Add the clang library to the repo (with some of my changes, too).

1 files changed, 1373 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaPseudoObject.cpp b/clang/lib/Sema/SemaPseudoObject.cpp
new file mode 100644
index 0000000..0e66329
--- /dev/null
+++ b/clang/lib/Sema/SemaPseudoObject.cpp
@@ -0,0 +1,1373 @@
+//===--- SemaPseudoObject.cpp - Semantic Analysis for Pseudo-Objects ------===//
+//
+//                     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 expressions involving
+//  pseudo-object references.  Pseudo-objects are conceptual objects
+//  whose storage is entirely abstract and all accesses to which are
+//  translated through some sort of abstraction barrier.
+//
+//  For example, Objective-C objects can have "properties", either
+//  declared or undeclared.  A property may be accessed by writing
+//    expr.prop
+//  where 'expr' is an r-value of Objective-C pointer type and 'prop'
+//  is the name of the property.  If this expression is used in a context
+//  needing an r-value, it is treated as if it were a message-send
+//  of the associated 'getter' selector, typically:
+//    [expr prop]
+//  If it is used as the LHS of a simple assignment, it is treated
+//  as a message-send of the associated 'setter' selector, typically:
+//    [expr setProp: RHS]
+//  If it is used as the LHS of a compound assignment, or the operand
+//  of a unary increment or decrement, both are required;  for example,
+//  'expr.prop *= 100' would be translated to:
+//    [expr setProp: [expr prop] * 100]
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Sema/SemaInternal.h"
+#include "clang/Sema/Initialization.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/Lex/Preprocessor.h"
+
+using namespace clang;
+using namespace sema;
+
+namespace {
+  // Basically just a very focused copy of TreeTransform.
+  template <class T> struct Rebuilder {
+    Sema &S;
+    Rebuilder(Sema &S) : S(S) {}
+
+    T &getDerived() { return static_cast<T&>(*this); }
+
+    Expr *rebuild(Expr *e) {
+      // Fast path: nothing to look through.
+      if (typename T::specific_type *specific
+            = dyn_cast<typename T::specific_type>(e))
+        return getDerived().rebuildSpecific(specific);
+
+      // Otherwise, we should look through and rebuild anything that
+      // IgnoreParens would.
+
+      if (ParenExpr *parens = dyn_cast<ParenExpr>(e)) {
+        e = rebuild(parens->getSubExpr());
+        return new (S.Context) ParenExpr(parens->getLParen(),
+                                         parens->getRParen(),
+                                         e);
+      }
+
+      if (UnaryOperator *uop = dyn_cast<UnaryOperator>(e)) {
+        assert(uop->getOpcode() == UO_Extension);
+        e = rebuild(uop->getSubExpr());
+        return new (S.Context) UnaryOperator(e, uop->getOpcode(),
+                                             uop->getType(),
+                                             uop->getValueKind(),
+                                             uop->getObjectKind(),
+                                             uop->getOperatorLoc());
+      }
+
+      if (GenericSelectionExpr *gse = dyn_cast<GenericSelectionExpr>(e)) {
+        assert(!gse->isResultDependent());
+        unsigned resultIndex = gse->getResultIndex();
+        unsigned numAssocs = gse->getNumAssocs();
+
+        SmallVector<Expr*, 8> assocs(numAssocs);
+        SmallVector<TypeSourceInfo*, 8> assocTypes(numAssocs);
+
+        for (unsigned i = 0; i != numAssocs; ++i) {
+          Expr *assoc = gse->getAssocExpr(i);
+          if (i == resultIndex) assoc = rebuild(assoc);
+          assocs[i] = assoc;
+          assocTypes[i] = gse->getAssocTypeSourceInfo(i);
+        }
+
+        return new (S.Context) GenericSelectionExpr(S.Context,
+                                                    gse->getGenericLoc(),
+                                                    gse->getControllingExpr(),
+                                                    assocTypes.data(),
+                                                    assocs.data(),
+                                                    numAssocs,
+                                                    gse->getDefaultLoc(),
+                                                    gse->getRParenLoc(),
+                                      gse->containsUnexpandedParameterPack(),
+                                                    resultIndex);
+      }
+
+      llvm_unreachable("bad expression to rebuild!");
+    }
+  };
+
+  struct ObjCPropertyRefRebuilder : Rebuilder<ObjCPropertyRefRebuilder> {
+    Expr *NewBase;
+    ObjCPropertyRefRebuilder(Sema &S, Expr *newBase)
+      : Rebuilder<ObjCPropertyRefRebuilder>(S), NewBase(newBase) {}
+
+    typedef ObjCPropertyRefExpr specific_type;
+    Expr *rebuildSpecific(ObjCPropertyRefExpr *refExpr) {
+      // Fortunately, the constraint that we're rebuilding something
+      // with a base limits the number of cases here.
+      assert(refExpr->getBase());
+
+      if (refExpr->isExplicitProperty()) {
+        return new (S.Context)
+          ObjCPropertyRefExpr(refExpr->getExplicitProperty(),
+                              refExpr->getType(), refExpr->getValueKind(),
+                              refExpr->getObjectKind(), refExpr->getLocation(),
+                              NewBase);
+      }
+      return new (S.Context)
+        ObjCPropertyRefExpr(refExpr->getImplicitPropertyGetter(),
+                            refExpr->getImplicitPropertySetter(),
+                            refExpr->getType(), refExpr->getValueKind(),
+                            refExpr->getObjectKind(),refExpr->getLocation(),
+                            NewBase);
+    }
+  };
+
+  struct ObjCSubscriptRefRebuilder : Rebuilder<ObjCSubscriptRefRebuilder> {
+    Expr *NewBase;
+    Expr *NewKeyExpr;
+    ObjCSubscriptRefRebuilder(Sema &S, Expr *newBase, Expr *newKeyExpr)
+    : Rebuilder<ObjCSubscriptRefRebuilder>(S), 
+      NewBase(newBase), NewKeyExpr(newKeyExpr) {}
+    
+    typedef ObjCSubscriptRefExpr specific_type;
+    Expr *rebuildSpecific(ObjCSubscriptRefExpr *refExpr) {
+      assert(refExpr->getBaseExpr());
+      assert(refExpr->getKeyExpr());
+      
+      return new (S.Context)
+        ObjCSubscriptRefExpr(NewBase,
+                             NewKeyExpr,
+                             refExpr->getType(), refExpr->getValueKind(),
+                             refExpr->getObjectKind(),refExpr->getAtIndexMethodDecl(),
+                             refExpr->setAtIndexMethodDecl(),
+                             refExpr->getRBracket());
+    }
+  };
+  
+  class PseudoOpBuilder {
+  public:
+    Sema &S;
+    unsigned ResultIndex;
+    SourceLocation GenericLoc;
+    SmallVector<Expr *, 4> Semantics;
+
+    PseudoOpBuilder(Sema &S, SourceLocation genericLoc)
+      : S(S), ResultIndex(PseudoObjectExpr::NoResult),
+        GenericLoc(genericLoc) {}
+
+    virtual ~PseudoOpBuilder() {}
+
+    /// Add a normal semantic expression.
+    void addSemanticExpr(Expr *semantic) {
+      Semantics.push_back(semantic);
+    }
+
+    /// Add the 'result' semantic expression.
+    void addResultSemanticExpr(Expr *resultExpr) {
+      assert(ResultIndex == PseudoObjectExpr::NoResult);
+      ResultIndex = Semantics.size();
+      Semantics.push_back(resultExpr);
+    }
+
+    ExprResult buildRValueOperation(Expr *op);
+    ExprResult buildAssignmentOperation(Scope *Sc,
+                                        SourceLocation opLoc,
+                                        BinaryOperatorKind opcode,
+                                        Expr *LHS, Expr *RHS);
+    ExprResult buildIncDecOperation(Scope *Sc, SourceLocation opLoc,
+                                    UnaryOperatorKind opcode,
+                                    Expr *op);
+
+    ExprResult complete(Expr *syntacticForm);
+
+    OpaqueValueExpr *capture(Expr *op);
+    OpaqueValueExpr *captureValueAsResult(Expr *op);
+
+    void setResultToLastSemantic() {
+      assert(ResultIndex == PseudoObjectExpr::NoResult);
+      ResultIndex = Semantics.size() - 1;
+    }
+
+    /// Return true if assignments have a non-void result.
+    virtual bool assignmentsHaveResult() { return true; }
+
+    virtual Expr *rebuildAndCaptureObject(Expr *) = 0;
+    virtual ExprResult buildGet() = 0;
+    virtual ExprResult buildSet(Expr *, SourceLocation,
+                                bool captureSetValueAsResult) = 0;
+  };
+
+  /// A PseudoOpBuilder for Objective-C @properties.
+  class ObjCPropertyOpBuilder : public PseudoOpBuilder {
+    ObjCPropertyRefExpr *RefExpr;
+    ObjCPropertyRefExpr *SyntacticRefExpr;
+    OpaqueValueExpr *InstanceReceiver;
+    ObjCMethodDecl *Getter;
+
+    ObjCMethodDecl *Setter;
+    Selector SetterSelector;
+    Selector GetterSelector;
+
+  public:
+    ObjCPropertyOpBuilder(Sema &S, ObjCPropertyRefExpr *refExpr) :
+      PseudoOpBuilder(S, refExpr->getLocation()), RefExpr(refExpr),
+      SyntacticRefExpr(0), InstanceReceiver(0), Getter(0), Setter(0) {
+    }
+
+    ExprResult buildRValueOperation(Expr *op);
+    ExprResult buildAssignmentOperation(Scope *Sc,
+                                        SourceLocation opLoc,
+                                        BinaryOperatorKind opcode,
+                                        Expr *LHS, Expr *RHS);
+    ExprResult buildIncDecOperation(Scope *Sc, SourceLocation opLoc,
+                                    UnaryOperatorKind opcode,
+                                    Expr *op);
+
+    bool tryBuildGetOfReference(Expr *op, ExprResult &result);
+    bool findSetter();
+    bool findGetter();
+
+    Expr *rebuildAndCaptureObject(Expr *syntacticBase);
+    ExprResult buildGet();
+    ExprResult buildSet(Expr *op, SourceLocation, bool);
+  };
+
+ /// A PseudoOpBuilder for Objective-C array/dictionary indexing.
+ class ObjCSubscriptOpBuilder : public PseudoOpBuilder {
+   ObjCSubscriptRefExpr *RefExpr;
+   OpaqueValueExpr *InstanceBase;
+   OpaqueValueExpr *InstanceKey;
+   ObjCMethodDecl *AtIndexGetter;
+   Selector AtIndexGetterSelector;
+  
+   ObjCMethodDecl *AtIndexSetter;
+   Selector AtIndexSetterSelector;
+  
+ public:
+    ObjCSubscriptOpBuilder(Sema &S, ObjCSubscriptRefExpr *refExpr) :
+      PseudoOpBuilder(S, refExpr->getSourceRange().getBegin()), 
+      RefExpr(refExpr),
+    InstanceBase(0), InstanceKey(0), 
+    AtIndexGetter(0), AtIndexSetter(0) { }
+  
+   ExprResult buildRValueOperation(Expr *op);
+   ExprResult buildAssignmentOperation(Scope *Sc,
+                                       SourceLocation opLoc,
+                                       BinaryOperatorKind opcode,
+                                       Expr *LHS, Expr *RHS);
+   Expr *rebuildAndCaptureObject(Expr *syntacticBase);
+   
+   bool findAtIndexGetter();
+   bool findAtIndexSetter();
+  
+   ExprResult buildGet();
+   ExprResult buildSet(Expr *op, SourceLocation, bool);
+ };
+
+}
+
+/// Capture the given expression in an OpaqueValueExpr.
+OpaqueValueExpr *PseudoOpBuilder::capture(Expr *e) {
+  // Make a new OVE whose source is the given expression.
+  OpaqueValueExpr *captured = 
+    new (S.Context) OpaqueValueExpr(GenericLoc, e->getType(),
+                                    e->getValueKind(), e->getObjectKind(),
+                                    e);
+  
+  // Make sure we bind that in the semantics.
+  addSemanticExpr(captured);
+  return captured;
+}
+
+/// Capture the given expression as the result of this pseudo-object
+/// operation.  This routine is safe against expressions which may
+/// already be captured.
+///
+/// \param Returns the captured expression, which will be the
+///   same as the input if the input was already captured
+OpaqueValueExpr *PseudoOpBuilder::captureValueAsResult(Expr *e) {
+  assert(ResultIndex == PseudoObjectExpr::NoResult);
+
+  // If the expression hasn't already been captured, just capture it
+  // and set the new semantic 
+  if (!isa<OpaqueValueExpr>(e)) {
+    OpaqueValueExpr *cap = capture(e);
+    setResultToLastSemantic();
+    return cap;
+  }
+
+  // Otherwise, it must already be one of our semantic expressions;
+  // set ResultIndex to its index.
+  unsigned index = 0;
+  for (;; ++index) {
+    assert(index < Semantics.size() &&
+           "captured expression not found in semantics!");
+    if (e == Semantics[index]) break;
+  }
+  ResultIndex = index;
+  return cast<OpaqueValueExpr>(e);
+}
+
+/// The routine which creates the final PseudoObjectExpr.
+ExprResult PseudoOpBuilder::complete(Expr *syntactic) {
+  return PseudoObjectExpr::Create(S.Context, syntactic,
+                                  Semantics, ResultIndex);
+}
+
+/// The main skeleton for building an r-value operation.
+ExprResult PseudoOpBuilder::buildRValueOperation(Expr *op) {
+  Expr *syntacticBase = rebuildAndCaptureObject(op);
+
+  ExprResult getExpr = buildGet();
+  if (getExpr.isInvalid()) return ExprError();
+  addResultSemanticExpr(getExpr.take());
+
+  return complete(syntacticBase);
+}
+
+/// The basic skeleton for building a simple or compound
+/// assignment operation.
+ExprResult
+PseudoOpBuilder::buildAssignmentOperation(Scope *Sc, SourceLocation opcLoc,
+                                          BinaryOperatorKind opcode,
+                                          Expr *LHS, Expr *RHS) {
+  assert(BinaryOperator::isAssignmentOp(opcode));
+
+  Expr *syntacticLHS = rebuildAndCaptureObject(LHS);
+  OpaqueValueExpr *capturedRHS = capture(RHS);
+
+  Expr *syntactic;
+
+  ExprResult result;
+  if (opcode == BO_Assign) {
+    result = capturedRHS;
+    syntactic = new (S.Context) BinaryOperator(syntacticLHS, capturedRHS,
+                                               opcode, capturedRHS->getType(),
+                                               capturedRHS->getValueKind(),
+                                               OK_Ordinary, opcLoc);
+  } else {
+    ExprResult opLHS = buildGet();
+    if (opLHS.isInvalid()) return ExprError();
+
+    // Build an ordinary, non-compound operation.
+    BinaryOperatorKind nonCompound =
+      BinaryOperator::getOpForCompoundAssignment(opcode);
+    result = S.BuildBinOp(Sc, opcLoc, nonCompound,
+                          opLHS.take(), capturedRHS);
+    if (result.isInvalid()) return ExprError();
+
+    syntactic =
+      new (S.Context) CompoundAssignOperator(syntacticLHS, capturedRHS, opcode,
+                                             result.get()->getType(),
+                                             result.get()->getValueKind(),
+                                             OK_Ordinary,
+                                             opLHS.get()->getType(),
+                                             result.get()->getType(),
+                                             opcLoc);
+  }
+
+  // The result of the assignment, if not void, is the value set into
+  // the l-value.
+  result = buildSet(result.take(), opcLoc, assignmentsHaveResult());
+  if (result.isInvalid()) return ExprError();
+  addSemanticExpr(result.take());
+
+  return complete(syntactic);
+}
+
+/// The basic skeleton for building an increment or decrement
+/// operation.
+ExprResult
+PseudoOpBuilder::buildIncDecOperation(Scope *Sc, SourceLocation opcLoc,
+                                      UnaryOperatorKind opcode,
+                                      Expr *op) {
+  assert(UnaryOperator::isIncrementDecrementOp(opcode));
+
+  Expr *syntacticOp = rebuildAndCaptureObject(op);
+
+  // Load the value.
+  ExprResult result = buildGet();
+  if (result.isInvalid()) return ExprError();
+
+  QualType resultType = result.get()->getType();
+
+  // That's the postfix result.
+  if (UnaryOperator::isPostfix(opcode) && assignmentsHaveResult()) {
+    result = capture(result.take());
+    setResultToLastSemantic();
+  }
+
+  // Add or subtract a literal 1.
+  llvm::APInt oneV(S.Context.getTypeSize(S.Context.IntTy), 1);
+  Expr *one = IntegerLiteral::Create(S.Context, oneV, S.Context.IntTy,
+                                     GenericLoc);
+
+  if (UnaryOperator::isIncrementOp(opcode)) {
+    result = S.BuildBinOp(Sc, opcLoc, BO_Add, result.take(), one);
+  } else {
+    result = S.BuildBinOp(Sc, opcLoc, BO_Sub, result.take(), one);
+  }
+  if (result.isInvalid()) return ExprError();
+
+  // Store that back into the result.  The value stored is the result
+  // of a prefix operation.
+  result = buildSet(result.take(), opcLoc,
+             UnaryOperator::isPrefix(opcode) && assignmentsHaveResult());
+  if (result.isInvalid()) return ExprError();
+  addSemanticExpr(result.take());
+
+  UnaryOperator *syntactic =
+    new (S.Context) UnaryOperator(syntacticOp, opcode, resultType,
+                                  VK_LValue, OK_Ordinary, opcLoc);
+  return complete(syntactic);
+}
+
+
+//===----------------------------------------------------------------------===//
+//  Objective-C @property and implicit property references
+//===----------------------------------------------------------------------===//
+
+/// Look up a method in the receiver type of an Objective-C property
+/// reference.
+static ObjCMethodDecl *LookupMethodInReceiverType(Sema &S, Selector sel,
+                                            const ObjCPropertyRefExpr *PRE) {
+  if (PRE->isObjectReceiver()) {
+    const ObjCObjectPointerType *PT =
+      PRE->getBase()->getType()->castAs<ObjCObjectPointerType>();
+
+    // Special case for 'self' in class method implementations.
+    if (PT->isObjCClassType() &&
+        S.isSelfExpr(const_cast<Expr*>(PRE->getBase()))) {
+      // This cast is safe because isSelfExpr is only true within
+      // methods.
+      ObjCMethodDecl *method =
+        cast<ObjCMethodDecl>(S.CurContext->getNonClosureAncestor());
+      return S.LookupMethodInObjectType(sel,
+                 S.Context.getObjCInterfaceType(method->getClassInterface()),
+                                        /*instance*/ false);
+    }
+
+    return S.LookupMethodInObjectType(sel, PT->getPointeeType(), true);
+  }
+
+  if (PRE->isSuperReceiver()) {
+    if (const ObjCObjectPointerType *PT =
+        PRE->getSuperReceiverType()->getAs<ObjCObjectPointerType>())
+      return S.LookupMethodInObjectType(sel, PT->getPointeeType(), true);
+
+    return S.LookupMethodInObjectType(sel, PRE->getSuperReceiverType(), false);
+  }
+
+  assert(PRE->isClassReceiver() && "Invalid expression");
+  QualType IT = S.Context.getObjCInterfaceType(PRE->getClassReceiver());
+  return S.LookupMethodInObjectType(sel, IT, false);
+}
+
+bool ObjCPropertyOpBuilder::findGetter() {
+  if (Getter) return true;
+
+  // For implicit properties, just trust the lookup we already did.
+  if (RefExpr->isImplicitProperty()) {
+    if ((Getter = RefExpr->getImplicitPropertyGetter())) {
+      GetterSelector = Getter->getSelector();
+      return true;
+    }
+    else {
+      // Must build the getter selector the hard way.
+      ObjCMethodDecl *setter = RefExpr->getImplicitPropertySetter();
+      assert(setter && "both setter and getter are null - cannot happen");
+      IdentifierInfo *setterName = 
+        setter->getSelector().getIdentifierInfoForSlot(0);
+      const char *compStr = setterName->getNameStart();
+      compStr += 3;
+      IdentifierInfo *getterName = &S.Context.Idents.get(compStr);
+      GetterSelector = 
+        S.PP.getSelectorTable().getNullarySelector(getterName);
+      return false;
+
+    }
+  }
+
+  ObjCPropertyDecl *prop = RefExpr->getExplicitProperty();
+  Getter = LookupMethodInReceiverType(S, prop->getGetterName(), RefExpr);
+  return (Getter != 0);
+}
+
+/// Try to find the most accurate setter declaration for the property
+/// reference.
+///
+/// \return true if a setter was found, in which case Setter 
+bool ObjCPropertyOpBuilder::findSetter() {
+  // For implicit properties, just trust the lookup we already did.
+  if (RefExpr->isImplicitProperty()) {
+    if (ObjCMethodDecl *setter = RefExpr->getImplicitPropertySetter()) {
+      Setter = setter;
+      SetterSelector = setter->getSelector();
+      return true;
+    } else {
+      IdentifierInfo *getterName =
+        RefExpr->getImplicitPropertyGetter()->getSelector()
+          .getIdentifierInfoForSlot(0);
+      SetterSelector =
+        SelectorTable::constructSetterName(S.PP.getIdentifierTable(),
+                                           S.PP.getSelectorTable(),
+                                           getterName);
+      return false;
+    }
+  }
+
+  // For explicit properties, this is more involved.
+  ObjCPropertyDecl *prop = RefExpr->getExplicitProperty();
+  SetterSelector = prop->getSetterName();
+
+  // Do a normal method lookup first.
+  if (ObjCMethodDecl *setter =
+        LookupMethodInReceiverType(S, SetterSelector, RefExpr)) {
+    Setter = setter;
+    return true;
+  }
+
+  // That can fail in the somewhat crazy situation that we're
+  // type-checking a message send within the @interface declaration
+  // that declared the @property.  But it's not clear that that's
+  // valuable to support.
+
+  return false;
+}
+
+/// Capture the base object of an Objective-C property expression.
+Expr *ObjCPropertyOpBuilder::rebuildAndCaptureObject(Expr *syntacticBase) {
+  assert(InstanceReceiver == 0);
+
+  // If we have a base, capture it in an OVE and rebuild the syntactic
+  // form to use the OVE as its base.
+  if (RefExpr->isObjectReceiver()) {
+    InstanceReceiver = capture(RefExpr->getBase());
+
+    syntacticBase =
+      ObjCPropertyRefRebuilder(S, InstanceReceiver).rebuild(syntacticBase);
+  }
+
+  if (ObjCPropertyRefExpr *
+        refE = dyn_cast<ObjCPropertyRefExpr>(syntacticBase->IgnoreParens()))
+    SyntacticRefExpr = refE;
+
+  return syntacticBase;
+}
+
+/// Load from an Objective-C property reference.
+ExprResult ObjCPropertyOpBuilder::buildGet() {
+  findGetter();
+  assert(Getter);
+
+  if (SyntacticRefExpr)
+    SyntacticRefExpr->setIsMessagingGetter();
+
+  QualType receiverType;
+  if (RefExpr->isClassReceiver()) {
+    receiverType = S.Context.getObjCInterfaceType(RefExpr->getClassReceiver());
+  } else if (RefExpr->isSuperReceiver()) {
+    receiverType = RefExpr->getSuperReceiverType();
+  } else {
+    assert(InstanceReceiver);
+    receiverType = InstanceReceiver->getType();
+  }
+
+  // Build a message-send.
+  ExprResult msg;
+  if (Getter->isInstanceMethod() || RefExpr->isObjectReceiver()) {
+    assert(InstanceReceiver || RefExpr->isSuperReceiver());
+    msg = S.BuildInstanceMessageImplicit(InstanceReceiver, receiverType,
+                                         GenericLoc, Getter->getSelector(),
+                                         Getter, MultiExprArg());
+  } else {
+    msg = S.BuildClassMessageImplicit(receiverType, RefExpr->isSuperReceiver(),
+                                      GenericLoc,
+                                      Getter->getSelector(), Getter,
+                                      MultiExprArg());
+  }
+  return msg;
+}
+
+/// Store to an Objective-C property reference.
+///
+/// \param bindSetValueAsResult - If true, capture the actual
+///   value being set as the value of the property operation.
+ExprResult ObjCPropertyOpBuilder::buildSet(Expr *op, SourceLocation opcLoc,
+                                           bool captureSetValueAsResult) {
+  bool hasSetter = findSetter();
+  assert(hasSetter); (void) hasSetter;
+
+  if (SyntacticRefExpr)
+    SyntacticRefExpr->setIsMessagingSetter();
+
+  QualType receiverType;
+  if (RefExpr->isClassReceiver()) {
+    receiverType = S.Context.getObjCInterfaceType(RefExpr->getClassReceiver());
+  } else if (RefExpr->isSuperReceiver()) {
+    receiverType = RefExpr->getSuperReceiverType();
+  } else {
+    assert(InstanceReceiver);
+    receiverType = InstanceReceiver->getType();
+  }
+
+  // Use assignment constraints when possible; they give us better
+  // diagnostics.  "When possible" basically means anything except a
+  // C++ class type.
+  if (!S.getLangOpts().CPlusPlus || !op->getType()->isRecordType()) {
+    QualType paramType = (*Setter->param_begin())->getType();
+    if (!S.getLangOpts().CPlusPlus || !paramType->isRecordType()) {
+      ExprResult opResult = op;
+      Sema::AssignConvertType assignResult
+        = S.CheckSingleAssignmentConstraints(paramType, opResult);
+      if (S.DiagnoseAssignmentResult(assignResult, opcLoc, paramType,
+                                     op->getType(), opResult.get(),
+                                     Sema::AA_Assigning))
+        return ExprError();
+
+      op = opResult.take();
+      assert(op && "successful assignment left argument invalid?");
+    }
+  }
+
+  // Arguments.
+  Expr *args[] = { op };
+
+  // Build a message-send.
+  ExprResult msg;
+  if (Setter->isInstanceMethod() || RefExpr->isObjectReceiver()) {
+    msg = S.BuildInstanceMessageImplicit(InstanceReceiver, receiverType,
+                                         GenericLoc, SetterSelector, Setter,
+                                         MultiExprArg(args, 1));
+  } else {
+    msg = S.BuildClassMessageImplicit(receiverType, RefExpr->isSuperReceiver(),
+                                      GenericLoc,
+                                      SetterSelector, Setter,
+                                      MultiExprArg(args, 1));
+  }
+
+  if (!msg.isInvalid() && captureSetValueAsResult) {
+    ObjCMessageExpr *msgExpr =
+      cast<ObjCMessageExpr>(msg.get()->IgnoreImplicit());
+    Expr *arg = msgExpr->getArg(0);
+    msgExpr->setArg(0, captureValueAsResult(arg));
+  }
+
+  return msg;
+}
+
+/// @property-specific behavior for doing lvalue-to-rvalue conversion.
+ExprResult ObjCPropertyOpBuilder::buildRValueOperation(Expr *op) {
+  // Explicit properties always have getters, but implicit ones don't.
+  // Check that before proceeding.
+  if (RefExpr->isImplicitProperty() &&
+      !RefExpr->getImplicitPropertyGetter()) {
+    S.Diag(RefExpr->getLocation(), diag::err_getter_not_found)
+      << RefExpr->getBase()->getType();
+    return ExprError();
+  }
+
+  ExprResult result = PseudoOpBuilder::buildRValueOperation(op);
+  if (result.isInvalid()) return ExprError();
+
+  if (RefExpr->isExplicitProperty() && !Getter->hasRelatedResultType())
+    S.DiagnosePropertyAccessorMismatch(RefExpr->getExplicitProperty(),
+                                       Getter, RefExpr->getLocation());
+
+  // As a special case, if the method returns 'id', try to get
+  // a better type from the property.
+  if (RefExpr->isExplicitProperty() && result.get()->isRValue() &&
+      result.get()->getType()->isObjCIdType()) {
+    QualType propType = RefExpr->getExplicitProperty()->getType();
+    if (const ObjCObjectPointerType *ptr
+          = propType->getAs<ObjCObjectPointerType>()) {
+      if (!ptr->isObjCIdType())
+        result = S.ImpCastExprToType(result.get(), propType, CK_BitCast);
+    }
+  }
+
+  return result;
+}
+
+/// Try to build this as a call to a getter that returns a reference.
+///
+/// \return true if it was possible, whether or not it actually
+///   succeeded
+bool ObjCPropertyOpBuilder::tryBuildGetOfReference(Expr *op,
+                                                   ExprResult &result) {
+  if (!S.getLangOpts().CPlusPlus) return false;
+
+  findGetter();
+  assert(Getter && "property has no setter and no getter!");
+
+  // Only do this if the getter returns an l-value reference type.
+  QualType resultType = Getter->getResultType();
+  if (!resultType->isLValueReferenceType()) return false;
+
+  result = buildRValueOperation(op);
+  return true;
+}
+
+/// @property-specific behavior for doing assignments.
+ExprResult
+ObjCPropertyOpBuilder::buildAssignmentOperation(Scope *Sc,
+                                                SourceLocation opcLoc,
+                                                BinaryOperatorKind opcode,
+                                                Expr *LHS, Expr *RHS) {
+  assert(BinaryOperator::isAssignmentOp(opcode));
+
+  // If there's no setter, we have no choice but to try to assign to
+  // the result of the getter.
+  if (!findSetter()) {
+    ExprResult result;
+    if (tryBuildGetOfReference(LHS, result)) {
+      if (result.isInvalid()) return ExprError();
+      return S.BuildBinOp(Sc, opcLoc, opcode, result.take(), RHS);
+    }
+
+    // Otherwise, it's an error.
+    S.Diag(opcLoc, diag::err_nosetter_property_assignment)
+      << unsigned(RefExpr->isImplicitProperty())
+      << SetterSelector
+      << LHS->getSourceRange() << RHS->getSourceRange();
+    return ExprError();
+  }
+
+  // If there is a setter, we definitely want to use it.
+
+  // Verify that we can do a compound assignment.
+  if (opcode != BO_Assign && !findGetter()) {
+    S.Diag(opcLoc, diag::err_nogetter_property_compound_assignment)
+      << LHS->getSourceRange() << RHS->getSourceRange();
+    return ExprError();
+  }
+
+  ExprResult result =
+    PseudoOpBuilder::buildAssignmentOperation(Sc, opcLoc, opcode, LHS, RHS);
+  if (result.isInvalid()) return ExprError();
+
+  // Various warnings about property assignments in ARC.
+  if (S.getLangOpts().ObjCAutoRefCount && InstanceReceiver) {
+    S.checkRetainCycles(InstanceReceiver->getSourceExpr(), RHS);
+    S.checkUnsafeExprAssigns(opcLoc, LHS, RHS);
+  }
+
+  return result;
+}
+
+/// @property-specific behavior for doing increments and decrements.
+ExprResult
+ObjCPropertyOpBuilder::buildIncDecOperation(Scope *Sc, SourceLocation opcLoc,
+                                            UnaryOperatorKind opcode,
+                                            Expr *op) {
+  // If there's no setter, we have no choice but to try to assign to
+  // the result of the getter.
+  if (!findSetter()) {
+    ExprResult result;
+    if (tryBuildGetOfReference(op, result)) {
+      if (result.isInvalid()) return ExprError();
+      return S.BuildUnaryOp(Sc, opcLoc, opcode, result.take());
+    }
+
+    // Otherwise, it's an error.
+    S.Diag(opcLoc, diag::err_nosetter_property_incdec)
+      << unsigned(RefExpr->isImplicitProperty())
+      << unsigned(UnaryOperator::isDecrementOp(opcode))
+      << SetterSelector
+      << op->getSourceRange();
+    return ExprError();
+  }
+
+  // If there is a setter, we definitely want to use it.
+
+  // We also need a getter.
+  if (!findGetter()) {
+    assert(RefExpr->isImplicitProperty());
+    S.Diag(opcLoc, diag::err_nogetter_property_incdec)
+      << unsigned(UnaryOperator::isDecrementOp(opcode))
+      << GetterSelector
+      << op->getSourceRange();
+    return ExprError();
+  }
+
+  return PseudoOpBuilder::buildIncDecOperation(Sc, opcLoc, opcode, op);
+}
+
+// ObjCSubscript build stuff.
+//
+
+/// objective-c subscripting-specific behavior for doing lvalue-to-rvalue 
+/// conversion.
+/// FIXME. Remove this routine if it is proven that no additional 
+/// specifity is needed.
+ExprResult ObjCSubscriptOpBuilder::buildRValueOperation(Expr *op) {
+  ExprResult result = PseudoOpBuilder::buildRValueOperation(op);
+  if (result.isInvalid()) return ExprError();
+  return result;
+}
+
+/// objective-c subscripting-specific  behavior for doing assignments.
+ExprResult
+ObjCSubscriptOpBuilder::buildAssignmentOperation(Scope *Sc,
+                                                SourceLocation opcLoc,
+                                                BinaryOperatorKind opcode,
+                                                Expr *LHS, Expr *RHS) {
+  assert(BinaryOperator::isAssignmentOp(opcode));
+  // There must be a method to do the Index'ed assignment.
+  if (!findAtIndexSetter())
+    return ExprError();
+  
+  // Verify that we can do a compound assignment.
+  if (opcode != BO_Assign && !findAtIndexGetter())
+    return ExprError();
+  
+  ExprResult result =
+  PseudoOpBuilder::buildAssignmentOperation(Sc, opcLoc, opcode, LHS, RHS);
+  if (result.isInvalid()) return ExprError();
+  
+  // Various warnings about objc Index'ed assignments in ARC.
+  if (S.getLangOpts().ObjCAutoRefCount && InstanceBase) {
+    S.checkRetainCycles(InstanceBase->getSourceExpr(), RHS);
+    S.checkUnsafeExprAssigns(opcLoc, LHS, RHS);
+  }
+  
+  return result;
+}
+
+/// Capture the base object of an Objective-C Index'ed expression.
+Expr *ObjCSubscriptOpBuilder::rebuildAndCaptureObject(Expr *syntacticBase) {
+  assert(InstanceBase == 0);
+  
+  // Capture base expression in an OVE and rebuild the syntactic
+  // form to use the OVE as its base expression.
+  InstanceBase = capture(RefExpr->getBaseExpr());
+  InstanceKey = capture(RefExpr->getKeyExpr());
+    
+  syntacticBase =
+    ObjCSubscriptRefRebuilder(S, InstanceBase, 
+                              InstanceKey).rebuild(syntacticBase);
+  
+  return syntacticBase;
+}
+
+/// CheckSubscriptingKind - This routine decide what type 
+/// of indexing represented by "FromE" is being done.
+Sema::ObjCSubscriptKind 
+  Sema::CheckSubscriptingKind(Expr *FromE) {
+  // If the expression already has integral or enumeration type, we're golden.
+  QualType T = FromE->getType();
+  if (T->isIntegralOrEnumerationType())
+    return OS_Array;
+  
+  // If we don't have a class type in C++, there's no way we can get an
+  // expression of integral or enumeration type.
+  const RecordType *RecordTy = T->getAs<RecordType>();
+  if (!RecordTy && T->isObjCObjectPointerType())
+    // All other scalar cases are assumed to be dictionary indexing which
+    // caller handles, with diagnostics if needed.
+    return OS_Dictionary;
+  if (!getLangOpts().CPlusPlus || 
+      !RecordTy || RecordTy->isIncompleteType()) {
+    // No indexing can be done. Issue diagnostics and quit.
+    const Expr *IndexExpr = FromE->IgnoreParenImpCasts();
+    if (isa<StringLiteral>(IndexExpr))
+      Diag(FromE->getExprLoc(), diag::err_objc_subscript_pointer)
+        << T << FixItHint::CreateInsertion(FromE->getExprLoc(), "@");
+    else
+      Diag(FromE->getExprLoc(), diag::err_objc_subscript_type_conversion)
+        << T;
+    return OS_Error;
+  }
+  
+  // We must have a complete class type.
+  if (RequireCompleteType(FromE->getExprLoc(), T, 
+                          PDiag(diag::err_objc_index_incomplete_class_type)
+                          << FromE->getSourceRange()))
+    return OS_Error;
+  
+  // Look for a conversion to an integral, enumeration type, or
+  // objective-C pointer type.
+  UnresolvedSet<4> ViableConversions;
+  UnresolvedSet<4> ExplicitConversions;
+  const UnresolvedSetImpl *Conversions
+    = cast<CXXRecordDecl>(RecordTy->getDecl())->getVisibleConversionFunctions();
+  
+  int NoIntegrals=0, NoObjCIdPointers=0;
+  SmallVector<CXXConversionDecl *, 4> ConversionDecls;
+    
+  for (UnresolvedSetImpl::iterator I = Conversions->begin(),
+       E = Conversions->end();
+       I != E;
+       ++I) {
+    if (CXXConversionDecl *Conversion
+        = dyn_cast<CXXConversionDecl>((*I)->getUnderlyingDecl())) {
+      QualType CT = Conversion->getConversionType().getNonReferenceType();
+      if (CT->isIntegralOrEnumerationType()) {
+        ++NoIntegrals;
+        ConversionDecls.push_back(Conversion);
+      }
+      else if (CT->isObjCIdType() ||CT->isBlockPointerType()) {
+        ++NoObjCIdPointers;
+        ConversionDecls.push_back(Conversion);
+      }
+    }
+  }
+  if (NoIntegrals ==1 && NoObjCIdPointers == 0)
+    return OS_Array;
+  if (NoIntegrals == 0 && NoObjCIdPointers == 1)
+    return OS_Dictionary;
+  if (NoIntegrals == 0 && NoObjCIdPointers == 0) {
+    // No conversion function was found. Issue diagnostic and return.
+    Diag(FromE->getExprLoc(), diag::err_objc_subscript_type_conversion)
+      << FromE->getType();
+    return OS_Error;
+  }
+  Diag(FromE->getExprLoc(), diag::err_objc_multiple_subscript_type_conversion)
+      << FromE->getType();
+  for (unsigned int i = 0; i < ConversionDecls.size(); i++)
+    Diag(ConversionDecls[i]->getLocation(), diag::not_conv_function_declared_at);
+    
+  return OS_Error;
+}
+
+bool ObjCSubscriptOpBuilder::findAtIndexGetter() {
+  if (AtIndexGetter)
+    return true;
+  
+  Expr *BaseExpr = RefExpr->getBaseExpr();
+  QualType BaseT = BaseExpr->getType();
+  
+  QualType ResultType;
+  if (const ObjCObjectPointerType *PTy =
+      BaseT->getAs<ObjCObjectPointerType>()) {
+    ResultType = PTy->getPointeeType();
+    if (const ObjCObjectType *iQFaceTy = 
+        ResultType->getAsObjCQualifiedInterfaceType())
+      ResultType = iQFaceTy->getBaseType();
+  }
+  Sema::ObjCSubscriptKind Res = 
+    S.CheckSubscriptingKind(RefExpr->getKeyExpr());
+  if (Res == Sema::OS_Error)
+    return false;
+  bool arrayRef = (Res == Sema::OS_Array);
+  
+  if (ResultType.isNull()) {
+    S.Diag(BaseExpr->getExprLoc(), diag::err_objc_subscript_base_type)
+      << BaseExpr->getType() << arrayRef;
+    return false;
+  }
+  if (!arrayRef) {
+    // dictionary subscripting.
+    // - (id)objectForKeyedSubscript:(id)key;
+    IdentifierInfo *KeyIdents[] = {
+      &S.Context.Idents.get("objectForKeyedSubscript")  
+    };
+    AtIndexGetterSelector = S.Context.Selectors.getSelector(1, KeyIdents);
+  }
+  else {
+    // - (id)objectAtIndexedSubscript:(size_t)index;
+    IdentifierInfo *KeyIdents[] = {
+      &S.Context.Idents.get("objectAtIndexedSubscript")  
+    };
+  
+    AtIndexGetterSelector = S.Context.Selectors.getSelector(1, KeyIdents);
+  }
+  
+  AtIndexGetter = S.LookupMethodInObjectType(AtIndexGetterSelector, ResultType, 
+                                             true /*instance*/);
+  bool receiverIdType = (BaseT->isObjCIdType() ||
+                         BaseT->isObjCQualifiedIdType());
+  
+  if (!AtIndexGetter && S.getLangOpts().DebuggerObjCLiteral) {
+    AtIndexGetter = ObjCMethodDecl::Create(S.Context, SourceLocation(), 
+                           SourceLocation(), AtIndexGetterSelector,
+                           S.Context.getObjCIdType() /*ReturnType*/,
+                           0 /*TypeSourceInfo */,
+                           S.Context.getTranslationUnitDecl(),
+                           true /*Instance*/, false/*isVariadic*/,
+                           /*isSynthesized=*/false,
+                           /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
+                           ObjCMethodDecl::Required,
+                           false);
+    ParmVarDecl *Argument = ParmVarDecl::Create(S.Context, AtIndexGetter,
+                                                SourceLocation(), SourceLocation(),
+                                                arrayRef ? &S.Context.Idents.get("index")
+                                                         : &S.Context.Idents.get("key"),
+                                                arrayRef ? S.Context.UnsignedLongTy
+                                                         : S.Context.getObjCIdType(),
+                                                /*TInfo=*/0,
+                                                SC_None,
+                                                SC_None,
+                                                0);
+    AtIndexGetter->setMethodParams(S.Context, Argument, 
+                                   ArrayRef<SourceLocation>());
+  }
+
+  if (!AtIndexGetter) {
+    if (!receiverIdType) {
+      S.Diag(BaseExpr->getExprLoc(), diag::err_objc_subscript_method_not_found)
+      << BaseExpr->getType() << 0 << arrayRef;
+      return false;
+    }
+    AtIndexGetter = 
+      S.LookupInstanceMethodInGlobalPool(AtIndexGetterSelector, 
+                                         RefExpr->getSourceRange(), 
+                                         true, false);
+  }
+  
+  if (AtIndexGetter) {
+    QualType T = AtIndexGetter->param_begin()[0]->getType();
+    if ((arrayRef && !T->isIntegralOrEnumerationType()) ||
+        (!arrayRef && !T->isObjCObjectPointerType())) {
+      S.Diag(RefExpr->getKeyExpr()->getExprLoc(), 
+             arrayRef ? diag::err_objc_subscript_index_type
+                      : diag::err_objc_subscript_key_type) << T;
+      S.Diag(AtIndexGetter->param_begin()[0]->getLocation(), 
+             diag::note_parameter_type) << T;
+      return false;
+    }
+    QualType R = AtIndexGetter->getResultType();
+    if (!R->isObjCObjectPointerType()) {
+      S.Diag(RefExpr->getKeyExpr()->getExprLoc(),
+             diag::err_objc_indexing_method_result_type) << R << arrayRef;
+      S.Diag(AtIndexGetter->getLocation(), diag::note_method_declared_at) <<
+        AtIndexGetter->getDeclName();
+    }
+  }
+  return true;
+}
+
+bool ObjCSubscriptOpBuilder::findAtIndexSetter() {
+  if (AtIndexSetter)
+    return true;
+  
+  Expr *BaseExpr = RefExpr->getBaseExpr();
+  QualType BaseT = BaseExpr->getType();
+  
+  QualType ResultType;
+  if (const ObjCObjectPointerType *PTy =
+      BaseT->getAs<ObjCObjectPointerType>()) {
+    ResultType = PTy->getPointeeType();
+    if (const ObjCObjectType *iQFaceTy = 
+        ResultType->getAsObjCQualifiedInterfaceType())
+      ResultType = iQFaceTy->getBaseType();
+  }
+  
+  Sema::ObjCSubscriptKind Res = 
+    S.CheckSubscriptingKind(RefExpr->getKeyExpr());
+  if (Res == Sema::OS_Error)
+    return false;
+  bool arrayRef = (Res == Sema::OS_Array);
+  
+  if (ResultType.isNull()) {
+    S.Diag(BaseExpr->getExprLoc(), diag::err_objc_subscript_base_type)
+      << BaseExpr->getType() << arrayRef;
+    return false;
+  }
+  
+  if (!arrayRef) {
+    // dictionary subscripting.
+    // - (void)setObject:(id)object forKeyedSubscript:(id)key;
+    IdentifierInfo *KeyIdents[] = {
+      &S.Context.Idents.get("setObject"),
+      &S.Context.Idents.get("forKeyedSubscript")
+    };
+    AtIndexSetterSelector = S.Context.Selectors.getSelector(2, KeyIdents);
+  }
+  else {
+    // - (void)setObject:(id)object atIndexedSubscript:(NSInteger)index;
+    IdentifierInfo *KeyIdents[] = {
+      &S.Context.Idents.get("setObject"),
+      &S.Context.Idents.get("atIndexedSubscript")
+    };
+    AtIndexSetterSelector = S.Context.Selectors.getSelector(2, KeyIdents);
+  }
+  AtIndexSetter = S.LookupMethodInObjectType(AtIndexSetterSelector, ResultType, 
+                                             true /*instance*/);
+  
+  bool receiverIdType = (BaseT->isObjCIdType() ||
+                         BaseT->isObjCQualifiedIdType());
+
+  if (!AtIndexSetter && S.getLangOpts().DebuggerObjCLiteral) {
+    TypeSourceInfo *ResultTInfo = 0;
+    QualType ReturnType = S.Context.VoidTy;
+    AtIndexSetter = ObjCMethodDecl::Create(S.Context, SourceLocation(),
+                           SourceLocation(), AtIndexSetterSelector,
+                           ReturnType,
+                           ResultTInfo,
+                           S.Context.getTranslationUnitDecl(),
+                           true /*Instance*/, false/*isVariadic*/,
+                           /*isSynthesized=*/false,
+                           /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
+                           ObjCMethodDecl::Required,
+                           false); 
+    SmallVector<ParmVarDecl *, 2> Params;
+    ParmVarDecl *object = ParmVarDecl::Create(S.Context, AtIndexSetter,
+                                                SourceLocation(), SourceLocation(),
+                                                &S.Context.Idents.get("object"),
+                                                S.Context.getObjCIdType(),
+                                                /*TInfo=*/0,
+                                                SC_None,
+                                                SC_None,
+                                                0);
+    Params.push_back(object);
+    ParmVarDecl *key = ParmVarDecl::Create(S.Context, AtIndexSetter,
+                                                SourceLocation(), SourceLocation(),
+                                                arrayRef ?  &S.Context.Idents.get("index")
+                                                         :  &S.Context.Idents.get("key"),
+                                                arrayRef ? S.Context.UnsignedLongTy
+                                                         : S.Context.getObjCIdType(),
+                                                /*TInfo=*/0,
+                                                SC_None,
+                                                SC_None,
+                                                0);
+    Params.push_back(key);
+    AtIndexSetter->setMethodParams(S.Context, Params, ArrayRef<SourceLocation>());
+  }
+  
+  if (!AtIndexSetter) {
+    if (!receiverIdType) {
+      S.Diag(BaseExpr->getExprLoc(), 
+             diag::err_objc_subscript_method_not_found)
+      << BaseExpr->getType() << 1 << arrayRef;
+      return false;
+    }
+    AtIndexSetter = 
+      S.LookupInstanceMethodInGlobalPool(AtIndexSetterSelector, 
+                                         RefExpr->getSourceRange(), 
+                                         true, false);
+  }
+  
+  bool err = false;
+  if (AtIndexSetter && arrayRef) {
+    QualType T = AtIndexSetter->param_begin()[1]->getType();
+    if (!T->isIntegralOrEnumerationType()) {
+      S.Diag(RefExpr->getKeyExpr()->getExprLoc(), 
+             diag::err_objc_subscript_index_type) << T;
+      S.Diag(AtIndexSetter->param_begin()[1]->getLocation(), 
+             diag::note_parameter_type) << T;
+      err = true;
+    }
+    T = AtIndexSetter->param_begin()[0]->getType();
+    if (!T->isObjCObjectPointerType()) {
+      S.Diag(RefExpr->getBaseExpr()->getExprLoc(), 
+             diag::err_objc_subscript_object_type) << T << arrayRef;
+      S.Diag(AtIndexSetter->param_begin()[0]->getLocation(), 
+             diag::note_parameter_type) << T;
+      err = true;
+    }
+  }
+  else if (AtIndexSetter && !arrayRef)
+    for (unsigned i=0; i <2; i++) {
+      QualType T = AtIndexSetter->param_begin()[i]->getType();
+      if (!T->isObjCObjectPointerType()) {
+        if (i == 1)
+          S.Diag(RefExpr->getKeyExpr()->getExprLoc(),
+                 diag::err_objc_subscript_key_type) << T;
+        else
+          S.Diag(RefExpr->getBaseExpr()->getExprLoc(),
+                 diag::err_objc_subscript_dic_object_type) << T;
+        S.Diag(AtIndexSetter->param_begin()[i]->getLocation(), 
+               diag::note_parameter_type) << T;
+        err = true;
+      }
+    }
+
+  return !err;
+}
+
+// Get the object at "Index" position in the container.
+// [BaseExpr objectAtIndexedSubscript : IndexExpr];
+ExprResult ObjCSubscriptOpBuilder::buildGet() {
+  if (!findAtIndexGetter())
+    return ExprError();
+  
+  QualType receiverType = InstanceBase->getType();
+    
+  // Build a message-send.
+  ExprResult msg;
+  Expr *Index = InstanceKey;
+  
+  // Arguments.
+  Expr *args[] = { Index };
+  assert(InstanceBase);
+  msg = S.BuildInstanceMessageImplicit(InstanceBase, receiverType,
+                                       GenericLoc,
+                                       AtIndexGetterSelector, AtIndexGetter,
+                                       MultiExprArg(args, 1));
+  return msg;
+}
+
+/// Store into the container the "op" object at "Index"'ed location
+/// by building this messaging expression:
+/// - (void)setObject:(id)object atIndexedSubscript:(NSInteger)index;
+/// \param bindSetValueAsResult - If true, capture the actual
+///   value being set as the value of the property operation.
+ExprResult ObjCSubscriptOpBuilder::buildSet(Expr *op, SourceLocation opcLoc,
+                                           bool captureSetValueAsResult) {
+  if (!findAtIndexSetter())
+    return ExprError();
+  
+  QualType receiverType = InstanceBase->getType();
+  Expr *Index = InstanceKey;
+  
+  // Arguments.
+  Expr *args[] = { op, Index };
+  
+  // Build a message-send.
+  ExprResult msg = S.BuildInstanceMessageImplicit(InstanceBase, receiverType,
+                                                  GenericLoc,
+                                                  AtIndexSetterSelector,
+                                                  AtIndexSetter,
+                                                  MultiExprArg(args, 2));
+  
+  if (!msg.isInvalid() && captureSetValueAsResult) {
+    ObjCMessageExpr *msgExpr =
+      cast<ObjCMessageExpr>(msg.get()->IgnoreImplicit());
+    Expr *arg = msgExpr->getArg(0);
+    msgExpr->setArg(0, captureValueAsResult(arg));
+  }
+  
+  return msg;
+}
+
+//===----------------------------------------------------------------------===//
+//  General Sema routines.
+//===----------------------------------------------------------------------===//
+
+ExprResult Sema::checkPseudoObjectRValue(Expr *E) {
+  Expr *opaqueRef = E->IgnoreParens();
+  if (ObjCPropertyRefExpr *refExpr
+        = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
+    ObjCPropertyOpBuilder builder(*this, refExpr);
+    return builder.buildRValueOperation(E);
+  }
+  else if (ObjCSubscriptRefExpr *refExpr
+           = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
+    ObjCSubscriptOpBuilder builder(*this, refExpr);
+    return builder.buildRValueOperation(E);
+  } else {
+    llvm_unreachable("unknown pseudo-object kind!");
+  }
+}
+
+/// Check an increment or decrement of a pseudo-object expression.
+ExprResult Sema::checkPseudoObjectIncDec(Scope *Sc, SourceLocation opcLoc,
+                                         UnaryOperatorKind opcode, Expr *op) {
+  // Do nothing if the operand is dependent.
+  if (op->isTypeDependent())
+    return new (Context) UnaryOperator(op, opcode, Context.DependentTy,
+                                       VK_RValue, OK_Ordinary, opcLoc);
+
+  assert(UnaryOperator::isIncrementDecrementOp(opcode));
+  Expr *opaqueRef = op->IgnoreParens();
+  if (ObjCPropertyRefExpr *refExpr
+        = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
+    ObjCPropertyOpBuilder builder(*this, refExpr);
+    return builder.buildIncDecOperation(Sc, opcLoc, opcode, op);
+  } else if (isa<ObjCSubscriptRefExpr>(opaqueRef)) {
+    Diag(opcLoc, diag::err_illegal_container_subscripting_op);
+    return ExprError();
+  } else {
+    llvm_unreachable("unknown pseudo-object kind!");
+  }
+}
+
+ExprResult Sema::checkPseudoObjectAssignment(Scope *S, SourceLocation opcLoc,
+                                             BinaryOperatorKind opcode,
+                                             Expr *LHS, Expr *RHS) {
+  // Do nothing if either argument is dependent.
+  if (LHS->isTypeDependent() || RHS->isTypeDependent())
+    return new (Context) BinaryOperator(LHS, RHS, opcode, Context.DependentTy,
+                                        VK_RValue, OK_Ordinary, opcLoc);
+
+  // Filter out non-overload placeholder types in the RHS.
+  if (RHS->getType()->isNonOverloadPlaceholderType()) {
+    ExprResult result = CheckPlaceholderExpr(RHS);
+    if (result.isInvalid()) return ExprError();
+    RHS = result.take();
+  }
+
+  Expr *opaqueRef = LHS->IgnoreParens();
+  if (ObjCPropertyRefExpr *refExpr
+        = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
+    ObjCPropertyOpBuilder builder(*this, refExpr);
+    return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
+  } else if (ObjCSubscriptRefExpr *refExpr
+             = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
+    ObjCSubscriptOpBuilder builder(*this, refExpr);
+    return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
+  } else {
+    llvm_unreachable("unknown pseudo-object kind!");
+  }
+}
+
+/// Given a pseudo-object reference, rebuild it without the opaque
+/// values.  Basically, undo the behavior of rebuildAndCaptureObject.
+/// This should never operate in-place.
+static Expr *stripOpaqueValuesFromPseudoObjectRef(Sema &S, Expr *E) {
+  Expr *opaqueRef = E->IgnoreParens();
+  if (ObjCPropertyRefExpr *refExpr
+        = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
+    // Class and super property references don't have opaque values in them.
+    if (refExpr->isClassReceiver() || refExpr->isSuperReceiver())
+      return E;
+    
+    assert(refExpr->isObjectReceiver() && "Unknown receiver kind?");
+    OpaqueValueExpr *baseOVE = cast<OpaqueValueExpr>(refExpr->getBase());
+    return ObjCPropertyRefRebuilder(S, baseOVE->getSourceExpr()).rebuild(E);
+  } else if (ObjCSubscriptRefExpr *refExpr
+               = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
+    OpaqueValueExpr *baseOVE = cast<OpaqueValueExpr>(refExpr->getBaseExpr());
+    OpaqueValueExpr *keyOVE = cast<OpaqueValueExpr>(refExpr->getKeyExpr());
+    return ObjCSubscriptRefRebuilder(S, baseOVE->getSourceExpr(), 
+                                     keyOVE->getSourceExpr()).rebuild(E);
+  } else {
+    llvm_unreachable("unknown pseudo-object kind!");
+  }
+}
+
+/// Given a pseudo-object expression, recreate what it looks like
+/// syntactically without the attendant OpaqueValueExprs.
+///
+/// This is a hack which should be removed when TreeTransform is
+/// capable of rebuilding a tree without stripping implicit
+/// operations.
+Expr *Sema::recreateSyntacticForm(PseudoObjectExpr *E) {
+  Expr *syntax = E->getSyntacticForm();
+  if (UnaryOperator *uop = dyn_cast<UnaryOperator>(syntax)) {
+    Expr *op = stripOpaqueValuesFromPseudoObjectRef(*this, uop->getSubExpr());
+    return new (Context) UnaryOperator(op, uop->getOpcode(), uop->getType(),
+                                       uop->getValueKind(), uop->getObjectKind(),
+                                       uop->getOperatorLoc());
+  } else if (CompoundAssignOperator *cop
+               = dyn_cast<CompoundAssignOperator>(syntax)) {
+    Expr *lhs = stripOpaqueValuesFromPseudoObjectRef(*this, cop->getLHS());
+    Expr *rhs = cast<OpaqueValueExpr>(cop->getRHS())->getSourceExpr();
+    return new (Context) CompoundAssignOperator(lhs, rhs, cop->getOpcode(),
+                                                cop->getType(),
+                                                cop->getValueKind(),
+                                                cop->getObjectKind(),
+                                                cop->getComputationLHSType(),
+                                                cop->getComputationResultType(),
+                                                cop->getOperatorLoc());
+  } else if (BinaryOperator *bop = dyn_cast<BinaryOperator>(syntax)) {
+    Expr *lhs = stripOpaqueValuesFromPseudoObjectRef(*this, bop->getLHS());
+    Expr *rhs = cast<OpaqueValueExpr>(bop->getRHS())->getSourceExpr();
+    return new (Context) BinaryOperator(lhs, rhs, bop->getOpcode(),
+                                        bop->getType(), bop->getValueKind(),
+                                        bop->getObjectKind(),
+                                        bop->getOperatorLoc());
+  } else {
+    assert(syntax->hasPlaceholderType(BuiltinType::PseudoObject));
+    return stripOpaqueValuesFromPseudoObjectRef(*this, syntax);
+  }
+}