commit 6cdd28bb152fcb07a7eb6c9f053cd435cf719a20
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Nov 16 16:13:25 2016 -0500

    ref

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index c54a2de..87db589 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -6839,7 +6839,8 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
 	  /* Set these flags now for templates.  We'll update the flags in
 	     store_init_value for instantiations.  */
 	  DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl) = 1;
-	  if (decl_maybe_constant_var_p (decl))
+	  if (decl_maybe_constant_var_p (decl)
+	      && TREE_CODE (type) != REFERENCE_TYPE)
 	    TREE_CONSTANT (decl) = 1;
 	}
     }
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 022a478..dcdb710 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -824,7 +824,8 @@ store_init_value (tree decl, tree init, vec<tree, va_gc>** cleanups, int flags)
       const_init = (reduced_constant_expression_p (value)
 		    || error_operand_p (value));
       DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl) = const_init;
-      TREE_CONSTANT (decl) = const_init && decl_maybe_constant_var_p (decl);
+      if (TREE_CODE (type) != REFERENCE_TYPE)
+	TREE_CONSTANT (decl) = const_init && decl_maybe_constant_var_p (decl);
     }
   value = cp_fully_fold (value);