[PATCH] configure: Add an option to enable -Werror.

[Francois Gouget]

--maintainer-mode already enables -Werror but it it incompatible with
out-of-tree builds. Calling configure with CFLAGS=-Werror causes it to
misdetect some functions like llrint() due to redefinition warnings. And
setting CFLAGS when invoking make risks losing compiler options like -g
-O2.
So add a --enable-werror configure option to allow cleanly using
-Werror.

Signed-off-by: Francois Gouget <fgouget at codeweavers.com>
---
 configure.ac | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/configure.ac b/configure.ac
index 7c3c6d2b670..f722ac5d049 100644
--- a/configure.ac
+++ b/configure.ac
@@ -32,6 +32,7 @@ AC_ARG_ENABLE(win16, AS_HELP_STRING([--disable-win16],[do not include Win16 supp
 AC_ARG_ENABLE(win64, AS_HELP_STRING([--enable-win64],[build a Win64 emulator on AMD64 (won't run Win32 binaries)]))
 AC_ARG_ENABLE(tests, AS_HELP_STRING([--disable-tests],[do not build the regression tests]))
 AC_ARG_ENABLE(maintainer-mode, AS_HELP_STRING([--enable-maintainer-mode],[enable maintainer-specific build rules]))
+AC_ARG_ENABLE(werror, AS_HELP_STRING([--enable-werror],[treat compilation warnings as errors]))
 
 AC_ARG_WITH(alsa,      AS_HELP_STRING([--without-alsa],[do not use the Alsa sound support]))
 AC_ARG_WITH(capi,      AS_HELP_STRING([--without-capi],[do not use CAPI (ISDN support)]))
@@ -373,6 +374,9 @@ else
   dnl Maintainer mode requires gettext
   with_gettext=yes
   with_gettextpo=yes
+
+  dnl Maintainer mode wants -Werror
+  enable_werror=yes
 fi
 
 test "x$with_gettext" != xno || MSGFMT=false
@@ -1092,7 +1096,7 @@ then
 
         WINE_TRY_CROSSCFLAGS([-Wl,-delayload,autoconftest.dll], [AC_SUBST(DELAYLOADFLAG,["-Wl,-delayload,"])])
 
-        if test "x$enable_maintainer_mode" = xyes
+        if test "x$enable_werror" = "xyes"
         then
             WINE_TRY_CROSSCFLAGS([-Werror])
         fi
@@ -2080,8 +2084,8 @@ char*f(const char *h,char n) {return strchr(h,n);}]])],[ac_cv_c_logicalop_noisy=
 
   CFLAGS=$saved_CFLAGS
 
-  dnl Enable -Werror for maintainer mode
-  if test "x$enable_maintainer_mode" = "xyes"
+  dnl Enable -Werror
+  if test "x$enable_werror" = "xyes"
   then
       WINE_TRY_CFLAGS([-Werror])
   fi
-- 
2.20.1