configure should check for warning flags supported to disable them (#338205).
Configure would check whether gcc supported -Wno... flags. But gcc always
does. It is happy to just not warn about anything. So flip all configure
checks to test for the warning and only when gcc accepts the warning flag
use -Wno-...
Introduces two helper functions to make it easier to add new flag checks.
AC_GCC_WARNING_COND and AC_GCC_WARNING_SUBST_NO.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14319 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/configure.ac b/configure.ac
index 21b7782..a8cba6b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1727,163 +1727,52 @@
AC_SUBST(PREFERRED_STACK_BOUNDARY)
-# does this compiler support -Wno-pointer-sign ?
-AC_MSG_CHECKING([if gcc accepts -Wno-pointer-sign])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-pointer-sign"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
- return 0;
-]])], [
-no_pointer_sign=yes
-AC_MSG_RESULT([yes])
-], [
-no_pointer_sign=no
-AC_MSG_RESULT([no])
-])
+# Convenience function to check whether GCC supports a particular
+# warning option. Takes two arguments, first the warning flag name
+# to check (without -W), then the conditional name to set if that
+# warning flag is supported.
+AC_DEFUN([AC_GCC_WARNING_COND],[
+AC_MSG_CHECKING([if gcc accepts -W$1])
+safe_CFLAGS=$CLFLAGS
+CFLAGS="-W$1"
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[;]])], [
+has_warning_flag=yes
+AC_MSG_RESULT([yes])], [
+has_warning_flag=no
+AC_MSG_RESULT([no])])
CFLAGS=$safe_CFLAGS
+AM_CONDITIONAL([$2], test x$has_warning_flag = xyes)]
+)
-AM_CONDITIONAL(HAS_POINTER_SIGN_WARNING, test x$no_pointer_sign = xyes)
+AC_GCC_WARNING_COND([pointer-sign], [HAS_POINTER_SIGN_WARNING])
+AC_GCC_WARNING_COND([write-strings], [HAS_WRITE_STRINGS_WARNING])
-
-# does this compiler support -Wno-write-strings ?
-AC_MSG_CHECKING([if gcc accepts -Wwrite-strings])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wwrite-strings"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
- return 0;
-]])], [
-no_write_strings=yes
-AC_MSG_RESULT([yes])
-], [
-no_write_strings=no
-AC_MSG_RESULT([no])
-])
+# Convenience function to check whether GCC supports a particular
+# warning option. Similar to AC_GCC_WARNING_COND, but does a
+# substitution instead of setting an conditional. Takes two arguments,
+# first the warning flag name to check (without -W), then the
+# substitution name to set with -Wno-warning-flag if the flag exists,
+# or the empty string if the compiler doesn't accept the flag. Note
+# that checking is done against the warning flag itself, but the
+# substitution is then done to cancel the warning flag.
+AC_DEFUN([AC_GCC_WARNING_SUBST_NO],[
+AC_MSG_CHECKING([if gcc accepts -W$1])
+safe_CFLAGS=$CLFLAGS
+CFLAGS="-W$1"
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[;]])], [
+AC_SUBST([$2], [-Wno-$1])
+AC_MSG_RESULT([yes])], [
+AC_SUBST([$2], [])
+AC_MSG_RESULT([no])])
CFLAGS=$safe_CFLAGS
-
-if test x$no_write_strings = xyes; then
- CFLAGS="$CFLAGS -Wwrite-strings"
- CXXFLAGS="$CXXFLAGS -Wwrite-strings"
-fi
-
-AM_CONDITIONAL(HAS_WRITE_STRINGS_WARNING, test x$no_write_strings = xyes)
-
-# does this compiler support -Wno-empty-body ?
-
-AC_MSG_CHECKING([if gcc accepts -Wno-empty-body])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-empty-body"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
- return 0;
-]])], [
-AC_SUBST([FLAG_W_NO_EMPTY_BODY], [-Wno-empty-body])
-AC_MSG_RESULT([yes])
-], [
-AC_SUBST([FLAG_W_NO_EMPTY_BODY], [])
-AC_MSG_RESULT([no])
])
-CFLAGS=$safe_CFLAGS
-
-# does this compiler support -Wno-format-zero-length ?
-
-AC_MSG_CHECKING([if gcc accepts -Wno-format-zero-length])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-format-zero-length"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
- return 0;
-]])], [
-AC_SUBST([FLAG_W_NO_FORMAT_ZERO_LENGTH], [-Wno-format-zero-length])
-AC_MSG_RESULT([yes])
-], [
-AC_SUBST([FLAG_W_NO_FORMAT_ZERO_LENGTH], [])
-AC_MSG_RESULT([no])
-])
-CFLAGS=$safe_CFLAGS
-
-
-# does this compiler support -Wno-tautological-compare ?
-
-AC_MSG_CHECKING([if gcc accepts -Wno-tautological-compare])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-tautological-compare"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
- return 0;
-]])], [
-AC_SUBST([FLAG_W_NO_TAUTOLOGICAL_COMPARE], [-Wno-tautological-compare])
-AC_MSG_RESULT([yes])
-], [
-AC_SUBST([FLAG_W_NO_TAUTOLOGICAL_COMPARE], [])
-AC_MSG_RESULT([no])
-])
-CFLAGS=$safe_CFLAGS
-
-
-# does this compiler support -Wno-nonnull ?
-
-AC_MSG_CHECKING([if gcc accepts -Wno-nonnull])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-nonnull"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
- return 0;
-]])], [
-AC_SUBST([FLAG_W_NO_NONNULL], [-Wno-nonnull])
-AC_MSG_RESULT([yes])
-], [
-AC_SUBST([FLAG_W_NO_NONNULL], [])
-AC_MSG_RESULT([no])
-])
-CFLAGS=$safe_CFLAGS
-
-
-# does this compiler support -Wno-overflow ?
-
-AC_MSG_CHECKING([if gcc accepts -Wno-overflow])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-overflow"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
- return 0;
-]])], [
-AC_SUBST([FLAG_W_NO_OVERFLOW], [-Wno-overflow])
-AC_MSG_RESULT([yes])
-], [
-AC_SUBST([FLAG_W_NO_OVERFLOW], [])
-AC_MSG_RESULT([no])
-])
-CFLAGS=$safe_CFLAGS
-
-
-# does this compiler support -Wno-uninitialized ?
-
-AC_MSG_CHECKING([if gcc accepts -Wno-uninitialized])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-uninitialized"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
- return 0;
-]])], [
-AC_SUBST([FLAG_W_NO_UNINITIALIZED], [-Wno-uninitialized])
-AC_MSG_RESULT([yes])
-], [
-AC_SUBST([FLAG_W_NO_UNINITIALIZED], [])
-AC_MSG_RESULT([no])
-])
-CFLAGS=$safe_CFLAGS
-
+AC_GCC_WARNING_SUBST_NO([empty-body], [FLAG_W_NO_EMPTY_BODY])
+AC_GCC_WARNING_SUBST_NO([format-zero-length], [FLAG_W_NO_FORMAT_ZERO_LENGTH])
+AC_GCC_WARNING_SUBST_NO([tautological-compare], [FLAG_W_NO_TAUTOLOGICAL_COMPARE])
+AC_GCC_WARNING_SUBST_NO([nonnull], [FLAG_W_NO_NONNULL])
+AC_GCC_WARNING_SUBST_NO([overflow], [FLAG_W_NO_OVERFLOW])
+AC_GCC_WARNING_SUBST_NO([uninitialized], [FLAG_W_NO_UNINITIALIZED])
# does this compiler support -Wextra or the older -W ?