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

diff --git a/NEWS b/NEWS
index 27312cc714a8d35eafe439522d9cff3f16524382..d30aabcb9db6dbb2d22d3265a67ac686f86e5b20 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -210,6 +210,7 @@ where XXXXXX is the bug number as listed below.
 338024  inlined functions are not shown if DW_AT_ranges is used
 338115  DRD: computed conflict set differs from actual after fork
 338160  implement display of thread local storage in gdbsrv
+338205  configure.ac and check for -Wno-tautological-compare
 n-i-bz  Fix KVM_CREATE_IRQCHIP ioctl handling
 n-i-bz  s390x: Fix memory corruption for multithreaded applications
 n-i-bz  vex arm->IR: allow PC as basereg in some LDRD cases

diff --git a/configure.ac b/configure.ac
index 21b7782feda6495db3539110a7a4c2eed4223c42..a8cba6b2a475f43541519783a0f4c50586ed8826 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1727,163 +1727,52 @@ CFLAGS=$safe_CFLAGS
 AC_SUBST(PREFERRED_STACK_BOUNDARY)
 
 
-# does this compiler support -Wno-pointer-sign ?
-AC_MSG_CHECKING([if gcc accepts -Wno-pointer-sign])
-
-safe_CFLAGS=$CFLAGS
-CFLAGS="-Wno-pointer-sign"
-
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
-  return 0;
-]])], [
-no_pointer_sign=yes
-AC_MSG_RESULT([yes])
-], [
-no_pointer_sign=no
-AC_MSG_RESULT([no])
-])
-CFLAGS=$safe_CFLAGS
-
-AM_CONDITIONAL(HAS_POINTER_SIGN_WARNING, test x$no_pointer_sign = xyes)
-
-
-# does this compiler support -Wno-write-strings ?
-AC_MSG_CHECKING([if gcc accepts -Wwrite-strings])
-
-safe_CFLAGS=$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])
-])
-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])
-])
+# 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)]
+)
 
-
-# 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])
-])
+AC_GCC_WARNING_COND([pointer-sign], [HAS_POINTER_SIGN_WARNING])
+AC_GCC_WARNING_COND([write-strings], [HAS_WRITE_STRINGS_WARNING])
+
+# 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
-
-
-# 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 ?