From: Douglas Gregor <dgregor@apple.com>
Date: Wed, 4 Jan 2012 16:44:10 +0000 (+0000)
Subject: Implement declaration merging for typedefs loaded from disjoint
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=da795b45f47df61a1b5a491e8d4ea078cf2a217b;p=clang

Implement declaration merging for typedefs loaded from disjoint
modules, so long as the typedefs refer to the same underlying
type. This ensures that the typedefs end up in the same redeclaration
chain.

To test this, fix name lookup for C/Objective-C to properly deal with
multiple declarations with the same name in the same scope.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147533 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 48ae1b970d..ae950ff27a 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -1179,29 +1179,28 @@ bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation) {
 
         // Check whether there are any other declarations with the same name
         // and in the same scope.
+        if (I != IEnd) {
+          DeclContext *DC = (*I)->getDeclContext()->getRedeclContext();
+          IdentifierResolver::iterator LastI = I;
+          for (++LastI; LastI != IEnd; ++LastI) {
+            DeclContext *LastDC 
+              = (*LastI)->getDeclContext()->getRedeclContext();
+            if (!(*LastI)->isInIdentifierNamespace(IDNS))
+              continue;
+            
+            if (!LastDC->Equals(DC))
+              break;
+            
+            if (!LastDC->isFileContext() && !S->isDeclScope(*LastI))
+              break;
+            
+            D = R.isForRedeclaration()? *LastI : getVisibleDecl(*LastI);
+            if (D)
+              R.addDecl(D);
+          }
 
-        // Figure out what scope the identifier is in.
-        while (S->getParent() &&
-               (!(S->getFlags() & Scope::DeclScope) ||
-                !S->isDeclScope(*I)))
-          S = S->getParent();
-
-        // Find the last declaration in this scope (with the same
-        // name, naturally).
-        IdentifierResolver::iterator LastI = I;
-        for (++LastI; LastI != IEnd; ++LastI) {
-          if (!S->isDeclScope(*LastI))
-            break;
-          
-          if (!(*LastI)->isInIdentifierNamespace(IDNS))
-            continue;
-          
-          D = R.isForRedeclaration()? *LastI : getVisibleDecl(*LastI);
-          if (D)
-            R.addDecl(D);
+          R.resolveKind();
         }
-
-        R.resolveKind();
         return true;
       }
   } else {
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 4871a3049a..c00b69cf75 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -402,9 +402,14 @@ void ASTDeclReader::VisitTypeDecl(TypeDecl *TD) {
 }
 
 void ASTDeclReader::VisitTypedefNameDecl(TypedefNameDecl *TD) {
-  VisitRedeclarable(TD);
+  // Record the declaration -> global ID mapping.
+  Reader.DeclToID[TD] = ThisDeclID;
+  
+  RedeclarableResult Redecl = VisitRedeclarable(TD);
   VisitTypeDecl(TD);
-  TD->setTypeSourceInfo(GetTypeSourceInfo(Record, Idx));  
+  
+  TD->setTypeSourceInfo(GetTypeSourceInfo(Record, Idx));
+  mergeRedeclarable(TD, Redecl);
 }
 
 void ASTDeclReader::VisitTypedefDecl(TypedefDecl *TD) {
@@ -1668,15 +1673,22 @@ static bool isSameEntity(NamedDecl *X, NamedDecl *Y) {
   if (X == Y)
     return true;
   
-  // Must have the same kind.
-  if (X->getKind() != Y->getKind())
-    return false;
-  
   // Must be in the same context.
   if (!X->getDeclContext()->getRedeclContext()->Equals(
          Y->getDeclContext()->getRedeclContext()))
     return false;
+
+  // Two typedefs refer to the same entity if they have the same underlying
+  // type.
+  if (TypedefNameDecl *TypedefX = dyn_cast<TypedefNameDecl>(X))
+    if (TypedefNameDecl *TypedefY = dyn_cast<TypedefNameDecl>(Y))
+      return X->getASTContext().hasSameType(TypedefX->getUnderlyingType(),
+                                            TypedefY->getUnderlyingType());
   
+  // Must have the same kind.
+  if (X->getKind() != Y->getKind())
+    return false;
+    
   // Objective-C classes and protocols with the same name always match.
   if (isa<ObjCInterfaceDecl>(X) || isa<ObjCProtocolDecl>(X))
     return true;