decl.c (check_redeclaration_exception_specification): Depend on -Wsystem-headers rather than -pedantic.

* decl.c (check_redeclaration_exception_specification): Depend on
	-Wsystem-headers rather than -pedantic.

From-SVN: r223778

gcc/cp/ChangeLog

@@ -1,5 +1,8 @@
 2015-05-27  Jason Merrill  <jason@redhat.com>
 
+	* decl.c (check_redeclaration_exception_specification): Depend on
+	-Wsystem-headers rather than -pedantic.
+
 	* decl.c (warn_extern_redeclared_static): Use the location of
 	newdecl in diagnostics, not input_location.
 	(validate_constexpr_redeclaration): Likewise.

gcc/cp/decl.c

@@ -1213,14 +1213,19 @@ check_redeclaration_exception_specification (tree new_decl,
      all declarations, including the definition and an explicit
      specialization, of that function shall have an
      exception-specification with the same set of type-ids.  */
-  if ((pedantic || ! DECL_IN_SYSTEM_HEADER (old_decl))
-      && ! DECL_IS_BUILTIN (old_decl)
+  if (! DECL_IS_BUILTIN (old_decl)
       && flag_exceptions
       && !comp_except_specs (new_exceptions, old_exceptions, ce_normal))
     {
-      error ("declaration of %q+F has a different exception specifier",
-	     new_decl);
-      inform (0, "from previous declaration %q+F", old_decl);
+      const char *msg
+	= "declaration of %q+F has a different exception specifier";
+      bool complained = true;
+      if (! DECL_IN_SYSTEM_HEADER (old_decl))
+	error (msg, new_decl);
+      else
+	complained = pedwarn (0, OPT_Wsystem_headers, msg, new_decl);
+      if (complained)
+	inform (0, "from previous declaration %q+F", old_decl);
     }
 }
 

gcc/testsuite/g++.dg/warn/Wsystem-headers1.C

@@ -0,0 +1,3 @@
+#include <stdlib.h>
+
+extern double atof (const char *);

gcc/testsuite/g++.dg/warn/Wsystem-headers1a.C

@@ -0,0 +1,6 @@
+// { dg-do compile { target *-*-*gnu } }
+// { dg-options "-Wsystem-headers" }
+
+#include <stdlib.h>
+
+extern double atof (const char *); // { dg-warning "different exception spec" }