[systemd-devel] [PATCH] build: check for build/link flags harder

[David Herrmann]

Use AC_LINK_IFELSE instead of AC_COMPILE_IFELSE to test for flags that
might succeed during compilation but not during linking. An example is gcc
compiled with libssp support but gnu-ld without it. In this case
-fstack-protector works fine during compilation but fails during linking
as several internal helpers are missing.
---
 m4/attributes.m4 | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/m4/attributes.m4 b/m4/attributes.m4
index 7e080da..aa53ef2 100644
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -42,9 +42,9 @@ AC_DEFUN([CC_CHECK_FLAG_APPEND], [
                  AS_TR_SH([cc_cv_$2_$3]),
           [eval "AS_TR_SH([cc_save_$2])='${$2}'"
            eval "AS_TR_SH([$2])='-Werror $3'"
-           AC_COMPILE_IFELSE([AC_LANG_SOURCE([int a = 0; int main(void) { return a; } ])],
-                                    [eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
-                                    [eval "AS_TR_SH([cc_cv_$2_$3])='no'"])
+           AC_LINK_IFELSE([AC_LANG_SOURCE([int a = 0; int main(void) { return a; } ])],
+                          [eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
+                          [eval "AS_TR_SH([cc_cv_$2_$3])='no'"])
            eval "AS_TR_SH([$2])='$cc_save_$2'"])
 
   AS_IF([eval test x$]AS_TR_SH([cc_cv_$2_$3])[ = xyes],
-- 
1.8.4