xref: /external/clang/lib/AST/DeclObjC.cpp

//===--- DeclObjC.cpp - ObjC Declaration AST Node Implementation ----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Objective-C related Decl classes.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/DeclObjC.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Stmt.h"
#include "llvm/ADT/STLExtras.h"
using namespace clang;

//===----------------------------------------------------------------------===//
// ObjCListBase
//===----------------------------------------------------------------------===//

void ObjCListBase::Destroy(ASTContext &Ctx) {
  Ctx.Deallocate(List);
  NumElts = 0;
  List = 0;
}

void ObjCListBase::set(void *const* InList, unsigned Elts, ASTContext &Ctx) {
  assert(List == 0 && "Elements already set!");
  if (Elts == 0) return;  // Setting to an empty list is a noop.


  List = new (Ctx) void*[Elts];
  NumElts = Elts;
  memcpy(List, InList, sizeof(void*)*Elts);
}


//===----------------------------------------------------------------------===//
// ObjCInterfaceDecl
//===----------------------------------------------------------------------===//

/// getIvarDecl - This method looks up an ivar in this ContextDecl.
///
ObjCIvarDecl *
ObjCContainerDecl::getIvarDecl(IdentifierInfo *Id) const {
  lookup_const_iterator Ivar, IvarEnd;
  for (llvm::tie(Ivar, IvarEnd) = lookup(Id); Ivar != IvarEnd; ++Ivar) {
    if (ObjCIvarDecl *ivar = dyn_cast<ObjCIvarDecl>(*Ivar))
      return ivar;
  }
  return 0;
}

// Get the local instance method declared in this interface.
ObjCMethodDecl *
ObjCContainerDecl::getInstanceMethod(Selector Sel) const {
  // Since instance & class methods can have the same name, the loop below
  // ensures we get the correct method.
  //
  // @interface Whatever
  // - (int) class_method;
  // + (float) class_method;
  // @end
  //
  lookup_const_iterator Meth, MethEnd;
  for (llvm::tie(Meth, MethEnd) = lookup(Sel); Meth != MethEnd; ++Meth) {
    ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(*Meth);
    if (MD && MD->isInstanceMethod())
      return MD;
  }
  return 0;
}

// Get the local class method declared in this interface.
ObjCMethodDecl *
ObjCContainerDecl::getClassMethod(Selector Sel) const {
  // Since instance & class methods can have the same name, the loop below
  // ensures we get the correct method.
  //
  // @interface Whatever
  // - (int) class_method;
  // + (float) class_method;
  // @end
  //
  lookup_const_iterator Meth, MethEnd;
  for (llvm::tie(Meth, MethEnd) = lookup(Sel); Meth != MethEnd; ++Meth) {
    ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(*Meth);
    if (MD && MD->isClassMethod())
      return MD;
  }
  return 0;
}

/// FindPropertyDeclaration - Finds declaration of the property given its name
/// in 'PropertyId' and returns it. It returns 0, if not found.
/// FIXME: Convert to DeclContext lookup...
///
ObjCPropertyDecl *
ObjCContainerDecl::FindPropertyDeclaration(IdentifierInfo *PropertyId) const {
  for (prop_iterator I = prop_begin(), E = prop_end(); I != E; ++I)
    if ((*I)->getIdentifier() == PropertyId)
      return *I;

  const ObjCProtocolDecl *PID = dyn_cast<ObjCProtocolDecl>(this);
  if (PID) {
    for (ObjCProtocolDecl::protocol_iterator I = PID->protocol_begin(),
         E = PID->protocol_end(); I != E; ++I)
      if (ObjCPropertyDecl *P = (*I)->FindPropertyDeclaration(PropertyId))
        return P;
  }

  if (const ObjCInterfaceDecl *OID = dyn_cast<ObjCInterfaceDecl>(this)) {
    // Look through categories.
    for (ObjCCategoryDecl *Category = OID->getCategoryList();
         Category; Category = Category->getNextClassCategory()) {
      if (ObjCPropertyDecl *P = Category->FindPropertyDeclaration(PropertyId))
        return P;
    }
    // Look through protocols.
    for (ObjCInterfaceDecl::protocol_iterator I = OID->protocol_begin(),
         E = OID->protocol_end(); I != E; ++I) {
      if (ObjCPropertyDecl *P = (*I)->FindPropertyDeclaration(PropertyId))
        return P;
    }
    if (OID->getSuperClass())
      return OID->getSuperClass()->FindPropertyDeclaration(PropertyId);
  } else if (const ObjCCategoryDecl *OCD = dyn_cast<ObjCCategoryDecl>(this)) {
    // Look through protocols.
    for (ObjCInterfaceDecl::protocol_iterator I = OCD->protocol_begin(),
         E = OCD->protocol_end(); I != E; ++I) {
      if (ObjCPropertyDecl *P = (*I)->FindPropertyDeclaration(PropertyId))
        return P;
    }
  }
  return 0;
}

ObjCIvarDecl *ObjCInterfaceDecl::lookupInstanceVariable(IdentifierInfo *ID,
                                              ObjCInterfaceDecl *&clsDeclared) {
  ObjCInterfaceDecl* ClassDecl = this;
  while (ClassDecl != NULL) {
    if (ObjCIvarDecl *I = ClassDecl->getIvarDecl(ID)) {
      clsDeclared = ClassDecl;
      return I;
    }
    ClassDecl = ClassDecl->getSuperClass();
  }
  return NULL;
}

/// lookupInheritedClass - This method returns ObjCInterfaceDecl * of the super
/// class whose name is passed as argument. If it is not one of the super classes
/// the it returns NULL.
ObjCInterfaceDecl *ObjCInterfaceDecl::lookupInheritedClass(
                                        const IdentifierInfo*ICName) {
  ObjCInterfaceDecl* ClassDecl = this;
  while (ClassDecl != NULL) {
    if (ClassDecl->getIdentifier() == ICName)
      return ClassDecl;
    ClassDecl = ClassDecl->getSuperClass();
  }
  return NULL;
}

/// lookupInstanceMethod - This method returns an instance method by looking in
/// the class, its categories, and its super classes (using a linear search).
ObjCMethodDecl *ObjCInterfaceDecl::lookupInstanceMethod(Selector Sel) {
  ObjCInterfaceDecl* ClassDecl = this;
  ObjCMethodDecl *MethodDecl = 0;

  while (ClassDecl != NULL) {
    if ((MethodDecl = ClassDecl->getInstanceMethod(Sel)))
      return MethodDecl;

    // Didn't find one yet - look through protocols.
    const ObjCList<ObjCProtocolDecl> &Protocols =
      ClassDecl->getReferencedProtocols();
    for (ObjCList<ObjCProtocolDecl>::iterator I = Protocols.begin(),
         E = Protocols.end(); I != E; ++I)
      if ((MethodDecl = (*I)->lookupInstanceMethod(Sel)))
        return MethodDecl;

    // Didn't find one yet - now look through categories.
    ObjCCategoryDecl *CatDecl = ClassDecl->getCategoryList();
    while (CatDecl) {
      if ((MethodDecl = CatDecl->getInstanceMethod(Sel)))
        return MethodDecl;

      // Didn't find one yet - look through protocols.
      const ObjCList<ObjCProtocolDecl> &Protocols =
        CatDecl->getReferencedProtocols();
      for (ObjCList<ObjCProtocolDecl>::iterator I = Protocols.begin(),
           E = Protocols.end(); I != E; ++I)
        if ((MethodDecl = (*I)->lookupInstanceMethod(Sel)))
          return MethodDecl;
      CatDecl = CatDecl->getNextClassCategory();
    }
    ClassDecl = ClassDecl->getSuperClass();
  }
  return NULL;
}

// lookupClassMethod - This method returns a class method by looking in the
// class, its categories, and its super classes (using a linear search).
ObjCMethodDecl *ObjCInterfaceDecl::lookupClassMethod(Selector Sel) {
  ObjCInterfaceDecl* ClassDecl = this;
  ObjCMethodDecl *MethodDecl = 0;

  while (ClassDecl != NULL) {
    if ((MethodDecl = ClassDecl->getClassMethod(Sel)))
      return MethodDecl;

    // Didn't find one yet - look through protocols.
    for (ObjCInterfaceDecl::protocol_iterator I = ClassDecl->protocol_begin(),
         E = ClassDecl->protocol_end(); I != E; ++I)
      if ((MethodDecl = (*I)->lookupClassMethod(Sel)))
        return MethodDecl;

    // Didn't find one yet - now look through categories.
    ObjCCategoryDecl *CatDecl = ClassDecl->getCategoryList();
    while (CatDecl) {
      if ((MethodDecl = CatDecl->getClassMethod(Sel)))
        return MethodDecl;

      // Didn't find one yet - look through protocols.
      const ObjCList<ObjCProtocolDecl> &Protocols =
        CatDecl->getReferencedProtocols();
      for (ObjCList<ObjCProtocolDecl>::iterator I = Protocols.begin(),
           E = Protocols.end(); I != E; ++I)
        if ((MethodDecl = (*I)->lookupClassMethod(Sel)))
          return MethodDecl;
      CatDecl = CatDecl->getNextClassCategory();
    }
    ClassDecl = ClassDecl->getSuperClass();
  }
  return NULL;
}



//===----------------------------------------------------------------------===//
// ObjCMethodDecl
//===----------------------------------------------------------------------===//

ObjCMethodDecl *ObjCMethodDecl::Create(ASTContext &C,
                                       SourceLocation beginLoc,
                                       SourceLocation endLoc,
                                       Selector SelInfo, QualType T,
                                       DeclContext *contextDecl,
                                       bool isInstance,
                                       bool isVariadic,
                                       bool isSynthesized,
                                       ImplementationControl impControl) {
  return new (C) ObjCMethodDecl(beginLoc, endLoc,
                                  SelInfo, T, contextDecl,
                                  isInstance,
                                  isVariadic, isSynthesized, impControl);
}

void ObjCMethodDecl::Destroy(ASTContext &C) {
  if (Body) Body->Destroy(C);
  if (SelfDecl) SelfDecl->Destroy(C);

  for (param_iterator I=param_begin(), E=param_end(); I!=E; ++I)
    if (*I) (*I)->Destroy(C);

  ParamInfo.Destroy(C);

  Decl::Destroy(C);
}

void ObjCMethodDecl::createImplicitParams(ASTContext &Context,
                                          const ObjCInterfaceDecl *OID) {
  QualType selfTy;
  if (isInstanceMethod()) {
    // There may be no interface context due to error in declaration
    // of the interface (which has been reported). Recover gracefully.
    if (OID) {
      selfTy = Context.getObjCInterfaceType(OID);
      selfTy = Context.getObjCObjectPointerType(selfTy);
    } else {
      selfTy = Context.getObjCIdType();
    }
  } else // we have a factory method.
    selfTy = Context.getObjCClassType();

  setSelfDecl(ImplicitParamDecl::Create(Context, this, SourceLocation(),
                                        &Context.Idents.get("self"), selfTy));

  setCmdDecl(ImplicitParamDecl::Create(Context, this, SourceLocation(),
                                       &Context.Idents.get("_cmd"),
                                       Context.getObjCSelType()));
}



/// getSynthesizedMethodSize - Compute size of synthesized method name
/// as done be the rewrite.
///
unsigned ObjCMethodDecl::getSynthesizedMethodSize() const {
  // syntesized method name is a concatenation of -/+[class-name selector]
  // Get length of this name.
  unsigned length = 3;  // _I_ or _C_
  length += getClassInterface()->getNameAsString().size()+1; // extra for _
  if (const ObjCCategoryImplDecl *CID =
      dyn_cast<ObjCCategoryImplDecl>(getDeclContext()))
    length += CID->getNameAsString().size()+1;
  length += getSelector().getAsString().size(); // selector name
  return length;
}

ObjCInterfaceDecl *ObjCMethodDecl::getClassInterface() {
  if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(getDeclContext()))
    return ID;
  if (ObjCCategoryDecl *CD = dyn_cast<ObjCCategoryDecl>(getDeclContext()))
    return CD->getClassInterface();
  if (ObjCImplementationDecl *IMD =
      dyn_cast<ObjCImplementationDecl>(getDeclContext()))
    return IMD->getClassInterface();
  if (ObjCCategoryImplDecl *CID =
      dyn_cast<ObjCCategoryImplDecl>(getDeclContext()))
    return CID->getClassInterface();
  assert(false && "unknown method context");
  return 0;
}

//===----------------------------------------------------------------------===//
// ObjCInterfaceDecl
//===----------------------------------------------------------------------===//

ObjCInterfaceDecl *ObjCInterfaceDecl::Create(ASTContext &C,
                                             DeclContext *DC,
                                             SourceLocation atLoc,
                                             IdentifierInfo *Id,
                                             SourceLocation ClassLoc,
                                             bool ForwardDecl, bool isInternal){
  return new (C) ObjCInterfaceDecl(DC, atLoc, Id, ClassLoc, ForwardDecl,
                                     isInternal);
}

ObjCInterfaceDecl::
ObjCInterfaceDecl(DeclContext *DC, SourceLocation atLoc, IdentifierInfo *Id,
                  SourceLocation CLoc, bool FD, bool isInternal)
  : ObjCContainerDecl(ObjCInterface, DC, atLoc, Id),
    TypeForDecl(0), SuperClass(0),
    CategoryList(0), ForwardDecl(FD), InternalInterface(isInternal),
    ClassLoc(CLoc) {
}

void ObjCInterfaceDecl::Destroy(ASTContext &C) {
  for (ivar_iterator I = ivar_begin(), E = ivar_end(); I != E; ++I)
    if (*I) (*I)->Destroy(C);

  IVars.Destroy(C);
  // FIXME: CategoryList?

  // FIXME: Because there is no clear ownership
  //  role between ObjCInterfaceDecls and the ObjCPropertyDecls that they
  //  reference, we destroy ObjCPropertyDecls in ~TranslationUnit.
  Decl::Destroy(C);
}

ObjCImplementationDecl *ObjCInterfaceDecl::getImplementation() const {
  return getASTContext().getObjCImplementation(
                                          const_cast<ObjCInterfaceDecl*>(this));
}

void ObjCInterfaceDecl::setImplementation(ObjCImplementationDecl *ImplD) {
  getASTContext().setObjCImplementation(this, ImplD);
}


/// FindCategoryDeclaration - Finds category declaration in the list of
/// categories for this class and returns it. Name of the category is passed
/// in 'CategoryId'. If category not found, return 0;
///
ObjCCategoryDecl *
ObjCInterfaceDecl::FindCategoryDeclaration(IdentifierInfo *CategoryId) const {
  for (ObjCCategoryDecl *Category = getCategoryList();
       Category; Category = Category->getNextClassCategory())
    if (Category->getIdentifier() == CategoryId)
      return Category;
  return 0;
}

//===----------------------------------------------------------------------===//
// ObjCIvarDecl
//===----------------------------------------------------------------------===//

ObjCIvarDecl *ObjCIvarDecl::Create(ASTContext &C, DeclContext *DC,
                                   SourceLocation L, IdentifierInfo *Id,
                                   QualType T, AccessControl ac, Expr *BW) {
  return new (C) ObjCIvarDecl(DC, L, Id, T, ac, BW);
}



//===----------------------------------------------------------------------===//
// ObjCAtDefsFieldDecl
//===----------------------------------------------------------------------===//

ObjCAtDefsFieldDecl
*ObjCAtDefsFieldDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L,
                             IdentifierInfo *Id, QualType T, Expr *BW) {
  return new (C) ObjCAtDefsFieldDecl(DC, L, Id, T, BW);
}

void ObjCAtDefsFieldDecl::Destroy(ASTContext& C) {
  this->~ObjCAtDefsFieldDecl();
  C.Deallocate((void *)this);
}

//===----------------------------------------------------------------------===//
// ObjCProtocolDecl
//===----------------------------------------------------------------------===//

ObjCProtocolDecl *ObjCProtocolDecl::Create(ASTContext &C, DeclContext *DC,
                                           SourceLocation L,
                                           IdentifierInfo *Id) {
  return new (C) ObjCProtocolDecl(DC, L, Id);
}

void ObjCProtocolDecl::Destroy(ASTContext &C) {
  ReferencedProtocols.Destroy(C);
  ObjCContainerDecl::Destroy(C);
}

ObjCProtocolDecl *ObjCProtocolDecl::lookupProtocolNamed(IdentifierInfo *Name) {
  ObjCProtocolDecl *PDecl = this;

  if (Name == getIdentifier())
    return PDecl;

  for (protocol_iterator I = protocol_begin(), E = protocol_end(); I != E; ++I)
    if ((PDecl = (*I)->lookupProtocolNamed(Name)))
      return PDecl;

  return NULL;
}

// lookupInstanceMethod - Lookup a instance method in the protocol and protocols
// it inherited.
ObjCMethodDecl *ObjCProtocolDecl::lookupInstanceMethod(Selector Sel) {
  ObjCMethodDecl *MethodDecl = NULL;

  if ((MethodDecl = getInstanceMethod(Sel)))
    return MethodDecl;

  for (protocol_iterator I = protocol_begin(), E = protocol_end(); I != E; ++I)
    if ((MethodDecl = (*I)->lookupInstanceMethod(Sel)))
      return MethodDecl;
  return NULL;
}

// lookupInstanceMethod - Lookup a class method in the protocol and protocols
// it inherited.
ObjCMethodDecl *ObjCProtocolDecl::lookupClassMethod(Selector Sel) {
  ObjCMethodDecl *MethodDecl = NULL;

  if ((MethodDecl = getClassMethod(Sel)))
    return MethodDecl;

  for (protocol_iterator I = protocol_begin(), E = protocol_end(); I != E; ++I)
    if ((MethodDecl = (*I)->lookupClassMethod(Sel)))
      return MethodDecl;
  return NULL;
}

//===----------------------------------------------------------------------===//
// ObjCClassDecl
//===----------------------------------------------------------------------===//

ObjCClassDecl::ObjCClassDecl(DeclContext *DC, SourceLocation L,
                             ObjCInterfaceDecl *const *Elts, unsigned nElts,
                             ASTContext &C)
  : Decl(ObjCClass, DC, L) {
  ForwardDecls.set(Elts, nElts, C);
}


ObjCClassDecl *ObjCClassDecl::Create(ASTContext &C, DeclContext *DC,
                                     SourceLocation L,
                                     ObjCInterfaceDecl *const *Elts,
                                     unsigned nElts) {
  return new (C) ObjCClassDecl(DC, L, Elts, nElts, C);
}

void ObjCClassDecl::Destroy(ASTContext &C) {

  // FIXME: There is no clear ownership policy now for referenced
  //  ObjCInterfaceDecls.  Some of them can be forward declarations that
  //  are never later defined (in which case the ObjCClassDecl owns them)
  //  or the ObjCInterfaceDecl later becomes a real definition later.  Ideally
  //  we should have separate objects for forward declarations and definitions,
  //  obviating this problem.  Because of this situation, referenced
  //  ObjCInterfaceDecls are destroyed in ~TranslationUnit.

  ForwardDecls.Destroy(C);
  Decl::Destroy(C);
}

//===----------------------------------------------------------------------===//
// ObjCForwardProtocolDecl
//===----------------------------------------------------------------------===//

ObjCForwardProtocolDecl::
ObjCForwardProtocolDecl(DeclContext *DC, SourceLocation L,
                        ObjCProtocolDecl *const *Elts, unsigned nElts,
                        ASTContext &C)
: Decl(ObjCForwardProtocol, DC, L) {
  ReferencedProtocols.set(Elts, nElts, C);
}


ObjCForwardProtocolDecl *
ObjCForwardProtocolDecl::Create(ASTContext &C, DeclContext *DC,
                                SourceLocation L,
                                ObjCProtocolDecl *const *Elts,
                                unsigned NumElts) {
  return new (C) ObjCForwardProtocolDecl(DC, L, Elts, NumElts, C);
}

void ObjCForwardProtocolDecl::Destroy(ASTContext &C) {
  ReferencedProtocols.Destroy(C);
  Decl::Destroy(C);
}

//===----------------------------------------------------------------------===//
// ObjCCategoryDecl
//===----------------------------------------------------------------------===//

ObjCCategoryDecl *ObjCCategoryDecl::Create(ASTContext &C, DeclContext *DC,
                                           SourceLocation L,
                                           IdentifierInfo *Id) {
  return new (C) ObjCCategoryDecl(DC, L, Id);
}

ObjCCategoryImplDecl *ObjCCategoryDecl::getImplementation() const {
  return getASTContext().getObjCImplementation(
                                           const_cast<ObjCCategoryDecl*>(this));
}

void ObjCCategoryDecl::setImplementation(ObjCCategoryImplDecl *ImplD) {
  getASTContext().setObjCImplementation(this, ImplD);
}


//===----------------------------------------------------------------------===//
// ObjCCategoryImplDecl
//===----------------------------------------------------------------------===//

ObjCCategoryImplDecl *
ObjCCategoryImplDecl::Create(ASTContext &C, DeclContext *DC,
                             SourceLocation L,IdentifierInfo *Id,
                             ObjCInterfaceDecl *ClassInterface) {
  return new (C) ObjCCategoryImplDecl(DC, L, Id, ClassInterface);
}


void ObjCImplDecl::addPropertyImplementation(ObjCPropertyImplDecl *property) {
  // FIXME: The context should be correct before we get here.
  property->setLexicalDeclContext(this);
  addDecl(property);
}

void ObjCImplDecl::setClassInterface(ObjCInterfaceDecl *IFace) {
  ASTContext &Ctx = getASTContext();

  if (ObjCImplementationDecl *ImplD
        = dyn_cast_or_null<ObjCImplementationDecl>(this))
    if (IFace)
      Ctx.setObjCImplementation(IFace, ImplD);

  else if (ObjCCategoryImplDecl *ImplD =
             dyn_cast_or_null<ObjCCategoryImplDecl>(this)) {
    if (ObjCCategoryDecl *CD = IFace->FindCategoryDeclaration(getIdentifier()))
      Ctx.setObjCImplementation(CD, ImplD);
  }

  ClassInterface = IFace;
}

/// FindPropertyImplIvarDecl - This method lookup the ivar in the list of
/// properties implemented in this category @implementation block and returns
/// the implemented property that uses it.
///
ObjCPropertyImplDecl *ObjCImplDecl::
FindPropertyImplIvarDecl(IdentifierInfo *ivarId) const {
  for (propimpl_iterator i = propimpl_begin(), e = propimpl_end(); i != e; ++i){
    ObjCPropertyImplDecl *PID = *i;
    if (PID->getPropertyIvarDecl() &&
        PID->getPropertyIvarDecl()->getIdentifier() == ivarId)
      return PID;
  }
  return 0;
}

/// FindPropertyImplDecl - This method looks up a previous ObjCPropertyImplDecl
/// added to the list of those properties @synthesized/@dynamic in this
/// category @implementation block.
///
ObjCPropertyImplDecl *ObjCImplDecl::
FindPropertyImplDecl(IdentifierInfo *Id) const {
  for (propimpl_iterator i = propimpl_begin(), e = propimpl_end(); i != e; ++i){
    ObjCPropertyImplDecl *PID = *i;
    if (PID->getPropertyDecl()->getIdentifier() == Id)
      return PID;
  }
  return 0;
}

// getInstanceMethod - This method returns an instance method by looking in
// the class implementation. Unlike interfaces, we don't look outside the
// implementation.
ObjCMethodDecl *ObjCImplDecl::getInstanceMethod(Selector Sel) const {
  // Since instance & class methods can have the same name, the loop below
  // ensures we get the correct method.
  //
  // @interface Whatever
  // - (int) class_method;
  // + (float) class_method;
  // @end
  //
  lookup_const_iterator Meth, MethEnd;
  for (llvm::tie(Meth, MethEnd) = lookup(Sel);
       Meth != MethEnd; ++Meth) {
    ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(*Meth);
    if (MD && MD->isInstanceMethod())
      return MD;
  }
  return 0;
}

// getClassMethod - This method returns an instance method by looking in
// the class implementation. Unlike interfaces, we don't look outside the
// implementation.
ObjCMethodDecl *ObjCImplDecl::getClassMethod(Selector Sel) const {
  // Since instance & class methods can have the same name, the loop below
  // ensures we get the correct method.
  //
  // @interface Whatever
  // - (int) class_method;
  // + (float) class_method;
  // @end
  //
  lookup_const_iterator Meth, MethEnd;
  for (llvm::tie(Meth, MethEnd) = lookup(Sel);
       Meth != MethEnd; ++Meth) {
    ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(*Meth);
    if (MD && MD->isClassMethod())
      return MD;
  }
  return 0;
}

//===----------------------------------------------------------------------===//
// ObjCImplementationDecl
//===----------------------------------------------------------------------===//

ObjCImplementationDecl *
ObjCImplementationDecl::Create(ASTContext &C, DeclContext *DC,
                               SourceLocation L,
                               ObjCInterfaceDecl *ClassInterface,
                               ObjCInterfaceDecl *SuperDecl) {
  return new (C) ObjCImplementationDecl(DC, L, ClassInterface, SuperDecl);
}

//===----------------------------------------------------------------------===//
// ObjCCompatibleAliasDecl
//===----------------------------------------------------------------------===//

ObjCCompatibleAliasDecl *
ObjCCompatibleAliasDecl::Create(ASTContext &C, DeclContext *DC,
                                SourceLocation L,
                                IdentifierInfo *Id,
                                ObjCInterfaceDecl* AliasedClass) {
  return new (C) ObjCCompatibleAliasDecl(DC, L, Id, AliasedClass);
}

//===----------------------------------------------------------------------===//
// ObjCPropertyDecl
//===----------------------------------------------------------------------===//

ObjCPropertyDecl *ObjCPropertyDecl::Create(ASTContext &C, DeclContext *DC,
                                           SourceLocation L,
                                           IdentifierInfo *Id,
                                           QualType T,
                                           PropertyControl propControl) {
  return new (C) ObjCPropertyDecl(DC, L, Id, T);
}


//===----------------------------------------------------------------------===//
// ObjCPropertyImplDecl
//===----------------------------------------------------------------------===//

ObjCPropertyImplDecl *ObjCPropertyImplDecl::Create(ASTContext &C,
                                                   DeclContext *DC,
                                                   SourceLocation atLoc,
                                                   SourceLocation L,
                                                   ObjCPropertyDecl *property,
                                                   Kind PK,
                                                   ObjCIvarDecl *ivar) {
  return new (C) ObjCPropertyImplDecl(DC, atLoc, L, property, PK, ivar);
}