SemaDeclObjC.cpp

//===--- SemaDeclObjC.cpp - Semantic Analysis for ObjC Declarations -------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements semantic analysis for Objective C declarations.
//
//===----------------------------------------------------------------------===//

#include "Sema.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Parse/DeclSpec.h"
using namespace clang;

/// ActOnStartOfObjCMethodDef - This routine sets up parameters; invisible
/// and user declared, in the method definition's AST.
void Sema::ActOnStartOfObjCMethodDef(Scope *FnBodyScope, DeclPtrTy D) {
  assert(getCurMethodDecl() == 0 && "Method parsing confused");
  ObjCMethodDecl *MDecl = dyn_cast_or_null<ObjCMethodDecl>(D.getAs<Decl>());
  
  // If we don't have a valid method decl, simply return.
  if (!MDecl)
    return;

  // Allow the rest of sema to find private method decl implementations.
  if (MDecl->isInstanceMethod())
    AddInstanceMethodToGlobalPool(MDecl);
  else
    AddFactoryMethodToGlobalPool(MDecl);
  
  // Allow all of Sema to see that we are entering a method definition.
  PushDeclContext(FnBodyScope, MDecl);

  // Create Decl objects for each parameter, entrring them in the scope for
  // binding to their use.

  // Insert the invisible arguments, self and _cmd!
  MDecl->createImplicitParams(Context, MDecl->getClassInterface());
  
  PushOnScopeChains(MDecl->getSelfDecl(), FnBodyScope);
  PushOnScopeChains(MDecl->getCmdDecl(), FnBodyScope);

  // Introduce all of the other parameters into this scope.
  for (ObjCMethodDecl::param_iterator PI = MDecl->param_begin(),
       E = MDecl->param_end(); PI != E; ++PI)
    if ((*PI)->getIdentifier())
      PushOnScopeChains(*PI, FnBodyScope);
}

Sema::DeclPtrTy Sema::
ActOnStartClassInterface(SourceLocation AtInterfaceLoc,
                         IdentifierInfo *ClassName, SourceLocation ClassLoc,
                         IdentifierInfo *SuperName, SourceLocation SuperLoc,
                         const DeclPtrTy *ProtoRefs, unsigned NumProtoRefs,
                         SourceLocation EndProtoLoc, AttributeList *AttrList) {
  assert(ClassName && "Missing class identifier");
  
  // Check for another declaration kind with the same name.
  NamedDecl *PrevDecl = LookupName(TUScope, ClassName, LookupOrdinaryName);
  if (PrevDecl && PrevDecl->isTemplateParameter()) {
    // Maybe we will complain about the shadowed template parameter.
    DiagnoseTemplateParameterShadow(ClassLoc, PrevDecl);
    // Just pretend that we didn't see the previous declaration.
    PrevDecl = 0;
  }

  if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
    Diag(ClassLoc, diag::err_redefinition_different_kind) << ClassName;
    Diag(PrevDecl->getLocation(), diag::note_previous_definition);
  }
  
  ObjCInterfaceDecl* IDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);
  if (IDecl) {
    // Class already seen. Is it a forward declaration?
    if (!IDecl->isForwardDecl()) {
      IDecl->setInvalidDecl();
      Diag(AtInterfaceLoc, diag::err_duplicate_class_def)<<IDecl->getDeclName();
      Diag(IDecl->getLocation(), diag::note_previous_definition);

      // Return the previous class interface.
      // FIXME: don't leak the objects passed in!
      return DeclPtrTy::make(IDecl);
    } else {
      IDecl->setLocation(AtInterfaceLoc);
      IDecl->setForwardDecl(false);
    }
  } else {
    IDecl = ObjCInterfaceDecl::Create(Context, CurContext, AtInterfaceLoc, 
                                      ClassName, ClassLoc);
    if (AttrList)
      ProcessDeclAttributeList(IDecl, AttrList);
  
    ObjCInterfaceDecls[ClassName] = IDecl;
    // FIXME: PushOnScopeChains
    CurContext->addDecl(Context, IDecl);
    // Remember that this needs to be removed when the scope is popped.
    TUScope->AddDecl(DeclPtrTy::make(IDecl));
  }
  
  if (SuperName) {
    // Check if a different kind of symbol declared in this scope.
    PrevDecl = LookupName(TUScope, SuperName, LookupOrdinaryName);

    ObjCInterfaceDecl *SuperClassDecl = 
                                  dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);

    // Diagnose classes that inherit from deprecated classes.
    if (SuperClassDecl)
      (void)DiagnoseUseOfDecl(SuperClassDecl, SuperLoc);
    
    if (PrevDecl && SuperClassDecl == 0) {
      // The previous declaration was not a class decl. Check if we have a
      // typedef. If we do, get the underlying class type.
      if (const TypedefDecl *TDecl = dyn_cast_or_null<TypedefDecl>(PrevDecl)) {
        QualType T = TDecl->getUnderlyingType();
        if (T->isObjCInterfaceType()) {
          if (NamedDecl *IDecl = T->getAsObjCInterfaceType()->getDecl())
            SuperClassDecl = dyn_cast<ObjCInterfaceDecl>(IDecl);
        }
      }
      
      // This handles the following case:
      //
      // typedef int SuperClass;
      // @interface MyClass : SuperClass {} @end
      //
      if (!SuperClassDecl) {
        Diag(SuperLoc, diag::err_redefinition_different_kind) << SuperName;
        Diag(PrevDecl->getLocation(), diag::note_previous_definition);
      }
    }
    
    if (!dyn_cast_or_null<TypedefDecl>(PrevDecl)) {
      if (!SuperClassDecl)
        Diag(SuperLoc, diag::err_undef_superclass)
          << SuperName << ClassName << SourceRange(AtInterfaceLoc, ClassLoc);
      else if (SuperClassDecl->isForwardDecl())
        Diag(SuperLoc, diag::err_undef_superclass)
          << SuperClassDecl->getDeclName() << ClassName
          << SourceRange(AtInterfaceLoc, ClassLoc);
    }
    IDecl->setSuperClass(SuperClassDecl);
    IDecl->setSuperClassLoc(SuperLoc);
    IDecl->setLocEnd(SuperLoc);
  } else { // we have a root class.
    IDecl->setLocEnd(ClassLoc);
  }
  
  /// Check then save referenced protocols.
  if (NumProtoRefs) {
    IDecl->setProtocolList((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs,
                           Context);
    IDecl->setLocEnd(EndProtoLoc);
  }
  
  CheckObjCDeclScope(IDecl);
  return DeclPtrTy::make(IDecl);
}

/// ActOnCompatiblityAlias - this action is called after complete parsing of
/// @compatibility_alias declaration. It sets up the alias relationships.
Sema::DeclPtrTy Sema::ActOnCompatiblityAlias(SourceLocation AtLoc,
                                             IdentifierInfo *AliasName, 
                                             SourceLocation AliasLocation,
                                             IdentifierInfo *ClassName,
                                             SourceLocation ClassLocation) {
  // Look for previous declaration of alias name
  NamedDecl *ADecl = LookupName(TUScope, AliasName, LookupOrdinaryName);
  if (ADecl) {
    if (isa<ObjCCompatibleAliasDecl>(ADecl))
      Diag(AliasLocation, diag::warn_previous_alias_decl);
    else
      Diag(AliasLocation, diag::err_conflicting_aliasing_type) << AliasName;
    Diag(ADecl->getLocation(), diag::note_previous_declaration);
    return DeclPtrTy();
  }
  // Check for class declaration
  NamedDecl *CDeclU = LookupName(TUScope, ClassName, LookupOrdinaryName);
  if (const TypedefDecl *TDecl = dyn_cast_or_null<TypedefDecl>(CDeclU)) {
    QualType T = TDecl->getUnderlyingType();
    if (T->isObjCInterfaceType()) {
      if (NamedDecl *IDecl = T->getAsObjCInterfaceType()->getDecl()) {
        ClassName = IDecl->getIdentifier();
        CDeclU = LookupName(TUScope, ClassName, LookupOrdinaryName);
      }
    }
  }
  ObjCInterfaceDecl *CDecl = dyn_cast_or_null<ObjCInterfaceDecl>(CDeclU);
  if (CDecl == 0) {
    Diag(ClassLocation, diag::warn_undef_interface) << ClassName;
    if (CDeclU)
      Diag(CDeclU->getLocation(), diag::note_previous_declaration);
    return DeclPtrTy();
  }
  
  // Everything checked out, instantiate a new alias declaration AST.
  ObjCCompatibleAliasDecl *AliasDecl = 
    ObjCCompatibleAliasDecl::Create(Context, CurContext, AtLoc, AliasName, CDecl);
  
  ObjCAliasDecls[AliasName] = AliasDecl;

  // FIXME: PushOnScopeChains?
  CurContext->addDecl(Context, AliasDecl);
  if (!CheckObjCDeclScope(AliasDecl))
    TUScope->AddDecl(DeclPtrTy::make(AliasDecl));

  return DeclPtrTy::make(AliasDecl);
}

void Sema::CheckForwardProtocolDeclarationForCircularDependency(
  IdentifierInfo *PName,
  SourceLocation &Ploc, SourceLocation PrevLoc,
  const ObjCList<ObjCProtocolDecl> &PList) 
{
  for (ObjCList<ObjCProtocolDecl>::iterator I = PList.begin(),
       E = PList.end(); I != E; ++I) {
       
    if (ObjCProtocolDecl *PDecl = ObjCProtocols[(*I)->getIdentifier()]) {
      if (PDecl->getIdentifier() == PName) {
        Diag(Ploc, diag::err_protocol_has_circular_dependency);
        Diag(PrevLoc, diag::note_previous_definition);
      }
      CheckForwardProtocolDeclarationForCircularDependency(PName, Ploc, 
        PDecl->getLocation(), PDecl->getReferencedProtocols());
    }
  }
}

Sema::DeclPtrTy
Sema::ActOnStartProtocolInterface(SourceLocation AtProtoInterfaceLoc,
                                  IdentifierInfo *ProtocolName,
                                  SourceLocation ProtocolLoc,
                                  const DeclPtrTy *ProtoRefs,
                                  unsigned NumProtoRefs,
                                  SourceLocation EndProtoLoc,
                                  AttributeList *AttrList) {
  // FIXME: Deal with AttrList.
  assert(ProtocolName && "Missing protocol identifier");
  ObjCProtocolDecl *PDecl = ObjCProtocols[ProtocolName];
  if (PDecl) {
    // Protocol already seen. Better be a forward protocol declaration
    if (!PDecl->isForwardDecl()) {
      Diag(ProtocolLoc, diag::warn_duplicate_protocol_def) << ProtocolName;
      Diag(PDecl->getLocation(), diag::note_previous_definition);
      // Just return the protocol we already had.
      // FIXME: don't leak the objects passed in!
      return DeclPtrTy::make(PDecl);
    }
    ObjCList<ObjCProtocolDecl> PList;
    PList.set((ObjCProtocolDecl *const*)ProtoRefs, NumProtoRefs, Context); 
    CheckForwardProtocolDeclarationForCircularDependency(
      ProtocolName, ProtocolLoc, PDecl->getLocation(), PList);
    PList.Destroy(Context);
    
    // Make sure the cached decl gets a valid start location.
    PDecl->setLocation(AtProtoInterfaceLoc);
    PDecl->setForwardDecl(false);
  } else {
    PDecl = ObjCProtocolDecl::Create(Context, CurContext, 
                                     AtProtoInterfaceLoc,ProtocolName);
    // FIXME: PushOnScopeChains?
    CurContext->addDecl(Context, PDecl);
    PDecl->setForwardDecl(false);
    ObjCProtocols[ProtocolName] = PDecl;
  }
  if (AttrList)
    ProcessDeclAttributeList(PDecl, AttrList);
  if (NumProtoRefs) {
    /// Check then save referenced protocols.
    PDecl->setProtocolList((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs,Context);
    PDecl->setLocEnd(EndProtoLoc);
  }
  
  CheckObjCDeclScope(PDecl);  
  return DeclPtrTy::make(PDecl);
}

/// FindProtocolDeclaration - This routine looks up protocols and
/// issues an error if they are not declared. It returns list of
/// protocol declarations in its 'Protocols' argument.
void
Sema::FindProtocolDeclaration(bool WarnOnDeclarations,
                              const IdentifierLocPair *ProtocolId,
                              unsigned NumProtocols,
                              llvm::SmallVectorImpl<DeclPtrTy> &Protocols) {
  for (unsigned i = 0; i != NumProtocols; ++i) {
    ObjCProtocolDecl *PDecl = ObjCProtocols[ProtocolId[i].first];
    if (!PDecl) {
      Diag(ProtocolId[i].second, diag::err_undeclared_protocol)
        << ProtocolId[i].first;
      continue;
    }
    
    (void)DiagnoseUseOfDecl(PDecl, ProtocolId[i].second);

    // If this is a forward declaration and we are supposed to warn in this
    // case, do it.
    if (WarnOnDeclarations && PDecl->isForwardDecl())
      Diag(ProtocolId[i].second, diag::warn_undef_protocolref)
        << ProtocolId[i].first;
    Protocols.push_back(DeclPtrTy::make(PDecl));
  }
}

/// DiagnosePropertyMismatch - Compares two properties for their
/// attributes and types and warns on a variety of inconsistencies.
///
void
Sema::DiagnosePropertyMismatch(ObjCPropertyDecl *Property, 
                               ObjCPropertyDecl *SuperProperty,
                               const IdentifierInfo *inheritedName) {
  ObjCPropertyDecl::PropertyAttributeKind CAttr = 
  Property->getPropertyAttributes();
  ObjCPropertyDecl::PropertyAttributeKind SAttr = 
  SuperProperty->getPropertyAttributes();
  if ((CAttr & ObjCPropertyDecl::OBJC_PR_readonly)
      && (SAttr & ObjCPropertyDecl::OBJC_PR_readwrite))
    Diag(Property->getLocation(), diag::warn_readonly_property)
      << Property->getDeclName() << inheritedName;
  if ((CAttr & ObjCPropertyDecl::OBJC_PR_copy)
      != (SAttr & ObjCPropertyDecl::OBJC_PR_copy))
    Diag(Property->getLocation(), diag::warn_property_attribute)
      << Property->getDeclName() << "copy" << inheritedName;
  else if ((CAttr & ObjCPropertyDecl::OBJC_PR_retain)
           != (SAttr & ObjCPropertyDecl::OBJC_PR_retain))
    Diag(Property->getLocation(), diag::warn_property_attribute)
      << Property->getDeclName() << "retain" << inheritedName;
  
  if ((CAttr & ObjCPropertyDecl::OBJC_PR_nonatomic)
      != (SAttr & ObjCPropertyDecl::OBJC_PR_nonatomic))
    Diag(Property->getLocation(), diag::warn_property_attribute)
      << Property->getDeclName() << "atomic" << inheritedName;
  if (Property->getSetterName() != SuperProperty->getSetterName())
    Diag(Property->getLocation(), diag::warn_property_attribute)
      << Property->getDeclName() << "setter" << inheritedName; 
  if (Property->getGetterName() != SuperProperty->getGetterName())
    Diag(Property->getLocation(), diag::warn_property_attribute)
      << Property->getDeclName() << "getter" << inheritedName;

  QualType LHSType = 
    Context.getCanonicalType(SuperProperty->getType());
  QualType RHSType = 
    Context.getCanonicalType(Property->getType());
    
  if (!Context.typesAreCompatible(LHSType, RHSType)) {
    // FIXME: Incorporate this test with typesAreCompatible.
    if (LHSType->isObjCQualifiedIdType() && RHSType->isObjCQualifiedIdType())
      if (ObjCQualifiedIdTypesAreCompatible(LHSType, RHSType, false))
        return;
    Diag(Property->getLocation(), diag::warn_property_types_are_incompatible)
      << Property->getType() << SuperProperty->getType() << inheritedName;
  }
}

/// ComparePropertiesInBaseAndSuper - This routine compares property
/// declarations in base and its super class, if any, and issues
/// diagnostics in a variety of inconsistant situations.
///
void Sema::ComparePropertiesInBaseAndSuper(ObjCInterfaceDecl *IDecl) {
  ObjCInterfaceDecl *SDecl = IDecl->getSuperClass();
  if (!SDecl)
    return;
  // FIXME: O(N^2)
  for (ObjCInterfaceDecl::prop_iterator S = SDecl->prop_begin(Context),
       E = SDecl->prop_end(Context); S != E; ++S) {
    ObjCPropertyDecl *SuperPDecl = (*S);
    // Does property in super class has declaration in current class?
    for (ObjCInterfaceDecl::prop_iterator I = IDecl->prop_begin(Context),
         E = IDecl->prop_end(Context); I != E; ++I) {
      ObjCPropertyDecl *PDecl = (*I);
      if (SuperPDecl->getIdentifier() == PDecl->getIdentifier())
          DiagnosePropertyMismatch(PDecl, SuperPDecl, 
                                   SDecl->getIdentifier());
    }
  }
}

/// MergeOneProtocolPropertiesIntoClass - This routine goes thru the list
/// of properties declared in a protocol and adds them to the list
/// of properties for current class/category if it is not there already.
void
Sema::MergeOneProtocolPropertiesIntoClass(Decl *CDecl,
                                          ObjCProtocolDecl *PDecl) {
  ObjCInterfaceDecl *IDecl = dyn_cast_or_null<ObjCInterfaceDecl>(CDecl);
  if (!IDecl) {
    // Category
    ObjCCategoryDecl *CatDecl = static_cast<ObjCCategoryDecl*>(CDecl);
    assert (CatDecl && "MergeOneProtocolPropertiesIntoClass");
    for (ObjCProtocolDecl::prop_iterator P = PDecl->prop_begin(Context),
         E = PDecl->prop_end(Context); P != E; ++P) {
      ObjCPropertyDecl *Pr = (*P);
      ObjCCategoryDecl::prop_iterator CP, CE;
      // Is this property already in  category's list of properties?
      for (CP = CatDecl->prop_begin(Context), CE = CatDecl->prop_end(Context); 
           CP != CE; ++CP)
        if ((*CP)->getIdentifier() == Pr->getIdentifier())
          break;
      if (CP != CE)
        // Property protocol already exist in class. Diagnose any mismatch.
        DiagnosePropertyMismatch((*CP), Pr, PDecl->getIdentifier());
    }
    return;
  }
  for (ObjCProtocolDecl::prop_iterator P = PDecl->prop_begin(Context),
       E = PDecl->prop_end(Context); P != E; ++P) {
    ObjCPropertyDecl *Pr = (*P);
    ObjCInterfaceDecl::prop_iterator CP, CE;
    // Is this property already in  class's list of properties?
    for (CP = IDecl->prop_begin(Context), CE = IDecl->prop_end(Context); 
         CP != CE; ++CP)
      if ((*CP)->getIdentifier() == Pr->getIdentifier())
        break;
    if (CP != CE)
      // Property protocol already exist in class. Diagnose any mismatch.
      DiagnosePropertyMismatch((*CP), Pr, PDecl->getIdentifier());
    }
}

/// MergeProtocolPropertiesIntoClass - This routine merges properties
/// declared in 'MergeItsProtocols' objects (which can be a class or an
/// inherited protocol into the list of properties for class/category 'CDecl'
///
void Sema::MergeProtocolPropertiesIntoClass(Decl *CDecl,
                                            DeclPtrTy MergeItsProtocols) {
  Decl *ClassDecl = MergeItsProtocols.getAs<Decl>();
  ObjCInterfaceDecl *IDecl = dyn_cast_or_null<ObjCInterfaceDecl>(CDecl);

  if (!IDecl) {
    // Category
    ObjCCategoryDecl *CatDecl = static_cast<ObjCCategoryDecl*>(CDecl);
    assert (CatDecl && "MergeProtocolPropertiesIntoClass");
    if (ObjCCategoryDecl *MDecl = dyn_cast<ObjCCategoryDecl>(ClassDecl)) {
      for (ObjCCategoryDecl::protocol_iterator P = MDecl->protocol_begin(),
           E = MDecl->protocol_end(); P != E; ++P)
      // Merge properties of category (*P) into IDECL's
      MergeOneProtocolPropertiesIntoClass(CatDecl, *P);
    
      // Go thru the list of protocols for this category and recursively merge
      // their properties into this class as well.
      for (ObjCCategoryDecl::protocol_iterator P = CatDecl->protocol_begin(),
           E = CatDecl->protocol_end(); P != E; ++P)
        MergeProtocolPropertiesIntoClass(CatDecl, DeclPtrTy::make(*P));
    } else {
      ObjCProtocolDecl *MD = cast<ObjCProtocolDecl>(ClassDecl);
      for (ObjCProtocolDecl::protocol_iterator P = MD->protocol_begin(),
           E = MD->protocol_end(); P != E; ++P)
        MergeOneProtocolPropertiesIntoClass(CatDecl, *P);
    }
    return;
  }

  if (ObjCInterfaceDecl *MDecl = dyn_cast<ObjCInterfaceDecl>(ClassDecl)) {
    for (ObjCInterfaceDecl::protocol_iterator P = MDecl->protocol_begin(),
         E = MDecl->protocol_end(); P != E; ++P)
      // Merge properties of class (*P) into IDECL's
      MergeOneProtocolPropertiesIntoClass(IDecl, *P);
    
    // Go thru the list of protocols for this class and recursively merge
    // their properties into this class as well.
    for (ObjCInterfaceDecl::protocol_iterator P = IDecl->protocol_begin(),
         E = IDecl->protocol_end(); P != E; ++P)
      MergeProtocolPropertiesIntoClass(IDecl, DeclPtrTy::make(*P));
  } else {
    ObjCProtocolDecl *MD = cast<ObjCProtocolDecl>(ClassDecl);
    for (ObjCProtocolDecl::protocol_iterator P = MD->protocol_begin(),
         E = MD->protocol_end(); P != E; ++P)
      MergeOneProtocolPropertiesIntoClass(IDecl, *P);
  }
}

/// DiagnoseClassExtensionDupMethods - Check for duplicate declaration of
/// a class method in its extension.
///
void Sema::DiagnoseClassExtensionDupMethods(ObjCCategoryDecl *CAT, 
                                            ObjCInterfaceDecl *ID) {
  if (!ID)
    return;  // Possibly due to previous error

  llvm::DenseMap<Selector, const ObjCMethodDecl*> MethodMap;
  for (ObjCInterfaceDecl::method_iterator i = ID->meth_begin(Context),
       e =  ID->meth_end(Context); i != e; ++i) {
    ObjCMethodDecl *MD = *i;
    MethodMap[MD->getSelector()] = MD;
  }

  if (MethodMap.empty())
    return;
  for (ObjCCategoryDecl::method_iterator i = CAT->meth_begin(Context),
       e =  CAT->meth_end(Context); i != e; ++i) {
    ObjCMethodDecl *Method = *i;
    const ObjCMethodDecl *&PrevMethod = MethodMap[Method->getSelector()];
    if (PrevMethod && !MatchTwoMethodDeclarations(Method, PrevMethod)) {
      Diag(Method->getLocation(), diag::err_duplicate_method_decl)
            << Method->getDeclName();
      Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
    }
  }
}

/// ActOnForwardProtocolDeclaration - Handle @protocol foo;
Action::DeclPtrTy
Sema::ActOnForwardProtocolDeclaration(SourceLocation AtProtocolLoc,
                                      const IdentifierLocPair *IdentList,
                                      unsigned NumElts,
                                      AttributeList *attrList) {
  llvm::SmallVector<ObjCProtocolDecl*, 32> Protocols;
  
  for (unsigned i = 0; i != NumElts; ++i) {
    IdentifierInfo *Ident = IdentList[i].first;
    ObjCProtocolDecl *&PDecl = ObjCProtocols[Ident];
    if (PDecl == 0) { // Not already seen?
      PDecl = ObjCProtocolDecl::Create(Context, CurContext, 
                                       IdentList[i].second, Ident);
      // FIXME: PushOnScopeChains?
      CurContext->addDecl(Context, PDecl);
    }
    if (attrList)
      ProcessDeclAttributeList(PDecl, attrList);
    Protocols.push_back(PDecl);
  }
  
  ObjCForwardProtocolDecl *PDecl = 
    ObjCForwardProtocolDecl::Create(Context, CurContext, AtProtocolLoc,
                                    &Protocols[0], Protocols.size());
  CurContext->addDecl(Context, PDecl);
  CheckObjCDeclScope(PDecl);
  return DeclPtrTy::make(PDecl);
}

Sema::DeclPtrTy Sema::
ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
                            IdentifierInfo *ClassName, SourceLocation ClassLoc,
                            IdentifierInfo *CategoryName,
                            SourceLocation CategoryLoc,
                            const DeclPtrTy *ProtoRefs,
                            unsigned NumProtoRefs,
                            SourceLocation EndProtoLoc) {
  ObjCCategoryDecl *CDecl = 
    ObjCCategoryDecl::Create(Context, CurContext, AtInterfaceLoc, CategoryName);
  // FIXME: PushOnScopeChains?
  CurContext->addDecl(Context, CDecl);

  ObjCInterfaceDecl *IDecl = getObjCInterfaceDecl(ClassName);
  /// Check that class of this category is already completely declared.
  if (!IDecl || IDecl->isForwardDecl()) {
    CDecl->setInvalidDecl();
    Diag(ClassLoc, diag::err_undef_interface) << ClassName;
    return DeclPtrTy::make(CDecl);
  }

  CDecl->setClassInterface(IDecl);
  
  // If the interface is deprecated, warn about it.
  (void)DiagnoseUseOfDecl(IDecl, ClassLoc);

  /// Check for duplicate interface declaration for this category
  ObjCCategoryDecl *CDeclChain;
  for (CDeclChain = IDecl->getCategoryList(); CDeclChain;
       CDeclChain = CDeclChain->getNextClassCategory()) {
    if (CategoryName && CDeclChain->getIdentifier() == CategoryName) {
      Diag(CategoryLoc, diag::warn_dup_category_def)
      << ClassName << CategoryName;
      Diag(CDeclChain->getLocation(), diag::note_previous_definition);
      break;
    }
  }
  if (!CDeclChain)
    CDecl->insertNextClassCategory();

  if (NumProtoRefs) {
    CDecl->setProtocolList((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs,Context);
    CDecl->setLocEnd(EndProtoLoc);
  }
  
  CheckObjCDeclScope(CDecl);
  return DeclPtrTy::make(CDecl);
}

/// ActOnStartCategoryImplementation - Perform semantic checks on the
/// category implementation declaration and build an ObjCCategoryImplDecl
/// object.
Sema::DeclPtrTy Sema::ActOnStartCategoryImplementation(
                      SourceLocation AtCatImplLoc,
                      IdentifierInfo *ClassName, SourceLocation ClassLoc,
                      IdentifierInfo *CatName, SourceLocation CatLoc) {
  ObjCInterfaceDecl *IDecl = getObjCInterfaceDecl(ClassName);
  ObjCCategoryImplDecl *CDecl = 
    ObjCCategoryImplDecl::Create(Context, CurContext, AtCatImplLoc, CatName,
                                 IDecl);
  /// Check that class of this category is already completely declared.
  if (!IDecl || IDecl->isForwardDecl())
    Diag(ClassLoc, diag::err_undef_interface) << ClassName;

  // FIXME: PushOnScopeChains?
  CurContext->addDecl(Context, CDecl);

  /// TODO: Check that CatName, category name, is not used in another
  // implementation.
  ObjCCategoryImpls.push_back(CDecl);
  
  CheckObjCDeclScope(CDecl);
  return DeclPtrTy::make(CDecl);
}

Sema::DeclPtrTy Sema::ActOnStartClassImplementation(
                      SourceLocation AtClassImplLoc,
                      IdentifierInfo *ClassName, SourceLocation ClassLoc,
                      IdentifierInfo *SuperClassname, 
                      SourceLocation SuperClassLoc) {
  ObjCInterfaceDecl* IDecl = 0;
  // Check for another declaration kind with the same name.
  NamedDecl *PrevDecl = LookupName(TUScope, ClassName, LookupOrdinaryName);
  if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
    Diag(ClassLoc, diag::err_redefinition_different_kind) << ClassName;
    Diag(PrevDecl->getLocation(), diag::note_previous_definition);
  }  else {
    // Is there an interface declaration of this class; if not, warn!
    IDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl); 
    if (!IDecl)
      Diag(ClassLoc, diag::warn_undef_interface) << ClassName;
  }
  
  // Check that super class name is valid class name
  ObjCInterfaceDecl* SDecl = 0;
  if (SuperClassname) {
    // Check if a different kind of symbol declared in this scope.
    PrevDecl = LookupName(TUScope, SuperClassname, LookupOrdinaryName);
    if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
      Diag(SuperClassLoc, diag::err_redefinition_different_kind)
        << SuperClassname;
      Diag(PrevDecl->getLocation(), diag::note_previous_definition);
    } else {
      SDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl); 
      if (!SDecl)
        Diag(SuperClassLoc, diag::err_undef_superclass)
          << SuperClassname << ClassName;
      else if (IDecl && IDecl->getSuperClass() != SDecl) {
        // This implementation and its interface do not have the same
        // super class.
        Diag(SuperClassLoc, diag::err_conflicting_super_class)
          << SDecl->getDeclName();
        Diag(SDecl->getLocation(), diag::note_previous_definition);
      }
    }
  }
  
  if (!IDecl) {
    // Legacy case of @implementation with no corresponding @interface.
    // Build, chain & install the interface decl into the identifier.

    // FIXME: Do we support attributes on the @implementation? If so
    // we should copy them over.
    IDecl = ObjCInterfaceDecl::Create(Context, CurContext, AtClassImplLoc, 
                                      ClassName, ClassLoc, false, true);
    ObjCInterfaceDecls[ClassName] = IDecl;
    IDecl->setSuperClass(SDecl);
    IDecl->setLocEnd(ClassLoc);
    
    // FIXME: PushOnScopeChains?
    CurContext->addDecl(Context, IDecl);
    // Remember that this needs to be removed when the scope is popped.
    TUScope->AddDecl(DeclPtrTy::make(IDecl));
  }
  
  ObjCImplementationDecl* IMPDecl = 
    ObjCImplementationDecl::Create(Context, CurContext, AtClassImplLoc, 
                                   IDecl, SDecl);
  
  // FIXME: PushOnScopeChains?
  CurContext->addDecl(Context, IMPDecl);

  if (CheckObjCDeclScope(IMPDecl))
    return DeclPtrTy::make(IMPDecl);
  
  // Check that there is no duplicate implementation of this class.
  if (ObjCImplementations[ClassName])
    // FIXME: Don't leak everything!
    Diag(ClassLoc, diag::err_dup_implementation_class) << ClassName;
  else // add it to the list.
    ObjCImplementations[ClassName] = IMPDecl;
  return DeclPtrTy::make(IMPDecl);
}

void Sema::CheckImplementationIvars(ObjCImplementationDecl *ImpDecl,
                                    ObjCIvarDecl **ivars, unsigned numIvars,
                                    SourceLocation RBrace) {
  assert(ImpDecl && "missing implementation decl");
  ObjCInterfaceDecl* IDecl = ImpDecl->getClassInterface();
  if (!IDecl)
    return;
  /// Check case of non-existing @interface decl.
  /// (legacy objective-c @implementation decl without an @interface decl).
  /// Add implementations's ivar to the synthesize class's ivar list.
  if (IDecl->ImplicitInterfaceDecl()) {
    IDecl->setIVarList(ivars, numIvars, Context);
    IDecl->setLocEnd(RBrace);
    return;
  }
  // If implementation has empty ivar list, just return.
  if (numIvars == 0)
    return;
  
  assert(ivars && "missing @implementation ivars");
  
  // Check interface's Ivar list against those in the implementation.
  // names and types must match.
  //
  unsigned j = 0;
  ObjCInterfaceDecl::ivar_iterator 
    IVI = IDecl->ivar_begin(), IVE = IDecl->ivar_end();
  for (; numIvars > 0 && IVI != IVE; ++IVI) {
    ObjCIvarDecl* ImplIvar = ivars[j++];
    ObjCIvarDecl* ClsIvar = *IVI;
    assert (ImplIvar && "missing implementation ivar");
    assert (ClsIvar && "missing class ivar");
    
    // First, make sure the types match.
    if (Context.getCanonicalType(ImplIvar->getType()) !=
        Context.getCanonicalType(ClsIvar->getType())) {
      Diag(ImplIvar->getLocation(), diag::err_conflicting_ivar_type)
        << ImplIvar->getIdentifier()
        << ImplIvar->getType() << ClsIvar->getType();
      Diag(ClsIvar->getLocation(), diag::note_previous_definition);
    } else if (ImplIvar->isBitField() && ClsIvar->isBitField()) {
      Expr *ImplBitWidth = ImplIvar->getBitWidth();
      Expr *ClsBitWidth = ClsIvar->getBitWidth();
      if (ImplBitWidth->getIntegerConstantExprValue(Context).getZExtValue() !=
          ClsBitWidth->getIntegerConstantExprValue(Context).getZExtValue()) {
        Diag(ImplBitWidth->getLocStart(), diag::err_conflicting_ivar_bitwidth)
          << ImplIvar->getIdentifier();
        Diag(ClsBitWidth->getLocStart(), diag::note_previous_definition);
      }
    } 
    // Make sure the names are identical.
    if (ImplIvar->getIdentifier() != ClsIvar->getIdentifier()) {
      Diag(ImplIvar->getLocation(), diag::err_conflicting_ivar_name)
        << ImplIvar->getIdentifier() << ClsIvar->getIdentifier();
      Diag(ClsIvar->getLocation(), diag::note_previous_definition);
    }
    --numIvars;
  }
  
  if (numIvars > 0)
    Diag(ivars[j]->getLocation(), diag::err_inconsistant_ivar_count);
  else if (IVI != IVE)
    Diag((*IVI)->getLocation(), diag::err_inconsistant_ivar_count);
}

void Sema::WarnUndefinedMethod(SourceLocation ImpLoc, ObjCMethodDecl *method,
                               bool &IncompleteImpl) {
  if (!IncompleteImpl) {
    Diag(ImpLoc, diag::warn_incomplete_impl);
    IncompleteImpl = true;
  }
  Diag(ImpLoc, diag::warn_undef_method_impl) << method->getDeclName();
}

void Sema::WarnConflictingTypedMethods(ObjCMethodDecl *ImpMethodDecl,
                                       ObjCMethodDecl *IntfMethodDecl) {
  if (!Context.typesAreCompatible(IntfMethodDecl->getResultType(),
                                  ImpMethodDecl->getResultType())) {
    Diag(ImpMethodDecl->getLocation(), diag::warn_conflicting_ret_types) 
      << ImpMethodDecl->getDeclName() << IntfMethodDecl->getResultType()
      << ImpMethodDecl->getResultType();
    Diag(IntfMethodDecl->getLocation(), diag::note_previous_definition);
  }
  
  for (ObjCMethodDecl::param_iterator IM = ImpMethodDecl->param_begin(),
       IF = IntfMethodDecl->param_begin(), EM = ImpMethodDecl->param_end();
       IM != EM; ++IM, ++IF) {
    if (Context.typesAreCompatible((*IF)->getType(), (*IM)->getType()))
      continue;
    
    Diag((*IM)->getLocation(), diag::warn_conflicting_param_types) 
      << ImpMethodDecl->getDeclName() << (*IF)->getType()
      << (*IM)->getType();
    Diag((*IF)->getLocation(), diag::note_previous_definition);
  }
}

/// isPropertyReadonly - Return true if property is readonly, by searching
/// for the property in the class and in its categories and implementations
///
bool Sema::isPropertyReadonly(ObjCPropertyDecl *PDecl,
                              ObjCInterfaceDecl *IDecl) {
  // by far the most common case.
  if (!PDecl->isReadOnly())
    return false;
  // Even if property is ready only, if interface has a user defined setter, 
  // it is not considered read only.
  if (IDecl->getInstanceMethod(Context, PDecl->getSetterName()))
    return false;
  
  // Main class has the property as 'readonly'. Must search
  // through the category list to see if the property's 
  // attribute has been over-ridden to 'readwrite'.
  for (ObjCCategoryDecl *Category = IDecl->getCategoryList();
       Category; Category = Category->getNextClassCategory()) {
    // Even if property is ready only, if a category has a user defined setter, 
    // it is not considered read only. 
    if (Category->getInstanceMethod(Context, PDecl->getSetterName()))
      return false;
    ObjCPropertyDecl *P = 
      Category->FindPropertyDeclaration(Context, PDecl->getIdentifier());
    if (P && !P->isReadOnly())
      return false;
  }
  
  // Also, check for definition of a setter method in the implementation if
  // all else failed.
  if (ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(CurContext)) {
    if (ObjCImplementationDecl *IMD = 
        dyn_cast<ObjCImplementationDecl>(OMD->getDeclContext())) {
      if (IMD->getInstanceMethod(PDecl->getSetterName()))
        return false;
    }
    else if (ObjCCategoryImplDecl *CIMD = 
             dyn_cast<ObjCCategoryImplDecl>(OMD->getDeclContext())) {
      if (CIMD->getInstanceMethod(PDecl->getSetterName()))
        return false;
    }
  }
  // Lastly, look through the implementation (if one is in scope).
  if (ObjCImplementationDecl *ImpDecl = 
        ObjCImplementations[IDecl->getIdentifier()])
    if (ImpDecl->getInstanceMethod(PDecl->getSetterName()))
      return false;
  // If all fails, look at the super class.
  if (ObjCInterfaceDecl *SIDecl = IDecl->getSuperClass())
    return isPropertyReadonly(PDecl, SIDecl);
  return true;
}

/// FIXME: Type hierarchies in Objective-C can be deep. We could most
/// likely improve the efficiency of selector lookups and type
/// checking by associating with each protocol / interface / category
/// the flattened instance tables. If we used an immutable set to keep
/// the table then it wouldn't add significant memory cost and it
/// would be handy for lookups.

/// CheckProtocolMethodDefs - This routine checks unimplemented methods
/// Declared in protocol, and those referenced by it.
void Sema::CheckProtocolMethodDefs(SourceLocation ImpLoc,
                                   ObjCProtocolDecl *PDecl,
                                   bool& IncompleteImpl,
                                   const llvm::DenseSet<Selector> &InsMap,
                                   const llvm::DenseSet<Selector> &ClsMap,
                                   ObjCInterfaceDecl *IDecl) {
  ObjCInterfaceDecl *Super = IDecl->getSuperClass();

  // If a method lookup fails locally we still need to look and see if
  // the method was implemented by a base class or an inherited
  // protocol. This lookup is slow, but occurs rarely in correct code
  // and otherwise would terminate in a warning.

  // check unimplemented instance methods.
  for (ObjCProtocolDecl::instmeth_iterator I = PDecl->instmeth_begin(Context), 
       E = PDecl->instmeth_end(Context); I != E; ++I) {
    ObjCMethodDecl *method = *I;
    if (method->getImplementationControl() != ObjCMethodDecl::Optional && 
        !method->isSynthesized() && !InsMap.count(method->getSelector()) &&
        (!Super || 
         !Super->lookupInstanceMethod(Context, method->getSelector()))) {
        // Ugly, but necessary. Method declared in protcol might have
        // have been synthesized due to a property declared in the class which
        // uses the protocol.
        ObjCMethodDecl *MethodInClass = 
          IDecl->lookupInstanceMethod(Context, method->getSelector());
        if (!MethodInClass || !MethodInClass->isSynthesized())
          WarnUndefinedMethod(ImpLoc, method, IncompleteImpl);
      }
  }
  // check unimplemented class methods
  for (ObjCProtocolDecl::classmeth_iterator 
         I = PDecl->classmeth_begin(Context),
         E = PDecl->classmeth_end(Context);
       I != E; ++I) {
    ObjCMethodDecl *method = *I;
    if (method->getImplementationControl() != ObjCMethodDecl::Optional &&
        !ClsMap.count(method->getSelector()) &&
        (!Super || !Super->lookupClassMethod(Context, method->getSelector())))
      WarnUndefinedMethod(ImpLoc, method, IncompleteImpl);
  }
  // Check on this protocols's referenced protocols, recursively.
  for (ObjCProtocolDecl::protocol_iterator PI = PDecl->protocol_begin(),
       E = PDecl->protocol_end(); PI != E; ++PI)
    CheckProtocolMethodDefs(ImpLoc, *PI, IncompleteImpl, InsMap, ClsMap, IDecl);
}

void Sema::ImplMethodsVsClassMethods(ObjCImplDecl* IMPDecl, 
                                     ObjCContainerDecl* CDecl, 
                                     bool IncompleteImpl) {
  llvm::DenseSet<Selector> InsMap;
  // Check and see if instance methods in class interface have been
  // implemented in the implementation class.
  for (ObjCImplementationDecl::instmeth_iterator I = IMPDecl->instmeth_begin(),
         E = IMPDecl->instmeth_end(); I != E; ++I)
    InsMap.insert((*I)->getSelector());
  
  for (ObjCInterfaceDecl::instmeth_iterator I = CDecl->instmeth_begin(Context),
       E = CDecl->instmeth_end(Context); I != E; ++I) {
    if (!(*I)->isSynthesized() && !InsMap.count((*I)->getSelector())) {
      WarnUndefinedMethod(IMPDecl->getLocation(), *I, IncompleteImpl);
      continue;
    }
    
    ObjCMethodDecl *ImpMethodDecl = 
      IMPDecl->getInstanceMethod((*I)->getSelector());
    ObjCMethodDecl *IntfMethodDecl = 
      CDecl->getInstanceMethod(Context, (*I)->getSelector());
    assert(IntfMethodDecl && 
           "IntfMethodDecl is null in ImplMethodsVsClassMethods");
    // ImpMethodDecl may be null as in a @dynamic property.
    if (ImpMethodDecl)
      WarnConflictingTypedMethods(ImpMethodDecl, IntfMethodDecl);
  }
      
  llvm::DenseSet<Selector> ClsMap;
  // Check and see if class methods in class interface have been
  // implemented in the implementation class.
  for (ObjCImplementationDecl::classmeth_iterator I =IMPDecl->classmeth_begin(),
       E = IMPDecl->classmeth_end(); I != E; ++I)
    ClsMap.insert((*I)->getSelector());
  
  for (ObjCInterfaceDecl::classmeth_iterator 
         I = CDecl->classmeth_begin(Context),
         E = CDecl->classmeth_end(Context);
       I != E; ++I)
    if (!ClsMap.count((*I)->getSelector()))
      WarnUndefinedMethod(IMPDecl->getLocation(), *I, IncompleteImpl);
    else {
      ObjCMethodDecl *ImpMethodDecl = 
        IMPDecl->getClassMethod((*I)->getSelector());
      ObjCMethodDecl *IntfMethodDecl = 
        CDecl->getClassMethod(Context, (*I)->getSelector());
      WarnConflictingTypedMethods(ImpMethodDecl, IntfMethodDecl);
    }
  
  
  // Check the protocol list for unimplemented methods in the @implementation
  // class.
  if (ObjCInterfaceDecl *I = dyn_cast<ObjCInterfaceDecl> (CDecl)) {
    for (ObjCCategoryDecl::protocol_iterator PI = I->protocol_begin(),
         E = I->protocol_end(); PI != E; ++PI)
      CheckProtocolMethodDefs(IMPDecl->getLocation(), *PI, IncompleteImpl, 
                              InsMap, ClsMap, I);
    // Check class extensions (unnamed categories)
    for (ObjCCategoryDecl *Categories = I->getCategoryList();
         Categories; Categories = Categories->getNextClassCategory()) {
      if (!Categories->getIdentifier()) {
        ImplMethodsVsClassMethods(IMPDecl, Categories, IncompleteImpl);
        break;
      }
    }
  } else if (ObjCCategoryDecl *C = dyn_cast<ObjCCategoryDecl>(CDecl)) {
    for (ObjCCategoryDecl::protocol_iterator PI = C->protocol_begin(),
         E = C->protocol_end(); PI != E; ++PI)
      CheckProtocolMethodDefs(IMPDecl->getLocation(), *PI, IncompleteImpl, 
                              InsMap, ClsMap, C->getClassInterface());
  } else
    assert(false && "invalid ObjCContainerDecl type.");
}

/// ActOnForwardClassDeclaration - 
Action::DeclPtrTy
Sema::ActOnForwardClassDeclaration(SourceLocation AtClassLoc,
                                   IdentifierInfo **IdentList,
                                   unsigned NumElts) {
  llvm::SmallVector<ObjCInterfaceDecl*, 32> Interfaces;
  
  for (unsigned i = 0; i != NumElts; ++i) {
    // Check for another declaration kind with the same name.
    NamedDecl *PrevDecl = LookupName(TUScope, IdentList[i], LookupOrdinaryName);
    if (PrevDecl && PrevDecl->isTemplateParameter()) {
      // Maybe we will complain about the shadowed template parameter.
      DiagnoseTemplateParameterShadow(AtClassLoc, PrevDecl);
      // Just pretend that we didn't see the previous declaration.
      PrevDecl = 0;
    }

    if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
      // GCC apparently allows the following idiom:
      //
      // typedef NSObject < XCElementTogglerP > XCElementToggler;
      // @class XCElementToggler;
      //
      // FIXME: Make an extension? 
      TypedefDecl *TDD = dyn_cast<TypedefDecl>(PrevDecl);
      if (!TDD || !isa<ObjCInterfaceType>(TDD->getUnderlyingType())) {
        Diag(AtClassLoc, diag::err_redefinition_different_kind) << IdentList[i];
        Diag(PrevDecl->getLocation(), diag::note_previous_definition);
      }
    }
    ObjCInterfaceDecl *IDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);