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/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Parse/DeclSpec.h"

using namespace clang;

/// ObjCActOnStartOfMethodDef - This routine sets up parameters; invisible
/// and user declared, in the method definition's AST.
void Sema::ObjCActOnStartOfMethodDef(Scope *FnBodyScope, DeclTy *D) {
  assert(getCurMethodDecl() == 0 && "Method parsing confused");
  ObjCMethodDecl *MDecl = dyn_cast_or_null<ObjCMethodDecl>((Decl *)D);
  
  // 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 (unsigned i = 0, e = MDecl->getNumParams(); i != e; ++i) {
    ParmVarDecl *PDecl = MDecl->getParamDecl(i);
    IdentifierInfo *II = PDecl->getIdentifier();
    if (II)
      PushOnScopeChains(PDecl, FnBodyScope);
  }
}

Sema::DeclTy *Sema::
ActOnStartClassInterface(SourceLocation AtInterfaceLoc,
                         IdentifierInfo *ClassName, SourceLocation ClassLoc,
                         IdentifierInfo *SuperName, SourceLocation SuperLoc,
                         DeclTy * const *ProtoRefs, unsigned NumProtoRefs,
                         SourceLocation EndProtoLoc, AttributeList *AttrList) {
  assert(ClassName && "Missing class identifier");
  
  // Check for another declaration kind with the same name.
  Decl *PrevDecl = LookupDecl(ClassName, Decl::IDNS_Ordinary, TUScope);
  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()) {
      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 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(IDecl);
  }
  
  if (SuperName) {
    ObjCInterfaceDecl* SuperClassEntry = 0;
    // Check if a different kind of symbol declared in this scope.
    PrevDecl = LookupDecl(SuperName, Decl::IDNS_Ordinary, TUScope);
    if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
      Diag(SuperLoc, diag::err_redefinition_different_kind) << SuperName;
      Diag(PrevDecl->getLocation(), diag::note_previous_definition);
    }
    else {
      // Check that super class is previously defined
      SuperClassEntry = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl); 

      if (!SuperClassEntry)
        Diag(SuperLoc, diag::err_undef_superclass)
          << SuperName << ClassName << SourceRange(AtInterfaceLoc, ClassLoc);
      else if (SuperClassEntry->isForwardDecl())
        Diag(SuperLoc, diag::err_undef_superclass)
          << SuperClassEntry->getDeclName() << ClassName
          << SourceRange(AtInterfaceLoc, ClassLoc);
    }
    IDecl->setSuperClass(SuperClassEntry);
    IDecl->setSuperClassLoc(SuperLoc);
    IDecl->setLocEnd(SuperLoc);
  } else { // we have a root class.
    IDecl->setLocEnd(ClassLoc);
  }
  
  /// Check then save referenced protocols.
  if (NumProtoRefs) {
    IDecl->addReferencedProtocols((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs);
    IDecl->setLocEnd(EndProtoLoc);
  }
  
  CheckObjCDeclScope(IDecl);
  return IDecl;
}

/// ActOnCompatiblityAlias - this action is called after complete parsing of
/// @compatibility_alias declaration. It sets up the alias relationships.
Sema::DeclTy *Sema::ActOnCompatiblityAlias(SourceLocation AtLoc,
                                           IdentifierInfo *AliasName, 
                                           SourceLocation AliasLocation,
                                           IdentifierInfo *ClassName,
                                           SourceLocation ClassLocation) {
  // Look for previous declaration of alias name
  Decl *ADecl = LookupDecl(AliasName, Decl::IDNS_Ordinary, TUScope);
  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 0;
  }
  // Check for class declaration
  Decl *CDeclU = LookupDecl(ClassName, Decl::IDNS_Ordinary, TUScope);
  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 = LookupDecl(ClassName, Decl::IDNS_Ordinary, TUScope);
      }
    }
  }
  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 0;
  }
  
  // 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(AliasDecl);

  return AliasDecl;
}

Sema::DeclTy *
Sema::ActOnStartProtocolInterface(SourceLocation AtProtoInterfaceLoc,
                                  IdentifierInfo *ProtocolName,
                                  SourceLocation ProtocolLoc,
                                  DeclTy * const *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::err_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 PDecl;
    }
    // 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->addReferencedProtocols((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs);
    PDecl->setLocEnd(EndProtoLoc);
  }
  
  CheckObjCDeclScope(PDecl);  
  return 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<DeclTy*> &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;
    }
    for (const Attr *attr = PDecl->getAttrs(); attr; attr = attr->getNext()) {
      if (attr->getKind() == Attr::Unavailable)
        Diag(ProtocolId[i].second, diag::warn_unavailable) << 
          PDecl->getDeclName();
      if (attr->getKind() == Attr::Deprecated)
        Diag(ProtocolId[i].second, diag::warn_deprecated) << 
          PDecl->getDeclName();
    }

    // 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(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;
  
  if (Context.getCanonicalType(Property->getType()) != 
          Context.getCanonicalType(SuperProperty->getType()))
    Diag(Property->getLocation(), diag::warn_property_type)
      << Property->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(),
       E = SDecl->prop_end(); S != E; ++S) {
    ObjCPropertyDecl *SuperPDecl = (*S);
    // Does property in super class has declaration in current class?
    for (ObjCInterfaceDecl::prop_iterator I = IDecl->prop_begin(),
         E = IDecl->prop_end(); 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) {
  llvm::SmallVector<ObjCPropertyDecl*, 16> mergeProperties;
  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(),
         E = PDecl->prop_end(); 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(), CE = CatDecl->prop_end(); 
           CP != CE; ++CP)
        if ((*CP)->getIdentifier() == Pr->getIdentifier())
          break;
      if (CP == CE)
        // Add this property to list of properties for thie class.
        mergeProperties.push_back(Pr);
      else
        // Property protocol already exist in class. Diagnose any mismatch.
        DiagnosePropertyMismatch((*CP), Pr, PDecl->getIdentifier());
    }
    CatDecl->mergeProperties(&mergeProperties[0], mergeProperties.size());
    return;
  }
  for (ObjCProtocolDecl::prop_iterator P = PDecl->prop_begin(),
       E = PDecl->prop_end(); 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(), CE = IDecl->prop_end(); 
         CP != CE; ++CP)
      if ((*CP)->getIdentifier() == Pr->getIdentifier())
        break;
    if (CP == CE)
      // Add this property to list of properties for thie class.
      mergeProperties.push_back(Pr);
    else
      // Property protocol already exist in class. Diagnose any mismatch.
      DiagnosePropertyMismatch((*CP), Pr, PDecl->getIdentifier());
    }
  IDecl->mergeProperties(&mergeProperties[0], mergeProperties.size());
}

/// 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,
                                       DeclTy *MergeItsProtocols) {
  Decl *ClassDecl = static_cast<Decl *>(MergeItsProtocols);
  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, *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, *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));
  }
}

/// ActOnForwardProtocolDeclaration - 
Action::DeclTy *
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 PDecl;
}

Sema::DeclTy *Sema::
ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
                            IdentifierInfo *ClassName, SourceLocation ClassLoc,
                            IdentifierInfo *CategoryName,
                            SourceLocation CategoryLoc,
                            DeclTy * const *ProtoRefs,
                            unsigned NumProtoRefs,
                            SourceLocation EndProtoLoc) {
  ObjCInterfaceDecl *IDecl = getObjCInterfaceDecl(ClassName);
  
  ObjCCategoryDecl *CDecl = 
    ObjCCategoryDecl::Create(Context, CurContext, AtInterfaceLoc, CategoryName);
  // FIXME: PushOnScopeChains?
  CurContext->addDecl(Context, CDecl);
  CDecl->setClassInterface(IDecl);
  
  /// Check that class of this category is already completely declared.
  if (!IDecl || IDecl->isForwardDecl())
    Diag(ClassLoc, diag::err_undef_interface) << ClassName;
  else {
    /// 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->addReferencedProtocols((ObjCProtocolDecl**)ProtoRefs, NumProtoRefs);
    CDecl->setLocEnd(EndProtoLoc);
  }
  
  CheckObjCDeclScope(CDecl);
  return CDecl;
}

/// ActOnStartCategoryImplementation - Perform semantic checks on the
/// category implementation declaration and build an ObjCCategoryImplDecl
/// object.
Sema::DeclTy *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 CDecl;
}

Sema::DeclTy *Sema::ActOnStartClassImplementation(
                      SourceLocation AtClassImplLoc,
                      IdentifierInfo *ClassName, SourceLocation ClassLoc,
                      IdentifierInfo *SuperClassname, 
                      SourceLocation SuperClassLoc) {
  ObjCInterfaceDecl* IDecl = 0;
  // Check for another declaration kind with the same name.
  Decl *PrevDecl = LookupDecl(ClassName, Decl::IDNS_Ordinary, TUScope);
  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 = LookupDecl(SuperClassname, Decl::IDNS_Ordinary, TUScope);
    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(IDecl);
  }
  
  ObjCImplementationDecl* IMPDecl = 
    ObjCImplementationDecl::Create(Context, CurContext, AtClassImplLoc, 
                                   ClassName, IDecl, SDecl);
  
  // FIXME: PushOnScopeChains?
  CurContext->addDecl(Context, IMPDecl);

  if (CheckObjCDeclScope(IMPDecl))
    return 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 IMPDecl;
}

void Sema::CheckImplementationIvars(ObjCImplementationDecl *ImpDecl,
                                    ObjCIvarDecl **ivars, unsigned numIvars,
                                    SourceLocation RBrace) {
  assert(ImpDecl && "missing implementation decl");
  ObjCInterfaceDecl* IDecl = getObjCInterfaceDecl(ImpDecl->getIdentifier());
  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->addInstanceVariablesToClass(ivars, numIvars, 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");
    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);
    }
    // TODO: Two mismatched (unequal width) Ivar bitfields should be diagnosed 
    // as error.
    else if (ImplIvar->getIdentifier() != ClsIvar->getIdentifier()) {
      Diag(ImplIvar->getLocation(), diag::err_conflicting_ivar_name)
        << ImplIvar->getIdentifier() << ClsIvar->getIdentifier();
      Diag(ClsIvar->getLocation(), diag::note_previous_definition);
      return;
    }
    --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) {
  bool err = false;
  QualType ImpMethodQType = 
    Context.getCanonicalType(ImpMethodDecl->getResultType());
  QualType IntfMethodQType = 
    Context.getCanonicalType(IntfMethodDecl->getResultType());
  if (!Context.typesAreCompatible(IntfMethodQType, ImpMethodQType))
    err = true;
  else for (ObjCMethodDecl::param_iterator IM=ImpMethodDecl->param_begin(),
            IF=IntfMethodDecl->param_begin(),
            EM=ImpMethodDecl->param_end(); IM!=EM; ++IM, IF++) {
    ImpMethodQType = Context.getCanonicalType((*IM)->getType());
    IntfMethodQType = Context.getCanonicalType((*IF)->getType());
    if (!Context.typesAreCompatible(IntfMethodQType, ImpMethodQType)) {
      err = true;
      break;
    }
  }
  if (err) {
    Diag(ImpMethodDecl->getLocation(), diag::warn_conflicting_types) 
    << ImpMethodDecl->getDeclName();
    Diag(IntfMethodDecl->getLocation(), diag::note_previous_definition);
  }
}

/// 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(), 
       E = PDecl->instmeth_end(); I != E; ++I) {
    ObjCMethodDecl *method = *I;
    if (method->getImplementationControl() != ObjCMethodDecl::Optional && 
        !method->isSynthesized() && !InsMap.count(method->getSelector()) &&
        (!Super || !Super->lookupInstanceMethod(method->getSelector())))
      WarnUndefinedMethod(ImpLoc, method, IncompleteImpl);
  }
  // check unimplemented class methods
  for (ObjCProtocolDecl::classmeth_iterator I = PDecl->classmeth_begin(), 
       E = PDecl->classmeth_end(); I != E; ++I) {
    ObjCMethodDecl *method = *I;
    if (method->getImplementationControl() != ObjCMethodDecl::Optional &&
        !ClsMap.count(method->getSelector()) &&
        (!Super || !Super->lookupClassMethod(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(ObjCImplementationDecl* IMPDecl, 
                                     ObjCInterfaceDecl* IDecl) {
  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());
  
  bool IncompleteImpl = false;
  for (ObjCInterfaceDecl::instmeth_iterator I = IDecl->instmeth_begin(),
       E = IDecl->instmeth_end(); I != E; ++I)
    if (!(*I)->isSynthesized() && !InsMap.count((*I)->getSelector()))
      WarnUndefinedMethod(IMPDecl->getLocation(), *I, IncompleteImpl);
    else {
      ObjCMethodDecl *ImpMethodDecl = 
        IMPDecl->getInstanceMethod((*I)->getSelector());
      ObjCMethodDecl *IntfMethodDecl = 
        IDecl->getInstanceMethod((*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 = IDecl->classmeth_begin(),
       E = IDecl->classmeth_end(); I != E; ++I)
    if (!ClsMap.count((*I)->getSelector()))
      WarnUndefinedMethod(IMPDecl->getLocation(), *I, IncompleteImpl);
    else {
      ObjCMethodDecl *ImpMethodDecl = 
        IMPDecl->getClassMethod((*I)->getSelector());
      ObjCMethodDecl *IntfMethodDecl = 
        IDecl->getClassMethod((*I)->getSelector());
      WarnConflictingTypedMethods(ImpMethodDecl, IntfMethodDecl);
    }
  
  
  // Check the protocol list for unimplemented methods in the @implementation
  // class.
  const ObjCList<ObjCProtocolDecl> &Protocols =
    IDecl->getReferencedProtocols();
  for (ObjCList<ObjCProtocolDecl>::iterator I = Protocols.begin(),
       E = Protocols.end(); I != E; ++I)
    CheckProtocolMethodDefs(IMPDecl->getLocation(), *I, 
                            IncompleteImpl, InsMap, ClsMap, IDecl);
}

/// ImplCategoryMethodsVsIntfMethods - Checks that methods declared in the
/// category interface are implemented in the category @implementation.
void Sema::ImplCategoryMethodsVsIntfMethods(ObjCCategoryImplDecl *CatImplDecl,
                                            ObjCCategoryDecl *CatClassDecl) {
  llvm::DenseSet<Selector> InsMap;
  // Check and see if instance methods in category interface have been
  // implemented in its implementation class.
  for (ObjCCategoryImplDecl::instmeth_iterator I =CatImplDecl->instmeth_begin(),
       E = CatImplDecl->instmeth_end(); I != E; ++I)
    InsMap.insert((*I)->getSelector());
  
  bool IncompleteImpl = false;
  for (ObjCCategoryDecl::instmeth_iterator I = CatClassDecl->instmeth_begin(),
       E = CatClassDecl->instmeth_end(); I != E; ++I)
    if (!(*I)->isSynthesized() && !InsMap.count((*I)->getSelector()))
      WarnUndefinedMethod(CatImplDecl->getLocation(), *I, IncompleteImpl);
    else {
      ObjCMethodDecl *ImpMethodDecl = 
        CatImplDecl->getInstanceMethod((*I)->getSelector());
      ObjCMethodDecl *IntfMethodDecl = 
        CatClassDecl->getInstanceMethod((*I)->getSelector());
      assert(IntfMethodDecl && 
             "IntfMethodDecl is null in ImplCategoryMethodsVsIntfMethods");
      // 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 category interface have been
  // implemented in its implementation class.
  for (ObjCCategoryImplDecl::classmeth_iterator
       I = CatImplDecl->classmeth_begin(), E = CatImplDecl->classmeth_end();
       I != E; ++I)
    ClsMap.insert((*I)->getSelector());
  
  for (ObjCCategoryDecl::classmeth_iterator I = CatClassDecl->classmeth_begin(),
       E = CatClassDecl->classmeth_end(); I != E; ++I)
    if (!ClsMap.count((*I)->getSelector()))
      WarnUndefinedMethod(CatImplDecl->getLocation(), *I, IncompleteImpl);
    else {
      ObjCMethodDecl *ImpMethodDecl = 
        CatImplDecl->getClassMethod((*I)->getSelector());
      ObjCMethodDecl *IntfMethodDecl = 
        CatClassDecl->getClassMethod((*I)->getSelector());
      WarnConflictingTypedMethods(ImpMethodDecl, IntfMethodDecl);
    }
  // Check the protocol list for unimplemented methods in the @implementation
  // class.
  for (ObjCCategoryDecl::protocol_iterator PI = CatClassDecl->protocol_begin(),
       E = CatClassDecl->protocol_end(); PI != E; ++PI)
    CheckProtocolMethodDefs(CatImplDecl->getLocation(), *PI, IncompleteImpl, 
                            InsMap, ClsMap, CatClassDecl->getClassInterface());
}

/// ActOnForwardClassDeclaration - 
Action::DeclTy *
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.
    Decl *PrevDecl = LookupDecl(IdentList[i], Decl::IDNS_Ordinary, TUScope);
    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); 
    if (!IDecl) {  // Not already seen?  Make a forward decl.
      IDecl = ObjCInterfaceDecl::Create(Context, CurContext, AtClassLoc, 
                                        IdentList[i], SourceLocation(), true);
      ObjCInterfaceDecls[IdentList[i]] = IDecl;

      // FIXME: PushOnScopeChains?
      CurContext->addDecl(Context, IDecl);
      // Remember that this needs to be removed when the scope is popped.
      TUScope->AddDecl(IDecl);
    }

    Interfaces.push_back(IDecl);
  }
  
  ObjCClassDecl *CDecl = ObjCClassDecl::Create(Context, CurContext, AtClassLoc,
                                               &Interfaces[0],
                                               Interfaces.size());
  CurContext->addDecl(Context, CDecl);
  CheckObjCDeclScope(CDecl);
  return CDecl;  
}


/// MatchTwoMethodDeclarations - Checks that two methods have matching type and
/// returns true, or false, accordingly.
/// TODO: Handle protocol list; such as id<p1,p2> in type comparisons
bool Sema::MatchTwoMethodDeclarations(const ObjCMethodDecl *Method, 
                                      const ObjCMethodDecl *PrevMethod,
                                      bool matchBasedOnSizeAndAlignment) {
  QualType T1 = Context.getCanonicalType(Method->getResultType());
  QualType T2 = Context.getCanonicalType(PrevMethod->getResultType());
  
  if (T1 != T2) {
    // The result types are different.
    if (!matchBasedOnSizeAndAlignment)
      return false;
    // Incomplete types don't have a size and alignment.
    if (T1->isIncompleteType() || T2->isIncompleteType())
      return false;
    // Check is based on size and alignment.
    if (Context.getTypeInfo(T1) != Context.getTypeInfo(T2))
      return false;
  }
  for (unsigned i = 0, e = Method->getNumParams(); i != e; ++i) {
    T1 = Context.getCanonicalType(Method->getParamDecl(i)->getType());
    T2 = Context.getCanonicalType(PrevMethod->getParamDecl(i)->getType());
    if (T1 != T2) {
      // The result types are different.
      if (!matchBasedOnSizeAndAlignment)
        return false;
      // Incomplete types don't have a size and alignment.
      if (T1->isIncompleteType() || T2->isIncompleteType())
        return false;
      // Check is based on size and alignment.
      if (Context.getTypeInfo(T1) != Context.getTypeInfo(T2))
        return false;
    }
  }
  return true;
}

void Sema::AddInstanceMethodToGlobalPool(ObjCMethodDecl *Method) {
  ObjCMethodList &FirstMethod = InstanceMethodPool[Method->getSelector()];
  if (!FirstMethod.Method) {
    // Haven't seen a method with this selector name yet - add it.
    FirstMethod.Method = Method;
    FirstMethod.Next = 0;
  } else {
    // We've seen a method with this name, now check the type signature(s).
    bool match = MatchTwoMethodDeclarations(Method, FirstMethod.Method);
    
    for (ObjCMethodList *Next = FirstMethod.Next; !match && Next; 
         Next = Next->Next)
      match = MatchTwoMethodDeclarations(Method, Next->Method);
      
    if (!match) {
      // We have a new signature for an existing method - add it.
      // This is extremely rare. Only 1% of Cocoa selectors are "overloaded".
      FirstMethod.Next = new ObjCMethodList(Method, FirstMethod.Next);;
    }
  }
}

// FIXME: Finish implementing -Wno-strict-selector-match.
ObjCMethodDecl *Sema::LookupInstanceMethodInGlobalPool(Selector Sel, 
                                                       SourceRange R) {
  ObjCMethodList &MethList = InstanceMethodPool[Sel];
  bool issueWarning = false;
  
  if (MethList.Method && MethList.Next) {
    for (ObjCMethodList *Next = MethList.Next; Next; Next = Next->Next)
      // This checks if the methods differ by size & alignment.
      if (!MatchTwoMethodDeclarations(MethList.Method, Next->Method, true))
        issueWarning = true;
  }
  if (issueWarning && (MethList.Method && MethList.Next)) {
    Diag(R.getBegin(), diag::warn_multiple_method_decl) << Sel << R;
    Diag(MethList.Method->getLocStart(), diag::note_using_decl)
      << MethList.Method->getSourceRange();
    for (ObjCMethodList *Next = MethList.Next; Next; Next = Next->Next)
      Diag(Next->Method->getLocStart(), diag::note_also_found_decl)
        << Next->Method->getSourceRange();