2017-05-30  Jakub Jelinek  <jakub@redhat.com>

 	Backported from mainline

	2016-09-16  Jakub Jelinek  <jakub@redhat.com>

	PR c++/77375

	* class.c (check_bases): Set CLASSTYPE_HAS_MUTABLE if any

	TYPE_HAS_MUTABLE_P for any bases.

	* g++.dg/cpp0x/mutable1.C: New test.

--- gcc/cp/class.c	2017-10-17 17:27:32.287980595 +0200

+++ gcc/cp/class.c	2017-10-17 17:29:11.104213281 +0200

@@ -1479,6 +1479,8 @@ check_bases (tree t,

 	|= CLASSTYPE_CONTAINS_EMPTY_CLASS_P (basetype);

       TYPE_HAS_COMPLEX_DFLT (t) |= (!TYPE_HAS_DEFAULT_CONSTRUCTOR (basetype)

 				    || TYPE_HAS_COMPLEX_DFLT (basetype));

+      if (TYPE_HAS_MUTABLE_P (basetype))

+	CLASSTYPE_HAS_MUTABLE (t) = 1;

       /*  A standard-layout class is a class that:

 	  ...

--- /dev/null

+++ gcc/testsuite/g++.dg/cpp0x/mutable1.C

@@ -0,0 +1,12 @@

+// PR c++/77375

+// { dg-do run { target c++11 } }

+

+struct Base { mutable int i; };

+struct Derived : Base {};

+const Derived foo{};

+

+int

+main ()

+{

+  foo.i = 42;

+}