[MSVC] 'property' with an empty array in array subscript expression.

[ABataev]

Summary

MSVC supports 'property' attribute and allows to apply it to the declaration of an empty array in a class or structure definition.
For example:

__declspec(property(get=GetX, put=PutX)) int x[];

The above statement indicates that x[] can be used with one or more array indices. In this case, i=p->x[a][b] will be turned into i=p->GetX(a, b), and p->x[a][b] = i will be turned into p->PutX(a, b, i);

[rnk]

I think fundamentally we are doing too much declspec property lowering in Sema. We might want to back up and figure out how to do it in IRGen. Right now we have bugs like this, which are probably more important than new functionality:
https://llvm.org/bugs/show_bug.cgi?id=24132

[ABataev]

In D13336#257628, @rnk wrote:

I think fundamentally we are doing too much declspec property lowering in Sema. We might want to back up and figure out how to do it in IRGen. Right now we have bugs like this, which are probably more important than new functionality:
https://llvm.org/bugs/show_bug.cgi?id=24132

Currently declspec property is represented as a member function call and does not keep info about property itself. Array subscripts exprs add arguments to this member function call and it must be built in Sema, so we could use an existing codegen for CallExprs.

[rnk]

I spent some time reading through the pseudo-object implementation in clang, but I still don't understand it. We should ask John if he can review this.

My gut feeling is that we shouldn't have a global DenseMap in Sema just for this. Should we have some other node, like an ObjCSubscriptRefExpr that describes this instead?

We need *some* AST for the as-written syntactic form. Can you send a dump of the AST for the test?

lib/Sema/SemaExpr.cpp

3947–3948

Will this affect the syntactic form of the expression?

test/CodeGenCXX/ms-property.cpp

32

Can you add a ++ test?

[rjmccall]

I agree with Reid that you should not be adding a DenseMap to Sema for this. Just build a SubscriptExpr for the syntactic form and have it yield an expression of pseudo-object type; or you can make your own AST node for it if that makes things easier.

[ABataev]

Update after review

[rjmccall]

Needs more tests.

1. Dependent template instantiation.
2. Non-dependent template instantiation.
3. Indexes which are themselves pseudo-objects.
4. Templated getters and setters.
5. Non-POD by-value argument types.

include/clang/AST/BuiltinTypes.def

253 ↗

(On Diff #37854)

Hmm. I don't think you need a new placeholder type. These subscripts are still an ordinary pseudo-object; you can load and store at any point. Instead, you should detect this case by the expression node used, which can either be an ArraySubscriptExpr or a new node if you find it necessary.

lib/Sema/SemaExpr.cpp

3946

I think what you should do here is:

1. Detect whether the base type has pseudo-object type.
2. If so, give the pseudo-object code a chance to work on the expression. In most cases, it will just load; but if the base is an MSPropertyRefExpr of array type, or an ArraySubscriptExpr, it can leave it alone.
3. If the pseudo-object code returned an expression that's still of pseudo-object type, just build an ArraySubscriptExpr of pseudo-object type after you've folded pseudo-objects in the index as well.

4132

Placeholders should never get here.

lib/Sema/SemaPseudoObject.cpp

1457–1458

Don't modify ArgExprs in buildGet or buildSet; you might need to build both, e.g. when building a compound assignment or inc/dec.

Since you need to copy into a new array anyway, you might as well accumulate them index expressions in stack order and then reverse them when adding them to this array.

[ABataev]

Update after review

[rjmccall]

include/clang/AST/ExprCXX.h

689

Please add to the comment here that this is a syntactic pseudo-object expression.

lib/Sema/SemaExpr.cpp

3938

Please factor this check so that it only does extra work when the base has placeholder type, and please extract a function to compute IsMSPropertySubscript.

lib/Sema/SemaPseudoObject.cpp

1409

This code will look slightly nicer and be slightly more efficient if you maintain the invariant that parens have been ignored on Base. That is, IgnoreParens here and when assigning in the loop, and then you can remove them from the type-checks.

Oh. You also need to capture the index expressions so that they aren't evaluated multiple times when this expression is used as the l-value of an increment, decrement, or compound-assignment. You then need to un-capture them in the Rebuilder. Please add code-generation tests that check that the index expression is only evaluated once in these cases.

[ABataev]

Update after review

[ABataev]

John, any comments?

[rjmccall]

lib/Sema/SemaPseudoObject.cpp

1603

Hmm. Just like the ObjCSubscriptRefExpr case, this will need to strip the OVEs off the index expressions, or else you'll end up stacking OVEs and asserting in IRGen.

The deeper problem here is that we have too much redundancy in all these places that have to walk over the different pseudo-object expressions. We can remove some of that by simplifying the design of Rebuilder, which is really over-engineered for its task. It should be fine to make it non-templated, merge all of the rebuildSpecific cases into it (and therefore remove all of the subclasses), and give it a callback to invoke at all the capture points in source order.

I think the callback can just be a llvm::function_ref<Expr*(Expr*, unsigned)>. The second parameter is the position of the capture point in source order, so for example in your case the base of the MSPropertyRefExpr will be 0, the index of the innermost MSPropertySubscriptExpr will be 1, and so on. That'll be important for callers that care about which capture point is which.

The various rebuildAndCaptureObject implementations should use a callback that returns the appropriate captured expression for the position.

stripOpaqueValuesFromPseudoObjectRef should use a callback that returns cast<OpaqueValueExpr>(e)->getSourceExpr(); it shouldn't need to split out the different cases at all.

[ABataev]

lib/Sema/SemaPseudoObject.cpp

1603

John, we don't need to strip the OVEs off the index expressions, because index expressions in MSPropertySubscriptExpr are not folded to OVEs. They are folded to OVEs only for CallArgs array. But in rebuilded MSPropertySubscriptExpr only base MSPropertyRefExpr is folded to OVE (we don't need to put indexes in MSPropertySubscriptExpr, because they are not used during codegen and we can keep original expressions). So, the code should work as is.
I reworked Rebuilder just like you said.

[rjmccall]

lib/Sema/SemaPseudoObject.cpp

59

Well, it should be okay to call this on something that doesn't have a base; it just doesn't need to do anything and can just return refExpr.

1603

That's what I'm saying, though: the capture process should be building the syntactic MSPropertySubscriptExpr using the captured OVEs for the index expressions as well as the recursively-captured base, and Rebuilder will then need to undo that.

We want to consistently replace all the captured sub-trees with their OVEs so that clients can easily recover the relationship between the syntactic and semantic forms.

1633

My hope is that you'll be able to get this whole function down to just this last line and won't need to split out any of the cases here.

[ABataev]

Update after review

[rjmccall]

This looks fantastic, thanks for doing all that. Approved with the one minor change.

lib/Sema/SemaPseudoObject.cpp

175

One extremely minor tweak: could you organize this like the rest of the pseudo-object expressions, checking for it above and calling a method to rebuild it?

[ABataev]

John, thanks a lot for the review!
Committed version has a fix according to your last comment.

include/clang/AST/ExprCXX.h

public:
   MSPropertyDecl *getPropertyDecl() const { return TheDecl; }
   bool isArrow() const { return IsArrow; }
   SourceLocation getMemberLoc() const { return MemberLoc; }
   NestedNameSpecifierLoc getQualifierLoc() const { return QualifierLoc; }
 
   friend class ASTStmtReader;
 };
 
+/// MS property subscript expression.
+/// MSVC supports 'property' attribute and allows to apply it to the
+/// declaration of an empty array in a class or structure definition.
+/// For example:
+/// \code
+/// __declspec(property(get=GetX, put=PutX)) int x[];
+/// \endcode
+/// The above statement indicates that x[] can be used with one or more array
+/// indices. In this case, i=p->x[a][b] will be turned into i=p->GetX(a, b), and
+/// p->x[a][b] = i will be turned into p->PutX(a, b, i).
+/// This is a syntactic pseudo-object expression.
+class MSPropertySubscriptExpr : public Expr {
+  friend class ASTStmtReader;
+  enum { BASE_EXPR, IDX_EXPR, NUM_SUBEXPRS = 2 };
+  Stmt *SubExprs[NUM_SUBEXPRS];
+  SourceLocation RBracketLoc;
+
+  void setBase(Expr *Base) { SubExprs[BASE_EXPR] = Base; }
+  void setIdx(Expr *Idx) { SubExprs[IDX_EXPR] = Idx; }
+
+public:
+  MSPropertySubscriptExpr(Expr *Base, Expr *Idx, QualType Ty, ExprValueKind VK,
+                          ExprObjectKind OK, SourceLocation RBracketLoc)
+      : Expr(MSPropertySubscriptExprClass, Ty, VK, OK, Idx->isTypeDependent(),
+             Idx->isValueDependent(), Idx->isInstantiationDependent(),
+             Idx->containsUnexpandedParameterPack()),
+        RBracketLoc(RBracketLoc) {
+    SubExprs[BASE_EXPR] = Base;
+    SubExprs[IDX_EXPR] = Idx;
+  }
+
+  /// \brief Create an empty array subscript expression.
+  explicit MSPropertySubscriptExpr(EmptyShell Shell)
+      : Expr(MSPropertySubscriptExprClass, Shell) {}
+
+  Expr *getBase() { return cast<Expr>(SubExprs[BASE_EXPR]); }
+  const Expr *getBase() const { return cast<Expr>(SubExprs[BASE_EXPR]); }
+
+  Expr *getIdx() { return cast<Expr>(SubExprs[IDX_EXPR]); }
+  const Expr *getIdx() const { return cast<Expr>(SubExprs[IDX_EXPR]); }
+
+  SourceLocation getLocStart() const LLVM_READONLY {
+    return getBase()->getLocStart();
+  }
+  SourceLocation getLocEnd() const LLVM_READONLY { return RBracketLoc; }
+
+  SourceLocation getRBracketLoc() const { return RBracketLoc; }
+  void setRBracketLoc(SourceLocation L) { RBracketLoc = L; }
+
+  SourceLocation getExprLoc() const LLVM_READONLY {
+    return getBase()->getExprLoc();
+  }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == MSPropertySubscriptExprClass;
+  }
+
+  // Iterators
+  child_range children() {
+    return child_range(&SubExprs[0], &SubExprs[0] + NUM_SUBEXPRS);
+  }
+};
+
 /// A Microsoft C++ @c __uuidof expression, which gets
 /// the _GUID that corresponds to the supplied type or expression.
 ///
 /// This represents code like @c __uuidof(COMTYPE) or @c __uuidof(*comPtr)
 class CXXUuidofExpr : public Expr {
 private:
   llvm::PointerUnion<Stmt *, TypeSourceInfo *> Operand;
   SourceRange Range;

include/clang/AST/RecursiveASTVisitor.h

DEF_TRAVERSE_STMT(CXXTypeidExpr, {
   if (S->isTypeOperand())
     TRY_TO(TraverseTypeLoc(S->getTypeOperandSourceInfo()->getTypeLoc()));
 })
 
 DEF_TRAVERSE_STMT(MSPropertyRefExpr, {
   TRY_TO(TraverseNestedNameSpecifierLoc(S->getQualifierLoc()));
 })
 
+DEF_TRAVERSE_STMT(MSPropertySubscriptExpr, {})
+
 DEF_TRAVERSE_STMT(CXXUuidofExpr, {
   // The child-iterator will pick up the arg if it's an expression,
   // but not if it's a type.
   if (S->isTypeOperand())
     TRY_TO(TraverseTypeLoc(S->getTypeOperandSourceInfo()->getTypeLoc()));
 })
 
 DEF_TRAVERSE_STMT(TypeTraitExpr, {

include/clang/Basic/StmtNodes.td

 def ShuffleVectorExpr : DStmt<Expr>;
 def ConvertVectorExpr : DStmt<Expr>;
 def BlockExpr : DStmt<Expr>;
 def OpaqueValueExpr : DStmt<Expr>;
 def TypoExpr : DStmt<Expr>;
 
 // Microsoft Extensions.
 def MSPropertyRefExpr : DStmt<Expr>;
+def MSPropertySubscriptExpr : DStmt<Expr>;
 def CXXUuidofExpr : DStmt<Expr>; 
 def SEHTryStmt : Stmt;
 def SEHExceptStmt : Stmt;
 def SEHFinallyStmt : Stmt;
 def SEHLeaveStmt : Stmt;
 def MSDependentExistsStmt : Stmt;
 
 // OpenCL Extensions.

include/clang/Serialization/ASTBitCodes.h

enum StmtCode {
       // CUDA
       EXPR_CUDA_KERNEL_CALL,       // CUDAKernelCallExpr      
 
       // OpenCL
       EXPR_ASTYPE,                 // AsTypeExpr
 
       // Microsoft
       EXPR_CXX_PROPERTY_REF_EXPR, // MSPropertyRefExpr
+      EXPR_CXX_PROPERTY_SUBSCRIPT_EXPR, // MSPropertySubscriptExpr
       EXPR_CXX_UUIDOF_EXPR,       // CXXUuidofExpr (of expr).
       EXPR_CXX_UUIDOF_TYPE,       // CXXUuidofExpr (of type).
       STMT_SEH_LEAVE,             // SEHLeaveStmt
       STMT_SEH_EXCEPT,            // SEHExceptStmt
       STMT_SEH_FINALLY,           // SEHFinallyStmt
       STMT_SEH_TRY,               // SEHTryStmt
 
       // OpenMP directives

lib/AST/Expr.cpp

bool Expr::HasSideEffects(const ASTContext &Ctx,
 
   case BlockExprClass:
   case CXXBindTemporaryExprClass:
     if (!IncludePossibleEffects)
       break;
     return true;
 
   case MSPropertyRefExprClass:
+  case MSPropertySubscriptExprClass:
   case CompoundAssignOperatorClass:
   case VAArgExprClass:
   case AtomicExprClass:
   case CXXThrowExprClass:
   case CXXNewExprClass:
   case CXXDeleteExprClass:
   case ExprWithCleanupsClass:
   case CoawaitExprClass:

lib/AST/ExprClassification.cpp

#include "clang/AST/StmtNodes.inc"
   case Expr::TypoExprClass:
   case Expr::CXXDependentScopeMemberExprClass:
   case Expr::DependentScopeDeclRefExprClass:
     // ObjC instance variables are lvalues
     // FIXME: ObjC++0x might have different rules
   case Expr::ObjCIvarRefExprClass:
   case Expr::FunctionParmPackExprClass:
   case Expr::MSPropertyRefExprClass:
+  case Expr::MSPropertySubscriptExprClass:
   case Expr::OMPArraySectionExprClass:
     return Cl::CL_LValue;
 
     // C99 6.5.2.5p5 says that compound literals are lvalues.
     // In C++, they're prvalue temporaries.
   case Expr::CompoundLiteralExprClass:
     return Ctx.getLangOpts().CPlusPlus ? ClassifyTemporary(E->getType())
                                        : Cl::CL_LValue;

lib/AST/ExprConstant.cpp

#include "clang/AST/StmtNodes.inc"
   case Expr::AddrLabelExprClass:
   case Expr::StmtExprClass:
   case Expr::CXXMemberCallExprClass:
   case Expr::CUDAKernelCallExprClass:
   case Expr::CXXDynamicCastExprClass:
   case Expr::CXXTypeidExprClass:
   case Expr::CXXUuidofExprClass:
   case Expr::MSPropertyRefExprClass:
+  case Expr::MSPropertySubscriptExprClass:
   case Expr::CXXNullPtrLiteralExprClass:
   case Expr::UserDefinedLiteralClass:
   case Expr::CXXThisExprClass:
   case Expr::CXXThrowExprClass:
   case Expr::CXXNewExprClass:
   case Expr::CXXDeleteExprClass:
   case Expr::CXXPseudoDestructorExprClass:
   case Expr::UnresolvedLookupExprClass:

lib/AST/ItaniumMangle.cpp

#include "clang/AST/StmtNodes.inc"
   // contexts and so should never appear in a mangling.
   case Expr::AddrLabelExprClass:
   case Expr::DesignatedInitUpdateExprClass:
   case Expr::ImplicitValueInitExprClass:
   case Expr::NoInitExprClass:
   case Expr::ParenListExprClass:
   case Expr::LambdaExprClass:
   case Expr::MSPropertyRefExprClass:
+  case Expr::MSPropertySubscriptExprClass:
   case Expr::TypoExprClass:  // This should no longer exist in the AST by now.
   case Expr::OMPArraySectionExprClass:
     llvm_unreachable("unexpected statement kind");
 
   // FIXME: invent manglings for all these.
   case Expr::BlockExprClass:
   case Expr::ChooseExprClass:
   case Expr::CompoundLiteralExprClass:

lib/AST/StmtPrinter.cpp

void StmtPrinter::VisitMSPropertyRefExpr(MSPropertyRefExpr *Node) {
   else
     OS << ".";
   if (NestedNameSpecifier *Qualifier =
       Node->getQualifierLoc().getNestedNameSpecifier())
     Qualifier->print(OS, Policy);
   OS << Node->getPropertyDecl()->getDeclName();
 }
 
+void StmtPrinter::VisitMSPropertySubscriptExpr(MSPropertySubscriptExpr *Node) {
+  PrintExpr(Node->getBase());
+  OS << "[";
+  PrintExpr(Node->getIdx());
+  OS << "]";
+}
+
 void StmtPrinter::VisitUserDefinedLiteral(UserDefinedLiteral *Node) {
   switch (Node->getLiteralOperatorKind()) {
   case UserDefinedLiteral::LOK_Raw:
     OS << cast<StringLiteral>(Node->getArg(0)->IgnoreImpCasts())->getString();
     break;
   case UserDefinedLiteral::LOK_Template: {
     DeclRefExpr *DRE = cast<DeclRefExpr>(Node->getCallee()->IgnoreImpCasts());
     const TemplateArgumentList *Args =

lib/AST/StmtProfile.cpp

if (S->isTypeOperand())
     VisitType(S->getTypeOperandSourceInfo()->getType());
 }
 
 void StmtProfiler::VisitMSPropertyRefExpr(const MSPropertyRefExpr *S) {
   VisitExpr(S);
   VisitDecl(S->getPropertyDecl());
 }
 
+void StmtProfiler::VisitMSPropertySubscriptExpr(
+    const MSPropertySubscriptExpr *S) {
+  VisitExpr(S);
+}
+
 void StmtProfiler::VisitCXXThisExpr(const CXXThisExpr *S) {
   VisitExpr(S);
   ID.AddBoolean(S->isImplicit());
 }
 
 void StmtProfiler::VisitCXXThrowExpr(const CXXThrowExpr *S) {
   VisitExpr(S);
 }

lib/Sema/SemaExceptionSpec.cpp

CanThrowResult Sema::canThrow(const Expr *E) {
   case Expr::OpaqueValueExprClass:
   case Expr::PredefinedExprClass:
   case Expr::SizeOfPackExprClass:
   case Expr::StringLiteralClass:
     // These expressions can never throw.
     return CT_Cannot;
 
   case Expr::MSPropertyRefExprClass:
+  case Expr::MSPropertySubscriptExprClass:
     llvm_unreachable("Invalid class for expression");
 
 #define STMT(CLASS, PARENT) case Expr::CLASS##Class:
 #define STMT_RANGE(Base, First, Last)
 #define LAST_STMT_RANGE(BASE, FIRST, LAST)
 #define EXPR(CLASS, PARENT)
 #define ABSTRACT_STMT(STMT)
 #include "clang/AST/StmtNodes.inc"
   case Expr::NoStmtClass:
     llvm_unreachable("Invalid class for expression");
   }
   llvm_unreachable("Bogus StmtClass");
 }
 
 } // end namespace clang

lib/Sema/SemaExpr.cpp

if (S.LangOpts.ObjCRuntime.allowsPointerArithmetic() &&
     return false;
 
   S.Diag(opLoc, diag::err_arithmetic_nonfragile_interface)
     << op->getType()->castAs<ObjCObjectPointerType>()->getPointeeType()
     << op->getSourceRange();
   return true;
 }
 
+static bool isMSPropertySubscriptExpr(Sema &S, Expr *Base) {
+  auto *BaseNoParens = Base->IgnoreParens();
+  if (auto *MSProp = dyn_cast<MSPropertyRefExpr>(BaseNoParens))
+    return MSProp->getPropertyDecl()->getType()->isArrayType();
+  return isa<MSPropertySubscriptExpr>(BaseNoParens);
+}
+
 ExprResult
 Sema::ActOnArraySubscriptExpr(Scope *S, Expr *base, SourceLocation lbLoc,
                               Expr *idx, SourceLocation rbLoc) {
   if (base && !base->getType().isNull() &&
       base->getType()->isSpecificPlaceholderType(BuiltinType::OMPArraySection))
     return ActOnOMPArraySectionExpr(base, lbLoc, idx, SourceLocation(),
                                     /*Length=*/nullptr, rbLoc);
 
   // Since this might be a postfix expression, get rid of ParenListExprs.
   if (isa<ParenListExpr>(base)) {
     ExprResult result = MaybeConvertParenListExprToParenExpr(S, base);
     if (result.isInvalid()) return ExprError();
     base = result.get();
   }
 
   // Handle any non-overload placeholder types in the base and index
   // expressions.  We can't handle overloads here because the other
   // operand might be an overloadable type, in which case the overload
   // resolution for the operator overload should get the first crack
   // at the overload.
+  bool IsMSPropertySubscript = false;
   if (base->getType()->isNonOverloadPlaceholderType()) {
+    IsMSPropertySubscript = isMSPropertySubscriptExpr(*this, base);
+    if (!IsMSPropertySubscript) {
       ExprResult result = CheckPlaceholderExpr(base);
-    if (result.isInvalid()) return ExprError();
+      if (result.isInvalid())
+        return ExprError();
       base = result.get();
     }
+  }
   if (idx->getType()->isNonOverloadPlaceholderType()) {
     ExprResult result = CheckPlaceholderExpr(idx);
     if (result.isInvalid()) return ExprError();
     idx = result.get();
   }
 
   // Build an unanalyzed expression if either operand is type-dependent.
   if (getLangOpts().CPlusPlus &&
       (base->isTypeDependent() || idx->isTypeDependent())) {
     return new (Context) ArraySubscriptExpr(base, idx, Context.DependentTy,
                                             VK_LValue, OK_Ordinary, rbLoc);
   }
 
+  // MSDN, property (C++)
+  // https://msdn.microsoft.com/en-us/library/yhfk0thd(v=vs.120).aspx
+  // This attribute can also be used in the declaration of an empty array in a
+  // class or structure definition. For example:
+  // __declspec(property(get=GetX, put=PutX)) int x[];
+  // The above statement indicates that x[] can be used with one or more array
+  // indices. In this case, i=p->x[a][b] will be turned into i=p->GetX(a, b),
+  // and p->x[a][b] = i will be turned into p->PutX(a, b, i);
+  if (IsMSPropertySubscript) {
+    // Build MS property subscript expression if base is MS property reference
+    // or MS property subscript.
+    return new (Context) MSPropertySubscriptExpr(
+        base, idx, Context.PseudoObjectTy, VK_LValue, OK_Ordinary, rbLoc);
+  }
+
   // Use C++ overloaded-operator rules if either operand has record
   // type.  The spec says to do this if either type is *overloadable*,
   // but enum types can't declare subscript operators or conversion
   // operators, so there's nothing interesting for overload resolution
   // to do if there aren't any record types involved.
   //
   // ObjC pointers have their own subscripting logic that is not tied
   // to overload resolution and so should not take this path.
Sema::CreateBuiltinArraySubscriptExpr(Expr *Base, SourceLocation LLoc,
   Expr *RHSExp = Idx;
 
   // Perform default conversions.
   if (!LHSExp->getType()->getAs<VectorType>()) {
     ExprResult Result = DefaultFunctionArrayLvalueConversion(LHSExp);
     if (Result.isInvalid())
       return ExprError();
     LHSExp = Result.get();
   }
   ExprResult Result = DefaultFunctionArrayLvalueConversion(RHSExp);
   if (Result.isInvalid())
     return ExprError();
   RHSExp = Result.get();
 
   QualType LHSTy = LHSExp->getType(), RHSTy = RHSExp->getType();
   ExprValueKind VK = VK_LValue;
   ExprObjectKind OK = OK_Ordinary;

lib/Sema/SemaPseudoObject.cpp

 #include "clang/Sema/ScopeInfo.h"
 #include "llvm/ADT/SmallString.h"
 
 using namespace clang;
 using namespace sema;
 
 namespace {
   // Basically just a very focused copy of TreeTransform.
-  template <class T> struct Rebuilder {
+  struct Rebuilder {
     Sema &S;
-    Rebuilder(Sema &S) : S(S) {}
+    unsigned MSPropertySubscriptCount;
+    typedef llvm::function_ref<Expr *(Expr *, unsigned)> SpecificRebuilderRefTy;
+    const SpecificRebuilderRefTy &SpecificCallback;
+    Rebuilder(Sema &S, const SpecificRebuilderRefTy &SpecificCallback)
+        : S(S), MSPropertySubscriptCount(0),
+          SpecificCallback(SpecificCallback) {}
 
-    T &getDerived() { return static_cast<T&>(*this); }
+    Expr *rebuildObjCPropertyRefExpr(ObjCPropertyRefExpr *refExpr) {
+      // Fortunately, the constraint that we're rebuilding something
+      // with a base limits the number of cases here.
+      if (refExpr->isClassReceiver() || refExpr->isSuperReceiver())
+        return refExpr;
+
+      if (refExpr->isExplicitProperty()) {
+        return new (S.Context) ObjCPropertyRefExpr(
+            refExpr->getExplicitProperty(), refExpr->getType(),
+            refExpr->getValueKind(), refExpr->getObjectKind(),
+            refExpr->getLocation(), SpecificCallback(refExpr->getBase(), 0));
+      }
+      return new (S.Context) ObjCPropertyRefExpr(
+          refExpr->getImplicitPropertyGetter(),
+          refExpr->getImplicitPropertySetter(), refExpr->getType(),
+          refExpr->getValueKind(), refExpr->getObjectKind(),
+          refExpr->getLocation(), SpecificCallback(refExpr->getBase(), 0));
+    }
+    Expr *rebuildObjCSubscriptRefExpr(ObjCSubscriptRefExpr *refExpr) {
+      assert(refExpr->getBaseExpr());
+      assert(refExpr->getKeyExpr());
+
+      return new (S.Context) ObjCSubscriptRefExpr(
+          SpecificCallback(refExpr->getBaseExpr(), 0),
+          SpecificCallback(refExpr->getKeyExpr(), 1), refExpr->getType(),
+          refExpr->getValueKind(), refExpr->getObjectKind(),
+          refExpr->getAtIndexMethodDecl(), refExpr->setAtIndexMethodDecl(),
+          refExpr->getRBracket());
+    }
+    Expr *rebuildMSPropertyRefExpr(MSPropertyRefExpr *refExpr) {
+      assert(refExpr->getBaseExpr());
+
+      return new (S.Context) MSPropertyRefExpr(
+          SpecificCallback(refExpr->getBaseExpr(), 0),
+          refExpr->getPropertyDecl(), refExpr->isArrow(), refExpr->getType(),
+          refExpr->getValueKind(), refExpr->getQualifierLoc(),
+          refExpr->getMemberLoc());
+    }
 
     Expr *rebuild(Expr *e) {
       // Fast path: nothing to look through.
-      if (typename T::specific_type *specific
-            = dyn_cast<typename T::specific_type>(e))
-        return getDerived().rebuildSpecific(specific);
+      if (auto *PRE = dyn_cast<ObjCPropertyRefExpr>(e))
+        return rebuildObjCPropertyRefExpr(PRE);
+      else if (auto *SRE = dyn_cast<ObjCSubscriptRefExpr>(e))
+        return rebuildObjCSubscriptRefExpr(SRE);
+      else if (auto *MSPRE = dyn_cast<MSPropertyRefExpr>(e))
+        return rebuildMSPropertyRefExpr(MSPRE);
 
       // Otherwise, we should look through and rebuild anything that
       // IgnoreParens would.
 
       if (ParenExpr *parens = dyn_cast<ParenExpr>(e)) {
         e = rebuild(parens->getSubExpr());
         return new (S.Context) ParenExpr(parens->getLParen(),
                                          parens->getRParen(),
Expr *rebuild(Expr *e) {
                                           rebuiltExpr->getValueKind(),
                                           rebuiltExpr->getObjectKind(),
                                           ce->getRParenLoc(),
                                           ce->isConditionTrue(),
                                           rebuiltExpr->isTypeDependent(),
                                           rebuiltExpr->isValueDependent());
       }
 
-      llvm_unreachable("bad expression to rebuild!");
-    }
-  };
-
-  struct ObjCPropertyRefRebuilder : Rebuilder<ObjCPropertyRefRebuilder> {
-    Expr *NewBase;
-    ObjCPropertyRefRebuilder(Sema &S, Expr *newBase)
-      : Rebuilder<ObjCPropertyRefRebuilder>(S), NewBase(newBase) {}
-
-    typedef ObjCPropertyRefExpr specific_type;
-    Expr *rebuildSpecific(ObjCPropertyRefExpr *refExpr) {
-      // Fortunately, the constraint that we're rebuilding something
-      // with a base limits the number of cases here.
-      assert(refExpr->isObjectReceiver());
-
-      if (refExpr->isExplicitProperty()) {
-        return new (S.Context)
-          ObjCPropertyRefExpr(refExpr->getExplicitProperty(),
-                              refExpr->getType(), refExpr->getValueKind(),
-                              refExpr->getObjectKind(), refExpr->getLocation(),
-                              NewBase);
-      }
-      return new (S.Context)
-        ObjCPropertyRefExpr(refExpr->getImplicitPropertyGetter(),
-                            refExpr->getImplicitPropertySetter(),
-                            refExpr->getType(), refExpr->getValueKind(),
-                            refExpr->getObjectKind(),refExpr->getLocation(),
-                            NewBase);
-    }
-  };
-
-  struct ObjCSubscriptRefRebuilder : Rebuilder<ObjCSubscriptRefRebuilder> {
-    Expr *NewBase;
-    Expr *NewKeyExpr;
-    ObjCSubscriptRefRebuilder(Sema &S, Expr *newBase, Expr *newKeyExpr)
-    : Rebuilder<ObjCSubscriptRefRebuilder>(S), 
-      NewBase(newBase), NewKeyExpr(newKeyExpr) {}
-    
-    typedef ObjCSubscriptRefExpr specific_type;
-    Expr *rebuildSpecific(ObjCSubscriptRefExpr *refExpr) {
-      assert(refExpr->getBaseExpr());
-      assert(refExpr->getKeyExpr());
-      
-      return new (S.Context)
-        ObjCSubscriptRefExpr(NewBase,
-                             NewKeyExpr,
-                             refExpr->getType(), refExpr->getValueKind(),
-                             refExpr->getObjectKind(),refExpr->getAtIndexMethodDecl(),
-                             refExpr->setAtIndexMethodDecl(),
-                             refExpr->getRBracket());
+      if (MSPropertySubscriptExpr *PSE = dyn_cast<MSPropertySubscriptExpr>(e)) {
+        auto *NewBase = rebuild(PSE->getBase());
+        ++MSPropertySubscriptCount;
+        return new (S.Context) MSPropertySubscriptExpr(
+            NewBase, SpecificCallback(PSE->getIdx(), MSPropertySubscriptCount),
+            PSE->getType(), PSE->getValueKind(), PSE->getObjectKind(),
+            PSE->getRBracketLoc());
       }
-  };
-
-  struct MSPropertyRefRebuilder : Rebuilder<MSPropertyRefRebuilder> {
-    Expr *NewBase;
-    MSPropertyRefRebuilder(Sema &S, Expr *newBase)
-    : Rebuilder<MSPropertyRefRebuilder>(S), NewBase(newBase) {}
-
-    typedef MSPropertyRefExpr specific_type;
-    Expr *rebuildSpecific(MSPropertyRefExpr *refExpr) {
-      assert(refExpr->getBaseExpr());
 
-      return new (S.Context)
-        MSPropertyRefExpr(NewBase, refExpr->getPropertyDecl(),
-                       refExpr->isArrow(), refExpr->getType(),
-                       refExpr->getValueKind(), refExpr->getQualifierLoc(),
-                       refExpr->getMemberLoc());
+      llvm_unreachable("bad expression to rebuild!");
     }
   };
-  
   class PseudoOpBuilder {
   public:
     Sema &S;
     unsigned ResultIndex;
     SourceLocation GenericLoc;
     SmallVector<Expr *, 4> Semantics;
 
     PseudoOpBuilder(Sema &S, SourceLocation genericLoc)
public:
 
    ExprResult buildGet() override;
    ExprResult buildSet(Expr *op, SourceLocation, bool) override;
  };
 
  class MSPropertyOpBuilder : public PseudoOpBuilder {
    MSPropertyRefExpr *RefExpr;
    OpaqueValueExpr *InstanceBase;
+   SmallVector<Expr *, 4> CallArgs;
+
+   MSPropertyRefExpr *getBaseMSProperty(MSPropertySubscriptExpr *E);
 
  public:
    MSPropertyOpBuilder(Sema &S, MSPropertyRefExpr *refExpr) :
      PseudoOpBuilder(S, refExpr->getSourceRange().getBegin()),
      RefExpr(refExpr), InstanceBase(nullptr) {}
+   MSPropertyOpBuilder(Sema &S, MSPropertySubscriptExpr *refExpr)
+       : PseudoOpBuilder(S, refExpr->getSourceRange().getBegin()),
+         InstanceBase(nullptr) {
+     RefExpr = getBaseMSProperty(refExpr);
+   }
 
    Expr *rebuildAndCaptureObject(Expr *) override;
    ExprResult buildGet() override;
    ExprResult buildSet(Expr *op, SourceLocation, bool) override;
  };
 }
 
 /// Capture the given expression in an OpaqueValueExpr.

 /// Capture the base object of an Objective-C property expression.
 Expr *ObjCPropertyOpBuilder::rebuildAndCaptureObject(Expr *syntacticBase) {
   assert(InstanceReceiver == nullptr);
 
   // If we have a base, capture it in an OVE and rebuild the syntactic
   // form to use the OVE as its base.
   if (RefExpr->isObjectReceiver()) {
     InstanceReceiver = capture(RefExpr->getBase());
-
-    syntacticBase =
-      ObjCPropertyRefRebuilder(S, InstanceReceiver).rebuild(syntacticBase);
+    syntacticBase = Rebuilder(S, [=](Expr *, unsigned) -> Expr * {
+                      return InstanceReceiver;
+                    }).rebuild(syntacticBase);
   }
 
   if (ObjCPropertyRefExpr *
         refE = dyn_cast<ObjCPropertyRefExpr>(syntacticBase->IgnoreParens()))
     SyntacticRefExpr = refE;
 
   return syntacticBase;
 }

 /// Capture the base object of an Objective-C Index'ed expression.
 Expr *ObjCSubscriptOpBuilder::rebuildAndCaptureObject(Expr *syntacticBase) {
   assert(InstanceBase == nullptr);
 
   // Capture base expression in an OVE and rebuild the syntactic
   // form to use the OVE as its base expression.
   InstanceBase = capture(RefExpr->getBaseExpr());
   InstanceKey = capture(RefExpr->getKeyExpr());
-    
   syntacticBase =
-    ObjCSubscriptRefRebuilder(S, InstanceBase, 
-                              InstanceKey).rebuild(syntacticBase);
-  
+      Rebuilder(S, [=](Expr *, unsigned Idx) -> Expr * {
+        switch (Idx) {
+        case 0:
+          return InstanceBase;
+        case 1:
+          return InstanceKey;
+        default:
+          llvm_unreachable("Unexpected index for ObjCSubscriptExpr");
+        }
+      }).rebuild(syntacticBase);
   return syntacticBase;
 }
 
 /// CheckSubscriptingKind - This routine decide what type 
 /// of indexing represented by "FromE" is being done.
 Sema::ObjCSubscriptKind 
   Sema::CheckSubscriptingKind(Expr *FromE) {
   // If the expression already has integral or enumeration type, we're golden.
ExprResult ObjCSubscriptOpBuilder::buildSet(Expr *op, SourceLocation opcLoc,
   
   return msg;
 }
 
 //===----------------------------------------------------------------------===//
 //  MSVC __declspec(property) references
 //===----------------------------------------------------------------------===//
 
+MSPropertyRefExpr *
+MSPropertyOpBuilder::getBaseMSProperty(MSPropertySubscriptExpr *E) {
+  CallArgs.insert(CallArgs.begin(), E->getIdx());
+  Expr *Base = E->getBase()->IgnoreParens();
+  while (auto *MSPropSubscript = dyn_cast<MSPropertySubscriptExpr>(Base)) {
+    CallArgs.insert(CallArgs.begin(), MSPropSubscript->getIdx());
+    Base = MSPropSubscript->getBase()->IgnoreParens();
+  }
+  return cast<MSPropertyRefExpr>(Base);
+}
+
 Expr *MSPropertyOpBuilder::rebuildAndCaptureObject(Expr *syntacticBase) {
   InstanceBase = capture(RefExpr->getBaseExpr());
-
-  syntacticBase =
-    MSPropertyRefRebuilder(S, InstanceBase).rebuild(syntacticBase);
+  std::for_each(CallArgs.begin(), CallArgs.end(),
+                [this](Expr *&Arg) { Arg = capture(Arg); });
+  syntacticBase = Rebuilder(S, [=](Expr *, unsigned Idx) -> Expr * {
+                    switch (Idx) {
+                    case 0:
+                      return InstanceBase;
+                    default:
+                      assert(Idx <= CallArgs.size());
+                      return CallArgs[Idx - 1];
+                    }
+                  }).rebuild(syntacticBase);
 
   return syntacticBase;
 }
 
 ExprResult MSPropertyOpBuilder::buildGet() {
   if (!RefExpr->getPropertyDecl()->hasGetter()) {
     S.Diag(RefExpr->getMemberLoc(), diag::err_no_accessor_for_property)
       << 0 /* getter */ << RefExpr->getPropertyDecl();
ExprResult GetterExpr =
                               RefExpr->isArrow() ? tok::arrow : tok::period, SS,
                               SourceLocation(), GetterName, nullptr);
   if (GetterExpr.isInvalid()) {
     S.Diag(RefExpr->getMemberLoc(),
            diag::error_cannot_find_suitable_accessor) << 0 /* getter */
       << RefExpr->getPropertyDecl();
     return ExprError();
   }
 
-  MultiExprArg ArgExprs;
   return S.ActOnCallExpr(S.getCurScope(), GetterExpr.get(),
-                         RefExpr->getSourceRange().getBegin(), ArgExprs,
+                         RefExpr->getSourceRange().getBegin(), CallArgs,
                          RefExpr->getSourceRange().getEnd());
 }
 
 ExprResult MSPropertyOpBuilder::buildSet(Expr *op, SourceLocation sl,
                                          bool captureSetValueAsResult) {
   if (!RefExpr->getPropertyDecl()->hasSetter()) {
     S.Diag(RefExpr->getMemberLoc(), diag::err_no_accessor_for_property)
       << 1 /* setter */ << RefExpr->getPropertyDecl();
ExprResult SetterExpr =
                               SourceLocation(), SetterName, nullptr);
   if (SetterExpr.isInvalid()) {
     S.Diag(RefExpr->getMemberLoc(),
            diag::error_cannot_find_suitable_accessor) << 1 /* setter */
       << RefExpr->getPropertyDecl();
     return ExprError();
   }
 
-  SmallVector<Expr*, 1> ArgExprs;
+  SmallVector<Expr*, 4> ArgExprs;
+  ArgExprs.append(CallArgs.begin(), CallArgs.end());
   ArgExprs.push_back(op);
   return S.ActOnCallExpr(S.getCurScope(), SetterExpr.get(),
                          RefExpr->getSourceRange().getBegin(), ArgExprs,
                          op->getSourceRange().getEnd());
 }
 
 //===----------------------------------------------------------------------===//
 //  General Sema routines.
ExprResult Sema::checkPseudoObjectRValue(Expr *E) {
   else if (ObjCSubscriptRefExpr *refExpr
            = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
     ObjCSubscriptOpBuilder builder(*this, refExpr);
     return builder.buildRValueOperation(E);
   } else if (MSPropertyRefExpr *refExpr
              = dyn_cast<MSPropertyRefExpr>(opaqueRef)) {
     MSPropertyOpBuilder builder(*this, refExpr);
     return builder.buildRValueOperation(E);
+  } else if (MSPropertySubscriptExpr *RefExpr =
+                 dyn_cast<MSPropertySubscriptExpr>(opaqueRef)) {
+    MSPropertyOpBuilder Builder(*this, RefExpr);
+    return Builder.buildRValueOperation(E);
   } else {
     llvm_unreachable("unknown pseudo-object kind!");
   }
 }
 
 /// Check an increment or decrement of a pseudo-object expression.
 ExprResult Sema::checkPseudoObjectIncDec(Scope *Sc, SourceLocation opcLoc,
                                          UnaryOperatorKind opcode, Expr *op) {
if (ObjCPropertyRefExpr *refExpr
     return builder.buildIncDecOperation(Sc, opcLoc, opcode, op);
   } else if (isa<ObjCSubscriptRefExpr>(opaqueRef)) {
     Diag(opcLoc, diag::err_illegal_container_subscripting_op);
     return ExprError();
   } else if (MSPropertyRefExpr *refExpr
              = dyn_cast<MSPropertyRefExpr>(opaqueRef)) {
     MSPropertyOpBuilder builder(*this, refExpr);
     return builder.buildIncDecOperation(Sc, opcLoc, opcode, op);
+  } else if (MSPropertySubscriptExpr *RefExpr
+             = dyn_cast<MSPropertySubscriptExpr>(opaqueRef)) {
+    MSPropertyOpBuilder Builder(*this, RefExpr);
+    return Builder.buildIncDecOperation(Sc, opcLoc, opcode, op);
   } else {
     llvm_unreachable("unknown pseudo-object kind!");
   }
 }
 
 ExprResult Sema::checkPseudoObjectAssignment(Scope *S, SourceLocation opcLoc,
                                              BinaryOperatorKind opcode,
                                              Expr *LHS, Expr *RHS) {
if (ObjCPropertyRefExpr *refExpr
     ObjCPropertyOpBuilder builder(*this, refExpr);
     return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
   } else if (ObjCSubscriptRefExpr *refExpr
              = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
     ObjCSubscriptOpBuilder builder(*this, refExpr);
     return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
   } else if (MSPropertyRefExpr *refExpr
              = dyn_cast<MSPropertyRefExpr>(opaqueRef)) {
       MSPropertyOpBuilder builder(*this, refExpr);
       return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
+  } else if (MSPropertySubscriptExpr *RefExpr
+             = dyn_cast<MSPropertySubscriptExpr>(opaqueRef)) {
+      MSPropertyOpBuilder Builder(*this, RefExpr);
+      return Builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
   } else {
     llvm_unreachable("unknown pseudo-object kind!");
   }
 }
 
 /// Given a pseudo-object reference, rebuild it without the opaque
 /// values.  Basically, undo the behavior of rebuildAndCaptureObject.
 /// This should never operate in-place.
 static Expr *stripOpaqueValuesFromPseudoObjectRef(Sema &S, Expr *E) {
-  Expr *opaqueRef = E->IgnoreParens();
-  if (ObjCPropertyRefExpr *refExpr
-        = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
-    // Class and super property references don't have opaque values in them.
-    if (refExpr->isClassReceiver() || refExpr->isSuperReceiver())
-      return E;
-    
-    assert(refExpr->isObjectReceiver() && "Unknown receiver kind?");
-    OpaqueValueExpr *baseOVE = cast<OpaqueValueExpr>(refExpr->getBase());
-    return ObjCPropertyRefRebuilder(S, baseOVE->getSourceExpr()).rebuild(E);
-  } else if (ObjCSubscriptRefExpr *refExpr
-               = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
-    OpaqueValueExpr *baseOVE = cast<OpaqueValueExpr>(refExpr->getBaseExpr());
-    OpaqueValueExpr *keyOVE = cast<OpaqueValueExpr>(refExpr->getKeyExpr());
-    return ObjCSubscriptRefRebuilder(S, baseOVE->getSourceExpr(), 
-                                     keyOVE->getSourceExpr()).rebuild(E);
-  } else if (MSPropertyRefExpr *refExpr
-             = dyn_cast<MSPropertyRefExpr>(opaqueRef)) {
-    OpaqueValueExpr *baseOVE = cast<OpaqueValueExpr>(refExpr->getBaseExpr());
-    return MSPropertyRefRebuilder(S, baseOVE->getSourceExpr()).rebuild(E);
-  } else {
-    llvm_unreachable("unknown pseudo-object kind!");
-  }
+  return Rebuilder(S,
+                   [=](Expr *E, unsigned) -> Expr * {
+                     return cast<OpaqueValueExpr>(E)->getSourceExpr();
+                   })
+      .rebuild(E);
 }
 
 /// Given a pseudo-object expression, recreate what it looks like
 /// syntactically without the attendant OpaqueValueExprs.
 ///
 /// This is a hack which should be removed when TreeTransform is
 /// capable of rebuilding a tree without stripping implicit
 /// operations.
 Expr *Sema::recreateSyntacticForm(PseudoObjectExpr *E) {
   Expr *syntax = E->getSyntacticForm();
   if (UnaryOperator *uop = dyn_cast<UnaryOperator>(syntax)) {
     Expr *op = stripOpaqueValuesFromPseudoObjectRef(*this, uop->getSubExpr());
     return new (Context) UnaryOperator(op, uop->getOpcode(), uop->getType(),
Expr *Sema::recreateSyntacticForm(PseudoObjectExpr *E) {
   } else if (BinaryOperator *bop = dyn_cast<BinaryOperator>(syntax)) {
     Expr *lhs = stripOpaqueValuesFromPseudoObjectRef(*this, bop->getLHS());
     Expr *rhs = cast<OpaqueValueExpr>(bop->getRHS())->getSourceExpr();
     return new (Context) BinaryOperator(lhs, rhs, bop->getOpcode(),
                                         bop->getType(), bop->getValueKind(),
                                         bop->getObjectKind(),
                                         bop->getOperatorLoc(), false);
   } else {
     assert(syntax->hasPlaceholderType(BuiltinType::PseudoObject));
     return stripOpaqueValuesFromPseudoObjectRef(*this, syntax);
   }
 }

lib/Sema/TreeTransform.h

TreeTransform<Derived>::TransformMSPropertyRefExpr(MSPropertyRefExpr *E) {
 
   return new (SemaRef.getASTContext())
       MSPropertyRefExpr(Base.get(), PD, E->isArrow(),
                         SemaRef.getASTContext().PseudoObjectTy, VK_LValue,
                         QualifierLoc, E->getMemberLoc());
 }
 
 template <typename Derived>
+ExprResult TreeTransform<Derived>::TransformMSPropertySubscriptExpr(
+    MSPropertySubscriptExpr *E) {
+  auto BaseRes = getDerived().TransformExpr(E->getBase());
+  if (BaseRes.isInvalid())
+    return ExprError();
+  auto IdxRes = getDerived().TransformExpr(E->getIdx());
+  if (IdxRes.isInvalid())
+    return ExprError();
+
+  if (!getDerived().AlwaysRebuild() &&
+      BaseRes.get() == E->getBase() &&
+      IdxRes.get() == E->getIdx())
+    return E;
+
+  return getDerived().RebuildArraySubscriptExpr(
+      BaseRes.get(), SourceLocation(), IdxRes.get(), E->getRBracketLoc());
+}
+
+template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformSEHTryStmt(SEHTryStmt *S) {
   StmtResult TryBlock = getDerived().TransformCompoundStmt(S->getTryBlock());
   if (TryBlock.isInvalid())
     return StmtError();
 
   StmtResult Handler = getDerived().TransformSEHHandler(S->getHandler());
   if (Handler.isInvalid())
     return StmtError();

lib/Serialization/ASTReaderStmt.cpp

void ASTStmtReader::VisitMSPropertyRefExpr(MSPropertyRefExpr *E) {
   VisitExpr(E);
   E->IsArrow = (Record[Idx++] != 0);
   E->BaseExpr = Reader.ReadSubExpr();
   E->QualifierLoc = Reader.ReadNestedNameSpecifierLoc(F, Record, Idx);
   E->MemberLoc = ReadSourceLocation(Record, Idx);
   E->TheDecl = ReadDeclAs<MSPropertyDecl>(Record, Idx);
 }
 
+void ASTStmtReader::VisitMSPropertySubscriptExpr(MSPropertySubscriptExpr *E) {
+  VisitExpr(E);
+  E->setBase(Reader.ReadSubExpr());
+  E->setIdx(Reader.ReadSubExpr());
+  E->setRBracketLoc(ReadSourceLocation(Record, Idx));
+}
+
 void ASTStmtReader::VisitCXXUuidofExpr(CXXUuidofExpr *E) {
   VisitExpr(E);
   E->setSourceRange(ReadSourceRange(Record, Idx));
   if (E->isTypeOperand()) { // __uuidof(ComType)
     E->setTypeOperandSourceInfo(
         GetTypeSourceInfo(Record, Idx));
     return;
   }
case EXPR_CXX_TYPEID_TYPE:
       S = new (Context) CXXTypeidExpr(Empty, false);
       break;
     case EXPR_CXX_UUIDOF_EXPR:
       S = new (Context) CXXUuidofExpr(Empty, true);
       break;
     case EXPR_CXX_PROPERTY_REF_EXPR:
       S = new (Context) MSPropertyRefExpr(Empty);
       break;
+    case EXPR_CXX_PROPERTY_SUBSCRIPT_EXPR:
+      S = new (Context) MSPropertySubscriptExpr(Empty);
+      break;
     case EXPR_CXX_UUIDOF_TYPE:
       S = new (Context) CXXUuidofExpr(Empty, false);
       break;
     case EXPR_CXX_THIS:
       S = new (Context) CXXThisExpr(Empty);
       break;
     case EXPR_CXX_THROW:
       S = new (Context) CXXThrowExpr(Empty);

lib/Serialization/ASTWriterStmt.cpp

void ASTStmtWriter::VisitMSPropertyRefExpr(MSPropertyRefExpr *E) {
   Record.push_back(E->isArrow());
   Writer.AddStmt(E->getBaseExpr());
   Writer.AddNestedNameSpecifierLoc(E->getQualifierLoc(), Record);
   Writer.AddSourceLocation(E->getMemberLoc(), Record);
   Writer.AddDeclRef(E->getPropertyDecl(), Record);
   Code = serialization::EXPR_CXX_PROPERTY_REF_EXPR;
 }
 
+void ASTStmtWriter::VisitMSPropertySubscriptExpr(MSPropertySubscriptExpr *E) {
+  VisitExpr(E);
+  Writer.AddStmt(E->getBase());
+  Writer.AddStmt(E->getIdx());
+  Writer.AddSourceLocation(E->getRBracketLoc(), Record);
+  Code = serialization::EXPR_CXX_PROPERTY_SUBSCRIPT_EXPR;
+}
+
 void ASTStmtWriter::VisitCXXUuidofExpr(CXXUuidofExpr *E) {
   VisitExpr(E);
   Writer.AddSourceRange(E->getSourceRange(), Record);
   if (E->isTypeOperand()) {
     Writer.AddTypeSourceInfo(E->getTypeOperandSourceInfo(), Record);
     Code = serialization::EXPR_CXX_UUIDOF_TYPE;
   } else {
     Writer.AddStmt(E->getExprOperand());

lib/StaticAnalyzer/Core/ExprEngine.cpp

switch (S->getStmtClass()) {
     // C++ and ARC stuff we don't support yet.
     case Expr::ObjCIndirectCopyRestoreExprClass:
     case Stmt::CXXDependentScopeMemberExprClass:
     case Stmt::CXXTryStmtClass:
     case Stmt::CXXTypeidExprClass:
     case Stmt::CXXUuidofExprClass:
     case Stmt::CXXFoldExprClass:
     case Stmt::MSPropertyRefExprClass:
+    case Stmt::MSPropertySubscriptExprClass:
     case Stmt::CXXUnresolvedConstructExprClass:
     case Stmt::DependentScopeDeclRefExprClass:
     case Stmt::ArrayTypeTraitExprClass:
     case Stmt::ExpressionTraitExprClass:
     case Stmt::UnresolvedLookupExprClass:
     case Stmt::UnresolvedMemberExprClass:
     case Stmt::TypoExprClass:
     case Stmt::CXXNoexceptExprClass:

test/CodeGenCXX/ms-property.cpp

 // RUN: %clang_cc1 -emit-llvm -triple=x86_64-pc-win32 -fms-compatibility %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fms-compatibility -emit-pch -o %t %s
+// RUN: %clang_cc1 -emit-llvm -triple=x86_64-pc-win32 -fms-compatibility -include-pch %t -verify %s -o - | FileCheck %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
 
 class Test1 {
 private:
   int x_;
+  double y_;
 
 public:
   Test1(int x) : x_(x) {}
   __declspec(property(get = get_x)) int X;
   int get_x() const { return x_; }
   static Test1 *GetTest1() { return new Test1(10); }
 };
 
+class S {
+public:
+  __declspec(property(get=GetX,put=PutX)) int x[];
+  int GetX(int i, int j) { return i+j; }
+  void PutX(int i, int j, int k) { j = i = k; }
+};
+
+template <typename T>
+class St {
+public:
+  __declspec(property(get=GetX,put=PutX)) T x[];
+  T GetX(T i, T j) { return i+j; }
+  T GetX() { return 0; }
+  void PutX(T i, T j, T k) { j = i = k; }
+  __declspec(property(get=GetY,put=PutY)) T y[];
+  char GetY(char i,  Test1 j) { return i+j.get_x(); }
+  void PutY(char i, int j, double k) { j = i = k; }
+};
+
+template <typename T>
+void foo(T i, T j) {
+  St<T> bar;
+  Test1 t(i);
+  bar.x[i][j] = bar.x[i][j];
+  bar.y[t.X][j] = bar.x[i][j];
+  bar.x[i][j] = bar.y[bar.x[i][j]][t];
+}
+
+int idx() { return 7; }
+
 // CHECK-LABEL: main
 int main(int argc, char **argv) {
+  Test1 t(argc);
+  S *p1 = 0;
+  St<float> *p2 = 0;
+  // CHECK: call i32 @"\01?GetX@S@@QEAAHHH@Z"(%class.S* %{{.+}}, i32 223, i32 11)
+  int j = p1->x[223][11];
+  // CHECK: [[J:%.+]] = load i32, i32* %
+  // CHECK-NEXT: call void @"\01?PutX@S@@QEAAXHHH@Z"(%class.S* %{{.+}}, i32 23, i32 1, i32 [[J]])
+  p1->x[23][1] = j;
+  // CHECK: call float @"\01?GetX@?$St@M@@QEAAMMM@Z"(%class.St* %{{.+}}, float 2.230000e+02, float 1.100000e+01)
+  float j1 = p2->x[223][11];
+  // CHECK: [[J1:%.+]] = load float, float* %
+  // CHECK-NEXT: call void @"\01?PutX@?$St@M@@QEAAXMMM@Z"(%class.St* %{{.+}}, float 2.300000e+01, float 1.000000e+00, float [[J1]])
+  p2->x[23][1] = j1;
+  // CHECK: [[IDX:%.+]] = call i32 @"\01?idx@@YAHXZ"()
+  // CHECK-NEXT: [[CONV:%.+]] = sitofp i32 [[IDX]] to float
+  // CHECK-NEXT: [[GET:%.+]] = call float @"\01?GetX@?$St@M@@QEAAMMM@Z"(%class.St* %{{.+}}, float [[CONV]], float 1.000000e+00)
+  // CHECK-NEXT: [[INC:%.+]] = fadd float [[GET]], 1.000000e+00
+  // CHECK-NEXT: [[CONV:%.+]] = sitofp i32 [[IDX]] to float
+  // CHECK-NEXT: call void @"\01?PutX@?$St@M@@QEAAXMMM@Z"(%class.St* %{{.+}}, float [[CONV]], float 1.000000e+00, float [[INC]])
+  ++p2->x[idx()][1];
+  // CHECK: call void @"\01??$foo@H@@YAXHH@Z"(i32 %{{.+}}, i32 %{{.+}})
+  foo(argc, (int)argv[0][0]);
+  // CHECK: [[P2:%.+]] = load %class.St*, %class.St** %
+  // CHECK: [[T_X:%.+]] = call i32 @"\01?get_x@Test1@@QEBAHXZ"(%class.Test1* %{{.+}})
+  // CHECK: [[P1:%.+]] = load %class.S*, %class.S** %
+  // CHECK: [[P1_X_22_33:%.+]] = call i32 @"\01?GetX@S@@QEAAHHH@Z"(%class.S* [[P1]], i32 22, i32 33)
+  // CHECK: [[CAST:%.+]] = sitofp i32 [[P1_X_22_33]] to double
+  // CHECK: [[ARGC:%.+]] = load i32, i32* %
+  // CHECK: [[CAST2:%.+]] = trunc i32 [[T_X]] to i8
+  // CHECK: call void @"\01?PutY@?$St@M@@QEAAXDHN@Z"(%class.St* [[P2]], i8 [[CAST2]], i32 [[ARGC]], double [[CAST]])
+  p2->y[t.X][argc] =  p1->x[22][33];
+  // CHECK: [[P2_1:%.+]] = load %class.St*, %class.St**
+  // CHECK: [[P2_2:%.+]] = load %class.St*, %class.St**
+  // CHECK: [[P1:%.+]] = load %class.S*, %class.S**
+  // CHECK: [[ARGC:%.+]] = load i32, i32* %
+  // CHECK: [[P1_X_ARGC_0:%.+]] = call i32 @"\01?GetX@S@@QEAAHHH@Z"(%class.S* [[P1]], i32 [[ARGC]], i32 0)
+  // CHECK: [[CAST:%.+]] = trunc i32 [[P1_X_ARGC_0]] to i8
+  // CHECK: [[P2_Y_p1_X_ARGC_0_T:%.+]] = call i8 @"\01?GetY@?$St@M@@QEAADDVTest1@@@Z"(%class.St* [[P2_2]], i8 [[CAST]], %class.Test1* %{{.+}})
+  // CHECK: [[CAST:%.+]] = sitofp i8 [[P2_Y_p1_X_ARGC_0_T]] to float
+  // CHECK: [[J:%.+]] = load i32, i32* %
+  // CHECK: [[CAST1:%.+]] = sitofp i32 [[J]] to float
+  // CHECK: [[J:%.+]] = load i32, i32* %
+  // CHECK: [[CAST2:%.+]] = sitofp i32 [[J]] to float
+  // CHECK: call void @"\01?PutX@?$St@M@@QEAAXMMM@Z"(%class.St* [[P2_1]], float [[CAST2]], float [[CAST1]], float [[CAST]])
+  p2->x[j][j] = p2->y[p1->x[argc][0]][t];
   // CHECK: [[CALL:%.+]] = call %class.Test1* @"\01?GetTest1@Test1@@SAPEAV1@XZ"()
   // CHECK-NEXT: call i32 @"\01?get_x@Test1@@QEBAHXZ"(%class.Test1* [[CALL]])
   return Test1::GetTest1()->X;
 }
+
+// CHECK: define linkonce_odr void @"\01??$foo@H@@YAXHH@Z"(i32 %{{.+}}, i32 %{{.+}})
+// CHECK: call i32 @"\01?GetX@?$St@H@@QEAAHHH@Z"(%class.St{{.+}}* [[BAR:%.+]], i32 %{{.+}} i32 %{{.+}})
+// CHECK: call void @"\01?PutX@?$St@H@@QEAAXHHH@Z"(%class.St{{.+}}* [[BAR]], i32 %{{.+}}, i32 %{{.+}}, i32 %{{.+}})
+// CHECK: call i32 @"\01?GetX@?$St@H@@QEAAHHH@Z"(%class.St{{.+}}* [[BAR]], i32 %{{.+}} i32 %{{.+}})
+// CHECK: call void @"\01?PutY@?$St@H@@QEAAXDHN@Z"(%class.St{{.+}}* [[BAR]], i8 %{{.+}}, i32 %{{.+}}, double %{{.+}}
+// CHECK: call i32 @"\01?GetX@?$St@H@@QEAAHHH@Z"(%class.St{{.+}}* [[BAR]], i32 %{{.+}} i32 %{{.+}})
+// CHECK: call i8 @"\01?GetY@?$St@H@@QEAADDVTest1@@@Z"(%class.St{{.+}}* [[BAR]], i8 %{{.+}}, %class.Test1* %{{.+}})
+// CHECK: call void @"\01?PutX@?$St@H@@QEAAXHHH@Z"(%class.St{{.+}}* [[BAR]], i32 %{{.+}}, i32 %{{.+}}, i32 %{{.+}})
+#endif //HEADER

test/SemaCXX/ms-property-error.cpp

+// RUN: %clang_cc1 -verify -fms-compatibility %s -fsyntax-only -o -
+
+class S {
+public:
+  __declspec(property(get=GetX,put=PutX)) int x[];
+  int GetX(int i, int j) { return i+j; } // expected-note {{'GetX' declared here}}
+  void PutX(int i, int j, int k) { j = i = k; } // expected-note {{'PutX' declared here}}
+};
+
+template <typename T>
+class St {
+public:
+  __declspec(property(get=GetX,put=PutX)) T x[];
+  T GetX(T i, T j) { return i+j; } // expected-note 3 {{'GetX' declared here}}
+  void PutX(T i, T j, T k) { j = i = k; }  // expected-note 2 {{'PutX' declared here}}
+  ~St() {
+    x[1] = 0; // expected-error {{too few arguments to function call, expected 3, have 2}}
+    x[2][3] = 4;
+    ++x[2][3];
+    x[1][2] = x[3][4][5]; // expected-error {{too many arguments to function call, expected 2, have 3}}
+  }
+};
+
+// CHECK-LABEL: main
+int main(int argc, char **argv) {
+  S *p1 = 0;
+  St<float> *p2 = 0;
+  St<int> a; // expected-note {{in instantiation of member function 'St<int>::~St' requested here}}
+  int j = (p1->x)[223][11][2]; // expected-error {{too many arguments to function call, expected 2, have 3}}
+  (p1->x[23]) = argc; // expected-error {{too few arguments to function call, expected 3, have 2}}
+  float j1 = (p2->x); // expected-error {{too few arguments to function call, expected 2, have 0}}
+  ((p2->x)[23])[1][2] = *argv; // expected-error {{too many arguments to function call, expected 3, have 4}}
+  return ++(((p2->x)[23])); // expected-error {{too few arguments to function call, expected 2, have 1}}
+}

test/SemaCXX/ms-property.cpp

+// RUN: %clang_cc1 -ast-print -verify -triple=x86_64-pc-win32 -fms-compatibility %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fms-compatibility -emit-pch -o %t %s
+// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fms-compatibility -include-pch %t -verify %s -ast-print -o - | FileCheck %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+class Test1 {
+private:
+  int x_;
+
+public:
+  Test1(int x) : x_(x) {}
+  __declspec(property(get = get_x)) int X;
+  int get_x() const { return x_; }
+  static Test1 *GetTest1() { return new Test1(10); }
+};
+
+class S {
+public:
+  __declspec(property(get=GetX,put=PutX)) int x[];
+  int GetX(int i, int j) { return i+j; }
+  void PutX(int i, int j, int k) { j = i = k; }
+};
+
+template <typename T>
+class St {
+public:
+  __declspec(property(get=GetX,put=PutX)) T x[];
+  T GetX(T i, T j) { return i+j; }
+  void PutX(T i, T j, T k) { j = i = k; }
+  ~St() { x[0][0] = x[1][1]; }
+};
+
+// CHECK: this->x[0][0] = this->x[1][1];
+// CHECK: this->x[0][0] = this->x[1][1];
+
+// CHECK-LABEL: main
+int main(int argc, char **argv) {
+  S *p1 = 0;
+  St<float> *p2 = 0;
+  // CHECK: St<int> a;
+  St<int> a;
+  // CHECK-NEXT: int j = (p1->x)[223][11];
+  int j = (p1->x)[223][11];
+  // CHECK-NEXT: (p1->x[23])[1] = j;
+  (p1->x[23])[1] = j;
+  // CHECK-NEXT: float j1 = (p2->x[223][11]);
+  float j1 = (p2->x[223][11]);
+  // CHECK-NEXT: ((p2->x)[23])[1] = j1;
+  ((p2->x)[23])[1] = j1;
+  // CHECK-NEXT: ++(((p2->x)[23])[1]);
+  ++(((p2->x)[23])[1]);
+  // CHECK-NEXT: return Test1::GetTest1()->X;
+  return Test1::GetTest1()->X;
+}
+#endif // HEADER

tools/libclang/CXCursor.cpp

CXCursor cxcursor::MakeCXCursor(const Stmt *S, const Decl *Parent,
   case Stmt::UnaryOperatorClass:
     K = CXCursor_UnaryOperator;
     break;
 
   case Stmt::CXXNoexceptExprClass:
     K = CXCursor_UnaryExpr;
     break;
 
+  case Stmt::MSPropertySubscriptExprClass:
   case Stmt::ArraySubscriptExprClass:
     K = CXCursor_ArraySubscriptExpr;
     break;
 
   case Stmt::OMPArraySectionExprClass:
     K = CXCursor_OMPArraySectionExpr;
     break;