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.

1 files changed, 15 insertions, 2 deletions

diff --git a/src/regex.c b/src/regex.c
index 0f9150193e..d16a514805 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -33,6 +33,19 @@
   #pragma alloca
 #endif
 
+/* Ignore some GCC warnings for now.  This section should go away
+   once the Emacs and Gnulib regex code is merged.  */
+#if (__GNUC__ == 4 && 3 <= __GNUC_MINOR__) || 4 < __GNUC__
+# pragma GCC diagnostic ignored "-Wstrict-overflow"
+# ifndef emacs
+#  pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+#  pragma GCC diagnostic ignored "-Wunused-function"
+#  pragma GCC diagnostic ignored "-Wunused-macros"
+#  pragma GCC diagnostic ignored "-Wunused-result"
+#  pragma GCC diagnostic ignored "-Wunused-variable"
+# endif
+#endif
+
 #ifdef HAVE_CONFIG_H
 # include <config.h>
 #endif
@@ -198,7 +211,7 @@
 
 /* When used in Emacs's lib-src, we need xmalloc and xrealloc. */
 
-void *
+static void *
 xmalloc (size_t size)
 {
   register void *val;
@@ -211,7 +224,7 @@ xmalloc (size_t size)
   return val;
 }
 
-void *
+static void *
 xrealloc (void *block, size_t size)
 {
   register void *val;