[PATCH] Fix PR c++/60994 gcc does not recognize hidden/shadowed enumeration as valid nested-name-specifier

[Momchil Velikov]

Hello,

gcc version 4.10.0 20140428 (experimental) (GCC)

Compiling (with c++ -c -std=c++11 b.cc) the following program

enum struct A
{
  n = 3
};

int
foo()
{
  int A;
  return A::n;
}

results in the error:

b.cc: In function 'int foo()':
b.cc:10:10: error: 'A' is not a class, namespace, or enumeration
   return A::n;
          ^
According to the C++11 Standard, [basic.lookup.qual] #1

"If a :: scope resolution operator in a nested-name-specifier is not
preceded by a decltype-specifier, lookup of the name preceding that ::
considers only namespaces, types, and templates whose specializations
are types."

GCC ought not to resolve "A" to the local variable, but to the
enumeration type. This is very similar to the example in the standard

struct A
{
  static int n;
};

int
foo()
{
  int A;
  return A::n;
}

which is compiled correctly by GCC, though.


Please, review this proposed fix. Bootstrapped/regtested for C/C++ on
x86_64-unknown-linux-gnu.

~chill

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a5f3829..36c07a6 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2014-04-29  Momchil Velikov  <momchil.veli...@gmail.com>
+
+       PR c++/60994
+       * parser.c (cp_parser_class_name): Allow enumeral type as a
+       nested-name-specifier
+
 2014-04-28  Paolo Carlini  <paolo.carl...@oracle.com>
 
        PR c++/59120
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 962cace..460535e 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -19218,7 +19218,8 @@ cp_parser_class_name (cp_parser *parser,
     }
   else if (TREE_CODE (decl) != TYPE_DECL
           || TREE_TYPE (decl) == error_mark_node
-          || !MAYBE_CLASS_TYPE_P (TREE_TYPE (decl))
+          || !(MAYBE_CLASS_TYPE_P (TREE_TYPE (decl))
+                || TREE_CODE (TREE_TYPE (decl)) == ENUMERAL_TYPE)
           /* In Objective-C 2.0, a classname followed by '.' starts a
              dot-syntax expression, and it's not a type-name.  */
           || (c_dialect_objc ()
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b2f07c6..0d9468e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-04-29  Momchil Velikov  <momchil.veli...@gmail.com>
+
+       PR c++/60994
+       * g++.dg/cpp0x/scoped_enum3.C: New testcase.
+
 2014-04-28  Martin Jambor  <mjam...@suse.cz>
 
         * gcc.dg/tree-ssa/sra-14.c: New test.
diff --git a/gcc/testsuite/g++.dg/cpp0x/scoped_enum3.C 
b/gcc/testsuite/g++.dg/cpp0x/scoped_enum3.C
new file mode 100644
index 0000000..ba527cb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/scoped_enum3.C
@@ -0,0 +1,12 @@
+// { dg-do compile { target c++11 } }
+enum struct A
+{
+  n = 3
+};
+
+int
+foo()
+{
+  int A;
+  return A::n; // { dg-error "cannot convert 'A' to 'int' in return" }
+}