135 lines
4.9 KiB
Plaintext
135 lines
4.9 KiB
Plaintext
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# ===========================================================================
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# https://www.gnu.org/software/autoconf-archive/ax_c___attribute__.html
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#
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# Downloaded into the Network UPS Tools (NUT) codebase from
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# http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_c___attribute__.m4
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# as of 2020-11-20 and adapted for attribute supports we needed
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# ===========================================================================
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#
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# SYNOPSIS
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#
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# AX_C___ATTRIBUTE__
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#
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# DESCRIPTION
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#
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# Provides a test for the compiler support of __attribute__ extensions.
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# Defines HAVE___ATTRIBUTE__ if it is found.
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# Also in particular defines
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# HAVE___ATTRIBUTE__UNUSED_ARG
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# HAVE___ATTRIBUTE__UNUSED_FUNC
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# HAVE___ATTRIBUTE__NORETURN
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# if support for respective values and use-cases of interest for NUT
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# codebase is found.
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#
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# LICENSE
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#
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# Copyright (c) 2008 Stepan Kasal <skasal@redhat.com>
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# Copyright (c) 2008 Christian Haggstrom
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# Copyright (c) 2008 Ryan McCabe <ryan@numb.org>
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# Copyright (c) 2020 Jim Klimov <jimklimov+nut@gmail.com>
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#
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# This program is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the
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# Free Software Foundation; either version 2 of the License, or (at your
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# option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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# Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program. If not, see <https://www.gnu.org/licenses/>.
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#
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# As a special exception, the respective Autoconf Macro's copyright owner
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# gives unlimited permission to copy, distribute and modify the configure
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# scripts that are the output of Autoconf when processing the Macro. You
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# need not follow the terms of the GNU General Public License when using
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# or distributing such scripts, even though portions of the text of the
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# Macro appear in them. The GNU General Public License (GPL) does govern
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# all other use of the material that constitutes the Autoconf Macro.
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#
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# This special exception to the GPL applies to versions of the Autoconf
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# Macro released by the Autoconf Archive. When you make and distribute a
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# modified version of the Autoconf Macro, you may extend this special
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# exception to the GPL to apply to your modified version as well.
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#serial 9
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AC_DEFUN([AX_C___ATTRIBUTE__], [
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AC_LANG_PUSH([C])
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AC_CACHE_CHECK([for __attribute__((unused)) for function arguments], [ax_cv___attribute__unused_arg],
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[AC_COMPILE_IFELSE(
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[AC_LANG_PROGRAM(
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[[#include <stdlib.h>
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static void foo( int);
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static void
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foo(__attribute__ ((unused)) int i) {
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return;
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}
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]], [func(1);])],
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[ax_cv___attribute__unused_arg=yes],
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[ax_cv___attribute__unused_arg=no]
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)
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])
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AC_CACHE_CHECK([for __attribute__((unused)) for functions], [ax_cv___attribute__unused_func],
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[AC_COMPILE_IFELSE(
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[AC_LANG_PROGRAM(
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[[#include <stdlib.h>
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static void foo(void) __attribute__ ((unused));
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static void
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foo(void) {
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return;
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}
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]], [])],
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[ax_cv___attribute__unused_func=yes],
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[ax_cv___attribute__unused_func=no]
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)
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])
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AC_CACHE_CHECK([for __attribute__((noreturn))], [ax_cv___attribute__noreturn],
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[AC_COMPILE_IFELSE(
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[AC_LANG_PROGRAM(
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[[#include <stdlib.h>
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static void foo(void) __attribute__ ((noreturn));
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static void
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foo(void) {
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exit(1);
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}
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]], [foo();])],
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[ax_cv___attribute__noreturn=yes],
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[ax_cv___attribute__noreturn=no]
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)
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])
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AC_LANG_POP([C])
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AC_CACHE_CHECK([for at least some __attribute__ support], [ax_cv___attribute__],
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[if test "$ax_cv___attribute__unused_arg" = "yes" \
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|| test "$ax_cv___attribute__unused_func" = "yes" \
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|| test "$ax_cv___attribute__noreturn" = "yes" \
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; then
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dnl # Some values did not error, support for keyword itself exists
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ax_cv___attribute__=yes
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else
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dnl # At least none of the options we are interested in work...
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ax_cv___attribute__=no
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fi
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])
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if test "$ax_cv___attribute__unused_arg" = "yes"; then
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AC_DEFINE([HAVE___ATTRIBUTE__UNUSED_ARG], 1, [define if your compiler has __attribute__((unused)) for function arguments])
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fi
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if test "$ax_cv___attribute__unused_func" = "yes"; then
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AC_DEFINE([HAVE___ATTRIBUTE__UNUSED_FUNC], 1, [define if your compiler has __attribute__((unused)) for functions])
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fi
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if test "$ax_cv___attribute__noreturn" = "yes"; then
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AC_DEFINE([HAVE___ATTRIBUTE__NORETURN], 1, [define if your compiler has __attribute__((noreturn))])
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fi
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if test "$ax_cv___attribute__" = "yes"; then
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AC_DEFINE([HAVE___ATTRIBUTE__], 1, [define if your compiler has __attribute__])
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fi
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])
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