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

[Szabolcs Nagy]

On 02/08/18 09:30, Richard Biener wrote:

--- 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);

this fails on targets without clock_gettime (baremetal)
or targets that need -lrt at link time.

can we use something else here?
e.g. time(&t) works on baremetal and does not depend on -lrt.

+  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);
+}