From 64792e021dc387832f74f566495e80df3c084d7f Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Wed, 2 Sep 2009 23:58:38 +0000
Subject: [PATCH] Add a wicked little test-case that illustrates what we have
 to deal with to properly support member access expressions in templates. This
 test is XFAIL'd, because we get it completely wrong, but I've made the
 minimal changes to the representation to at least avoid a crash.

llvm-svn: 80856
---
 clang/include/clang/AST/NestedNameSpecifier.h |  8 ++++
 clang/lib/AST/NestedNameSpecifier.cpp         | 12 ++++-
 clang/lib/Sema/SemaCXXScopeSpec.cpp           |  6 ++-
 .../test/SemaTemplate/member-access-expr.cpp  | 48 +++++++++++++++++++
 4 files changed, 72 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/SemaTemplate/member-access-expr.cpp

diff --git a/clang/include/clang/AST/NestedNameSpecifier.h b/clang/include/clang/AST/NestedNameSpecifier.h
index 0c31dbbf1ab6..5c76064ae139 100644
--- a/clang/include/clang/AST/NestedNameSpecifier.h
+++ b/clang/include/clang/AST/NestedNameSpecifier.h
@@ -113,6 +113,14 @@ public:
                                      NestedNameSpecifier *Prefix, 
                                      bool Template, Type *T);
 
+  /// \brief Builds a specifier that consists of just an identifier.
+  ///
+  /// The nested-name-specifier is assumed to be dependent, but has no
+  /// prefix because the prefix is implied by something outside of the
+  /// nested name specifier, e.g., in "x->Base::f", the "x" has a dependent
+  /// type.
+  static NestedNameSpecifier *Create(ASTContext &Context, IdentifierInfo *II);
+  
   /// \brief Returns the nested name specifier representing the global
   /// scope.
   static NestedNameSpecifier *GlobalSpecifier(ASTContext &Context);
diff --git a/clang/lib/AST/NestedNameSpecifier.cpp b/clang/lib/AST/NestedNameSpecifier.cpp
index 0376f9db6be0..0c24c89b2917 100644
--- a/clang/lib/AST/NestedNameSpecifier.cpp
+++ b/clang/lib/AST/NestedNameSpecifier.cpp
@@ -75,7 +75,17 @@ NestedNameSpecifier::Create(ASTContext &Context, NestedNameSpecifier *Prefix,
   Mockup.Specifier = T;
   return FindOrInsert(Context, Mockup);
 }
-  
+
+NestedNameSpecifier *
+NestedNameSpecifier::Create(ASTContext &Context, IdentifierInfo *II) {
+  assert(II && "Identifier cannot be NULL");
+  NestedNameSpecifier Mockup;
+  Mockup.Prefix.setPointer(0);
+  Mockup.Prefix.setInt(Identifier);
+  Mockup.Specifier = II;
+  return FindOrInsert(Context, Mockup);
+}
+
 NestedNameSpecifier *NestedNameSpecifier::GlobalSpecifier(ASTContext &Context) {
   if (!Context.GlobalNestedNameSpecifier)
     Context.GlobalNestedNameSpecifier = new (Context, 4) NestedNameSpecifier();
diff --git a/clang/lib/Sema/SemaCXXScopeSpec.cpp b/clang/lib/Sema/SemaCXXScopeSpec.cpp
index 251ffea925c7..352e553edb01 100644
--- a/clang/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/clang/lib/Sema/SemaCXXScopeSpec.cpp
@@ -357,7 +357,8 @@ Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
       // unqualified name lookup in the given scope.
       
       // FIXME: When we're instantiating a template, do we actually have to
-      // look in the scope of the template? Seems fishy...
+      // look in the scope of the template? Both EDG and GCC do it; GCC 
+      // requires the lookup to be successful, EDG doesn't.
       Found = LookupName(S, &II, LookupNestedNameSpecifierName);
       ObjectTypeSearchedInScope = true;
     }
@@ -366,6 +367,9 @@ Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
     // base object type or prior nested-name-specifier, so this 
     // nested-name-specifier refers to an unknown specialization. Just build
     // a dependent nested-name-specifier.
+    if (!Prefix)
+      return NestedNameSpecifier::Create(Context, &II);
+    
     return NestedNameSpecifier::Create(Context, Prefix, &II);
   } else {
     // Perform unqualified name lookup in the current scope.
diff --git a/clang/test/SemaTemplate/member-access-expr.cpp b/clang/test/SemaTemplate/member-access-expr.cpp
new file mode 100644
index 000000000000..f41dc2120abd
--- /dev/null
+++ b/clang/test/SemaTemplate/member-access-expr.cpp
@@ -0,0 +1,48 @@
+// RUN: clang-cc -fsyntax-only -verify %s
+// XFAIL
+template<typename T>
+void call_f0(T x) {
+  x.Base::f0();
+}
+
+struct Base {
+  void f0();
+};
+
+struct X0 : Base { 
+  typedef Base CrazyBase;
+};
+
+void test_f0(X0 x0) {
+  call_f0(x0);
+}
+
+template<typename TheBase, typename T>
+void call_f0_through_typedef(T x) {
+  typedef TheBase Base2;
+  x.Base2::f0();
+}
+
+void test_f0_through_typedef(X0 x0) {
+  call_f0_through_typedef<Base>(x0);
+}
+
+template<typename TheBase, typename T>
+void call_f0_through_typedef2(T x) {
+  typedef TheBase CrazyBase; // expected-note{{current scope}}
+  x.CrazyBase::f0(); // expected-error{{ambiguous}}
+}
+
+struct OtherBase { };
+
+struct X1 : Base, OtherBase { 
+  typedef OtherBase CrazyBase; // expected-note{{object type}}
+};
+
+void test_f0_through_typedef2(X0 x0, X1 x1) {
+  call_f0_through_typedef2<Base>(x0);
+  call_f0_through_typedef2<OtherBase>(x1);
+  call_f0_through_typedef2<Base>(x1); // expected-note{{here}}
+}
+
+