[PATCH][C++] Fix PR86763, wrong-code with TYPE_TYPELESS_STORAGE

[Richard Biener]

This fixes the PR by making sure CLASSTYPE_AS_BASE types inherit
TYPE_TYPELESS_STORAGE from the main type so that types that inherit
a type with TYPE_TYPELESS_STORAGE also get TYPE_TYPELESS_STORAGE
propagated.

Bootstrap & regtest running on x86_64-unknown-linux-gnu, OK?

Thanks,
Richard.

2018-08-02  Richard Biener  <rguent...@suse.de>

        PR c++/86763
        * class.c (layout_class_type): Copy TYPE_TYPELESS_STORAGE
        to the CLASSTYPE_AS_BASE.

        * g++.dg/torture/pr86763.C: New testcase.

Index: gcc/cp/class.c
===================================================================
--- gcc/cp/class.c      (revision 263209)
+++ gcc/cp/class.c      (working copy)
@@ -6243,6 +6243,7 @@ layout_class_type (tree t, tree *virtual
                                  bitsize_int (BITS_PER_UNIT)));
       SET_TYPE_ALIGN (base_t, rli->record_align);
       TYPE_USER_ALIGN (base_t) = TYPE_USER_ALIGN (t);
+      TYPE_TYPELESS_STORAGE (base_t) = TYPE_TYPELESS_STORAGE (t);
 
       /* Copy the non-static data members of T. This will include its
         direct non-virtual bases & vtable.  */
Index: gcc/testsuite/g++.dg/torture/pr86763.C
===================================================================
--- gcc/testsuite/g++.dg/torture/pr86763.C      (nonexistent)
+++ gcc/testsuite/g++.dg/torture/pr86763.C      (working copy)
@@ -0,0 +1,36 @@
+// { dg-do run }
+// { dg-additional-options "-fschedule-insns2 -fstrict-aliasing" }
+
+#include <cstdint>
+#include <cassert>
+#include <time.h>
+struct ID {
+  uint64_t value;
+};
+uint64_t value(ID id) { return id.value; }
+uint64_t gen { 1000 };
+struct Msg {
+  uint64_t time;
+  ID id;
+};
+struct V {
+  V() { }
+  V(Msg const & msg) : msg(msg) { }
+  Msg & get() { return msg; }
+  Msg msg;
+  char pad[237 - sizeof(Msg)];
+};
+struct T : V { using V::V; };
+Msg init_msg() {
+  Msg msg;
+  timespec t;
+  clock_gettime(CLOCK_REALTIME, &t);
+  msg.time = t.tv_sec + t.tv_nsec;
+  msg.id.value = ++gen;
+  return msg;
+}
+int main() {
+  T t;
+  t = init_msg();
+  assert(value(t.get().id) == 1001);
+}