re PR c++/85976 (ICE in cp_tree_equal when building Blitz. May be nested templates.)

	PR c++/85976
	* tree.c (cp_tree_equal): Handle USING_DECL.

	* g++.dg/cpp0x/alias-decl-64.C: New test.

From-SVN: r261200

gcc/cp/ChangeLog

+2018-06-05  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/85976
+	* tree.c (cp_tree_equal): Handle USING_DECL.
+
 2018-06-05  Jason Merrill  <jason@redhat.com>
 
 	PR c++/85731 - wrong error with qualified-id in template.

gcc/cp/tree.c

@@ -3878,6 +3878,14 @@ cp_tree_equal (tree t1, tree t2)
 				     DEFERRED_NOEXCEPT_ARGS (t2)));
       break;
 
+    case USING_DECL:
+      if (DECL_DEPENDENT_P (t1) && DECL_DEPENDENT_P (t2))
+	return (cp_tree_equal (USING_DECL_SCOPE (t1),
+			       USING_DECL_SCOPE (t2))
+		&& cp_tree_equal (DECL_NAME (t1),
+				  DECL_NAME (t2)));
+      return false;
+
     default:
       break;
     }

gcc/testsuite/ChangeLog

+2018-06-05  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/85976
+	* g++.dg/cpp0x/alias-decl-64.C: New test.
+
 2018-06-05  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/86046

gcc/testsuite/g++.dg/cpp0x/alias-decl-64.C

+// PR c++/85976
+// { dg-do compile { target c++11 } }
+
+template <int> class A;
+template <typename> class B;
+template <typename> struct C;
+template <typename P_expr> class D {
+  using B<typename P_expr::T_numtype>::rank_;
+  void operator()(typename C<A<rank_>>::i);
+};
+
+template <typename P_expr> class F {
+  using B<typename P_expr::T_numtype>::rank_;
+  void operator()(typename C<A<rank_>>::i);
+};