all. If the POSIX header
257 <strings.h> exists, it will be included, without first testing
258 whether both <string.h> and <strings.h> can be included in the
261 AC_INCLUDES_DEFAULT still checks for the existence of <stdlib.h>,
262 <string.h>, and <stdio.h>, because these headers may not exist
263 in a “freestanding environment” (a compilation mode intended for OS
264 kernels and similar, where most of the features of the C library are
265 optional). Most programs need not use ‘#ifdef HAVE_STDLIB_H’ etc in
268 For compatibility’s sake, the C preprocessor macro STDC_HEADERS
269 will be defined when both <stdlib.h> and <string.h> are available;
270 however, <stdarg.h> and <float.h> are no longer checked for
271 (these, like <stddef.h>, are required to exist in a freestanding
272 environment). New code should not refer to this macro.
274 Future releases of Autoconf may reduce the set of headers checked
275 for by AC_INCLUDES_DEFAULT.
277 *** AS_ECHO and AS_ECHO_N unconditionally use ‘printf’.
279 This is substantially simpler, more reliable, and, in most cases,
280 faster than attempting to use ‘echo’ at all. However, if ‘printf’
281 is not a shell builtin, configure scripts will run noticeably
282 slower, and if ‘printf’ is not available at all, they will crash.
283 The only systems where this is known to be a problem are extremely
284 old, and unlikely to be able to handle modern C programs for other
285 reasons (e.g. not having a C90-compliant compiler at all).
287 *** Configure scripts require support for $( ... ) command substitution.
289 This POSIX shell feature is approximately the same age as
290 user-defined functions, but there do exist shells that support
291 functions and not $( ... ), such as Solaris 10 /bin/sh.
293 Configure scripts will automatically locate a shell that supports
294 this feature and re-execute themselves with it, if necessary, so
295 the new requirement should be transparent to most users.
297 In this release, most of Autoconf’s code still uses the older `...`
298 notation for command substitution.
300 *** AC_INIT now trims extra white space from its arguments.
302 For instance, AC_INIT([ GNU Hello ], [1.0]) will set PACKAGE_NAME
305 *** Macros that take whitespace-separated lists as arguments
306 now always expand macros within those arguments.
308 Formerly, these macros would *usually* expand those arguments, but
309 the behavior was not reliable nor was it consistent between autoconf
312 Macro expansion within these arguments is deprecated; if expansion
313 changes the list, a warning in the “obsolete” category will be
314 emitted. Note that ‘dnl’ is a macro. Putting ‘dnl’ comments inside
315 any argument to an Autoconf macro is, in general, only supported
316 when that argument takes more Autoconf code (e.g. the ACTION-IF-TRUE
317 argument to AC_COMPILE_IFELSE).
319 The affected macros are AC_CHECK_FILES, AC_CHECK_FUNCS,
320 AC_CHECK_FUNCS_ONCE, AC_CHECK_HEADERS, AC_CHECK_HEADERS_ONCE,
321 AC_CONFIG_MACRO_DIRS, AC_CONFIG_SUBDIRS, and AC_REPLACE_FUNCS.
323 *** AC_FUNC_VFORK no longer ignores a signal-handling bug in Solaris 2.4.
325 This bug was being ignored because Emacs wanted to use ‘vfork’ on
326 Solaris 2.4 anyway, but current versions of Emacs have dropped
327 support for Solaris 2.4. Most programs will want to avoid ‘vfork’
328 on this OS because of this bug.
330 *** AC_FUNC_STRERROR_R assumes strerror_r is unavailable if it’s not declared.
332 The fallback technique it used to probe strerror_r’s return type
333 when the function was present in the C library, but not declared by
334 <string.h>, was fragile and did not work at all when cross-compiling.
335 The systems where this fallback was necessary were all obsolete.
337 Programs that use AC_FUNC_STRERROR_R should make sure to test the
338 preprocessor macro HAVE_DECL_STRERROR_R before using strerror_r at all.
340 *** AC_OPENMP can’t be used if you have files named ‘mp’ or ‘penmp’.
342 Autoconf will now issue an error if AC_OPENMP is used in a configure
343 script that’s in the same directory as a file named ‘mp’ or ‘penmp’.
344 Configure scripts that use AC_OPENMP will now error out upon
345 encountering files with these names in their working directory
346 (e.g. when the build directory is separate from the source directory).
348 If you have files with these names at the top level of your source
349 tree, we recommend either renaming them or moving them into a
350 subdirectory. See the documentation of AC_OPENMP for further
355 *** Configure scripts now support a ‘--runstatedir’ option.
357 This defaults to ‘${localstatedir}/run’. It can be used, for
358 instance, to place per-process temporary runtime files (such as pid
359 files) into ‘/run’ instead of ‘/var/run’.
361 *** autoreconf will now run gtkdocize and intltoolize when appropriate.
363 *** autoreconf now recognizes AM_GNU_GETTEXT_REQUIRE_VERSION.
365 This macro can be used with gettext 0.19.6 or later to specify
366 a *minimum* version requirement for gettext, instead of the *fixed*
367 version requirement specified by AM_GNU_GETTEXT_VERSION.
369 *** autoheader handles secondary config headers better.
371 It is no longer necessary to duplicate AC_DEFINE templates in the
372 main configuration header for autoheader to notice them.
374 *** AC_PROG_CC now enables C2011 mode if the compiler supports it.
376 If not, it will fall back to C99 and C89, as before. Similarly,
377 AC_PROG_CXX now enables C++2011 if available, falling back on C++98.
379 *** New macro AC_C__GENERIC tests for C2011 _Generic support.
381 *** AC_C_VARARRAYS has been aligned with C2011.
383 It now defines __STDC_NO_VLA__ if variable-length arrays are not
384 supported but the compiler does not define __STDC_NO_VLA__.
386 For backward compatibility with Autoconf 2.61-2.69 AC_C_VARARRAYS
387 still defines HAVE_C_VARARRAYS, but this result macro is obsolescent.
389 *** New macro AC_CONFIG_MACRO_DIRS.
391 This macro can be used more than once and accepts a list of
392 directories to search for local M4 macros. With Automake 1.13 and
393 later, use of this macro eliminates a reason to use ACLOCAL_AMFLAGS
396 The older AC_CONFIG_MACRO_DIR, which could only be used once, is
397 still supported but considered deprecated.
399 *** AC_USE_SYSTEM_EXTENSIONS knows about more extensions to enable.
401 System extensions will now be enabled on HP-UX, macOS, and MINIX.
402 Optional ISO C library components (e.g. decimal floating point) will
405 *** New compatibility macro AC_CHECK_INCLUDES_DEFAULT.
407 This macro runs the checks normally performed as a side-effect by
408 AC_INCLUDES_DEFAULT, if they haven’t already been done. Autoupdate
409 will replace certain obsolete constructs, whose only remaining
410 useful effect is to trigger those checks, with this macro. It is
411 unlikely to be useful otherwise.
413 *** AC_REQUIRE_AUX_FILE has been improved.
415 Configure scripts now check, on startup, for the availability of all
416 the aux files that were mentioned in an AC_REQUIRE_AUX_FILE
417 invocation. This should help prevent certain classes of packaging
420 Also, it is no longer necessary for third-party macros that use
421 AC_REQUIRE_AUX_FILE to mention AC_CONFIG_AUX_DIR_DEFAULT. However,
422 if you are using AC_CONFIG_AUX_DIR_DEFAULT *without* also using
423 AC_REQUIRE_AUX_FILE, please start using AC_REQUIRE_AUX_FILE to
424 specify the aux files you actually need, so that the check can be
427 *** AC_PROG_LEX has an option to not look for yywrap.
429 AC_PROG_LEX now takes one argument, which may be either ‘yywrap’ or
430 ‘noyywrap’. If it is ‘noyywrap’, AC_PROG_LEX will only set LEXLIB
431 to ‘-lfl’ or ‘-ll’ if a scanner that defines both main and yywrap
432 itself still needs something else from that library. On the other
433 hand, if it is ‘yywrap’, AC_PROG_LEX will fail (setting LEX to ‘:’
434 and LEXLIB to nothing) if it can’t find a library that defines yywrap.
436 In the absence of arguments, AC_PROG_LEX’s behavior is bug-compatible
437 with 2.69, which did neither of the above things (see the manual for
438 details). This mode is deprecated.
440 We encourage all programs that use AC_PROG_LEX to use the new
441 ‘noyywrap’ mode, and to define yywrap themselves, or use %noyywrap.
442 The yywrap function in lib(f)l is trivial, and self-contained
443 scanners are easier to work with.
445 ** Obsolete features and new warnings
447 *** Use of the long-deprecated name ‘configure.in’ for the autoconf
448 input file now elicits a warning in the “obsolete” category.
450 *** Use of the undocumented internal shell variables $as_echo and
451 $as_echo_n now elicits a warning in the “obsolete” category.
452 The macros AS_ECHO and AS_ECHO_N should be used instead.
454 *** autoconf will now issue warnings (in the “syntax” category)
455 if the input file is missing a call to AC_INIT and/or AC_OUTPUT.
457 *** autoconf will now issue warnings (in the “syntax” category)
458 for a non-literal URL argument to AC_INIT, and for a TARNAME
459 argument to AC_INIT which is either non-literal or contains
460 characters that should not be used in file names (e.g. ‘*’).
462 *** AC_PROG_CC_STDC, AC_PROG_CC_C89, AC_PROG_CC_C99 are now obsolete.
464 Applications should use AC_PROG_CC.
466 *** AC_HEADER_STDC and AC_HEADER_TIME are now stubs.
468 They still define the C preprocessor macros STDC_HEADERS and
469 TIME_WITH_SYS_TIME, respectively, but they no longer check for the
470 ancient, non-ISO-C90 compliant systems where formerly those macros
471 would not be defined. Autoupdate will remove them.
473 These macros were already labeled obsolete in the manual.
475 *** AC_DIAGNOSE, AC_FATAL, AC_WARNING, and _AC_COMPUTE_INT are now
476 replaced with modern equivalents by autoupdate.
478 These macros were already labeled obsolete in the manual.
480 *** AC_CONFIG_HEADER is now diagnosed as obsolete, and replaced with
481 AC_CONFIG_HEADERS by autoupdate.
483 This macro has been considered obsolete for many years and was not
486 *** The macro AC_OBSOLETE is obsolete.
488 Autoupdate will replace it with m4_warn([obsolete], [explanation]).
489 If possible, macros using AC_OBSOLETE should be converted to use
490 AU_DEFUN or AU_ALIAS instead, which enables autoupdate to replace
491 them, but this has to be done by hand and is not always possible.
493 This macro has been considered obsolete for many years, but was not
494 officially declared as such.
496 *** Man pages for config.guess and config.sub are no longer provided.
498 They were moved to the master source tree for config.guess and
503 *** Compatible with current Automake, Libtool, Perl, Texinfo, and shells.
505 All of autoconf’s tools and generated scripts, and the build process
506 and testsuite for autoconf itself, have been tested to work
507 correctly with current versions of Automake, Libtool, Perl, Texinfo,
508 bash, ksh93, zsh, and FreeBSD and NetBSD /bin/sh.
510 Generated configure scripts are expected to work reliably with an
511 even wider variety of shells, including BusyBox sh and various
512 proprietary Unixes’ /bin/sh, as long as they are minimally compliant
513 with the Unix95 shell specification. Notably, support for
514 shell-script functions and the ‘printf’ builtin are required.
516 *** Checks compatible with current language standards and compilers.
518 Many individual macros have been improved to accommodate changes in
519 recent versions of the C and C++ language standards, and new
520 features and quirks of commonly used compilers (both free and
523 *** Improved support for cross compilation.
525 Many individual macros have been improved to produce more accurate
526 results when cross-compiling.
528 *** Improved robustness against unusual build environments.
530 Many bugs have been fixed where generated configure scripts would
531 fail catastrophically under unusual conditions, such as stdout being
532 closed, or $TMPDIR not being an absolute path, or the root directory
533 being mentioned in $PATH.
535 *** AC_CHECK_FUNCS_ONCE and AC_CHECK_HEADERS_ONCE now support multiple
536 programming languages. They no longer perform all checks in the
537 language active upon the first use of the macro.
539 *** AC_CHECK_DECL and AC_CHECK_DECLS will now detect missing declarations for
540 library functions that are also Clang compiler builtins.
542 *** AC_PATH_X and AC_PATH_XTRA don’t search for X11 when cross-compiling.
544 Libraries and headers found by running xmkmf or searching /usr/X11,
545 /usr/X11R7, etc. are likely to belong to a native X11 installation
546 for the build machine and to be inappropriate for cross compilation.
548 To cross-compile programs that require X11, we recommend putting the
549 headers and libraries for the host system in your cross-compiler’s
550 default search paths. Alternatively, use configure’s --x-includes
551 and --x-libraries command line options to tell it where they are.
553 *** AS_IF’s if-false argument may be empty after macro expansion.
555 This long-standing limitation broke configure scripts that used
556 macros in this position that emitted shell code in 2.69 but no
557 longer do, so we have lifted it.
559 *** AC_HEADER_MAJOR detects the location of the major, minor, and
560 makedev macros correctly under glibc 2.25 and later.
562 *** AC_FC_LINE_LENGTH now documents the maximum portable length of
563 “unlimited” Fortran source code lines to be 250 columns, not 254.
565 *** AC_INIT and AS_INIT no longer embed (part of) the path to the
566 source directory in generated files.
568 We believe this was the only case where generated file contents
569 could change depending on the environment outside the source tree
570 itself. If you find any other cases please report them as bugs.
572 *** config.log properly escapes arguments in the header comment.
574 *** config.status --config output is now quoted in a more readable fashion.
576 ** Autotest enhancements
578 *** Autotest provides a new macro AT_DATA_UNQUOTED, similar to AT_DATA
579 but processing variable substitutions, command substitutions and
580 backslashes in the contents argument.
582 *** AC_CONFIG_TESTDIR will automatically pass EXEEXT to a testsuite (via
585 *** AT_TESTED arguments can use variable or command substitutions, including
586 in particular $EXEEXT
588 *** New macros AT_PREPARE_TESTS, AT_PREPARE_EACH_TEST, and AT_TEST_HELPER_FN.
590 These provide an official way to define testsuite-specific
591 initialization code and shell functions.
593 * Noteworthy changes in release 2.69 (2012-04-24) [stable]
595 ** Autoconf now requires perl 5.6 or better (but generated configure
596 scripts continue to run without perl).
598 * Noteworthy changes in release 2.68b (2012-03-01) [beta]
599 Released by Eric Blake, based on git versions 2.68.*.
601 ** Autoconf-generated configure scripts now unconditionally re-execute
602 themselves with $CONFIG_SHELL, if that's set in the environment.
604 ** The texinfo documentation no longer specifies "front-cover" or
605 "back-cover" texts, so that it may now be included in Debian's
608 ** Support for the Go programming language has been added. The new macro
609 AC_LANG_GO sets variables GOC and GOFLAGS.
611 ** AS_LITERAL_IF again treats '=' as a literal. Regression introduced in
614 ** The macro AS_EXECUTABLE_P, present since 2.50, is now documented.
618 - AC_PROG_LN_S and AS_LN_S now fall back on 'cp -pR' (not 'cp -p') if 'ln -s'
619 does not work. This works better for symlinks to directories.
621 - New macro AC_HEADER_CHECK_STDBOOL.
623 - New and updated macros for Fortran support:
625 AC_FC_CHECK_BOUNDS to enable array bounds checking
626 AC_F77_IMPLICIT_NONE and AC_FC_IMPLICIT_NONE to disable implicit integer
627 AC_FC_MODULE_EXTENSION to compute the Fortran 90 module name extension
628 AC_FC_MODULE_FLAG for the Fortran 90 module search path flag
629 AC_FC_MODULE_OUTPUT_FLAG for the Fortran 90 module output directory flag
630 AC_FC_PP_SRCEXT for preprocessed Fortran source files extensions
631 AC_FC_PP_DEFINE for the Fortran preprocessor define flag
633 * Noteworthy changes in release 2.68 (2010-09-22) [stable]
634 Released by Eric Blake, based on git versions 2.67.*.
636 ** AC_MSG_ERROR (and AS_ERROR) can once again be followed immediately by
637 'dnl'. Regression introduced in 2.66.
639 ** AC_INIT again allows URLs with '?' for its BUG-REPORT argument.
640 Regression introduced in 2.66.
642 ** AC_REPLACE_FUNCS again allows a non-literal argument, such as a shell
643 variable that expands to a list of functions to check. Regression
646 ** AT_BANNER() with empty argument will cause visual separation from previous
649 ** The macros AC_PREPROC_IFELSE, AC_COMPILE_IFELSE, AC_LINK_IFELSE, and
650 AC_RUN_IFELSE now warn if the first argument failed to use
651 AC_LANG_SOURCE or AC_LANG_PROGRAM to generate the conftest file
652 contents. A new macro AC_LANG_DEFINES_PROVIDED exists if you have
653 a compelling reason why you cannot use AC_LANG_SOURCE but must
656 ** The macro m4_define_default is now documented.
658 ** Symlinked config.cache files are supported; configure now tries to
659 update non-symlinked cache files atomically, so that concurrent configure
660 runs do not leave behind broken cache files. It is still unspecified
661 which subset or union of results is cached though.
663 ** Autotest testsuites should not contain long text lines any more, and be
664 portable even when very many test groups are used.
666 ** AT_CHECK semantics with respect to the Autotest variable $at_status and
667 shell execution environment of the arguments are documented now.
669 ** AC_FC_LIBRARY_LDFLAGS now tolerates output from newer gfortran.
671 ** Newly obsolete macros
672 The following macros have been marked obsolete. New programs
673 should use the corresponding Gnulib modules. Gnulib not only
674 detects a larger set of portability problems with these functions,
675 but also provides complete workarounds.
677 AC_FUNC_ERROR_AT_LINE AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK
678 AC_FUNC_MKTIME AC_FUNC_STRTOD
681 * Major changes in Autoconf 2.67 (2010-07-21) [stable]
682 Released by Eric Blake, based on git versions 2.66.*.
684 ** AC_CONFIG_SUBDIRS with more than one subdirectory at a time works again.
685 Regression introduced in 2.66.
687 ** AC_CHECK_SIZEOF of a pointer type works again. Regression introduced in
690 ** New macro AC_FC_LINE_LENGTH to accept long Fortran source code lines.
692 ** AC_PREPROC_IFELSE now keeps the preprocessed output in the conftest.i
693 file for inspection by the commands in the ACTION-IF-TRUE argument.
695 ** AC_INIT again allows parentheses and other characters that are literal
696 in single- or double-quoted strings, and in quoted and unquoted
697 here-documents, for its PACKAGE and VERSION arguments. Regression
700 ** autoreconf passes warning flags to new enough versions of aclocal.
702 ** Running an Autotest testsuite in parallel mode no longer triggers a
703 race condition that could cause the testsuite run to end early,
704 fixing a sporadic failure in autoconf's own testsuite. Bug present
705 since introduction of parallel tests in 2.63b.
708 * Major changes in Autoconf 2.66 (2010-07-02) [stable]
709 Released by Eric Blake, based on git versions 2.65.*.
711 ** AC_FUNC_MMAP works in C++ mode again. Regression introduced in 2.65.
713 ** Use of m4_divert without a named diversion now issues a syntax warning,
714 since it is seldom right to change diversions behind autoconf's back.
716 ** The macros AC_TYPE_INT8_T, AC_TYPE_INT16_T, AC_TYPE_INT32_T, and
717 AC_TYPE_INT64_T work again. Regression introduced in 2.65.
719 ** AC_PROG_INSTALL correctly uses 'shtool' again. Regression introduced
722 ** Autoconf should work on EBCDIC hosts.
724 ** AC_CHECK_DECL and AC_CHECK_DECLS accept optional function argument types
725 for overloaded C++ functions.
727 ** AS_SET_CATFILE accepts nonliterals in its variable name argument now.
729 ** Autotest testsuites accept an option --recheck to rerun tests that
730 failed or passed unexpectedly during the last non-debug testsuite run.
732 ** AC_ARG_ENABLE and AC_ARG_WITH now also accept '+' signs in '--enable-*'
733 and '--with-*' arguments, converting them to underscores for the variable
736 ** In configure scripts, loading CONFIG_SITE no longer searches PATH,
737 and problems in loading the configuration site files are diagnosed.
739 ** Autotest testsuites may optionally provide colored test results.
741 ** The previously undocumented Autotest macros AT_ARG_OPTION and
742 AT_ARG_OPTION_ARG have seen bug fixes and are documented now.
743 AT_ARG_OPTION has been changed in that the negative of a long option
744 --OPTION is now --no-OPTION rather than --noOPTION.
746 ** The macro AS_LITERAL_IF is slightly more conservative; text
747 containing shell quotes are no longer treated as literals.
748 Furthermore, a new macro, AS_LITERAL_WORD_IF, adds an additional
749 level of checking that no whitespace occurs in literals.
751 ** The macros AS_TR_SH and AS_TR_CPP no longer expand their results.
753 ** The following macros are now documented:
756 ** New macro AC_FC_FIXEDFORM to accept fixed-form Fortran.
759 * Major changes in Autoconf 2.65 (2009-11-21) [stable]
760 Released by Eric Blake, based on git versions 2.64.*.
762 ** Autoconf is now licensed under the General Public License version 3
763 or later (GPLv3+). As with earlier versions, the license includes
764 an exception clause so that you may release a configure script
765 generated by autoconf under the license of your own program.
767 ** New macros to support Objective C++.
768 AC_PROG_OBJCXX AC_PROG_OBJCXXCPP
770 ** The following undocumented autoconf macros, removed in Autoconf 2.64,
771 have been reinstated:
774 These macros are present only for backwards compatibility purposes.
776 ** The macro AC_LANG_COMPILER no longer fails on embedded systems that
777 lack fopen in the C library, such as AVR or RTEMS (regression
780 ** The AC_FC_FREEFORM macro no longer suffers from a whitespace bug that
781 made it fail with some Fortran compilers (regression introduced in
784 ** The AC_TYPE_UINT64_T and AC_TYPE_INT64_T macros have been fixed to no
785 longer mistakenly select a 32-bit type on some compilers (bug present
786 since macros were introduced in 2.59c).
788 ** The AC_FUNC_MMAP macro has been fixed to be portable to systems like
789 Cygwin (bug present since macro was introduced in 2.0).
791 ** The following documented autotest macros are new:
794 ** The following m4sugar macros now quote their expansion:
795 m4_toupper m4_tolower
797 ** The following m4sugar macros are new:
800 ** The m4sugar macro m4_text_wrap now copes with embedded quoting without
801 requiring quadrigraphs. For uses like AC_ARG_VAR([a], [[b c]]),
802 this gives the intuitive behavior of "[b c]" in the output (2.63
803 gave the output of "[b], [c]", and 2.64 encountered a failure).
805 ** The '$tmp' temporary directory used in config.status is documented for
808 ** config.status now provides a --config option to produce the configuration.
810 ** Many cache variables used by Autoconf's macros are now documented.
812 ** Configure scripts work better on DJGPP by avoiding a bug present in
813 the DJGPP port of bash 2.04 in handling 'return' in a shell
814 function (regression introduced in 2.64).
816 * Major changes in Autoconf 2.64 (2009-07-26) [stable]
817 Released by Eric Blake, based on git versions 2.63b.*.
819 ** Autoconf now requires GNU M4 1.4.6 or later. Earlier versions of M4
820 have a bug in regular expression handling that interferes with some
821 of the speedups provided since Autoconf 2.63. GNU M4 1.4.13 or
822 later is recommended.
824 ** AS_IF and AS_CASE have been taught to avoid syntax errors even when
825 given arguments that expand to just whitespace.
827 ** The following documented autoconf macros are new:
828 AC_ERLANG_SUBST_ERTS_VER
830 ** The autoheader tool now understands m4 macro arguments passed to
831 AC_DEFINE and AC_DEFINE_UNQUOTED.
833 ** Ensure AT_CHECK can support commands that include a # given with
834 proper m4 quoting. For shell comments, this is a new feature; for
835 non-shell comments, this fixes a regression introduced in 2.63b.
836 Additionally, AT_CHECK correctly supplies shell escapes for
837 metacharacters occurring in m4 macro expansions within the expected
838 stdout and stderr parameters.
840 ** The macro AT_CHECK now understands the concept of hard failure. If
841 a test exits with an unexpected status 99, cleanup actions for the
842 test are inhibited and the test is treated as a failure regardless
843 of AT_XFAIL_IF. It also understands the new directives
844 ignore-nolog, stdout-nolog, and stderr-nolog.
846 ** The following documented autotest macros are new:
847 AT_CHECK_UNQUOTED AT_FAIL_IF AT_SKIP_IF
849 ** The following documented m4sugar macros are new:
850 m4_argn m4_copy_force m4_default_nblank m4_default_nblank_quoted
851 m4_ifblank m4_ifnblank m4_rename_force
853 ** The autoconf testsuite now exercises all Erlang macros.
855 * Major changes in Autoconf 2.63b (2009-03-31) [beta]
856 Released by Eric Blake, based on git versions 2.63.*.
858 ** The manual is now shipped under the terms of the GNU FDL 1.3.
860 ** AC_REQUIRE now detects the case of an outer macro which first expands
861 then later indirectly requires the same inner macro. Previously,
862 this case led to silent out-of-order expansion (bug present since
863 2.50); it now issues a syntax warning, and duplicates the expansion
864 of the inner macro to guarantee dependencies have been met. See
865 the manual for advice on how to refactor macros in order to avoid
866 the bug in earlier autoconf versions and avoid increased script
867 size in the current version.
869 ** AC_DEFUN_ONCE has improved semantics. Previously, a macro declared
870 with AC_DEFUN_ONCE warned on a second invocation; and out-of-order
871 expansion was still possible. Now, dependencies are guaranteed,
872 and subsequent invocations are a silent no-op. This makes
873 AC_DEFUN_ONCE an ideal macro for silencing AC_REQUIRE warnings.
875 ** The following macros are now defined with AC_DEFUN_ONCE. This means
876 a subtle change in semantics; previously, an AC_DEFUN macro could
877 expand one of these macros multiple times or surround the macro
878 inside shell conditional text to bypass the effects of these
879 macros, but now the macro will expand exactly once, and prior to
880 the start of any enclosing AC_DEFUN macro:
881 AC_CANONICAL_BUILD AC_CANONICAL_HOST AC_CANONICAL_TARGET
882 AC_HEADER_ASSERT AC_PROG_INSTALL AC_PROG_MKDIR_P
883 AC_USE_SYSTEM_EXTENSIONS
885 ** AC_LANG_ERLANG works once again (regression introduced in 2.61a).
887 ** AC_HEADER_ASSERT is fixed so that './configure --enable-assert' no
888 longer mistakenly disables assertions.
890 ** AC_INIT now takes an optional fifth parameter that can be used to
891 set AC_PACKAGE_URL, a URL for the package's home page; the URL is
892 used in 'configure --help' and is also available via AC_DEFINE.
894 ** Autotest testsuites accept an option --jobs[=N] for parallel testing.
895 This feature is still in testing, and may not work on every
896 platform, help in improving it would be appreciated.
898 ** Autotest testsuites do not attempt to write startup error messages
899 to the log file before that is opened (regression introduced in 2.63).
901 ** Configure scripts now use shell functions. This feature leads to
902 smaller configure files and faster execution.
904 ** Present But Cannot Be Compiled: Autoconf will now proceed with
905 the compiler's result if a header is present but cannot be compiled.
906 The warning is still printed, and you should really fix it by
907 providing a fourth parameter to AC_CHECK_HEADER/AC_CHECK_HEADERS.
909 ** Autoreconf added aclocal to the set of programs affected by the
910 'autoreconf -I dir' option.
912 ** The following documented m4sugar macros are new:
913 m4_chomp m4_chomp_all m4_cleardivert m4_curry m4_default_quoted
914 m4_esyscmd_s m4_map_args m4_map_args_pair m4_map_args_sep
915 m4_map_args_w m4_set_map m4_set_map_sep m4_stack_foreach
916 m4_stack_foreach_lifo m4_stack_foreach_sep
917 m4_stack_foreach_sep_lifo
919 ** The following m4sugar macros are documented now, but in some cases
920 with slightly different semantics than what the previous
921 undocumented version had:
922 m4_copy m4_dumpdefs m4_rename m4_version_prereq
924 ** The m4sugar macro m4_expand has been taught to handle unterminated
925 comments and shell case statements. As a result, it is used
926 internally in more places, such as AC_DEFINE and AT_CHECK. Most
927 uses of AC_DEFINE and AT_CHECK should not behave any differently;
928 however, it may be necessary to add double-quoting around
929 unbalanced '(' where single-quoting used to be sufficient.
931 ** The following documented m4sh macros are new:
932 AS_INIT_GENERATED AS_LINENO_PREPARE AS_ME_PREPARE AS_SET_STATUS
933 AS_VAR_APPEND AS_VAR_ARITH AS_VAR_COPY
935 ** The following m4sh macros are documented now, but in some cases
936 with slightly different semantics than what the previous
937 undocumented version had:
938 AS_ECHO AS_ECHO_N AS_ESCAPE AS_EXIT AS_LITERAL_IF AS_UNSET
939 AS_VAR_IF AS_VAR_POPDEF AS_VAR_PUSHDEF AS_VAR_SET AS_VAR_SET_IF
940 AS_VAR_TEST_SET AS_VERSION_COMPARE
942 ** The m4sh macros AS_IF and AS_CASE can now be used in shell lists.
943 The responsibility for supplying a trailing newline now belongs to
944 the call site, but since most users did not add dnl, this generally
945 results in fewer empty lines in configure.
948 * Major changes in Autoconf 2.63 (2008-09-09) [stable]
949 Released by Eric Blake, based on git versions 2.62.*.
951 ** AC_C_BIGENDIAN does not mistakenly report "universal" for some
952 bigendian hosts, a regression introduced with universal binary
955 ** AC_PATH_X now includes /lib64 and /usr/lib64 in its list of default
958 ** AC_USE_SYSTEM_EXTENSIONS no longer conflicts with an external
959 AC_DEFINE([__EXTENSIONS__]). This fixes a regression introduced in
960 2.62 when using macros such as AC_AIX that were made obsolete in
961 favor of the more portable AC_USE_SYSTEM_EXTENSIONS.
963 ** AC_CHECK_TARGET_TOOLS is usable in the non-cross-compile case.
965 ** Newly obsolete macros
966 The following macro has been marked obsolete, since current porting
967 targets can safely assume C89 semantics that signal handlers return
968 void. We have no current plans to remove the macro.
972 ** The macros m4_map and m4_map_sep now ignore any list elements
973 consisting of just empty quotes, and m4_map_sep now expands its
974 separator. This fixes a regression in 2.62 when these macros were
975 first documented, for the sake of clients expecting the semantics
976 that these macros had prior to that time. The new macros m4_mapall
977 and m4_mapall_sep, along with extra quoting of the separator, can
978 be used to get the semantics that m4_map_sep had in 2.62.
980 ** Clients of m4_expand, such as AS_HELP_STRING and AT_SETUP, can now
981 handle properly quoted but otherwise unbalanced parentheses (for
982 some macros, this fixes a regression in 2.62).
984 ** Two new quadrigraphs have been introduced: @{:@ for (, and @:}@ for ),
985 allowing the output of unbalanced parentheses in more contexts.
987 ** The following m4sugar macros are new:
988 m4_cleardivert m4_joinall m4_mapall m4_mapall_sep m4_reverse
989 m4_set_add m4_set_add_all m4_set_contains m4_set_contents
990 m4_set_delete m4_set_difference m4_set_dump m4_set_empty
991 m4_set_foreach m4_set_intersection m4_set_list m4_set_listc
992 m4_set_remove m4_set_size m4_set_union
994 ** The following m4sugar macros now accept multiple arguments, as is the
995 case with underlying m4:
996 m4_defn m4_popdef m4_undefine
998 ** The following m4sugar macros now guarantee linear scaling; they
999 previously had linear scaling with m4 1.6 but quadratic scaling
1000 when using m4 1.4.x. All macros built on top of these also gain
1001 the scaling improvements.
1002 m4_bmatch m4_bpatsubsts m4_case m4_cond m4_do m4_dquote_elt
1003 m4_foreach m4_join m4_list_cmp m4_map m4_map_sep m4_max
1006 ** AT_KEYWORDS once again performs expansion on its argument, such that
1007 AT_KEYWORDS([m4_if([$1], [], [default])]) no longer complains about
1008 the possibly unexpanded m4_if [regression introduced in 2.62].
1010 ** Config header templates '#undef UNDEFINED /* comment */' do not lead to
1011 nested comments any more; regression introduced in 2.62.
1014 * Major changes in Autoconf 2.62 (2008-04-05) [stable]
1015 Released by Eric Blake, based on git versions 2.61a.*.
1017 ** Many optimizations have been applied to make overall execution faster.
1019 ** Autotest now makes use of shell functions.
1021 ** config.status now uses awk instead of sed also for config headers.
1023 - As a side effect, AC_DEFINE and AC_DEFINE_UNQUOTED now handle multi-line
1024 values, i.e., backslash-newline combinations are handled correctly.
1025 Further, for config headers, the total size of values is not limited by
1026 the POSIX length limit of text lines any more, only each single line.
1028 ** New config variable 'top_build_prefix'.
1030 ** New Autoconf macros:
1031 AC_AUTOCONF_VERSION AC_OPENMP AC_PATH_PROGS_FEATURE_CHECK
1033 ** AC_C_BIGENDIAN now supports universal binaries a la Mac OS X.
1035 ** AC_C_RESTRICT now prefers to #define 'restrict' to a variant spelling
1036 like '__restrict' if the variant spelling is available, as this is
1037 more likely to work when mixing C and C++ code.
1039 ** AC_CHECK_ALIGNOF's type argument T is now documented better: it must
1040 be a string of tokens such that "T y;" is a valid member declaration
1043 ** AC_CHECK_SIZEOF now accepts objects as well as types: the general rule
1044 is that sizeof (X) works, then AC_CHECK_SIZEOF (X) should work.
1046 ** AC_CHECK_TYPE and AC_CHECK_TYPES now work on any C type-name; formerly,
1047 they did not work for function types. In C++, they now work on any
1048 type-id that can be the operand of sizeof; this is similar to C,
1049 except it excludes anonymous struct and union types. Formerly,
1050 some (but not all) C++ types involving anonymous struct and union
1051 were accepted, though this was not documented.
1053 ** AC_CONFIG_LINKS now prefers to link against files in the build tree
1054 if found, and it works to link against a file of the same name in
1055 the source tree, even if both trees coincide.
1057 ** AC_INIT no longer alters $@; regression introduced in 2.60.
1059 ** AC_USE_SYSTEM_EXTENSIONS now defines _ALL_SOURCE for Interix platforms.
1061 ** AS_HELP_STRING no longer underquotes its first argument; it also handles
1062 the case where the first argument contains single-quoted commas.
1063 For example, "AS_HELP_STRING([-a, [--arg[=foo]]], [bar])" produces:
1064 " -a, --arg[=foo] bar"
1065 Additionally, the macro now takes two additional arguments,
1066 indent-column and wrap-column; these should not normally be needed,
1067 but can be used to fine-tune how the output text is wrapped.
1069 ** AC_PROG_INSTALL now requires an install program that can install multiple
1070 files into a target directory.
1072 ** The command 'autoconf -' now correctly processes a file from stdin.
1074 ** 'autoreconf -m' now honors $MAKE.
1076 ** For all of the directory arguments for 'configure', such as '--prefix'
1077 or '--bindir', trailing slashes are stripped. As an example, if
1078 tab completion in the user's shell appends trailing slashes, the
1079 command './configure --prefix=/usr/' will still result in an
1080 expanded libdir value of /usr/lib, not /usr//lib.
1082 ** 'configure --help=recursive' now works in read-only trees and from
1083 unconfigured build trees.
1085 ** If precious variables differ only in whitespace, then the cache consistency
1086 check warns instead of fails, and reuses the old value.
1088 ** AT_BANNER is now documented.
1090 ** AT_SETUP now handles macro expansions properly when calculating line
1093 ** Autotest now determines $srcdir correctly.
1095 ** Testsuites built by autotest now accept a -C/--directory=DIR option
1096 to adjust the working directory prior to creating files.
1098 ** Autoconf now requires GNU M4 1.4.5 or later. Earlier versions of M4 have
1099 a bug in macro tracing that interferes with the interaction between
1100 Autoconf and Automake. GNU M4 1.4.11 or later is recommended. The
1101 configure search for a working M4 is improved.
1103 ** For portability with the eventual M4 2.0, macros should no longer use
1104 anything larger than $9 to refer to arguments.
1106 ** Documentation for m4sugar is improved.
1108 - The following macros were previously available as undocumented
1109 interfaces; the macros are now documented as stable interfaces.
1111 __oline__ m4_assert m4_bmatch m4_bpatsubsts m4_car m4_case
1112 m4_cdr m4_default m4_divert_once m4_divert_pop m4_divert_push
1113 m4_divert_text m4_do m4_errprintn m4_fatal m4_flatten
1114 m4_ifndef m4_ifset m4_ifval m4_ifvaln m4_location
1115 m4_n m4_shiftn m4_strip m4_warn
1117 - The following macros were previously available as undocumented
1118 interfaces, but had bug fixes or semantic changes as part of this
1119 release. Packages that relied on the undocumented behavior
1120 should be analyzed to make sure they will still work with the
1121 new documented behavior.
1123 m4_cmp m4_list_cmp m4_join m4_map m4_map_sep m4_sign
1124 m4_text_box m4_text_wrap m4_version_compare
1126 - The m4_wrap macro used to have unspecified order, but now
1127 guarantees FIFO order. m4_wrap_lifo was added to guarantee LIFO
1130 - Packages using the undocumented m4sugar macro m4_PACKAGE_VERSION
1131 should consider using the new AC_AUTOCONF_VERSION instead.
1133 - m4sugar macros that are not documented in the manual are still
1134 deemed experimental, and should not be used outside of Autoconf.
1136 ** The m4sugar macros m4_append and m4_append_uniq, first documented in
1137 2.60, have been fixed to treat both the string and the separator
1138 arguments consistently with regards to quoting. Prior to this fix,
1139 m4_append_uniq could mistakenly duplicate entries if the expansion
1140 of the separator resulted in a different string (for example, if it
1141 contained quotes, a comma, or a macro name). However, it means
1142 that programs previously using
1143 m4_append([name], [string], [[, ]])
1144 are now using a four-character separator instead of the intended
1145 comma and space. If you need portability to earlier versions of
1146 Autoconf, you can insert the following snippet after AC_INIT but
1147 before any other macro expansions, to enforce the new semantics:
1148 m4_pushdef([m4_append], [m4_define([$1],
1149 m4_ifdef([$1], [m4_defn([$1])[$3]])[$2])])
1150 Additionally, m4_append_uniq now takes optional parameters that can
1151 be used to take action depending on whether anything was appended,
1152 and warns if a non-empty separator occurs within the string being
1153 appended, since that can lead to duplicates.
1155 ** The following m4sugar macros are new:
1156 m4_append_uniq_w m4_apply m4_combine m4_cond m4_count
1157 m4_dquote_elt m4_echo m4_expand m4_ignore m4_make_list m4_max
1158 m4_min m4_newline m4_shift2 m4_shift3 m4_unquote m4_wrap_lifo
1160 ** Warnings are now generated by default when an installer invokes
1161 'configure' with an unknown --enable-* or --with-* option.
1162 These warnings can be disabled with the new AC_DISABLE_OPTION_CHECKING
1163 macro, or by invoking 'configure' with --disable-option-checking.
1165 ** Existing obsolete macros
1166 The documentation for the following macros is adjusted to make it
1167 more clear that they have previously been marked obsolete, as their
1168 functionality can be accomplished by other macros. We have no
1169 current plans to remove them from Autoconf.
1171 AC_ENABLE AC_STRUCT_ST_BLKSIZE AC_STRUCT_ST_RDEV AC_WITH
1173 ** Newly obsolete macros
1174 The following macros have been marked obsolete, as they only
1175 perform a subset of AC_USE_SYSTEM_EXTENSIONS. We have no current
1176 plans to remove them.
1178 AC_AIX AC_GNU_SOURCE AC_ISC_POSIX AC_MINIX
1180 ** AC_C_LONG_DOUBLE is obsolescent.
1181 The documentation now says that AC_C_LONG_DOUBLE is obsolescent: it
1182 tests for problems that are so old that it is no longer of
1183 practical importance on current systems. New programs need not use
1184 AC_C_LONG_DOUBLE. We have no current plans to remove it.
1186 ** AC_DIAGNOSE, AC_WARNING, and AC_FATAL are obsolescent.
1187 The documentation now favors the use of M4sugar macros m4_warn and
1188 m4_fatal, since the naming makes it more obvious that the
1189 diagnostics are associated with M4 expansion (ie. when running
1190 'autoconf'), and offers less confusion with the AC_MSG_ERROR,
1191 AC_MSG_FAILURE, and AC_MSG_WARN macros which manage diagnostics
1192 when running 'configure'. We have no current plans to remove these
1196 * Major changes in Autoconf 2.61a (2006-12-11)
1198 ** AC_FUNC_FSEEKO was broken in 2.61; it didn't make fseeko and ftello visible
1199 on many platforms. This has been fixed.
1201 ** AC_FUNC_SETVBUF_REVERSED is now obsolete. It is still defined for backward
1202 compatibility but it does nothing. The macro was already
1203 obsolescent, as the last systems to have the problem were those
1204 based on SVR2, which became obsolete in 1987. The macro had bugs
1205 on some modern systems and could no longer be maintained reliably
1206 due to lack of ancient systems to test it on.
1208 ** config.status now uses awk instead of sed for most substitutions, for speed.
1210 - As a side effect multi-line values of substituted variables no
1211 longer have a small limit in total size, though for portability
1212 each line should not exceed the POSIX length limit for text lines.
1214 - It is now documented that Makefile.in should not contain
1215 overlapping variable occurrences, e.g., @VAR1@VAR2@.
1216 Autoconf's behavior was always iffy in such cases, and the
1217 awk implementation has changed the behavior.
1219 ** Many uses of 'echo' have been rewritten so that Autoconf-generated
1220 scripts have fewer problems with strings or file names containing
1221 embedded special characters such as backslash or leading "-". This
1222 was implemented by using 'printf '%s\n' "$foo"' instead of 'echo
1223 "$foo"' when printf works. Due to the implementation technique
1224 used, Autoconf-generated scripts now run considerably more slowly
1225 on ancient implementations lacking printf. However, this should
1226 not be a problem, since Autoconf-generated scripts in practice
1227 invariably find a more-modern shell these days.
1230 * Major changes in Autoconf 2.61 (2006-11-17)
1232 ** New macros AC_C_FLEXIBLE_ARRAY_MEMBER, AC_C_VARARRAYS.
1234 ** AC_ARG_ENABLE and AC_ARG_WITH now allow '.' in feature and package names.
1237 * Major changes in Autoconf 2.60b (2006-10-22)
1240 Autoconf-generated shell scripts no longer export BIN_SH, due to
1241 configuration hassles with this. Installers who need BIN_SH in
1242 their environment should set it before invoking 'configure' and
1243 'make'. As far as we know, this affects only Unixware installations.
1245 ** Obsolescent macros
1246 The documentation now says that the following macros are obsolescent,
1247 as they are superseded by Gnulib:
1249 AC_FUNC_FNMATCH AC_FUNC_FNMATCH_GNU AC_FUNC_GETLOADAVG
1252 New programs should use the Gnulib counterparts of these macros.
1253 We have no current plans to remove them from Autoconf.
1255 ** AC_COMPUTE_INT no longer caches or reports results.
1257 ** AC_CHECK_DECL now also works with aggregate objects.
1259 ** AC_USE_SYSTEM_EXTENSIONS now defines _TANDEM_SOURCE for NonStop platforms.
1261 ** GNU M4 1.4.7 or later is now recommended.
1264 New M4sugar macro, which is more secure than the POSIX M4 maketemp.
1267 Now an alias for m4_mkstemp.
1269 * Major changes in Autoconf 2.60a (2006-08-25)
1271 ** GNU M4 1.4.6 or later is now recommended.
1273 ** The check for C99 now tests for varargs macros, as documented.
1274 It also tests that the preprocessor supports 64-bit integers.
1276 ** Autoconf now uses constructs like "#ifdef HAVE_STDLIB_H" rather than
1277 "#if HAVE_STDLIB_H", so that it now works with "gcc -Wundef -Werror".
1279 ** The functionality of the undocumented _AC_COMPUTE_INT is now provided
1280 by a public and documented macro, AC_COMPUTE_INT. The parameters to the
1281 two macros are different, so autoupdate will not change the old private name
1282 to the new one. _AC_COMPUTE_INT may be removed in a future release.
1284 ** AC_TYPE_LONG_LONG_INT and AC_TYPE_UNSIGNED_LONG_LONG_INT now require
1285 that long long types be at least 64 bits wide, as C99 and tradition
1286 requires. Formerly, they accepted implementations of any width.
1289 * Major changes in Autoconf 2.60
1291 Released 2006-06-23, by Ralf Wildenhues.
1293 ** Autoconf no longer depends on whether m4wrap is FIFO (as Posix requires)
1294 or LIFO (as in GNU M4 1.4.x). GNU M4 2.0 is expected to conform to Posix
1295 here, so m4wrap/m4_wrap users should no longer depend on LIFO behavior.
1297 ** Provide a way to turn off warnings about the changed directory variables.
1299 * Major changes in Autoconf 2.59d
1301 Released 2006-06-05, by Ralf Wildenhues.
1303 ** GNU make now recommended for VPATH builds
1304 INSTALL now suggests VPATH builds (e.g., "sh ../srcdir/configure")
1305 only if you use GNU make. In practice, other 'make' implementations
1306 have too many subtle incompatibilities in their support for VPATH.
1307 Many packages (including Autoconf itself) are portable to other
1308 'make' implementations, but some packages are not, and recommending
1309 GNU make keeps the installation instructions simpler.
1311 ** Even more safety checks for the new Directory variables:
1312 Warn about suspicious '${datarootdir}' found in config files output.
1314 ** AC_TRY_COMMAND, AC_TRY_EVAL, ac_config_guess, ac_config_sub, ac_configure
1315 These never-documented macros and variables have been marked with
1316 comments saying that they may be removed in a future release,
1317 because their use can lead to unintended code being executed.
1318 If you need functionality that only these macros or variables
1319 currently supply, please write bug-autoconf@gnu.org.
1321 ** AC_SUBST, AC_DEFINE
1322 Literal arguments to these are passed to m4_pattern_allow now.
1325 Passing 'ac_cv_prog_cc_stdc=no' to 'configure' now sets ac_cv_prog_cc_c99
1326 and ac_cv_prog_cc_c89 to 'no' as well, for backward compatibility with
1327 obsolete K&R tests in the Automake test suite.
1336 Now more robust with special characters in file names, or when
1337 multiple processes create the same directory at the same time.
1339 ** Obsolescent macros
1340 The documentation now says that the following macros are obsolescent:
1341 they test for problems that are so old that they are no longer of
1342 practical importance on current systems.
1344 AC_C_BACKSLASH_A AC_FUNC_MEMCMP AC_HEADER_DIRENT
1345 AC_C_CONST AC_FUNC_SELECT_ARGTYPES AC_HEADER_STAT
1346 AC_C_PROTOTYPES AC_FUNC_SETPGRP AC_HEADER_STDC
1347 AC_C_STRINGIZE AC_FUNC_SETVBUF_REVERSED AC_HEADER_SYS_WAIT
1348 AC_C_VOLATILE AC_FUNC_STAT AC_HEADER_TIME
1349 AC_FUNC_CLOSEDIR_VOID AC_FUNC_STRFTIME AC_ISC_POSIX
1350 AC_FUNC_GETPGRP AC_FUNC_UTIME_NULL AC_PROG_GCC_TRADITIONAL
1351 AC_FUNC_LSTAT AC_FUNC_VPRINTF AC_STRUCT_TM
1353 New programs need not use these macros. We have no current plans to
1357 For compatibility with future Libtool 2.0, autoreconf will invoke
1358 libtoolize with the option '--ltdl' now, if LT_CONFIG_LTDL_DIR is
1361 * Major changes in Autoconf 2.59c
1363 Released 2006-04-12, by Ralf Wildenhues.
1365 ** The configure command now redirects standard input from /dev/null,
1366 to help avoid problems with subsidiary commands that might mistakenly
1367 read standard input. AS_ORIGINAL_STDIN_FD points to the original
1368 standard input before this redirection, if you really want configure to
1369 read from standard input.
1371 ** Directory variables adjusted to recent changes in the GNU Coding Standards.
1372 The following directory variables are new:
1374 datarootdir read-only architecture-independent data root [PREFIX/share]
1375 localedir locale-specific message catalogs [DATAROOTDIR/locale]
1376 docdir documentation root [DATAROOTDIR/doc/PACKAGE]
1377 htmldir html documentation [DOCDIR]
1378 dvidir dvi documentation [DOCDIR]
1379 pdfdir pdf documentation [DOCDIR]
1380 psdir ps documentation [DOCDIR]
1382 The following variables have new default values:
1384 datadir read-only architecture-independent data [DATAROOTDIR]
1385 infodir info documentation [DATAROOTDIR/info]
1386 mandir man documentation [DATAROOTDIR/man]
1388 This means that if you use any of '@datadir@', '@infodir@', or
1389 '@mandir@' in a file, you will have to ensure '${datarootdir}' is
1390 defined in this file. As a temporary measure, if any of those are
1391 found but no mention of 'datarootdir', the substitutions will be
1392 replaced with values that do not contain '${datarootdir}', and a
1393 warning will be issued.
1395 ** @top_builddir@ is now a dir name: it is always nonempty and doesn't have
1396 a trailing slash. Similar change will be made to ac_top_builddir in a
1397 future release; the old style value, which matches (../)*, is (and will
1398 continue to be) available as ac_top_build_prefix.
1401 New macro to check for support of 'typeof' syntax a la GNU C.
1403 ** AC_CHECK_DECLS_ONCE, AC_CHECK_FUNCS_ONCE, AC_CHECK_HEADERS_ONCE
1404 New "once-only" variants of commonly-used macros, to make 'configure'
1405 smaller and faster in common cases.
1408 New macro to check for strtold with C99 semantics.
1411 New macro that lets builder disable assertions at 'configure'-time.
1414 Now checks for X11/Xlib.h and XrmInitialize (X proper) rather than
1415 X11/Intrinsic.h and XtMalloc (Xt).
1417 ** AC_PRESERVE_HELP_ORDER
1418 New macro that causes 'configure' to display help strings for AC_ARG_ENABLE
1419 and AC_ARG_WITH arguments in one region, in the order defined. The default
1420 behavior is to group options of each classes separately.
1422 ** AC_PROG_CC, AC_PROG_CXX
1423 No longer automatically arrange to declare the 'exit' function of C,
1424 when a C++ compiler is used. Standard Autoconf macros no longer use
1425 'exit', so this is no longer an issue for them. If you use C++, and
1426 want to call 'exit', you'll have to arrange for its declaration
1427 yourself. But we now suggest you return from 'main' instead.
1429 ** AC_PROG_CC_C89, AC_PROG_CC_C99
1430 New macros for ISO C99 support. AC_PROG_CC_C89 and AC_PROG_CC_C99
1431 check for ANSI C89 and ISO C99 support respectively.
1434 Has been unobsoleted, and will check if the compiler supports ISO
1435 C99, falling back to ANSI C89 if not. ac_cv_prog_cc_stdc is
1436 retained for backwards compatibility, assuming the value of
1437 ac_cv_prog_cc_c99 or ac_cv_prog_cc_c89 (whichever is valid, in
1440 ** AC_STRUCT_DIRENT_D_INO, AC_STRUCT_DIRENT_D_TYPE
1441 New macros for checking commonly-used members of struct dirent.
1444 The substituted value can now contain newlines.
1447 The substitution now occurs only when @variable@ is on a line by itself,
1448 optionally surrounded by spaces and tabs. The whole line is replaced.
1450 ** AC_TYPE_LONG_DOUBLE, AC_TYPE_LONG_DOUBLE_WIDER
1451 New macros to check for long double, and whether it is wider than double.
1452 The old macro AC_C_TYPE_LONG_DOUBLE has been marked as obsolete;
1453 applications should switch to the new macro.
1455 ** AC_TYPE_INT8_T, AC_TYPE_INT16_T, AC_TYPE_INT32_T, AC_TYPE_INT64_T,
1456 AC_TYPE_INTMAX_T, AC_TYPE_INTPTR_T, AC_TYPE_LONG_LONG_INT, AC_TYPE_SSIZE_T,
1457 AC_TYPE_UINT8_T, AC_TYPE_UINT16_T, AC_TYPE_UINT32_T, AC_TYPE_UINT64_T,
1458 AC_TYPE_UINTMAX_T, AC_TYPE_UINTPTR_T, AC_TYPE_UNSIGNED_LONG_LONG_INT
1459 New macros to check for C99 and POSIX types.
1461 ** AC_USE_SYSTEM_EXTENSIONS
1462 New macro to enable extensions to Posix.
1465 New macro which is defined to the name of the first declared config header
1466 or undefined if no config headers have been declared yet.
1469 The macro correctly handles quadrigraphs now.
1471 ** AS_BOURNE_COMPATIBLE, AS_SHELL_SANITIZE, AS_CASE
1472 These macros are new or published now.
1475 New macro for copyright notices in testsuite files.
1477 ** ALLOCA, LIBOBJS, LTLIBOBJS
1478 Object names added to these variables are now prefixed with '${LIBOBJDIR}',
1479 as in '${LIBOBJDIR}alloca.o'. LIBOBJDIR is meant to be defined from
1480 'Makefile.in' in case the object files lie in a different directory.
1481 The LIBOBJDIR feature is experimental.
1484 Supports --no-recursive now.
1486 ** New macros to support Erlang/OTP.
1487 New macros for configuring paths to Erlang tools and libraries:
1488 AC_ERLANG_PATH_ERLC, AC_ERLANG_NEED_ERLC, AC_ERLANG_PATH_ERL,
1489 AC_ERLANG_NEED_ERL, AC_ERLANG_CHECK_LIB, AC_ERLANG_SUBST_ROOT_DIR,
1490 AC_ERLANG_SUBST_LIB_DIR.
1492 New macros for configuring installation of Erlang libraries:
1493 AC_ERLANG_SUBST_INSTALL_LIB_DIR, AC_ERLANG_SUBST_INSTALL_LIB_SUBDIR.
1495 ** The manual now mentions Gnulib more prominently.
1497 ** New macros to support Objective C.
1498 AC_PROG_OBJC, AC_PROG_OBJCPP.
1500 * Major changes in Autoconf 2.59b
1502 Released 2004-08-20, by Paul Eggert.
1505 New macro that computes the default alignment of a type.
1507 ** AC_CHECK_TOOL, AC_PATH_TOOL, AC_CHECK_TOOLS
1508 When cross-compiling, these macros will give a warning if the tool
1509 is not prefixed. In the future, unprefixed cross tools will not
1510 be detected; please consult the info documentation for information
1511 about the reason of this change.
1513 ** AC_CHECK_TARGET_TOOL, AC_PATH_TARGET_TOOL, AC_CHECK_TARGET_TOOLS
1514 New macros that detect programs whose name is prefixed with the
1515 target type, if the build type and target type are different.
1517 ** AC_REQUIRE_AUX_FILE
1518 New trace macro that declares expected auxiliary files.
1521 New macro that tests for a grep program that accepts as a long a line
1524 ** AC_PROG_EGREP, AC_PROG_FGREP
1525 These macros now require AC_PROG_GREP, and try EGREP="$GREP -E" and
1526 FGREP="$GREP -F" respectively if possible, or else run a path search for
1527 a program that accepts as long a line as possible.
1530 New macro that tests for a sed program that truncates as few characters
1533 * Major changes in Autoconf 2.59
1535 Released 2003-11-04, by Akim Demaille
1537 ** ac_abs_builddir etc.
1538 Absolute file names were actually relative in 2.58.
1540 * Major changes in Autoconf 2.58
1542 Released 2003-11-04, by Akim Demaille
1545 core.* files are no longer removed, as they may be valid user files.
1547 ** autoreconf and auxiliary directory
1548 Autoreconf creates the auxiliary directory if needed. This is
1549 especially useful for initial "bootstrapping" of fresh CVS checkouts.
1551 ** AC_CONFIG_MACRO_DIR
1552 Use this macro to declare the directory for local M4 macros for aclocal.
1555 No longer includes twice the same file in LIBOBJS if invoked
1558 ** AC_CONFIG_COMMANDS
1559 The directory for its first argument is automatically created. For
1562 AC_CONFIG_COMMANDS([src/modules.hh], [...])
1564 $top_builddir/src/ is created if needed.
1566 ** Autotest and local.at
1567 The optional file local.at is always included in Autotest test suites.
1570 The warnings are always issued, including with cached runs.
1571 This became a significant problem since aclocal and automake can
1572 run autoconf behind the scene.
1574 ** autoheader warnings
1575 The warnings of autoheader can be turned off, using --warning.
1576 For instance, -Wno-obsolete disables the complaints about acconfig.h
1577 and other deprecated constructs.
1580 AC_C_RESTRICT, AC_INCLUDES_DEFAULT, AC_LANG_ASSERT, AC_LANG_WERROR,
1583 ** AC_DECL_SYS_SIGLIST
1587 Now checks that mktime is the inverse of localtime.
1589 ** Improve DJGPP portability
1590 The Autoconf tools and configure behave better under DJGPP.
1592 ** Present But Cannot Be Compiled
1593 New FAQ section dedicated to the mystic
1595 configure: WARNING: pi.h: present but cannot be compiled
1596 configure: WARNING: pi.h: check for missing prerequisite headers?
1597 configure: WARNING: pi.h: proceeding with the preprocessor's result
1600 ** Concurrent executions of autom4te
1601 autom4te now locks its internal files, which enables concurrent
1602 executions of autom4te, likely to happen if automake, autoconf,
1603 autoheader etc. are run simultaneously.
1606 Use of Libtool 1.5 and higher is encouraged. Compatibility with
1607 Libtool pre-1.4 is not checked.
1610 Testsuites no longer rerun failed tests in verbose mode; instead,
1611 failures are logged while the test is run.
1613 In addition, expected failures can be marked as such.
1615 * Major changes in Autoconf 2.57
1617 Released 2002-12-03 by Paul Eggert.
1619 Bug fixes for problems with AIX linker, with freestanding C compilers,
1620 with GNU M4 limitations, and with obsolete copies of GNU documents.
1622 The Free Documentation License has been upgraded from 1.1 to 1.2.
1624 * Major changes in Autoconf 2.56
1626 Released 2002-11-15 by Akim Demaille.
1628 One packaging problem fixed (config/install-sh was not executable).
1630 * Major changes in Autoconf 2.55
1632 Released 2002-11-14 by Akim Demaille.
1636 Have your configure.ac checked by autoscan ("autoscan").
1637 Try the warning options ("autoreconf -fv -Wall").
1641 - AC_CHECK_HEADER, AC_CHECK_HEADERS
1642 More information on proper use.
1644 - Writing Test Programs
1646 This sections explains how to write good test sources to use with
1647 AC_COMPILE_IFELSE etc. It documents AC_LANG_PROGRAM and so forth.
1649 - AC_FOO_IFELSE vs. AC_TRY_FOO
1651 Explains why Autoconf moves from AC_TRY_COMPILE etc. to
1652 AC_COMPILE_IFELSE and AC_LANG_PROGRAM etc.
1656 - Is more robust to different Gettext installations.
1658 - Produces messages (when --verbose) to be understood by Emacs'
1661 - Supports -W/--warnings.
1664 Once the GNU Build System reinstalled, run './config.status
1665 --recheck && ./config.status && make' if possible.
1669 - Supports --cache, and --no-cache.
1671 - ~/.autom4te.cfg makes it possible to disable the caching mechanism
1672 (autom4te.cache). See 'Customizing autom4te' in the documentation.
1679 Support for the obsoleted options -m, --macrodir, -l, --localdir is
1680 dropped in favor of the safer --include/--prepend-include scheme.
1685 AC_COMPILER_IFELSE, AC_FUNC_MBRTOWC, AC_HEADER_STDBOOL,
1686 AC_LANG_CONFTEST, AC_LANG_SOURCE, AC_LANG_PROGRAM, AC_LANG_CALL,
1687 AC_LANG_FUNC_TRY_LINK, AC_MSG_FAILURE, AC_PREPROC_IFELSE.
1690 Obsoleted macros are kept for Autoconf backward compatibility, but
1691 should be avoided in configure.ac. Running autoupdate is advised.
1692 AC_DECL_SYS_SIGLIST.
1694 - AC_DEFINE/AC_DEFINE_UNQUOTED
1696 We have to stop using the old compatibility scheme --that tried to
1697 avoid useless backslashes-- because Libtool 1.4.3 contains a
1699 AC_DEFINE([error_t], [int],
1700 [Define to a type to use for \`error_t' if it is not
1701 otherwise available.])
1703 We have to quote the single quotes and backslashes with \. The old
1704 compatibility scheme saw that ` was backslashed, and therefore did
1705 not quote the single quote... Failure. Hence, Autoconf 2.54 is not
1706 compatible with Libtool. Autoconf 2.55 is, but in some cases might
1707 produce more \ than wanted.
1709 Please, note that in the future the same problem will happen with
1710 AC_MSG_*: use 'autoreconf -f -Wall'.
1714 - Portability of the Autoconf package to Solaris.
1716 - Spurious warnings caused by config.status.
1717 This bug is benign, but painful: on some systems (typically
1718 FreeBSD), warnings such as:
1720 config.status: creating Makefile
1721 mv: Makefile: set owner/group (was: 1357/0): Operation not permitted
1723 could be issued. This is fixed.
1726 Simultaneous executions of config.status are possible again.
1728 - Precious variables accumulation
1730 config.status could stack several copies of the precious variables
1734 ** Plans for later versions
1736 - ./configure <host>
1738 The compatibility hooks with the old scheme will be completely
1739 removed. Please, advice/use '--build', '--host', and '--target'
1742 - AC_CHECK_HEADER, AC_CHECK_HEADERS
1744 The tests will be stricter, please make sure your invocations are
1749 Shell functions will gradually be introduced, probably starting with
1750 Autotest. If you know machines which are in use that you suspect
1751 *not* to support shell functions, please run the test suite of
1752 Autoconf 2.55 on it, and report the results to
1753 bug-autoconf@gnu.org.
1757 Special characters in AC_MSG_* need not be quoted. Currently,
1758 Autoconf has heuristics to decide when a string is escaped, or has
1759 to be escaped. This scheme is fragile, and will be removed; the
1760 only risk is uglified messages. Please, run 'autoreconf -f -Wall'
1761 to find occurrences that will be affected.
1763 * Major changes in Autoconf 2.54
1765 Released 2002-09-13 by Akim Demaille.
1769 - autoreconf no longer changes the version of the gettext/po/intl
1770 support files. It now adds the files the correspond to the
1771 AM_GNU_GETTEXT_VERSION declared in configure.ac.
1773 Warning: It now relies on the 'autopoint' program, which is part
1774 of GNU gettext 0.11.4 and newer.
1776 Please note that you need to have a GNU gettext version that
1777 corresponds at least to the AM_GNU_GETTEXT_VERSION declared
1778 in configure.ac. You can upgrade to newer GNU gettext versions,
1779 though, without needing to change configure.ac.
1781 - The -I DIR or --include=DIR option now appends DIR to the include path
1782 instead of prepending; this is for consistency with other GNU tools.
1783 The new -B DIR or --prepend-include=DIR option has the old behavior.
1788 Now handles all the gory details about LIBOBJS and LTLIBOBJS.
1789 Please, remove lines such as
1791 # This is necessary so that .o files in LIBOBJS are also
1792 # built via the ANSI2KNR-filtering rules.
1793 LIBOBJS=`echo $LIBOBJS|sed 's/\.o /\$U.o /g;s/\.o$/\$U.o/'`
1795 and read the 'AC_LIBOBJ vs LIBOBJS' section. Do not define U in
1796 your Makefiles either.
1798 - AC_CONFIG_LINKS now makes copies if it can't make links.
1800 - AC_FUNC_FNMATCH now tests only for POSIX compatibility, reverting to
1801 Autoconf 2.13 behavior. The new macro AC_FUNC_FNMATCH_GNU also
1802 tests for GNU extensions to fnmatch, and replaces fnmatch if needed.
1804 - AC_FUNC_SETVBUF_REVERSED no longer fails when cross-compiling.
1806 - AC_PROG_CC_STDC is integrated into AC_PROG_CC.
1808 - AC_PROG_F77 default search no longer includes cf77 and cfg77.
1812 AC_C_BACKSLASH_A, AC_CONFIG_LIBOBJ_DIR, AC_GNU_SOURCE,
1813 AC_PROG_EGREP, AC_PROG_FGREP, AC_REPLACE_FNMATCH,
1814 AC_FUNC_FNMATCH_GNU, AC_FUNC_REALLOC, AC_TYPE_MBSTATE_T.
1816 - AC_FUNC_GETLOADAVG
1817 looks for getloadavg.c in the CONFIG_LIBOBJ_DIR.
1820 Now defines HAVE_MALLOC to 0 if 'malloc' does not work, and asks
1821 for an AC_LIBOBJ replacement.
1825 - Spurious complaints from 'm4_bmatch' about invalid regular
1826 expressions are suppressed.
1828 - Empty top_builddirs are properly handled.
1830 - AC_CHECK_MEMBER works correctly when the member is an aggregate.
1833 Now colon in the optional path arguments are properly handled.
1835 ** Improved portability
1837 - Both Autoconf the package, and the scripts it produces, should run
1838 more reliably with Zsh. Bear in mind it is the default Bourne shell
1841 - Autoconf and the scripts it produces no longer assume the existence of
1842 the obsolescent commands egrep and fgrep.
1846 - Limitations of Make
1850 The GNATS base moved to
1851 https://bugs.gnu.org/cgi-bin/gnatsweb.pl?database=autoconf
1852 (It is no longer available, though.)
1857 Now contains the list of output variables and files (AC_SUBST,
1860 * Major changes in Autoconf 2.53
1862 Released 2002-03-08 by Akim Demaille.
1866 Perl 5.005_03 or later is required: autom4te is written in Perl and is
1867 needed by autoconf. autoheader, autoreconf, ifnames, and autoscan are
1873 Argument requirements, output variables, defined macros.
1874 - M4sugar, M4sh, Autotest
1876 - Double quoting macros
1877 AC_TRY_CPP, AC_TRY_COMPILE, AC_TRY_LINK and AC_TRY_RUN.
1879 The Autoconf manual is now distributed under the terms of the GNU FDL.
1880 - Section 'Hosts and Cross-Compilation'
1881 Explains the rationale for the 2.5x changes in the cross-compilation
1882 chain, and in the relationships between build, host, and target
1884 Emphasizes that 'cross-compilation' == '--host is given'.
1885 If you are working on compilers etc., be sure to read this section.
1886 - Section 'AC_LIBOBJ vs. LIBOBJS'
1887 Explains why assigning LIBOBJS directly is now an error.
1888 Details how to update the code.
1893 Now used instead of hard coded line numbers.
1894 This eases the comparison of 'configure's, and diminishes the
1895 pressure over control version archives.
1896 Automatic replacement for shells that don't support this feature.
1897 - New output variables
1898 @builddir@, @top_builddir@, @abs_srcdir@, @abs_top_srcdir@, @abs_builddir@,
1903 Autoconf and Autotest modes are provided.
1908 New, used by the Autoconf suite to cache and speed up most processing.
1910 Supported by autom4te, autoconf and autoheader.
1912 Replaces --autoconf-dir and --localdir in autoconf, autoheader,
1913 autoupdate, and autoreconf.
1915 No longer passes --cygnus, --foreign, --gnits, --gnu, --include-deps:
1916 automake options are to be given via AUTOMAKE_OPTIONS.
1918 Runs gettextize and libtoolize when appropriate.
1920 --m4dir is no longer supported.
1922 Now runs only in the specified directories, defaulting to '.',
1923 but understands AC_CONFIG_SUBDIRS for dependent directories.
1924 Before, it used to run on all the 'configure.ac' found in the
1926 Independent packages are properly updated.
1930 - The top level $prefix is propagated to the AC_CONFIG_SUBDIRS configures.
1932 Under the user pressure, $? is finally available. Probably a mistake.
1933 - AC_F77_LIBRARY_LDFLAGS now supports the HP/UX f90 compiler.
1934 - Precious variables accumulation
1935 config.status could stack several copies of the precious variables
1937 - AC_PATH_PROG and family.
1938 Works properly when given a literal path.
1940 Somewhere since 2.13, the result had been reversed.
1944 - AC_C_BIGENDIAN supports the cross-compiling case.
1945 - AC_C_BIGENDIAN accepts ACTION-IF-TRUE, ACTION-IF-FALSE, and
1946 ACTION-IF-UNKNOWN arguments. All are optional, and the default
1947 for ACTION-IF-TRUE is to define WORDS_BIGENDIAN like AC_C_BIGENDIAN
1949 - AC_C_LONG_DOUBLE now succeeds only if 'long double' has more range or
1950 precision than 'double'.
1955 It now defines the preprocessor symbols PACKAGE_NAME,
1956 PACKAGE_TARNAME, PACKAGE_VERSION, PACKAGE_STRING, and
1960 Admits a fourth optional parameter: the tar name.
1962 - AC_CONFIG_COMMANDS, HEADERS, FILES, LINKS.
1963 Provide the user with srcdir, ac_srcdir, ac_top_srcdir, ac_builddir,
1964 ac_top_builddir, ac_abs_srcdir, ac_abs_top_srcdir, ac_abs_builddir,
1965 ac_abs_top_builddir.
1967 - AC_CONFIG_COMMANDS, HEADERS, FILES, LINKS and AC_OUTPUT.
1968 Are much less expensive when using long lists of files.
1971 Works with shell variables, and non alphanumeric names.
1975 - AC_FUNC_STRERROR_R now sets STRERROR_R_CHAR_P, not HAVE_WORKING_STRERROR_R,
1976 because POSIX 1003.1-200x draft 7 says strerror_r returns int, not char *.
1978 - AC_FUNC_STRTOD substitutes POW_LIB.
1983 * Major changes in Autoconf 2.52
1985 Released 2001-07-18 by Akim Demaille.
1990 This feature was present in autoconf 2.50 but was not documented.
1991 For example, '@<:@' is translated to '[' just before output. This
1992 is useful when writing strings that contain unbalanced quotes, or
1993 other hard-to-quote constructs.
1994 - m4_pattern_forbid, m4_pattern_allow
1995 - Tips for upgrading from 2.13.
1996 - Using autoscan to maintain a configure.ac.
1999 - Now include stdint.h.
2000 - sys/types.h and sys/stat.h are guarded.
2001 - strings.h is included if available, and not conflicting with string.h.
2004 - The test suite is more robust and presents less false failures.
2005 - Invocation of GNU M4 now robust to POSIXLY_CORRECT.
2006 - configure accepts --prefix='' again.
2007 - AC_CHECK_LIB works properly when its first argument is not a
2009 - HAVE_INTTYPES_H is defined only if not conflicting with sys/types.h.
2010 - build_, host_, and target_alias are AC_SUBST as in 2.13.
2011 - AC_ARG_VAR properly propagates precious variables inherited from the
2012 environment to ./config.status.
2013 - Using --program-suffix/--program-prefix is portable.
2014 - Failures to detect the default compiler's output extension are less
2016 - 'config.status foo' works properly when 'foo' depends on variables
2017 set in an AC_CONFIG_THING INIT-CMD.
2018 - autoheader is more robust to broken input.
2019 - Fixed Fortran name-mangling and link tests on a number of systems,
2020 e.g. NetBSD; see AC_F77_DUMMY_MAIN, below.
2023 - AC_CHECK_HEADER and AC_CHECK_HEADERS support a fourth argument to
2024 specify pre-includes. In this case, the headers are compiled with
2025 cc, not merely preprocessed by cpp. Therefore it is the _usability_
2026 of a header which is checked for, not just its availability.
2027 - AC_ARG_VAR refuses to run configure when precious variables have
2029 - Versions of compilers are dumped in the logs.
2030 - AC_CHECK_TYPE recognizes use of 'foo_t' as a replacement type.
2033 - AC_PATH_XTRA only adds -ldnet to $LIBS if it's needed to link.
2034 - AC_FUNC_WAIT3 and AC_SYS_RESTARTABLE_SYSCALLS are obsoleted.
2035 - AM_FUNC_ERROR_AT_LINE, AM_FUNC_FNMATCH, AM_FUNC_MKTIME,
2036 AM_FUNC_OBSTACK, and AM_FUNC_STRTOD are now activated.
2037 Be sure to read 'Upgrading from Version 2.13' to understand why
2038 running 'autoupdate' is needed.
2039 - AC_F77_DUMMY_MAIN, AC_F77_MAIN: new macros to detect whether
2040 a main-like routine is required/possible when linking C/C++ with
2041 Fortran. Users of e.g. AC_F77_WRAPPERS should be aware of these.
2042 - AC_FUNC_GETPGRP behaves better when cross-compiling.
2044 * Major changes in Autoconf 2.51
2045 There was no release of Autoconf 2.51 since some packagers had used
2046 this version number without permission to ship intermediary versions
2047 of 2.50. The version was skipped to avoid confusion.
2049 * Major changes in Autoconf 2.50
2051 Released 2001-05-21 by Akim Demaille.
2053 ** Lots of bug fixes
2054 There have been far too many to enumerate them here. Check out
2055 ChangeLog if you really want to know more.
2057 ** Improved documentation
2058 In particular, portability issues are better covered.
2061 All the standard GNU Makefile targets are supported. The layout has
2062 changed: m4/ holds the M4 extensions Autoconf needs for its
2063 configuration, doc/ contains the documentation, and tests/ contains
2066 ** Man pages are provided
2067 For autoconf, autoreconf, autoupdate, autoheader, autoscan, ifnames,
2068 config.guess, config.sub.
2072 Provides a safe and powerful means to trace the macro uses. This
2073 provide the parsing layer for tools which need to 'study'
2077 Specify what category of warnings should be enabled.
2079 - When recursing into subdirectories, try for configure.gnu before
2080 configure to adapt for packages not using autoconf on case-insensitive
2084 More errors are now caught (circular AC_REQUIRE dependencies,
2085 AC_DEFINE in the action part of an AC_CACHE_CHECK, too many pops
2086 etc.). In addition, their location and call stack are given.
2089 autoupdate is much more powerful, and is able to provide the glue code
2090 which might be needed to move from an old macro to its newer
2093 You are strongly encouraged to use it to modernize both your
2094 'configure.in' and your .m4 extension files.
2097 The internal machinery of autoheader has completely changed. As a
2098 result, using 'acconfig.h' should be considered to be obsoleted, and
2099 you are encouraged to get rid of it using the AH macros.
2104 ** Fortran 77 compilers
2105 Globally, the support for Fortran 77 is considerably improved.
2107 Support for automatically determining a Fortran 77 compiler's
2108 name-mangling scheme. New CPP macros F77_FUNC and F77_FUNC_ are
2109 provided to wrap C/C++ identifiers, thus making it easier and more
2110 transparent for C/C++ to call Fortran 77 routines, and Fortran 77 to
2111 call C/C++ routines. See the Texinfo documentation for details.
2114 The test suite no longer uses DejaGNU. It should be easy to submit
2115 test cases in this new framework.
2118 - --help, --help=long, -hl
2119 no longer dumps useless items.
2121 lists only specific options.
2122 - --help=recursive, -hr
2123 displays the help of all the embedded packages.
2124 - Remembers environment variables when reconfiguring.
2125 The previous scheme to set envvar before running configure was
2127 what prevented configure from remembering the environment in which
2128 it was run, therefore --recheck was run in an inconsistent
2129 environment. Now, one should run
2131 and then --recheck will work properly. Variables declared with
2132 AC_ARG_VAR are also preserved.
2134 $build defaults to `config.guess`, $host to $build, and then $target
2136 Cross-compilation is a global status of the package, it no longer
2137 depends upon the current language.
2138 Cross compilation is enabled iff the user specified '--host'.
2139 'configure' now fails if it can't run the executables it compiles,
2140 unless cross-compilation is enabled.
2142 The cache file is disabled by default. The new options
2143 '--config-cache', '-C' set the cache to 'config.cache'.
2147 Much faster on most architectures.
2148 - concurrent executions
2149 It is safe to use 'make -j' with config.status.
2150 - human interface improved
2151 It is possible to invoke
2152 ./config.status foobar
2153 instead of the former form (still valid)
2154 CONFIG_COMMANDS= CONFIG_HEADERS= CONFIG_LINKS= \
2155 CONFIG_FILES=foobar:foo.in:bar.in \
2157 The same holds for configuration headers and links.
2158 You can instantiate unknown files and headers:
2159 ./config.status --header foo.h:foo.h.in --file bar:baz
2160 - has a useful --help
2161 - accepts special file name "-" for stdin/stdout
2166 Specify additional copyright information.
2169 Now expects the identity of the package as argument.
2173 Most macros, if not all, now strictly follow the 'one quotation
2174 level' rule. This results in a more predictable expansion.
2177 A sly bug in the AC_REQUIRE machinery, which could produce incorrect
2178 configure scripts, was fixed by Axel Thimm.
2182 Document and ask for the registration of an envvar.
2185 Specifies the file which 'configure' should look for when trying to
2186 find the source tree (used to be handled by AC_INIT).
2188 - AC_CONFIG_COMMANDS
2189 To add new actions to config.status. Should be used instead of
2193 Replaces AC_LINK_FILES.
2195 - AC_CONFIG_HEADERS, AC_CONFIG_COMMANDS, AC_CONFIG_SUBDIRS,
2196 AC_CONFIG_LINKS, and AC_CONFIG_FILES
2197 They now obey sh: you should no longer use shell variables as
2198 argument. Instead of
2200 test "$package_foo_enabled" = yes && $my_subdirs="$my_subdirs foo"
2201 AC_CONFIG_SUBDIRS($my_subdirs)
2205 if test "$package_foo_enabled" = yes; then
2206 AC_CONFIG_SUBDIRS(foo)
2210 To format an Autoconf macro's help string so that it looks pretty
2211 when the user executes 'configure --help'.
2214 ** Generic Test Macros
2216 The interface of the AC_CHECK families of macros (decl, header,
2217 type, member, func) is now uniform. They support the same set of
2220 - AC_CHECK_DECL, AC_CHECK_DECLS
2221 To check whether a symbol is declared.
2223 - AC_CHECK_SIZEOF, AC_C_CHAR_UNSIGNED.
2224 No longer need a cross-compilation default.
2227 The test it performs is much more robust than previously, and makes
2228 it possible to test builtin types in addition to typedefs.
2229 It is now schizophrenic:
2230 - AC_CHECK_TYPE(TYPE, REPLACEMENT)
2231 remains for backward compatibility, but its use is discouraged.
2232 - AC_CHECK_TYPE(TYPE, IF-FOUND, IF-NOT-FOUND, INCLUDES)
2233 behaves exactly like the other AC_CHECK macros.
2236 Checks whether given types are supported by the system.
2238 - AC_CHECK_MEMBER, AC_CHECK_MEMBERS
2239 Check for given members in aggregates (e.g., pw_gecos in struct
2243 Checks if the compiler supports ISO C, included when needs special
2247 Checking whether the preprocessor indicates missing includes by the
2248 error code. stderr is checked by AC_TRY_CPP only as a fallback.
2251 Takes a language as argument and replaces AC_LANG_C,
2252 AC_LANG_CPLUSPLUS and AC_LANG_FORTRAN77.
2254 - AC_LANG_PUSH, AC_LANG_POP
2255 Are preferred to AC_LANG_SAVE, AC_LANG_RESTORE.
2258 - AC_FUNC_CHOWN, AC_FUNC_MALLOC, AC_FUNC_STRERROR_R,
2259 AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK, AC_FUNC_STAT, AC_FUNC_LSTAT,
2260 AC_FUNC_ERROR_AT_LINE, AC_FUNC_OBSTACK, AC_FUNC_STRTOD, AC_FUNC_FSEEKO.
2264 Sets GETGROUPS_LIBS.
2266 - AC_FUNC_GETLOADAVG
2267 Defines 'HAVE_STRUCT_NLIST_N_UN_N_NAME' instead of 'NLIST_NAME_UNION'.
2270 Now integrates 'AC_DECL_YYTEXT' which is obsoleted.
2273 Arrange for large-file support.
2275 - AC_EXEEXT, AC_OBJEXT
2276 You are no longer expected to use them: their computation is
2277 performed by default.
2279 ** C++ compatibility
2280 Every macro has been revisited in order to support at best CC=c++.
2282 Major changes in Autoconf 2.14:
2283 There was no release of GNU Autoconf 2.14.
2285 Major changes in Autoconf 2.13:
2287 Released 1999-05-01 by Ben Elliston.
2289 * Support for building on 32-bit Windows systems where the only available C or
2290 C++ compiler is the Microsoft Visual C++ command line compiler
2291 ('cl'). Additional support for building on 32-bit Windows systems which are
2292 using the Cygwin or Mingw32 environments.
2293 * Support for alternative object file and executable file extensions.
2294 On 32-bit Windows, for example, these are .obj and .exe. These are discovered
2295 using AC_OBJEXT and AC_EXEEXT, which substitute @OBJEXT@ and
2296 @EXEEXT@ in the output, respectively.
2297 * New macros: AC_CACHE_LOAD, AC_CACHE_SAVE, AC_FUNC_SELECT_ARGTYPES,
2298 AC_VALIDATE_CACHED_SYSTEM_TUPLE, AC_SEARCH_LIBS, AC_TRY_LINK_FUNC,
2299 AC_C_STRINGIZE, AC_CHECK_FILE(S), AC_PROG_F77 (and friends).
2300 * AC_DEFINE now has an optional third argument for a description to be
2301 placed in the config header input file (e.g. config.h.in).
2302 * The C++ code fragment compiled for the C++ compiler test had to be
2303 improved to include an explicit return type for main(). This was
2304 causing failures on systems using recent versions of the EGCS C++
2306 * Fixed an important bug in AC_CHECK_TYPE that would cause a configure
2307 script to report that 'sometype_t' was present when only 'type_t'
2309 * Merge of the FSF version of config.guess and config.sub to modernize
2310 these scripts. Add support for a few new hosts in config.guess.
2311 Incorporate latest versions of install-sh, mkinstalldirs and
2312 texinfo.tex from the FSF.
2313 * autoreconf is capable of running automake if necessary (and
2315 * Support for Fortran 77. See the Texinfo documentation for details.
2316 * Bug fixes and workarounds for quirky bugs in vendor utilities.
2318 Major changes in Autoconf 2.12:
2320 Released 1996-11-26 by David J. MacKenzie
2322 * AC_OUTPUT and AC_CONFIG_HEADERS can create output files by
2323 concatenating multiple input files separated by colons, like so:
2324 AC_CONFIG_HEADERS([config.h:conf.pre:config.h.in:conf.post])
2325 AC_OUTPUT([Makefile:Makefile.in:Makefile.rules])
2326 The arguments may be shell variables, to compute the lists on the fly.
2327 * AC_LINK_FILES and AC_CONFIG_SUBDIRS may be called multiple times.
2328 * New macro AC_OUTPUT_COMMANDS adds more commands to run in config.status.
2331 Major changes in Autoconf 2.11:
2333 Released November 18th, 1996, by David J. MacKenzie
2335 * AC_PROG_CC and AC_PROG_CXX check whether the compiler works.
2336 They also default CFLAGS/CXXFLAGS to "-g -O2" for gcc, instead of "-g -O".
2337 * AC_REPLACE_FUNCS defines HAVE_foo if the system has the function 'foo'.
2338 * AC_CONFIG_HEADERS expands shell variables in its argument.
2339 * New macros: AC_FUNC_FNMATCH, AC_FUNC_SETPGRP.
2340 * The "checking..." messages and the source code for test programs that
2341 fail are saved in config.log.
2342 * Another workaround has been added for seds with small command length limits.
2343 * config.sub and config.guess recognize more system types.
2346 Major changes in Autoconf 2.10:
2348 Released May 7th, 1996, by Roland McGrath
2351 * The cache variable names used by 'AC_CHECK_LIB(LIB, FUNC, ...)' has
2352 changed: now $ac_cv_lib_LIB_FUNC, previously $ac_cv_lib_LIB.
2354 Major changes in Autoconf 2.9:
2356 Released March 16th, 1996, by Roland McGrath
2360 Major changes in Autoconf 2.8:
2362 Released March 8th, 1996, by Roland McGrath
2366 Major changes in Autoconf 2.7:
2368 Released November 22nd, 1995, by David J. MacKenzie
2372 Major changes in Autoconf 2.6:
2374 Released November 20th, 1995, by David J. MacKenzie
2378 Major changes in Autoconf 2.5:
2380 Released November 17th, 1995, by Roland McGrath
2382 * New configure options --bindir, --libdir, --datadir, etc., with
2383 corresponding output variables.
2384 * New macro: AC_CACHE_CHECK, to make using the cache easier.
2385 * config.log contains the command being run as well as any output from it.
2386 * AC_CHECK_LIB can check for libraries with "." or "/" or "+" in their name.
2387 * AC_PROG_INSTALL doesn't cache a name for install-sh, for sharing caches.
2388 * AC_CHECK_PROG, AC_PATH_PROG, AC_CHECK_PROGS, AC_PATH_PROGS, and
2389 AC_CHECK_TOOL can search a path other than $PATH.
2390 * AC_CHECK_SIZEOF takes an optional size to use when cross-compiling.
2392 Major changes in Autoconf 2.4:
2394 Released June 14th, 1995, by David J. MacKenzie
2396 * Fix a few bugs found by Emacs testers.
2398 Major changes in Autoconf 2.3:
2400 Released March 27th, 1995, by David J. MacKenzie
2402 * Fix the cleanup trap in several ways.
2403 * Handle C compilers that are picky about option placement.
2404 * ifnames gets the version number from the right directory.
2406 Major changes in Autoconf 2.2:
2408 Released March 8th, 1995, by David J. MacKenzie
2410 * The ifnames utility is much faster but requires a "new awk" interpreter.
2411 * AC_CHECK_LIB and AC_HAVE_LIBRARY check and add the new
2412 library before existing libs, not after, in case it uses them.
2413 * New macros: AC_FUNC_GETPGRP, AC_CHECK_TOOL.
2414 * Lots of bug fixes.
2415 * Many additions to the TODO file :-)
2417 Major changes in Autoconf 2.1:
2419 Released November 4th, 1994, by David J. MacKenzie
2422 * More explanations in the manual.
2423 * Fix a spurious failure in the testsuite.
2424 * Clarify some warning messages.
2425 * autoreconf by default only rebuilds configure and config.h.in files
2426 that are older than any of their particular input files; there is a
2427 --force option to use after installing a new version of Autoconf.
2429 Thanks to everybody who's submitted changes and additions to Autoconf!
2430 I've incorporated many of them, and am still considering others for
2431 future releases -- but I didn't want to postpone this release indefinitely.
2433 Caution: don't indiscriminately rebuild configure scripts with
2434 Autoconf version 2. Some configure.in files need minor adjustments to
2435 work with it; the documentation has a chapter on upgrading. A few
2436 configure.in files, including those for GNU Emacs and the GNU C
2437 Library, need major changes because they relied on undocumented
2438 internals of version 1. Future releases of those packages will have
2439 updated configure.in files.
2441 It's best to use GNU M4 1.3 (or later) with Autoconf version 2.
2442 Autoconf now makes heavy use of M4 diversions, which were implemented
2443 inefficiently in GNU M4 releases before 1.3.
2445 Major changes in Autoconf 2.0:
2447 Released October 26th, 1994, by David J. MacKenzie
2449 ** New copyright terms:
2450 * There are no restrictions on distribution or use of configure scripts.
2453 * Autoconf manual is reorganized to make information easier to find
2454 and has several new indexes.
2455 * INSTALL is reorganized and clearer and is now made from Texinfo source.
2458 * autoscan to generate a preliminary configure.in for a package by
2459 scanning its source code for commonly used nonportable functions,
2460 programs, and header files.
2461 * ifnames to list the symbols used in #if and #ifdef directives in a
2463 * autoupdate to update a configure.in to use the version 2 macro names.
2464 * autoreconf to recursively remake configure and configuration header
2465 files in a source tree.
2467 ** Changed utilities:
2468 * autoheader can take pieces of acconfig.h to replace config.h.{top,bot}.
2469 * autoconf and autoheader can look for package-local definition files
2470 in an alternate directory.
2473 * AC_CACHE_VAL to share results of tests between configure runs.
2474 * AC_DEFUN to define macros, automatically AC_PROVIDE them, and ensure
2475 that macros invoked with AC_REQUIRE don't interrupt other macros.
2476 * AC_CONFIG_AUX_DIR, AC_CANONICAL_SYSTEM, AC_CANONICAL_HOST, AC_LINK_FILES to
2477 support deciding unguessable features based on the host and target types.
2478 * AC_CONFIG_SUBDIRS to recursively configure a source tree.
2479 * AC_ARG_PROGRAM to use the options --program-prefix,
2480 --program-suffix, and --program-transform-name to change the names
2481 of programs being installed.
2482 * AC_PREFIX_DEFAULT to change the default installation prefix.
2483 * AC_TRY_COMPILE to compile a test program without linking it.
2484 * AC_CHECK_TYPE to check whether sys/types.h or stdlib.h defines a given type.
2485 * AC_CHECK_LIB to check for a particular function and library.
2486 * AC_MSG_CHECKING and AC_MSG_RESULT to print test results, on a single line,
2487 whether or not the test succeeds. They obsolete AC_CHECKING and AC_VERBOSE.
2488 * AC_SUBST_FILE to insert one file into another.
2489 * AC_FUNC_MEMCMP to check whether memcmp is 8-bit clean.
2490 * AC_FUNC_STRFTIME to find strftime even if it's in -lintl.
2491 * AC_FUNC_GETMNTENT to find getmntent even if it's in -lsun or -lseq.
2492 * AC_HEADER_SYS_WAIT to check whether sys/wait.h is POSIX.1 compatible.
2495 * Many macros renamed systematically, but old names are accepted for
2496 backward compatibility.
2497 * AC_OUTPUT adds the "automatically generated" comment to
2498 non-Makefiles where it finds @configure_input@ in an input file, to
2499 support files with various comment syntaxes.
2500 * AC_OUTPUT does not replace "prefix" and "exec_prefix" in generated
2501 files when they are not enclosed in @ signs.
2502 * AC_OUTPUT allows the optional environment variable CONFIG_STATUS to
2503 override the file name "config.status".
2504 * AC_OUTPUT takes an optional argument for passing variables from
2505 configure to config.status.
2506 * AC_OUTPUT and AC_CONFIG_HEADERS allow you to override the input-file names.
2507 * AC_OUTPUT automatically substitutes the values of CFLAGS, CXXFLAGS,
2508 CPPFLAGS, and LDFLAGS from the environment.
2509 * AC_PROG_CC and AC_PROG_CXX now set CFLAGS and CXXFLAGS, respectively.
2510 * AC_PROG_INSTALL looks for install-sh or install.sh in the directory
2511 specified by AC_CONFIG_AUXDIR, or srcdir or srcdir/.. or
2512 srcdir/../.. by default.
2513 * AC_DEFINE, AC_DEFINE_UNQUOTED, and AC_SUBST are more robust and smaller.
2514 * AC_DEFINE no longer prints anything, because of the new result reporting
2515 mechanism (AC_MSG_CHECKING and AC_MSG_RESULT).
2516 * AC_VERBOSE pays attention to --quiet/--silent, not --verbose.
2517 * AC_ARG_ENABLE and AC_ARG_WITH support whitespace in the arguments to
2518 --enable- and --with- options.
2519 * AC_CHECK_FUNCS and AC_CHECK_HEADERS take optional shell commands to
2520 execute on success or failure.
2521 * Checking for C functions in C++ works.
2524 * AC_REMOTE_TAPE and AC_RSH removed; too specific to tar and cpio, and
2525 better maintained with them.
2526 * AC_ARG_ARRAY removed because no one was likely using it.
2527 * AC_HAVE_POUNDBANG replaced with AC_SYS_INTERPRETER, which doesn't
2528 take arguments, for consistency with all of the other specific checks.
2531 * Comes with config.sub and config.guess, and uses them optionally.
2532 * Uses config.cache to cache test results. An alternate cache file
2533 can be selected with the --cache-file=FILE option.
2534 * Uses optional shell scripts $prefix/share/config.site and
2535 $prefix/etc/config.site to perform site or system specific initializations.
2536 * configure saves compiler output to ./config.log for debugging.
2537 * New files autoconf.m4 and autoheader.m4 load the other Autoconf macros.
2538 * acsite.m4 is the new name for the system-wide aclocal.m4.
2539 * Has a DejaGnu test suite.
2541 Major changes in Autoconf 1.11:
2543 * AC_PROG_INSTALL calls install.sh with the -c option.
2544 * AC_SET_MAKE cleans up after itself.
2545 * AC_OUTPUT sets prefix and exec_prefix if they weren't set already.
2546 * AC_OUTPUT prevents shells from looking in PATH for config.status.
2548 Plus a few other bug fixes.
2550 Major changes in Autoconf 1.10:
2552 * autoheader uses config.h.bot if present, analogous to config.h.top.
2553 * AC_PROG_INSTALL looks for install.sh in srcdir or srcdir/.. and
2555 * AC_PROG_CXX looks for cxx as a C++ compiler.
2557 Plus several bugs fixed.
2559 Major changes in Autoconf 1.9:
2561 * AC_YYTEXT_POINTER replaces AC_DECLARE_YYTEXT.
2562 * AC_SIZEOF_TYPE generates the cpp symbol name automatically,
2563 and autoheader generates entries for those names automatically.
2564 * AC_FIND_X gets the result from xmkmf correctly.
2565 * AC_FIND_X assumes no X if --without-x was given.
2566 * AC_FIND_XTRA adds libraries to the variable X_EXTRA_LIBS.
2567 * AC_PROG_INSTALL finds OSF/1 installbsd.
2569 Major changes in Autoconf 1.8:
2572 * New macros AC_LANG_C, AC_LANG_CPLUSPLUS, AC_LANG_SAVE, AC_LANG_RESTORE,
2573 AC_PROG_CXX, AC_PROG_CXXCPP, AC_REQUIRE_CPP
2574 for checking both C++ and C features in one configure script.
2575 * New macros AC_CHECKING, AC_VERBOSE, AC_WARN, AC_ERROR for printing messages.
2576 * New macros AC_FIND_XTRA, AC_MMAP, AC_SIZEOF_TYPE, AC_PREREQ,
2577 AC_SET_MAKE, AC_ENABLE.
2580 * AC_FIND_X looks for X in more places.
2581 * AC_PROG_INSTALL defaults to install.sh instead of cp, if it's in srcdir.
2582 install.sh is distributed with Autoconf.
2583 * AC_DECLARE_YYTEXT has been removed because it can't work, pending
2584 a rewrite of quoting in AC_DEFINE.
2585 * AC_OUTPUT adds its comments in C format when substituting in C files.
2586 * AC_COMPILE_CHECK protects its ECHO-TEXT argument with double quotes.
2588 ** New or changed command line options:
2589 * configure accepts --enable-FEATURE[=ARG] and --disable-FEATURE options.
2590 * configure accepts --without-PACKAGE, which sets withval=no.
2591 * configure accepts --x-includes=DIR and --x-libraries=DIR.
2592 * Giving --with-PACKAGE no argument sets withval=yes instead of withval=1.
2593 * configure accepts --help, --version, --silent/--quiet, --no-create options.
2594 * configure accepts and ignores most other Cygnus configure options, and
2595 warns about unknown options.
2596 * config.status accepts --help, --version options.
2598 ** File names and other changes:
2599 * Relative srcdir values are not made absolute.
2600 * The values of @prefix@ and @exec_prefix@ and @top_srcdir@ get substituted.
2601 * Autoconf library files are installed in ${datadir}/autoconf, not ${datadir}.
2602 * autoheader optionally copies config.h.top to the beginning of config.h.in.
2603 * The example Makefile dependencies for configure et al. work better.
2604 * Namespace cleanup: all shell variables used internally by Autoconf
2605 have names beginning with 'ac_'.
2607 More big improvements are in process for future releases, but have not
2608 yet been (variously) finished, integrated, tested, or documented enough
2611 Major changes in Autoconf 1.7:
2613 * New macro AC_OBSOLETE.
2614 * Bugs in Makefile.in fixed.
2615 * AC_LONG_FILE_NAMES improved.
2617 Major changes in Autoconf 1.6:
2619 * New macro AC_LONG_64_BITS.
2620 * Multiple .h files can be created.
2621 * AC_FIND_X looks for X files directly if it doesn't find xmkmf.
2622 * AC_ALLOCA defines C_ALLOCA if using alloca.c.
2623 * --with-NAME can take a value, e.g., --with-targets=sun4,hp300bsd.
2624 * Unused --no-create option to configure removed.
2625 * autoheader doesn't change the timestamp of its output file if
2626 the file didn't change.
2627 * All macros that look for libraries now use AC_HAVE_LIBRARY.
2628 * config.status checks three optional environment variables to
2629 modify its behavior.
2630 * The usual bug fixes.
2632 Major changes in Autoconf 1.5:
2634 * New macros AC_FIND_X, AC_OFF_T, AC_STAT_MACROS_BROKEN, AC_REVISION.
2635 * autoconf and autoheader scripts have GNU standards conforming
2636 --version and --help options (they print their message and exit).
2639 Major changes in Autoconf 1.4:
2641 * New macros AC_HAVE_POUNDBANG, AC_TIME_WITH_SYS_TIME, AC_LONG_DOUBLE,
2642 AC_GETGROUPS_T, AC_DEFINE_UNQUOTED.
2643 * autoconf and autoheader use the M4 environment variable to determine the
2644 name of the M4 program to use.
2645 * The --macrodir option to autoconf and autoheader specifies the directory
2646 in which acspecific.m4, acgeneral.m4, etc. reside if not the default.
2647 * autoconf and autoheader can take '-' as their file names, which means to
2648 read stdin as input.
2649 * Resulting configure scripts can take a --verbose option which causes them
2650 to print the results of their tests.
2651 * AC_DEFINE quotes its second argument in such a way that spaces, magic
2652 shell characters, etc. will be preserved during various stages of
2653 expansion done by the shell. If you don't want this, use
2654 AC_DEFINE_UNQUOTED instead.
2655 * Much textual processing done with external calls to tr and sed have been
2656 internalized with builtin M4 'patsubst' and 'translit' calls.
2657 * AC_OUTPUT doesn't hardwire the file names it outputs. Instead, you can
2658 set the shell variables 'gen_files' and 'gen_config' to the list of
2659 file names to output.
2660 * AC_DECLARE_YYTEXT does an AC_SUBST of 'LEX_OUTPUT_ROOT', which may be
2661 "lex.yy" or "lexyy", depending on the system.
2662 * AC_PROGRAMS_CHECK takes an optional third arg. If given, it is used as
2664 * If AC_ALLOCA chooses alloca.c, it also defines STACK_DIRECTION.
2665 * AC_CONST works much more reliably on more systems.
2668 Major changes in Autoconf 1.3:
2670 configure no longer requires awk for packages that use a config.h.
2671 Support handling --with-PACKAGE options.
2672 New 'autoheader' script to create 'config.h.in' from 'configure.in'.
2673 Ignore troublesome -lucb and -lPW when searching for alloca.
2674 Rename --exec_prefix to --exec-prefix for GNU standards conformance.
2675 Improve detection of STDC library.
2676 Add AC_HAVE_LIBRARY to check for non-default libraries.
2677 Function checking should work with future GNU libc releases.
2679 Major changes in Autoconf 1.2:
2681 The --srcdir option is now usually unnecessary.
2682 Add a file containing sample comments describing CPP macros.
2683 A comment in config.status tells which host it was configured on.
2684 Substituted variable values can now contain commas.
2685 Fix bugs in various feature checks.
2687 Major changes in Autoconf 1.1:
2689 Added AC_STRCOLL macro.
2690 Made AC_GETLOADAVG check for more things.
2691 AC_OUTPUT argument is now optional.
2696 Copyright (C) 1993-1996, 1998-2017, 2020-2023 Free Software Foundation,
2699 Copying and distribution of this file, with or without modification,
2700 are permitted in any medium without royalty provided the copyright
2701 notice and this notice are preserved. This file is offered as-is,
2702 without warranty of any kind.