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wmaker/m4/wm_prog_cc_c11.m4
Christophe CURIS 78690de103 configure: cosmetic improvements on comments
This patch brings more consistency in the presentation of comments,
including:
 - 2 line spaces between blocks (M4 macro tend to make the file look quite
bulky, so it is making the file more aerated)
 - fixes in the length of underlining
 - adding a few comments on the reason of the check to ease maintainance

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>
2015-01-02 10:08:09 +00:00

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# wm_prog_cc_c11.m4 - Macros to see if compiler may support STD C11
#
# Copyright (c) 2013 Christophe CURIS
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
# WM_PROG_CC_C11
# --------------
#
# Check if the compiler supports C11 standard natively, or if any
# option may help enabling the support
# This is (in concept) similar to AC_PROG_CC_C11, which is unfortunately
# not yet available in autotools; as a side effect we only check for
# compiler's acknowledgement and a few features instead of full support
AC_DEFUN_ONCE([WM_PROG_CC_C11],
[AC_CACHE_CHECK([for C11 standard support], [wm_cv_prog_cc_c11],
[wm_cv_prog_cc_c11=no
wm_save_CFLAGS="$CFLAGS"
for wm_arg in dnl
"% native" dnl
"-std=c11"
do
CFLAGS="$wm_save_CFLAGS `echo $wm_arg | sed -e 's,%.*,,' `"
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([], [dnl
#if __STDC_VERSION__ < 201112L
fail_because_stdc_version_is_older_than_C11;
#endif
])],
[wm_cv_prog_cc_c11="`echo $wm_arg | sed -e 's,.*% *,,' `" ; break])
done
CFLAGS="$wm_save_CFLAGS"])
AS_CASE([$wm_cv_prog_cc_c11],
[no|native], [],
[CFLAGS="$CFLAGS $wm_cv_prog_cc_c11"])
])
# WM_PROG_CC_NESTEDFUNC
# ---------------------
#
# Check if the compiler support declaring Nested Functions (that means
# declaring a function inside another function).
#
# If the compiler does not support them, then the Automake conditional
# USE_NESTED_FUNC will be set to false, in which case the Makefile will
# use the script 'scripts/nested-func-to-macro.sh' to generate a modified
# source with the nested function transformed into a Preprocessor Macro.
AC_DEFUN_ONCE([WM_PROG_CC_NESTEDFUNC],
[AC_CACHE_CHECK([if compiler supports nested functions], [wm_cv_prog_cc_nestedfunc],
[AC_COMPILE_IFELSE(
[AC_LANG_SOURCE([[
int main(int narg, char **argv)
{
int local_variable;
int nested_function(int argument)
{
/* Checking we have access to upper level's scope, otherwise it is of no use */
return local_variable + argument;
}
/* To avoid a warning for unused parameter, that may falsely fail */
(void) argv;
/* Initialise using the parameter to main so the compiler won't be tempted to optimise too much */
local_variable = narg + 1;
return nested_function(2);
}]]) ],
[wm_cv_prog_cc_nestedfunc=yes],
[wm_cv_prog_cc_nestedfunc=no]) ])
AM_CONDITIONAL([USE_NESTED_FUNC], [test "x$wm_cv_prog_cc_nestedfunc" != "xno"])dnl
])