PR c++/79470 - partial ordering with reference parameters

	* pt.c (unify) [INDIRECT_REF]: Handle pack expansions.

From-SVN: r245589

gcc/cp/ChangeLog

 2017-02-19  Jason Merrill  <jason@redhat.com>
 
+	PR c++/79470 - partial ordering with reference parameters
+	* pt.c (unify) [INDIRECT_REF]: Handle pack expansions.
+
 	PR c++/79500 - ICE with non-template deduction guide
 	* pt.c (do_class_deduction): Use STRIP_TEMPLATE rather than
 	DECL_TEMPLATE_RESULT.

gcc/cp/pt.c

@@ -20918,8 +20918,13 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict,
     case INDIRECT_REF:
       if (REFERENCE_REF_P (parm))
 	{
+	  bool pexp = PACK_EXPANSION_P (arg);
+	  if (pexp)
+	    arg = PACK_EXPANSION_PATTERN (arg);
 	  if (REFERENCE_REF_P (arg))
 	    arg = TREE_OPERAND (arg, 0);
+	  if (pexp)
+	    arg = make_pack_expansion (arg);
 	  return unify (tparms, targs, TREE_OPERAND (parm, 0), arg,
 			strict, explain_p);
 	}

gcc/testsuite/g++.dg/cpp0x/variadic-ref1.C

+// PR c++/79470
+// { dg-do compile { target c++11 } }
+
+    template < const int&... > struct AA;
+
+    template < > struct AA<> { };
+
+    template < const int& II, const int&... Is >
+    struct AA<II,Is...> { };
+