re PR c++/44333 (Ambiguity with typedef and using namespace)

	PR c++/44333
	* name-lookup.c (same_entity_p): New.
	(ambiguous_decl): Multiple declarations of the same entity
	are not ambiguous.

From-SVN: r160183

1 files changed, 26 insertions, 1 deletions

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 051d3c5..936c256 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -3698,6 +3698,31 @@ merge_functions (tree s1, tree s2)
   return s1;
 }
 
+/* Returns TRUE iff OLD and NEW are the same entity.
+
+   3 [basic]/3: An entity is a value, object, reference, function,
+   enumerator, type, class member, template, template specialization,
+   namespace, parameter pack, or this.
+
+   7.3.4 [namespace.udir]/4: If name lookup finds a declaration for a name
+   in two different namespaces, and the declarations do not declare the
+   same entity and do not declare functions, the use of the name is
+   ill-formed.  */
+
+static bool
+same_entity_p (tree one, tree two)
+{
+  if (one == two)
+    return true;
+  if (!one || !two)
+    return false;
+  if (TREE_CODE (one) == TYPE_DECL
+      && TREE_CODE (two) == TYPE_DECL
+      && same_type_p (TREE_TYPE (one), TREE_TYPE (two)))
+    return true;
+  return false;
+}
+
 /* This should return an error not all definitions define functions.
    It is not an error if we find two functions with exactly the
    same signature, only if these are selected in overload resolution.
@@ -3763,7 +3788,7 @@ ambiguous_decl (struct scope_binding *old, cxx_binding *new_binding, int flags)
 
   if (!old->value)
     old->value = val;
-  else if (val && val != old->value)
+  else if (val && !same_entity_p (val, old->value))
     {
       if (is_overloaded_fn (old->value) && is_overloaded_fn (val))
 	old->value = merge_functions (old->value, val);