C++ PATCH to add test for c++/79781

[Marek Polacek]

This one was fixed by r246607.  Not adding it to c-c++-common/ because
the C FE generates an error.

Tested x86_64-linux, applying to trunk.

2019-06-20  Marek Polacek  <pola...@redhat.com>

        PR c++/79781
        * g++.dg/ext/goto1.C: New test.

diff --git gcc/testsuite/g++.dg/ext/goto1.C gcc/testsuite/g++.dg/ext/goto1.C
new file mode 100644
index 00000000000..84bbfce6376
--- /dev/null
+++ gcc/testsuite/g++.dg/ext/goto1.C
@@ -0,0 +1,9 @@
+// PR c++/79781
+// { dg-do compile { target int128 } }
+// { dg-options "" }
+
+void c() {
+  static __int128_t d = (long)&&a - (long)&&b;
+a:
+b:;
+}