C++ doesn't really use "namespaces" for different kinds of names the same

way that C does.  Among other differences, elaborated type specifiers
are defined to skip "non-types", which, as you might imagine, does not
include typedefs.  Rework our use of IDNS masks to capture the semantics
of different kinds of declarations better, and remove most current lookup
filters.  Removing the last remaining filter is more complicated and will
happen in a separate patch.

Fixes PR 6885 as well some spectrum of unfiled bugs.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@102164 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 32 deletions

diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 8de0c40fb7..445d08e666 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -202,26 +202,6 @@ static bool IsAcceptableOperatorName(NamedDecl *D, unsigned IDNS) {
     !D->getDeclContext()->isRecord();
 }
 
-static bool IsAcceptableNestedNameSpecifierName(NamedDecl *D, unsigned IDNS) {
-  // This lookup ignores everything that isn't a type.
-
-  // This is a fast check for the far most common case.
-  if (D->isInIdentifierNamespace(Decl::IDNS_Tag))
-    return true;
-
-  if (isa<UsingShadowDecl>(D))
-    D = cast<UsingShadowDecl>(D)->getTargetDecl();
-
-  return isa<TypeDecl>(D);
-}
-
-static bool IsAcceptableNamespaceName(NamedDecl *D, unsigned IDNS) {
-  // We don't need to look through using decls here because
-  // using decls aren't allowed to name namespaces.
-
-  return isa<NamespaceDecl>(D) || isa<NamespaceAliasDecl>(D);
-}
-
 /// Gets the default result filter for the given lookup.
 static inline
 LookupResult::ResultFilter getResultFilter(Sema::LookupNameKind NameKind) {
@@ -232,16 +212,12 @@ LookupResult::ResultFilter getResultFilter(Sema::LookupNameKind NameKind) {
   case Sema::LookupRedeclarationWithLinkage: // FIXME: check linkage, scoping
   case Sema::LookupUsingDeclName:
   case Sema::LookupObjCProtocolName:
+  case Sema::LookupNestedNameSpecifierName:
+  case Sema::LookupNamespaceName:
     return &IsAcceptableIDNS;
 
   case Sema::LookupOperatorName:
     return &IsAcceptableOperatorName;
-
-  case Sema::LookupNestedNameSpecifierName:
-    return &IsAcceptableNestedNameSpecifierName;
-
-  case Sema::LookupNamespaceName:
-    return &IsAcceptableNamespaceName;
   }
 
   llvm_unreachable("unkknown lookup kind");
@@ -260,15 +236,25 @@ static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
   case Sema::LookupRedeclarationWithLinkage:
     IDNS = Decl::IDNS_Ordinary;
     if (CPlusPlus) {
-      IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member;
+      IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member | Decl::IDNS_Namespace;
       if (Redeclaration) IDNS |= Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend;
     }
     break;
 
   case Sema::LookupTagName:
-    IDNS = Decl::IDNS_Tag;
-    if (CPlusPlus && Redeclaration)
-      IDNS |= Decl::IDNS_TagFriend;
+    if (CPlusPlus) {
+      IDNS = Decl::IDNS_Type;
+
+      // When looking for a redeclaration of a tag name, we add:
+      // 1) TagFriend to find undeclared friend decls
+      // 2) Namespace because they can't "overload" with tag decls.
+      // 3) Tag because it includes class templates, which can't
+      //    "overload" with tag decls.
+      if (Redeclaration)
+        IDNS |= Decl::IDNS_Tag | Decl::IDNS_TagFriend | Decl::IDNS_Namespace;
+    } else {
+      IDNS = Decl::IDNS_Tag;
+    }
     break;
 
   case Sema::LookupMemberName:
@@ -278,8 +264,11 @@ static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
     break;
 
   case Sema::LookupNestedNameSpecifierName:
+    IDNS = Decl::IDNS_Type | Decl::IDNS_Namespace;
+    break;
+
   case Sema::LookupNamespaceName:
-    IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member;
+    IDNS = Decl::IDNS_Namespace;
     break;
 
   case Sema::LookupUsingDeclName:
@@ -2134,7 +2123,8 @@ NamedDecl *VisibleDeclsRecord::checkHidden(NamedDecl *ND) {
                                IEnd = Pos->second.end();
          I != IEnd; ++I) {
       // A tag declaration does not hide a non-tag declaration.
-      if ((*I)->getIdentifierNamespace() == Decl::IDNS_Tag &&
+      if ((*I)->getIdentifierNamespace()
+            == (Decl::IDNS_Tag|Decl::IDNS_Type) &&
           (IDNS & (Decl::IDNS_Member | Decl::IDNS_Ordinary | 
                    Decl::IDNS_ObjCProtocol)))
         continue;