Build: Detect supported compiler warning flags better.
Clang and nowadays also GCC accept any -Wfoobar option
but then may give a warning that an unknown warning option
was specified. To avoid adding unsupported warning options,
the options are now tested with -Werror.
Thanks to Charles Diza.
diff --git a/configure.ac b/configure.ac
index 2df6797..e41979b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -749,8 +749,9 @@
do
AC_MSG_CHECKING([if $CC accepts $NEW_FLAG])
OLD_CFLAGS="$CFLAGS"
- CFLAGS="$CFLAGS $NEW_FLAG"
- AC_COMPILE_IFELSE([AC_LANG_SOURCE([void foo(void) { }])], [
+ CFLAGS="$CFLAGS $NEW_FLAG -Werror"
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE(
+ [void foo(void); void foo(void) { }])], [
AM_CFLAGS="$AM_CFLAGS $NEW_FLAG"
AC_MSG_RESULT([yes])
], [
