From 7fb2a408d78857de581d32d32990be833702b854 Mon Sep 17 00:00:00 2001
From: Neels Hofmeyr <neels@hofmeyr.de>
Date: Mon, 5 Mar 2018 20:41:40 +0100
Subject: configure: add --enable-werror

Provide a sane means of adding the -Werror compiler flag.

Currently, some of our jenkins.sh add -Werror by passing 'CFLAGS="-Werror"',
but that actually *overwrites* all the other CFLAGS we might want to have set.

Maintain these exceptions from -Werror:
a) deprecation (allow upstream to mark deprecation without breaking builds);
b) "#warning" pragmas (allow to remind ourselves of errors without breaking
   builds)

As a last configure step before generating the output files, print the complete
CFLAGS and CPPFLAGS by means of AC_MSG_RESULT.

Change-Id: I5280a692eaf8f626523e0fd929d1febaa2859104
---
 configure.ac | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/configure.ac b/configure.ac
index 85270bc..8ecbb77 100644
--- a/configure.ac
+++ b/configure.ac
@@ -53,6 +53,27 @@ then
 	CPPFLAGS="$CPPFLAGS -fsanitize=address -fsanitize=undefined"
 fi
 
+AC_ARG_ENABLE(werror,
+	[AS_HELP_STRING(
+		[--enable-werror],
+		[Turn all compiler warnings into errors, with exceptions:
+		 a) deprecation (allow upstream to mark deprecation without breaking builds);
+		 b) "#warning" pragmas (allow to remind ourselves of errors without breaking builds)
+		]
+	)],
+	[werror=$enableval], [werror="no"])
+if test x"$werror" = x"yes"
+then
+	WERROR_FLAGS="-Werror"
+	WERROR_FLAGS+=" -Wno-error=deprecated -Wno-error=deprecated-declarations"
+	WERROR_FLAGS+=" -Wno-error=cpp" # "#warning"
+	CFLAGS="$CFLAGS $WERROR_FLAGS"
+	CPPFLAGS="$CPPFLAGS $WERROR_FLAGS"
+fi
+
+AC_MSG_RESULT([CFLAGS="$CFLAGS"])
+AC_MSG_RESULT([CPPFLAGS="$CPPFLAGS"])
+
 AC_OUTPUT([Makefile
            def_frame/Makefile
            def_list/Makefile
-- 
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