[PATCH, c++] Add testcase from PR68348 to the testsuite

[Uros Bizjak]

This patch adds the test for the fixed PR.

2015-12-09  Uros Bizjak  <ubiz...@gmail.com>

    PR c++/68348
    PR c++/68464
    * g++.dg/pr68348.C: New test.

Tested on x86_64-linux-gnu.

OK for mainline?

Uros.

Index: g++.dg/pr68348.C
===================================================================
--- g++.dg/pr68348.C    (revision 0)
+++ g++.dg/pr68348.C    (revision 0)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c++11 -O2" } */
+
+struct C {
+  constexpr C ():w (), x (), y () {}
+  constexpr double fn () const noexcept;
+  double w;
+  double x;
+  double y;
+};
+
+constexpr double C::fn () const noexcept { return w; }
+
+C foo ()
+{
+  C c;
+  c.fn ();
+  return c;
+}