re PR c++/48780 ([C++0x] scoped enumerations and va_arg (default argument promotions))

	PR c++/48780
	* cvt.c (type_promotes_to): Don't promote scoped enums.

From-SVN: r174005

gcc/common.opt

@@ -759,6 +759,9 @@ Driver Undocumented
 ;    function parameters used in other parameters and the return type.
 ;    First selectable in G++ 4.6.
 ;
+; 6: The version of the ABI that doesn't promote scoped enums to int.
+;    First selectable in G++ 4.7.
+;
 ; Additional positive integers will be assigned as new versions of
 ; the ABI become the default version of the ABI.
 fabi-version=

gcc/cp/ChangeLog

 2011-05-20  Jason Merrill  <jason@redhat.com>
 
+	PR c++/48780
+	* cvt.c (type_promotes_to): Don't promote scoped enums.
+
 	PR c++/49066
 	* decl.c (duplicate_decls): Preserve DECL_DELETED_FN.
 

gcc/cp/cvt.c

@@ -1616,6 +1616,10 @@ type_promotes_to (tree type)
   if (TREE_CODE (type) == BOOLEAN_TYPE)
     type = integer_type_node;
 
+  /* scoped enums don't promote.  */
+  else if (SCOPED_ENUM_P (type) && abi_version_at_least (6))
+    ;
+
   /* Normally convert enums to int, but convert wide enums to something
      wider.  */
   else if (TREE_CODE (type) == ENUMERAL_TYPE
@@ -1626,6 +1630,9 @@ type_promotes_to (tree type)
       int precision = MAX (TYPE_PRECISION (type),
 			   TYPE_PRECISION (integer_type_node));
       tree totype = c_common_type_for_size (precision, 0);
+      if (SCOPED_ENUM_P (type))
+	warning (OPT_Wabi, "scoped enum %qT will not promote to an integral "
+		 "type in a future version of GCC", type);
       if (TREE_CODE (type) == ENUMERAL_TYPE)
 	type = ENUM_UNDERLYING_TYPE (type);
       if (TYPE_UNSIGNED (type)

gcc/doc/invoke.texi

@@ -1839,6 +1839,8 @@ Version 5 corrects the mangling of attribute const/volatile on
 function pointer types, decltype of a plain decl, and use of a
 function parameter in the declaration of another parameter.
 
+Version 6 corrects the promotion behavior of C++0x scoped enums.
+
 See also @option{-Wabi}.
 
 @item -fno-access-control

gcc/testsuite/ChangeLog

+2011-05-20  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/cpp0x/enum12.C: New.
+	* g++.dg/cpp0x/enum13.C: New.
+
 2011-05-21  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/48699

gcc/testsuite/g++.dg/cpp0x/enum12.C

+// PR c++/48780
+// { dg-options "-std=c++0x -fabi-version=0" }
+
+typedef __builtin_va_list __gnuc_va_list;
+typedef __gnuc_va_list va_list;
+
+enum struct A : short { X };
+
+void foo(int x, ...) {
+   va_list vl;
+   __builtin_va_start(vl, x);
+   enum A t = __builtin_va_arg(vl, enum A);
+   __builtin_va_end(vl);
+}
+
+int main() {
+   foo(0, A::X);
+}

gcc/testsuite/g++.dg/cpp0x/enum13.C

+// PR c++/48780
+// { dg-options "-std=c++0x -fabi-version=5 -Wabi" }
+
+typedef __builtin_va_list __gnuc_va_list;
+typedef __gnuc_va_list va_list;
+
+enum struct A : short { X };
+
+void foo(int x, ...) {
+   va_list vl;
+   __builtin_va_start(vl, x);
+   enum A t = __builtin_va_arg(vl, enum A); // { dg-warning "promote" }
+   __builtin_va_end(vl);
+}
+
+int main() {
+   foo(0, A::X);		// { dg-warning "will not promote" }
+}
+
+// { dg-prune-output "note" }