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AC_PROG_CC_STDC: fold into AC_PROG_CC, removing C11 macro

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* NEWS:
* doc/autoconf.texi (C Compiler): Document the following.
* lib/autoconf/c.m4 (AC_PROG_CC): Check for the latest C version
supported, not just C89.
(_AC_C_STD_TRY): Keep track of the options we add to bring
the C compiler up to standard, so that we can undo it if the
user later requests some other C standard.
(_AC_PROG_CC_FORCE_VERSION): New macro.
(AC_PROG_CC_C89, AC_PROG_CC_C99): Use it.  These macros now
have a documented side effect of changing the C version requested.
(AC_PROG_CC_C11): Remove.  It wasn't useful.
(AC_PROG_CC_STDC): Now an obsolescent alias for AC_PROG_CC.
(AC_C_PROTOTYPES): Allow any standard C version, not just c89.
Don't chatter, since we don't actually run any checking code.
* lib/autoconf/types.m4 (AC_TYPE_LONG_LONG_INT)
(AC_TYPE_UNSIGNED_LONG_LONG_INT): Treat C11 like C99.
* TODO: Remove the TODO item corresponding to the above.
This commit is contained in:
Paul Eggert 2012-09-20 14:32:06 -07:00
parent 787acdfaa7
commit 8e796471bf
5 changed files with 116 additions and 126 deletions
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9
NEWS
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@ -7,10 +7,13 @@ GNU Autoconf NEWS - User visible changes.
** Macros
- New macro AC_PROG_CC_C11.
- AC_PROG_CC now prefers C11 if available, falling back on C99 and
then on C89 as before. (There is no AC_PROG_CC_C11 macro, as no
need for one has been identified.)
- AC_PROG_CC_STDC now prefers C11 if available, falling back on C99
and then on C89 as before.
- It is now documented that AC_PROG_CC_C89 and AC_PROG_CC_C99
interfere with each other and with AC_PROG_CC. Applications should
normally use AC_PROG_CC.
- 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

12
TODO
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@ -34,14 +34,6 @@ be performed in another file than confdefs.h, say confh.h, which is
used for config.h generation, but not used in configure's own tests.
** AC_PROG_CC
Currently it tries to put the C compiler in ANSI C mode by default.
We should change this spec so that AC_PROG_CC tries to change the
compiler to be the "nicest" mode, i.e. support for the latest standard
features (currently ISO C99) plus support for all vendor extensions,
even if they are slightly incompatible with C99. The basic idea here
is that AC_PROG_CC should disable pedanticisms and should enable
extensions.
Have a way to specify different default flags to try; see this thread
for more information:
<http://lists.gnu.org/archive/html/bug-autoconf/2008-08/msg00009.html>.
@ -143,7 +135,9 @@ We also need to check the srcext which are supported by the compiler.
In fact, this macro is also probably the right place to check for
objext and exeext.
** AC_PROG_CC_STDC
** AC_PROG_CC
How should the desired ISO version be specified? AC_PROG_CC_C89
do not play well with each other, or with AC_PROG_CC.
Should be: AC_PROG_CC_ISO? Or even more specific for the ISO version?
Should include more tests (e.g., AC_C_CONST etc.)? See Peter for very
useful comments on the technology. Should we make this a new

65
doc/autoconf.texi
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@ -7223,13 +7223,14 @@ makes this invalid. That is why Autoconf stopped issuing
@code{#line} directives.
@end table
@anchor{AC_PROG_CC}
@defmac AC_PROG_CC (@ovar{compiler-search-list})
@acindex{PROG_CC}
@evindex CC
@evindex CFLAGS
@ovindex CC
@ovindex CFLAGS
@caindex prog_cc_c89
@caindex prog_cc_stdc
Determine a C compiler to use. If @code{CC} is not already set in the
environment, check for @code{gcc} and @code{cc}, then for other C
compilers. Set output variable @code{CC} to the name of the compiler
@ -7246,16 +7247,14 @@ this:
AC_PROG_CC([gcc cl cc])
@end example
If the C compiler does not handle function prototypes correctly by
default, try to add an option to output variable @code{CC} to make it
so. This macro tries various options that select standard-conformance
modes on various systems.
If the C compiler cannot compile ISO Standard C (currently
C11), try to add an option to output variable @code{CC} to make it work.
If the compiler does not support C11, fall back to supporting
ISO C99; if C99 does not work, fall back to ANSI C89 (ISO C90).
When testing for ISO C versions, use GNU extensions if available.
After calling this macro you can check whether the C compiler has been
set to accept ANSI C89 (ISO C90); if not, the shell
variable
@code{ac_cv_prog_cc_c89} is set to @samp{no}. See also
@code{AC_C_PROTOTYPES} below.
set to accept Standard C; if not, the shell variable
@code{ac_cv_prog_cc_stdc} is set to @samp{no}.
If using the GNU C compiler, set shell variable @code{GCC} to
@samp{yes}. If output variable @code{CFLAGS} was not already set, set
@ -7324,19 +7323,6 @@ features. To check for characteristics not listed here, use
@code{AC_COMPILE_IFELSE} (@pxref{Running the Compiler}) or
@code{AC_RUN_IFELSE} (@pxref{Runtime}).
@defmac AC_PROG_CC_STDC
@acindex{PROG_CC_STDC}
@caindex prog_cc_stdc
If the C compiler cannot compile ISO Standard C (currently
C11), try to add an option to output variable @code{CC} to make it work.
If the compiler does not support C11, fall back to supporting
ISO C99; if C99 does not work, fall back to ANSI C89 (ISO C90).
After calling this macro you can check whether the C compiler has been
set to accept Standard C; if not, the shell variable
@code{ac_cv_prog_cc_stdc} is set to @samp{no}.
@end defmac
@defmac AC_PROG_CC_C89
@acindex{PROG_CC_C89}
@caindex prog_cc_c89
@ -7351,7 +7337,9 @@ After calling this macro you can check whether the C compiler has been
set to accept ANSI C89; if not, the shell variable
@code{ac_cv_prog_cc_c89} is set to @samp{no}.
This macro is called automatically by @code{AC_PROG_CC}.
This macro is rarely needed. It should be used only if your application
requires C89 and will not work in later C versions. Typical applications
should use @code{AC_PROG_CC} instead.
@end defmac
@defmac AC_PROG_CC_C99
@ -7371,23 +7359,13 @@ in @code{for} loops, and variable length arrays.
After calling this macro you can check whether the C compiler has been
set to accept C99; if not, the shell variable
@code{ac_cv_prog_cc_c99} is set to @samp{no}.
@end defmac
@defmac AC_PROG_CC_C11
@acindex{PROG_CC_C11}
@caindex prog_cc_c11
If the C compiler is not in C11 mode by default, try to add an
option to output variable @code{CC} to make it so. This macro tries
various options that select C11 on some system or another, preferring
extended functionality modes over strict conformance modes. Currently it
considers the compiler to be in C11 mode if it handles @code{_Alignas},
@code{_Alignof}, @code{_Noreturn}, @code{_Static_assert}, UTF-8 string
literals, duplicate @code{typedef}s, and anonymous structures and
unions.
This macro is rarely needed. It should be used only if your application
requires C99 and will not work in later C versions. Typical applications
should use @code{AC_PROG_CC} instead.
After calling this macro you can check whether the C compiler has been
set to accept C11; if not, the shell variable
@code{ac_cv_prog_cc_c11} is set to @samp{no}.
There is no @code{AC_PROG_CC_C11} macro, as no need for one has been
identified.
@end defmac
@defmac AC_C_BACKSLASH_A
@ -14389,8 +14367,8 @@ C variables in libraries.
After the category comes the name of the particular feature being
tested. Any further words in the macro name indicate particular aspects
of the feature. For example, @code{AC_PROG_CC_STDC} checks whether the
C compiler supports ISO Standard C.
of the feature. For example, @code{AC_PROG_MAKE_SET} checks whether
@command{make} sets a variable to its own name.
An internal macro should have a name that starts with an underscore;
Autoconf internals should therefore start with @samp{_AC_}.
@ -23678,6 +23656,11 @@ Replaced by @code{AC_TYPE_PID_T} (@pxref{AC_TYPE_PID_T}).
Replaced by @code{AC_PREFIX_PROGRAM} (@pxref{AC_PREFIX_PROGRAM}).
@end defmac
@defmac AC_PROG_CC_STDC
@acindex{PROG_CC_STDC}
Now done by @code{AC_PROG_CC} (@pxref{AC_PROG_CC}).
@end defmac
@defmac AC_PROGRAMS_CHECK
@acindex{PROGRAMS_CHECK}
Replaced by @code{AC_CHECK_PROGS} (@pxref{AC_CHECK_PROGS}).

80
lib/autoconf/c.m4
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@ -478,7 +478,19 @@ else
GCC=
fi
_AC_PROG_CC_G
_AC_PROG_CC_C89
dnl
dnl Set ac_prog_cc_stdc to the supported C version.
dnl Also set the documented variable ac_cv_prog_cc_stdc;
dnl its name was chosen when it was cached, but it is no longer cached.
_AC_PROG_CC_C11([ac_prog_cc_stdc=c11
ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c11],
[_AC_PROG_CC_C99([ac_prog_cc_stdc=c99
ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99],
[_AC_PROG_CC_C89([ac_prog_cc_stdc=c89
ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89],
[ac_prog_cc_stdc=no
ac_cv_prog_cc_stdc=no])])])
dnl
AC_LANG_POP(C)dnl
])# AC_PROG_CC
@ -1166,13 +1178,15 @@ done
rm -f conftest.$ac_ext
CC=$ac_save_CC
])# AC_CACHE_VAL
ac_prog_cc_stdc_options=
case "x$ac_cv_prog_cc_$1" in
x)
AC_MSG_RESULT([none needed]) ;;
xno)
AC_MSG_RESULT([unsupported]) ;;
*)
CC="$CC $ac_cv_prog_cc_$1"
ac_prog_cc_stdc_options=" $ac_cv_prog_cc_$1"
CC=$CC$ac_prog_cc_stdc_options
AC_MSG_RESULT([$ac_cv_prog_cc_$1]) ;;
esac
AS_IF([test "x$ac_cv_prog_cc_$1" != xno], [$5], [$6])
@ -1423,47 +1437,43 @@ dnl with extended modes being tried first.
])# _AC_PROG_CC_C11
# AC_PROG_CC_C89
# --------------
AC_DEFUN([AC_PROG_CC_C89],
# _AC_PROG_CC_FORCE_VERSION(LOWER-VERSION, UPPER-VERSION)
# -------------------------------------------------------
# Require a compiler for a particular version of C, either C89 or C99.
# LOWER-VERSION uses lower-case c, UPPER-VERSION uses upper-case.
AC_DEFUN([_AC_PROG_CC_FORCE_VERSION],
[ AC_REQUIRE([AC_PROG_CC])dnl
_AC_PROG_CC_C89
if test $ac_prog_cc_stdc != $1; then
ac_save_std_CC=$CC
if test -n "$ac_prog_cc_stdc_options"; then
CC=`expr "X$CC" : 'X\(.*\)'"$ac_prog_cc_stdc_options"
``expr "X$CC" : ".*$ac_prog_cc_stdc_options"'\(.*\)'
`
fi
_AC_PROG_CC_$2(
[ac_prog_cc_stdc=$1
ac_cv_prog_cc_stdc=$ac_cv_prog_cc_$1],
[CC=$ac_save_std_CC
AC_MSG_WARN([$2 compiler not available; falling back on $CC])])
fi
])
# AC_PROG_CC_C89
# --------------
AC_DEFUN([AC_PROG_CC_C89], [_AC_PROG_CC_FORCE_VERSION([c89], [C89])])
# AC_PROG_CC_C99
# --------------
AC_DEFUN([AC_PROG_CC_C99],
[ AC_REQUIRE([AC_PROG_CC])dnl
_AC_PROG_CC_C99
])
AC_DEFUN([AC_PROG_CC_C99], [_AC_PROG_CC_FORCE_VERSION([c99], [C99])])
# AC_PROG_CC_C11
# --------------
AC_DEFUN([AC_PROG_CC_C11],
[ AC_REQUIRE([AC_PROG_CC])dnl
_AC_PROG_CC_C11
])
# There is no AC_PROG_CC_C11, as we have not identified a need for it.
# Applications should use AC_PROG_CC instead.
# AC_PROG_CC_STDC
# ---------------
AC_DEFUN([AC_PROG_CC_STDC],
[ AC_REQUIRE([AC_PROG_CC])dnl
AS_CASE([$ac_cv_prog_cc_stdc],
[no], [ac_cv_prog_cc_c11=no; ac_cv_prog_cc_c99=no; ac_cv_prog_cc_c89=no],
[_AC_PROG_CC_C11([ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c11],
[_AC_PROG_CC_C99([ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99],
[_AC_PROG_CC_C89([ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89],
[ac_cv_prog_cc_stdc=no])])])])
AC_MSG_CHECKING([for $CC option to accept ISO Standard C])
AC_CACHE_VAL([ac_cv_prog_cc_stdc], [])
AS_CASE([$ac_cv_prog_cc_stdc],
[no], [AC_MSG_RESULT([unsupported])],
[''], [AC_MSG_RESULT([none needed])],
[AC_MSG_RESULT([$ac_cv_prog_cc_stdc])])
])
# This has been folded into AC_PROG_CC.
AU_ALIAS([AC_PROG_CC_STDC], [AC_PROG_CC])
# AC_C_BACKSLASH_A
@ -1902,15 +1912,11 @@ fi
# options.
AC_DEFUN([AC_C_PROTOTYPES],
[AC_REQUIRE([AC_PROG_CC])dnl
AC_MSG_CHECKING([for function prototypes])
if test "$ac_cv_prog_cc_c89" != no; then
AC_MSG_RESULT([yes])
if test "$ac_prog_cc_stdc" != no; then
AC_DEFINE(PROTOTYPES, 1,
[Define to 1 if the C compiler supports function prototypes.])
AC_DEFINE(__PROTOTYPES, 1,
[Define like PROTOTYPES; this can be used by system headers.])
else
AC_MSG_RESULT([no])
fi
])# AC_C_PROTOTYPES

76
lib/autoconf/types.m4
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@ -505,36 +505,38 @@ AC_DEFUN([AC_TYPE_LONG_LONG_INT],
AC_REQUIRE([AC_TYPE_UNSIGNED_LONG_LONG_INT])
AC_CACHE_CHECK([for long long int], [ac_cv_type_long_long_int],
[ac_cv_type_long_long_int=yes
if test "x${ac_cv_prog_cc_c99-no}" = xno; then
ac_cv_type_long_long_int=$ac_cv_type_unsigned_long_long_int
if test $ac_cv_type_long_long_int = yes; then
dnl Catch a bug in Tandem NonStop Kernel (OSS) cc -O circa 2004.
dnl If cross compiling, assume the bug is not important, since
dnl nobody cross compiles for this platform as far as we know.
AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[@%:@include <limits.h>
@%:@ifndef LLONG_MAX
@%:@ define HALF \
(1LL << (sizeof (long long int) * CHAR_BIT - 2))
@%:@ define LLONG_MAX (HALF - 1 + HALF)
@%:@endif]],
[[long long int n = 1;
int i;
for (i = 0; ; i++)
{
long long int m = n << i;
if (m >> i != n)
return 1;
if (LLONG_MAX / 2 < m)
break;
}
return 0;]])],
[],
[ac_cv_type_long_long_int=no],
[:])
fi
fi])
case $ac_prog_cc_stdc in
no | c89) ;;
*)
ac_cv_type_long_long_int=$ac_cv_type_unsigned_long_long_int
if test $ac_cv_type_long_long_int = yes; then
dnl Catch a bug in Tandem NonStop Kernel (OSS) cc -O circa 2004.
dnl If cross compiling, assume the bug is not important, since
dnl nobody cross compiles for this platform as far as we know.
AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[@%:@include <limits.h>
@%:@ifndef LLONG_MAX
@%:@ define HALF \
(1LL << (sizeof (long long int) * CHAR_BIT - 2))
@%:@ define LLONG_MAX (HALF - 1 + HALF)
@%:@endif]],
[[long long int n = 1;
int i;
for (i = 0; ; i++)
{
long long int m = n << i;
if (m >> i != n)
return 1;
if (LLONG_MAX / 2 < m)
break;
}
return 0;]])],
[],
[ac_cv_type_long_long_int=no],
[:])
fi;;
esac])
if test $ac_cv_type_long_long_int = yes; then
AC_DEFINE([HAVE_LONG_LONG_INT], [1],
[Define to 1 if the system has the type `long long int'.])
@ -549,12 +551,14 @@ AC_DEFUN([AC_TYPE_UNSIGNED_LONG_LONG_INT],
AC_CACHE_CHECK([for unsigned long long int],
[ac_cv_type_unsigned_long_long_int],
[ac_cv_type_unsigned_long_long_int=yes
if test "x${ac_cv_prog_cc_c99-no}" = xno; then
AC_LINK_IFELSE(
[_AC_TYPE_LONG_LONG_SNIPPET],
[],
[ac_cv_type_unsigned_long_long_int=no])
fi])
case $ac_prog_cc_stdc in
no | c89) ;;
*)
AC_LINK_IFELSE(
[_AC_TYPE_LONG_LONG_SNIPPET],
[],
[ac_cv_type_unsigned_long_long_int=no]);;
esac])
if test $ac_cv_type_unsigned_long_long_int = yes; then
AC_DEFINE([HAVE_UNSIGNED_LONG_LONG_INT], [1],
[Define to 1 if the system has the type `unsigned long long int'.])