Import Clang, at r72732.vendor/clang/clang-r72732

1 files changed, 5395 insertions, 0 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
new file mode 100644
index 000000000000..ee5132a7d8e0
--- /dev/null
+++ b/lib/Sema/SemaExpr.cpp
@@ -0,0 +1,5395 @@
+//===--- SemaExpr.cpp - Semantic Analysis for Expressions -----------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Sema.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/AST/DeclTemplate.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/LiteralSupport.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/Parse/DeclSpec.h"
+#include "clang/Parse/Designator.h"
+#include "clang/Parse/Scope.h"
+using namespace clang;
+
+/// \brief Determine whether the use of this declaration is valid, and
+/// emit any corresponding diagnostics.
+///
+/// This routine diagnoses various problems with referencing
+/// declarations that can occur when using a declaration. For example,
+/// it might warn if a deprecated or unavailable declaration is being
+/// used, or produce an error (and return true) if a C++0x deleted
+/// function is being used.
+///
+/// \returns true if there was an error (this declaration cannot be
+/// referenced), false otherwise.
+bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc) {
+  // See if the decl is deprecated.
+  if (D->getAttr<DeprecatedAttr>()) {
+    // Implementing deprecated stuff requires referencing deprecated
+    // stuff. Don't warn if we are implementing a deprecated
+    // construct.
+    bool isSilenced = false;
+    
+    if (NamedDecl *ND = getCurFunctionOrMethodDecl()) {
+      // If this reference happens *in* a deprecated function or method, don't
+      // warn.
+      isSilenced = ND->getAttr<DeprecatedAttr>();
+      
+      // If this is an Objective-C method implementation, check to see if the
+      // method was deprecated on the declaration, not the definition.
+      if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(ND)) {
+        // The semantic decl context of a ObjCMethodDecl is the
+        // ObjCImplementationDecl.
+        if (ObjCImplementationDecl *Impl
+              = dyn_cast<ObjCImplementationDecl>(MD->getParent())) {
+          
+          MD = Impl->getClassInterface()->getMethod(Context, 
+                                                    MD->getSelector(),
+                                                    MD->isInstanceMethod());
+          isSilenced |= MD && MD->getAttr<DeprecatedAttr>();
+        }
+      }
+    }
+    
+    if (!isSilenced)
+      Diag(Loc, diag::warn_deprecated) << D->getDeclName();
+  }
+
+  // See if this is a deleted function.
+  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    if (FD->isDeleted()) {
+      Diag(Loc, diag::err_deleted_function_use);
+      Diag(D->getLocation(), diag::note_unavailable_here) << true;
+      return true;
+    }
+  }
+
+  // See if the decl is unavailable
+  if (D->getAttr<UnavailableAttr>()) {
+    Diag(Loc, diag::warn_unavailable) << D->getDeclName();
+    Diag(D->getLocation(), diag::note_unavailable_here) << 0;
+  }
+
+  return false;
+}
+
+/// DiagnoseSentinelCalls - This routine checks on method dispatch calls
+/// (and other functions in future), which have been declared with sentinel 
+/// attribute. It warns if call does not have the sentinel argument.
+///
+void Sema::DiagnoseSentinelCalls(NamedDecl *D, SourceLocation Loc,
+                                 Expr **Args, unsigned NumArgs)
+{
+  const SentinelAttr *attr = D->getAttr<SentinelAttr>();
+  if (!attr) 
+    return;
+  int sentinelPos = attr->getSentinel();
+  int nullPos = attr->getNullPos();
+  
+  // FIXME. ObjCMethodDecl and FunctionDecl need be derived from the same common
+  // base class. Then we won't be needing two versions of the same code.
+  unsigned int i = 0;
+  bool warnNotEnoughArgs = false;
+  int isMethod = 0;
+  if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
+    // skip over named parameters.
+    ObjCMethodDecl::param_iterator P, E = MD->param_end();
+    for (P = MD->param_begin(); (P != E && i < NumArgs); ++P) {
+      if (nullPos)
+        --nullPos;
+      else
+        ++i;
+    }
+    warnNotEnoughArgs = (P != E || i >= NumArgs);
+    isMethod = 1;
+  }
+  else if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    // skip over named parameters.
+    ObjCMethodDecl::param_iterator P, E = FD->param_end();
+    for (P = FD->param_begin(); (P != E && i < NumArgs); ++P) {
+      if (nullPos)
+        --nullPos;
+      else
+        ++i;
+    }
+    warnNotEnoughArgs = (P != E || i >= NumArgs);
+  }
+  else if (VarDecl *V = dyn_cast<VarDecl>(D)) {
+    // block or function pointer call.
+    QualType Ty = V->getType();
+    if (Ty->isBlockPointerType() || Ty->isFunctionPointerType()) {
+      const FunctionType *FT = Ty->isFunctionPointerType() 
+      ? Ty->getAsPointerType()->getPointeeType()->getAsFunctionType()
+      : Ty->getAsBlockPointerType()->getPointeeType()->getAsFunctionType();
+      if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) {
+        unsigned NumArgsInProto = Proto->getNumArgs();
+        unsigned k;
+        for (k = 0; (k != NumArgsInProto && i < NumArgs); k++) {
+          if (nullPos)
+            --nullPos;
+          else
+            ++i;
+        }
+        warnNotEnoughArgs = (k != NumArgsInProto || i >= NumArgs);
+      }
+      if (Ty->isBlockPointerType())
+        isMethod = 2;
+    }
+    else
+      return;
+  }
+  else
+    return;
+
+  if (warnNotEnoughArgs) {
+    Diag(Loc, diag::warn_not_enough_argument) << D->getDeclName();
+    Diag(D->getLocation(), diag::note_sentinel_here) << isMethod;
+    return;
+  }
+  int sentinel = i;
+  while (sentinelPos > 0 && i < NumArgs-1) {
+    --sentinelPos;
+    ++i;
+  }
+  if (sentinelPos > 0) {
+    Diag(Loc, diag::warn_not_enough_argument) << D->getDeclName();
+    Diag(D->getLocation(), diag::note_sentinel_here) << isMethod;
+    return;
+  }
+  while (i < NumArgs-1) {
+    ++i;
+    ++sentinel;
+  }
+  Expr *sentinelExpr = Args[sentinel];
+  if (sentinelExpr && (!sentinelExpr->getType()->isPointerType() ||
+                       !sentinelExpr->isNullPointerConstant(Context))) {
+    Diag(Loc, diag::warn_missing_sentinel) << isMethod;
+    Diag(D->getLocation(), diag::note_sentinel_here) << isMethod;
+  }
+  return;
+}
+
+SourceRange Sema::getExprRange(ExprTy *E) const {
+  Expr *Ex = (Expr *)E;
+  return Ex? Ex->getSourceRange() : SourceRange();
+}
+
+//===----------------------------------------------------------------------===//
+//  Standard Promotions and Conversions
+//===----------------------------------------------------------------------===//
+
+/// DefaultFunctionArrayConversion (C99 6.3.2.1p3, C99 6.3.2.1p4).
+void Sema::DefaultFunctionArrayConversion(Expr *&E) {
+  QualType Ty = E->getType();
+  assert(!Ty.isNull() && "DefaultFunctionArrayConversion - missing type");
+
+  if (Ty->isFunctionType())
+    ImpCastExprToType(E, Context.getPointerType(Ty));
+  else if (Ty->isArrayType()) {
+    // In C90 mode, arrays only promote to pointers if the array expression is
+    // an lvalue.  The relevant legalese is C90 6.2.2.1p3: "an lvalue that has
+    // type 'array of type' is converted to an expression that has type 'pointer
+    // to type'...".  In C99 this was changed to: C99 6.3.2.1p3: "an expression
+    // that has type 'array of type' ...".  The relevant change is "an lvalue"
+    // (C90) to "an expression" (C99).
+    //
+    // C++ 4.2p1:
+    // An lvalue or rvalue of type "array of N T" or "array of unknown bound of
+    // T" can be converted to an rvalue of type "pointer to T".
+    //
+    if (getLangOptions().C99 || getLangOptions().CPlusPlus ||
+        E->isLvalue(Context) == Expr::LV_Valid)
+      ImpCastExprToType(E, Context.getArrayDecayedType(Ty));
+  }
+}
+
+/// \brief Whether this is a promotable bitfield reference according
+/// to C99 6.3.1.1p2, bullet 2.
+///
+/// \returns the type this bit-field will promote to, or NULL if no
+/// promotion occurs.
+static QualType isPromotableBitField(Expr *E, ASTContext &Context) {
+  FieldDecl *Field = E->getBitField();
+  if (!Field)
+    return QualType();
+
+  const BuiltinType *BT = Field->getType()->getAsBuiltinType();
+  if (!BT)
+    return QualType();
+
+  if (BT->getKind() != BuiltinType::Bool &&
+      BT->getKind() != BuiltinType::Int &&
+      BT->getKind() != BuiltinType::UInt) 
+    return QualType();
+
+  llvm::APSInt BitWidthAP;
+  if (!Field->getBitWidth()->isIntegerConstantExpr(BitWidthAP, Context))
+    return QualType();
+
+  uint64_t BitWidth = BitWidthAP.getZExtValue();
+  uint64_t IntSize = Context.getTypeSize(Context.IntTy);
+  if (BitWidth < IntSize ||
+      (Field->getType()->isSignedIntegerType() && BitWidth == IntSize))
+    return Context.IntTy;
+
+  if (BitWidth == IntSize && Field->getType()->isUnsignedIntegerType())
+    return Context.UnsignedIntTy;
+
+  return QualType();
+}
+
+/// UsualUnaryConversions - Performs various conversions that are common to most
+/// operators (C99 6.3). The conversions of array and function types are 
+/// sometimes surpressed. For example, the array->pointer conversion doesn't
+/// apply if the array is an argument to the sizeof or address (&) operators.
+/// In these instances, this routine should *not* be called.
+Expr *Sema::UsualUnaryConversions(Expr *&Expr) {
+  QualType Ty = Expr->getType();
+  assert(!Ty.isNull() && "UsualUnaryConversions - missing type");
+  
+  // C99 6.3.1.1p2:
+  //
+  //   The following may be used in an expression wherever an int or
+  //   unsigned int may be used:
+  //     - an object or expression with an integer type whose integer
+  //       conversion rank is less than or equal to the rank of int
+  //       and unsigned int.
+  //     - A bit-field of type _Bool, int, signed int, or unsigned int.
+  //
+  //   If an int can represent all values of the original type, the
+  //   value is converted to an int; otherwise, it is converted to an
+  //   unsigned int. These are called the integer promotions. All
+  //   other types are unchanged by the integer promotions.
+  if (Ty->isPromotableIntegerType()) {
+    ImpCastExprToType(Expr, Context.IntTy);
+    return Expr;
+  } else {
+    QualType T = isPromotableBitField(Expr, Context);
+    if (!T.isNull()) {
+      ImpCastExprToType(Expr, T);
+      return Expr;
+    }
+  } 
+    
+  DefaultFunctionArrayConversion(Expr);
+  return Expr;
+}
+
+/// DefaultArgumentPromotion (C99 6.5.2.2p6). Used for function calls that
+/// do not have a prototype. Arguments that have type float are promoted to 
+/// double. All other argument types are converted by UsualUnaryConversions().
+void Sema::DefaultArgumentPromotion(Expr *&Expr) {
+  QualType Ty = Expr->getType();
+  assert(!Ty.isNull() && "DefaultArgumentPromotion - missing type");
+  
+  // If this is a 'float' (CVR qualified or typedef) promote to double.
+  if (const BuiltinType *BT = Ty->getAsBuiltinType())
+    if (BT->getKind() == BuiltinType::Float)
+      return ImpCastExprToType(Expr, Context.DoubleTy);
+  
+  UsualUnaryConversions(Expr);
+}
+
+/// DefaultVariadicArgumentPromotion - Like DefaultArgumentPromotion, but
+/// will warn if the resulting type is not a POD type, and rejects ObjC
+/// interfaces passed by value.  This returns true if the argument type is
+/// completely illegal.
+bool Sema::DefaultVariadicArgumentPromotion(Expr *&Expr, VariadicCallType CT) {
+  DefaultArgumentPromotion(Expr);
+  
+  if (Expr->getType()->isObjCInterfaceType()) {
+    Diag(Expr->getLocStart(),
+         diag::err_cannot_pass_objc_interface_to_vararg)
+      << Expr->getType() << CT;
+    return true;
+  }
+  
+  if (!Expr->getType()->isPODType())
+    Diag(Expr->getLocStart(), diag::warn_cannot_pass_non_pod_arg_to_vararg)
+      << Expr->getType() << CT;
+
+  return false;
+}
+
+
+/// UsualArithmeticConversions - Performs various conversions that are common to
+/// binary operators (C99 6.3.1.8). If both operands aren't arithmetic, this
+/// routine returns the first non-arithmetic type found. The client is 
+/// responsible for emitting appropriate error diagnostics.
+/// FIXME: verify the conversion rules for "complex int" are consistent with
+/// GCC.
+QualType Sema::UsualArithmeticConversions(Expr *&lhsExpr, Expr *&rhsExpr,
+                                          bool isCompAssign) {
+  if (!isCompAssign)
+    UsualUnaryConversions(lhsExpr);
+
+  UsualUnaryConversions(rhsExpr);
+
+  // For conversion purposes, we ignore any qualifiers. 
+  // For example, "const float" and "float" are equivalent.
+  QualType lhs =
+    Context.getCanonicalType(lhsExpr->getType()).getUnqualifiedType();
+  QualType rhs = 
+    Context.getCanonicalType(rhsExpr->getType()).getUnqualifiedType();
+
+  // If both types are identical, no conversion is needed.
+  if (lhs == rhs)
+    return lhs;
+
+  // If either side is a non-arithmetic type (e.g. a pointer), we are done.
+  // The caller can deal with this (e.g. pointer + int).
+  if (!lhs->isArithmeticType() || !rhs->isArithmeticType())
+    return lhs;
+
+  // Perform bitfield promotions.
+  QualType LHSBitfieldPromoteTy = isPromotableBitField(lhsExpr, Context);
+  if (!LHSBitfieldPromoteTy.isNull())
+    lhs = LHSBitfieldPromoteTy;
+  QualType RHSBitfieldPromoteTy = isPromotableBitField(rhsExpr, Context);
+  if (!RHSBitfieldPromoteTy.isNull())
+    rhs = RHSBitfieldPromoteTy;
+
+  QualType destType = UsualArithmeticConversionsType(lhs, rhs);
+  if (!isCompAssign)
+    ImpCastExprToType(lhsExpr, destType);
+  ImpCastExprToType(rhsExpr, destType);
+  return destType;
+}
+
+QualType Sema::UsualArithmeticConversionsType(QualType lhs, QualType rhs) {
+  // Perform the usual unary conversions. We do this early so that
+  // integral promotions to "int" can allow us to exit early, in the
+  // lhs == rhs check. Also, for conversion purposes, we ignore any
+  // qualifiers.  For example, "const float" and "float" are
+  // equivalent.
+  if (lhs->isPromotableIntegerType())
+    lhs = Context.IntTy;
+  else
+    lhs = lhs.getUnqualifiedType();
+  if (rhs->isPromotableIntegerType())
+    rhs = Context.IntTy;
+  else
+    rhs = rhs.getUnqualifiedType();
+
+  // If both types are identical, no conversion is needed.
+  if (lhs == rhs)
+    return lhs;
+  
+  // If either side is a non-arithmetic type (e.g. a pointer), we are done.
+  // The caller can deal with this (e.g. pointer + int).
+  if (!lhs->isArithmeticType() || !rhs->isArithmeticType())
+    return lhs;
+    
+  // At this point, we have two different arithmetic types. 
+  
+  // Handle complex types first (C99 6.3.1.8p1).
+  if (lhs->isComplexType() || rhs->isComplexType()) {
+    // if we have an integer operand, the result is the complex type.
+    if (rhs->isIntegerType() || rhs->isComplexIntegerType()) { 
+      // convert the rhs to the lhs complex type.
+      return lhs;
+    }
+    if (lhs->isIntegerType() || lhs->isComplexIntegerType()) { 
+      // convert the lhs to the rhs complex type.
+      return rhs;
+    }
+    // This handles complex/complex, complex/float, or float/complex.
+    // When both operands are complex, the shorter operand is converted to the 
+    // type of the longer, and that is the type of the result. This corresponds 
+    // to what is done when combining two real floating-point operands. 
+    // The fun begins when size promotion occur across type domains. 
+    // From H&S 6.3.4: When one operand is complex and the other is a real
+    // floating-point type, the less precise type is converted, within it's 
+    // real or complex domain, to the precision of the other type. For example,
+    // when combining a "long double" with a "double _Complex", the 
+    // "double _Complex" is promoted to "long double _Complex".
+    int result = Context.getFloatingTypeOrder(lhs, rhs);
+    
+    if (result > 0) { // The left side is bigger, convert rhs. 
+      rhs = Context.getFloatingTypeOfSizeWithinDomain(lhs, rhs);
+    } else if (result < 0) { // The right side is bigger, convert lhs. 
+      lhs = Context.getFloatingTypeOfSizeWithinDomain(rhs, lhs);
+    } 
+    // At this point, lhs and rhs have the same rank/size. Now, make sure the
+    // domains match. This is a requirement for our implementation, C99
+    // does not require this promotion.
+    if (lhs != rhs) { // Domains don't match, we have complex/float mix.
+      if (lhs->isRealFloatingType()) { // handle "double, _Complex double".
+        return rhs;
+      } else { // handle "_Complex double, double".
+        return lhs;
+      }
+    }
+    return lhs; // The domain/size match exactly.
+  }
+  // Now handle "real" floating types (i.e. float, double, long double).
+  if (lhs->isRealFloatingType() || rhs->isRealFloatingType()) {
+    // if we have an integer operand, the result is the real floating type.
+    if (rhs->isIntegerType()) {
+      // convert rhs to the lhs floating point type.
+      return lhs;
+    }
+    if (rhs->isComplexIntegerType()) {
+      // convert rhs to the complex floating point type.
+      return Context.getComplexType(lhs);
+    }
+    if (lhs->isIntegerType()) {
+      // convert lhs to the rhs floating point type.
+      return rhs;
+    }
+    if (lhs->isComplexIntegerType()) { 
+      // convert lhs to the complex floating point type.
+      return Context.getComplexType(rhs);
+    }
+    // We have two real floating types, float/complex combos were handled above.
+    // Convert the smaller operand to the bigger result.
+    int result = Context.getFloatingTypeOrder(lhs, rhs);
+    if (result > 0) // convert the rhs
+      return lhs;
+    assert(result < 0 && "illegal float comparison");
+    return rhs;   // convert the lhs
+  }
+  if (lhs->isComplexIntegerType() || rhs->isComplexIntegerType()) {
+    // Handle GCC complex int extension.
+    const ComplexType *lhsComplexInt = lhs->getAsComplexIntegerType();
+    const ComplexType *rhsComplexInt = rhs->getAsComplexIntegerType();
+
+    if (lhsComplexInt && rhsComplexInt) {
+      if (Context.getIntegerTypeOrder(lhsComplexInt->getElementType(), 
+                                      rhsComplexInt->getElementType()) >= 0)
+        return lhs; // convert the rhs
+      return rhs;
+    } else if (lhsComplexInt && rhs->isIntegerType()) {
+      // convert the rhs to the lhs complex type.
+      return lhs;
+    } else if (rhsComplexInt && lhs->isIntegerType()) {
+      // convert the lhs to the rhs complex type.
+      return rhs;
+    }
+  }
+  // Finally, we have two differing integer types.
+  // The rules for this case are in C99 6.3.1.8
+  int compare = Context.getIntegerTypeOrder(lhs, rhs);
+  bool lhsSigned = lhs->isSignedIntegerType(),
+       rhsSigned = rhs->isSignedIntegerType();
+  QualType destType;
+  if (lhsSigned == rhsSigned) {
+    // Same signedness; use the higher-ranked type
+    destType = compare >= 0 ? lhs : rhs;
+  } else if (compare != (lhsSigned ? 1 : -1)) {
+    // The unsigned type has greater than or equal rank to the
+    // signed type, so use the unsigned type
+    destType = lhsSigned ? rhs : lhs;
+  } else if (Context.getIntWidth(lhs) != Context.getIntWidth(rhs)) {
+    // The two types are different widths; if we are here, that
+    // means the signed type is larger than the unsigned type, so
+    // use the signed type.
+    destType = lhsSigned ? lhs : rhs;
+  } else {
+    // The signed type is higher-ranked than the unsigned type,
+    // but isn't actually any bigger (like unsigned int and long
+    // on most 32-bit systems).  Use the unsigned type corresponding
+    // to the signed type.
+    destType = Context.getCorrespondingUnsignedType(lhsSigned ? lhs : rhs);
+  }
+  return destType;
+}
+
+//===----------------------------------------------------------------------===//
+//  Semantic Analysis for various Expression Types
+//===----------------------------------------------------------------------===//
+
+
+/// ActOnStringLiteral - The specified tokens were lexed as pasted string
+/// fragments (e.g. "foo" "bar" L"baz").  The result string has to handle string
+/// concatenation ([C99 5.1.1.2, translation phase #6]), so it may come from
+/// multiple tokens.  However, the common case is that StringToks points to one
+/// string.
+///
+Action::OwningExprResult
+Sema::ActOnStringLiteral(const Token *StringToks, unsigned NumStringToks) {
+  assert(NumStringToks && "Must have at least one string!");
+
+  StringLiteralParser Literal(StringToks, NumStringToks, PP);
+  if (Literal.hadError)
+    return ExprError();
+
+  llvm::SmallVector<SourceLocation, 4> StringTokLocs;
+  for (unsigned i = 0; i != NumStringToks; ++i)
+    StringTokLocs.push_back(StringToks[i].getLocation());
+
+  QualType StrTy = Context.CharTy;
+  if (Literal.AnyWide) StrTy = Context.getWCharType();
+  if (Literal.Pascal) StrTy = Context.UnsignedCharTy;
+
+  // A C++ string literal has a const-qualified element type (C++ 2.13.4p1).
+  if (getLangOptions().CPlusPlus)
+    StrTy.addConst();
+
+  // Get an array type for the string, according to C99 6.4.5.  This includes
+  // the nul terminator character as well as the string length for pascal
+  // strings.
+  StrTy = Context.getConstantArrayType(StrTy,
+                                 llvm::APInt(32, Literal.GetNumStringChars()+1),
+                                       ArrayType::Normal, 0);
+  
+  // Pass &StringTokLocs[0], StringTokLocs.size() to factory!
+  return Owned(StringLiteral::Create(Context, Literal.GetString(), 
+                                     Literal.GetStringLength(),
+                                     Literal.AnyWide, StrTy,
+                                     &StringTokLocs[0],
+                                     StringTokLocs.size()));
+}
+
+/// ShouldSnapshotBlockValueReference - Return true if a reference inside of
+/// CurBlock to VD should cause it to be snapshotted (as we do for auto
+/// variables defined outside the block) or false if this is not needed (e.g.
+/// for values inside the block or for globals).
+///
+/// This also keeps the 'hasBlockDeclRefExprs' in the BlockSemaInfo records
+/// up-to-date.
+///
+static bool ShouldSnapshotBlockValueReference(BlockSemaInfo *CurBlock,
+                                              ValueDecl *VD) {
+  // If the value is defined inside the block, we couldn't snapshot it even if
+  // we wanted to.
+  if (CurBlock->TheDecl == VD->getDeclContext())
+    return false;
+  
+  // If this is an enum constant or function, it is constant, don't snapshot.
+  if (isa<EnumConstantDecl>(VD) || isa<FunctionDecl>(VD))
+    return false;
+
+  // If this is a reference to an extern, static, or global variable, no need to
+  // snapshot it.
+  // FIXME: What about 'const' variables in C++?
+  if (const VarDecl *Var = dyn_cast<VarDecl>(VD))
+    if (!Var->hasLocalStorage())
+      return false;
+  
+  // Blocks that have these can't be constant.
+  CurBlock->hasBlockDeclRefExprs = true;
+
+  // If we have nested blocks, the decl may be declared in an outer block (in
+  // which case that outer block doesn't get "hasBlockDeclRefExprs") or it may
+  // be defined outside all of the current blocks (in which case the blocks do
+  // all get the bit).  Walk the nesting chain.
+  for (BlockSemaInfo *NextBlock = CurBlock->PrevBlockInfo; NextBlock;
+       NextBlock = NextBlock->PrevBlockInfo) {
+    // If we found the defining block for the variable, don't mark the block as
+    // having a reference outside it.
+    if (NextBlock->TheDecl == VD->getDeclContext())
+      break;
+    
+    // Otherwise, the DeclRef from the inner block causes the outer one to need
+    // a snapshot as well.
+    NextBlock->hasBlockDeclRefExprs = true;
+  }
+  
+  return true;
+}  
+    
+
+
+/// ActOnIdentifierExpr - The parser read an identifier in expression context,
+/// validate it per-C99 6.5.1.  HasTrailingLParen indicates whether this
+/// identifier is used in a function call context.
+/// SS is only used for a C++ qualified-id (foo::bar) to indicate the
+/// class or namespace that the identifier must be a member of.
+Sema::OwningExprResult Sema::ActOnIdentifierExpr(Scope *S, SourceLocation Loc,
+                                                 IdentifierInfo &II,
+                                                 bool HasTrailingLParen,
+                                                 const CXXScopeSpec *SS,
+                                                 bool isAddressOfOperand) {
+  return ActOnDeclarationNameExpr(S, Loc, &II, HasTrailingLParen, SS,
+                                  isAddressOfOperand);
+}
+
+/// BuildDeclRefExpr - Build either a DeclRefExpr or a
+/// QualifiedDeclRefExpr based on whether or not SS is a
+/// nested-name-specifier.
+DeclRefExpr *
+Sema::BuildDeclRefExpr(NamedDecl *D, QualType Ty, SourceLocation Loc,
+                       bool TypeDependent, bool ValueDependent,
+                       const CXXScopeSpec *SS) {
+  if (SS && !SS->isEmpty()) {
+    return new (Context) QualifiedDeclRefExpr(D, Ty, Loc, TypeDependent, 
+                                              ValueDependent, SS->getRange(),
+                  static_cast<NestedNameSpecifier *>(SS->getScopeRep()));
+  } else
+    return new (Context) DeclRefExpr(D, Ty, Loc, TypeDependent, ValueDependent);
+}
+
+/// getObjectForAnonymousRecordDecl - Retrieve the (unnamed) field or
+/// variable corresponding to the anonymous union or struct whose type
+/// is Record.
+static Decl *getObjectForAnonymousRecordDecl(ASTContext &Context,
+                                             RecordDecl *Record) {
+  assert(Record->isAnonymousStructOrUnion() && 
+         "Record must be an anonymous struct or union!");
+  
+  // FIXME: Once Decls are directly linked together, this will be an O(1)
+  // operation rather than a slow walk through DeclContext's vector (which
+  // itself will be eliminated). DeclGroups might make this even better.
+  DeclContext *Ctx = Record->getDeclContext();
+  for (DeclContext::decl_iterator D = Ctx->decls_begin(Context), 
+                               DEnd = Ctx->decls_end(Context);
+       D != DEnd; ++D) {
+    if (*D == Record) {
+      // The object for the anonymous struct/union directly
+      // follows its type in the list of declarations.
+      ++D;
+      assert(D != DEnd && "Missing object for anonymous record");
+      assert(!cast<NamedDecl>(*D)->getDeclName() && "Decl should be unnamed");
+      return *D;
+    }
+  }
+
+  assert(false && "Missing object for anonymous record");
+  return 0;
+}
+
+/// \brief Given a field that represents a member of an anonymous
+/// struct/union, build the path from that field's context to the
+/// actual member.
+///
+/// Construct the sequence of field member references we'll have to
+/// perform to get to the field in the anonymous union/struct. The
+/// list of members is built from the field outward, so traverse it
+/// backwards to go from an object in the current context to the field
+/// we found.
+///
+/// \returns The variable from which the field access should begin,
+/// for an anonymous struct/union that is not a member of another
+/// class. Otherwise, returns NULL.
+VarDecl *Sema::BuildAnonymousStructUnionMemberPath(FieldDecl *Field,
+                                   llvm::SmallVectorImpl<FieldDecl *> &Path) {
+  assert(Field->getDeclContext()->isRecord() &&
+         cast<RecordDecl>(Field->getDeclContext())->isAnonymousStructOrUnion()
+         && "Field must be stored inside an anonymous struct or union");
+
+  Path.push_back(Field);
+  VarDecl *BaseObject = 0;
+  DeclContext *Ctx = Field->getDeclContext();
+  do {
+    RecordDecl *Record = cast<RecordDecl>(Ctx);
+    Decl *AnonObject = getObjectForAnonymousRecordDecl(Context, Record);
+    if (FieldDecl *AnonField = dyn_cast<FieldDecl>(AnonObject))
+      Path.push_back(AnonField);
+    else {
+      BaseObject = cast<VarDecl>(AnonObject);
+      break;
+    }
+    Ctx = Ctx->getParent();
+  } while (Ctx->isRecord() && 
+           cast<RecordDecl>(Ctx)->isAnonymousStructOrUnion());
+
+  return BaseObject;
+}
+
+Sema::OwningExprResult
+Sema::BuildAnonymousStructUnionMemberReference(SourceLocation Loc,
+                                               FieldDecl *Field,
+                                               Expr *BaseObjectExpr,
+                                               SourceLocation OpLoc) {
+  llvm::SmallVector<FieldDecl *, 4> AnonFields;
+  VarDecl *BaseObject = BuildAnonymousStructUnionMemberPath(Field, 
+                                                            AnonFields);
+
+  // Build the expression that refers to the base object, from
+  // which we will build a sequence of member references to each
+  // of the anonymous union objects and, eventually, the field we
+  // found via name lookup.
+  bool BaseObjectIsPointer = false;
+  unsigned ExtraQuals = 0;
+  if (BaseObject) {
+    // BaseObject is an anonymous struct/union variable (and is,
+    // therefore, not part of another non-anonymous record).
+    if (BaseObjectExpr) BaseObjectExpr->Destroy(Context);
+    BaseObjectExpr = new (Context) DeclRefExpr(BaseObject,BaseObject->getType(),
+                                               SourceLocation());
+    ExtraQuals 
+      = Context.getCanonicalType(BaseObject->getType()).getCVRQualifiers();
+  } else if (BaseObjectExpr) {
+    // The caller provided the base object expression. Determine
+    // whether its a pointer and whether it adds any qualifiers to the
+    // anonymous struct/union fields we're looking into.
+    QualType ObjectType = BaseObjectExpr->getType();
+    if (const PointerType *ObjectPtr = ObjectType->getAsPointerType()) {
+      BaseObjectIsPointer = true;
+      ObjectType = ObjectPtr->getPointeeType();
+    }
+    ExtraQuals = Context.getCanonicalType(ObjectType).getCVRQualifiers();
+  } else {
+    // We've found a member of an anonymous struct/union that is
+    // inside a non-anonymous struct/union, so in a well-formed
+    // program our base object expression is "this".
+    if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(CurContext)) {
+      if (!MD->isStatic()) {
+        QualType AnonFieldType 
+          = Context.getTagDeclType(
+                     cast<RecordDecl>(AnonFields.back()->getDeclContext()));
+        QualType ThisType = Context.getTagDeclType(MD->getParent());
+        if ((Context.getCanonicalType(AnonFieldType) 
+               == Context.getCanonicalType(ThisType)) ||
+            IsDerivedFrom(ThisType, AnonFieldType)) {
+          // Our base object expression is "this".
+          BaseObjectExpr = new (Context) CXXThisExpr(SourceLocation(),
+                                                     MD->getThisType(Context));
+          BaseObjectIsPointer = true;
+        }
+      } else {
+        return ExprError(Diag(Loc,diag::err_invalid_member_use_in_static_method)
+          << Field->getDeclName());
+      }
+      ExtraQuals = MD->getTypeQualifiers();
+    }
+
+    if (!BaseObjectExpr) 
+      return ExprError(Diag(Loc, diag::err_invalid_non_static_member_use)
+        << Field->getDeclName());
+  }
+
+  // Build the implicit member references to the field of the
+  // anonymous struct/union.
+  Expr *Result = BaseObjectExpr;
+  for (llvm::SmallVector<FieldDecl *, 4>::reverse_iterator
+         FI = AnonFields.rbegin(), FIEnd = AnonFields.rend();
+       FI != FIEnd; ++FI) {
+    QualType MemberType = (*FI)->getType();
+    if (!(*FI)->isMutable()) {
+      unsigned combinedQualifiers 
+        = MemberType.getCVRQualifiers() | ExtraQuals;
+      MemberType = MemberType.getQualifiedType(combinedQualifiers);
+    }
+    Result = new (Context) MemberExpr(Result, BaseObjectIsPointer, *FI,
+                                      OpLoc, MemberType);
+    BaseObjectIsPointer = false;
+    ExtraQuals = Context.getCanonicalType(MemberType).getCVRQualifiers();
+  }
+
+  return Owned(Result);
+}
+
+/// ActOnDeclarationNameExpr - The parser has read some kind of name
+/// (e.g., a C++ id-expression (C++ [expr.prim]p1)). This routine
+/// performs lookup on that name and returns an expression that refers
+/// to that name. This routine isn't directly called from the parser,
+/// because the parser doesn't know about DeclarationName. Rather,
+/// this routine is called by ActOnIdentifierExpr,
+/// ActOnOperatorFunctionIdExpr, and ActOnConversionFunctionExpr,
+/// which form the DeclarationName from the corresponding syntactic
+/// forms.
+///
+/// HasTrailingLParen indicates whether this identifier is used in a
+/// function call context.  LookupCtx is only used for a C++
+/// qualified-id (foo::bar) to indicate the class or namespace that
+/// the identifier must be a member of.
+///
+/// isAddressOfOperand means that this expression is the direct operand
+/// of an address-of operator. This matters because this is the only
+/// situation where a qualified name referencing a non-static member may
+/// appear outside a member function of this class.
+Sema::OwningExprResult
+Sema::ActOnDeclarationNameExpr(Scope *S, SourceLocation Loc,
+                               DeclarationName Name, bool HasTrailingLParen,
+                               const CXXScopeSpec *SS, 
+                               bool isAddressOfOperand) {
+  // Could be enum-constant, value decl, instance variable, etc.
+  if (SS && SS->isInvalid())
+    return ExprError();
+
+  // C++ [temp.dep.expr]p3:
+  //   An id-expression is type-dependent if it contains:
+  //     -- a nested-name-specifier that contains a class-name that
+  //        names a dependent type.
+  // FIXME: Member of the current instantiation.
+  if (SS && isDependentScopeSpecifier(*SS)) {
+    return Owned(new (Context) UnresolvedDeclRefExpr(Name, Context.DependentTy,
+                                                     Loc, SS->getRange(), 
+                static_cast<NestedNameSpecifier *>(SS->getScopeRep())));
+  }
+
+  LookupResult Lookup = LookupParsedName(S, SS, Name, LookupOrdinaryName,
+                                         false, true, Loc);
+
+  if (Lookup.isAmbiguous()) {
+    DiagnoseAmbiguousLookup(Lookup, Name, Loc,
+                            SS && SS->isSet() ? SS->getRange()
+                                              : SourceRange());
+    return ExprError();
+  }
+  
+  NamedDecl *D = Lookup.getAsDecl();
+
+  // If this reference is in an Objective-C method, then ivar lookup happens as
+  // well.
+  IdentifierInfo *II = Name.getAsIdentifierInfo();
+  if (II && getCurMethodDecl()) {
+    // There are two cases to handle here.  1) scoped lookup could have failed,
+    // in which case we should look for an ivar.  2) scoped lookup could have
+    // found a decl, but that decl is outside the current instance method (i.e. 
+    // a global variable).  In these two cases, we do a lookup for an ivar with 
+    // this name, if the lookup sucedes, we replace it our current decl.
+    if (D == 0 || D->isDefinedOutsideFunctionOrMethod()) {
+      ObjCInterfaceDecl *IFace = getCurMethodDecl()->getClassInterface();
+      ObjCInterfaceDecl *ClassDeclared;
+      if (ObjCIvarDecl *IV = IFace->lookupInstanceVariable(Context, II, 
+                                                           ClassDeclared)) {
+        // Check if referencing a field with __attribute__((deprecated)).
+        if (DiagnoseUseOfDecl(IV, Loc))
+          return ExprError();
+        
+        // If we're referencing an invalid decl, just return this as a silent
+        // error node.  The error diagnostic was already emitted on the decl.
+        if (IV->isInvalidDecl())
+          return ExprError();
+        
+        bool IsClsMethod = getCurMethodDecl()->isClassMethod();
+        // If a class method attemps to use a free standing ivar, this is
+        // an error.
+        if (IsClsMethod && D && !D->isDefinedOutsideFunctionOrMethod())
+           return ExprError(Diag(Loc, diag::error_ivar_use_in_class_method)
+                           << IV->getDeclName());
+        // If a class method uses a global variable, even if an ivar with
+        // same name exists, use the global.
+        if (!IsClsMethod) {
+          if (IV->getAccessControl() == ObjCIvarDecl::Private &&
+              ClassDeclared != IFace)
+           Diag(Loc, diag::error_private_ivar_access) << IV->getDeclName();
+          // FIXME: This should use a new expr for a direct reference, don't
+          // turn this into Self->ivar, just return a BareIVarExpr or something.
+          IdentifierInfo &II = Context.Idents.get("self");
+          OwningExprResult SelfExpr = ActOnIdentifierExpr(S, Loc, II, false);
+          return Owned(new (Context) 
+                       ObjCIvarRefExpr(IV, IV->getType(), Loc, 
+                                       SelfExpr.takeAs<Expr>(), true, true));
+        }
+      }
+    }
+    else if (getCurMethodDecl()->isInstanceMethod()) {
+      // We should warn if a local variable hides an ivar.
+      ObjCInterfaceDecl *IFace = getCurMethodDecl()->getClassInterface();
+      ObjCInterfaceDecl *ClassDeclared;
+      if (ObjCIvarDecl *IV = IFace->lookupInstanceVariable(Context, II, 
+                                                           ClassDeclared)) {
+        if (IV->getAccessControl() != ObjCIvarDecl::Private ||
+            IFace == ClassDeclared)
+          Diag(Loc, diag::warn_ivar_use_hidden) << IV->getDeclName();
+      }
+    }
+    // Needed to implement property "super.method" notation.
+    if (D == 0 && II->isStr("super")) {
+      QualType T;
+      
+      if (getCurMethodDecl()->isInstanceMethod())
+        T = Context.getPointerType(Context.getObjCInterfaceType(
+                                   getCurMethodDecl()->getClassInterface()));
+      else
+        T = Context.getObjCClassType();
+      return Owned(new (Context) ObjCSuperExpr(Loc, T));
+    }
+  }
+
+  // Determine whether this name might be a candidate for
+  // argument-dependent lookup.
+  bool ADL = getLangOptions().CPlusPlus && (!SS || !SS->isSet()) && 
+             HasTrailingLParen;
+
+  if (ADL && D == 0) {
+    // We've seen something of the form
+    //
+    //   identifier(
+    //
+    // and we did not find any entity by the name
+    // "identifier". However, this identifier is still subject to
+    // argument-dependent lookup, so keep track of the name.
+    return Owned(new (Context) UnresolvedFunctionNameExpr(Name,
+                                                          Context.OverloadTy,
+                                                          Loc));
+  }
+
+  if (D == 0) {
+    // Otherwise, this could be an implicitly declared function reference (legal
+    // in C90, extension in C99).
+    if (HasTrailingLParen && II &&
+        !getLangOptions().CPlusPlus) // Not in C++.
+      D = ImplicitlyDefineFunction(Loc, *II, S);
+    else {
+      // If this name wasn't predeclared and if this is not a function call,
+      // diagnose the problem.
+      if (SS && !SS->isEmpty())
+        return ExprError(Diag(Loc, diag::err_typecheck_no_member)
+          << Name << SS->getRange());
+      else if (Name.getNameKind() == DeclarationName::CXXOperatorName ||
+               Name.getNameKind() == DeclarationName::CXXConversionFunctionName)
+        return ExprError(Diag(Loc, diag::err_undeclared_use)
+          << Name.getAsString());
+      else
+        return ExprError(Diag(Loc, diag::err_undeclared_var_use) << Name);
+    }
+  }
+
+  // If this is an expression of the form &Class::member, don't build an
+  // implicit member ref, because we want a pointer to the member in general,
+  // not any specific instance's member.
+  if (isAddressOfOperand && SS && !SS->isEmpty() && !HasTrailingLParen) {
+    DeclContext *DC = computeDeclContext(*SS);
+    if (D && isa<CXXRecordDecl>(DC)) {
+      QualType DType;
+      if (FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
+        DType = FD->getType().getNonReferenceType();
+      } else if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
+        DType = Method->getType();
+      } else if (isa<OverloadedFunctionDecl>(D)) {
+        DType = Context.OverloadTy;
+      }
+      // Could be an inner type. That's diagnosed below, so ignore it here.
+      if (!DType.isNull()) {
+        // The pointer is type- and value-dependent if it points into something
+        // dependent.
+        bool Dependent = DC->isDependentContext();
+        return Owned(BuildDeclRefExpr(D, DType, Loc, Dependent, Dependent, SS));
+      }
+    }
+  }
+
+  // We may have found a field within an anonymous union or struct
+  // (C++ [class.union]).
+  if (FieldDecl *FD = dyn_cast<FieldDecl>(D))
+    if (cast<RecordDecl>(FD->getDeclContext())->isAnonymousStructOrUnion())
+      return BuildAnonymousStructUnionMemberReference(Loc, FD);
+
+  if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(CurContext)) {
+    if (!MD->isStatic()) {
+      // C++ [class.mfct.nonstatic]p2: 
+      //   [...] if name lookup (3.4.1) resolves the name in the
+      //   id-expression to a nonstatic nontype member of class X or of
+      //   a base class of X, the id-expression is transformed into a
+      //   class member access expression (5.2.5) using (*this) (9.3.2)
+      //   as the postfix-expression to the left of the '.' operator.
+      DeclContext *Ctx = 0;
+      QualType MemberType;
+      if (FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
+        Ctx = FD->getDeclContext();
+        MemberType = FD->getType();
+
+        if (const ReferenceType *RefType = MemberType->getAsReferenceType())
+          MemberType = RefType->getPointeeType();
+        else if (!FD->isMutable()) {
+          unsigned combinedQualifiers 
+            = MemberType.getCVRQualifiers() | MD->getTypeQualifiers();
+          MemberType = MemberType.getQualifiedType(combinedQualifiers);
+        }
+      } else if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
+        if (!Method->isStatic()) {
+          Ctx = Method->getParent();
+          MemberType = Method->getType();
+        }
+      } else if (OverloadedFunctionDecl *Ovl 
+                   = dyn_cast<OverloadedFunctionDecl>(D)) {
+        for (OverloadedFunctionDecl::function_iterator 
+               Func = Ovl->function_begin(),
+               FuncEnd = Ovl->function_end();
+             Func != FuncEnd; ++Func) {
+          if (CXXMethodDecl *DMethod = dyn_cast<CXXMethodDecl>(*Func))
+            if (!DMethod->isStatic()) {
+              Ctx = Ovl->getDeclContext();
+              MemberType = Context.OverloadTy;
+              break;
+            }
+        }
+      }
+
+      if (Ctx && Ctx->isRecord()) {
+        QualType CtxType = Context.getTagDeclType(cast<CXXRecordDecl>(Ctx));
+        QualType ThisType = Context.getTagDeclType(MD->getParent());
+        if ((Context.getCanonicalType(CtxType) 
+               == Context.getCanonicalType(ThisType)) ||
+            IsDerivedFrom(ThisType, CtxType)) {
+          // Build the implicit member access expression.
+          Expr *This = new (Context) CXXThisExpr(SourceLocation(),
+                                                 MD->getThisType(Context));
+          return Owned(new (Context) MemberExpr(This, true, D,
+                                                Loc, MemberType));
+        }
+      }
+    }
+  }
+
+  if (FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
+    if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(CurContext)) {
+      if (MD->isStatic())
+        // "invalid use of member 'x' in static member function"
+        return ExprError(Diag(Loc,diag::err_invalid_member_use_in_static_method)
+          << FD->getDeclName());
+    }
+
+    // Any other ways we could have found the field in a well-formed
+    // program would have been turned into implicit member expressions
+    // above.
+    return ExprError(Diag(Loc, diag::err_invalid_non_static_member_use)
+      << FD->getDeclName());
+  }
+
+  if (isa<TypedefDecl>(D))
+    return ExprError(Diag(Loc, diag::err_unexpected_typedef) << Name);
+  if (isa<ObjCInterfaceDecl>(D))
+    return ExprError(Diag(Loc, diag::err_unexpected_interface) << Name);
+  if (isa<NamespaceDecl>(D))
+    return ExprError(Diag(Loc, diag::err_unexpected_namespace) << Name);
+
+  // Make the DeclRefExpr or BlockDeclRefExpr for the decl.
+  if (OverloadedFunctionDecl *Ovl = dyn_cast<OverloadedFunctionDecl>(D))
+    return Owned(BuildDeclRefExpr(Ovl, Context.OverloadTy, Loc,
+                                  false, false, SS));
+  else if (TemplateDecl *Template = dyn_cast<TemplateDecl>(D))
+    return Owned(BuildDeclRefExpr(Template, Context.OverloadTy, Loc,
+                                  false, false, SS));
+  ValueDecl *VD = cast<ValueDecl>(D);
+
+  // Check whether this declaration can be used. Note that we suppress
+  // this check when we're going to perform argument-dependent lookup
+  // on this function name, because this might not be the function
+  // that overload resolution actually selects.
+  if (!(ADL && isa<FunctionDecl>(VD)) && DiagnoseUseOfDecl(VD, Loc))
+    return ExprError();
+
+  if (VarDecl *Var = dyn_cast<VarDecl>(VD)) {
+    // Warn about constructs like:
+    //   if (void *X = foo()) { ... } else { X }.
+    // In the else block, the pointer is always false.
+
+    // FIXME: In a template instantiation, we don't have scope
+    // information to check this property.
+    if (Var->isDeclaredInCondition() && Var->getType()->isScalarType()) {
+      Scope *CheckS = S;
+      while (CheckS) {
+        if (CheckS->isWithinElse() && 
+            CheckS->getControlParent()->isDeclScope(DeclPtrTy::make(Var))) {
+          if (Var->getType()->isBooleanType())
+            ExprError(Diag(Loc, diag::warn_value_always_false)
+              << Var->getDeclName());
+          else
+            ExprError(Diag(Loc, diag::warn_value_always_zero)
+              << Var->getDeclName());
+          break;
+        }
+
+        // Move up one more control parent to check again.
+        CheckS = CheckS->getControlParent();
+        if (CheckS)
+          CheckS = CheckS->getParent();
+      }
+    }
+  } else if (FunctionDecl *Func = dyn_cast<FunctionDecl>(VD)) {
+    if (!getLangOptions().CPlusPlus && !Func->hasPrototype()) {
+      // C99 DR 316 says that, if a function type comes from a
+      // function definition (without a prototype), that type is only
+      // used for checking compatibility. Therefore, when referencing
+      // the function, we pretend that we don't have the full function
+      // type.
+      QualType T = Func->getType();
+      QualType NoProtoType = T;
+      if (const FunctionProtoType *Proto = T->getAsFunctionProtoType())
+        NoProtoType = Context.getFunctionNoProtoType(Proto->getResultType());
+      return Owned(BuildDeclRefExpr(VD, NoProtoType, Loc, false, false, SS));
+    }
+  }
+
+  // Only create DeclRefExpr's for valid Decl's.
+  if (VD->isInvalidDecl())
+    return ExprError();
+
+  // If the identifier reference is inside a block, and it refers to a value
+  // that is outside the block, create a BlockDeclRefExpr instead of a
+  // DeclRefExpr.  This ensures the value is treated as a copy-in snapshot when
+  // the block is formed.
+  //
+  // We do not do this for things like enum constants, global variables, etc,
+  // as they do not get snapshotted.
+  //
+  if (CurBlock && ShouldSnapshotBlockValueReference(CurBlock, VD)) {
+    QualType ExprTy = VD->getType().getNonReferenceType();
+    // The BlocksAttr indicates the variable is bound by-reference.
+    if (VD->getAttr<BlocksAttr>())
+      return Owned(new (Context) BlockDeclRefExpr(VD, ExprTy, Loc, true));
+
+    // Variable will be bound by-copy, make it const within the closure.
+    ExprTy.addConst();
+    return Owned(new (Context) BlockDeclRefExpr(VD, ExprTy, Loc, false));
+  }
+  // If this reference is not in a block or if the referenced variable is
+  // within the block, create a normal DeclRefExpr.
+
+  bool TypeDependent = false;
+  bool ValueDependent = false;
+  if (getLangOptions().CPlusPlus) {
+    // C++ [temp.dep.expr]p3:
+    //   An id-expression is type-dependent if it contains:   
+    //     - an identifier that was declared with a dependent type,
+    if (VD->getType()->isDependentType())
+      TypeDependent = true;
+    //     - FIXME: a template-id that is dependent,
+    //     - a conversion-function-id that specifies a dependent type,
+    else if (Name.getNameKind() == DeclarationName::CXXConversionFunctionName &&
+             Name.getCXXNameType()->isDependentType())
+      TypeDependent = true;
+    //     - a nested-name-specifier that contains a class-name that
+    //       names a dependent type.
+    else if (SS && !SS->isEmpty()) {
+      for (DeclContext *DC = computeDeclContext(*SS);
+           DC; DC = DC->getParent()) {
+        // FIXME: could stop early at namespace scope.
+        if (DC->isRecord()) {
+          CXXRecordDecl *Record = cast<CXXRecordDecl>(DC);
+          if (Context.getTypeDeclType(Record)->isDependentType()) {
+            TypeDependent = true;
+            break;
+          }
+        }
+      }
+    }
+
+    // C++ [temp.dep.constexpr]p2:
+    //
+    //   An identifier is value-dependent if it is:
+    //     - a name declared with a dependent type,
+    if (TypeDependent)
+      ValueDependent = true;
+    //     - the name of a non-type template parameter,
+    else if (isa<NonTypeTemplateParmDecl>(VD))
+      ValueDependent = true;
+    //    - a constant with integral or enumeration type and is
+    //      initialized with an expression that is value-dependent
+    //      (FIXME!).
+  }
+
+  return Owned(BuildDeclRefExpr(VD, VD->getType().getNonReferenceType(), Loc,
+                                TypeDependent, ValueDependent, SS));
+}
+
+Sema::OwningExprResult Sema::ActOnPredefinedExpr(SourceLocation Loc,
+                                                 tok::TokenKind Kind) {
+  PredefinedExpr::IdentType IT;
+
+  switch (Kind) {
+  default: assert(0 && "Unknown simple primary expr!");
+  case tok::kw___func__: IT = PredefinedExpr::Func; break; // [C99 6.4.2.2]
+  case tok::kw___FUNCTION__: IT = PredefinedExpr::Function; break;
+  case tok::kw___PRETTY_FUNCTION__: IT = PredefinedExpr::PrettyFunction; break;
+  }
+
+  // Pre-defined identifiers are of type char[x], where x is the length of the
+  // string.
+  unsigned Length;
+  if (FunctionDecl *FD = getCurFunctionDecl())
+    Length = FD->getIdentifier()->getLength();
+  else if (ObjCMethodDecl *MD = getCurMethodDecl())
+    Length = MD->getSynthesizedMethodSize();
+  else {
+    Diag(Loc, diag::ext_predef_outside_function);
+    // __PRETTY_FUNCTION__ -> "top level", the others produce an empty string.
+    Length = IT == PredefinedExpr::PrettyFunction ? strlen("top level") : 0;
+  }
+
+
+  llvm::APInt LengthI(32, Length + 1);
+  QualType ResTy = Context.CharTy.getQualifiedType(QualType::Const);
+  ResTy = Context.getConstantArrayType(ResTy, LengthI, ArrayType::Normal, 0);
+  return Owned(new (Context) PredefinedExpr(Loc, ResTy, IT));
+}
+
+Sema::OwningExprResult Sema::ActOnCharacterConstant(const Token &Tok) {
+  llvm::SmallString<16> CharBuffer;
+  CharBuffer.resize(Tok.getLength());
+  const char *ThisTokBegin = &CharBuffer[0];
+  unsigned ActualLength = PP.getSpelling(Tok, ThisTokBegin);
+
+  CharLiteralParser Literal(ThisTokBegin, ThisTokBegin+ActualLength,
+                            Tok.getLocation(), PP);
+  if (Literal.hadError())
+    return ExprError();
+
+  QualType type = getLangOptions().CPlusPlus ? Context.CharTy : Context.IntTy;
+
+  return Owned(new (Context) CharacterLiteral(Literal.getValue(),
+                                              Literal.isWide(),
+                                              type, Tok.getLocation()));
+}
+
+Action::OwningExprResult Sema::ActOnNumericConstant(const Token &Tok) {
+  // Fast path for a single digit (which is quite common).  A single digit
+  // cannot have a trigraph, escaped newline, radix prefix, or type suffix.
+  if (Tok.getLength() == 1) {
+    const char Val = PP.getSpellingOfSingleCharacterNumericConstant(Tok);
+    unsigned IntSize = Context.Target.getIntWidth();
+    return Owned(new (Context) IntegerLiteral(llvm::APInt(IntSize, Val-'0'),
+                    Context.IntTy, Tok.getLocation()));
+  }
+
+  llvm::SmallString<512> IntegerBuffer;
+  // Add padding so that NumericLiteralParser can overread by one character.
+  IntegerBuffer.resize(Tok.getLength()+1);
+  const char *ThisTokBegin = &IntegerBuffer[0];
+
+  // Get the spelling of the token, which eliminates trigraphs, etc.
+  unsigned ActualLength = PP.getSpelling(Tok, ThisTokBegin);
+
+  NumericLiteralParser Literal(ThisTokBegin, ThisTokBegin+ActualLength, 
+                               Tok.getLocation(), PP);
+  if (Literal.hadError)
+    return ExprError();
+
+  Expr *Res;
+
+  if (Literal.isFloatingLiteral()) {
+    QualType Ty;
+    if (Literal.isFloat)
+      Ty = Context.FloatTy;
+    else if (!Literal.isLong)
+      Ty = Context.DoubleTy;
+    else
+      Ty = Context.LongDoubleTy;
+
+    const llvm::fltSemantics &Format = Context.getFloatTypeSemantics(Ty);
+
+    // isExact will be set by GetFloatValue().
+    bool isExact = false;
+    Res = new (Context) FloatingLiteral(Literal.GetFloatValue(Format, &isExact),
+                                        &isExact, Ty, Tok.getLocation());
+
+  } else if (!Literal.isIntegerLiteral()) {
+    return ExprError();
+  } else {
+    QualType Ty;
+
+    // long long is a C99 feature.
+    if (!getLangOptions().C99 && !getLangOptions().CPlusPlus0x &&
+        Literal.isLongLong)
+      Diag(Tok.getLocation(), diag::ext_longlong);
+
+    // Get the value in the widest-possible width.
+    llvm::APInt ResultVal(Context.Target.getIntMaxTWidth(), 0);
+
+    if (Literal.GetIntegerValue(ResultVal)) {
+      // If this value didn't fit into uintmax_t, warn and force to ull.
+      Diag(Tok.getLocation(), diag::warn_integer_too_large);
+      Ty = Context.UnsignedLongLongTy;
+      assert(Context.getTypeSize(Ty) == ResultVal.getBitWidth() &&
+             "long long is not intmax_t?");
+    } else {
+      // If this value fits into a ULL, try to figure out what else it fits into
+      // according to the rules of C99 6.4.4.1p5.
+
+      // Octal, Hexadecimal, and integers with a U suffix are allowed to
+      // be an unsigned int.
+      bool AllowUnsigned = Literal.isUnsigned || Literal.getRadix() != 10;
+
+      // Check from smallest to largest, picking the smallest type we can.
+      unsigned Width = 0;
+      if (!Literal.isLong && !Literal.isLongLong) {
+        // Are int/unsigned possibilities?
+        unsigned IntSize = Context.Target.getIntWidth();
+
+        // Does it fit in a unsigned int?
+        if (ResultVal.isIntN(IntSize)) {
+          // Does it fit in a signed int?
+          if (!Literal.isUnsigned && ResultVal[IntSize-1] == 0)
+            Ty = Context.IntTy;
+          else if (AllowUnsigned)
+            Ty = Context.UnsignedIntTy;
+          Width = IntSize;
+        }
+      }
+
+      // Are long/unsigned long possibilities?
+      if (Ty.isNull() && !Literal.isLongLong) {
+        unsigned LongSize = Context.Target.getLongWidth();
+
+        // Does it fit in a unsigned long?
+        if (ResultVal.isIntN(LongSize)) {
+          // Does it fit in a signed long?
+          if (!Literal.isUnsigned && ResultVal[LongSize-1] == 0)
+            Ty = Context.LongTy;
+          else if (AllowUnsigned)
+            Ty = Context.UnsignedLongTy;
+          Width = LongSize;
+        }
+      }
+
+      // Finally, check long long if needed.
+      if (Ty.isNull()) {
+        unsigned LongLongSize = Context.Target.getLongLongWidth();
+
+        // Does it fit in a unsigned long long?
+        if (ResultVal.isIntN(LongLongSize)) {
+          // Does it fit in a signed long long?
+          if (!Literal.isUnsigned && ResultVal[LongLongSize-1] == 0)
+            Ty = Context.LongLongTy;
+          else if (AllowUnsigned)
+            Ty = Context.UnsignedLongLongTy;
+          Width = LongLongSize;
+        }
+      }
+
+      // If we still couldn't decide a type, we probably have something that
+      // does not fit in a signed long long, but has no U suffix.
+      if (Ty.isNull()) {
+        Diag(Tok.getLocation(), diag::warn_integer_too_large_for_signed);
+        Ty = Context.UnsignedLongLongTy;
+        Width = Context.Target.getLongLongWidth();
+      }
+
+      if (ResultVal.getBitWidth() != Width)
+        ResultVal.trunc(Width);
+    }
+    Res = new (Context) IntegerLiteral(ResultVal, Ty, Tok.getLocation());
+  }
+
+  // If this is an imaginary literal, create the ImaginaryLiteral wrapper.
+  if (Literal.isImaginary)
+    Res = new (Context) ImaginaryLiteral(Res, 
+                                        Context.getComplexType(Res->getType()));
+
+  return Owned(Res);
+}
+
+Action::OwningExprResult Sema::ActOnParenExpr(SourceLocation L,
+                                              SourceLocation R, ExprArg Val) {
+  Expr *E = Val.takeAs<Expr>();
+  assert((E != 0) && "ActOnParenExpr() missing expr");
+  return Owned(new (Context) ParenExpr(L, R, E));
+}
+
+/// The UsualUnaryConversions() function is *not* called by this routine.
+/// See C99 6.3.2.1p[2-4] for more details.
+bool Sema::CheckSizeOfAlignOfOperand(QualType exprType,
+                                     SourceLocation OpLoc,
+                                     const SourceRange &ExprRange,
+                                     bool isSizeof) {
+  if (exprType->isDependentType())
+    return false;
+
+  // C99 6.5.3.4p1:
+  if (isa<FunctionType>(exprType)) {
+    // alignof(function) is allowed as an extension.
+    if (isSizeof)
+      Diag(OpLoc, diag::ext_sizeof_function_type) << ExprRange;
+    return false;
+  }
+  
+  // Allow sizeof(void)/alignof(void) as an extension.
+  if (exprType->isVoidType()) {
+    Diag(OpLoc, diag::ext_sizeof_void_type)
+      << (isSizeof ? "sizeof" : "__alignof") << ExprRange;
+    return false;
+  }
+  
+  if (RequireCompleteType(OpLoc, exprType,
+                          isSizeof ? diag::err_sizeof_incomplete_type : 
+                          diag::err_alignof_incomplete_type,
+                          ExprRange))
+    return true;
+  
+  // Reject sizeof(interface) and sizeof(interface<proto>) in 64-bit mode.
+  if (LangOpts.ObjCNonFragileABI && exprType->isObjCInterfaceType()) {
+    Diag(OpLoc, diag::err_sizeof_nonfragile_interface)
+      << exprType << isSizeof << ExprRange;
+    return true;
+  }
+    
+  return false;
+}
+
+bool Sema::CheckAlignOfExpr(Expr *E, SourceLocation OpLoc,
+                            const SourceRange &ExprRange) {
+  E = E->IgnoreParens();
+
+  // alignof decl is always ok. 
+  if (isa<DeclRefExpr>(E))
+    return false;
+
+  // Cannot know anything else if the expression is dependent.
+  if (E->isTypeDependent())
+    return false;
+
+  if (E->getBitField()) {
+    Diag(OpLoc, diag::err_sizeof_alignof_bitfield) << 1 << ExprRange;
+    return true;
+  }
+
+  // Alignment of a field access is always okay, so long as it isn't a
+  // bit-field.
+  if (MemberExpr *ME = dyn_cast<MemberExpr>(E))
+    if (dyn_cast<FieldDecl>(ME->getMemberDecl()))
+      return false;
+
+  return CheckSizeOfAlignOfOperand(E->getType(), OpLoc, ExprRange, false);
+}
+
+/// \brief Build a sizeof or alignof expression given a type operand.
+Action::OwningExprResult 
+Sema::CreateSizeOfAlignOfExpr(QualType T, SourceLocation OpLoc, 
+                              bool isSizeOf, SourceRange R) {
+  if (T.isNull())
+    return ExprError();
+
+  if (!T->isDependentType() &&
+      CheckSizeOfAlignOfOperand(T, OpLoc, R, isSizeOf))
+    return ExprError();
+
+  // C99 6.5.3.4p4: the type (an unsigned integer type) is size_t.
+  return Owned(new (Context) SizeOfAlignOfExpr(isSizeOf, T,
+                                               Context.getSizeType(), OpLoc,
+                                               R.getEnd()));
+}
+
+/// \brief Build a sizeof or alignof expression given an expression
+/// operand.
+Action::OwningExprResult 
+Sema::CreateSizeOfAlignOfExpr(Expr *E, SourceLocation OpLoc, 
+                              bool isSizeOf, SourceRange R) {
+  // Verify that the operand is valid.
+  bool isInvalid = false;
+  if (E->isTypeDependent()) {
+    // Delay type-checking for type-dependent expressions.
+  } else if (!isSizeOf) {
+    isInvalid = CheckAlignOfExpr(E, OpLoc, R);
+  } else if (E->getBitField()) {  // C99 6.5.3.4p1.
+    Diag(OpLoc, diag::err_sizeof_alignof_bitfield) << 0;
+    isInvalid = true;
+  } else {
+    isInvalid = CheckSizeOfAlignOfOperand(E->getType(), OpLoc, R, true);
+  }
+
+  if (isInvalid)
+    return ExprError();
+
+  // C99 6.5.3.4p4: the type (an unsigned integer type) is size_t.
+  return Owned(new (Context) SizeOfAlignOfExpr(isSizeOf, E,
+                                               Context.getSizeType(), OpLoc,
+                                               R.getEnd()));
+}
+
+/// ActOnSizeOfAlignOfExpr - Handle @c sizeof(type) and @c sizeof @c expr and
+/// the same for @c alignof and @c __alignof
+/// Note that the ArgRange is invalid if isType is false.
+Action::OwningExprResult
+Sema::ActOnSizeOfAlignOfExpr(SourceLocation OpLoc, bool isSizeof, bool isType,
+                             void *TyOrEx, const SourceRange &ArgRange) {
+  // If error parsing type, ignore.
+  if (TyOrEx == 0) return ExprError();
+
+  if (isType) {
+    QualType ArgTy = QualType::getFromOpaquePtr(TyOrEx);
+    return CreateSizeOfAlignOfExpr(ArgTy, OpLoc, isSizeof, ArgRange);
+  } 
+
+  // Get the end location.
+  Expr *ArgEx = (Expr *)TyOrEx;
+  Action::OwningExprResult Result
+    = CreateSizeOfAlignOfExpr(ArgEx, OpLoc, isSizeof, ArgEx->getSourceRange());
+
+  if (Result.isInvalid())
+    DeleteExpr(ArgEx);
+
+  return move(Result);
+}
+
+QualType Sema::CheckRealImagOperand(Expr *&V, SourceLocation Loc, bool isReal) {
+  if (V->isTypeDependent())
+    return Context.DependentTy;
+  
+  // These operators return the element type of a complex type.
+  if (const ComplexType *CT = V->getType()->getAsComplexType())
+    return CT->getElementType();
+  
+  // Otherwise they pass through real integer and floating point types here.
+  if (V->getType()->isArithmeticType())
+    return V->getType();
+  
+  // Reject anything else.
+  Diag(Loc, diag::err_realimag_invalid_type) << V->getType()
+    << (isReal ? "__real" : "__imag");
+  return QualType();
+}
+
+
+
+Action::OwningExprResult
+Sema::ActOnPostfixUnaryOp(Scope *S, SourceLocation OpLoc,
+                          tok::TokenKind Kind, ExprArg Input) {
+  Expr *Arg = (Expr *)Input.get();
+
+  UnaryOperator::Opcode Opc;
+  switch (Kind) {
+  default: assert(0 && "Unknown unary op!");
+  case tok::plusplus:   Opc = UnaryOperator::PostInc; break;
+  case tok::minusminus: Opc = UnaryOperator::PostDec; break;
+  }
+
+  if (getLangOptions().CPlusPlus &&
+      (Arg->getType()->isRecordType() || Arg->getType()->isEnumeralType())) {
+    // Which overloaded operator?
+    OverloadedOperatorKind OverOp =
+      (Opc == UnaryOperator::PostInc)? OO_PlusPlus : OO_MinusMinus;
+
+    // C++ [over.inc]p1:
+    //
+    //     [...] If the function is a member function with one
+    //     parameter (which shall be of type int) or a non-member
+    //     function with two parameters (the second of which shall be
+    //     of type int), it defines the postfix increment operator ++
+    //     for objects of that type. When the postfix increment is
+    //     called as a result of using the ++ operator, the int
+    //     argument will have value zero.
+    Expr *Args[2] = { 
+      Arg, 
+      new (Context) IntegerLiteral(llvm::APInt(Context.Target.getIntWidth(), 0, 
+                          /*isSigned=*/true), Context.IntTy, SourceLocation())
+    };
+
+    // Build the candidate set for overloading
+    OverloadCandidateSet CandidateSet;
+    AddOperatorCandidates(OverOp, S, OpLoc, Args, 2, CandidateSet);
+
+    // Perform overload resolution.
+    OverloadCandidateSet::iterator Best;
+    switch (BestViableFunction(CandidateSet, Best)) {
+    case OR_Success: {
+      // We found a built-in operator or an overloaded operator.
+      FunctionDecl *FnDecl = Best->Function;
+
+      if (FnDecl) {
+        // We matched an overloaded operator. Build a call to that
+        // operator.
+
+        // Convert the arguments.
+        if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FnDecl)) {
+          if (PerformObjectArgumentInitialization(Arg, Method))
+            return ExprError();
+        } else {
+          // Convert the arguments.
+          if (PerformCopyInitialization(Arg,
+                                        FnDecl->getParamDecl(0)->getType(),
+                                        "passing"))
+            return ExprError();
+        }
+
+        // Determine the result type
+        QualType ResultTy
+          = FnDecl->getType()->getAsFunctionType()->getResultType();
+        ResultTy = ResultTy.getNonReferenceType();
+
+        // Build the actual expression node.
+        Expr *FnExpr = new (Context) DeclRefExpr(FnDecl, FnDecl->getType(),
+                                                 SourceLocation());
+        UsualUnaryConversions(FnExpr);
+
+        Input.release();
+        Args[0] = Arg;
+        return Owned(new (Context) CXXOperatorCallExpr(Context, OverOp, FnExpr,
+                                                       Args, 2, ResultTy, 
+                                                       OpLoc));
+      } else {
+        // We matched a built-in operator. Convert the arguments, then
+        // break out so that we will build the appropriate built-in
+        // operator node.
+        if (PerformCopyInitialization(Arg, Best->BuiltinTypes.ParamTypes[0],
+                                      "passing"))
+          return ExprError();
+
+        break;
+      }
+    }
+
+    case OR_No_Viable_Function:
+      // No viable function; fall through to handling this as a
+      // built-in operator, which will produce an error message for us.
+      break;
+
+    case OR_Ambiguous:
+      Diag(OpLoc,  diag::err_ovl_ambiguous_oper)
+          << UnaryOperator::getOpcodeStr(Opc)
+          << Arg->getSourceRange();
+      PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
+      return ExprError();
+
+    case OR_Deleted:
+      Diag(OpLoc, diag::err_ovl_deleted_oper)
+        << Best->Function->isDeleted()
+        << UnaryOperator::getOpcodeStr(Opc)
+        << Arg->getSourceRange();
+      PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
+      return ExprError();
+    }
+
+    // Either we found no viable overloaded operator or we matched a
+    // built-in operator. In either case, fall through to trying to
+    // build a built-in operation.
+  }
+
+  QualType result = CheckIncrementDecrementOperand(Arg, OpLoc,
+                                                 Opc == UnaryOperator::PostInc);
+  if (result.isNull())
+    return ExprError();
+  Input.release();
+  return Owned(new (Context) UnaryOperator(Arg, Opc, result, OpLoc));
+}
+
+Action::OwningExprResult
+Sema::ActOnArraySubscriptExpr(Scope *S, ExprArg Base, SourceLocation LLoc,
+                              ExprArg Idx, SourceLocation RLoc) {
+  Expr *LHSExp = static_cast<Expr*>(Base.get()),
+       *RHSExp = static_cast<Expr*>(Idx.get());
+
+  if (getLangOptions().CPlusPlus &&
+      (LHSExp->isTypeDependent() || RHSExp->isTypeDependent())) {
+    Base.release();
+    Idx.release();
+    return Owned(new (Context) ArraySubscriptExpr(LHSExp, RHSExp,
+                                                  Context.DependentTy, RLoc));
+  }
+
+  if (getLangOptions().CPlusPlus && 
+      (LHSExp->getType()->isRecordType() ||
+       LHSExp->getType()->isEnumeralType() ||
+       RHSExp->getType()->isRecordType() ||
+       RHSExp->getType()->isEnumeralType())) {
+    // Add the appropriate overloaded operators (C++ [over.match.oper]) 
+    // to the candidate set.
+    OverloadCandidateSet CandidateSet;
+    Expr *Args[2] = { LHSExp, RHSExp };
+    AddOperatorCandidates(OO_Subscript, S, LLoc, Args, 2, CandidateSet,
+                          SourceRange(LLoc, RLoc));
+
+    // Perform overload resolution.
+    OverloadCandidateSet::iterator Best;
+    switch (BestViableFunction(CandidateSet, Best)) {
+    case OR_Success: {
+      // We found a built-in operator or an overloaded operator.
+      FunctionDecl *FnDecl = Best->Function;
+
+      if (FnDecl) {
+        // We matched an overloaded operator. Build a call to that
+        // operator.
+
+        // Convert the arguments.
+        if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FnDecl)) {
+          if (PerformObjectArgumentInitialization(LHSExp, Method) ||
+              PerformCopyInitialization(RHSExp, 
+                                        FnDecl->getParamDecl(0)->getType(),
+                                        "passing"))
+            return ExprError();
+        } else {
+          // Convert the arguments.
+          if (PerformCopyInitialization(LHSExp,
+                                        FnDecl->getParamDecl(0)->getType(),
+                                        "passing") ||
+              PerformCopyInitialization(RHSExp,
+                                        FnDecl->getParamDecl(1)->getType(),
+                                        "passing"))
+            return ExprError();
+        }
+
+        // Determine the result type
+        QualType ResultTy
+          = FnDecl->getType()->getAsFunctionType()->getResultType();
+        ResultTy = ResultTy.getNonReferenceType();
+
+        // Build the actual expression node.
+        Expr *FnExpr = new (Context) DeclRefExpr(FnDecl, FnDecl->getType(),
+                                                 SourceLocation());
+        UsualUnaryConversions(FnExpr);
+
+        Base.release();
+        Idx.release();
+        Args[0] = LHSExp;
+        Args[1] = RHSExp;
+        return Owned(new (Context) CXXOperatorCallExpr(Context, OO_Subscript,
+                                                       FnExpr, Args, 2, 
+                                                       ResultTy, LLoc));
+      } else {
+        // We matched a built-in operator. Convert the arguments, then
+        // break out so that we will build the appropriate built-in
+        // operator node.
+        if (PerformCopyInitialization(LHSExp, Best->BuiltinTypes.ParamTypes[0],
+                                      "passing") ||
+            PerformCopyInitialization(RHSExp, Best->BuiltinTypes.ParamTypes[1],
+                                      "passing"))
+          return ExprError();
+
+        break;
+      }
+    }
+
+    case OR_No_Viable_Function:
+      // No viable function; fall through to handling this as a
+      // built-in operator, which will produce an error message for us.
+      break;
+
+    case OR_Ambiguous:
+      Diag(LLoc,  diag::err_ovl_ambiguous_oper)
+          << "[]"
+          << LHSExp->getSourceRange() << RHSExp->getSourceRange();
+      PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
+      return ExprError();
+
+    case OR_Deleted:
+      Diag(LLoc, diag::err_ovl_deleted_oper)
+        << Best->Function->isDeleted()
+        << "[]"
+        << LHSExp->getSourceRange() << RHSExp->getSourceRange();
+      PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
+      return ExprError();
+    }
+
+    // Either we found no viable overloaded operator or we matched a
+    // built-in operator. In either case, fall through to trying to
+    // build a built-in operation.
+  }
+
+  // Perform default conversions.
+  DefaultFunctionArrayConversion(LHSExp);
+  DefaultFunctionArrayConversion(RHSExp);
+
+  QualType LHSTy = LHSExp->getType(), RHSTy = RHSExp->getType();
+
+  // C99 6.5.2.1p2: the expression e1[e2] is by definition precisely equivalent
+  // to the expression *((e1)+(e2)). This means the array "Base" may actually be
+  // in the subscript position. As a result, we need to derive the array base
+  // and index from the expression types.
+  Expr *BaseExpr, *IndexExpr;
+  QualType ResultType;
+  if (LHSTy->isDependentType() || RHSTy->isDependentType()) {
+    BaseExpr = LHSExp;
+    IndexExpr = RHSExp;
+    ResultType = Context.DependentTy;
+  } else if (const PointerType *PTy = LHSTy->getAsPointerType()) {
+    BaseExpr = LHSExp;
+    IndexExpr = RHSExp;
+    ResultType = PTy->getPointeeType();
+  } else if (const PointerType *PTy = RHSTy->getAsPointerType()) {
+     // Handle the uncommon case of "123[Ptr]".
+    BaseExpr = RHSExp;
+    IndexExpr = LHSExp;
+    ResultType = PTy->getPointeeType();
+  } else if (const VectorType *VTy = LHSTy->getAsVectorType()) {
+    BaseExpr = LHSExp;    // vectors: V[123]
+    IndexExpr = RHSExp;
+
+    // FIXME: need to deal with const...
+    ResultType = VTy->getElementType();
+  } else if (LHSTy->isArrayType()) {
+    // If we see an array that wasn't promoted by
+    // DefaultFunctionArrayConversion, it must be an array that
+    // wasn't promoted because of the C90 rule that doesn't
+    // allow promoting non-lvalue arrays.  Warn, then
+    // force the promotion here.
+    Diag(LHSExp->getLocStart(), diag::ext_subscript_non_lvalue) <<
+        LHSExp->getSourceRange();
+    ImpCastExprToType(LHSExp, Context.getArrayDecayedType(LHSTy));
+    LHSTy = LHSExp->getType();
+
+    BaseExpr = LHSExp;
+    IndexExpr = RHSExp;
+    ResultType = LHSTy->getAsPointerType()->getPointeeType();
+  } else if (RHSTy->isArrayType()) {
+    // Same as previous, except for 123[f().a] case
+    Diag(RHSExp->getLocStart(), diag::ext_subscript_non_lvalue) <<
+        RHSExp->getSourceRange();
+    ImpCastExprToType(RHSExp, Context.getArrayDecayedType(RHSTy));
+    RHSTy = RHSExp->getType();
+
+    BaseExpr = RHSExp;
+    IndexExpr = LHSExp;
+    ResultType = RHSTy->getAsPointerType()->getPointeeType();
+  } else {
+    return ExprError(Diag(LLoc, diag::err_typecheck_subscript_value)
+       << LHSExp->getSourceRange() << RHSExp->getSourceRange());
+  }
+  // C99 6.5.2.1p1
+  if (!IndexExpr->getType()->isIntegerType() && !IndexExpr->isTypeDependent())
+    return ExprError(Diag(LLoc, diag::err_typecheck_subscript_not_integer)
+                     << IndexExpr->getSourceRange());
+
+  // C99 6.5.2.1p1: "shall have type "pointer to *object* type". Similarly,
+  // C++ [expr.sub]p1: The type "T" shall be a completely-defined object 
+  // type. Note that Functions are not objects, and that (in C99 parlance) 
+  // incomplete types are not object types.
+  if (ResultType->isFunctionType()) {
+    Diag(BaseExpr->getLocStart(), diag::err_subscript_function_type)
+      << ResultType << BaseExpr->getSourceRange();
+    return ExprError();
+  }
+  
+  if (!ResultType->isDependentType() &&
+      RequireCompleteType(LLoc, ResultType, diag::err_subscript_incomplete_type,
+                          BaseExpr->getSourceRange()))
+    return ExprError();
+  
+  // Diagnose bad cases where we step over interface counts.
+  if (ResultType->isObjCInterfaceType() && LangOpts.ObjCNonFragileABI) {
+    Diag(LLoc, diag::err_subscript_nonfragile_interface)
+      << ResultType << BaseExpr->getSourceRange();
+    return ExprError();
+  }
+  
+  Base.release();
+  Idx.release();
+  return Owned(new (Context) ArraySubscriptExpr(LHSExp, RHSExp,
+                                                ResultType, RLoc));
+}
+
+QualType Sema::
+CheckExtVectorComponent(QualType baseType, SourceLocation OpLoc,
+                        IdentifierInfo &CompName, SourceLocation CompLoc) {
+  const ExtVectorType *vecType = baseType->getAsExtVectorType();
+
+  // The vector accessor can't exceed the number of elements.
+  const char *compStr = CompName.getName();
+
+  // This flag determines whether or not the component is one of the four
+  // special names that indicate a subset of exactly half the elements are
+  // to be selected.
+  bool HalvingSwizzle = false;
+
+  // This flag determines whether or not CompName has an 's' char prefix,
+  // indicating that it is a string of hex values to be used as vector indices.
+  bool HexSwizzle = *compStr == 's';
+
+  // Check that we've found one of the special components, or that the component
+  // names must come from the same set.
+  if (!strcmp(compStr, "hi") || !strcmp(compStr, "lo") ||
+      !strcmp(compStr, "even") || !strcmp(compStr, "odd")) {
+    HalvingSwizzle = true;
+  } else if (vecType->getPointAccessorIdx(*compStr) != -1) {
+    do
+      compStr++;
+    while (*compStr && vecType->getPointAccessorIdx(*compStr) != -1);
+  } else if (HexSwizzle || vecType->getNumericAccessorIdx(*compStr) != -1) {
+    do
+      compStr++;
+    while (*compStr && vecType->getNumericAccessorIdx(*compStr) != -1);
+  }
+
+  if (!HalvingSwizzle && *compStr) {
+    // We didn't get to the end of the string. This means the component names
+    // didn't come from the same set *or* we encountered an illegal name.
+    Diag(OpLoc, diag::err_ext_vector_component_name_illegal)
+      << std::string(compStr,compStr+1) << SourceRange(CompLoc);
+    return QualType();
+  }
+
+  // Ensure no component accessor exceeds the width of the vector type it
+  // operates on.
+  if (!HalvingSwizzle) {
+    compStr = CompName.getName();
+
+    if (HexSwizzle)
+      compStr++;
+
+    while (*compStr) {
+      if (!vecType->isAccessorWithinNumElements(*compStr++)) {
+        Diag(OpLoc, diag::err_ext_vector_component_exceeds_length)
+          << baseType << SourceRange(CompLoc);
+        return QualType();
+      }
+    }
+  }
+
+  // If this is a halving swizzle, verify that the base type has an even
+  // number of elements.
+  if (HalvingSwizzle && (vecType->getNumElements() & 1U)) {
+    Diag(OpLoc, diag::err_ext_vector_component_requires_even)
+      << baseType << SourceRange(CompLoc);
+    return QualType();
+  }
+
+  // The component accessor looks fine - now we need to compute the actual type.
+  // The vector type is implied by the component accessor. For example,
+  // vec4.b is a float, vec4.xy is a vec2, vec4.rgb is a vec3, etc.
+  // vec4.s0 is a float, vec4.s23 is a vec3, etc.
+  // vec4.hi, vec4.lo, vec4.e, and vec4.o all return vec2.
+  unsigned CompSize = HalvingSwizzle ? vecType->getNumElements() / 2
+                                     : CompName.getLength();
+  if (HexSwizzle)
+    CompSize--;
+
+  if (CompSize == 1)
+    return vecType->getElementType();
+
+  QualType VT = Context.getExtVectorType(vecType->getElementType(), CompSize);
+  // Now look up the TypeDefDecl from the vector type. Without this,
+  // diagostics look bad. We want extended vector types to appear built-in.
+  for (unsigned i = 0, E = ExtVectorDecls.size(); i != E; ++i) {
+    if (ExtVectorDecls[i]->getUnderlyingType() == VT)
+      return Context.getTypedefType(ExtVectorDecls[i]);
+  }
+  return VT; // should never get here (a typedef type should always be found).
+}
+
+static Decl *FindGetterNameDeclFromProtocolList(const ObjCProtocolDecl*PDecl,
+                                                IdentifierInfo &Member,
+                                                const Selector &Sel,
+                                                ASTContext &Context) {
+  
+  if (ObjCPropertyDecl *PD = PDecl->FindPropertyDeclaration(Context, &Member))
+    return PD;
+  if (ObjCMethodDecl *OMD = PDecl->getInstanceMethod(Context, Sel))
+    return OMD;
+  
+  for (ObjCProtocolDecl::protocol_iterator I = PDecl->protocol_begin(),
+       E = PDecl->protocol_end(); I != E; ++I) {
+    if (Decl *D = FindGetterNameDeclFromProtocolList(*I, Member, Sel, 
+                                                     Context))
+      return D;
+  }
+  return 0;
+}
+
+static Decl *FindGetterNameDecl(const ObjCQualifiedIdType *QIdTy,
+                                IdentifierInfo &Member,
+                                const Selector &Sel,
+                                ASTContext &Context) {
+  // Check protocols on qualified interfaces.
+  Decl *GDecl = 0;
+  for (ObjCQualifiedIdType::qual_iterator I = QIdTy->qual_begin(),
+       E = QIdTy->qual_end(); I != E; ++I) {
+    if (ObjCPropertyDecl *PD = (*I)->FindPropertyDeclaration(Context, &Member)) {
+      GDecl = PD;
+      break;
+    }
+    // Also must look for a getter name which uses property syntax.
+    if (ObjCMethodDecl *OMD = (*I)->getInstanceMethod(Context, Sel)) {
+      GDecl = OMD;
+      break;
+    }
+  }
+  if (!GDecl) {
+    for (ObjCQualifiedIdType::qual_iterator I = QIdTy->qual_begin(),
+         E = QIdTy->qual_end(); I != E; ++I) {
+      // Search in the protocol-qualifier list of current protocol.
+      GDecl = FindGetterNameDeclFromProtocolList(*I, Member, Sel, Context);
+      if (GDecl)
+        return GDecl;
+    }
+  }
+  return GDecl;
+}
+
+/// FindMethodInNestedImplementations - Look up a method in current and
+/// all base class implementations.
+///
+ObjCMethodDecl *Sema::FindMethodInNestedImplementations(
+                                              const ObjCInterfaceDecl *IFace,
+                                              const Selector &Sel) {
+  ObjCMethodDecl *Method = 0;
+  if (ObjCImplementationDecl *ImpDecl 
+        = LookupObjCImplementation(IFace->getIdentifier()))
+    Method = ImpDecl->getInstanceMethod(Context, Sel);
+  
+  if (!Method && IFace->getSuperClass())
+    return FindMethodInNestedImplementations(IFace->getSuperClass(), Sel);
+  return Method;
+}
+
+Action::OwningExprResult
+Sema::ActOnMemberReferenceExpr(Scope *S, ExprArg Base, SourceLocation OpLoc,
+                               tok::TokenKind OpKind, SourceLocation MemberLoc,
+                               IdentifierInfo &Member,
+                               DeclPtrTy ObjCImpDecl) {
+  Expr *BaseExpr = Base.takeAs<Expr>();
+  assert(BaseExpr && "no record expression");
+
+  // Perform default conversions.
+  DefaultFunctionArrayConversion(BaseExpr);
+
+  QualType BaseType = BaseExpr->getType();
+  assert(!BaseType.isNull() && "no type for member expression");
+
+  // Get the type being accessed in BaseType.  If this is an arrow, the BaseExpr
+  // must have pointer type, and the accessed type is the pointee.
+  if (OpKind == tok::arrow) {
+    if (BaseType->isDependentType())
+      return Owned(new (Context) CXXUnresolvedMemberExpr(Context,
+                                                         BaseExpr, true, 
+                                                         OpLoc, 
+                                                     DeclarationName(&Member),
+                                                         MemberLoc));
+    else if (const PointerType *PT = BaseType->getAsPointerType())
+      BaseType = PT->getPointeeType();
+    else if (getLangOptions().CPlusPlus && BaseType->isRecordType())
+      return Owned(BuildOverloadedArrowExpr(S, BaseExpr, OpLoc,
+                                            MemberLoc, Member));
+    else
+      return ExprError(Diag(MemberLoc,
+                            diag::err_typecheck_member_reference_arrow)
+        << BaseType << BaseExpr->getSourceRange());
+  } else {
+    if (BaseType->isDependentType()) {
+      // Require that the base type isn't a pointer type 
+      // (so we'll report an error for)
+      // T* t;
+      // t.f;
+      // 
+      // In Obj-C++, however, the above expression is valid, since it could be
+      // accessing the 'f' property if T is an Obj-C interface. The extra check
+      // allows this, while still reporting an error if T is a struct pointer.
+      const PointerType *PT = BaseType->getAsPointerType();
+
+      if (!PT || (getLangOptions().ObjC1 && 
+                  !PT->getPointeeType()->isRecordType()))
+        return Owned(new (Context) CXXUnresolvedMemberExpr(Context,
+                                                           BaseExpr, false, 
+                                                           OpLoc, 
+                                                     DeclarationName(&Member),
+                                                           MemberLoc));
+    }
+  }
+
+  // Handle field access to simple records.  This also handles access to fields
+  // of the ObjC 'id' struct.
+  if (const RecordType *RTy = BaseType->getAsRecordType()) {
+    RecordDecl *RDecl = RTy->getDecl();
+    if (RequireCompleteType(OpLoc, BaseType,
+                               diag::err_typecheck_incomplete_tag,
+                               BaseExpr->getSourceRange()))
+      return ExprError();
+
+    // The record definition is complete, now make sure the member is valid.
+    // FIXME: Qualified name lookup for C++ is a bit more complicated than this.
+    LookupResult Result
+      = LookupQualifiedName(RDecl, DeclarationName(&Member),
+                            LookupMemberName, false);
+
+    if (!Result)
+      return ExprError(Diag(MemberLoc, diag::err_typecheck_no_member)
+               << &Member << BaseExpr->getSourceRange());
+    if (Result.isAmbiguous()) {
+      DiagnoseAmbiguousLookup(Result, DeclarationName(&Member),
+                              MemberLoc, BaseExpr->getSourceRange());
+      return ExprError();
+    }
+    
+    NamedDecl *MemberDecl = Result;
+
+    // If the decl being referenced had an error, return an error for this
+    // sub-expr without emitting another error, in order to avoid cascading
+    // error cases.
+    if (MemberDecl->isInvalidDecl())
+      return ExprError();
+
+    // Check the use of this field
+    if (DiagnoseUseOfDecl(MemberDecl, MemberLoc))
+      return ExprError();
+
+    if (FieldDecl *FD = dyn_cast<FieldDecl>(MemberDecl)) {
+      // We may have found a field within an anonymous union or struct
+      // (C++ [class.union]).
+      if (cast<RecordDecl>(FD->getDeclContext())->isAnonymousStructOrUnion())
+        return BuildAnonymousStructUnionMemberReference(MemberLoc, FD,
+                                                        BaseExpr, OpLoc);
+
+      // Figure out the type of the member; see C99 6.5.2.3p3, C++ [expr.ref]
+      // FIXME: Handle address space modifiers
+      QualType MemberType = FD->getType();
+      if (const ReferenceType *Ref = MemberType->getAsReferenceType())
+        MemberType = Ref->getPointeeType();
+      else {
+        unsigned combinedQualifiers =
+          MemberType.getCVRQualifiers() | BaseType.getCVRQualifiers();
+        if (FD->isMutable())
+          combinedQualifiers &= ~QualType::Const;
+        MemberType = MemberType.getQualifiedType(combinedQualifiers);
+      }
+
+      return Owned(new (Context) MemberExpr(BaseExpr, OpKind == tok::arrow, FD,
+                                            MemberLoc, MemberType));
+    }
+    
+    if (VarDecl *Var = dyn_cast<VarDecl>(MemberDecl))
+      return Owned(new (Context) MemberExpr(BaseExpr, OpKind == tok::arrow,
+                                            Var, MemberLoc,
+                                         Var->getType().getNonReferenceType()));
+    if (FunctionDecl *MemberFn = dyn_cast<FunctionDecl>(MemberDecl))
+      return Owned(new (Context) MemberExpr(BaseExpr, OpKind == tok::arrow,
+                                            MemberFn, MemberLoc,
+                                            MemberFn->getType()));
+    if (OverloadedFunctionDecl *Ovl
+          = dyn_cast<OverloadedFunctionDecl>(MemberDecl))
+      return Owned(new (Context) MemberExpr(BaseExpr, OpKind == tok::arrow, Ovl,
+                                            MemberLoc, Context.OverloadTy));
+    if (EnumConstantDecl *Enum = dyn_cast<EnumConstantDecl>(MemberDecl))
+      return Owned(new (Context) MemberExpr(BaseExpr, OpKind == tok::arrow,
+                                            Enum, MemberLoc, Enum->getType()));
+    if (isa<TypeDecl>(MemberDecl))
+      return ExprError(Diag(MemberLoc,diag::err_typecheck_member_reference_type)
+        << DeclarationName(&Member) << int(OpKind == tok::arrow));
+
+    // We found a declaration kind that we didn't expect. This is a
+    // generic error message that tells the user that she can't refer
+    // to this member with '.' or '->'.
+    return ExprError(Diag(MemberLoc,
+                          diag::err_typecheck_member_reference_unknown)
+      << DeclarationName(&Member) << int(OpKind == tok::arrow));
+  }
+
+  // Handle access to Objective-C instance variables, such as "Obj->ivar" and
+  // (*Obj).ivar.
+  if (const ObjCInterfaceType *IFTy = BaseType->getAsObjCInterfaceType()) {
+    ObjCInterfaceDecl *ClassDeclared;
+    if (ObjCIvarDecl *IV = IFTy->getDecl()->lookupInstanceVariable(Context,
+                                                                   &Member, 
+                                                             ClassDeclared)) {
+      // If the decl being referenced had an error, return an error for this
+      // sub-expr without emitting another error, in order to avoid cascading
+      // error cases.
+      if (IV->isInvalidDecl())
+        return ExprError();
+
+      // Check whether we can reference this field.
+      if (DiagnoseUseOfDecl(IV, MemberLoc))
+        return ExprError();
+      if (IV->getAccessControl() != ObjCIvarDecl::Public &&
+          IV->getAccessControl() != ObjCIvarDecl::Package) {
+        ObjCInterfaceDecl *ClassOfMethodDecl = 0;
+        if (ObjCMethodDecl *MD = getCurMethodDecl())
+          ClassOfMethodDecl =  MD->getClassInterface();
+        else if (ObjCImpDecl && getCurFunctionDecl()) {
+          // Case of a c-function declared inside an objc implementation.
+          // FIXME: For a c-style function nested inside an objc implementation
+          // class, there is no implementation context available, so we pass
+          // down the context as argument to this routine. Ideally, this context
+          // need be passed down in the AST node and somehow calculated from the
+          // AST for a function decl.
+          Decl *ImplDecl = ObjCImpDecl.getAs<Decl>();
+          if (ObjCImplementationDecl *IMPD = 
+              dyn_cast<ObjCImplementationDecl>(ImplDecl))
+            ClassOfMethodDecl = IMPD->getClassInterface();
+          else if (ObjCCategoryImplDecl* CatImplClass =
+                      dyn_cast<ObjCCategoryImplDecl>(ImplDecl))
+            ClassOfMethodDecl = CatImplClass->getClassInterface();
+        }
+        
+        if (IV->getAccessControl() == ObjCIvarDecl::Private) { 
+          if (ClassDeclared != IFTy->getDecl() || 
+              ClassOfMethodDecl != ClassDeclared)
+            Diag(MemberLoc, diag::error_private_ivar_access) << IV->getDeclName();
+        }
+        // @protected
+        else if (!IFTy->getDecl()->isSuperClassOf(ClassOfMethodDecl))
+          Diag(MemberLoc, diag::error_protected_ivar_access) << IV->getDeclName();
+      }
+
+      return Owned(new (Context) ObjCIvarRefExpr(IV, IV->getType(),
+                                                 MemberLoc, BaseExpr,
+                                                 OpKind == tok::arrow));
+    }
+    return ExprError(Diag(MemberLoc, diag::err_typecheck_member_reference_ivar)
+                       << IFTy->getDecl()->getDeclName() << &Member
+                       << BaseExpr->getSourceRange());
+  }
+
+  // Handle Objective-C property access, which is "Obj.property" where Obj is a
+  // pointer to a (potentially qualified) interface type.
+  const PointerType *PTy;
+  const ObjCInterfaceType *IFTy;
+  if (OpKind == tok::period && (PTy = BaseType->getAsPointerType()) &&
+      (IFTy = PTy->getPointeeType()->getAsObjCInterfaceType())) {
+    ObjCInterfaceDecl *IFace = IFTy->getDecl();
+
+    // Search for a declared property first.
+    if (ObjCPropertyDecl *PD = IFace->FindPropertyDeclaration(Context, 
+                                                              &Member)) {
+      // Check whether we can reference this property.
+      if (DiagnoseUseOfDecl(PD, MemberLoc))
+        return ExprError();
+      QualType ResTy = PD->getType();
+      Selector Sel = PP.getSelectorTable().getNullarySelector(&Member);
+      ObjCMethodDecl *Getter = IFace->lookupInstanceMethod(Context, Sel);
+      if (DiagnosePropertyAccessorMismatch(PD, Getter, MemberLoc))
+        ResTy = Getter->getResultType();
+      return Owned(new (Context) ObjCPropertyRefExpr(PD, ResTy,
+                                                     MemberLoc, BaseExpr));
+    }
+
+    // Check protocols on qualified interfaces.
+    for (ObjCInterfaceType::qual_iterator I = IFTy->qual_begin(),
+         E = IFTy->qual_end(); I != E; ++I)
+      if (ObjCPropertyDecl *PD = (*I)->FindPropertyDeclaration(Context,
+                                                               &Member)) {
+        // Check whether we can reference this property.
+        if (DiagnoseUseOfDecl(PD, MemberLoc))
+          return ExprError();
+
+        return Owned(new (Context) ObjCPropertyRefExpr(PD, PD->getType(),
+                                                       MemberLoc, BaseExpr));
+      }
+
+    // If that failed, look for an "implicit" property by seeing if the nullary
+    // selector is implemented.
+
+    // FIXME: The logic for looking up nullary and unary selectors should be
+    // shared with the code in ActOnInstanceMessage.
+
+    Selector Sel = PP.getSelectorTable().getNullarySelector(&Member);
+    ObjCMethodDecl *Getter = IFace->lookupInstanceMethod(Context, Sel);
+
+    // If this reference is in an @implementation, check for 'private' methods.
+    if (!Getter)
+      Getter = FindMethodInNestedImplementations(IFace, Sel);
+
+    // Look through local category implementations associated with the class.
+    if (!Getter) {
+      for (unsigned i = 0; i < ObjCCategoryImpls.size() && !Getter; i++) {
+        if (ObjCCategoryImpls[i]->getClassInterface() == IFace)
+          Getter = ObjCCategoryImpls[i]->getInstanceMethod(Context, Sel);
+      }
+    }
+    if (Getter) {
+      // Check if we can reference this property.
+      if (DiagnoseUseOfDecl(Getter, MemberLoc))
+        return ExprError();
+    }
+    // If we found a getter then this may be a valid dot-reference, we
+    // will look for the matching setter, in case it is needed.
+    Selector SetterSel = 
+      SelectorTable::constructSetterName(PP.getIdentifierTable(), 
+                                         PP.getSelectorTable(), &Member);
+    ObjCMethodDecl *Setter = IFace->lookupInstanceMethod(Context, SetterSel);
+    if (!Setter) {
+      // If this reference is in an @implementation, also check for 'private'
+      // methods.
+      Setter = FindMethodInNestedImplementations(IFace, SetterSel);
+    }
+    // Look through local category implementations associated with the class.
+    if (!Setter) {
+      for (unsigned i = 0; i < ObjCCategoryImpls.size() && !Setter; i++) {
+        if (ObjCCategoryImpls[i]->getClassInterface() == IFace)
+          Setter = ObjCCategoryImpls[i]->getInstanceMethod(Context, SetterSel);
+      }
+    }
+
+    if (Setter && DiagnoseUseOfDecl(Setter, MemberLoc))
+      return ExprError();
+
+    if (Getter || Setter) {
+      QualType PType;
+
+      if (Getter)
+        PType = Getter->getResultType();
+      else {
+        for (ObjCMethodDecl::param_iterator PI = Setter->param_begin(),
+             E = Setter->param_end(); PI != E; ++PI)
+          PType = (*PI)->getType();
+      }
+      // FIXME: we must check that the setter has property type.
+      return Owned(new (Context) ObjCKVCRefExpr(Getter, PType,
+                                      Setter, MemberLoc, BaseExpr));
+    }
+    return ExprError(Diag(MemberLoc, diag::err_property_not_found)
+      << &Member << BaseType);
+  }
+  // Handle properties on qualified "id" protocols.
+  const ObjCQualifiedIdType *QIdTy;
+  if (OpKind == tok::period && (QIdTy = BaseType->getAsObjCQualifiedIdType())) {
+    // Check protocols on qualified interfaces.
+    Selector Sel = PP.getSelectorTable().getNullarySelector(&Member);
+    if (Decl *PMDecl = FindGetterNameDecl(QIdTy, Member, Sel, Context)) {
+      if (ObjCPropertyDecl *PD = dyn_cast<ObjCPropertyDecl>(PMDecl)) {
+        // Check the use of this declaration
+        if (DiagnoseUseOfDecl(PD, MemberLoc))
+          return ExprError();
+        
+        return Owned(new (Context) ObjCPropertyRefExpr(PD, PD->getType(),
+                                                       MemberLoc, BaseExpr));
+      }
+      if (ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(PMDecl)) {
+        // Check the use of this method.
+        if (DiagnoseUseOfDecl(OMD, MemberLoc))
+          return ExprError();
+        
+        return Owned(new (Context) ObjCMessageExpr(BaseExpr, Sel,
+                                                   OMD->getResultType(), 
+                                                   OMD, OpLoc, MemberLoc, 
+                                                   NULL, 0));
+      }
+    }
+
+    return ExprError(Diag(MemberLoc, diag::err_property_not_found)
+                       << &Member << BaseType);
+  }
+  // Handle properties on ObjC 'Class' types.
+  if (OpKind == tok::period && (BaseType == Context.getObjCClassType())) {
+    // Also must look for a getter name which uses property syntax.
+    Selector Sel = PP.getSelectorTable().getNullarySelector(&Member);
+    if (ObjCMethodDecl *MD = getCurMethodDecl()) {
+      ObjCInterfaceDecl *IFace = MD->getClassInterface();
+      ObjCMethodDecl *Getter;
+      // FIXME: need to also look locally in the implementation.
+      if ((Getter = IFace->lookupClassMethod(Context, Sel))) {
+        // Check the use of this method.
+        if (DiagnoseUseOfDecl(Getter, MemberLoc))
+          return ExprError();
+      }
+      // If we found a getter then this may be a valid dot-reference, we
+      // will look for the matching setter, in case it is needed.
+      Selector SetterSel = 
+        SelectorTable::constructSetterName(PP.getIdentifierTable(), 
+                                           PP.getSelectorTable(), &Member);
+      ObjCMethodDecl *Setter = IFace->lookupClassMethod(Context, SetterSel);
+      if (!Setter) {
+        // If this reference is in an @implementation, also check for 'private'
+        // methods.
+        Setter = FindMethodInNestedImplementations(IFace, SetterSel);
+      }
+      // Look through local category implementations associated with the class.
+      if (!Setter) {
+        for (unsigned i = 0; i < ObjCCategoryImpls.size() && !Setter; i++) {
+          if (ObjCCategoryImpls[i]->getClassInterface() == IFace)
+            Setter = ObjCCategoryImpls[i]->getClassMethod(Context, SetterSel);
+        }
+      }
+
+      if (Setter && DiagnoseUseOfDecl(Setter, MemberLoc))
+        return ExprError();
+
+      if (Getter || Setter) {
+        QualType PType;
+
+        if (Getter)
+          PType = Getter->getResultType();
+        else {
+          for (ObjCMethodDecl::param_iterator PI = Setter->param_begin(),
+               E = Setter->param_end(); PI != E; ++PI)
+            PType = (*PI)->getType();
+        }
+        // FIXME: we must check that the setter has property type.
+        return Owned(new (Context) ObjCKVCRefExpr(Getter, PType,
+                                        Setter, MemberLoc, BaseExpr));
+      }
+      return ExprError(Diag(MemberLoc, diag::err_property_not_found)
+        << &Member << BaseType);
+    }
+  }
+  
+  // Handle 'field access' to vectors, such as 'V.xx'.
+  if (BaseType->isExtVectorType()) {
+    QualType ret = CheckExtVectorComponent(BaseType, OpLoc, Member, MemberLoc);
+    if (ret.isNull())
+      return ExprError();
+    return Owned(new (Context) ExtVectorElementExpr(ret, BaseExpr, Member,
+                                                    MemberLoc));
+  }
+
+  Diag(MemberLoc, diag::err_typecheck_member_reference_struct_union)
+    << BaseType << BaseExpr->getSourceRange();
+
+  // If the user is trying to apply -> or . to a function or function
+  // pointer, it's probably because they forgot parentheses to call
+  // the function. Suggest the addition of those parentheses.
+  if (BaseType == Context.OverloadTy || 
+      BaseType->isFunctionType() ||
+      (BaseType->isPointerType() && 
+       BaseType->getAsPointerType()->isFunctionType())) {
+    SourceLocation Loc = PP.getLocForEndOfToken(BaseExpr->getLocEnd());
+    Diag(Loc, diag::note_member_reference_needs_call)
+      << CodeModificationHint::CreateInsertion(Loc, "()");
+  }
+
+  return ExprError();
+}
+
+/// ConvertArgumentsForCall - Converts the arguments specified in
+/// Args/NumArgs to the parameter types of the function FDecl with
+/// function prototype Proto. Call is the call expression itself, and
+/// Fn is the function expression. For a C++ member function, this
+/// routine does not attempt to convert the object argument. Returns
+/// true if the call is ill-formed.
+bool
+Sema::ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
+                              FunctionDecl *FDecl,
+                              const FunctionProtoType *Proto,
+                              Expr **Args, unsigned NumArgs,
+                              SourceLocation RParenLoc) {
+  // C99 6.5.2.2p7 - the arguments are implicitly converted, as if by
+  // assignment, to the types of the corresponding parameter, ...
+  unsigned NumArgsInProto = Proto->getNumArgs();
+  unsigned NumArgsToCheck = NumArgs;
+  bool Invalid = false;
+
+  // If too few arguments are available (and we don't have default
+  // arguments for the remaining parameters), don't make the call.
+  if (NumArgs < NumArgsInProto) {
+    if (!FDecl || NumArgs < FDecl->getMinRequiredArguments())
+      return Diag(RParenLoc, diag::err_typecheck_call_too_few_args)
+        << Fn->getType()->isBlockPointerType() << Fn->getSourceRange();
+    // Use default arguments for missing arguments
+    NumArgsToCheck = NumArgsInProto;
+    Call->setNumArgs(Context, NumArgsInProto);
+  }
+
+  // If too many are passed and not variadic, error on the extras and drop
+  // them.
+  if (NumArgs > NumArgsInProto) {
+    if (!Proto->isVariadic()) {
+      Diag(Args[NumArgsInProto]->getLocStart(),
+           diag::err_typecheck_call_too_many_args)
+        << Fn->getType()->isBlockPointerType() << Fn->getSourceRange()
+        << SourceRange(Args[NumArgsInProto]->getLocStart(),
+                       Args[NumArgs-1]->getLocEnd());
+      // This deletes the extra arguments.
+      Call->setNumArgs(Context, NumArgsInProto);
+      Invalid = true;
+    }
+    NumArgsToCheck = NumArgsInProto;
+  }
+
+  // Continue to check argument types (even if we have too few/many args).
+  for (unsigned i = 0; i != NumArgsToCheck; i++) {
+    QualType ProtoArgType = Proto->getArgType(i);
+
+    Expr *Arg;
+    if (i < NumArgs) {
+      Arg = Args[i];
+
+      if (RequireCompleteType(Arg->getSourceRange().getBegin(),
+                              ProtoArgType,
+                              diag::err_call_incomplete_argument,
+                              Arg->getSourceRange()))
+        return true;
+
+      // Pass the argument.
+      if (PerformCopyInitialization(Arg, ProtoArgType, "passing"))
+        return true;
+    } else
+      // We already type-checked the argument, so we know it works.
+      Arg = new (Context) CXXDefaultArgExpr(FDecl->getParamDecl(i));
+    QualType ArgType = Arg->getType();
+
+    Call->setArg(i, Arg);
+  }
+
+  // If this is a variadic call, handle args passed through "...".
+  if (Proto->isVariadic()) {
+    VariadicCallType CallType = VariadicFunction;
+    if (Fn->getType()->isBlockPointerType())
+      CallType = VariadicBlock; // Block
+    else if (isa<MemberExpr>(Fn))
+      CallType = VariadicMethod;
+
+    // Promote the arguments (C99 6.5.2.2p7).
+    for (unsigned i = NumArgsInProto; i != NumArgs; i++) {
+      Expr *Arg = Args[i];
+      Invalid |= DefaultVariadicArgumentPromotion(Arg, CallType);
+      Call->setArg(i, Arg);
+    }
+  }
+
+  return Invalid;
+}
+
+/// ActOnCallExpr - Handle a call to Fn with the specified array of arguments.
+/// This provides the location of the left/right parens and a list of comma
+/// locations.
+Action::OwningExprResult
+Sema::ActOnCallExpr(Scope *S, ExprArg fn, SourceLocation LParenLoc,
+                    MultiExprArg args,
+                    SourceLocation *CommaLocs, SourceLocation RParenLoc) {
+  unsigned NumArgs = args.size();
+  Expr *Fn = fn.takeAs<Expr>();
+  Expr **Args = reinterpret_cast<Expr**>(args.release());
+  assert(Fn && "no function call expression");
+  FunctionDecl *FDecl = NULL;
+  NamedDecl *NDecl = NULL;
+  DeclarationName UnqualifiedName;
+
+  if (getLangOptions().CPlusPlus) {
+    // Determine whether this is a dependent call inside a C++ template,
+    // in which case we won't do any semantic analysis now.
+    // FIXME: Will need to cache the results of name lookup (including ADL) in
+    // Fn.
+    bool Dependent = false;
+    if (Fn->isTypeDependent())
+      Dependent = true;
+    else if (Expr::hasAnyTypeDependentArguments(Args, NumArgs))
+      Dependent = true;
+
+    if (Dependent)
+      return Owned(new (Context) CallExpr(Context, Fn, Args, NumArgs,
+                                          Context.DependentTy, RParenLoc));
+
+    // Determine whether this is a call to an object (C++ [over.call.object]).
+    if (Fn->getType()->isRecordType())
+      return Owned(BuildCallToObjectOfClassType(S, Fn, LParenLoc, Args, NumArgs,
+                                                CommaLocs, RParenLoc));
+
+    // Determine whether this is a call to a member function.
+    if (MemberExpr *MemExpr = dyn_cast<MemberExpr>(Fn->IgnoreParens()))
+      if (isa<OverloadedFunctionDecl>(MemExpr->getMemberDecl()) ||
+          isa<CXXMethodDecl>(MemExpr->getMemberDecl()))
+        return Owned(BuildCallToMemberFunction(S, Fn, LParenLoc, Args, NumArgs,
+                                               CommaLocs, RParenLoc));
+  }
+
+  // If we're directly calling a function, get the appropriate declaration.
+  DeclRefExpr *DRExpr = NULL;
+  Expr *FnExpr = Fn;
+  bool ADL = true;
+  while (true) {
+    if (ImplicitCastExpr *IcExpr = dyn_cast<ImplicitCastExpr>(FnExpr))
+      FnExpr = IcExpr->getSubExpr();
+    else if (ParenExpr *PExpr = dyn_cast<ParenExpr>(FnExpr)) {
+      // Parentheses around a function disable ADL
+      // (C++0x [basic.lookup.argdep]p1).
+      ADL = false;
+      FnExpr = PExpr->getSubExpr();
+    } else if (isa<UnaryOperator>(FnExpr) &&
+               cast<UnaryOperator>(FnExpr)->getOpcode()
+                 == UnaryOperator::AddrOf) {
+      FnExpr = cast<UnaryOperator>(FnExpr)->getSubExpr();
+    } else if ((DRExpr = dyn_cast<DeclRefExpr>(FnExpr))) {
+      // Qualified names disable ADL (C++0x [basic.lookup.argdep]p1).
+      ADL &= !isa<QualifiedDeclRefExpr>(DRExpr);
+      break;
+    } else if (UnresolvedFunctionNameExpr *DepName
+                 = dyn_cast<UnresolvedFunctionNameExpr>(FnExpr)) {
+      UnqualifiedName = DepName->getName();
+      break;
+    } else {
+      // Any kind of name that does not refer to a declaration (or
+      // set of declarations) disables ADL (C++0x [basic.lookup.argdep]p3).
+      ADL = false;
+      break;
+    }
+  }
+
+  OverloadedFunctionDecl *Ovl = 0;
+  if (DRExpr) {
+    FDecl = dyn_cast<FunctionDecl>(DRExpr->getDecl());
+    Ovl = dyn_cast<OverloadedFunctionDecl>(DRExpr->getDecl());
+    NDecl = dyn_cast<NamedDecl>(DRExpr->getDecl());
+  }
+
+  if (Ovl || (getLangOptions().CPlusPlus && (FDecl || UnqualifiedName))) {
+    // We don't perform ADL for implicit declarations of builtins.
+    if (FDecl && FDecl->getBuiltinID(Context) && FDecl->isImplicit())
+      ADL = false;
+
+    // We don't perform ADL in C.
+    if (!getLangOptions().CPlusPlus)
+      ADL = false;
+
+    if (Ovl || ADL) {
+      FDecl = ResolveOverloadedCallFn(Fn, DRExpr? DRExpr->getDecl() : 0,
+                                      UnqualifiedName, LParenLoc, Args,
+                                      NumArgs, CommaLocs, RParenLoc, ADL);
+      if (!FDecl)
+        return ExprError();
+
+      // Update Fn to refer to the actual function selected.
+      Expr *NewFn = 0;
+      if (QualifiedDeclRefExpr *QDRExpr
+            = dyn_cast_or_null<QualifiedDeclRefExpr>(DRExpr))
+        NewFn = new (Context) QualifiedDeclRefExpr(FDecl, FDecl->getType(),
+                                                   QDRExpr->getLocation(),
+                                                   false, false,
+                                                 QDRExpr->getQualifierRange(),
+                                                   QDRExpr->getQualifier());
+      else
+        NewFn = new (Context) DeclRefExpr(FDecl, FDecl->getType(),
+                                          Fn->getSourceRange().getBegin());
+      Fn->Destroy(Context);
+      Fn = NewFn;
+    }
+  }
+
+  // Promote the function operand.
+  UsualUnaryConversions(Fn);
+
+  // Make the call expr early, before semantic checks.  This guarantees cleanup
+  // of arguments and function on error.
+  ExprOwningPtr<CallExpr> TheCall(this, new (Context) CallExpr(Context, Fn,
+                                                               Args, NumArgs,
+                                                               Context.BoolTy,
+                                                               RParenLoc));
+
+  const FunctionType *FuncT;
+  if (!Fn->getType()->isBlockPointerType()) {
+    // C99 6.5.2.2p1 - "The expression that denotes the called function shall
+    // have type pointer to function".
+    const PointerType *PT = Fn->getType()->getAsPointerType();
+    if (PT == 0)
+      return ExprError(Diag(LParenLoc, diag::err_typecheck_call_not_function)
+        << Fn->getType() << Fn->getSourceRange());
+    FuncT = PT->getPointeeType()->getAsFunctionType();
+  } else { // This is a block call.
+    FuncT = Fn->getType()->getAsBlockPointerType()->getPointeeType()->
+                getAsFunctionType();
+  }
+  if (FuncT == 0)
+    return ExprError(Diag(LParenLoc, diag::err_typecheck_call_not_function)
+      << Fn->getType() << Fn->getSourceRange());
+
+  // Check for a valid return type
+  if (!FuncT->getResultType()->isVoidType() &&
+      RequireCompleteType(Fn->getSourceRange().getBegin(),
+                          FuncT->getResultType(),
+                          diag::err_call_incomplete_return,
+                          TheCall->getSourceRange()))
+    return ExprError();
+
+  // We know the result type of the call, set it.
+  TheCall->setType(FuncT->getResultType().getNonReferenceType());
+
+  if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FuncT)) {
+    if (ConvertArgumentsForCall(&*TheCall, Fn, FDecl, Proto, Args, NumArgs,
+                                RParenLoc))
+      return ExprError();
+  } else {
+    assert(isa<FunctionNoProtoType>(FuncT) && "Unknown FunctionType!");
+
+    if (FDecl) {
+      // Check if we have too few/too many template arguments, based
+      // on our knowledge of the function definition.
+      const FunctionDecl *Def = 0;
+      if (FDecl->getBody(Context, Def) && NumArgs != Def->param_size()) {
+        const FunctionProtoType *Proto =
+            Def->getType()->getAsFunctionProtoType();
+        if (!Proto || !(Proto->isVariadic() && NumArgs >= Def->param_size())) {
+          Diag(RParenLoc, diag::warn_call_wrong_number_of_arguments)
+            << (NumArgs > Def->param_size()) << FDecl << Fn->getSourceRange();
+        }
+      }
+    }
+
+    // Promote the arguments (C99 6.5.2.2p6).
+    for (unsigned i = 0; i != NumArgs; i++) {
+      Expr *Arg = Args[i];
+      DefaultArgumentPromotion(Arg);
+      if (RequireCompleteType(Arg->getSourceRange().getBegin(),
+                              Arg->getType(),
+                              diag::err_call_incomplete_argument,
+                              Arg->getSourceRange()))
+        return ExprError();
+      TheCall->setArg(i, Arg);
+    }
+  }
+
+  if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(FDecl))
+    if (!Method->isStatic())
+      return ExprError(Diag(LParenLoc, diag::err_member_call_without_object)
+        << Fn->getSourceRange());
+
+  // Check for sentinels
+  if (NDecl)
+    DiagnoseSentinelCalls(NDecl, LParenLoc, Args, NumArgs);
+  // Do special checking on direct calls to functions.
+  if (FDecl)
+    return CheckFunctionCall(FDecl, TheCall.take());
+  if (NDecl)
+    return CheckBlockCall(NDecl, TheCall.take());
+
+  return Owned(TheCall.take());
+}
+
+Action::OwningExprResult
+Sema::ActOnCompoundLiteral(SourceLocation LParenLoc, TypeTy *Ty,
+                           SourceLocation RParenLoc, ExprArg InitExpr) {
+  assert((Ty != 0) && "ActOnCompoundLiteral(): missing type");
+  QualType literalType = QualType::getFromOpaquePtr(Ty);
+  // FIXME: put back this assert when initializers are worked out.
+  //assert((InitExpr != 0) && "ActOnCompoundLiteral(): missing expression");
+  Expr *literalExpr = static_cast<Expr*>(InitExpr.get());
+
+  if (literalType->isArrayType()) {
+    if (literalType->isVariableArrayType())
+      return ExprError(Diag(LParenLoc, diag::err_variable_object_no_init)
+        << SourceRange(LParenLoc, literalExpr->getSourceRange().getEnd()));
+  } else if (!literalType->isDependentType() &&
+             RequireCompleteType(LParenLoc, literalType,
+                                 diag::err_typecheck_decl_incomplete_type,
+                SourceRange(LParenLoc, literalExpr->getSourceRange().getEnd())))
+    return ExprError();
+
+  if (CheckInitializerTypes(literalExpr, literalType, LParenLoc,
+                            DeclarationName(), /*FIXME:DirectInit=*/false))
+    return ExprError();
+
+  bool isFileScope = getCurFunctionOrMethodDecl() == 0;
+  if (isFileScope) { // 6.5.2.5p3
+    if (CheckForConstantInitializer(literalExpr, literalType))
+      return ExprError();
+  }
+  InitExpr.release();
+  return Owned(new (Context) CompoundLiteralExpr(LParenLoc, literalType,
+                                                 literalExpr, isFileScope));
+}
+
+Action::OwningExprResult
+Sema::ActOnInitList(SourceLocation LBraceLoc, MultiExprArg initlist,
+                    SourceLocation RBraceLoc) {
+  unsigned NumInit = initlist.size();
+  Expr **InitList = reinterpret_cast<Expr**>(initlist.release());
+
+  // Semantic analysis for initializers is done by ActOnDeclarator() and
+  // CheckInitializer() - it requires knowledge of the object being intialized.
+
+  InitListExpr *E = new (Context) InitListExpr(LBraceLoc, InitList, NumInit,
+                                               RBraceLoc);
+  E->setType(Context.VoidTy); // FIXME: just a place holder for now.
+  return Owned(E);
+}
+
+/// CheckCastTypes - Check type constraints for casting between types.
+bool Sema::CheckCastTypes(SourceRange TyR, QualType castType, Expr *&castExpr) {
+  UsualUnaryConversions(castExpr);
+
+  // C99 6.5.4p2: the cast type needs to be void or scalar and the expression
+  // type needs to be scalar.
+  if (castType->isVoidType()) {
+    // Cast to void allows any expr type.
+  } else if (castType->isDependentType() || castExpr->isTypeDependent()) {
+    // We can't check any more until template instantiation time.
+  } else if (!castType->isScalarType() && !castType->isVectorType()) {
+    if (Context.getCanonicalType(castType).getUnqualifiedType() ==
+        Context.getCanonicalType(castExpr->getType().getUnqualifiedType()) &&
+        (castType->isStructureType() || castType->isUnionType())) {
+      // GCC struct/union extension: allow cast to self.
+      // FIXME: Check that the cast destination type is complete.
+      Diag(TyR.getBegin(), diag::ext_typecheck_cast_nonscalar)
+        << castType << castExpr->getSourceRange();
+    } else if (castType->isUnionType()) {
+      // GCC cast to union extension
+      RecordDecl *RD = castType->getAsRecordType()->getDecl();
+      RecordDecl::field_iterator Field, FieldEnd;
+      for (Field = RD->field_begin(Context), FieldEnd = RD->field_end(Context);
+           Field != FieldEnd; ++Field) {
+        if (Context.getCanonicalType(Field->getType()).getUnqualifiedType() ==
+            Context.getCanonicalType(castExpr->getType()).getUnqualifiedType()) {
+          Diag(TyR.getBegin(), diag::ext_typecheck_cast_to_union)
+            << castExpr->getSourceRange();
+          break;
+        }
+      }
+      if (Field == FieldEnd)
+        return Diag(TyR.getBegin(), diag::err_typecheck_cast_to_union_no_type)
+          << castExpr->getType() << castExpr->getSourceRange();
+    } else {
+      // Reject any other conversions to non-scalar types.
+      return Diag(TyR.getBegin(), diag::err_typecheck_cond_expect_scalar)
+        << castType << castExpr->getSourceRange();
+    }
+  } else if (!castExpr->getType()->isScalarType() &&
+             !castExpr->getType()->isVectorType()) {
+    return Diag(castExpr->getLocStart(),
+                diag::err_typecheck_expect_scalar_operand)
+      << castExpr->getType() << castExpr->getSourceRange();
+  } else if (castExpr->getType()->isVectorType()) {
+    if (CheckVectorCast(TyR, castExpr->getType(), castType))
+      return true;
+  } else if (castType->isVectorType()) {
+    if (CheckVectorCast(TyR, castType, castExpr->getType()))
+      return true;
+  } else if (getLangOptions().ObjC1 && isa<ObjCSuperExpr>(castExpr)) {
+    return Diag(castExpr->getLocStart(), diag::err_illegal_super_cast) << TyR;
+  } else if (!castType->isArithmeticType()) {
+    QualType castExprType = castExpr->getType();
+    if (!castExprType->isIntegralType() && castExprType->isArithmeticType())
+      return Diag(castExpr->getLocStart(),
+                  diag::err_cast_pointer_from_non_pointer_int)
+        << castExprType << castExpr->getSourceRange();
+  } else if (!castExpr->getType()->isArithmeticType()) {
+    if (!castType->isIntegralType() && castType->isArithmeticType())
+      return Diag(castExpr->getLocStart(),
+                  diag::err_cast_pointer_to_non_pointer_int)
+        << castType << castExpr->getSourceRange();
+  }
+  if (isa<ObjCSelectorExpr>(castExpr))
+    return Diag(castExpr->getLocStart(), diag::err_cast_selector_expr);
+  return false;
+}
+
+bool Sema::CheckVectorCast(SourceRange R, QualType VectorTy, QualType Ty) {
+  assert(VectorTy->isVectorType() && "Not a vector type!");
+
+  if (Ty->isVectorType() || Ty->isIntegerType()) {
+    if (Context.getTypeSize(VectorTy) != Context.getTypeSize(Ty))
+      return Diag(R.getBegin(),
+                  Ty->isVectorType() ?
+                  diag::err_invalid_conversion_between_vectors :
+                  diag::err_invalid_conversion_between_vector_and_integer)
+        << VectorTy << Ty << R;
+  } else
+    return Diag(R.getBegin(),
+                diag::err_invalid_conversion_between_vector_and_scalar)
+      << VectorTy << Ty << R;
+
+  return false;
+}
+
+Action::OwningExprResult
+Sema::ActOnCastExpr(SourceLocation LParenLoc, TypeTy *Ty,
+                    SourceLocation RParenLoc, ExprArg Op) {
+  assert((Ty != 0) && (Op.get() != 0) &&
+         "ActOnCastExpr(): missing type or expr");
+
+  Expr *castExpr = Op.takeAs<Expr>();
+  QualType castType = QualType::getFromOpaquePtr(Ty);
+
+  if (CheckCastTypes(SourceRange(LParenLoc, RParenLoc), castType, castExpr))
+    return ExprError();
+  return Owned(new (Context) CStyleCastExpr(castType, castExpr, castType,
+                                            LParenLoc, RParenLoc));
+}
+
+/// Note that lhs is not null here, even if this is the gnu "x ?: y" extension.
+/// In that case, lhs = cond.
+/// C99 6.5.15
+QualType Sema::CheckConditionalOperands(Expr *&Cond, Expr *&LHS, Expr *&RHS,
+                                        SourceLocation QuestionLoc) {
+  // C++ is sufficiently different to merit its own checker.
+  if (getLangOptions().CPlusPlus)
+    return CXXCheckConditionalOperands(Cond, LHS, RHS, QuestionLoc);
+
+  UsualUnaryConversions(Cond);
+  UsualUnaryConversions(LHS);
+  UsualUnaryConversions(RHS);
+  QualType CondTy = Cond->getType();
+  QualType LHSTy = LHS->getType();
+  QualType RHSTy = RHS->getType();
+
+  // first, check the condition.
+  if (!CondTy->isScalarType()) { // C99 6.5.15p2
+    Diag(Cond->getLocStart(), diag::err_typecheck_cond_expect_scalar)
+      << CondTy;
+    return QualType();
+  }
+
+  // Now check the two expressions.
+
+  // If both operands have arithmetic type, do the usual arithmetic conversions
+  // to find a common type: C99 6.5.15p3,5.
+  if (LHSTy->isArithmeticType() && RHSTy->isArithmeticType()) {
+    UsualArithmeticConversions(LHS, RHS);
+    return LHS->getType();
+  }
+
+  // If both operands are the same structure or union type, the result is that
+  // type.
+  if (const RecordType *LHSRT = LHSTy->getAsRecordType()) {    // C99 6.5.15p3
+    if (const RecordType *RHSRT = RHSTy->getAsRecordType())
+      if (LHSRT->getDecl() == RHSRT->getDecl())
+        // "If both the operands have structure or union type, the result has
+        // that type."  This implies that CV qualifiers are dropped.
+        return LHSTy.getUnqualifiedType();
+    // FIXME: Type of conditional expression must be complete in C mode.
+  }
+
+  // C99 6.5.15p5: "If both operands have void type, the result has void type."
+  // The following || allows only one side to be void (a GCC-ism).
+  if (LHSTy->isVoidType() || RHSTy->isVoidType()) {
+    if (!LHSTy->isVoidType())
+      Diag(RHS->getLocStart(), diag::ext_typecheck_cond_one_void)
+        << RHS->getSourceRange();
+    if (!RHSTy->isVoidType())
+      Diag(LHS->getLocStart(), diag::ext_typecheck_cond_one_void)
+        << LHS->getSourceRange();
+    ImpCastExprToType(LHS, Context.VoidTy);
+    ImpCastExprToType(RHS, Context.VoidTy);
+    return Context.VoidTy;
+  }
+  // C99 6.5.15p6 - "if one operand is a null pointer constant, the result has
+  // the type of the other operand."
+  if ((LHSTy->isPointerType() || LHSTy->isBlockPointerType() ||
+       Context.isObjCObjectPointerType(LHSTy)) &&
+      RHS->isNullPointerConstant(Context)) {
+    ImpCastExprToType(RHS, LHSTy); // promote the null to a pointer.
+    return LHSTy;
+  }
+  if ((RHSTy->isPointerType() || RHSTy->isBlockPointerType() ||
+       Context.isObjCObjectPointerType(RHSTy)) &&
+      LHS->isNullPointerConstant(Context)) {
+    ImpCastExprToType(LHS, RHSTy); // promote the null to a pointer.
+    return RHSTy;
+  }
+
+  const PointerType *LHSPT = LHSTy->getAsPointerType();
+  const PointerType *RHSPT = RHSTy->getAsPointerType();
+  const BlockPointerType *LHSBPT = LHSTy->getAsBlockPointerType();
+  const BlockPointerType *RHSBPT = RHSTy->getAsBlockPointerType();
+
+  // Handle the case where both operands are pointers before we handle null
+  // pointer constants in case both operands are null pointer constants.
+  if ((LHSPT || LHSBPT) && (RHSPT || RHSBPT)) { // C99 6.5.15p3,6
+    // get the "pointed to" types
+    QualType lhptee = (LHSPT ? LHSPT->getPointeeType()
+                       : LHSBPT->getPointeeType());
+      QualType rhptee = (RHSPT ? RHSPT->getPointeeType()
+                         : RHSBPT->getPointeeType());
+
+    // ignore qualifiers on void (C99 6.5.15p3, clause 6)
+    if (lhptee->isVoidType()
+        && (RHSBPT || rhptee->isIncompleteOrObjectType())) {
+      // Figure out necessary qualifiers (C99 6.5.15p6)
+      QualType destPointee=lhptee.getQualifiedType(rhptee.getCVRQualifiers());
+      QualType destType = Context.getPointerType(destPointee);
+      ImpCastExprToType(LHS, destType); // add qualifiers if necessary
+      ImpCastExprToType(RHS, destType); // promote to void*
+      return destType;
+    }
+    if (rhptee->isVoidType()
+        && (LHSBPT || lhptee->isIncompleteOrObjectType())) {
+      QualType destPointee=rhptee.getQualifiedType(lhptee.getCVRQualifiers());
+      QualType destType = Context.getPointerType(destPointee);
+      ImpCastExprToType(LHS, destType); // add qualifiers if necessary
+      ImpCastExprToType(RHS, destType); // promote to void*
+      return destType;
+    }
+
+    bool sameKind = (LHSPT && RHSPT) || (LHSBPT && RHSBPT);
+    if (sameKind
+        && Context.getCanonicalType(LHSTy) == Context.getCanonicalType(RHSTy)) {
+      // Two identical pointer types are always compatible.
+      return LHSTy;
+    }
+
+    QualType compositeType = LHSTy;
+
+    // If either type is an Objective-C object type then check
+    // compatibility according to Objective-C.
+    if (Context.isObjCObjectPointerType(LHSTy) ||
+        Context.isObjCObjectPointerType(RHSTy)) {
+      // If both operands are interfaces and either operand can be
+      // assigned to the other, use that type as the composite
+      // type. This allows
+      //   xxx ? (A*) a : (B*) b
+      // where B is a subclass of A.
+      //
+      // Additionally, as for assignment, if either type is 'id'
+      // allow silent coercion. Finally, if the types are
+      // incompatible then make sure to use 'id' as the composite
+      // type so the result is acceptable for sending messages to.
+
+      // FIXME: Consider unifying with 'areComparableObjCPointerTypes'.
+      // It could return the composite type.
+      const ObjCInterfaceType* LHSIface = lhptee->getAsObjCInterfaceType();
+      const ObjCInterfaceType* RHSIface = rhptee->getAsObjCInterfaceType();
+      if (LHSIface && RHSIface &&
+          Context.canAssignObjCInterfaces(LHSIface, RHSIface)) {
+        compositeType = LHSTy;
+      } else if (LHSIface && RHSIface &&
+                 Context.canAssignObjCInterfaces(RHSIface, LHSIface)) {
+        compositeType = RHSTy;
+      } else if (Context.isObjCIdStructType(lhptee) ||
+                 Context.isObjCIdStructType(rhptee)) {
+        compositeType = Context.getObjCIdType();
+      } else if (LHSBPT || RHSBPT) {
+        if (!sameKind
+            || !Context.typesAreBlockCompatible(lhptee.getUnqualifiedType(),
+                                                rhptee.getUnqualifiedType()))
+          Diag(QuestionLoc, diag::err_typecheck_cond_incompatible_operands)
+            << LHSTy << RHSTy << LHS->getSourceRange() << RHS->getSourceRange();
+        return QualType();
+      } else {
+        Diag(QuestionLoc, diag::ext_typecheck_cond_incompatible_operands)
+          << LHSTy << RHSTy
+          << LHS->getSourceRange() << RHS->getSourceRange();
+        QualType incompatTy = Context.getObjCIdType();
+        ImpCastExprToType(LHS, incompatTy);
+        ImpCastExprToType(RHS, incompatTy);
+        return incompatTy;
+      }
+    } else if (!sameKind
+               || !Context.typesAreCompatible(lhptee.getUnqualifiedType(),
+                                              rhptee.getUnqualifiedType())) {
+      Diag(QuestionLoc, diag::warn_typecheck_cond_incompatible_pointers)
+        << LHSTy << RHSTy << LHS->getSourceRange() << RHS->getSourceRange();
+      // In this situation, we assume void* type. No especially good
+      // reason, but this is what gcc does, and we do have to pick
+      // to get a consistent AST.
+      QualType incompatTy = Context.getPointerType(Context.VoidTy);
+      ImpCastExprToType(LHS, incompatTy);
+      ImpCastExprToType(RHS, incompatTy);
+      return incompatTy;
+    }
+    // The pointer types are compatible.
+    // C99 6.5.15p6: If both operands are pointers to compatible types *or* to
+    // differently qualified versions of compatible types, the result type is
+    // a pointer to an appropriately qualified version of the *composite*
+    // type.
+    // FIXME: Need to calculate the composite type.
+    // FIXME: Need to add qualifiers
+    ImpCastExprToType(LHS, compositeType);
+    ImpCastExprToType(RHS, compositeType);
+    return compositeType;
+  }
+
+  // GCC compatibility: soften pointer/integer mismatch.
+  if (RHSTy->isPointerType() && LHSTy->isIntegerType()) {
+    Diag(QuestionLoc, diag::warn_typecheck_cond_pointer_integer_mismatch)
+      << LHSTy << RHSTy << LHS->getSourceRange() << RHS->getSourceRange();
+    ImpCastExprToType(LHS, RHSTy); // promote the integer to a pointer.
+    return RHSTy;
+  }
+  if (LHSTy->isPointerType() && RHSTy->isIntegerType()) {
+    Diag(QuestionLoc, diag::warn_typecheck_cond_pointer_integer_mismatch)
+      << LHSTy << RHSTy << LHS->getSourceRange() << RHS->getSourceRange();
+    ImpCastExprToType(RHS, LHSTy); // promote the integer to a pointer.
+    return LHSTy;
+  }
+
+  // Need to handle "id<xx>" explicitly. Unlike "id", whose canonical type
+  // evaluates to "struct objc_object *" (and is handled above when comparing
+  // id with statically typed objects).
+  if (LHSTy->isObjCQualifiedIdType() || RHSTy->isObjCQualifiedIdType()) {
+    // GCC allows qualified id and any Objective-C type to devolve to
+    // id. Currently localizing to here until clear this should be
+    // part of ObjCQualifiedIdTypesAreCompatible.
+    if (ObjCQualifiedIdTypesAreCompatible(LHSTy, RHSTy, true) ||
+        (LHSTy->isObjCQualifiedIdType() &&
+         Context.isObjCObjectPointerType(RHSTy)) ||
+        (RHSTy->isObjCQualifiedIdType() &&
+         Context.isObjCObjectPointerType(LHSTy))) {
+      // FIXME: This is not the correct composite type. This only happens to
+      // work because id can more or less be used anywhere, however this may
+      // change the type of method sends.
+
+      // FIXME: gcc adds some type-checking of the arguments and emits
+      // (confusing) incompatible comparison warnings in some
+      // cases. Investigate.
+      QualType compositeType = Context.getObjCIdType();
+      ImpCastExprToType(LHS, compositeType);
+      ImpCastExprToType(RHS, compositeType);
+      return compositeType;
+    }
+  }
+
+  // Otherwise, the operands are not compatible.
+  Diag(QuestionLoc, diag::err_typecheck_cond_incompatible_operands)
+    << LHSTy << RHSTy << LHS->getSourceRange() << RHS->getSourceRange();
+  return QualType();
+}
+
+/// ActOnConditionalOp - Parse a ?: operation.  Note that 'LHS' may be null
+/// in the case of a the GNU conditional expr extension.
+Action::OwningExprResult Sema::ActOnConditionalOp(SourceLocation QuestionLoc,
+                                                  SourceLocation ColonLoc,
+                                                  ExprArg Cond, ExprArg LHS,
+                                                  ExprArg RHS) {
+  Expr *CondExpr = (Expr *) Cond.get();
+  Expr *LHSExpr = (Expr *) LHS.get(), *RHSExpr = (Expr *) RHS.get();
+
+  // If this is the gnu "x ?: y" extension, analyze the types as though the LHS
+  // was the condition.
+  bool isLHSNull = LHSExpr == 0;
+  if (isLHSNull)
+    LHSExpr = CondExpr;
+
+  QualType result = CheckConditionalOperands(CondExpr, LHSExpr,
+                                             RHSExpr, QuestionLoc);
+  if (result.isNull())
+    return ExprError();
+
+  Cond.release();
+  LHS.release();
+  RHS.release();
+  return Owned(new (Context) ConditionalOperator(CondExpr,
+                                                 isLHSNull ? 0 : LHSExpr,
+                                                 RHSExpr, result));
+}
+
+
+// CheckPointerTypesForAssignment - This is a very tricky routine (despite
+// being closely modeled after the C99 spec:-). The odd characteristic of this
+// routine is it effectively iqnores the qualifiers on the top level pointee.
+// This circumvents the usual type rules specified in 6.2.7p1 & 6.7.5.[1-3].
+// FIXME: add a couple examples in this comment.
+Sema::AssignConvertType
+Sema::CheckPointerTypesForAssignment(QualType lhsType, QualType rhsType) {
+  QualType lhptee, rhptee;
+
+  // get the "pointed to" type (ignoring qualifiers at the top level)
+  lhptee = lhsType->getAsPointerType()->getPointeeType();
+  rhptee = rhsType->getAsPointerType()->getPointeeType();
+
+  // make sure we operate on the canonical type
+  lhptee = Context.getCanonicalType(lhptee);
+  rhptee = Context.getCanonicalType(rhptee);
+
+  AssignConvertType ConvTy = Compatible;
+
+  // C99 6.5.16.1p1: This following citation is common to constraints
+  // 3 & 4 (below). ...and the type *pointed to* by the left has all the
+  // qualifiers of the type *pointed to* by the right;
+  // FIXME: Handle ExtQualType
+  if (!lhptee.isAtLeastAsQualifiedAs(rhptee))
+    ConvTy = CompatiblePointerDiscardsQualifiers;
+
+  // C99 6.5.16.1p1 (constraint 4): If one operand is a pointer to an object or
+  // incomplete type and the other is a pointer to a qualified or unqualified
+  // version of void...
+  if (lhptee->isVoidType()) {
+    if (rhptee->isIncompleteOrObjectType())
+      return ConvTy;
+
+    // As an extension, we allow cast to/from void* to function pointer.
+    assert(rhptee->isFunctionType());
+    return FunctionVoidPointer;
+  }
+
+  if (rhptee->isVoidType()) {
+    if (lhptee->isIncompleteOrObjectType())
+      return ConvTy;
+
+    // As an extension, we allow cast to/from void* to function pointer.
+    assert(lhptee->isFunctionType());
+    return FunctionVoidPointer;
+  }
+  // C99 6.5.16.1p1 (constraint 3): both operands are pointers to qualified or
+  // unqualified versions of compatible types, ...
+  lhptee = lhptee.getUnqualifiedType();
+  rhptee = rhptee.getUnqualifiedType();
+  if (!Context.typesAreCompatible(lhptee, rhptee)) {
+    // Check if the pointee types are compatible ignoring the sign.
+    // We explicitly check for char so that we catch "char" vs
+    // "unsigned char" on systems where "char" is unsigned.
+    if (lhptee->isCharType()) {
+      lhptee = Context.UnsignedCharTy;
+    } else if (lhptee->isSignedIntegerType()) {
+      lhptee = Context.getCorrespondingUnsignedType(lhptee);
+    }
+    if (rhptee->isCharType()) {
+      rhptee = Context.UnsignedCharTy;
+    } else if (rhptee->isSignedIntegerType()) {
+      rhptee = Context.getCorrespondingUnsignedType(rhptee);
+    }
+    if (lhptee == rhptee) {
+      // Types are compatible ignoring the sign. Qualifier incompatibility
+      // takes priority over sign incompatibility because the sign
+      // warning can be disabled.
+      if (ConvTy != Compatible)
+        return ConvTy;
+      return IncompatiblePointerSign;
+    }
+    // General pointer incompatibility takes priority over qualifiers.
+    return IncompatiblePointer; 
+  }
+  return ConvTy;
+}
+
+/// CheckBlockPointerTypesForAssignment - This routine determines whether two
+/// block pointer types are compatible or whether a block and normal pointer
+/// are compatible. It is more restrict than comparing two function pointer
+// types.
+Sema::AssignConvertType
+Sema::CheckBlockPointerTypesForAssignment(QualType lhsType,
+                                          QualType rhsType) {
+  QualType lhptee, rhptee;
+
+  // get the "pointed to" type (ignoring qualifiers at the top level)
+  lhptee = lhsType->getAsBlockPointerType()->getPointeeType();
+  rhptee = rhsType->getAsBlockPointerType()->getPointeeType();
+
+  // make sure we operate on the canonical type
+  lhptee = Context.getCanonicalType(lhptee);
+  rhptee = Context.getCanonicalType(rhptee);
+
+  AssignConvertType ConvTy = Compatible;
+
+  // For blocks we enforce that qualifiers are identical.
+  if (lhptee.getCVRQualifiers() != rhptee.getCVRQualifiers())
+    ConvTy = CompatiblePointerDiscardsQualifiers;
+
+  if (!Context.typesAreBlockCompatible(lhptee, rhptee))
+    return IncompatibleBlockPointer;
+  return ConvTy;
+}
+
+/// CheckAssignmentConstraints (C99 6.5.16) - This routine currently
+/// has code to accommodate several GCC extensions when type checking
+/// pointers. Here are some objectionable examples that GCC considers warnings:
+///
+///  int a, *pint;
+///  short *pshort;
+///  struct foo *pfoo;
+///
+///  pint = pshort; // warning: assignment from incompatible pointer type
+///  a = pint; // warning: assignment makes integer from pointer without a cast
+///  pint = a; // warning: assignment makes pointer from integer without a cast
+///  pint = pfoo; // warning: assignment from incompatible pointer type
+///
+/// As a result, the code for dealing with pointers is more complex than the
+/// C99 spec dictates.
+///
+Sema::AssignConvertType
+Sema::CheckAssignmentConstraints(QualType lhsType, QualType rhsType) {
+  // Get canonical types.  We're not formatting these types, just comparing
+  // them.
+  lhsType = Context.getCanonicalType(lhsType).getUnqualifiedType();
+  rhsType = Context.getCanonicalType(rhsType).getUnqualifiedType();
+
+  if (lhsType == rhsType)
+    return Compatible; // Common case: fast path an exact match.
+
+  // If the left-hand side is a reference type, then we are in a
+  // (rare!) case where we've allowed the use of references in C,
+  // e.g., as a parameter type in a built-in function. In this case,
+  // just make sure that the type referenced is compatible with the
+  // right-hand side type. The caller is responsible for adjusting
+  // lhsType so that the resulting expression does not have reference
+  // type.
+  if (const ReferenceType *lhsTypeRef = lhsType->getAsReferenceType()) {
+    if (Context.typesAreCompatible(lhsTypeRef->getPointeeType(), rhsType))
+      return Compatible;
+    return Incompatible;
+  }
+
+  if (lhsType->isObjCQualifiedIdType() || rhsType->isObjCQualifiedIdType()) {
+    if (ObjCQualifiedIdTypesAreCompatible(lhsType, rhsType, false))
+      return Compatible;
+    // Relax integer conversions like we do for pointers below.
+    if (rhsType->isIntegerType())
+      return IntToPointer;
+    if (lhsType->isIntegerType())
+      return PointerToInt;
+    return IncompatibleObjCQualifiedId;
+  }
+
+  if (lhsType->isVectorType() || rhsType->isVectorType()) {
+    // For ExtVector, allow vector splats; float -> <n x float>
+    if (const ExtVectorType *LV = lhsType->getAsExtVectorType())
+      if (LV->getElementType() == rhsType)
+        return Compatible;
+
+    // If we are allowing lax vector conversions, and LHS and RHS are both
+    // vectors, the total size only needs to be the same. This is a bitcast;
+    // no bits are changed but the result type is different.
+    if (getLangOptions().LaxVectorConversions &&
+        lhsType->isVectorType() && rhsType->isVectorType()) {
+      if (Context.getTypeSize(lhsType) == Context.getTypeSize(rhsType))
+        return IncompatibleVectors;
+    }
+    return Incompatible;
+  }
+
+  if (lhsType->isArithmeticType() && rhsType->isArithmeticType())
+    return Compatible;
+
+  if (isa<PointerType>(lhsType)) {
+    if (rhsType->isIntegerType())
+      return IntToPointer;
+
+    if (isa<PointerType>(rhsType))
+      return CheckPointerTypesForAssignment(lhsType, rhsType);
+
+    if (rhsType->getAsBlockPointerType()) {
+      if (lhsType->getAsPointerType()->getPointeeType()->isVoidType())
+        return Compatible;
+
+      // Treat block pointers as objects.
+      if (getLangOptions().ObjC1 &&
+          lhsType == Context.getCanonicalType(Context.getObjCIdType()))
+        return Compatible;
+    }
+    return Incompatible;
+  }
+
+  if (isa<BlockPointerType>(lhsType)) {
+    if (rhsType->isIntegerType())
+      return IntToBlockPointer;
+
+    // Treat block pointers as objects.
+    if (getLangOptions().ObjC1 &&
+        rhsType == Context.getCanonicalType(Context.getObjCIdType()))
+      return Compatible;
+
+    if (rhsType->isBlockPointerType())
+      return CheckBlockPointerTypesForAssignment(lhsType, rhsType);
+
+    if (const PointerType *RHSPT = rhsType->getAsPointerType()) {
+      if (RHSPT->getPointeeType()->isVoidType())
+        return Compatible;
+    }
+    return Incompatible;
+  }
+
+  if (isa<PointerType>(rhsType)) {
+    // C99 6.5.16.1p1: the left operand is _Bool and the right is a pointer.
+    if (lhsType == Context.BoolTy)
+      return Compatible;
+
+    if (lhsType->isIntegerType())
+      return PointerToInt;
+
+    if (isa<PointerType>(lhsType))
+      return CheckPointerTypesForAssignment(lhsType, rhsType);
+
+    if (isa<BlockPointerType>(lhsType) &&
+        rhsType->getAsPointerType()->getPointeeType()->isVoidType())
+      return Compatible;
+    return Incompatible;
+  }
+
+  if (isa<TagType>(lhsType) && isa<TagType>(rhsType)) {
+    if (Context.typesAreCompatible(lhsType, rhsType))
+      return Compatible;
+  }
+  return Incompatible;
+}
+
+/// \brief Constructs a transparent union from an expression that is
+/// used to initialize the transparent union.
+static void ConstructTransparentUnion(ASTContext &C, Expr *&E, 
+                                      QualType UnionType, FieldDecl *Field) {
+  // Build an initializer list that designates the appropriate member
+  // of the transparent union.
+  InitListExpr *Initializer = new (C) InitListExpr(SourceLocation(),
+                                                   &E, 1,
+                                                   SourceLocation());
+  Initializer->setType(UnionType);
+  Initializer->setInitializedFieldInUnion(Field);
+
+  // Build a compound literal constructing a value of the transparent
+  // union type from this initializer list.
+  E = new (C) CompoundLiteralExpr(SourceLocation(), UnionType, Initializer,
+                                  false);
+}
+
+Sema::AssignConvertType
+Sema::CheckTransparentUnionArgumentConstraints(QualType ArgType, Expr *&rExpr) {
+  QualType FromType = rExpr->getType();
+
+  // If the ArgType is a Union type, we want to handle a potential 
+  // transparent_union GCC extension.
+  const RecordType *UT = ArgType->getAsUnionType();
+  if (!UT || !UT->getDecl()->hasAttr<TransparentUnionAttr>())
+    return Incompatible;
+
+  // The field to initialize within the transparent union.
+  RecordDecl *UD = UT->getDecl();
+  FieldDecl *InitField = 0;
+  // It's compatible if the expression matches any of the fields.
+  for (RecordDecl::field_iterator it = UD->field_begin(Context),
+         itend = UD->field_end(Context);
+       it != itend; ++it) {
+    if (it->getType()->isPointerType()) {
+      // If the transparent union contains a pointer type, we allow:
+      // 1) void pointer
+      // 2) null pointer constant
+      if (FromType->isPointerType())
+        if (FromType->getAsPointerType()->getPointeeType()->isVoidType()) {
+          ImpCastExprToType(rExpr, it->getType());
+          InitField = *it;
+          break;
+        }
+      
+      if (rExpr->isNullPointerConstant(Context)) {
+        ImpCastExprToType(rExpr, it->getType());
+        InitField = *it;
+        break;
+      }
+    }
+
+    if (CheckAssignmentConstraints(it->getType(), rExpr->getType())
+          == Compatible) {
+      InitField = *it;
+      break;
+    }
+  }
+
+  if (!InitField)
+    return Incompatible;
+
+  ConstructTransparentUnion(Context, rExpr, ArgType, InitField);
+  return Compatible;
+}
+
+Sema::AssignConvertType
+Sema::CheckSingleAssignmentConstraints(QualType lhsType, Expr *&rExpr) {
+  if (getLangOptions().CPlusPlus) {
+    if (!lhsType->isRecordType()) {
+      // C++ 5.17p3: If the left operand is not of class type, the
+      // expression is implicitly converted (C++ 4) to the
+      // cv-unqualified type of the left operand.
+      if (PerformImplicitConversion(rExpr, lhsType.getUnqualifiedType(),
+                                    "assigning"))
+        return Incompatible;
+      return Compatible;
+    }
+
+    // FIXME: Currently, we fall through and treat C++ classes like C
+    // structures.
+  }
+
+  // C99 6.5.16.1p1: the left operand is a pointer and the right is
+  // a null pointer constant.
+  if ((lhsType->isPointerType() || 
+       lhsType->isObjCQualifiedIdType() || 
+       lhsType->isBlockPointerType())
+      && rExpr->isNullPointerConstant(Context)) {
+    ImpCastExprToType(rExpr, lhsType);
+    return Compatible;
+  }
+
+  // This check seems unnatural, however it is necessary to ensure the proper
+  // conversion of functions/arrays. If the conversion were done for all
+  // DeclExpr's (created by ActOnIdentifierExpr), it would mess up the unary
+  // expressions that surpress this implicit conversion (&, sizeof).
+  //
+  // Suppress this for references: C++ 8.5.3p5.
+  if (!lhsType->isReferenceType())
+    DefaultFunctionArrayConversion(rExpr);
+
+  Sema::AssignConvertType result =
+    CheckAssignmentConstraints(lhsType, rExpr->getType());
+
+  // C99 6.5.16.1p2: The value of the right operand is converted to the
+  // type of the assignment expression.
+  // CheckAssignmentConstraints allows the left-hand side to be a reference,
+  // so that we can use references in built-in functions even in C.
+  // The getNonReferenceType() call makes sure that the resulting expression
+  // does not have reference type.
+  if (result != Incompatible && rExpr->getType() != lhsType)
+    ImpCastExprToType(rExpr, lhsType.getNonReferenceType());
+  return result;
+}
+
+QualType Sema::InvalidOperands(SourceLocation Loc, Expr *&lex, Expr *&rex) {
+  Diag(Loc, diag::err_typecheck_invalid_operands)
+    << lex->getType() << rex->getType()
+    << lex->getSourceRange() << rex->getSourceRange();
+  return QualType();
+}
+
+inline QualType Sema::CheckVectorOperands(SourceLocation Loc, Expr *&lex,
+                                                              Expr *&rex) {
+  // For conversion purposes, we ignore any qualifiers.
+  // For example, "const float" and "float" are equivalent.
+  QualType lhsType =
+    Context.getCanonicalType(lex->getType()).getUnqualifiedType();
+  QualType rhsType =
+    Context.getCanonicalType(rex->getType()).getUnqualifiedType();
+
+  // If the vector types are identical, return.
+  if (lhsType == rhsType)
+    return lhsType;
+
+  // Handle the case of a vector & extvector type of the same size and element
+  // type.  It would be nice if we only had one vector type someday.
+  if (getLangOptions().LaxVectorConversions) {
+    // FIXME: Should we warn here?
+    if (const VectorType *LV = lhsType->getAsVectorType()) {
+      if (const VectorType *RV = rhsType->getAsVectorType())
+        if (LV->getElementType() == RV->getElementType() &&
+            LV->getNumElements() == RV->getNumElements()) {
+          return lhsType->isExtVectorType() ? lhsType : rhsType;
+        }
+    }
+  }
+
+  // If the lhs is an extended vector and the rhs is a scalar of the same type
+  // or a literal, promote the rhs to the vector type.
+  if (const ExtVectorType *V = lhsType->getAsExtVectorType()) {
+    QualType eltType = V->getElementType();
+
+    if ((eltType->getAsBuiltinType() == rhsType->getAsBuiltinType()) ||
+        (eltType->isIntegerType() && isa<IntegerLiteral>(rex)) ||
+        (eltType->isFloatingType() && isa<FloatingLiteral>(rex))) {
+      ImpCastExprToType(rex, lhsType);
+      return lhsType;
+    }
+  }
+
+  // If the rhs is an extended vector and the lhs is a scalar of the same type,
+  // promote the lhs to the vector type.
+  if (const ExtVectorType *V = rhsType->getAsExtVectorType()) {
+    QualType eltType = V->getElementType();
+
+    if ((eltType->getAsBuiltinType() == lhsType->getAsBuiltinType()) ||
+        (eltType->isIntegerType() && isa<IntegerLiteral>(lex)) ||
+        (eltType->isFloatingType() && isa<FloatingLiteral>(lex))) {
+      ImpCastExprToType(lex, rhsType);
+      return rhsType;
+    }
+  }
+
+  // You cannot convert between vector values of different size.
+  Diag(Loc, diag::err_typecheck_vector_not_convertable)
+    << lex->getType() << rex->getType()
+    << lex->getSourceRange() << rex->getSourceRange();
+  return QualType();
+}
+
+inline QualType Sema::CheckMultiplyDivideOperands(
+  Expr *&lex, Expr *&rex, SourceLocation Loc, bool isCompAssign)
+{
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType())
+    return CheckVectorOperands(Loc, lex, rex);
+
+  QualType compType = UsualArithmeticConversions(lex, rex, isCompAssign);
+
+  if (lex->getType()->isArithmeticType() && rex->getType()->isArithmeticType())
+    return compType;
+  return InvalidOperands(Loc, lex, rex);
+}
+
+inline QualType Sema::CheckRemainderOperands(
+  Expr *&lex, Expr *&rex, SourceLocation Loc, bool isCompAssign)
+{
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType()) {
+    if (lex->getType()->isIntegerType() && rex->getType()->isIntegerType())
+      return CheckVectorOperands(Loc, lex, rex);
+    return InvalidOperands(Loc, lex, rex);
+  }
+
+  QualType compType = UsualArithmeticConversions(lex, rex, isCompAssign);
+
+  if (lex->getType()->isIntegerType() && rex->getType()->isIntegerType())
+    return compType;
+  return InvalidOperands(Loc, lex, rex);
+}
+
+inline QualType Sema::CheckAdditionOperands( // C99 6.5.6
+  Expr *&lex, Expr *&rex, SourceLocation Loc, QualType* CompLHSTy)
+{
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType()) {
+    QualType compType = CheckVectorOperands(Loc, lex, rex);
+    if (CompLHSTy) *CompLHSTy = compType;
+    return compType;
+  }
+
+  QualType compType = UsualArithmeticConversions(lex, rex, CompLHSTy);
+
+  // handle the common case first (both operands are arithmetic).
+  if (lex->getType()->isArithmeticType() &&
+      rex->getType()->isArithmeticType()) {
+    if (CompLHSTy) *CompLHSTy = compType;
+    return compType;
+  }
+
+  // Put any potential pointer into PExp
+  Expr* PExp = lex, *IExp = rex;
+  if (IExp->getType()->isPointerType())
+    std::swap(PExp, IExp);
+
+  if (const PointerType *PTy = PExp->getType()->getAsPointerType()) {
+    if (IExp->getType()->isIntegerType()) {
+      QualType PointeeTy = PTy->getPointeeType();
+      // Check for arithmetic on pointers to incomplete types.
+      if (PointeeTy->isVoidType()) {
+        if (getLangOptions().CPlusPlus) {
+          Diag(Loc, diag::err_typecheck_pointer_arith_void_type)
+            << lex->getSourceRange() << rex->getSourceRange();
+          return QualType();
+        }
+
+        // GNU extension: arithmetic on pointer to void
+        Diag(Loc, diag::ext_gnu_void_ptr)
+          << lex->getSourceRange() << rex->getSourceRange();
+      } else if (PointeeTy->isFunctionType()) {
+        if (getLangOptions().CPlusPlus) {
+          Diag(Loc, diag::err_typecheck_pointer_arith_function_type)
+            << lex->getType() << lex->getSourceRange();
+          return QualType();
+        }
+
+        // GNU extension: arithmetic on pointer to function
+        Diag(Loc, diag::ext_gnu_ptr_func_arith)
+          << lex->getType() << lex->getSourceRange();
+      } else if (!PTy->isDependentType() &&
+                 RequireCompleteType(Loc, PointeeTy,
+                                diag::err_typecheck_arithmetic_incomplete_type,
+                                     PExp->getSourceRange(), SourceRange(),
+                                     PExp->getType()))
+        return QualType();
+
+      // Diagnose bad cases where we step over interface counts.
+      if (PointeeTy->isObjCInterfaceType() && LangOpts.ObjCNonFragileABI) {
+        Diag(Loc, diag::err_arithmetic_nonfragile_interface)
+          << PointeeTy << PExp->getSourceRange();
+        return QualType();
+      }
+      
+      if (CompLHSTy) {
+        QualType LHSTy = lex->getType();
+        if (LHSTy->isPromotableIntegerType())
+          LHSTy = Context.IntTy;
+        else {
+          QualType T = isPromotableBitField(lex, Context);
+          if (!T.isNull())
+            LHSTy = T;
+        }
+
+        *CompLHSTy = LHSTy;
+      }
+      return PExp->getType();
+    }
+  }
+
+  return InvalidOperands(Loc, lex, rex);
+}
+
+// C99 6.5.6
+QualType Sema::CheckSubtractionOperands(Expr *&lex, Expr *&rex,
+                                        SourceLocation Loc, QualType* CompLHSTy) {
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType()) {
+    QualType compType = CheckVectorOperands(Loc, lex, rex);
+    if (CompLHSTy) *CompLHSTy = compType;
+    return compType;
+  }
+
+  QualType compType = UsualArithmeticConversions(lex, rex, CompLHSTy);
+
+  // Enforce type constraints: C99 6.5.6p3.
+
+  // Handle the common case first (both operands are arithmetic).
+  if (lex->getType()->isArithmeticType()
+      && rex->getType()->isArithmeticType()) {
+    if (CompLHSTy) *CompLHSTy = compType;
+    return compType;
+  }
+
+  // Either ptr - int   or   ptr - ptr.
+  if (const PointerType *LHSPTy = lex->getType()->getAsPointerType()) {
+    QualType lpointee = LHSPTy->getPointeeType();
+
+    // The LHS must be an completely-defined object type.
+
+    bool ComplainAboutVoid = false;
+    Expr *ComplainAboutFunc = 0;
+    if (lpointee->isVoidType()) {
+      if (getLangOptions().CPlusPlus) {
+        Diag(Loc, diag::err_typecheck_pointer_arith_void_type)
+          << lex->getSourceRange() << rex->getSourceRange();
+        return QualType();
+      }
+
+      // GNU C extension: arithmetic on pointer to void
+      ComplainAboutVoid = true;
+    } else if (lpointee->isFunctionType()) {
+      if (getLangOptions().CPlusPlus) {
+        Diag(Loc, diag::err_typecheck_pointer_arith_function_type)
+          << lex->getType() << lex->getSourceRange();
+        return QualType();
+      }
+
+      // GNU C extension: arithmetic on pointer to function
+      ComplainAboutFunc = lex;
+    } else if (!lpointee->isDependentType() &&
+               RequireCompleteType(Loc, lpointee, 
+                                   diag::err_typecheck_sub_ptr_object,
+                                   lex->getSourceRange(),
+                                   SourceRange(),
+                                   lex->getType()))
+      return QualType();
+
+    // Diagnose bad cases where we step over interface counts.
+    if (lpointee->isObjCInterfaceType() && LangOpts.ObjCNonFragileABI) {
+      Diag(Loc, diag::err_arithmetic_nonfragile_interface)
+        << lpointee << lex->getSourceRange();
+      return QualType();
+    }
+    
+    // The result type of a pointer-int computation is the pointer type.
+    if (rex->getType()->isIntegerType()) {
+      if (ComplainAboutVoid)
+        Diag(Loc, diag::ext_gnu_void_ptr)
+          << lex->getSourceRange() << rex->getSourceRange();
+      if (ComplainAboutFunc)
+        Diag(Loc, diag::ext_gnu_ptr_func_arith)
+          << ComplainAboutFunc->getType() 
+          << ComplainAboutFunc->getSourceRange();
+
+      if (CompLHSTy) *CompLHSTy = lex->getType();
+      return lex->getType();
+    }
+
+    // Handle pointer-pointer subtractions.
+    if (const PointerType *RHSPTy = rex->getType()->getAsPointerType()) {
+      QualType rpointee = RHSPTy->getPointeeType();
+
+      // RHS must be a completely-type object type.
+      // Handle the GNU void* extension.
+      if (rpointee->isVoidType()) {
+        if (getLangOptions().CPlusPlus) {
+          Diag(Loc, diag::err_typecheck_pointer_arith_void_type)
+            << lex->getSourceRange() << rex->getSourceRange();
+          return QualType();
+        }
+
+        ComplainAboutVoid = true;
+      } else if (rpointee->isFunctionType()) {
+        if (getLangOptions().CPlusPlus) {
+          Diag(Loc, diag::err_typecheck_pointer_arith_function_type)
+            << rex->getType() << rex->getSourceRange();
+          return QualType();
+        }
+
+        // GNU extension: arithmetic on pointer to function
+        if (!ComplainAboutFunc)
+          ComplainAboutFunc = rex;
+      } else if (!rpointee->isDependentType() &&
+                 RequireCompleteType(Loc, rpointee,
+                                     diag::err_typecheck_sub_ptr_object,
+                                     rex->getSourceRange(),
+                                     SourceRange(),
+                                     rex->getType()))
+        return QualType();
+
+      if (getLangOptions().CPlusPlus) {
+        // Pointee types must be the same: C++ [expr.add]
+        if (!Context.hasSameUnqualifiedType(lpointee, rpointee)) {
+          Diag(Loc, diag::err_typecheck_sub_ptr_compatible)
+            << lex->getType() << rex->getType()
+            << lex->getSourceRange() << rex->getSourceRange();
+          return QualType();
+        }
+      } else {
+        // Pointee types must be compatible C99 6.5.6p3
+        if (!Context.typesAreCompatible(
+                Context.getCanonicalType(lpointee).getUnqualifiedType(),
+                Context.getCanonicalType(rpointee).getUnqualifiedType())) {
+          Diag(Loc, diag::err_typecheck_sub_ptr_compatible)
+            << lex->getType() << rex->getType()
+            << lex->getSourceRange() << rex->getSourceRange();
+          return QualType();
+        }
+      }
+
+      if (ComplainAboutVoid)
+        Diag(Loc, diag::ext_gnu_void_ptr)
+          << lex->getSourceRange() << rex->getSourceRange();
+      if (ComplainAboutFunc)
+        Diag(Loc, diag::ext_gnu_ptr_func_arith)
+          << ComplainAboutFunc->getType() 
+          << ComplainAboutFunc->getSourceRange();
+
+      if (CompLHSTy) *CompLHSTy = lex->getType();
+      return Context.getPointerDiffType();
+    }
+  }
+
+  return InvalidOperands(Loc, lex, rex);
+}
+
+// C99 6.5.7
+QualType Sema::CheckShiftOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
+                                  bool isCompAssign) {
+  // C99 6.5.7p2: Each of the operands shall have integer type.
+  if (!lex->getType()->isIntegerType() || !rex->getType()->isIntegerType())
+    return InvalidOperands(Loc, lex, rex);
+
+  // Shifts don't perform usual arithmetic conversions, they just do integer
+  // promotions on each operand. C99 6.5.7p3
+  QualType LHSTy;
+  if (lex->getType()->isPromotableIntegerType())
+    LHSTy = Context.IntTy;
+  else {
+    LHSTy = isPromotableBitField(lex, Context);
+    if (LHSTy.isNull())
+      LHSTy = lex->getType();
+  }
+  if (!isCompAssign)
+    ImpCastExprToType(lex, LHSTy);
+
+  UsualUnaryConversions(rex);
+
+  // "The type of the result is that of the promoted left operand."
+  return LHSTy;
+}
+
+// C99 6.5.8, C++ [expr.rel]
+QualType Sema::CheckCompareOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
+                                    unsigned OpaqueOpc, bool isRelational) {
+  BinaryOperator::Opcode Opc = (BinaryOperator::Opcode)OpaqueOpc;
+
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType())
+    return CheckVectorCompareOperands(lex, rex, Loc, isRelational);
+
+  // C99 6.5.8p3 / C99 6.5.9p4
+  if (lex->getType()->isArithmeticType() && rex->getType()->isArithmeticType())
+    UsualArithmeticConversions(lex, rex);
+  else {
+    UsualUnaryConversions(lex);
+    UsualUnaryConversions(rex);
+  }
+  QualType lType = lex->getType();
+  QualType rType = rex->getType();
+
+  if (!lType->isFloatingType()
+      && !(lType->isBlockPointerType() && isRelational)) {
+    // For non-floating point types, check for self-comparisons of the form
+    // x == x, x != x, x < x, etc.  These always evaluate to a constant, and
+    // often indicate logic errors in the program.
+    // NOTE: Don't warn about comparisons of enum constants. These can arise 
+    //  from macro expansions, and are usually quite deliberate.
+    Expr *LHSStripped = lex->IgnoreParens();
+    Expr *RHSStripped = rex->IgnoreParens();
+    if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LHSStripped))
+      if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RHSStripped))
+        if (DRL->getDecl() == DRR->getDecl() &&
+            !isa<EnumConstantDecl>(DRL->getDecl()))
+          Diag(Loc, diag::warn_selfcomparison);
+    
+    if (isa<CastExpr>(LHSStripped))
+      LHSStripped = LHSStripped->IgnoreParenCasts();
+    if (isa<CastExpr>(RHSStripped))
+      RHSStripped = RHSStripped->IgnoreParenCasts();
+    
+    // Warn about comparisons against a string constant (unless the other
+    // operand is null), the user probably wants strcmp.
+    Expr *literalString = 0;
+    Expr *literalStringStripped = 0;
+    if ((isa<StringLiteral>(LHSStripped) || isa<ObjCEncodeExpr>(LHSStripped)) &&
+        !RHSStripped->isNullPointerConstant(Context)) {
+      literalString = lex;
+      literalStringStripped = LHSStripped;
+    }
+    else if ((isa<StringLiteral>(RHSStripped) ||
+              isa<ObjCEncodeExpr>(RHSStripped)) &&
+             !LHSStripped->isNullPointerConstant(Context)) {
+      literalString = rex;
+      literalStringStripped = RHSStripped;
+    }
+
+    if (literalString) {
+      std::string resultComparison;
+      switch (Opc) {
+      case BinaryOperator::LT: resultComparison = ") < 0"; break;
+      case BinaryOperator::GT: resultComparison = ") > 0"; break;
+      case BinaryOperator::LE: resultComparison = ") <= 0"; break;
+      case BinaryOperator::GE: resultComparison = ") >= 0"; break;
+      case BinaryOperator::EQ: resultComparison = ") == 0"; break;
+      case BinaryOperator::NE: resultComparison = ") != 0"; break;
+      default: assert(false && "Invalid comparison operator");
+      }
+      Diag(Loc, diag::warn_stringcompare)
+        << isa<ObjCEncodeExpr>(literalStringStripped)
+        << literalString->getSourceRange()
+        << CodeModificationHint::CreateReplacement(SourceRange(Loc), ", ")
+        << CodeModificationHint::CreateInsertion(lex->getLocStart(),
+                                                 "strcmp(")
+        << CodeModificationHint::CreateInsertion(
+                                       PP.getLocForEndOfToken(rex->getLocEnd()),
+                                       resultComparison);
+    }
+  }
+
+  // The result of comparisons is 'bool' in C++, 'int' in C.
+  QualType ResultTy = getLangOptions().CPlusPlus? Context.BoolTy :Context.IntTy;
+
+  if (isRelational) {
+    if (lType->isRealType() && rType->isRealType())
+      return ResultTy;
+  } else {
+    // Check for comparisons of floating point operands using != and ==.
+    if (lType->isFloatingType()) {
+      assert(rType->isFloatingType());
+      CheckFloatComparison(Loc,lex,rex);
+    }
+
+    if (lType->isArithmeticType() && rType->isArithmeticType())
+      return ResultTy;
+  }
+
+  bool LHSIsNull = lex->isNullPointerConstant(Context);
+  bool RHSIsNull = rex->isNullPointerConstant(Context);
+
+  // All of the following pointer related warnings are GCC extensions, except
+  // when handling null pointer constants. One day, we can consider making them
+  // errors (when -pedantic-errors is enabled).
+  if (lType->isPointerType() && rType->isPointerType()) { // C99 6.5.8p2
+    QualType LCanPointeeTy =
+      Context.getCanonicalType(lType->getAsPointerType()->getPointeeType());
+    QualType RCanPointeeTy =
+      Context.getCanonicalType(rType->getAsPointerType()->getPointeeType());
+
+    // Simple check: if the pointee types are identical, we're done.
+    if (LCanPointeeTy == RCanPointeeTy)
+      return ResultTy;
+
+    if (getLangOptions().CPlusPlus) {
+      // C++ [expr.rel]p2:
+      //   [...] Pointer conversions (4.10) and qualification
+      //   conversions (4.4) are performed on pointer operands (or on
+      //   a pointer operand and a null pointer constant) to bring
+      //   them to their composite pointer type. [...]
+      //
+      // C++ [expr.eq]p2 uses the same notion for (in)equality
+      // comparisons of pointers.
+      QualType T = FindCompositePointerType(lex, rex);
+      if (T.isNull()) {
+        Diag(Loc, diag::err_typecheck_comparison_of_distinct_pointers)
+          << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+        return QualType();
+      }
+
+      ImpCastExprToType(lex, T);
+      ImpCastExprToType(rex, T);
+      return ResultTy;
+    }
+
+    if (!LHSIsNull && !RHSIsNull &&                       // C99 6.5.9p2
+        !LCanPointeeTy->isVoidType() && !RCanPointeeTy->isVoidType() &&
+        !Context.typesAreCompatible(LCanPointeeTy.getUnqualifiedType(),
+                                    RCanPointeeTy.getUnqualifiedType()) &&
+        !Context.areComparableObjCPointerTypes(lType, rType)) {
+      Diag(Loc, diag::ext_typecheck_comparison_of_distinct_pointers)
+        << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+    }
+    ImpCastExprToType(rex, lType); // promote the pointer to pointer
+    return ResultTy;
+  }
+  // C++ allows comparison of pointers with null pointer constants.
+  if (getLangOptions().CPlusPlus) {
+    if (lType->isPointerType() && RHSIsNull) {
+      ImpCastExprToType(rex, lType);
+      return ResultTy;
+    }
+    if (rType->isPointerType() && LHSIsNull) {
+      ImpCastExprToType(lex, rType);
+      return ResultTy;
+    }
+    // And comparison of nullptr_t with itself.
+    if (lType->isNullPtrType() && rType->isNullPtrType())
+      return ResultTy;
+  }
+  // Handle block pointer types.
+  if (!isRelational && lType->isBlockPointerType() && rType->isBlockPointerType()) {
+    QualType lpointee = lType->getAsBlockPointerType()->getPointeeType();
+    QualType rpointee = rType->getAsBlockPointerType()->getPointeeType();
+
+    if (!LHSIsNull && !RHSIsNull &&
+        !Context.typesAreBlockCompatible(lpointee, rpointee)) {
+      Diag(Loc, diag::err_typecheck_comparison_of_distinct_blocks)
+        << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+    }
+    ImpCastExprToType(rex, lType); // promote the pointer to pointer
+    return ResultTy;
+  }
+  // Allow block pointers to be compared with null pointer constants.
+  if (!isRelational
+      && ((lType->isBlockPointerType() && rType->isPointerType())
+          || (lType->isPointerType() && rType->isBlockPointerType()))) {
+    if (!LHSIsNull && !RHSIsNull) {
+      if (!((rType->isPointerType() && rType->getAsPointerType()
+             ->getPointeeType()->isVoidType())
+            || (lType->isPointerType() && lType->getAsPointerType()
+                ->getPointeeType()->isVoidType())))
+        Diag(Loc, diag::err_typecheck_comparison_of_distinct_blocks)
+          << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+    }
+    ImpCastExprToType(rex, lType); // promote the pointer to pointer
+    return ResultTy;
+  }
+
+  if ((lType->isObjCQualifiedIdType() || rType->isObjCQualifiedIdType())) {
+    if (lType->isPointerType() || rType->isPointerType()) {
+      const PointerType *LPT = lType->getAsPointerType();
+      const PointerType *RPT = rType->getAsPointerType();
+      bool LPtrToVoid = LPT ?
+        Context.getCanonicalType(LPT->getPointeeType())->isVoidType() : false;
+      bool RPtrToVoid = RPT ?
+        Context.getCanonicalType(RPT->getPointeeType())->isVoidType() : false;
+
+      if (!LPtrToVoid && !RPtrToVoid &&
+          !Context.typesAreCompatible(lType, rType)) {
+        Diag(Loc, diag::ext_typecheck_comparison_of_distinct_pointers)
+          << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+        ImpCastExprToType(rex, lType);
+        return ResultTy;
+      }
+      ImpCastExprToType(rex, lType);
+      return ResultTy;
+    }
+    if (ObjCQualifiedIdTypesAreCompatible(lType, rType, true)) {
+      ImpCastExprToType(rex, lType);
+      return ResultTy;
+    } else {
+      if ((lType->isObjCQualifiedIdType() && rType->isObjCQualifiedIdType())) {
+        Diag(Loc, diag::warn_incompatible_qualified_id_operands)
+          << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+        ImpCastExprToType(rex, lType);
+        return ResultTy;
+      }
+    }
+  }
+  if ((lType->isPointerType() || lType->isObjCQualifiedIdType()) &&
+       rType->isIntegerType()) {
+    if (!RHSIsNull)
+      Diag(Loc, diag::ext_typecheck_comparison_of_pointer_integer)
+        << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+    ImpCastExprToType(rex, lType); // promote the integer to pointer
+    return ResultTy;
+  }
+  if (lType->isIntegerType() &&
+      (rType->isPointerType() || rType->isObjCQualifiedIdType())) {
+    if (!LHSIsNull)
+      Diag(Loc, diag::ext_typecheck_comparison_of_pointer_integer)
+        << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+    ImpCastExprToType(lex, rType); // promote the integer to pointer
+    return ResultTy;
+  }
+  // Handle block pointers.
+  if (!isRelational && RHSIsNull
+      && lType->isBlockPointerType() && rType->isIntegerType()) {
+    ImpCastExprToType(rex, lType); // promote the integer to pointer
+    return ResultTy;
+  }
+  if (!isRelational && LHSIsNull
+      && lType->isIntegerType() && rType->isBlockPointerType()) {
+    ImpCastExprToType(lex, rType); // promote the integer to pointer
+    return ResultTy;
+  }
+  return InvalidOperands(Loc, lex, rex);
+}
+
+/// CheckVectorCompareOperands - vector comparisons are a clang extension that
+/// operates on extended vector types.  Instead of producing an IntTy result,
+/// like a scalar comparison, a vector comparison produces a vector of integer
+/// types.
+QualType Sema::CheckVectorCompareOperands(Expr *&lex, Expr *&rex,
+                                          SourceLocation Loc,
+                                          bool isRelational) {
+  // Check to make sure we're operating on vectors of the same type and width,
+  // Allowing one side to be a scalar of element type.
+  QualType vType = CheckVectorOperands(Loc, lex, rex);
+  if (vType.isNull())
+    return vType;
+
+  QualType lType = lex->getType();
+  QualType rType = rex->getType();
+
+  // For non-floating point types, check for self-comparisons of the form
+  // x == x, x != x, x < x, etc.  These always evaluate to a constant, and
+  // often indicate logic errors in the program.
+  if (!lType->isFloatingType()) {
+    if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(lex->IgnoreParens()))
+      if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(rex->IgnoreParens()))
+        if (DRL->getDecl() == DRR->getDecl())
+          Diag(Loc, diag::warn_selfcomparison);
+  }
+
+  // Check for comparisons of floating point operands using != and ==.
+  if (!isRelational && lType->isFloatingType()) {
+    assert (rType->isFloatingType());
+    CheckFloatComparison(Loc,lex,rex);
+  }
+
+  // FIXME: Vector compare support in the LLVM backend is not fully reliable,
+  // just reject all vector comparisons for now.
+  if (1) {
+    Diag(Loc, diag::err_typecheck_vector_comparison)
+      << lType << rType << lex->getSourceRange() << rex->getSourceRange();
+    return QualType();
+  }
+
+  // Return the type for the comparison, which is the same as vector type for
+  // integer vectors, or an integer type of identical size and number of
+  // elements for floating point vectors.
+  if (lType->isIntegerType())
+    return lType;
+
+  const VectorType *VTy = lType->getAsVectorType();
+  unsigned TypeSize = Context.getTypeSize(VTy->getElementType());
+  if (TypeSize == Context.getTypeSize(Context.IntTy))
+    return Context.getExtVectorType(Context.IntTy, VTy->getNumElements());
+  if (TypeSize == Context.getTypeSize(Context.LongTy))
+    return Context.getExtVectorType(Context.LongTy, VTy->getNumElements());
+
+  assert(TypeSize == Context.getTypeSize(Context.LongLongTy) &&
+         "Unhandled vector element size in vector compare");
+  return Context.getExtVectorType(Context.LongLongTy, VTy->getNumElements());
+}
+
+inline QualType Sema::CheckBitwiseOperands(
+  Expr *&lex, Expr *&rex, SourceLocation Loc, bool isCompAssign)
+{
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType())
+    return CheckVectorOperands(Loc, lex, rex);
+
+  QualType compType = UsualArithmeticConversions(lex, rex, isCompAssign);
+
+  if (lex->getType()->isIntegerType() && rex->getType()->isIntegerType())
+    return compType;
+  return InvalidOperands(Loc, lex, rex);
+}
+
+inline QualType Sema::CheckLogicalOperands( // C99 6.5.[13,14]
+  Expr *&lex, Expr *&rex, SourceLocation Loc)
+{
+  UsualUnaryConversions(lex);
+  UsualUnaryConversions(rex);
+
+  if (lex->getType()->isScalarType() && rex->getType()->isScalarType())
+    return Context.IntTy;
+  return InvalidOperands(Loc, lex, rex);
+}
+
+/// IsReadonlyProperty - Verify that otherwise a valid l-value expression
+/// is a read-only property; return true if so. A readonly property expression
+/// depends on various declarations and thus must be treated specially.
+///
+static bool IsReadonlyProperty(Expr *E, Sema &S)
+{
+  if (E->getStmtClass() == Expr::ObjCPropertyRefExprClass) {
+    const ObjCPropertyRefExpr* PropExpr = cast<ObjCPropertyRefExpr>(E);
+    if (ObjCPropertyDecl *PDecl = PropExpr->getProperty()) {
+      QualType BaseType = PropExpr->getBase()->getType();
+      if (const PointerType *PTy = BaseType->getAsPointerType())
+        if (const ObjCInterfaceType *IFTy =
+            PTy->getPointeeType()->getAsObjCInterfaceType())
+          if (ObjCInterfaceDecl *IFace = IFTy->getDecl())
+            if (S.isPropertyReadonly(PDecl, IFace))
+              return true;
+    }
+  }
+  return false;
+}
+
+/// CheckForModifiableLvalue - Verify that E is a modifiable lvalue.  If not,
+/// emit an error and return true.  If so, return false.
+static bool CheckForModifiableLvalue(Expr *E, SourceLocation Loc, Sema &S) {
+  SourceLocation OrigLoc = Loc;
+  Expr::isModifiableLvalueResult IsLV = E->isModifiableLvalue(S.Context, 
+                                                              &Loc);
+  if (IsLV == Expr::MLV_Valid && IsReadonlyProperty(E, S))
+    IsLV = Expr::MLV_ReadonlyProperty;
+  if (IsLV == Expr::MLV_Valid)
+    return false;
+
+  unsigned Diag = 0;
+  bool NeedType = false;
+  switch (IsLV) { // C99 6.5.16p2
+  default: assert(0 && "Unknown result from isModifiableLvalue!");
+  case Expr::MLV_ConstQualified: Diag = diag::err_typecheck_assign_const; break;
+  case Expr::MLV_ArrayType:
+    Diag = diag::err_typecheck_array_not_modifiable_lvalue;
+    NeedType = true;
+    break;
+  case Expr::MLV_NotObjectType:
+    Diag = diag::err_typecheck_non_object_not_modifiable_lvalue;
+    NeedType = true;
+    break;
+  case Expr::MLV_LValueCast:
+    Diag = diag::err_typecheck_lvalue_casts_not_supported;
+    break;
+  case Expr::MLV_InvalidExpression:
+    Diag = diag::err_typecheck_expression_not_modifiable_lvalue;
+    break;
+  case Expr::MLV_IncompleteType:
+  case Expr::MLV_IncompleteVoidType:
+    return S.RequireCompleteType(Loc, E->getType(),
+                      diag::err_typecheck_incomplete_type_not_modifiable_lvalue,
+                                    E->getSourceRange());
+  case Expr::MLV_DuplicateVectorComponents:
+    Diag = diag::err_typecheck_duplicate_vector_components_not_mlvalue;
+    break;
+  case Expr::MLV_NotBlockQualified:
+    Diag = diag::err_block_decl_ref_not_modifiable_lvalue;
+    break;
+  case Expr::MLV_ReadonlyProperty:
+    Diag = diag::error_readonly_property_assignment;
+    break;
+  case Expr::MLV_NoSetterProperty:
+    Diag = diag::error_nosetter_property_assignment;
+    break;
+  }
+
+  SourceRange Assign;
+  if (Loc != OrigLoc)
+    Assign = SourceRange(OrigLoc, OrigLoc);
+  if (NeedType)
+    S.Diag(Loc, Diag) << E->getType() << E->getSourceRange() << Assign;
+  else
+    S.Diag(Loc, Diag) << E->getSourceRange() << Assign; 
+  return true;
+}
+
+
+
+// C99 6.5.16.1
+QualType Sema::CheckAssignmentOperands(Expr *LHS, Expr *&RHS,
+                                       SourceLocation Loc,
+                                       QualType CompoundType) {
+  // Verify that LHS is a modifiable lvalue, and emit error if not.
+  if (CheckForModifiableLvalue(LHS, Loc, *this))
+    return QualType();
+
+  QualType LHSType = LHS->getType();
+  QualType RHSType = CompoundType.isNull() ? RHS->getType() : CompoundType;
+
+  AssignConvertType ConvTy;
+  if (CompoundType.isNull()) {
+    // Simple assignment "x = y".
+    ConvTy = CheckSingleAssignmentConstraints(LHSType, RHS);
+    // Special case of NSObject attributes on c-style pointer types.
+    if (ConvTy == IncompatiblePointer &&
+        ((Context.isObjCNSObjectType(LHSType) &&
+          Context.isObjCObjectPointerType(RHSType)) ||
+         (Context.isObjCNSObjectType(RHSType) &&
+          Context.isObjCObjectPointerType(LHSType))))
+      ConvTy = Compatible;
+
+    // If the RHS is a unary plus or minus, check to see if they = and + are
+    // right next to each other.  If so, the user may have typo'd "x =+ 4"
+    // instead of "x += 4".
+    Expr *RHSCheck = RHS;
+    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(RHSCheck))
+      RHSCheck = ICE->getSubExpr();
+    if (UnaryOperator *UO = dyn_cast<UnaryOperator>(RHSCheck)) {
+      if ((UO->getOpcode() == UnaryOperator::Plus ||
+           UO->getOpcode() == UnaryOperator::Minus) &&
+          Loc.isFileID() && UO->getOperatorLoc().isFileID() &&
+          // Only if the two operators are exactly adjacent.
+          Loc.getFileLocWithOffset(1) == UO->getOperatorLoc() &&
+          // And there is a space or other character before the subexpr of the
+          // unary +/-.  We don't want to warn on "x=-1".
+          Loc.getFileLocWithOffset(2) != UO->getSubExpr()->getLocStart() &&
+          UO->getSubExpr()->getLocStart().isFileID()) {
+        Diag(Loc, diag::warn_not_compound_assign)
+          << (UO->getOpcode() == UnaryOperator::Plus ? "+" : "-")
+          << SourceRange(UO->getOperatorLoc(), UO->getOperatorLoc());
+      }
+    }
+  } else {
+    // Compound assignment "x += y"
+    ConvTy = CheckAssignmentConstraints(LHSType, RHSType);
+  }
+
+  if (DiagnoseAssignmentResult(ConvTy, Loc, LHSType, RHSType,
+                               RHS, "assigning"))
+    return QualType();
+
+  // C99 6.5.16p3: The type of an assignment expression is the type of the
+  // left operand unless the left operand has qualified type, in which case
+  // it is the unqualified version of the type of the left operand.
+  // C99 6.5.16.1p2: In simple assignment, the value of the right operand
+  // is converted to the type of the assignment expression (above).
+  // C++ 5.17p1: the type of the assignment expression is that of its left
+  // operand.
+  return LHSType.getUnqualifiedType();
+}
+
+// C99 6.5.17
+QualType Sema::CheckCommaOperands(Expr *LHS, Expr *&RHS, SourceLocation Loc) {
+  // Comma performs lvalue conversion (C99 6.3.2.1), but not unary conversions.
+  DefaultFunctionArrayConversion(RHS);
+
+  // FIXME: Check that RHS type is complete in C mode (it's legal for it to be
+  // incomplete in C++).
+
+  return RHS->getType();
+}
+
+/// CheckIncrementDecrementOperand - unlike most "Check" methods, this routine
+/// doesn't need to call UsualUnaryConversions or UsualArithmeticConversions.
+QualType Sema::CheckIncrementDecrementOperand(Expr *Op, SourceLocation OpLoc,
+                                              bool isInc) {
+  if (Op->isTypeDependent())
+    return Context.DependentTy;
+
+  QualType ResType = Op->getType();
+  assert(!ResType.isNull() && "no type for increment/decrement expression");
+
+  if (getLangOptions().CPlusPlus && ResType->isBooleanType()) {
+    // Decrement of bool is not allowed.
+    if (!isInc) {
+      Diag(OpLoc, diag::err_decrement_bool) << Op->getSourceRange();
+      return QualType();
+    }
+    // Increment of bool sets it to true, but is deprecated.
+    Diag(OpLoc, diag::warn_increment_bool) << Op->getSourceRange();
+  } else if (ResType->isRealType()) {
+    // OK!
+  } else if (const PointerType *PT = ResType->getAsPointerType()) {
+    // C99 6.5.2.4p2, 6.5.6p2
+    if (PT->getPointeeType()->isVoidType()) {
+      if (getLangOptions().CPlusPlus) {
+        Diag(OpLoc, diag::err_typecheck_pointer_arith_void_type)
+          << Op->getSourceRange();
+        return QualType();
+      }
+
+      // Pointer to void is a GNU extension in C.
+      Diag(OpLoc, diag::ext_gnu_void_ptr) << Op->getSourceRange();
+    } else if (PT->getPointeeType()->isFunctionType()) {
+      if (getLangOptions().CPlusPlus) {
+        Diag(OpLoc, diag::err_typecheck_pointer_arith_function_type)
+          << Op->getType() << Op->getSourceRange();
+        return QualType();
+      }
+
+      Diag(OpLoc, diag::ext_gnu_ptr_func_arith)
+        << ResType << Op->getSourceRange();
+    } else if (RequireCompleteType(OpLoc, PT->getPointeeType(),
+                               diag::err_typecheck_arithmetic_incomplete_type,
+                                   Op->getSourceRange(), SourceRange(),
+                                   ResType))
+      return QualType();
+  } else if (ResType->isComplexType()) {
+    // C99 does not support ++/-- on complex types, we allow as an extension.
+    Diag(OpLoc, diag::ext_integer_increment_complex)
+      << ResType << Op->getSourceRange();
+  } else {
+    Diag(OpLoc, diag::err_typecheck_illegal_increment_decrement)
+      << ResType << Op->getSourceRange();
+    return QualType();
+  }
+  // At this point, we know we have a real, complex or pointer type.
+  // Now make sure the operand is a modifiable lvalue.
+  if (CheckForModifiableLvalue(Op, OpLoc, *this))
+    return QualType();
+  return ResType;
+}
+
+/// getPrimaryDecl - Helper function for CheckAddressOfOperand().
+/// This routine allows us to typecheck complex/recursive expressions
+/// where the declaration is needed for type checking. We only need to
+/// handle cases when the expression references a function designator
+/// or is an lvalue. Here are some examples:
+///  - &(x) => x
+///  - &*****f => f for f a function designator.
+///  - &s.xx => s
+///  - &s.zz[1].yy -> s, if zz is an array
+///  - *(x + 1) -> x, if x is an array
+///  - &"123"[2] -> 0
+///  - & __real__ x -> x
+static NamedDecl *getPrimaryDecl(Expr *E) {
+  switch (E->getStmtClass()) {
+  case Stmt::DeclRefExprClass:
+  case Stmt::QualifiedDeclRefExprClass:
+    return cast<DeclRefExpr>(E)->getDecl();
+  case Stmt::MemberExprClass:
+    // If this is an arrow operator, the address is an offset from
+    // the base's value, so the object the base refers to is
+    // irrelevant.
+    if (cast<MemberExpr>(E)->isArrow())
+      return 0;
+    // Otherwise, the expression refers to a part of the base
+    return getPrimaryDecl(cast<MemberExpr>(E)->getBase());
+  case Stmt::ArraySubscriptExprClass: {
+    // FIXME: This code shouldn't be necessary!  We should catch the implicit
+    // promotion of register arrays earlier.
+    Expr* Base = cast<ArraySubscriptExpr>(E)->getBase();
+    if (ImplicitCastExpr* ICE = dyn_cast<ImplicitCastExpr>(Base)) {
+      if (ICE->getSubExpr()->getType()->isArrayType())
+        return getPrimaryDecl(ICE->getSubExpr());
+    }
+    return 0;
+  }
+  case Stmt::UnaryOperatorClass: {
+    UnaryOperator *UO = cast<UnaryOperator>(E);
+
+    switch(UO->getOpcode()) {
+    case UnaryOperator::Real:
+    case UnaryOperator::Imag:
+    case UnaryOperator::Extension:
+      return getPrimaryDecl(UO->getSubExpr());
+    default:
+      return 0;
+    }
+  }
+  case Stmt::ParenExprClass:
+    return getPrimaryDecl(cast<ParenExpr>(E)->getSubExpr());
+  case Stmt::ImplicitCastExprClass:
+    // If the result of an implicit cast is an l-value, we care about
+    // the sub-expression; otherwise, the result here doesn't matter.
+    return getPrimaryDecl(cast<ImplicitCastExpr>(E)->getSubExpr());
+  default:
+    return 0;
+  }
+}
+
+/// CheckAddressOfOperand - The operand of & must be either a function
+/// designator or an lvalue designating an object. If it is an lvalue, the
+/// object cannot be declared with storage class register or be a bit field.
+/// Note: The usual conversions are *not* applied to the operand of the &
+/// operator (C99 6.3.2.1p[2-4]), and its result is never an lvalue.
+/// In C++, the operand might be an overloaded function name, in which case
+/// we allow the '&' but retain the overloaded-function type.
+QualType Sema::CheckAddressOfOperand(Expr *op, SourceLocation OpLoc) {
+  // Make sure to ignore parentheses in subsequent checks
+  op = op->IgnoreParens();
+
+  if (op->isTypeDependent())
+    return Context.DependentTy;
+
+  if (getLangOptions().C99) {
+    // Implement C99-only parts of addressof rules.
+    if (UnaryOperator* uOp = dyn_cast<UnaryOperator>(op)) {
+      if (uOp->getOpcode() == UnaryOperator::Deref)
+        // Per C99 6.5.3.2, the address of a deref always returns a valid result
+        // (assuming the deref expression is valid).
+        return uOp->getSubExpr()->getType();
+    }
+    // Technically, there should be a check for array subscript
+    // expressions here, but the result of one is always an lvalue anyway.
+  }
+  NamedDecl *dcl = getPrimaryDecl(op);
+  Expr::isLvalueResult lval = op->isLvalue(Context);
+
+  if (lval != Expr::LV_Valid && lval != Expr::LV_IncompleteVoidType) {
+    // C99 6.5.3.2p1
+    // The operand must be either an l-value or a function designator
+    if (!op->getType()->isFunctionType()) {
+      // FIXME: emit more specific diag...
+      Diag(OpLoc, diag::err_typecheck_invalid_lvalue_addrof)
+        << op->getSourceRange();
+      return QualType();
+    }
+  } else if (op->getBitField()) { // C99 6.5.3.2p1
+    // The operand cannot be a bit-field
+    Diag(OpLoc, diag::err_typecheck_address_of)
+      << "bit-field" << op->getSourceRange();
+        return QualType();
+  } else if (isa<ExtVectorElementExpr>(op) || (isa<ArraySubscriptExpr>(op) &&
+           cast<ArraySubscriptExpr>(op)->getBase()->getType()->isVectorType())){
+    // The operand cannot be an element of a vector
+    Diag(OpLoc, diag::err_typecheck_address_of)
+      << "vector element" << op->getSourceRange();
+    return QualType();
+  } else if (dcl) { // C99 6.5.3.2p1
+    // We have an lvalue with a decl. Make sure the decl is not declared
+    // with the register storage-class specifier.
+    if (const VarDecl *vd = dyn_cast<VarDecl>(dcl)) {
+      if (vd->getStorageClass() == VarDecl::Register) {
+        Diag(OpLoc, diag::err_typecheck_address_of)
+          << "register variable" << op->getSourceRange();
+        return QualType();
+      }
+    } else if (isa<OverloadedFunctionDecl>(dcl)) {
+      return Context.OverloadTy;
+    } else if (isa<FieldDecl>(dcl)) {
+      // Okay: we can take the address of a field.
+      // Could be a pointer to member, though, if there is an explicit
+      // scope qualifier for the class.
+      if (isa<QualifiedDeclRefExpr>(op)) {
+        DeclContext *Ctx = dcl->getDeclContext();
+        if (Ctx && Ctx->isRecord())
+          return Context.getMemberPointerType(op->getType(),
+                Context.getTypeDeclType(cast<RecordDecl>(Ctx)).getTypePtr());
+      }
+    } else if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(dcl)) {
+      // Okay: we can take the address of a function.
+      // As above.
+      if (isa<QualifiedDeclRefExpr>(op) && MD->isInstance())
+        return Context.getMemberPointerType(op->getType(),
+              Context.getTypeDeclType(MD->getParent()).getTypePtr());
+    } else if (!isa<FunctionDecl>(dcl))
+      assert(0 && "Unknown/unexpected decl type");
+  }
+
+  if (lval == Expr::LV_IncompleteVoidType) {
+    // Taking the address of a void variable is technically illegal, but we
+    // allow it in cases which are otherwise valid.
+    // Example: "extern void x; void* y = &x;".
+    Diag(OpLoc, diag::ext_typecheck_addrof_void) << op->getSourceRange();
+  }
+
+  // If the operand has type "type", the result has type "pointer to type".
+  return Context.getPointerType(op->getType());
+}
+
+QualType Sema::CheckIndirectionOperand(Expr *Op, SourceLocation OpLoc) {
+  if (Op->isTypeDependent())
+    return Context.DependentTy;
+
+  UsualUnaryConversions(Op);
+  QualType Ty = Op->getType();
+
+  // Note that per both C89 and C99, this is always legal, even if ptype is an
+  // incomplete type or void.  It would be possible to warn about dereferencing
+  // a void pointer, but it's completely well-defined, and such a warning is
+  // unlikely to catch any mistakes.
+  if (const PointerType *PT = Ty->getAsPointerType())
+    return PT->getPointeeType();
+
+  Diag(OpLoc, diag::err_typecheck_indirection_requires_pointer)
+    << Ty << Op->getSourceRange();
+  return QualType();
+}
+
+static inline BinaryOperator::Opcode ConvertTokenKindToBinaryOpcode(
+  tok::TokenKind Kind) {
+  BinaryOperator::Opcode Opc;
+  switch (Kind) {
+  default: assert(0 && "Unknown binop!");
+  case tok::periodstar:           Opc = BinaryOperator::PtrMemD; break;
+  case tok::arrowstar:            Opc = BinaryOperator::PtrMemI; break;
+  case tok::star:                 Opc = BinaryOperator::Mul; break;
+  case tok::slash:                Opc = BinaryOperator::Div; break;
+  case tok::percent:              Opc = BinaryOperator::Rem; break;
+  case tok::plus:                 Opc = BinaryOperator::Add; break;
+  case tok::minus:                Opc = BinaryOperator::Sub; break;
+  case tok::lessless:             Opc = BinaryOperator::Shl; break;
+  case tok::greatergreater:       Opc = BinaryOperator::Shr; break;
+  case tok::lessequal:            Opc = BinaryOperator::LE; break;
+  case tok::less:                 Opc = BinaryOperator::LT; break;
+  case tok::greaterequal:         Opc = BinaryOperator::GE; break;
+  case tok::greater:              Opc = BinaryOperator::GT; break;
+  case tok::exclaimequal:         Opc = BinaryOperator::NE; break;
+  case tok::equalequal:           Opc = BinaryOperator::EQ; break;
+  case tok::amp:                  Opc = BinaryOperator::And; break;
+  case tok::caret:                Opc = BinaryOperator::Xor; break;
+  case tok::pipe:                 Opc = BinaryOperator::Or; break;
+  case tok::ampamp:               Opc = BinaryOperator::LAnd; break;
+  case tok::pipepipe:             Opc = BinaryOperator::LOr; break;
+  case tok::equal:                Opc = BinaryOperator::Assign; break;
+  case tok::starequal:            Opc = BinaryOperator::MulAssign; break;
+  case tok::slashequal:           Opc = BinaryOperator::DivAssign; break;
+  case tok::percentequal:         Opc = BinaryOperator::RemAssign; break;
+  case tok::plusequal:            Opc = BinaryOperator::AddAssign; break;
+  case tok::minusequal:           Opc = BinaryOperator::SubAssign; break;
+  case tok::lesslessequal:        Opc = BinaryOperator::ShlAssign; break;
+  case tok::greatergreaterequal:  Opc = BinaryOperator::ShrAssign; break;
+  case tok::ampequal:             Opc = BinaryOperator::AndAssign; break;
+  case tok::caretequal:           Opc = BinaryOperator::XorAssign; break;
+  case tok::pipeequal:            Opc = BinaryOperator::OrAssign; break;
+  case tok::comma:                Opc = BinaryOperator::Comma; break;
+  }
+  return Opc;
+}
+
+static inline UnaryOperator::Opcode ConvertTokenKindToUnaryOpcode(
+  tok::TokenKind Kind) {
+  UnaryOperator::Opcode Opc;
+  switch (Kind) {
+  default: assert(0 && "Unknown unary op!");
+  case tok::plusplus:     Opc = UnaryOperator::PreInc; break;
+  case tok::minusminus:   Opc = UnaryOperator::PreDec; break;
+  case tok::amp:          Opc = UnaryOperator::AddrOf; break;
+  case tok::star:         Opc = UnaryOperator::Deref; break;
+  case tok::plus:         Opc = UnaryOperator::Plus; break;
+  case tok::minus:        Opc = UnaryOperator::Minus; break;
+  case tok::tilde:        Opc = UnaryOperator::Not; break;
+  case tok::exclaim:      Opc = UnaryOperator::LNot; break;
+  case tok::kw___real:    Opc = UnaryOperator::Real; break;
+  case tok::kw___imag:    Opc = UnaryOperator::Imag; break;
+  case tok::kw___extension__: Opc = UnaryOperator::Extension; break;
+  }
+  return Opc;
+}
+
+/// CreateBuiltinBinOp - Creates a new built-in binary operation with
+/// operator @p Opc at location @c TokLoc. This routine only supports
+/// built-in operations; ActOnBinOp handles overloaded operators.
+Action::OwningExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
+                                                  unsigned Op,
+                                                  Expr *lhs, Expr *rhs) {
+  QualType ResultTy;     // Result type of the binary operator.
+  BinaryOperator::Opcode Opc = (BinaryOperator::Opcode)Op;
+  // The following two variables are used for compound assignment operators
+  QualType CompLHSTy;    // Type of LHS after promotions for computation
+  QualType CompResultTy; // Type of computation result
+
+  switch (Opc) {
+  case BinaryOperator::Assign:
+    ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, QualType());
+    break;
+  case BinaryOperator::PtrMemD:
+  case BinaryOperator::PtrMemI:
+    ResultTy = CheckPointerToMemberOperands(lhs, rhs, OpLoc,
+                                            Opc == BinaryOperator::PtrMemI);
+    break;
+  case BinaryOperator::Mul:
+  case BinaryOperator::Div:
+    ResultTy = CheckMultiplyDivideOperands(lhs, rhs, OpLoc);
+    break;
+  case BinaryOperator::Rem:
+    ResultTy = CheckRemainderOperands(lhs, rhs, OpLoc);
+    break;
+  case BinaryOperator::Add:
+    ResultTy = CheckAdditionOperands(lhs, rhs, OpLoc);
+    break;
+  case BinaryOperator::Sub:
+    ResultTy = CheckSubtractionOperands(lhs, rhs, OpLoc);
+    break;
+  case BinaryOperator::Shl:
+  case BinaryOperator::Shr:
+    ResultTy = CheckShiftOperands(lhs, rhs, OpLoc);
+    break;
+  case BinaryOperator::LE:
+  case BinaryOperator::LT:
+  case BinaryOperator::GE:
+  case BinaryOperator::GT:
+    ResultTy = CheckCompareOperands(lhs, rhs, OpLoc, Opc, true);
+    break;
+  case BinaryOperator::EQ:
+  case BinaryOperator::NE:
+    ResultTy = CheckCompareOperands(lhs, rhs, OpLoc, Opc, false);
+    break;
+  case BinaryOperator::And:
+  case BinaryOperator::Xor:
+  case BinaryOperator::Or:
+    ResultTy = CheckBitwiseOperands(lhs, rhs, OpLoc);
+    break;
+  case BinaryOperator::LAnd:
+  case BinaryOperator::LOr:
+    ResultTy = CheckLogicalOperands(lhs, rhs, OpLoc);
+    break;
+  case BinaryOperator::MulAssign:
+  case BinaryOperator::DivAssign:
+    CompResultTy = CheckMultiplyDivideOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
+    break;
+  case BinaryOperator::RemAssign:
+    CompResultTy = CheckRemainderOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
+    break;
+  case BinaryOperator::AddAssign:
+    CompResultTy = CheckAdditionOperands(lhs, rhs, OpLoc, &CompLHSTy);
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
+    break;
+  case BinaryOperator::SubAssign:
+    CompResultTy = CheckSubtractionOperands(lhs, rhs, OpLoc, &CompLHSTy);
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
+    break;
+  case BinaryOperator::ShlAssign:
+  case BinaryOperator::ShrAssign:
+    CompResultTy = CheckShiftOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
+    break;
+  case BinaryOperator::AndAssign:
+  case BinaryOperator::XorAssign:
+  case BinaryOperator::OrAssign:
+    CompResultTy = CheckBitwiseOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
+    break;
+  case BinaryOperator::Comma:
+    ResultTy = CheckCommaOperands(lhs, rhs, OpLoc);
+    break;
+  }
+  if (ResultTy.isNull())
+    return ExprError();
+  if (CompResultTy.isNull())
+    return Owned(new (Context) BinaryOperator(lhs, rhs, Opc, ResultTy, OpLoc));
+  else
+    return Owned(new (Context) CompoundAssignOperator(lhs, rhs, Opc, ResultTy,
+                                                      CompLHSTy, CompResultTy,
+                                                      OpLoc));
+}
+
+// Binary Operators.  'Tok' is the token for the operator.
+Action::OwningExprResult Sema::ActOnBinOp(Scope *S, SourceLocation TokLoc,
+                                          tok::TokenKind Kind,
+                                          ExprArg LHS, ExprArg RHS) {
+  BinaryOperator::Opcode Opc = ConvertTokenKindToBinaryOpcode(Kind);
+  Expr *lhs = LHS.takeAs<Expr>(), *rhs = RHS.takeAs<Expr>();
+
+  assert((lhs != 0) && "ActOnBinOp(): missing left expression");
+  assert((rhs != 0) && "ActOnBinOp(): missing right expression");
+
+  if (getLangOptions().CPlusPlus &&
+      (lhs->getType()->isOverloadableType() || 
+       rhs->getType()->isOverloadableType())) {
+    // Find all of the overloaded operators visible from this
+    // point. We perform both an operator-name lookup from the local
+    // scope and an argument-dependent lookup based on the types of
+    // the arguments.
+    FunctionSet Functions;
+    OverloadedOperatorKind OverOp = BinaryOperator::getOverloadedOperator(Opc);
+    if (OverOp != OO_None) {
+      LookupOverloadedOperatorName(OverOp, S, lhs->getType(), rhs->getType(),
+                                   Functions);
+      Expr *Args[2] = { lhs, rhs };
+      DeclarationName OpName 
+        = Context.DeclarationNames.getCXXOperatorName(OverOp);
+      ArgumentDependentLookup(OpName, Args, 2, Functions);
+    }
+
+    // Build the (potentially-overloaded, potentially-dependent)
+    // binary operation.
+    return CreateOverloadedBinOp(TokLoc, Opc, Functions, lhs, rhs);
+  }
+
+  // Build a built-in binary operation.
+  return CreateBuiltinBinOp(TokLoc, Opc, lhs, rhs);
+}
+
+Action::OwningExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
+                                                    unsigned OpcIn, 
+                                                    ExprArg InputArg) {
+  UnaryOperator::Opcode Opc = static_cast<UnaryOperator::Opcode>(OpcIn);
+
+  // FIXME: Input is modified below, but InputArg is not updated appropriately.
+  Expr *Input = (Expr *)InputArg.get();
+  QualType resultType;
+  switch (Opc) {
+  case UnaryOperator::PostInc:
+  case UnaryOperator::PostDec:
+  case UnaryOperator::OffsetOf:
+    assert(false && "Invalid unary operator");
+    break;
+
+  case UnaryOperator::PreInc:
+  case UnaryOperator::PreDec:
+    resultType = CheckIncrementDecrementOperand(Input, OpLoc,
+                                                Opc == UnaryOperator::PreInc);
+    break;
+  case UnaryOperator::AddrOf:
+    resultType = CheckAddressOfOperand(Input, OpLoc);
+    break;
+  case UnaryOperator::Deref:
+    DefaultFunctionArrayConversion(Input);
+    resultType = CheckIndirectionOperand(Input, OpLoc);
+    break;
+  case UnaryOperator::Plus:
+  case UnaryOperator::Minus:
+    UsualUnaryConversions(Input);
+    resultType = Input->getType();
+    if (resultType->isDependentType())
+      break;
+    if (resultType->isArithmeticType()) // C99 6.5.3.3p1
+      break;
+    else if (getLangOptions().CPlusPlus && // C++ [expr.unary.op]p6-7
+             resultType->isEnumeralType())
+      break;
+    else if (getLangOptions().CPlusPlus && // C++ [expr.unary.op]p6
+             Opc == UnaryOperator::Plus &&
+             resultType->isPointerType())
+      break;
+
+    return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
+      << resultType << Input->getSourceRange());
+  case UnaryOperator::Not: // bitwise complement
+    UsualUnaryConversions(Input);
+    resultType = Input->getType();
+    if (resultType->isDependentType())
+      break;
+    // C99 6.5.3.3p1. We allow complex int and float as a GCC extension.
+    if (resultType->isComplexType() || resultType->isComplexIntegerType())
+      // C99 does not support '~' for complex conjugation.
+      Diag(OpLoc, diag::ext_integer_complement_complex)
+        << resultType << Input->getSourceRange();
+    else if (!resultType->isIntegerType())
+      return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
+        << resultType << Input->getSourceRange());
+    break;
+  case UnaryOperator::LNot: // logical negation
+    // Unlike +/-/~, integer promotions aren't done here (C99 6.5.3.3p5).
+    DefaultFunctionArrayConversion(Input);
+    resultType = Input->getType();
+    if (resultType->isDependentType())
+      break;
+    if (!resultType->isScalarType()) // C99 6.5.3.3p1
+      return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
+        << resultType << Input->getSourceRange());
+    // LNot always has type int. C99 6.5.3.3p5.
+    // In C++, it's bool. C++ 5.3.1p8
+    resultType = getLangOptions().CPlusPlus ? Context.BoolTy : Context.IntTy;
+    break;
+  case UnaryOperator::Real:
+  case UnaryOperator::Imag:
+    resultType = CheckRealImagOperand(Input, OpLoc, Opc == UnaryOperator::Real);
+    break;
+  case UnaryOperator::Extension:
+    resultType = Input->getType();
+    break;
+  }
+  if (resultType.isNull())
+    return ExprError();
+
+  InputArg.release();
+  return Owned(new (Context) UnaryOperator(Input, Opc, resultType, OpLoc));
+}
+
+// Unary Operators.  'Tok' is the token for the operator.
+Action::OwningExprResult Sema::ActOnUnaryOp(Scope *S, SourceLocation OpLoc,
+                                            tok::TokenKind Op, ExprArg input) {
+  Expr *Input = (Expr*)input.get();
+  UnaryOperator::Opcode Opc = ConvertTokenKindToUnaryOpcode(Op);
+
+  if (getLangOptions().CPlusPlus && Input->getType()->isOverloadableType()) {
+    // Find all of the overloaded operators visible from this
+    // point. We perform both an operator-name lookup from the local
+    // scope and an argument-dependent lookup based on the types of
+    // the arguments.
+    FunctionSet Functions;
+    OverloadedOperatorKind OverOp = UnaryOperator::getOverloadedOperator(Opc);
+    if (OverOp != OO_None) {
+      LookupOverloadedOperatorName(OverOp, S, Input->getType(), QualType(),
+                                   Functions);
+      DeclarationName OpName 
+        = Context.DeclarationNames.getCXXOperatorName(OverOp);
+      ArgumentDependentLookup(OpName, &Input, 1, Functions);
+    }
+
+    return CreateOverloadedUnaryOp(OpLoc, Opc, Functions, move(input));
+  }
+
+  return CreateBuiltinUnaryOp(OpLoc, Opc, move(input));
+}
+
+/// ActOnAddrLabel - Parse the GNU address of label extension: "&&foo".
+Sema::OwningExprResult Sema::ActOnAddrLabel(SourceLocation OpLoc,
+                                            SourceLocation LabLoc,
+                                            IdentifierInfo *LabelII) {
+  // Look up the record for this label identifier.
+  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
+
+  // If we haven't seen this label yet, create a forward reference. It
+  // will be validated and/or cleaned up in ActOnFinishFunctionBody.
+  if (LabelDecl == 0)
+    LabelDecl = new (Context) LabelStmt(LabLoc, LabelII, 0);
+
+  // Create the AST node.  The address of a label always has type 'void*'.
+  return Owned(new (Context) AddrLabelExpr(OpLoc, LabLoc, LabelDecl,
+                                       Context.getPointerType(Context.VoidTy)));
+}
+
+Sema::OwningExprResult
+Sema::ActOnStmtExpr(SourceLocation LPLoc, StmtArg substmt,
+                    SourceLocation RPLoc) { // "({..})"
+  Stmt *SubStmt = static_cast<Stmt*>(substmt.get());
+  assert(SubStmt && isa<CompoundStmt>(SubStmt) && "Invalid action invocation!");
+  CompoundStmt *Compound = cast<CompoundStmt>(SubStmt);
+
+  bool isFileScope = getCurFunctionOrMethodDecl() == 0;
+  if (isFileScope)
+    return ExprError(Diag(LPLoc, diag::err_stmtexpr_file_scope));
+
+  // FIXME: there are a variety of strange constraints to enforce here, for
+  // example, it is not possible to goto into a stmt expression apparently.
+  // More semantic analysis is needed.
+
+  // If there are sub stmts in the compound stmt, take the type of the last one
+  // as the type of the stmtexpr.
+  QualType Ty = Context.VoidTy;
+
+  if (!Compound->body_empty()) {
+    Stmt *LastStmt = Compound->body_back();
+    // If LastStmt is a label, skip down through into the body.
+    while (LabelStmt *Label = dyn_cast<LabelStmt>(LastStmt))
+      LastStmt = Label->getSubStmt();
+
+    if (Expr *LastExpr = dyn_cast<Expr>(LastStmt))
+      Ty = LastExpr->getType();
+  }
+
+  // FIXME: Check that expression type is complete/non-abstract; statement
+  // expressions are not lvalues.
+
+  substmt.release();
+  return Owned(new (Context) StmtExpr(Compound, Ty, LPLoc, RPLoc));
+}
+
+Sema::OwningExprResult Sema::ActOnBuiltinOffsetOf(Scope *S,
+                                                  SourceLocation BuiltinLoc,
+                                                  SourceLocation TypeLoc,
+                                                  TypeTy *argty,
+                                                  OffsetOfComponent *CompPtr,
+                                                  unsigned NumComponents,
+                                                  SourceLocation RPLoc) {
+  // FIXME: This function leaks all expressions in the offset components on
+  // error.
+  QualType ArgTy = QualType::getFromOpaquePtr(argty);
+  assert(!ArgTy.isNull() && "Missing type argument!");
+
+  bool Dependent = ArgTy->isDependentType();
+
+  // We must have at least one component that refers to the type, and the first
+  // one is known to be a field designator.  Verify that the ArgTy represents
+  // a struct/union/class.
+  if (!Dependent && !ArgTy->isRecordType())
+    return ExprError(Diag(TypeLoc, diag::err_offsetof_record_type) << ArgTy);
+
+  // FIXME: Type must be complete per C99 7.17p3 because a declaring a variable
+  // with an incomplete type would be illegal.
+
+  // Otherwise, create a null pointer as the base, and iteratively process
+  // the offsetof designators.
+  QualType ArgTyPtr = Context.getPointerType(ArgTy);
+  Expr* Res = new (Context) ImplicitValueInitExpr(ArgTyPtr);
+  Res = new (Context) UnaryOperator(Res, UnaryOperator::Deref,
+                                    ArgTy, SourceLocation());
+
+  // offsetof with non-identifier designators (e.g. "offsetof(x, a.b[c])") are a
+  // GCC extension, diagnose them.
+  // FIXME: This diagnostic isn't actually visible because the location is in
+  // a system header!
+  if (NumComponents != 1)
+    Diag(BuiltinLoc, diag::ext_offsetof_extended_field_designator)
+      << SourceRange(CompPtr[1].LocStart, CompPtr[NumComponents-1].LocEnd);
+
+  if (!Dependent) {
+    bool DidWarnAboutNonPOD = false;
+    
+    // FIXME: Dependent case loses a lot of information here. And probably
+    // leaks like a sieve.
+    for (unsigned i = 0; i != NumComponents; ++i) {
+      const OffsetOfComponent &OC = CompPtr[i];
+      if (OC.isBrackets) {
+        // Offset of an array sub-field.  TODO: Should we allow vector elements?
+        const ArrayType *AT = Context.getAsArrayType(Res->getType());
+        if (!AT) {
+          Res->Destroy(Context);
+          return ExprError(Diag(OC.LocEnd, diag::err_offsetof_array_type)
+            << Res->getType());
+        }
+
+        // FIXME: C++: Verify that operator[] isn't overloaded.
+
+        // Promote the array so it looks more like a normal array subscript
+        // expression.
+        DefaultFunctionArrayConversion(Res);
+
+        // C99 6.5.2.1p1
+        Expr *Idx = static_cast<Expr*>(OC.U.E);
+        // FIXME: Leaks Res
+        if (!Idx->isTypeDependent() && !Idx->getType()->isIntegerType())
+          return ExprError(Diag(Idx->getLocStart(),
+                                diag::err_typecheck_subscript_not_integer)
+            << Idx->getSourceRange());
+
+        Res = new (Context) ArraySubscriptExpr(Res, Idx, AT->getElementType(),
+                                               OC.LocEnd);
+        continue;
+      }
+
+      const RecordType *RC = Res->getType()->getAsRecordType();
+      if (!RC) {
+        Res->Destroy(Context);
+        return ExprError(Diag(OC.LocEnd, diag::err_offsetof_record_type)
+          << Res->getType());
+      }
+
+      // Get the decl corresponding to this.
+      RecordDecl *RD = RC->getDecl();
+      if (CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
+        if (!CRD->isPOD() && !DidWarnAboutNonPOD) {
+          ExprError(Diag(BuiltinLoc, diag::warn_offsetof_non_pod_type)
+            << SourceRange(CompPtr[0].LocStart, OC.LocEnd)
+            << Res->getType());
+          DidWarnAboutNonPOD = true;
+        }
+      }
+      
+      FieldDecl *MemberDecl
+        = dyn_cast_or_null<FieldDecl>(LookupQualifiedName(RD, OC.U.IdentInfo,
+                                                          LookupMemberName)
+                                        .getAsDecl());
+      // FIXME: Leaks Res
+      if (!MemberDecl)
+        return ExprError(Diag(BuiltinLoc, diag::err_typecheck_no_member)
+         << OC.U.IdentInfo << SourceRange(OC.LocStart, OC.LocEnd));
+
+      // FIXME: C++: Verify that MemberDecl isn't a static field.
+      // FIXME: Verify that MemberDecl isn't a bitfield.
+      if (cast<RecordDecl>(MemberDecl->getDeclContext())->isAnonymousStructOrUnion()) {
+        Res = BuildAnonymousStructUnionMemberReference(
+            SourceLocation(), MemberDecl, Res, SourceLocation()).takeAs<Expr>();
+      } else {
+        // MemberDecl->getType() doesn't get the right qualifiers, but it
+        // doesn't matter here.
+        Res = new (Context) MemberExpr(Res, false, MemberDecl, OC.LocEnd,
+                MemberDecl->getType().getNonReferenceType());
+      }
+    }
+  }
+
+  return Owned(new (Context) UnaryOperator(Res, UnaryOperator::OffsetOf,
+                                           Context.getSizeType(), BuiltinLoc));
+}
+
+
+Sema::OwningExprResult Sema::ActOnTypesCompatibleExpr(SourceLocation BuiltinLoc,
+                                                      TypeTy *arg1,TypeTy *arg2,
+                                                      SourceLocation RPLoc) {
+  QualType argT1 = QualType::getFromOpaquePtr(arg1);
+  QualType argT2 = QualType::getFromOpaquePtr(arg2);
+
+  assert((!argT1.isNull() && !argT2.isNull()) && "Missing type argument(s)");
+
+  if (getLangOptions().CPlusPlus) {
+    Diag(BuiltinLoc, diag::err_types_compatible_p_in_cplusplus)
+      << SourceRange(BuiltinLoc, RPLoc);
+    return ExprError();
+  }
+
+  return Owned(new (Context) TypesCompatibleExpr(Context.IntTy, BuiltinLoc,
+                                                 argT1, argT2, RPLoc));
+}
+
+Sema::OwningExprResult Sema::ActOnChooseExpr(SourceLocation BuiltinLoc,
+                                             ExprArg cond,
+                                             ExprArg expr1, ExprArg expr2,
+                                             SourceLocation RPLoc) {
+  Expr *CondExpr = static_cast<Expr*>(cond.get());
+  Expr *LHSExpr = static_cast<Expr*>(expr1.get());
+  Expr *RHSExpr = static_cast<Expr*>(expr2.get());
+
+  assert((CondExpr && LHSExpr && RHSExpr) && "Missing type argument(s)");
+
+  QualType resType;
+  if (CondExpr->isTypeDependent() || CondExpr->isValueDependent()) {
+    resType = Context.DependentTy;
+  } else {
+    // The conditional expression is required to be a constant expression.
+    llvm::APSInt condEval(32);
+    SourceLocation ExpLoc;
+    if (!CondExpr->isIntegerConstantExpr(condEval, Context, &ExpLoc))
+      return ExprError(Diag(ExpLoc,
+                       diag::err_typecheck_choose_expr_requires_constant)
+        << CondExpr->getSourceRange());
+
+    // If the condition is > zero, then the AST type is the same as the LSHExpr.
+    resType = condEval.getZExtValue() ? LHSExpr->getType() : RHSExpr->getType();
+  }
+
+  cond.release(); expr1.release(); expr2.release();
+  return Owned(new (Context) ChooseExpr(BuiltinLoc, CondExpr, LHSExpr, RHSExpr,
+                                        resType, RPLoc));
+}
+
+//===----------------------------------------------------------------------===//
+// Clang Extensions.
+//===----------------------------------------------------------------------===//
+
+/// ActOnBlockStart - This callback is invoked when a block literal is started.
+void Sema::ActOnBlockStart(SourceLocation CaretLoc, Scope *BlockScope) {
+  // Analyze block parameters.
+  BlockSemaInfo *BSI = new BlockSemaInfo();
+
+  // Add BSI to CurBlock.
+  BSI->PrevBlockInfo = CurBlock;
+  CurBlock = BSI;
+
+  BSI->ReturnType = 0;
+  BSI->TheScope = BlockScope;
+  BSI->hasBlockDeclRefExprs = false;
+  BSI->SavedFunctionNeedsScopeChecking = CurFunctionNeedsScopeChecking;
+  CurFunctionNeedsScopeChecking = false;
+
+  BSI->TheDecl = BlockDecl::Create(Context, CurContext, CaretLoc);
+  PushDeclContext(BlockScope, BSI->TheDecl);
+}
+
+void Sema::ActOnBlockArguments(Declarator &ParamInfo, Scope *CurScope) {
+  assert(ParamInfo.getIdentifier()==0 && "block-id should have no identifier!");
+
+  if (ParamInfo.getNumTypeObjects() == 0
+      || ParamInfo.getTypeObject(0).Kind != DeclaratorChunk::Function) {
+    ProcessDeclAttributes(CurBlock->TheDecl, ParamInfo);
+    QualType T = GetTypeForDeclarator(ParamInfo, CurScope);
+
+    if (T->isArrayType()) {
+      Diag(ParamInfo.getSourceRange().getBegin(),
+           diag::err_block_returns_array);
+      return;
+    }
+
+    // The parameter list is optional, if there was none, assume ().
+    if (!T->isFunctionType())
+      T = Context.getFunctionType(T, NULL, 0, 0, 0);
+
+    CurBlock->hasPrototype = true;
+    CurBlock->isVariadic = false;
+    // Check for a valid sentinel attribute on this block.
+    if (CurBlock->TheDecl->getAttr<SentinelAttr>()) {
+      Diag(ParamInfo.getAttributes()->getLoc(), 
+           diag::warn_attribute_sentinel_not_variadic) << 1;
+      // FIXME: remove the attribute.
+    }
+    QualType RetTy = T.getTypePtr()->getAsFunctionType()->getResultType();
+    
+    // Do not allow returning a objc interface by-value.
+    if (RetTy->isObjCInterfaceType()) {
+      Diag(ParamInfo.getSourceRange().getBegin(),
+           diag::err_object_cannot_be_passed_returned_by_value) << 0 << RetTy;
+      return;
+    }
+    return;
+  }
+
+  // Analyze arguments to block.
+  assert(ParamInfo.getTypeObject(0).Kind == DeclaratorChunk::Function &&
+         "Not a function declarator!");
+  DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getTypeObject(0).Fun;
+
+  CurBlock->hasPrototype = FTI.hasPrototype;
+  CurBlock->isVariadic = true;
+
+  // Check for C99 6.7.5.3p10 - foo(void) is a non-varargs function that takes
+  // no arguments, not a function that takes a single void argument.
+  if (FTI.hasPrototype &&
+      FTI.NumArgs == 1 && !FTI.isVariadic && FTI.ArgInfo[0].Ident == 0 &&
+     (!FTI.ArgInfo[0].Param.getAs<ParmVarDecl>()->getType().getCVRQualifiers()&&
+        FTI.ArgInfo[0].Param.getAs<ParmVarDecl>()->getType()->isVoidType())) {
+    // empty arg list, don't push any params.
+    CurBlock->isVariadic = false;
+  } else if (FTI.hasPrototype) {
+    for (unsigned i = 0, e = FTI.NumArgs; i != e; ++i)
+      CurBlock->Params.push_back(FTI.ArgInfo[i].Param.getAs<ParmVarDecl>());
+    CurBlock->isVariadic = FTI.isVariadic;
+  }
+  CurBlock->TheDecl->setParams(Context, CurBlock->Params.data(),
+                               CurBlock->Params.size());
+  CurBlock->TheDecl->setIsVariadic(CurBlock->isVariadic);
+  ProcessDeclAttributes(CurBlock->TheDecl, ParamInfo);
+  for (BlockDecl::param_iterator AI = CurBlock->TheDecl->param_begin(),
+       E = CurBlock->TheDecl->param_end(); AI != E; ++AI)
+    // If this has an identifier, add it to the scope stack.
+    if ((*AI)->getIdentifier())
+      PushOnScopeChains(*AI, CurBlock->TheScope);
+
+  // Check for a valid sentinel attribute on this block.
+  if (!CurBlock->isVariadic && CurBlock->TheDecl->getAttr<SentinelAttr>()) {
+    Diag(ParamInfo.getAttributes()->getLoc(), 
+         diag::warn_attribute_sentinel_not_variadic) << 1;
+    // FIXME: remove the attribute.
+  }
+  
+  // Analyze the return type.
+  QualType T = GetTypeForDeclarator(ParamInfo, CurScope);
+  QualType RetTy = T->getAsFunctionType()->getResultType();
+  
+  // Do not allow returning a objc interface by-value.
+  if (RetTy->isObjCInterfaceType()) {
+    Diag(ParamInfo.getSourceRange().getBegin(),
+         diag::err_object_cannot_be_passed_returned_by_value) << 0 << RetTy;
+  } else if (!RetTy->isDependentType())
+    CurBlock->ReturnType = RetTy.getTypePtr();
+}
+
+/// ActOnBlockError - If there is an error parsing a block, this callback
+/// is invoked to pop the information about the block from the action impl.
+void Sema::ActOnBlockError(SourceLocation CaretLoc, Scope *CurScope) {
+  // Ensure that CurBlock is deleted.
+  llvm::OwningPtr<BlockSemaInfo> CC(CurBlock);
+
+  CurFunctionNeedsScopeChecking = CurBlock->SavedFunctionNeedsScopeChecking;
+
+  // Pop off CurBlock, handle nested blocks.
+  PopDeclContext();
+  CurBlock = CurBlock->PrevBlockInfo;
+  // FIXME: Delete the ParmVarDecl objects as well???
+}
+
+/// ActOnBlockStmtExpr - This is called when the body of a block statement
+/// literal was successfully completed.  ^(int x){...}
+Sema::OwningExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
+                                                StmtArg body, Scope *CurScope) {
+  // If blocks are disabled, emit an error.
+  if (!LangOpts.Blocks)
+    Diag(CaretLoc, diag::err_blocks_disable);
+  
+  // Ensure that CurBlock is deleted.
+  llvm::OwningPtr<BlockSemaInfo> BSI(CurBlock);
+
+  PopDeclContext();
+
+  // Pop off CurBlock, handle nested blocks.
+  CurBlock = CurBlock->PrevBlockInfo;
+
+  QualType RetTy = Context.VoidTy;
+  if (BSI->ReturnType)
+    RetTy = QualType(BSI->ReturnType, 0);
+
+  llvm::SmallVector<QualType, 8> ArgTypes;
+  for (unsigned i = 0, e = BSI->Params.size(); i != e; ++i)
+    ArgTypes.push_back(BSI->Params[i]->getType());
+
+  QualType BlockTy;
+  if (!BSI->hasPrototype)
+    BlockTy = Context.getFunctionNoProtoType(RetTy);
+  else
+    BlockTy = Context.getFunctionType(RetTy, ArgTypes.data(), ArgTypes.size(),
+                                      BSI->isVariadic, 0);
+
+  // FIXME: Check that return/parameter types are complete/non-abstract
+
+  BlockTy = Context.getBlockPointerType(BlockTy);
+
+  // If needed, diagnose invalid gotos and switches in the block.
+  if (CurFunctionNeedsScopeChecking)
+    DiagnoseInvalidJumps(static_cast<CompoundStmt*>(body.get()));
+  CurFunctionNeedsScopeChecking = BSI->SavedFunctionNeedsScopeChecking;
+  
+  BSI->TheDecl->setBody(body.takeAs<CompoundStmt>());
+  return Owned(new (Context) BlockExpr(BSI->TheDecl, BlockTy,
+                                       BSI->hasBlockDeclRefExprs));
+}
+
+Sema::OwningExprResult Sema::ActOnVAArg(SourceLocation BuiltinLoc,
+                                        ExprArg expr, TypeTy *type,
+                                        SourceLocation RPLoc) {
+  QualType T = QualType::getFromOpaquePtr(type);
+  Expr *E = static_cast<Expr*>(expr.get());
+  Expr *OrigExpr = E;
+  
+  InitBuiltinVaListType();
+
+  // Get the va_list type
+  QualType VaListType = Context.getBuiltinVaListType();
+  if (VaListType->isArrayType()) {
+    // Deal with implicit array decay; for example, on x86-64,
+    // va_list is an array, but it's supposed to decay to
+    // a pointer for va_arg.
+    VaListType = Context.getArrayDecayedType(VaListType);
+    // Make sure the input expression also decays appropriately.
+    UsualUnaryConversions(E);
+  } else {
+    // Otherwise, the va_list argument must be an l-value because
+    // it is modified by va_arg.
+    if (!E->isTypeDependent() && 
+        CheckForModifiableLvalue(E, BuiltinLoc, *this))
+      return ExprError();
+  }
+
+  if (!E->isTypeDependent() &&
+      !Context.hasSameType(VaListType, E->getType())) {
+    return ExprError(Diag(E->getLocStart(),
+                         diag::err_first_argument_to_va_arg_not_of_type_va_list)
+      << OrigExpr->getType() << E->getSourceRange());
+  }
+
+  // FIXME: Check that type is complete/non-abstract
+  // FIXME: Warn if a non-POD type is passed in.
+
+  expr.release();
+  return Owned(new (Context) VAArgExpr(BuiltinLoc, E, T.getNonReferenceType(),
+                                       RPLoc));
+}
+
+Sema::OwningExprResult Sema::ActOnGNUNullExpr(SourceLocation TokenLoc) {
+  // The type of __null will be int or long, depending on the size of
+  // pointers on the target.
+  QualType Ty;
+  if (Context.Target.getPointerWidth(0) == Context.Target.getIntWidth())
+    Ty = Context.IntTy;
+  else
+    Ty = Context.LongTy;
+
+  return Owned(new (Context) GNUNullExpr(Ty, TokenLoc));
+}
+
+bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
+                                    SourceLocation Loc,
+                                    QualType DstType, QualType SrcType,
+                                    Expr *SrcExpr, const char *Flavor) {
+  // Decode the result (notice that AST's are still created for extensions).
+  bool isInvalid = false;
+  unsigned DiagKind;
+  switch (ConvTy) {
+  default: assert(0 && "Unknown conversion type");
+  case Compatible: return false;
+  case PointerToInt:
+    DiagKind = diag::ext_typecheck_convert_pointer_int;
+    break;
+  case IntToPointer:
+    DiagKind = diag::ext_typecheck_convert_int_pointer;
+    break;
+  case IncompatiblePointer:
+    DiagKind = diag::ext_typecheck_convert_incompatible_pointer;
+    break;
+  case IncompatiblePointerSign:
+    DiagKind = diag::ext_typecheck_convert_incompatible_pointer_sign;
+    break;
+  case FunctionVoidPointer:
+    DiagKind = diag::ext_typecheck_convert_pointer_void_func;
+    break;
+  case CompatiblePointerDiscardsQualifiers:
+    // If the qualifiers lost were because we were applying the
+    // (deprecated) C++ conversion from a string literal to a char*
+    // (or wchar_t*), then there was no error (C++ 4.2p2).  FIXME:
+    // Ideally, this check would be performed in
+    // CheckPointerTypesForAssignment. However, that would require a
+    // bit of refactoring (so that the second argument is an
+    // expression, rather than a type), which should be done as part
+    // of a larger effort to fix CheckPointerTypesForAssignment for
+    // C++ semantics.
+    if (getLangOptions().CPlusPlus &&
+        IsStringLiteralToNonConstPointerConversion(SrcExpr, DstType))
+      return false;
+    DiagKind = diag::ext_typecheck_convert_discards_qualifiers;
+    break;
+  case IntToBlockPointer:
+    DiagKind = diag::err_int_to_block_pointer;
+    break;
+  case IncompatibleBlockPointer:
+    DiagKind = diag::err_typecheck_convert_incompatible_block_pointer;
+    break;
+  case IncompatibleObjCQualifiedId:
+    // FIXME: Diagnose the problem in ObjCQualifiedIdTypesAreCompatible, since
+    // it can give a more specific diagnostic.
+    DiagKind = diag::warn_incompatible_qualified_id;
+    break;
+  case IncompatibleVectors:
+    DiagKind = diag::warn_incompatible_vectors;
+    break;
+  case Incompatible:
+    DiagKind = diag::err_typecheck_convert_incompatible;
+    isInvalid = true;
+    break;
+  }
+
+  Diag(Loc, DiagKind) << DstType << SrcType << Flavor
+    << SrcExpr->getSourceRange();
+  return isInvalid;
+}
+
+bool Sema::VerifyIntegerConstantExpression(const Expr *E, llvm::APSInt *Result){
+  llvm::APSInt ICEResult;
+  if (E->isIntegerConstantExpr(ICEResult, Context)) {
+    if (Result)
+      *Result = ICEResult;
+    return false;
+  }
+
+  Expr::EvalResult EvalResult;
+
+  if (!E->Evaluate(EvalResult, Context) || !EvalResult.Val.isInt() ||
+      EvalResult.HasSideEffects) {
+    Diag(E->getExprLoc(), diag::err_expr_not_ice) << E->getSourceRange();
+
+    if (EvalResult.Diag) {
+      // We only show the note if it's not the usual "invalid subexpression"
+      // or if it's actually in a subexpression.
+      if (EvalResult.Diag != diag::note_invalid_subexpr_in_ice ||
+          E->IgnoreParens() != EvalResult.DiagExpr->IgnoreParens())
+        Diag(EvalResult.DiagLoc, EvalResult.Diag);
+    }
+
+    return true;
+  }
+
+  Diag(E->getExprLoc(), diag::ext_expr_not_ice) <<
+    E->getSourceRange();
+
+  if (EvalResult.Diag &&
+      Diags.getDiagnosticLevel(diag::ext_expr_not_ice) != Diagnostic::Ignored)
+    Diag(EvalResult.DiagLoc, EvalResult.Diag);
+
+  if (Result)
+    *Result = EvalResult.Val.getInt();
+  return false;
+}