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(AC_LANG_FUNC_LINK_TRY(C)): Use the function f

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nontrivially in main's body, so that f's external declaration is
not optimized away in AIX.  This should fix the bug reported by
Martin Frydl in
<http://mail.gnu.org/pipermail/autoconf/2002-November/014508.html>.
This commit is contained in:
Paul Eggert 2002-12-03 07:00:37 +00:00
parent 1ebbbb55ff
commit 2c9f4bf3aa
1 changed files with 23 additions and 7 deletions
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30
lib/autoconf/c.m4
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@ -166,15 +166,25 @@ char $2 ();])], [$2 ();])])
# <sys/types.h> which includes <sys/select.h> which contains a
# prototype for select. Similarly for bzero.
#
# This test used to assign f=$1 in main(), but that was optimized away by HP
# unbundled cc A.05.36 for ia64 under +O3, presumably on the basis that
# there's no need to do that store if the program is about to exit.
# This test used to merely assign f=$1 in main(), but that was
# optimized away by HP unbundled cc A.05.36 for ia64 under +O3,
# presumably on the basis that there's no need to do that store if the
# program is about to exit. Conversely, the AIX linker optimizes an
# unused external declaration that initializes f=$1. So this test
# program has both an external initialization of f, and a use of f in
# main that affects the exit status.
#
m4_define([AC_LANG_FUNC_LINK_TRY(C)],
[AC_LANG_PROGRAM(
[/* System header to define __stub macros and hopefully few prototypes,
which can conflict with char $1 (); below. */
#include <assert.h>
which can conflict with char $1 (); below.
Prefer <limits.h> to <assert.h> if __STDC__ is defined, since
<limits.h> exists even on freestanding compilers. */
#ifdef __STDC__
# include <limits.h>
#else
# include <assert.h>
#endif
/* Override any gcc2 internal prototype to avoid an error. */
#ifdef __cplusplus
extern "C"
@ -194,7 +204,7 @@ char (*f) () = $1;
#ifdef __cplusplus
}
#endif
])])
], [return f != $1;])])
# AC_LANG_BOOL_COMPILE_TRY(C)(PROLOGUE, EXPRESSION)
@ -323,9 +333,15 @@ for ac_[]_AC_LANG_ABBREV[]_preproc_warn_flag in '' yes
do
# Use a header file that comes with gcc, so configuring glibc
# with a fresh cross-compiler works.
# Prefer <limits.h> to <assert.h> if __STDC__ is defined, since
# <limits.h> exists even on freestanding compilers.
# On the NeXT, cc -E runs the code through the compiler's parser,
# not just through cpp. "Syntax error" is here to catch this case.
_AC_PREPROC_IFELSE([AC_LANG_SOURCE([[@%:@include <assert.h>
_AC_PREPROC_IFELSE([AC_LANG_SOURCE([[@%:@ifdef __STDC__
@%:@ include <limits.h>
@%:@else
@%:@ include <assert.h>
@%:@endif
Syntax error]])],
[],
[# Broken: fails on valid input.