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NEWS
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GNU Autoconf NEWS - User visible changes.
* Noteworthy changes in release ?.? (????-??-??) [?]
** Backward incompatibilities
** New features
** Obsolete features and new warnings
** Notable bug fixes
* Noteworthy changes in release 2.71 (2021-01-28) [stable]
** Bug fixes, including:
*** Compilers that support C99 but not C2011 are detected correctly.
*** Compatibility improved with clang and Oracle C++.
*** Compatibility restored with automake's rules for regenerating configure.
*** Compatibility restored with old versions of std-gnu11.m4.
Packages that wish to maintain compatibility with Autoconf 2.69 or
older, should update their copy of std-gnu11.m4 from Gnulib as soon
as practical, as the compatibility code bulks up the configure script.
Packages that require Autoconf 2.70 can drop this file entirely.
* Noteworthy changes in release 2.70 (2020-12-08) [stable]
** Backward incompatibilities:
*** Warnings about obsolete constructs are now on by default.
These warnings can be turned off with ‘-Wno-obsolete’.
Many of these warnings advise maintainers to run autoupdate.
Be aware that autoupdate cannot solve all backward compatibility
problems, and cannot completely solve all of the problems it does
address. A configure script edited by autoupdate is likely to
need further manual fix-ups.
*** Many macros have become pickier about argument quotation.
If you get a shell syntax error from your generated configure
script, or seemingly impossible misbehavior (e.g. entire blocks of
the configure script not getting executed), check first that all
macro arguments are properly quoted. The “M4 Quotation” section of
the manual explains how to quote macro arguments properly.
It is unfortunately not possible for autoupdate to correct
quotation errors.
*** Many macros no longer AC_REQUIRE as many other macros as they used to.
This can expose several classes of latent bugs. These are the ones
we know about:
- Make sure to explicitly invoke all of the macros that set result
variables used later in the configure script, or in generated
Makefiles.
- Autoconf macros that use AC_REQUIRE are not safe to use in shell
control-flow constructs that appear outside of macros defined by
AC_DEFUN. Use AS_IF, AS_CASE, etc. instead. (See the
“Prerequisite Macros” section of the manual for details.)
The set of macros that use AC_REQUIRE internally may change from
release to release. The only macros that are guaranteed *not* to
use AC_REQUIRE are the macros for acting on the results of a
test: AC_DEFINE, AC_SUBST, AC_MSG_*, AC_CACHE_CHECK, etc.
- AC_REQUIRE cannot be applied to macros that need to be used with
arguments. Instead, invoke the macro normally, with its arguments.
*** More macros use config.sub and config.guess internally.
As a consequence of improved support for cross compilation (see below),
more macros now use the auxiliary scripts ‘config.sub’ and ‘config.guess’.
If you use any of the affected macros, these scripts must be available
when your configure script is run, even if you have no intention of
ever cross-compiling your program.
autoreconf will issue an error if any auxiliary scripts are needed but
cannot be found. (It is not currently possible to make autoconf
itself issue this error.)
‘autoreconf --install’ will add ‘config.sub’, ‘config.guess’, and
‘install-sh’ to your source tree if they are needed. If you are
using Automake, scripts added to your tree by ‘autoreconf --install’
will automatically be included in the tarball produced by ‘make dist’;
otherwise, you will need to arrange for them to be distributed
yourself.
See the “Input” section of the manual for more detail, including
where to get the auxiliary scripts that may be needed by autoconf macros.
*** Setting CC to a C++ compiler is no longer supported.
The C and C++ languages have diverged enough that we can no longer
guarantee that test C programs will be processed as intended by a
C++ compiler. In this release, configure will proceed anyway, but
many test results will be incorrect. In a future release, we may
make AC_PROG_CC error out if it detects that CC is a C++ compiler.
See the “Language Choice” section of the manual for instructions on
how to write configure scripts for C++ programs, and for programs
with code in more than one language.
*** Running configure tests with warnings promoted to errors is not supported.
For instance, setting ‘CC="gcc -Werror"’ on the configure command
line, or adding -Werror to CFLAGS early in the configure script when
the compiler recognizes this option, is very likely to cause
subsequent tests to fail.
This has never been guaranteed to work; the code generated by
AC_CHECK_FUNC, for instance, is incorrect by a strict reading of the
original 1989 C standard, and has been ever since that macro was
introduced. Problems are more likely with newer, pickier compilers.
To enable compiler warnings and/or warnings-as-errors mode for your
own code, we currently recommend a dedicated Makefile variable
(e.g. ‘WARN_CFLAGS’) that is set by AC_SUBST when appropriate.
The Gnulib ‘warnings’ and ‘manywarnings’ modules can help with this.
We plan to add core support for probing for useful sets of compiler
warnings in a future release.
*** Including confdefs.h manually may cause test failures.
This has never been necessary; confdefs.h is automatically included
at the beginning of all test programs (by AC_LANG_SOURCE). Because
of the way confdefs.h is generated and used, it is not practical to
give it a multiple inclusion guard. Therefore, if you include it
yourself, all of its definitions will be scanned twice.
Historically this has not been a problem, because confdefs.h only
makes macro definitions, and the C standard allows redefinitions
of macros as long as they’re exactly the same, but newer, pickier
compilers may complain anyway (see for instance GCC bug 97998).
*** Older versions of automake and aclocal (< 1.8) are no longer supported.
*** AC_CONFIG_SUBDIRS no longer directly supports Cygnus configure.
If you are still using an Autoconf script to drive configuration of
a multi-package build tree where some subdirectories use Cygnus
configure, copy or link $ac_aux_dir/configure into each subdirectory
where it is needed. Please also contact us; we were under the
impression nobody used this very old tool anymore.
*** AC_CHECK_HEADER and AC_CHECK_HEADERS only do a compilation test.
This completes the transition from preprocessor-based header tests
begun in Autoconf 2.56.
The double test that was the default since Autoconf 2.64 is no
longer available. You can still request a preprocessor-only test
by specifying [-] as the fourth argument to either macro, but this
is now deprecated. If you really need that behavior use
AC_PREPROC_IFELSE.
*** AC_INCLUDES_DEFAULT assumes an ISO C90 compliant C implementation.
Specifically, it assumes that the ISO C90 header <stddef.h>
is available, without checking for it, and it does not include
the pre-standard header <memory.h> at all. If the POSIX header
<strings.h> exists, it will be included, without first testing
whether both <string.h> and <strings.h> can be included in the
same source file.
AC_INCLUDES_DEFAULT still checks for the existence of <stdlib.h>,
<string.h>, and <stdio.h>, because these headers may not exist
in a “freestanding environment” (a compilation mode intended for OS
kernels and similar, where most of the features of the C library are
optional). Most programs need not use ‘#ifdef HAVE_STDLIB_H’ etc in
their own code.
For compatibility’s sake, the C preprocessor macro STDC_HEADERS
will be defined when both <stdlib.h> and <string.h> are available;
however, <stdarg.h> and <float.h> are no longer checked for
(these, like <stddef.h>, are required to exist in a freestanding
environment). New code should not refer to this macro.
Future releases of Autoconf may reduce the set of headers checked
for by AC_INCLUDES_DEFAULT.
*** AS_ECHO and AS_ECHO_N unconditionally use ‘printf’.
This is substantially simpler, more reliable, and, in most cases,
faster than attempting to use ‘echo’ at all. However, if ‘printf’
is not a shell builtin, configure scripts will run noticeably
slower, and if ‘printf’ is not available at all, they will crash.
The only systems where this is known to be a problem are extremely
old, and unlikely to be able to handle modern C programs for other
reasons (e.g. not having a C90-compliant compiler at all).
*** Configure scripts require support for $( ... ) command substitution.
This POSIX shell feature is approximately the same age as
user-defined functions, but there do exist shells that support
functions and not $( ... ), such as Solaris 10 /bin/sh.
Configure scripts will automatically locate a shell that supports
this feature and re-execute themselves with it, if necessary, so
the new requirement should be transparent to most users.
In this release, most of Autoconf’s code still uses the older `...`
notation for command substitution.
*** AC_INIT now trims extra white space from its arguments.
For instance, AC_INIT([ GNU Hello ], [1.0]) will set PACKAGE_NAME
to “GNU Hello”.
*** Macros that take whitespace-separated lists as arguments
now always expand macros within those arguments.
Formerly, these macros would *usually* expand those arguments, but
the behavior was not reliable nor was it consistent between autoconf
and autoheader.
Macro expansion within these arguments is deprecated; if expansion
changes the list, a warning in the “obsolete” category will be
emitted. Note that ‘dnl’ is a macro. Putting ‘dnl’ comments inside
any argument to an Autoconf macro is, in general, only supported
when that argument takes more Autoconf code (e.g. the ACTION-IF-TRUE
argument to AC_COMPILE_IFELSE).
The affected macros are AC_CHECK_FILES, AC_CHECK_FUNCS,
AC_CHECK_FUNCS_ONCE, AC_CHECK_HEADERS, AC_CHECK_HEADERS_ONCE,
AC_CONFIG_MACRO_DIRS, AC_CONFIG_SUBDIRS, and AC_REPLACE_FUNCS.
*** AC_FUNC_VFORK no longer ignores a signal-handling bug in Solaris 2.4.
This bug was being ignored because Emacs wanted to use ‘vfork’ on
Solaris 2.4 anyway, but current versions of Emacs have dropped
support for Solaris 2.4. Most programs will want to avoid ‘vfork’
on this OS because of this bug.
*** AC_FUNC_STRERROR_R assumes strerror_r is unavailable if it’s not declared.
The fallback technique it used to probe strerror_r’s return type
when the function was present in the C library, but not declared by
<string.h>, was fragile and did not work at all when cross-compiling.
The systems where this fallback was necessary were all obsolete.
Programs that use AC_FUNC_STRERROR_R should make sure to test the
preprocessor macro HAVE_DECL_STRERROR_R before using strerror_r at all.
*** AC_OPENMP can’t be used if you have files named ‘mp’ or ‘penmp’.
Autoconf will now issue an error if AC_OPENMP is used in a configure
script that’s in the same directory as a file named ‘mp’ or ‘penmp’.
Configure scripts that use AC_OPENMP will now error out upon
encountering files with these names in their working directory
(e.g. when the build directory is separate from the source directory).
If you have files with these names at the top level of your source
tree, we recommend either renaming them or moving them into a
subdirectory. See the documentation of AC_OPENMP for further
explanation.
** New features
*** Configure scripts now support a ‘--runstatedir’ option.
This defaults to ‘${localstatedir}/run’. It can be used, for
instance, to place per-process temporary runtime files (such as pid
files) into ‘/run’ instead of ‘/var/run’.
*** autoreconf will now run gtkdocize and intltoolize when appropriate.
*** autoreconf now recognizes AM_GNU_GETTEXT_REQUIRE_VERSION.
This macro can be used with gettext 0.19.6 or later to specify
a *minimum* version requirement for gettext, instead of the *fixed*
version requirement specified by AM_GNU_GETTEXT_VERSION.
*** autoheader handles secondary config headers better.
It is no longer necessary to duplicate AC_DEFINE templates in the
main configuration header for autoheader to notice them.
*** AC_PROG_CC now enables C2011 mode if the compiler supports it.
If not, it will fall back to C99 and C89, as before. Similarly,
AC_PROG_CXX now enables C++2011 if available, falling back on C++98.
*** New macro AC_C__GENERIC tests for C2011 _Generic support.
*** AC_C_VARARRAYS has been aligned with C2011.
It now defines __STDC_NO_VLA__ if variable-length arrays are not
supported but the compiler does not define __STDC_NO_VLA__.
For backward compatibility with Autoconf 2.61-2.69 AC_C_VARARRAYS
still defines HAVE_C_VARARRAYS, but this result macro is obsolescent.
*** New macro AC_CONFIG_MACRO_DIRS.
This macro can be used more than once and accepts a list of
directories to search for local M4 macros. With Automake 1.13 and
later, use of this macro eliminates a reason to use ACLOCAL_AMFLAGS
in Makefile.am.
The older AC_CONFIG_MACRO_DIR, which could only be used once, is
still supported but considered deprecated.
*** AC_USE_SYSTEM_EXTENSIONS knows about more extensions to enable.
System extensions will now be enabled on HP-UX, macOS, and MINIX.
Optional ISO C library components (e.g. decimal floating point) will
also be enabled.
*** New compatibility macro AC_CHECK_INCLUDES_DEFAULT.
This macro runs the checks normally performed as a side-effect by
AC_INCLUDES_DEFAULT, if they haven’t already been done. Autoupdate
will replace certain obsolete constructs, whose only remaining
useful effect is to trigger those checks, with this macro. It is
unlikely to be useful otherwise.
*** AC_REQUIRE_AUX_FILE has been improved.
Configure scripts now check, on startup, for the availability of all
the aux files that were mentioned in an AC_REQUIRE_AUX_FILE
invocation. This should help prevent certain classes of packaging
errors.
Also, it is no longer necessary for third-party macros that use
AC_REQUIRE_AUX_FILE to mention AC_CONFIG_AUX_DIR_DEFAULT. However,
if you are using AC_CONFIG_AUX_DIR_DEFAULT *without* also using
AC_REQUIRE_AUX_FILE, please start using AC_REQUIRE_AUX_FILE to
specify the aux files you actually need, so that the check can be
effective.
*** AC_PROG_LEX has an option to not look for yywrap.
AC_PROG_LEX now takes one argument, which may be either ‘yywrap’ or
‘noyywrap’. If it is ‘noyywrap’, AC_PROG_LEX will only set LEXLIB
to ‘-lfl’ or ‘-ll’ if a scanner that defines both main and yywrap
itself still needs something else from that library. On the other
hand, if it is ‘yywrap’, AC_PROG_LEX will fail (setting LEX to ‘:’
and LEXLIB to nothing) if it can’t find a library that defines yywrap.
In the absence of arguments, AC_PROG_LEX’s behavior is bug-compatible
with 2.69, which did neither of the above things (see the manual for
details). This mode is deprecated.
We encourage all programs that use AC_PROG_LEX to use the new
‘noyywrap’ mode, and to define yywrap themselves, or use %noyywrap.
The yywrap function in lib(f)l is trivial, and self-contained
scanners are easier to work with.
** Obsolete features and new warnings
*** Use of the long-deprecated name ‘configure.in’ for the autoconf
input file now elicits a warning in the “obsolete” category.
*** Use of the undocumented internal shell variables $as_echo and
$as_echo_n now elicits a warning in the “obsolete” category.
The macros AS_ECHO and AS_ECHO_N should be used instead.
*** autoconf will now issue warnings (in the “syntax” category)
if the input file is missing a call to AC_INIT and/or AC_OUTPUT.
*** autoconf will now issue warnings (in the “syntax” category)
for a non-literal URL argument to AC_INIT, and for a TARNAME
argument to AC_INIT which is either non-literal or contains
characters that should not be used in file names (e.g. ‘*’).
*** AC_PROG_CC_STDC, AC_PROG_CC_C89, AC_PROG_CC_C99 are now obsolete.
Applications should use AC_PROG_CC.
*** AC_HEADER_STDC and AC_HEADER_TIME are now stubs.
They still define the C preprocessor macros STDC_HEADERS and
TIME_WITH_SYS_TIME, respectively, but they no longer check for the
ancient, non-ISO-C90 compliant systems where formerly those macros
would not be defined. Autoupdate will remove them.
These macros were already labeled obsolete in the manual.
*** AC_DIAGNOSE, AC_FATAL, AC_WARNING, and _AC_COMPUTE_INT are now
replaced with modern equivalents by autoupdate.
These macros were already labeled obsolete in the manual.
*** AC_CONFIG_HEADER is now diagnosed as obsolete, and replaced with
AC_CONFIG_HEADERS by autoupdate.
This macro has been considered obsolete for many years and was not
documented at all.
*** The macro AC_OBSOLETE is obsolete.
Autoupdate will replace it with m4_warn([obsolete], [explanation]).
If possible, macros using AC_OBSOLETE should be converted to use
AU_DEFUN or AU_ALIAS instead, which enables autoupdate to replace
them, but this has to be done by hand and is not always possible.
This macro has been considered obsolete for many years, but was not
officially declared as such.
*** Man pages for config.guess and config.sub are no longer provided.
They were moved to the master source tree for config.guess and
config.sub.
** Notable bug fixes
*** Compatible with current Automake, Libtool, Perl, Texinfo, and shells.
All of autoconf’s tools and generated scripts, and the build process
and testsuite for autoconf itself, have been tested to work
correctly with current versions of Automake, Libtool, Perl, Texinfo,
bash, ksh93, zsh, and FreeBSD and NetBSD /bin/sh.
Generated configure scripts are expected to work reliably with an
even wider variety of shells, including BusyBox sh and various
proprietary Unixes’ /bin/sh, as long as they are minimally compliant
with the Unix95 shell specification. Notably, support for
shell-script functions and the ‘printf’ builtin are required.
*** Checks compatible with current language standards and compilers.
Many individual macros have been improved to accommodate changes in
recent versions of the C and C++ language standards, and new
features and quirks of commonly used compilers (both free and
proprietary).
*** Improved support for cross compilation.
Many individual macros have been improved to produce more accurate
results when cross-compiling.
*** Improved robustness against unusual build environments.
Many bugs have been fixed where generated configure scripts would
fail catastrophically under unusual conditions, such as stdout being
closed, or $TMPDIR not being an absolute path, or the root directory
being mentioned in $PATH.
*** AC_CHECK_FUNCS_ONCE and AC_CHECK_HEADERS_ONCE now support multiple
programming languages. They no longer perform all checks in the
language active upon the first use of the macro.
*** AC_CHECK_DECL and AC_CHECK_DECLS will now detect missing declarations for
library functions that are also Clang compiler builtins.
*** AC_PATH_X and AC_PATH_XTRA don’t search for X11 when cross-compiling.
Libraries and headers found by running xmkmf or searching /usr/X11,
/usr/X11R7, etc. are likely to belong to a native X11 installation
for the build machine and to be inappropriate for cross compilation.
To cross-compile programs that require X11, we recommend putting the
headers and libraries for the host system in your cross-compiler’s
default search paths. Alternatively, use configure’s --x-includes
and --x-libraries command line options to tell it where they are.
*** AS_IF’s if-false argument may be empty after macro expansion.
This long-standing limitation broke configure scripts that used
macros in this position that emitted shell code in 2.69 but no
longer do, so we have lifted it.
*** AC_HEADER_MAJOR detects the location of the major, minor, and
makedev macros correctly under glibc 2.25 and later.
*** AC_FC_LINE_LENGTH now documents the maximum portable length of
“unlimited” Fortran source code lines to be 250 columns, not 254.
*** AC_INIT and AS_INIT no longer embed (part of) the path to the
source directory in generated files.
We believe this was the only case where generated file contents
could change depending on the environment outside the source tree
itself. If you find any other cases please report them as bugs.
*** config.log properly escapes arguments in the header comment.
*** config.status --config output is now quoted in a more readable fashion.
** Autotest enhancements
*** Autotest provides a new macro AT_DATA_UNQUOTED, similar to AT_DATA
but processing variable substitutions, command substitutions and
backslashes in the contents argument.
*** AC_CONFIG_TESTDIR will automatically pass EXEEXT to a testsuite (via
the atconfig file).
*** AT_TESTED arguments can use variable or command substitutions, including
in particular $EXEEXT
*** New macros AT_PREPARE_TESTS, AT_PREPARE_EACH_TEST, and AT_TEST_HELPER_FN.
These provide an official way to define testsuite-specific
initialization code and shell functions.
* Noteworthy changes in release 2.69 (2012-04-24) [stable]
** Autoconf now requires perl 5.6 or better (but generated configure
scripts continue to run without perl).
* Noteworthy changes in release 2.68b (2012-03-01) [beta]
Released by Eric Blake, based on git versions 2.68.*.
** Autoconf-generated configure scripts now unconditionally re-execute
themselves with $CONFIG_SHELL, if that's set in the environment.
** The texinfo documentation no longer specifies "front-cover" or
"back-cover" texts, so that it may now be included in Debian's
"main" section.
** Support for the Go programming language has been added. The new macro
AC_LANG_GO sets variables GOC and GOFLAGS.
** AS_LITERAL_IF again treats '=' as a literal. Regression introduced in
2.66.
** The macro AS_EXECUTABLE_P, present since 2.50, is now documented.
** Macros
- AC_PROG_LN_S and AS_LN_S now fall back on 'cp -pR' (not 'cp -p') if 'ln -s'
does not work. This works better for symlinks to directories.
- New macro AC_HEADER_CHECK_STDBOOL.
- New and updated macros for Fortran support:
AC_FC_CHECK_BOUNDS to enable array bounds checking
AC_F77_IMPLICIT_NONE and AC_FC_IMPLICIT_NONE to disable implicit integer
AC_FC_MODULE_EXTENSION to compute the Fortran 90 module name extension
AC_FC_MODULE_FLAG for the Fortran 90 module search path flag
AC_FC_MODULE_OUTPUT_FLAG for the Fortran 90 module output directory flag
AC_FC_PP_SRCEXT for preprocessed Fortran source files extensions
AC_FC_PP_DEFINE for the Fortran preprocessor define flag
* Noteworthy changes in release 2.68 (2010-09-22) [stable]
Released by Eric Blake, based on git versions 2.67.*.
** AC_MSG_ERROR (and AS_ERROR) can once again be followed immediately by
`dnl'. Regression introduced in 2.66.
** AC_INIT again allows URLs with '?' for its BUG-REPORT argument.
Regression introduced in 2.66.
** AC_REPLACE_FUNCS again allows a non-literal argument, such as a shell
variable that expands to a list of functions to check. Regression
introduced in 2.66.
** AT_BANNER() with empty argument will cause visual separation from previous
test category.
** The macros AC_PREPROC_IFELSE, AC_COMPILE_IFELSE, AC_LINK_IFELSE, and
AC_RUN_IFELSE now warn if the first argument failed to use
AC_LANG_SOURCE or AC_LANG_PROGRAM to generate the conftest file
contents. A new macro AC_LANG_DEFINES_PROVIDED exists if you have
a compelling reason why you cannot use AC_LANG_SOURCE but must
avoid the warning.
** The macro m4_define_default is now documented.
** Symlinked config.cache files are supported; configure now tries to
update non-symlinked cache files atomically, so that concurrent configure
runs do not leave behind broken cache files. It is still unspecified
which subset or union of results is cached though.
** Autotest testsuites should not contain long text lines any more, and be
portable even when very many test groups are used.
** AT_CHECK semantics with respect to the Autotest variable $at_status and
shell execution environment of the arguments are documented now.
** AC_FC_LIBRARY_LDFLAGS now tolerates output from newer gfortran.
** Newly obsolete macros
The following macros have been marked obsolete. New programs
should use the corresponding Gnulib modules. Gnulib not only
detects a larger set of portability problems with these functions,
but also provides complete workarounds.
AC_FUNC_ERROR_AT_LINE AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK
AC_FUNC_MKTIME AC_FUNC_STRTOD
* Major changes in Autoconf 2.67 (2010-07-21) [stable]
Released by Eric Blake, based on git versions 2.66.*.
** AC_CONFIG_SUBDIRS with more than one subdirectory at a time works again.
Regression introduced in 2.66.
** AC_CHECK_SIZEOF of a pointer type works again. Regression introduced in
2.66.
** New macro AC_FC_LINE_LENGTH to accept long Fortran source code lines.
** AC_PREPROC_IFELSE now keeps the preprocessed output in the conftest.i
file for inspection by the commands in the ACTION-IF-TRUE argument.
** AC_INIT again allows parentheses and other characters that are literal
in single- or double-quoted strings, and in quoted and unquoted
here-documents, for its PACKAGE and VERSION arguments. Regression
introduced in 2.66.
** autoreconf passes warning flags to new enough versions of aclocal.
** Running an Autotest testsuite in parallel mode no longer triggers a
race condition that could cause the testsuite run to end early,
fixing a sporadic failure in autoconf's own testsuite. Bug present
since introduction of parallel tests in 2.63b.
* Major changes in Autoconf 2.66 (2010-07-02) [stable]
Released by Eric Blake, based on git versions 2.65.*.
** AC_FUNC_MMAP works in C++ mode again. Regression introduced in 2.65.
** Use of m4_divert without a named diversion now issues a syntax warning,
since it is seldom right to change diversions behind autoconf's back.
** The macros AC_TYPE_INT8_T, AC_TYPE_INT16_T, AC_TYPE_INT32_T, and
AC_TYPE_INT64_T work again. Regression introduced in 2.65.
** AC_PROG_INSTALL correctly uses `shtool' again. Regression introduced
in 2.64.
** Autoconf should work on EBCDIC hosts.
** AC_CHECK_DECL and AC_CHECK_DECLS accept optional function argument types
for overloaded C++ functions.
** AS_SET_CATFILE accepts nonliterals in its variable name argument now.
** Autotest testsuites accept an option --recheck to rerun tests that
failed or passed unexpectedly during the last non-debug testsuite run.
** AC_ARG_ENABLE and AC_ARG_WITH now also accept `+' signs in `--enable-*'
and `--with-*' arguments, converting them to underscores for the variable
names.
** In configure scripts, loading CONFIG_SITE no longer searches PATH,
and problems in loading the configuration site files are diagnosed.
** Autotest testsuites may optionally provide colored test results.
** The previously undocumented Autotest macros AT_ARG_OPTION and
AT_ARG_OPTION_ARG have seen bug fixes and are documented now.
AT_ARG_OPTION has been changed in that the negative of a long option
--OPTION is now --no-OPTION rather than --noOPTION.
** The macro AS_LITERAL_IF is slightly more conservative; text
containing shell quotes are no longer treated as literals.
Furthermore, a new macro, AS_LITERAL_WORD_IF, adds an additional
level of checking that no whitespace occurs in literals.
** The macros AS_TR_SH and AS_TR_CPP no longer expand their results.
** The following macros are now documented:
AS_BOX
** New macro AC_FC_FIXEDFORM to accept fixed-form Fortran.
* Major changes in Autoconf 2.65 (2009-11-21) [stable]
Released by Eric Blake, based on git versions 2.64.*.
** Autoconf is now licensed under the General Public License version 3
or later (GPLv3+). As with earlier versions, the license includes
an exception clause so that you may release a configure script
generated by autoconf under the license of your own program.
** New macros to support Objective C++.
AC_PROG_OBJCXX AC_PROG_OBJCXXCPP
** The following undocumented autoconf macros, removed in Autoconf 2.64,
have been reinstated:
AH_CHECK_HEADERS
These macros are present only for backwards compatibility purposes.
** The macro AC_LANG_COMPILER no longer fails on embedded systems that
lack fopen in the C library, such as AVR or RTEMS (regression
introduced in 2.64).
** The AC_FC_FREEFORM macro no longer suffers from a whitespace bug that
made it fail with some Fortran compilers (regression introduced in
2.64).
** The AC_TYPE_UINT64_T and AC_TYPE_INT64_T macros have been fixed to no
longer mistakenly select a 32-bit type on some compilers (bug present
since macros were introduced in 2.59c).
** The AC_FUNC_MMAP macro has been fixed to be portable to systems like
Cygwin (bug present since macro was introduced in 2.0).
** The following documented autotest macros are new:
AT_CHECK_EUNIT
** The following m4sugar macros now quote their expansion:
m4_toupper m4_tolower
** The following m4sugar macros are new:
m4_escape
** The m4sugar macro m4_text_wrap now copes with embedded quoting without
requiring quadrigraphs. For uses like AC_ARG_VAR([a], [[b c]]),
this gives the intuitive behavior of "[b c]" in the output (2.63
gave the output of "[b], [c]", and 2.64 encountered a failure).
** The `$tmp' temporary directory used in config.status is documented for
public use now.
** config.status now provides a --config option to produce the configuration.
** Many cache variables used by Autoconf's macros are now documented.
** Configure scripts work better on DJGPP by avoiding a bug present in
the DJGPP port of bash 2.04 in handling 'return' in a shell
function (regression introduced in 2.64).
* Major changes in Autoconf 2.64 (2009-07-26) [stable]
Released by Eric Blake, based on git versions 2.63b.*.
** Autoconf now requires GNU M4 1.4.6 or later. Earlier versions of M4
have a bug in regular expression handling that interferes with some
of the speedups provided since Autoconf 2.63. GNU M4 1.4.13 or
later is recommended.
** AS_IF and AS_CASE have been taught to avoid syntax errors even when
given arguments that expand to just whitespace.
** The following documented autoconf macros are new:
AC_ERLANG_SUBST_ERTS_VER
** The autoheader tool now understands m4 macro arguments passed to
AC_DEFINE and AC_DEFINE_UNQUOTED.
** Ensure AT_CHECK can support commands that include a # given with
proper m4 quoting. For shell comments, this is a new feature; for
non-shell comments, this fixes a regression introduced in 2.63b.
Additionally, AT_CHECK correctly supplies shell escapes for
metacharacters occurring in m4 macro expansions within the expected
stdout and stderr parameters.
** The macro AT_CHECK now understands the concept of hard failure. If
a test exits with an unexpected status 99, cleanup actions for the
test are inhibited and the test is treated as a failure regardless
of AT_XFAIL_IF. It also understands the new directives
ignore-nolog, stdout-nolog, and stderr-nolog.
** The following documented autotest macros are new:
AT_CHECK_UNQUOTED AT_FAIL_IF AT_SKIP_IF
** The following documented m4sugar macros are new:
m4_argn m4_copy_force m4_default_nblank m4_default_nblank_quoted
m4_ifblank m4_ifnblank m4_rename_force
** The autoconf testsuite now exercises all Erlang macros.
* Major changes in Autoconf 2.63b (2009-03-31) [beta]
Released by Eric Blake, based on git versions 2.63.*.
** The manual is now shipped under the terms of the GNU FDL 1.3.
** AC_REQUIRE now detects the case of an outer macro which first expands
then later indirectly requires the same inner macro. Previously,
this case led to silent out-of-order expansion (bug present since
2.50); it now issues a syntax warning, and duplicates the expansion
of the inner macro to guarantee dependencies have been met. See
the manual for advice on how to refactor macros in order to avoid
the bug in earlier autoconf versions and avoid increased script
size in the current version.
** AC_DEFUN_ONCE has improved semantics. Previously, a macro declared
with AC_DEFUN_ONCE warned on a second invocation; and out-of-order
expansion was still possible. Now, dependencies are guaranteed,
and subsequent invocations are a silent no-op. This makes
AC_DEFUN_ONCE an ideal macro for silencing AC_REQUIRE warnings.
** The following macros are now defined with AC_DEFUN_ONCE. This means
a subtle change in semantics; previously, an AC_DEFUN macro could
expand one of these macros multiple times or surround the macro
inside shell conditional text to bypass the effects of these
macros, but now the macro will expand exactly once, and prior to
the start of any enclosing AC_DEFUN macro:
AC_CANONICAL_BUILD AC_CANONICAL_HOST AC_CANONICAL_TARGET
AC_HEADER_ASSERT AC_PROG_INSTALL AC_PROG_MKDIR_P
AC_USE_SYSTEM_EXTENSIONS
** AC_LANG_ERLANG works once again (regression introduced in 2.61a).
** AC_HEADER_ASSERT is fixed so that './configure --enable-assert' no
longer mistakenly disables assertions.
** AC_INIT now takes an optional fifth parameter that can be used to
set AC_PACKAGE_URL, a URL for the package's home page; the URL is
used in `configure --help' and is also available via AC_DEFINE.
** Autotest testsuites accept an option --jobs[=N] for parallel testing.
This feature is still in testing, and may not work on every
platform, help in improving it would be appreciated.
** Autotest testsuites do not attempt to write startup error messages
to the log file before that is opened (regression introduced in 2.63).
** Configure scripts now use shell functions. This feature leads to
smaller configure files and faster execution.
** Present But Cannot Be Compiled: Autoconf will now proceed with
the compiler's result if a header is present but cannot be compiled.
The warning is still printed, and you should really fix it by
providing a fourth parameter to AC_CHECK_HEADER/AC_CHECK_HEADERS.
** Autoreconf added aclocal to the set of programs affected by the
`autoreconf -I dir' option.
** The following documented m4sugar macros are new:
m4_chomp m4_chomp_all m4_cleardivert m4_curry m4_default_quoted
m4_esyscmd_s m4_map_args m4_map_args_pair m4_map_args_sep
m4_map_args_w m4_set_map m4_set_map_sep m4_stack_foreach
m4_stack_foreach_lifo m4_stack_foreach_sep
m4_stack_foreach_sep_lifo
** The following m4sugar macros are documented now, but in some cases
with slightly different semantics than what the previous
undocumented version had:
m4_copy m4_dumpdefs m4_rename m4_version_prereq
** The m4sugar macro m4_expand has been taught to handle unterminated
comments and shell case statements. As a result, it is used
internally in more places, such as AC_DEFINE and AT_CHECK. Most
uses of AC_DEFINE and AT_CHECK should not behave any differently;
however, it may be necessary to add double-quoting around
unbalanced `(' where single-quoting used to be sufficient.
** The following documented m4sh macros are new:
AS_INIT_GENERATED AS_LINENO_PREPARE AS_ME_PREPARE AS_SET_STATUS
AS_VAR_APPEND AS_VAR_ARITH AS_VAR_COPY
** The following m4sh macros are documented now, but in some cases
with slightly different semantics than what the previous
undocumented version had:
AS_ECHO AS_ECHO_N AS_ESCAPE AS_EXIT AS_LITERAL_IF AS_UNSET
AS_VAR_IF AS_VAR_POPDEF AS_VAR_PUSHDEF AS_VAR_SET AS_VAR_SET_IF
AS_VAR_TEST_SET AS_VERSION_COMPARE
** The m4sh macros AS_IF and AS_CASE can now be used in shell lists.
The responsibility for supplying a trailing newline now belongs to
the call site, but since most users did not add dnl, this generally
results in fewer empty lines in configure.
* Major changes in Autoconf 2.63 (2008-09-09) [stable]
Released by Eric Blake, based on git versions 2.62.*.
** AC_C_BIGENDIAN does not mistakenly report "universal" for some
bigendian hosts, a regression introduced with universal binary
support in 2.62.
** AC_PATH_X now includes /lib64 and /usr/lib64 in its list of default
library directories.
** AC_USE_SYSTEM_EXTENSIONS no longer conflicts with an external
AC_DEFINE([__EXTENSIONS__]). This fixes a regression introduced in
2.62 when using macros such as AC_AIX that were made obsolete in
favor of the more portable AC_USE_SYSTEM_EXTENSIONS.
** AC_CHECK_TARGET_TOOLS is usable in the non-cross-compile case.
** Newly obsolete macros
The following macro has been marked obsolete, since current porting
targets can safely assume C89 semantics that signal handlers return
void. We have no current plans to remove the macro.
AC_TYPE_SIGNAL
** The macros m4_map and m4_map_sep now ignore any list elements
consisting of just empty quotes, and m4_map_sep now expands its
separator. This fixes a regression in 2.62 when these macros were
first documented, for the sake of clients expecting the semantics
that these macros had prior to that time. The new macros m4_mapall
and m4_mapall_sep, along with extra quoting of the separator, can
be used to get the semantics that m4_map_sep had in 2.62.
** Clients of m4_expand, such as AS_HELP_STRING and AT_SETUP, can now
handle properly quoted but otherwise unbalanced parentheses (for
some macros, this fixes a regression in 2.62).
** Two new quadrigraphs have been introduced: @{:@ for (, and @:}@ for ),
allowing the output of unbalanced parentheses in more contexts.
** The following m4sugar macros are new:
m4_cleardivert m4_joinall m4_mapall m4_mapall_sep m4_reverse
m4_set_add m4_set_add_all m4_set_contains m4_set_contents
m4_set_delete m4_set_difference m4_set_dump m4_set_empty
m4_set_foreach m4_set_intersection m4_set_list m4_set_listc
m4_set_remove m4_set_size m4_set_union
** The following m4sugar macros now accept multiple arguments, as is the
case with underlying m4:
m4_defn m4_popdef m4_undefine
** The following m4sugar macros now guarantee linear scaling; they
previously had linear scaling with m4 1.6 but quadratic scaling
when using m4 1.4.x. All macros built on top of these also gain
the scaling improvements.
m4_bmatch m4_bpatsubsts m4_case m4_cond m4_do m4_dquote_elt
m4_foreach m4_join m4_list_cmp m4_map m4_map_sep m4_max
m4_min m4_shiftn
** AT_KEYWORDS once again performs expansion on its argument, such that
AT_KEYWORDS([m4_if([$1], [], [default])]) no longer complains about
the possibly unexpanded m4_if [regression introduced in 2.62].
** Config header templates `#undef UNDEFINED /* comment */' do not lead to
nested comments any more; regression introduced in 2.62.
* Major changes in Autoconf 2.62 (2008-04-05) [stable]
Released by Eric Blake, based on git versions 2.61a.*.
** Many optimizations have been applied to make overall execution faster.
** Autotest now makes use of shell functions.
** config.status now uses awk instead of sed also for config headers.
- As a side effect, AC_DEFINE and AC_DEFINE_UNQUOTED now handle multi-line
values, i.e., backslash-newline combinations are handled correctly.
Further, for config headers, the total size of values is not limited by
the POSIX length limit of text lines any more, only each single line.
** New config variable `top_build_prefix'.
** New Autoconf macros:
AC_AUTOCONF_VERSION AC_OPENMP AC_PATH_PROGS_FEATURE_CHECK
** AC_C_BIGENDIAN now supports universal binaries a la Mac OS X.
** AC_C_RESTRICT now prefers to #define 'restrict' to a variant spelling
like '__restrict' if the variant spelling is available, as this is
more likely to work when mixing C and C++ code.
** AC_CHECK_ALIGNOF's type argument T is now documented better: it must
be a string of tokens such that "T y;" is a valid member declaration
in a struct.
** AC_CHECK_SIZEOF now accepts objects as well as types: the general rule
is that sizeof (X) works, then AC_CHECK_SIZEOF (X) should work.
** AC_CHECK_TYPE and AC_CHECK_TYPES now work on any C type-name; formerly,
they did not work for function types. In C++, they now work on any
type-id that can be the operand of sizeof; this is similar to C,
except it excludes anonymous struct and union types. Formerly,
some (but not all) C++ types involving anonymous struct and union
were accepted, though this was not documented.
** AC_CONFIG_LINKS now prefers to link against files in the build tree
if found, and it works to link against a file of the same name in
the source tree, even if both trees coincide.
** AC_INIT no longer alters $@; regression introduced in 2.60.
** AC_USE_SYSTEM_EXTENSIONS now defines _ALL_SOURCE for Interix platforms.
** AS_HELP_STRING no longer underquotes its first argument; it also handles
the case where the first argument contains single-quoted commas.
For example, "AS_HELP_STRING([-a, [--arg[=foo]]], [bar])" produces:
" -a, --arg[=foo] bar"
Additionally, the macro now takes two additional arguments,
indent-column and wrap-column; these should not normally be needed,
but can be used to fine-tune how the output text is wrapped.
** AC_PROG_INSTALL now requires an install program that can install multiple
files into a target directory.
** The command 'autoconf -' now correctly processes a file from stdin.
** 'autoreconf -m' now honors $MAKE.
** For all of the directory arguments for 'configure', such as '--prefix'
or '--bindir', trailing slashes are stripped. As an example, if
tab completion in the user's shell appends trailing slashes, the
command './configure --prefix=/usr/' will still result in an
expanded libdir value of /usr/lib, not /usr//lib.
** `configure --help=recursive' now works in read-only trees and from
unconfigured build trees.
** If precious variables differ only in whitespace, then the cache consistency
check warns instead of fails, and reuses the old value.
** AT_BANNER is now documented.
** AT_SETUP now handles macro expansions properly when calculating line