Implement DR 373 "Lookup on namespace qualified name in using-directive"

Summary:
3.4.6 [basic.lookup.udir] paragraph 1:
In a using-directive or namespace-alias-definition, during the lookup for a namespace-name or for a name in a nested-name-specifier, only namespace names are considered.

Reviewers: rsmith, aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D30848

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@298126 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 33 insertions, 8 deletions

diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index 618c8ab2ea..87facc449f 100644
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -266,15 +266,26 @@ Decl *Parser::ParseNamespaceAlias(SourceLocation NamespaceLoc,
 
   CXXScopeSpec SS;
   // Parse (optional) nested-name-specifier.
-  ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false);
+  ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false,
+                                 /*MayBePseudoDestructor=*/nullptr,
+                                 /*IsTypename=*/false,
+                                 /*LastII=*/nullptr,
+                                 /*OnlyNamespace=*/true);
 
-  if (SS.isInvalid() || Tok.isNot(tok::identifier)) {
+  if (Tok.isNot(tok::identifier)) {
     Diag(Tok, diag::err_expected_namespace_name);
     // Skip to end of the definition and eat the ';'.
     SkipUntil(tok::semi);
     return nullptr;
   }
 
+  if (SS.isInvalid()) {
+    // Diagnostics have been emitted in ParseOptionalCXXScopeSpecifier.
+    // Skip to end of the definition and eat the ';'.
+    SkipUntil(tok::semi);
+    return nullptr;
+  }
+
   // Parse identifier.
   IdentifierInfo *Ident = Tok.getIdentifierInfo();
   SourceLocation IdentLoc = ConsumeToken();
@@ -487,13 +498,17 @@ Decl *Parser::ParseUsingDirective(unsigned Context,
 
   CXXScopeSpec SS;
   // Parse (optional) nested-name-specifier.
-  ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false);
+  ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext=*/false,
+                                 /*MayBePseudoDestructor=*/nullptr,
+                                 /*IsTypename=*/false,
+                                 /*LastII=*/nullptr,
+                                 /*OnlyNamespace=*/true);
 
   IdentifierInfo *NamespcName = nullptr;
   SourceLocation IdentLoc = SourceLocation();
 
   // Parse namespace-name.
-  if (SS.isInvalid() || Tok.isNot(tok::identifier)) {
+  if (Tok.isNot(tok::identifier)) {
     Diag(Tok, diag::err_expected_namespace_name);
     // If there was invalid namespace name, skip to end of decl, and eat ';'.
     SkipUntil(tok::semi);
@@ -501,6 +516,13 @@ Decl *Parser::ParseUsingDirective(unsigned Context,
     return nullptr;
   }
 
+  if (SS.isInvalid()) {
+    // Diagnostics have been emitted in ParseOptionalCXXScopeSpecifier.
+    // Skip to end of the definition and eat the ';'.
+    SkipUntil(tok::semi);
+    return nullptr;
+  }
+
   // Parse identifier.
   NamespcName = Tok.getIdentifierInfo();
   IdentLoc = ConsumeToken();
diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index cb56ebb104..10339fc96b 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -141,13 +141,16 @@ void Parser::CheckForTemplateAndDigraph(Token &Next, ParsedType ObjectType,
 /// filled in with the leading identifier in the last component of the
 /// nested-name-specifier, if any.
 ///
+/// \param OnlyNamespace If true, only considers namespaces in lookup.
+///
 /// \returns true if there was an error parsing a scope specifier
 bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
                                             ParsedType ObjectType,
                                             bool EnteringContext,
                                             bool *MayBePseudoDestructor,
                                             bool IsTypename,
-                                            IdentifierInfo **LastII) {
+                                            IdentifierInfo **LastII,
+                                            bool OnlyNamespace) {
   assert(getLangOpts().CPlusPlus &&
          "Call sites of this function should be guarded by checking for C++");
 
@@ -450,9 +453,9 @@ bool Parser::ParseOptionalCXXScopeSpecifier(CXXScopeSpec &SS,
 
       bool IsCorrectedToColon = false;
       bool *CorrectionFlagPtr = ColonIsSacred ? &IsCorrectedToColon : nullptr;
-      if (Actions.ActOnCXXNestedNameSpecifier(getCurScope(), IdInfo,
-                                              EnteringContext, SS,
-                                              false, CorrectionFlagPtr)) {
+      if (Actions.ActOnCXXNestedNameSpecifier(
+              getCurScope(), IdInfo, EnteringContext, SS, false,
+              CorrectionFlagPtr, OnlyNamespace)) {
         // Identifier is not recognized as a nested name, but we can have
         // mistyped '::' instead of ':'.
         if (CorrectionFlagPtr && IsCorrectedToColon) {