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])='$3'"
+ 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'"])