[C++ Path/RFC] PR 60265

[Paolo Carlini]

Hi,

this issue is probably easy to resolve, one way or another, but I find 
it rather curious: as the submitted testcase explains, we reject the 
trivial:

enum E { V };

using E::V;

because "'E' is not a namespace", but I don't see anything in C++11 
explicitly outlawing enums. In fact, current clang accept the whole 
using-enum-1.C attached below. Then there is the case of *scoped enums*, 
which are mentioned in negative in C++11 (7.3.3/7), and current clang 
accepts, the whole using-enum-2.C attached below. Anyay, patchlet passes 
testing on x86_64-linux.

Thanks,
Paolo.

/////////////////////
Index: cp/name-lookup.c
===================================================================
--- cp/name-lookup.c    (revision 211466)
+++ cp/name-lookup.c    (working copy)
@@ -2487,7 +2487,7 @@ validate_nonmember_using_decl (tree decl, tree sco
        member-declaration.  */
   if (TYPE_P (scope))
     {
-      error ("%qT is not a namespace", scope);
+      error ("%qT is not a namespace or unscoped enum", scope);
       return NULL_TREE;
     }
   else if (scope == error_mark_node)
Index: cp/parser.c
===================================================================
--- cp/parser.c (revision 211467)
+++ cp/parser.c (working copy)
@@ -16022,6 +16022,8 @@ cp_parser_using_declaration (cp_parser* parser,
                                                  /*is_declaration=*/true);
   if (!qscope)
     qscope = global_namespace;
+  else if (UNSCOPED_ENUM_P (qscope))
+    qscope = CP_TYPE_CONTEXT (qscope);
 
   if (access_declaration_p && cp_parser_error_occurred (parser))
     /* Something has already gone wrong; there's no need to parse
Index: testsuite/g++.dg/cpp0x/using-enum-1.C
===================================================================
--- testsuite/g++.dg/cpp0x/using-enum-1.C       (revision 0)
+++ testsuite/g++.dg/cpp0x/using-enum-1.C       (working copy)
@@ -0,0 +1,20 @@
+// PR c++/60265
+// { dg-do compile { target c++11 } }
+
+namespace A
+{
+  enum E { V };
+
+  using E::V;
+}
+
+void foo()
+{
+  using A::E::V;
+}
+
+using A::E::V;
+
+enum F { U };
+
+using F::U;
Index: testsuite/g++.dg/cpp0x/using-enum-2.C
===================================================================
--- testsuite/g++.dg/cpp0x/using-enum-2.C       (revision 0)
+++ testsuite/g++.dg/cpp0x/using-enum-2.C       (working copy)
@@ -0,0 +1,20 @@
+// PR c++/60265
+// { dg-do compile { target c++11 } }
+
+namespace A
+{
+  enum class E { V };
+
+  using E::V;        // { dg-error "not a namespace or unscoped enum" }
+}
+
+void foo()
+{
+  using A::E::V;     // { dg-error "not a namespace or unscoped enum" }
+}
+
+using A::E::V;       // { dg-error "not a namespace or unscoped enum" }
+
+enum class F { U };
+
+using F::U;          // { dg-error "not a namespace or unscoped enum" }