dnl well.
dnl Check if FLAG in ENV-VAR is supported by compiler and append it
-dnl to WHERE-TO-APPEND variable
+dnl to WHERE-TO-APPEND variable. Note that we invert -Wno-* checks to
+dnl -W* as gcc cannot test for negated warnings.
dnl CC_CHECK_FLAG_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG])
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 $3'"
+ eval "AS_TR_SH([$2])='-Werror `echo "$3" | sed 's/^-Wno-/-W/'`'"
AC_LINK_IFELSE([AC_LANG_SOURCE([int main(void) { return 0; } ])],
[eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
[eval "AS_TR_SH([cc_cv_$2_$3])='no'"])