enable -Woverloaded-virtual when available

gcc/
	* configure.ac: Check for -Woverloaded-virtual and enable it if found.
	* configure: Regenerate.

From-SVN: r209480

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2014-04-17  Trevor Saunders  <tsaunders@mozilla.com>
+
+	* configure.ac: Check for -Woverloaded-virtual and enable it if found.
+	* configure: Regenerate.
+
 2014-04-17  Trevor Saunders  <tsaunders@mozilla.com>
 	
 	* passes.c (dump_one_pass): don't check pass->has_gate.

gcc/configure

@@ -6427,6 +6427,50 @@ fi
   done
 CFLAGS="$save_CFLAGS"
 
+save_CFLAGS="$CFLAGS"
+for real_option in -Woverloaded-virtual; do
+  # Do the check with the no- prefix removed since gcc silently
+  # accepts any -Wno-* option on purpose
+  case $real_option in
+    -Wno-*) option=-W`expr x$real_option : 'x-Wno-\(.*\)'` ;;
+    *) option=$real_option ;;
+  esac
+  as_acx_Woption=`$as_echo "acx_cv_prog_cc_warning_$option" | $as_tr_sh`
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC supports $option" >&5
+$as_echo_n "checking whether $CC supports $option... " >&6; }
+if { as_var=$as_acx_Woption; eval "test \"\${$as_var+set}\" = set"; }; then :
+  $as_echo_n "(cached) " >&6
+else
+  CFLAGS="$option"
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  eval "$as_acx_Woption=yes"
+else
+  eval "$as_acx_Woption=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+eval ac_res=\$$as_acx_Woption
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+  if test `eval 'as_val=${'$as_acx_Woption'};$as_echo "$as_val"'` = yes; then :
+  strict_warn="$strict_warn${strict_warn:+ }$real_option"
+fi
+  done
+CFLAGS="$save_CFLAGS"
+
 c_strict_warn=
 save_CFLAGS="$CFLAGS"
 for real_option in -Wold-style-definition -Wc++-compat; do
@@ -17927,7 +17971,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 17930 "configure"
+#line 17974 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -18033,7 +18077,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18036 "configure"
+#line 18080 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H

gcc/configure.ac

@@ -339,6 +339,8 @@ ACX_PROG_CC_WARNING_OPTS(
 	[c_loose_warn])
 ACX_PROG_CC_WARNING_OPTS(
 	m4_quote(m4_do([-Wmissing-format-attribute])), [strict_warn])
+ACX_PROG_CC_WARNING_OPTS(
+	m4_quote(m4_do([-Woverloaded-virtual])), [strict_warn])
 ACX_PROG_CC_WARNING_OPTS(
 	m4_quote(m4_do([-Wold-style-definition -Wc++-compat])), [c_strict_warn])
 ACX_PROG_CC_WARNING_ALMOST_PEDANTIC(