+# error "your version of gcc is older than $1.$2"
+#endif
+ ]]),
+ ], [$3], [$4])
+ ]
+)
+
+AC_ARG_ENABLE([gcc-warnings],
+ [AS_HELP_STRING([--enable-gcc-warnings],
+ [turn on many GCC warnings (for developers; best with GNU make)])],
+ [case $enableval in
+ yes|no) ;;
+ *) AC_MSG_ERROR([bad value $enableval for gcc-warnings option]) ;;
+ esac
+ gl_gcc_warnings=$enableval],
+ [gl_gcc_warnings=no
+ if test -d "$srcdir"/.git; then
+ gl_GCC_VERSION_IFELSE([4], [6], [gl_gcc_warnings=yes])
+ fi]
+)
+
+if test "$gl_gcc_warnings" = yes; then
+ gl_WARN_ADD([-Werror], [WERROR_CFLAGS])
+ AC_SUBST([WERROR_CFLAGS])
+
+ nw=
+ # This, $nw, is the list of warnings we disable.
+ nw="$nw -Wformat-nonliteral" # warnings in Fedora 17 stdio.h
+ nw="$nw -Wvla" # warnings in gettext.h
+ nw="$nw -Wswitch-default" # Too many warnings for now
+ nw="$nw -Wunsafe-loop-optimizations" # It's OK to omit unsafe optimizations.
+ nw="$nw -Winline" # It's OK to not inline.
+ nw="$nw -Wstrict-overflow" # It's OK to optimize strictly.
+ nw="$nw -Wsuggest-attribute=pure" # Too many warnings for now.
+
+ gl_MANYWARN_ALL_GCC([ws])
+ gl_MANYWARN_COMPLEMENT([ws], [$ws], [$nw])
+ for w in $ws; do
+ gl_WARN_ADD([$w])
+ done
+ gl_WARN_ADD([-Wno-sign-compare]) # Too many warnings for now
+ gl_WARN_ADD([-Wno-type-limits]) # It's OK to optimize based on types.
+ gl_WARN_ADD([-Wno-unused-parameter]) # Too many warnings for now
+ gl_WARN_ADD([-Wno-format-nonliteral])
+
+ gl_WARN_ADD([-fdiagnostics-show-option])
+ gl_WARN_ADD([-funit-at-a-time])
+
+ AC_SUBST([WARN_CFLAGS])
+
+ AC_DEFINE([lint], [1], [Define to 1 if the compiler is checking for lint.])
+ AH_VERBATIM([FORTIFY_SOURCE],
+ [/* Enable compile-time and run-time bounds-checking, and some warnings,
+ without upsetting glibc 2.15+. */
+ #if !defined _FORTIFY_SOURCE && defined __OPTIMIZE__ && __OPTIMIZE__
+ # define _FORTIFY_SOURCE 2
+ #endif
+ ])
+ AC_DEFINE([GNULIB_PORTCHECK], [1], [enable some gnulib portability checks])
+
+ # Use a slightly smaller set of warning options for lib/.
+ # Remove the following and save the result in GNULIB_WARN_CFLAGS.
+ nw=
+ nw="$nw -Wmissing-prototypes"
+ nw="$nw -Wunused-macros"
+ #
+ # These are for argp.
+ nw="$nw -Wmissing-field-initializers"
+ nw="$nw -Wshadow"
+ #
+ gl_MANYWARN_COMPLEMENT([GNULIB_WARN_CFLAGS], [$WARN_CFLAGS], [$nw])
+
+ # This is also for argp.
+ gl_WARN_ADD([-Wno-missing-field-initializers], [GNULIB_WARN_CFLAGS])
+
+ AC_SUBST([GNULIB_WARN_CFLAGS])
+
+ # For gnulib-tests, the set is slightly smaller still.
+ nw=
+ # It's not worth being this picky about test programs.
+ nw="$nw -Wsuggest-attribute=const"
+ gl_MANYWARN_COMPLEMENT([GNULIB_TEST_WARN_CFLAGS],
+ [$GNULIB_WARN_CFLAGS], [$nw])
+ AC_SUBST([GNULIB_TEST_WARN_CFLAGS])