PR c++/81359 - Unparsed NSDMI error from SFINAE context.

	* method.c (synthesized_method_walk): Don't diagnose lack of
	operator delete.

From-SVN: r251036

gcc/cp/ChangeLog

 2017-08-10  Jason Merrill  <jason@redhat.com>
 
+	PR c++/81359 - Unparsed NSDMI error from SFINAE context.
+	* method.c (synthesized_method_walk): Don't diagnose lack of
+	operator delete.
+
 	PR c++/80452 - Core 1579, implicit move semantics on return/throw
 	* cp-tree.h (LOOKUP_PREFER_RVALUE): Now means that we've already
 	tentatively changed the lvalue to an rvalue.

gcc/cp/method.c

@@ -1693,12 +1693,18 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
 
       if (check_vdtor && type_has_virtual_destructor (BINFO_TYPE (base_binfo)))
 	{
-	  fn = locate_fn_flags (ctype, cp_operator_id (DELETE_EXPR),
-				ptr_type_node, flags, complain);
 	  /* Unlike for base ctor/op=/dtor, for operator delete it's fine
 	     to have a null fn (no class-specific op delete).  */
-	  if (fn && fn == error_mark_node && deleted_p)
-	    *deleted_p = true;
+	  fn = locate_fn_flags (ctype, cp_operator_id (DELETE_EXPR),
+				ptr_type_node, flags, tf_none);
+	  if (fn && fn == error_mark_node)
+	    {
+	      if (complain & tf_error)
+		locate_fn_flags (ctype, cp_operator_id (DELETE_EXPR),
+				 ptr_type_node, flags, complain);
+	      if (deleted_p)
+		*deleted_p = true;
+	    }
 	  check_vdtor = false;
 	}
     }

gcc/testsuite/g++.dg/inherit/vdtor1.C

+struct A {
+  void operator delete(void *, unsigned long);
+};
+struct B : A {
+  virtual ~B();
+};
+struct C : B {};