[committed] c++: Add testcase for already fixed PR [PR84689]

[Patrick Palka via Gcc-patches]

We correctly accept this testcase since r11-1638.

gcc/testsuite/ChangeLog:

        PR c++/84689
        * g++.dg/cpp0x/sfinae67.C: New test.
---
 gcc/testsuite/g++.dg/cpp0x/sfinae67.C | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/sfinae67.C

diff --git a/gcc/testsuite/g++.dg/cpp0x/sfinae67.C 
b/gcc/testsuite/g++.dg/cpp0x/sfinae67.C
new file mode 100644
index 00000000000..cfed92ad472
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/sfinae67.C
@@ -0,0 +1,20 @@
+// PR c++/84689
+// { dg-do compile { target c++11 } }
+
+struct base {
+  void operator()();
+};
+
+struct a : base { };
+struct b : base { };
+
+struct f : a, b {
+  using a::operator();
+  using b::operator();
+};
+
+template <class T> auto g(int) -> decltype(T()());
+template <class T> auto g(...) -> int;
+
+using type = decltype(g<f>(0));
+using type = int;
-- 
2.31.1.362.g311531c9de