From 09a49afeae2542993d4cdc5d7af22abdfce7a3ba Mon Sep 17 00:00:00 2001 From: Michal Privoznik Date: Tue, 30 May 2023 12:31:23 +0200 Subject: [PATCH] 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 Message-Id: <8e02776d18595a1c575c90a189ff65f1785f76ca.1685442612.git.mprivozn@redhat.com> Signed-off-by: Paolo Bonzini --- meson.build | 26 +++++--------------------- 1 file changed, 5 insertions(+), 21 deletions(-) diff --git a/meson.build b/meson.build index a61d3e9b06..969a84f2a4 100644 --- a/meson.build +++ b/meson.build @@ -1797,8 +1797,7 @@ malloc = [] if get_option('malloc') == 'system' has_malloc_trim = \ get_option('malloc_trim').allowed() and \ - cc.links('''#include - int main(void) { malloc_trim(0); return 0; }''') + cc.has_function('malloc_trim', prefix: '#include ') else has_malloc_trim = false malloc = cc.find_library(get_option('malloc'), required: true) @@ -1811,34 +1810,19 @@ if not has_malloc_trim and get_option('malloc_trim').enabled() endif endif -# Check whether the glibc provides statx() - gnu_source_prefix = ''' #ifndef _GNU_SOURCE #define _GNU_SOURCE #endif ''' -statx_test = gnu_source_prefix + ''' - #include - 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 - 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',