Implement explicit instantiations of member classes of class templates, e.g.,

  template<typename T>
  struct X {
    struct Inner;
  };

  template struct X<int>::Inner;

This change is larger than it looks because it also fixes some
a problem with nested-name-specifiers and tags. We weren't requiring
the DeclContext associated with the scope specifier of a tag to be
complete. Therefore, when looking for something like "struct
X<int>::Inner", we weren't instantiating X<int>. 

This, naturally, uncovered a problem with member pointers, where we
were requiring the left-hand side of a member pointer access
expression (e.g., x->*) to be a complete type. However, this is wrong:
the semantics of this expression does not require a complete type (EDG
agrees).

Stuart vouched for me. Blame him.

llvm-svn: 71756

1 files changed, 38 insertions, 0 deletions

diff --git a/clang/test/SemaTemplate/temp_explicit.cpp b/clang/test/SemaTemplate/temp_explicit.cpp
index 0b96c73c1f2..6394f1daf47 100644
--- a/clang/test/SemaTemplate/temp_explicit.cpp
+++ b/clang/test/SemaTemplate/temp_explicit.cpp
@@ -71,3 +71,41 @@ void f3(X4<int&>::Inner); // okay, Inner::VeryInner, not instantiated
 
 template struct X4<int&>; // expected-note{{instantiation}}
 template struct X4<float&>; // expected-note{{instantiation}}
+
+// Check explicit instantiation of member classes
+namespace N2 {
+
+template<typename T>
+struct X5 {
+  struct Inner1 {
+    void f(T&);
+  };
+
+  struct Inner2 {
+    struct VeryInner { // expected-note 2{{instantiation}}
+      void g(T*); // expected-error 2{{pointer to a reference}}
+    };
+  };
+};
+
+}
+
+template struct N2::X5<void>::Inner2;
+
+using namespace N2;
+template struct X5<int&>::Inner2; // expected-note{{instantiation}}
+
+void f4(X5<float&>::Inner2);
+template struct X5<float&>::Inner2; // expected-note{{instantiation}}
+
+namespace N3 {
+  template struct N2::X5<int>::Inner2;
+}
+
+struct X6 {
+  struct Inner { // expected-note{{here}}
+    void f();
+  };
+};
+
+template struct X6::Inner; // expected-error{{non-templated}}