meson: Avoid implicit declaration of absent functions
While detecting a presence of a function via 'cc.links()'
gives desired result (i.e. detects whether function is present),
it also produces a warning on systems where the function is not
present (into meson-log.txt), e.g.:
qemu.git/build/meson-private/tmph74x3p38/testfile.c:2:34: \
warning: implicit declaration of function 'malloc_trim' [-Wimplicit-function-declaration]
And some distributions (e.g. Gentoo) parse the meson log and
consider these erroneous because it can lead to feature
misdetection (see [1]).
We can check whether given function exists via
'cc.has_function()' or whether STATX_* macros exist via
'cc.has_header_symbol()'.
1: https://wiki.gentoo.org/wiki/Modern_C_porting
Resolves: https://bugs.gentoo.org/898810
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <8e02776d18595a1c575c90a189ff65f1785f76ca.1685442612.git.mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/meson.build b/meson.build
index a61d3e9..969a84f 100644
--- a/meson.build
+++ b/meson.build
@@ -1797,8 +1797,7 @@
if get_option('malloc') == 'system'
has_malloc_trim = \
get_option('malloc_trim').allowed() and \
- cc.links('''#include <malloc.h>
- int main(void) { malloc_trim(0); return 0; }''')
+ cc.has_function('malloc_trim', prefix: '#include <malloc.h>')
else
has_malloc_trim = false
malloc = cc.find_library(get_option('malloc'), required: true)
@@ -1811,34 +1810,19 @@
endif
endif
-# Check whether the glibc provides statx()
-
gnu_source_prefix = '''
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
'''
-statx_test = gnu_source_prefix + '''
- #include <sys/stat.h>
- int main(void) {
- struct statx statxbuf;
- statx(0, "", 0, STATX_BASIC_STATS, &statxbuf);
- return 0;
- }'''
-has_statx = cc.links(statx_test)
+# Check whether the glibc provides STATX_BASIC_STATS
+
+has_statx = cc.has_header_symbol('sys/stat.h', 'STATX_BASIC_STATS', prefix: gnu_source_prefix)
# Check whether statx() provides mount ID information
-statx_mnt_id_test = gnu_source_prefix + '''
- #include <sys/stat.h>
- int main(void) {
- struct statx statxbuf;
- statx(0, "", 0, STATX_BASIC_STATS | STATX_MNT_ID, &statxbuf);
- return statxbuf.stx_mnt_id;
- }'''
-
-has_statx_mnt_id = cc.links(statx_mnt_id_test)
+has_statx_mnt_id = cc.has_header_symbol('sys/stat.h', 'STATX_MNT_ID', prefix: gnu_source_prefix)
have_vhost_user_blk_server = get_option('vhost_user_blk_server') \
.require(targetos == 'linux',
