Improve support for out-of-line definitions of nested templates and

their members, including member class template, member function
templates, and member classes and functions of member templates.

To actually parse the nested-name-specifiers that qualify the name of
an out-of-line definition of a member template, e.g.,

  template<typename X> template<typename Y>
  X Outer<X>::Inner1<Y>::foo(Y) {
    return X();
  }

we need to look for the template names (e.g., "Inner1") as a member of
the current instantiation (Outer<X>), even before we have entered the
scope of the current instantiation. Since we can't do this in general
(i.e., we should not be looking into all dependent
nested-name-specifiers as if they were the current instantiation), we
rely on the parser to tell us when it is parsing a declaration
specifier sequence, and, therefore, when we should consider the
current scope specifier to be a current instantiation.

Printing of complicated, dependent nested-name-specifiers may be
somewhat broken by this commit; I'll add tests for this issue and fix
the problem (if it still exists) in a subsequent commit.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@80044 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 82 insertions, 58 deletions

diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 03e641780d..9db3fae036 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -1265,7 +1265,8 @@ public:
                                 LookupNameKind NameKind, 
                                 bool RedeclarationOnly = false,
                                 bool AllowBuiltinCreation = false,
-                                SourceLocation Loc = SourceLocation());
+                                SourceLocation Loc = SourceLocation(),
+                                bool EnteringContext = false);
 
   ObjCProtocolDecl *LookupProtocol(IdentifierInfo *II);
   ObjCCategoryImplDecl *LookupObjCCategoryImpl(IdentifierInfo *II);
@@ -1951,7 +1952,8 @@ public:
                                                   const CXXScopeSpec &SS,
                                                   SourceLocation IdLoc,
                                                   SourceLocation CCLoc,
-                                                  IdentifierInfo &II);
+                                                  IdentifierInfo &II,
+                                                  bool EnteringContext);
 
   /// ActOnCXXNestedNameSpecifier - Called during parsing of a
   /// nested-name-specifier that involves a template-id, e.g.,
@@ -2205,8 +2207,9 @@ public:
   // C++ Templates [C++ 14]
   //
   virtual TemplateNameKind isTemplateName(const IdentifierInfo &II, Scope *S,
-                                          TemplateTy &Template,
-                                          const CXXScopeSpec *SS = 0);
+                                          const CXXScopeSpec *SS,
+                                          bool EnteringContext,
+                                          TemplateTy &Template);
   bool DiagnoseTemplateParameterShadow(SourceLocation Loc, Decl *PrevDecl);
   TemplateDecl *AdjustDeclIfTemplate(DeclPtrTy &Decl);
 
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index 188957176b..9c9bff8a08 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -48,11 +48,11 @@ DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
       return Record;
     
     if (EnteringContext) {
-      // We are entering the context of the nested name specifier, so try to
-      // match the nested name specifier to either a primary class template
-      // or a class template partial specialization.
       if (const TemplateSpecializationType *SpecType
             = dyn_cast_or_null<TemplateSpecializationType>(NNS->getAsType())) {
+        // We are entering the context of the nested name specifier, so try to
+        // match the nested name specifier to either a primary class template
+        // or a class template partial specialization.
         if (ClassTemplateDecl *ClassTemplate 
               = dyn_cast_or_null<ClassTemplateDecl>(
                             SpecType->getTemplateName().getAsTemplateDecl())) {
@@ -74,6 +74,10 @@ DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
                 = ClassTemplate->findPartialSpecialization(ContextType))
             return PartialSpec;
         }
+      } else if (const RecordType *RecordT 
+                   = dyn_cast_or_null<RecordType>(NNS->getAsType())) {
+        // The nested name specifier refers to a member of a class template.
+        return RecordT->getDecl();
       }
       
       std::string NNSString;
@@ -260,17 +264,14 @@ Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
                                                     const CXXScopeSpec &SS,
                                                     SourceLocation IdLoc,
                                                     SourceLocation CCLoc,
-                                                    IdentifierInfo &II) {
+                                                    IdentifierInfo &II,
+                                                    bool EnteringContext) {
   NestedNameSpecifier *Prefix 
     = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
 
-  // If the prefix already refers to an unknown specialization, there
-  // is no name lookup to perform. Just build the resulting
-  // nested-name-specifier.
-  if (Prefix && isUnknownSpecialization(SS))
-    return NestedNameSpecifier::Create(Context, Prefix, &II);
-
-  NamedDecl *SD = LookupParsedName(S, &SS, &II, LookupNestedNameSpecifierName);
+  NamedDecl *SD = LookupParsedName(S, &SS, &II, LookupNestedNameSpecifierName,
+                                   false, false, SourceLocation(),
+                                   EnteringContext);
 
   if (SD) {
     if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD))
@@ -303,13 +304,16 @@ Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
 
     // Fall through to produce an error: we found something that isn't
     // a class or a namespace.
-  }
+  } else if (SS.isSet() && isDependentScopeSpecifier(SS))
+    return NestedNameSpecifier::Create(Context, Prefix, &II);
 
   // If we didn't find anything during our lookup, try again with
   // ordinary name lookup, which can help us produce better error
   // messages.
   if (!SD)
-    SD = LookupParsedName(S, &SS, &II, LookupOrdinaryName);
+    SD = LookupParsedName(S, &SS, &II, LookupOrdinaryName,
+                          false, false, SourceLocation(),
+                          EnteringContext);
   unsigned DiagID;
   if (SD)
     DiagID = diag::err_expected_class_or_namespace;
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 61f0ce808a..d478c048b8 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -72,7 +72,7 @@ Sema::TypeTy *Sema::getTypeName(IdentifierInfo &II, SourceLocation NameLoc,
   // refer to a member of an unknown specialization.
   if (SS && isUnknownSpecialization(*SS))
     return 0;
-
+  
   LookupResult Result 
     = LookupParsedName(S, SS, &II, LookupOrdinaryName, false, false);
 
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 1d583cc391..6627499d12 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -1116,7 +1116,7 @@ Sema::LookupQualifiedName(DeclContext *LookupCtx, DeclarationName Name,
 /// @param S        The scope from which unqualified name lookup will
 /// begin.
 /// 
-/// @param SS       An optional C++ scope-specified, e.g., "::N::M".
+/// @param SS       An optional C++ scope-specifier, e.g., "::N::M".
 ///
 /// @param Name     The name of the entity that name lookup will
 /// search for.
@@ -1125,49 +1125,56 @@ Sema::LookupQualifiedName(DeclContext *LookupCtx, DeclarationName Name,
 /// name lookup. At present, this is only used to produce diagnostics when 
 /// C library functions (like "malloc") are implicitly declared.
 ///
+/// @param EnteringContext Indicates whether we are going to enter the
+/// context of the scope-specifier SS (if present).
+///
 /// @returns The result of qualified or unqualified name lookup.
 Sema::LookupResult
 Sema::LookupParsedName(Scope *S, const CXXScopeSpec *SS, 
                        DeclarationName Name, LookupNameKind NameKind,
                        bool RedeclarationOnly, bool AllowBuiltinCreation,
-                       SourceLocation Loc) {
-  if (SS && (SS->isSet() || SS->isInvalid())) {
-    // If the scope specifier is invalid, don't even look for
+                       SourceLocation Loc,
+                       bool EnteringContext) {
+  if (SS && SS->isInvalid()) {
+    // When the scope specifier is invalid, don't even look for
     // anything.
-    if (SS->isInvalid())
-      return LookupResult::CreateLookupResult(Context, 0);
-
-    assert(!isUnknownSpecialization(*SS) && "Can't lookup dependent types");
-
-    if (isDependentScopeSpecifier(*SS)) {
-      // Determine whether we are looking into the current
-      // instantiation. 
-      NestedNameSpecifier *NNS 
-        = static_cast<NestedNameSpecifier *>(SS->getScopeRep());
-      CXXRecordDecl *Current = getCurrentInstantiationOf(NNS);
-      assert(Current && "Bad dependent scope specifier");
+    return LookupResult::CreateLookupResult(Context, 0);
+  }
+  
+  if (SS && SS->isSet()) {
+    if (DeclContext *DC = computeDeclContext(*SS, EnteringContext)) {
+      // We have resolved the scope specifier to a particular declaration 
+      // contex, and will perform name lookup in that context.
       
-      // We nested name specifier refers to the current instantiation,
-      // so now we will look for a member of the current instantiation
-      // (C++0x [temp.dep.type]).
-      unsigned IDNS = getIdentifierNamespacesFromLookupNameKind(NameKind, true);
-      DeclContext::lookup_iterator I, E;
-      for (llvm::tie(I, E) = Current->lookup(Name); I != E; ++I)
-        if (isAcceptableLookupResult(*I, NameKind, IDNS))
-          return LookupResult::CreateLookupResult(Context, I, E);
+      if (DC->isDependentContext()) {
+        // If this is a dependent context, then we are looking for a member of
+        // the current instantiation. This is a narrow search that looks into
+        // just the described declaration context (C++0x [temp.dep.type]).
+        unsigned IDNS = getIdentifierNamespacesFromLookupNameKind(NameKind, 
+                                                                  true);
+        DeclContext::lookup_iterator I, E;
+        for (llvm::tie(I, E) = DC->lookup(Name); I != E; ++I)
+          if (isAcceptableLookupResult(*I, NameKind, IDNS))
+            return LookupResult::CreateLookupResult(Context, I, E);
+      }
+      
+      // Qualified name lookup into the named declaration context.
+      // The declaration context must be complete.
+      if (RequireCompleteDeclContext(*SS))
+        return LookupResult::CreateLookupResult(Context, 0);
+            
+      return LookupQualifiedName(DC, Name, NameKind, RedeclarationOnly);
     }
 
-    if (RequireCompleteDeclContext(*SS))
-      return LookupResult::CreateLookupResult(Context, 0);
-
-    return LookupQualifiedName(computeDeclContext(*SS),
-                               Name, NameKind, RedeclarationOnly);
+    // We could not resolve the scope specified to a specific declaration
+    // context, which means that SS refers to an unknown specialization. 
+    // Name lookup can't find anything in this case.
+    return LookupResult::CreateLookupResult(Context, 0);
   }
 
-  LookupResult result(LookupName(S, Name, NameKind, RedeclarationOnly, 
-                    AllowBuiltinCreation, Loc));
-  
-  return(result);
+  // Perform unqualified name lookup starting in the given scope. 
+  return LookupName(S, Name, NameKind, RedeclarationOnly, AllowBuiltinCreation, 
+                    Loc);
 }
 
 
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 9dfa96288c..e0798f685b 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -27,10 +27,19 @@ using namespace clang;
 /// passed to indicate the C++ scope in which the identifier will be
 /// found. 
 TemplateNameKind Sema::isTemplateName(const IdentifierInfo &II, Scope *S,
-                                      TemplateTy &TemplateResult,
-                                      const CXXScopeSpec *SS) {
-  NamedDecl *IIDecl = LookupParsedName(S, SS, &II, LookupOrdinaryName);
-
+                                      const CXXScopeSpec *SS,
+                                      bool EnteringContext,
+                                      TemplateTy &TemplateResult) {                                      
+  LookupResult Found = LookupParsedName(S, SS, &II, LookupOrdinaryName, 
+                                        false, false, SourceLocation(),
+                                        EnteringContext);
+  
+  // FIXME: Cope with ambiguous name-lookup results.
+  assert(!Found.isAmbiguous() && 
+         "Cannot handle template name-lookup ambiguities");
+  
+  NamedDecl *IIDecl = Found;
+  
   TemplateNameKind TNK = TNK_Non_template;
   TemplateDecl *Template = 0;
 
@@ -1116,7 +1125,7 @@ Sema::ActOnDependentTemplateName(SourceLocation TemplateKWLoc,
     // "template" keyword is now permitted). We follow the C++0x
     // rules, even in C++03 mode, retroactively applying the DR.
     TemplateTy Template;
-    TemplateNameKind TNK = isTemplateName(Name, 0, Template, &SS);
+    TemplateNameKind TNK = isTemplateName(Name, 0, &SS, false, Template);
     if (TNK == TNK_Non_template) {
       Diag(NameLoc, diag::err_template_kw_refers_to_non_template)
         << &Name;
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 8220ec33c2..5d34e07303 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -4378,7 +4378,8 @@ TreeTransform<Derived>::RebuildNestedNameSpecifier(NestedNameSpecifier *Prefix,
   SS.setScopeRep(Prefix);
   return static_cast<NestedNameSpecifier *>(
                     SemaRef.ActOnCXXNestedNameSpecifier(0, SS, Range.getEnd(), 
-                                                        Range.getEnd(), II));
+                                                        Range.getEnd(), II,
+                                                        false));
 }
 
 template<typename Derived>
@@ -4435,7 +4436,7 @@ TreeTransform<Derived>::RebuildTemplateName(NestedNameSpecifier *Qualifier,
   SS.setRange(SourceRange(getDerived().getBaseLocation()));
   SS.setScopeRep(Qualifier);
   Sema::TemplateTy Template;
-  TemplateNameKind TNK = SemaRef.isTemplateName(II, 0, Template, &SS);
+  TemplateNameKind TNK = SemaRef.isTemplateName(II, 0, &SS, false, Template);
   if (TNK == TNK_Non_template) {
     SemaRef.Diag(getDerived().getBaseLocation(), 
                  diag::err_template_kw_refers_to_non_template)