PR c++/81420 - not extending temporary lifetime.

	* call.c (extend_ref_init_temps_1): Handle ARRAY_REF.
	* class.c (build_base_path): Avoid redundant move of an rvalue.

From-SVN: r260563

gcc/cp/ChangeLog

 2018-05-22  Jason Merrill  <jason@redhat.com>
 
+	PR c++/81420 - not extending temporary lifetime.
+	* call.c (extend_ref_init_temps_1): Handle ARRAY_REF.
+	* class.c (build_base_path): Avoid redundant move of an rvalue.
+
 	PR c++/85866 - error with .* in default template arg.
 	* pt.c (tsubst_copy_and_build): Handle partial instantiation.
 

gcc/cp/call.c

@@ -11061,7 +11061,9 @@ extend_ref_init_temps_1 (tree decl, tree init, vec<tree, va_gc> **cleanups)
   if (TREE_CODE (sub) != ADDR_EXPR)
     return init;
   /* Deal with binding to a subobject.  */
-  for (p = &TREE_OPERAND (sub, 0); TREE_CODE (*p) == COMPONENT_REF; )
+  for (p = &TREE_OPERAND (sub, 0);
+       (TREE_CODE (*p) == COMPONENT_REF
+	|| TREE_CODE (*p) == ARRAY_REF); )
     p = &TREE_OPERAND (*p, 0);
   if (TREE_CODE (*p) == TARGET_EXPR)
     {

gcc/cp/class.c

@@ -426,7 +426,7 @@ build_base_path (enum tree_code code,
     {
       expr = cp_build_fold_indirect_ref (expr);
       expr = build_simple_base_path (expr, binfo);
-      if (rvalue)
+      if (rvalue && lvalue_p (expr))
 	expr = move (expr);
       if (want_pointer)
 	expr = build_address (expr);

gcc/testsuite/g++.dg/cpp0x/temp-extend1.C

+// PR c++/81420
+// { dg-do run { target c++11 } }
+
+int d;
+
+struct A
+{
+  int i[2];
+  ~A() { ++d; };
+};
+
+struct B: A {};
+
+int main()
+{
+  const int &r = B().i[0];
+  if (d != 0)
+    __builtin_abort();
+}