configure: new option --enable-gcc-warnings

I have been using this change for many months in my private copy
of Emacs, and have used it to find several bugs.  It's mature
enough to publish now.
* Makefile.in (GNULIB_MODULES): Add warnings, manywarnings.
* configure.in: Support --enable-gcc-warnings, in the style of
other GNU packages such as coreutils.
(C_WARNINGS_SWITCH): Remove, replacing with...
(WARN_CFLAGS, GNULIB_WARN_CFLAGS): New variable.
(PKG_CHECK_MODULES, C_SWITCH_X_SITE): Use -isystem rather than -I,
when including system files with GCC.
* etc/NEWS: Mention --enable-gcc-warnings.
* lib/Makefile.am (AM_CFLAGS): New macro.
* m4/manywarnings.m4, m4/warnings.m4: New files, from gnulib.
* lib-src/Makefile.in (C_WARNINGS_SWITCH): Remove.
(WARN_CFLAGS, WERROR_CFLAGS): New macros.
(BASE_CFLAGS): Use new macros rather than old.
* lwlib/Makefile.in (C_WARNINGS_SWITCH): Remove.
(WARN_CFLAGS, WERROR_CFLAGS): New macros.
(ALL_CFLAGS): Use new macros rather than old.
* oldXMenu/Makefile.in (C_WARNINGS_SWITCH): Remove.
(WARN_CFLAGS, WERROR_CFLAGS): New macros.
(ALL_CFLAGS): Use new macros rather than old.
* src/Makefile.in (C_WARNINGS_SWITCH): Remove.
(WARN_CFLAGS, WERROR_CFLAGS): New macros.
(ALL_CFLAGS): Use new macros rather than old.
* src/process.c: Ignore -Wstrict-overflow to work around GCC bug 52904.
* src/regex.c: Ignore -Wstrict-overflow.  If !emacs, also ignore
-Wunused-but-set-variable, -Wunused-function, -Wunused-macros,
-Wunused-result, -Wunused-variable.  This should go away once
the Emacs and Gnulib regex code is merged.
(xmalloc, xrealloc): Now static.

2 files changed, 11 insertions, 2 deletions

diff --git a/lwlib/ChangeLog b/lwlib/ChangeLog
index a4bb243f35d..f4800bc4bb0 100644
--- a/lwlib/ChangeLog
+++ b/lwlib/ChangeLog
@@ -1,3 +1,10 @@
+2012-04-09  Paul Eggert  <eggert@cs.ucla.edu>
+
+        configure: new option --enable-gcc-warnings
+        * Makefile.in (C_WARNINGS_SWITCH): Remove.
+        (WARN_CFLAGS, WERROR_CFLAGS): New macros.
+        (ALL_CFLAGS): Use new macros rather than old.
+
 2011-10-13  Dmitry Antipov  <dmantipov@yandex.ru>
 
         * lwlib-Xaw.c (openFont, xaw_destroy_instance): Replace free with
diff --git a/lwlib/Makefile.in b/lwlib/Makefile.in
index db108862d70..76507ac4b24 100644
--- a/lwlib/Makefile.in
+++ b/lwlib/Makefile.in
@@ -29,8 +29,9 @@ C_SWITCH_X_SITE=@C_SWITCH_X_SITE@
 C_SWITCH_X_SYSTEM=@C_SWITCH_X_SYSTEM@
 C_SWITCH_SYSTEM=@C_SWITCH_SYSTEM@
 C_SWITCH_MACHINE=@C_SWITCH_MACHINE@
-C_WARNINGS_SWITCH = @C_WARNINGS_SWITCH@
 PROFILING_CFLAGS = @PROFILING_CFLAGS@
+WARN_CFLAGS = `echo @WARN_CFLAGS@ | sed 's/ -Wwrite-strings//'`
+WERROR_CFLAGS = @WERROR_CFLAGS@
 
 CC=@CC@
 CFLAGS=@CFLAGS@
@@ -54,7 +55,8 @@ OBJS = lwlib.o $(TOOLKIT_OBJS) lwlib-utils.o
 ## There are no generated lwlib files, hence no need for -I.
 ALL_CFLAGS= $(C_SWITCH_SYSTEM) $(C_SWITCH_X_SITE) \
   $(C_SWITCH_X_SYSTEM) $(C_SWITCH_MACHINE) \
-  $(C_WARNINGS_SWITCH) $(PROFILING_CFLAGS) $(CFLAGS) \
+  $(WARN_CFLAGS) $(WERROR_CFLAGS) \
+  $(PROFILING_CFLAGS) $(CFLAGS) \
   -DHAVE_CONFIG_H -Demacs -I../src \
   -I$(srcdir) -I$(srcdir)/../src -I../lib -I$(srcdir)/../lib