Check that this cannot be used in a default argument. Happily, it was already implemented

llvm-svn: 58649
diff --git a/clang/test/SemaCXX/default2.cpp b/clang/test/SemaCXX/default2.cpp
index d3e999c..89eb467 100644
--- a/clang/test/SemaCXX/default2.cpp
+++ b/clang/test/SemaCXX/default2.cpp
@@ -36,3 +36,7 @@
   void (*f2)(int = 17)  // {expected-error {{default arguments can only be specified}}}
     = (void (*)(int = 42))f; // {expected-error {{default arguments can only be specified}}}
 }
+
+class X {
+  void f(X* x = this); // expected-error{{invalid use of 'this' outside of a nonstatic member function}}
+};