build-sys: Perform flag tests in context to existing flags

Fix the CC_CHECK_FLAG_APPEND macro to test appended flags in context to
current flag values. Otherwise, it is possible to append flags colliding
with user's *FLAGS or even previously appended flags that will cause
the build to fail.
This commit is contained in:
Michał Górny 2016-02-06 13:47:30 +01:00
parent 784b22eef5
commit 4c79662e25

View File

@ -43,7 +43,7 @@ AC_DEFUN([CC_CHECK_FLAG_APPEND], [
AC_CACHE_CHECK([if $CC supports flag $3 in envvar $2],
AS_TR_SH([cc_cv_$2_$3]),
[eval "AS_TR_SH([cc_save_$2])='${$2}'"
eval "AS_TR_SH([$2])='-Werror `echo "$3" | sed 's/^-Wno-/-W/'`'"
eval "AS_TR_SH([$2])='${cc_save_$2} -Werror `echo "$3" | sed 's/^-Wno-/-W/'`'"
AC_LINK_IFELSE([AC_LANG_SOURCE(ifelse([$4], [],
[int main(void) { return 0; } ],
[$4]))],