[devel] autoconf-2.69b released [beta]

[Zack Weinberg]

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We are pleased to announce beta release 2.69b of GNU Autoconf.

This release includes eight years of development work since the
previous release, 2.69.  See below for the detailed list of changes
since the previous version, as summarized by the NEWS file.

Because it has been such a long time, and because some of the changes
potentially break existing Autoconf scripts, we are conducting a
public beta test before the final release of version 2.70.  Please
test this beta with your autoconf scripts, and report any problems you
find to the Savannah bug tracker:

   https://savannah.gnu.org/support/?func=additem&group=autoconf

Please also send general comments and feedback to <autoconf на gnu.org>.

Please also spread this announcement widely, so that as many Autoconf
users as possible hear about it.

The final release of Autoconf 2.70 is tentatively scheduled for three
months from now.  We may make more beta releases during this period.


Here are the compressed sources:
  https://alpha.gnu.org/gnu/autoconf/autoconf-2.69b.tar.gz   (1.9MB)
  https://alpha.gnu.org/gnu/autoconf/autoconf-2.69b.tar.xz   (1.3MB)

Here are the GPG detached signatures[*]:
  https://alpha.gnu.org/gnu/autoconf/autoconf-2.69b.tar.gz.sig
  https://alpha.gnu.org/gnu/autoconf/autoconf-2.69b.tar.xz.sig

Use a mirror for higher download bandwidth:
  https://www.gnu.org/order/ftp.html

[*] Use a .sig file to verify that the corresponding file (without the
.sig suffix) is intact.  First, be sure to download both the .sig file
and the corresponding tarball.  Then, run a command like this:

  gpg --verify autoconf-2.69b.tar.gz.sig

If that command fails because you don't have the required public key,
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  gpg --keyserver keys.gnupg.net --recv-keys ED97E90E62AA7E34

and rerun the 'gpg --verify' command.

This release was bootstrapped with the following tools:
  Automake 1.15.1

NEWS

* Noteworthy changes in release 2.69b (2020-07-13) [beta]

** config.log properly escapes arguments in the header comment;
   config.status --config output is now quoted in a more readable fashion

** Configure scripts now support a '--runstatedir' option, which
   defaults to '${localstatedir}/run', and which can be used to place
   per-process temporary runtime files (such as pid files) into '/run'
   instead of '/var/run'.

** The use of the long-deprecated name 'configure.in' for the autoconf
   input file now elicits a warning in the 'obsolete' category.

** Older version of automake and aclocal (< 1.8) are no longer supported
   by autoreconf.

** Use of printf is now recommended instead of working around bugs in
   echo.  The macros AS_ECHO and AS_ECHO_N now expand unconditionally to
   'printf "%s\n"' and 'printf %s'.

** 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.

** When checking for missing templates, autoheader now takes any
   templates defined in the inputs of secondary config headers into
   account.  This makes it possible to use AC_DEFINE for secondary
   headers without duplicating the template in the main config header.

** Many macros have been improved to expand their arguments
   once and only once.  This makes Б─≤autoconfБ─≥ run faster.  However, it
   may break configure scripts that did not quote all macro arguments
   properly.  The Б─≤M4 QuotationБ─≥ section of the manual explains how to
   quote macro arguments properly.

** Several macros that are commonly used early in a configure
   script, such as AC_PROG_CC, have been optimized and no longer
   invoke as many subroutine macros as they used to.  This can expose
   several classes of 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 internally, are not safe to
     use inside of hand-written shell conditional or looping
     constructs.  Use AS_IF, AS_CASE, AS_FOR, etc. instead.
     (See the Б─°Prerequisite MacrosБ─² section of the manual for
     further explanation.)

     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.

** 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.

** 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.

** Macros

- - New macro AC_C__GENERIC.

- - AC_C_VARARRAYS now defines __STDC_NO_VLA__ if variable-length
  arrays are not supported and if the compiler does not already
  define __STDC_NO_VLA__.  This is for compatibility with C11.
  For backward compatibility with Autoconf 2.61-2.69 AC_C_VARARRAYS
  still defines HAVE_C_VARARRAYS, but this usage is obsolescent.

- - AC_CONFIG_MACRO_DIRS
  New macro, used to declare multiple directories when looking for
  local M4 macros.  This macro overcomes some of the shortfalls in the
  older AC_CONFIG_MACRO_DIR, which could only be used once; although
  the older macro remains for compatibility with older tools.  The
  newer macro will be used by the upcoming Automake 1.13 release to
  eliminate the need to specify ACLOCAL_AMFLAGS in Makefile.am.

- - AC_PROG_CC now prefers C11 if available, falling back on C99 and
  then on C89 as before.  Similarly, AC_PROG_CXX now prefers C++11
  if available, falling back on C++98.

- - AC_PROG_CC is now defined via AC_DEFUN_ONCE, to avoid bloat in 'configure'.

- - AC_PROG_CC_STDC, AC_PROG_CC_C89, AC_PROG_CC_C99 have been marked as obsolete.
  Applications should use AC_PROG_CC.

- - AC_PROG_YACC now uses 'bison -o y.tab.c' instead of 'bison -y', so that
  by default it no longer warns about Bison extensions.  Add -Wyacc to
  YFLAGS to enable these warnings.

- - AC_USE_SYSTEM_EXTENSIONS now enables more extensions on HP-UX,
  macOS, and MINIX, as well as on systems conforming to recent
  ISO/IEC C technical reports and specifications.

- - AC_CHECK_DECL and AC_CHECK_DECLS can now report missing declarations for
  functions that are also Clang compiler builtins.

- - AC_FUNC_VFORK now checks for the signal-handling bug in Solaris 2.4 'vfork'.
  Formerly, it ignored this bug, so that Emacs could use some tricky
  code on that platform.  Solaris 2.4 has not been supported since
  2003 and nowadays it's better to omit that old trick.

- - 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

- - AC_CHECK_HEADER and AC_CHECK_HEADERS now default to doing only 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 has been streamlined.  It now assumes that the
  ISO C90 headers 'stdlib.h' and 'string.h' are unconditionally
  available, and does not include the pre-standard header 'memory.h'
  at all.  If the POSIX header 'strings.h' exists, it will be
  included; it is assumed to be safe to include both 'string.h' and
  'strings.h' in the same source file.  We are not aware of any
  current system that violates any of the above assumptions.

  For compatibility's sake, the C preprocessor macros STDC_HEADERS,
  HAVE_STDLIB_H, and HAVE_STRING_H are defined unconditionally.
  These preprocessor macros should be considered obsolescent.

  Future releases of Autoconf may reduce the set of headers checked
  for by AC_INCLUDES_DEFAULT.

- - AC_HEADER_STDC and AC_HEADER_TIME are now stubs which will be
  removed from 'configure.ac' by 'autoupdate'.  For compatibility's
  sake, the stubs (and their 'autoupdate' replacements) continue to
  define the C preprocessor macros STDC_HEADERS and TIME_WITH_SYS_TIME,
  respectively, but without actually checking for the ancient systems
  where formerly those macros would not be defined.

  These macros were already labeled obsolescent in the manual.

- - New macro, AC_CHECK_INCLUDES_DEFAULT.  It causes the checks normally
  performed as a side-effect by AC_INCLUDES_DEFAULT to happen at that
  point in 'configure', 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.

- - The AC_CHECK_FUNCS_ONCE and AC_CHECK_HEADERS_ONCE macros now support
  use with multiple languages, rather than forcing all checks in the
  language used by the first encounter of the macro.

- - AS_INIT now writes only the base filename of the primary input file
  into the generated script.  This avoids embedding (part of) the path
  to the source directory in generated files, which hinders build
  reproducibility.

  We believe this was the only case where generated file contents could
  change depending on the build environment.  If you find any other cases
  please report them as bugs.

- - The obsolete and undocumented macro AC_CONFIG_HEADER is now
  diagnosed as obsolete, and replaced with AC_CONFIG_HEADERS by
  autoupdate.

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