Wire up redeclaration chains for Objective-C protocols, so that both

forward declarations and definitions of an Objective-C protocol are
represented within a single chain of ObjCProtocolDecls.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147412 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 65 insertions, 55 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index c8292b930e..a1ccf946d6 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1540,36 +1540,37 @@ DeclHasAttr(const Decl *D, const Attr *A) {
 }
 
 /// mergeDeclAttributes - Copy attributes from the Old decl to the New one.
-static void mergeDeclAttributes(Decl *newDecl, const Decl *oldDecl,
-                                ASTContext &C, bool mergeDeprecation = true) {
-  if (!oldDecl->hasAttrs())
+void Sema::mergeDeclAttributes(Decl *New, Decl *Old,
+                               bool MergeDeprecation) {
+  if (!Old->hasAttrs())
     return;
 
-  bool foundAny = newDecl->hasAttrs();
+  bool foundAny = New->hasAttrs();
 
   // Ensure that any moving of objects within the allocated map is done before
   // we process them.
-  if (!foundAny) newDecl->setAttrs(AttrVec());
+  if (!foundAny) New->setAttrs(AttrVec());
 
   for (specific_attr_iterator<InheritableAttr>
-       i = oldDecl->specific_attr_begin<InheritableAttr>(),
-       e = oldDecl->specific_attr_end<InheritableAttr>(); i != e; ++i) {
+         i = Old->specific_attr_begin<InheritableAttr>(),
+         e = Old->specific_attr_end<InheritableAttr>(); 
+       i != e; ++i) {
     // Ignore deprecated/unavailable/availability attributes if requested.
-    if (!mergeDeprecation &&
+    if (!MergeDeprecation &&
         (isa<DeprecatedAttr>(*i) || 
          isa<UnavailableAttr>(*i) ||
          isa<AvailabilityAttr>(*i)))
       continue;
 
-    if (!DeclHasAttr(newDecl, *i)) {
-      InheritableAttr *newAttr = cast<InheritableAttr>((*i)->clone(C));
+    if (!DeclHasAttr(New, *i)) {
+      InheritableAttr *newAttr = cast<InheritableAttr>((*i)->clone(Context));
       newAttr->setInherited(true);
-      newDecl->addAttr(newAttr);
+      New->addAttr(newAttr);
       foundAny = true;
     }
   }
 
-  if (!foundAny) newDecl->dropAttrs();
+  if (!foundAny) New->dropAttrs();
 }
 
 /// mergeParamDeclAttributes - Copy attributes from the old parameter
@@ -2035,7 +2036,7 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, Decl *OldD) {
 /// \returns false
 bool Sema::MergeCompatibleFunctionDecls(FunctionDecl *New, FunctionDecl *Old) {
   // Merge the attributes
-  mergeDeclAttributes(New, Old, Context);
+  mergeDeclAttributes(New, Old);
 
   // Merge the storage class.
   if (Old->getStorageClass() != SC_Extern &&
@@ -2061,13 +2062,13 @@ bool Sema::MergeCompatibleFunctionDecls(FunctionDecl *New, FunctionDecl *Old) {
 
 
 void Sema::mergeObjCMethodDecls(ObjCMethodDecl *newMethod,
-                                const ObjCMethodDecl *oldMethod) {
+                                ObjCMethodDecl *oldMethod) {
   // We don't want to merge unavailable and deprecated attributes
   // except from interface to implementation.
   bool mergeDeprecation = isa<ObjCImplDecl>(newMethod->getDeclContext());
 
   // Merge the attributes.
-  mergeDeclAttributes(newMethod, oldMethod, Context, mergeDeprecation);
+  mergeDeclAttributes(newMethod, oldMethod, mergeDeprecation);
 
   // Merge attributes from the parameters.
   ObjCMethodDecl::param_const_iterator oi = oldMethod->param_begin();
@@ -2174,7 +2175,7 @@ void Sema::MergeVarDecl(VarDecl *New, LookupResult &Previous) {
     New->setInvalidDecl();
   }
   
-  mergeDeclAttributes(New, Old, Context);
+  mergeDeclAttributes(New, Old);
   // Warn if an already-declared variable is made a weak_import in a subsequent 
   // declaration
   if (New->getAttr<WeakImportAttr>() &&
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index eb178612c8..c4261ecbb8 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -569,46 +569,50 @@ Sema::ActOnStartProtocolInterface(SourceLocation AtProtoInterfaceLoc,
   bool err = false;
   // FIXME: Deal with AttrList.
   assert(ProtocolName && "Missing protocol identifier");
-  ObjCProtocolDecl *PDecl = LookupProtocol(ProtocolName, ProtocolLoc);
-  if (PDecl) {
-    // Protocol already seen. Better be a forward protocol declaration
-    if (ObjCProtocolDecl *Def = PDecl->getDefinition()) {
-      Diag(ProtocolLoc, diag::warn_duplicate_protocol_def) << ProtocolName;
-      Diag(Def->getLocation(), diag::note_previous_definition);
-
-      // Create a new protocol that is completely distinct from previous
-      // declarations, and do not make this protocol available for name lookup.
-      // That way, we'll end up completely ignoring the duplicate.
-      // FIXME: Can we turn this into an error?
-      PDecl = ObjCProtocolDecl::Create(Context, CurContext, ProtocolName,
-                                       ProtocolLoc, AtProtoInterfaceLoc,
-                                       /*isForwardDecl=*/false);
-      PDecl->startDefinition();
-    } else {
+  ObjCProtocolDecl *PrevDecl = LookupProtocol(ProtocolName, ProtocolLoc,
+                                              ForRedeclaration);
+  ObjCProtocolDecl *PDecl = 0;
+  if (ObjCProtocolDecl *Def = PrevDecl? PrevDecl->getDefinition() : 0) {
+    // If we already have a definition, complain.
+    Diag(ProtocolLoc, diag::warn_duplicate_protocol_def) << ProtocolName;
+    Diag(Def->getLocation(), diag::note_previous_definition);
+
+    // Create a new protocol that is completely distinct from previous
+    // declarations, and do not make this protocol available for name lookup.
+    // That way, we'll end up completely ignoring the duplicate.
+    // FIXME: Can we turn this into an error?
+    PDecl = ObjCProtocolDecl::Create(Context, CurContext, ProtocolName,
+                                     ProtocolLoc, AtProtoInterfaceLoc,
+                                     /*PrevDecl=*/0,
+                                     /*isForwardDecl=*/false);
+    PDecl->startDefinition();
+  } else {
+    if (PrevDecl) {
+      // Check for circular dependencies among protocol declarations. This can
+      // only happen if this protocol was forward-declared.
       ObjCList<ObjCProtocolDecl> PList;
       PList.set((ObjCProtocolDecl *const*)ProtoRefs, NumProtoRefs, Context);
       err = CheckForwardProtocolDeclarationForCircularDependency(
-              ProtocolName, ProtocolLoc, PDecl->getLocation(), PList);
-  
-      // Make sure the cached decl gets a valid start location.
-      PDecl->setAtStartLoc(AtProtoInterfaceLoc);
-      PDecl->setLocation(ProtocolLoc);
-      // Since this ObjCProtocolDecl was created by a forward declaration,
-      // we now add it to the DeclContext since it wasn't added before
-      PDecl->setLexicalDeclContext(CurContext);
-      CurContext->addDecl(PDecl);
-      PDecl->completedForwardDecl();
+              ProtocolName, ProtocolLoc, PrevDecl->getLocation(), PList);
     }
-  } else {
+
+    // Create the new declaration.
     PDecl = ObjCProtocolDecl::Create(Context, CurContext, ProtocolName,
                                      ProtocolLoc, AtProtoInterfaceLoc,
+                                     /*PrevDecl=*/PrevDecl, 
                                      /*isForwardDecl=*/false);
+    
     PushOnScopeChains(PDecl, TUScope);
     PDecl->startDefinition();
   }
   
   if (AttrList)
     ProcessDeclAttributeList(TUScope, PDecl, AttrList);
+  
+  // Merge attributes from previous declarations.
+  if (PrevDecl)
+    mergeDeclAttributes(PDecl, PrevDecl);
+
   if (!err && NumProtoRefs ) {
     /// Check then save referenced protocols.
     PDecl->setProtocolList((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs,
@@ -700,22 +704,26 @@ Sema::ActOnForwardProtocolDeclaration(SourceLocation AtProtocolLoc,
 
   for (unsigned i = 0; i != NumElts; ++i) {
     IdentifierInfo *Ident = IdentList[i].first;
-    ObjCProtocolDecl *PDecl = LookupProtocol(Ident, IdentList[i].second);
-    bool isNew = false;
-    if (PDecl == 0) { // Not already seen?
-      PDecl = ObjCProtocolDecl::Create(Context, CurContext, Ident,
-                                       IdentList[i].second, AtProtocolLoc,
-                                       /*isForwardDecl=*/true);
-      PushOnScopeChains(PDecl, TUScope, false);
-      isNew = true;
-    }
+    ObjCProtocolDecl *PrevDecl = LookupProtocol(Ident, IdentList[i].second,
+                                                ForRedeclaration);
+    ObjCProtocolDecl *PDecl
+      = ObjCProtocolDecl::Create(Context, CurContext, Ident, 
+                                 IdentList[i].second, AtProtocolLoc,
+                                 PrevDecl, /*isForwardDecl=*/true);
+        
+    PushOnScopeChains(PDecl, TUScope);
+    
     if (attrList) {
       ProcessDeclAttributeList(TUScope, PDecl, attrList);
-      if (!isNew) {
+      if (PrevDecl) {
         if (ASTMutationListener *L = Context.getASTMutationListener())
           L->UpdatedAttributeList(PDecl);
       }
     }
+    
+    if (PrevDecl)
+      mergeDeclAttributes(PDecl, PrevDecl);
+
     Protocols.push_back(PDecl);
     ProtoLocs.push_back(IdentList[i].second);
   }
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index f7dd69a78a..63d14f46c1 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -2180,9 +2180,10 @@ NamedDecl *Sema::LookupSingleName(Scope *S, DeclarationName Name,
 
 /// \brief Find the protocol with the given name, if any.
 ObjCProtocolDecl *Sema::LookupProtocol(IdentifierInfo *II,
-                                       SourceLocation IdLoc) {
+                                       SourceLocation IdLoc,
+                                       RedeclarationKind Redecl) {
   Decl *D = LookupSingleName(TUScope, II, IdLoc,
-                             LookupObjCProtocolName);
+                             LookupObjCProtocolName, Redecl);
   return cast_or_null<ObjCProtocolDecl>(D);
 }