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, 4 insertions, 2 deletions

diff --git a/lib-src/Makefile.in b/lib-src/Makefile.in
index cc1757e4e3b..6732030a648 100644
--- a/lib-src/Makefile.in
+++ b/lib-src/Makefile.in
@@ -36,8 +36,9 @@ configuration=@configuration@
 EXEEXT=@EXEEXT@
 C_SWITCH_SYSTEM=@C_SWITCH_SYSTEM@
 C_SWITCH_MACHINE=@C_SWITCH_MACHINE@
-C_WARNINGS_SWITCH = @C_WARNINGS_SWITCH@
 PROFILING_CFLAGS = @PROFILING_CFLAGS@
+WARN_CFLAGS = @WARN_CFLAGS@
+WERROR_CFLAGS = @WERROR_CFLAGS@
 
 # Program name transformation.
 TRANSFORM = @program_transform_name@
@@ -167,7 +168,8 @@ LIBS_SYSTEM = @LIBS_SYSTEM@
 # Those files shared with other GNU utilities need HAVE_CONFIG_H
 # defined before they know they can take advantage of the information
 # in ../src/config.h.
-BASE_CFLAGS = $(C_SWITCH_SYSTEM) $(C_SWITCH_MACHINE) ${C_WARNINGS_SWITCH} \
+BASE_CFLAGS = $(C_SWITCH_SYSTEM) $(C_SWITCH_MACHINE) \
+              $(WARN_CFLAGS) $(WERROR_CFLAGS) \
               -DHAVE_CONFIG_H -I. -I../src -I../lib \
               -I${srcdir} -I${srcdir}/../src -I${srcdir}/../lib