Add a test for a subtle instantiation pattern that showed up within a Boost

miscompile reduction. Clang already handles this correctly, but let's make sure
it stays that way.

llvm-svn: 103463

clang/test/SemaTemplate/instantiate-overload-candidates.cpp

@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// This is the function actually selected during overload resolution, and the
+// only one defined.
+template <typename T> void f(T*, int) {}
+
+template <typename T> struct S;
+template <typename T> struct S_ : S<T> { typedef int type; }; // expected-note{{in instantiation}}
+template <typename T> struct S {
+  // Force T to have a complete type here so we can observe instantiations with
+  // incomplete types.
+  T t; // expected-error{{field has incomplete type}}
+};
+
+// Provide a bad class and an overload that instantiates templates with it.
+class NoDefinition; // expected-note{{forward declaration}}
+template <typename T> S_<NoDefinition>::type f(T*, NoDefinition*); // expected-note{{in instantiation}}
+
+void test(int x) {
+  f(&x, 0);
+}