Teach NestedNameSpecifier to keep track of namespace aliases the same

way it keeps track of namespaces. Previously, we would map from the
namespace alias to its underlying namespace when building a
nested-name-specifier, losing source information in the process.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126358 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 47 insertions, 4 deletions

diff --git a/lib/Sema/DeclSpec.cpp b/lib/Sema/DeclSpec.cpp
index 39984974bf..f21d90f7c8 100644
--- a/lib/Sema/DeclSpec.cpp
+++ b/lib/Sema/DeclSpec.cpp
@@ -74,6 +74,15 @@ void CXXScopeSpec::Extend(ASTContext &Context, NamespaceDecl *Namespace,
   Range.setEnd(ColonColonLoc);
 }
 
+void CXXScopeSpec::Extend(ASTContext &Context, NamespaceAliasDecl *Alias,
+                          SourceLocation AliasLoc, 
+                          SourceLocation ColonColonLoc) {
+  ScopeRep = NestedNameSpecifier::Create(Context, ScopeRep, Alias);
+  if (Range.getBegin().isInvalid())
+    Range.setBegin(AliasLoc);
+  Range.setEnd(ColonColonLoc);
+}
+
 void CXXScopeSpec::MakeGlobal(ASTContext &Context, 
                               SourceLocation ColonColonLoc) {
   assert(!ScopeRep && "Already have a nested-name-specifier!?");
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index 754c52cc4a..9daec58d4e 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -139,6 +139,9 @@ DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
   case NestedNameSpecifier::Namespace:
     return NNS->getAsNamespace();
 
+  case NestedNameSpecifier::NamespaceAlias:
+    return NNS->getAsNamespaceAlias()->getNamespace();
+
   case NestedNameSpecifier::TypeSpec:
   case NestedNameSpecifier::TypeSpecWithTemplate: {
     const TagType *Tag = NNS->getAsType()->getAs<TagType>();
@@ -532,11 +535,8 @@ bool Sema::BuildCXXNestedNameSpecifier(Scope *S,
       return false;
     }
 
-    // FIXME: It would be nice to maintain the namespace alias name, then
-    // see through that alias when resolving the nested-name-specifier down to
-    // a declaration context.
     if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD)) {
-      SS.Extend(Context, Alias->getNamespace(), IdentifierLoc, CCLoc);
+      SS.Extend(Context, Alias, IdentifierLoc, CCLoc);
       return false;
     }
 
@@ -681,6 +681,7 @@ bool Sema::ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
   switch (Qualifier->getKind()) {
   case NestedNameSpecifier::Global:
   case NestedNameSpecifier::Namespace:
+  case NestedNameSpecifier::NamespaceAlias:
     // These are always namespace scopes.  We never want to enter a
     // namespace scope from anything but a file context.
     return CurContext->getRedeclContext()->isFileContext();
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index ab6dde5eb1..d75a1f1503 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -2868,6 +2868,7 @@ bool UnnamedLocalNoLinkageFinder::VisitNestedNameSpecifier(
   switch (NNS->getKind()) {
   case NestedNameSpecifier::Identifier:
   case NestedNameSpecifier::Namespace:
+  case NestedNameSpecifier::NamespaceAlias:
   case NestedNameSpecifier::Global:
     return false;
 
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index d30ed74310..ba80076003 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -1895,6 +1895,7 @@ TypeSourceInfo *Sema::GetTypeForDeclarator(Declarator &D, Scope *S,
           break;
 
         case NestedNameSpecifier::Namespace:
+        case NestedNameSpecifier::NamespaceAlias:
         case NestedNameSpecifier::Global:
           llvm_unreachable("Nested-name-specifier must name a type");
           break;
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 7a0754fc88..1b2822ead7 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -877,6 +877,16 @@ public:
                                                   NamespaceDecl *NS);
 
   /// \brief Build a new nested-name-specifier given the prefix and the
+  /// namespace alias named in the next step in the nested-name-specifier.
+  ///
+  /// By default, performs semantic analysis when building the new
+  /// nested-name-specifier. Subclasses may override this routine to provide
+  /// different behavior.
+  NestedNameSpecifier *RebuildNestedNameSpecifier(NestedNameSpecifier *Prefix,
+                                                  SourceRange Range,
+                                                  NamespaceAliasDecl *Alias);
+
+  /// \brief Build a new nested-name-specifier given the prefix and the
   /// type named in the next step in the nested-name-specifier.
   ///
   /// By default, performs semantic analysis when building the new
@@ -2450,6 +2460,19 @@ TreeTransform<Derived>::TransformNestedNameSpecifier(NestedNameSpecifier *NNS,
     return getDerived().RebuildNestedNameSpecifier(Prefix, Range, NS);
   }
 
+  case NestedNameSpecifier::NamespaceAlias: {
+    NamespaceAliasDecl *Alias
+      = cast_or_null<NamespaceAliasDecl>(
+                                    getDerived().TransformDecl(Range.getBegin(),
+                                                    NNS->getAsNamespaceAlias()));
+    if (!getDerived().AlwaysRebuild() &&
+        Prefix == NNS->getPrefix() &&
+        Alias == NNS->getAsNamespaceAlias())
+      return NNS;
+
+    return getDerived().RebuildNestedNameSpecifier(Prefix, Range, Alias);
+  }
+
   case NestedNameSpecifier::Global:
     // There is no meaningful transformation that one could perform on the
     // global scope.
@@ -7571,6 +7594,14 @@ template<typename Derived>
 NestedNameSpecifier *
 TreeTransform<Derived>::RebuildNestedNameSpecifier(NestedNameSpecifier *Prefix,
                                                    SourceRange Range,
+                                                   NamespaceAliasDecl *Alias) {
+  return NestedNameSpecifier::Create(SemaRef.Context, Prefix, Alias);
+}
+
+template<typename Derived>
+NestedNameSpecifier *
+TreeTransform<Derived>::RebuildNestedNameSpecifier(NestedNameSpecifier *Prefix,
+                                                   SourceRange Range,
                                                    bool TemplateKW,
                                                    QualType T) {
   if (T->isDependentType() || T->isRecordType() ||