[Mesa-dev] [PATCH] m4: add Werror when checking for compiler flags

Emil Velikov emil.l.velikov at gmail.com
Wed Oct 24 17:57:00 UTC 2018

Seemingly that at some point clang started accepting _any_ flags,
whereas previously it would error out.

These days, you can give it -Whamsandwich and it will succeed, while
at the same time throwing an annoying warning.

Add -Werror so that everything gets flagged and set accordingly.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108082
Cc: Eric Engestrom <eric.engestrom at intel.com>
Cc: Dylan Baker <dylan at pnwbakers.com>
Cc: Vinson Lee <vlee at freedesktop.org>
Repored-by: Vinson Lee <vlee at freedesktop.org>
Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
 m4/ax_check_compile_flag.m4 | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
index 51df0c09a7a..0fdca907e8b 100644
--- a/m4/ax_check_compile_flag.m4
+++ b/m4/ax_check_compile_flag.m4
@@ -55,6 +55,11 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
+# Emil:
+# Toggle Werror since at some point clang started treating unknown -W
+# flags as warnings, succeeding with the build, yet issuing an annoying
+# warning.
 #serial 3
@@ -62,7 +67,7 @@ AC_DEFUN([AX_CHECK_COMPILE_FLAG],
 AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [

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