[Temporary] Add an ExprWithCleanups for each C++ MaterializeTemporaryExpr

[timshen]

Summary

These ExprWithCleanups are added for holding a RunCleanupsScope not
for destructor calls; rather, they are for lifetime marks. This requires
ExprWithCleanups to keep a bit to indicate whether it have cleanups with
side effects (e.g. dtor calls).

[rsmith]

include/clang/AST/ExprCXX.h

2871–2872

You may as well put this in the bitfield storage on Stmt.

include/clang/Sema/CleanupInfo.h

32

Should this be |=?

include/clang/Sema/Sema.h

444–445

ExprNeedsCleanups -> ExprWithCleanups

lib/AST/Expr.cpp

2906–2907

You should only return true if IncludePossibleEffects -- cleanupsHaveSideEffects means there might be a side-effect, not that there definitely is one. (This is a pre-existing bug.)

lib/Sema/SemaExpr.cpp

4579

This should inherit the side-effects flag from the ExprWithCleanups in the default argument.

lib/Sema/SemaInit.cpp

6190–6191

Please also sink the calls to mark the destructor referenced and check its access into here too. We should keep the checks for a usable destructor and the triggering of an ExprWithCleanups for the destructor together.

[rsmith]

lib/Sema/SemaExprCXX.cpp

5640–5642

Please pass these flags into ::Create rather than using a setter. Generally, we aim for the AST to be immutable once created.

lib/Sema/SemaInit.cpp

6191

I think this may set ExprNeedsCleanups even when unnecessary, if the MTE is lifetime-extended (I think you only actually want an ExprWithCleanups if the storage duration is SD_Automatic). We can't really deal with that here, because we don't know the storage duration of the MTE yet, but please add a FIXME here to not set ExprNeedsCleanups if the temporary is lifetime-extended.

[timshen]

Update to reflect the comments.

[timshen]

lib/Sema/SemaInit.cpp

6190–6191

Please also sink the calls to mark the destructor referenced and check its access into here too. We should keep the checks for a usable destructor and the triggering of an ExprWithCleanups for the destructor together.

As discussed, MaybeBindToTemporary more or less overlaps with this in the access checking perspective. Added a TODO for a potential merge of MaterializeTemporaryExpr and BindToCXXTemporary in the future.

I think this may set ExprNeedsCleanups even when unnecessary, if the MTE is lifetime-extended (I think you only actually want an ExprWithCleanups if the storage duration is SD_Automatic). We can't really deal with that here, because we don't know the storage duration of the MTE yet, but please add a FIXME here to not set ExprNeedsCleanups if the temporary is lifetime-extended.

Due to the use of pushCleanupAfterFullExpr in CodeGen::EmitMaterializeTemporaryExpr, there has to have a RunCleanupsScope at FullExpr level to delay and forward the cleanups to its upper level. So even for lifetime-extended variables, the cleanup scope is necessary.

[rsmith]

lib/Sema/SemaInit.cpp

6197

Why is this C++-only? We presumably would want to clean up after materialized temporaries in other languages if they ever get created.

6461

Accidentally-deleted?

[timshen]

Removed C++ constrain and added back the missing comment line.

[timshen]

Ping? :)

[rsmith]

LGTM

[timshen]

Clang-tidy is broken by this change. Dependency is added to track the fix.

[timshen]

D21243 is committed. Let's do this again.

[timshen]

Committed as r273312.

include/clang/AST/ExprCXX.h

public:
   /// It's useful to remember the set of blocks;  we could also
   /// remember the set of temporaries, but there's currently
   /// no need.
   typedef BlockDecl *CleanupObject;
 
 private:
   Stmt *SubExpr;
 
   ExprWithCleanups(EmptyShell, unsigned NumObjects);
-  ExprWithCleanups(Expr *SubExpr, ArrayRef<CleanupObject> Objects);
+  ExprWithCleanups(Expr *SubExpr, bool CleanupsHaveSideEffects,
+                   ArrayRef<CleanupObject> Objects);
 
   friend TrailingObjects;
   friend class ASTStmtReader;
 
 public:
   static ExprWithCleanups *Create(const ASTContext &C, EmptyShell empty,
                                   unsigned numObjects);
 
   static ExprWithCleanups *Create(const ASTContext &C, Expr *subexpr,
+                                  bool CleanupsHaveSideEffects,
                                   ArrayRef<CleanupObject> objects);
 
   ArrayRef<CleanupObject> getObjects() const {
     return llvm::makeArrayRef(getTrailingObjects<CleanupObject>(),
                               getNumObjects());
   }
 
   unsigned getNumObjects() const { return ExprWithCleanupsBits.NumObjects; }
 
   CleanupObject getObject(unsigned i) const {
     assert(i < getNumObjects() && "Index out of range");
     return getObjects()[i];
   }
 
   Expr *getSubExpr() { return cast<Expr>(SubExpr); }
   const Expr *getSubExpr() const { return cast<Expr>(SubExpr); }
+  bool cleanupsHaveSideEffects() const {
+    return ExprWithCleanupsBits.CleanupsHaveSideEffects;
+  }
 
   /// As with any mutator of the AST, be very careful
   /// when modifying an existing AST to preserve its invariants.
   void setSubExpr(Expr *E) { SubExpr = E; }
 
   SourceLocation getLocStart() const LLVM_READONLY {
     return SubExpr->getLocStart();
   }

include/clang/AST/Stmt.h

protected:
   };
 
   class ExprWithCleanupsBitfields {
     friend class ExprWithCleanups;
     friend class ASTStmtReader; // deserialization
 
     unsigned : NumExprBits;
 
-    unsigned NumObjects : 32 - NumExprBits;
+    // When false, it must not have side effects.
+    bool CleanupsHaveSideEffects : 1;
+
+    unsigned NumObjects : 32 - 1 - NumExprBits;
   };
 
   class PseudoObjectExprBitfields {
     friend class PseudoObjectExpr;
     friend class ASTStmtReader; // deserialization
 
     unsigned : NumExprBits;
 

include/clang/Sema/CleanupInfo.h

+//===--- CleanupInfo.cpp - Cleanup Control in Sema ------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements a set of operations on whether generating an
+//  ExprWithCleanups in a full expression.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_SEMA_CLEANUP_INFO_H
+#define LLVM_CLANG_SEMA_CLEANUP_INFO_H
+
+namespace clang {
+
+class CleanupInfo {
+  bool ExprNeedsCleanups = false;
+  bool CleanupsHaveSideEffects = false;
+
+public:
+  bool exprNeedsCleanups() const { return ExprNeedsCleanups; }
+
+  bool cleanupsHaveSideEffects() const { return CleanupsHaveSideEffects; }
+
+  void setExprNeedsCleanups(bool SideEffects) {
+    ExprNeedsCleanups = true;
+    CleanupsHaveSideEffects |= SideEffects;
+  }
+
+  void reset() {
+    ExprNeedsCleanups = false;
+    CleanupsHaveSideEffects = false;
+  }
+
+  void mergeFrom(CleanupInfo Rhs) {
+    ExprNeedsCleanups |= Rhs.ExprNeedsCleanups;
+    CleanupsHaveSideEffects |= Rhs.CleanupsHaveSideEffects;
+  }
+};
+
+} // end namespace clang
+
+#endif

include/clang/Sema/ScopeInfo.h

 
 #ifndef LLVM_CLANG_SEMA_SCOPEINFO_H
 #define LLVM_CLANG_SEMA_SCOPEINFO_H
 
 #include "clang/AST/Expr.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/CapturedStmt.h"
 #include "clang/Basic/PartialDiagnostic.h"
+#include "clang/Sema/CleanupInfo.h"
 #include "clang/Sema/Ownership.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include <algorithm>
 
 namespace clang {
 
public:
 
   /// \brief Whether this is a mutable lambda.
   bool Mutable;
 
   /// \brief Whether the (empty) parameter list is explicit.
   bool ExplicitParams;
 
   /// \brief Whether any of the capture expressions requires cleanups.
-  bool ExprNeedsCleanups;
+  CleanupInfo Cleanup;
 
   /// \brief Whether the lambda contains an unexpanded parameter pack.
   bool ContainsUnexpandedParameterPack;
 
   /// \brief If this is a generic lambda, use this as the depth of 
   /// each 'auto' parameter, during initial AST construction.
   unsigned AutoTemplateParameterDepth;
 
public:
   ///  if the enclosing full-expression is instantiation dependent).
   llvm::SmallSet<Expr*, 8> NonODRUsedCapturingExprs; 
 
   SourceLocation PotentialThisCaptureLocation;
 
   LambdaScopeInfo(DiagnosticsEngine &Diag)
     : CapturingScopeInfo(Diag, ImpCap_None), Lambda(nullptr),
       CallOperator(nullptr), NumExplicitCaptures(0), Mutable(false),
-      ExplicitParams(false), ExprNeedsCleanups(false),
+      ExplicitParams(false), Cleanup{},
       ContainsUnexpandedParameterPack(false), AutoTemplateParameterDepth(0),
       GLTemplateParameterList(nullptr) {
     Kind = SK_Lambda;
   }
 
   /// \brief Note when all explicit captures have been added.
   void finishedExplicitCaptures() {
     NumExplicitCaptures = Captures.size();

include/clang/Sema/Sema.h

 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/Module.h"
 #include "clang/Basic/OpenMPKinds.h"
 #include "clang/Basic/PragmaKinds.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TemplateKinds.h"
 #include "clang/Basic/TypeTraits.h"
 #include "clang/Sema/AnalysisBasedWarnings.h"
+#include "clang/Sema/CleanupInfo.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/ExternalSemaSource.h"
 #include "clang/Sema/IdentifierResolver.h"
 #include "clang/Sema/ObjCMethodList.h"
 #include "clang/Sema/Ownership.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/TypoCorrection.h"
public:
   SourceLocation OptimizeOffPragmaLocation;
 
   /// \brief Flag indicating if Sema is building a recovery call expression.
   ///
   /// This flag is used to avoid building recovery call expressions
   /// if Sema is already doing so, which would cause infinite recursions.
   bool IsBuildingRecoveryCallExpr;
 
-  /// ExprNeedsCleanups - True if the current evaluation context
-  /// requires cleanups to be run at its conclusion.
-  bool ExprNeedsCleanups;
+  /// Used to control the generation of ExprWithCleanups.
+  CleanupInfo Cleanup;
 
   /// ExprCleanupObjects - This is the stack of objects requiring
   /// cleanup that are created by the current full expression.  The
   /// element type here is ExprWithCleanups::Object.
   SmallVector<BlockDecl*, 8> ExprCleanupObjects;
 
   /// \brief Store a list of either DeclRefExprs or MemberExprs
   ///  that contain a reference to a variable (constant) that may or may not
public:
 
   /// \brief Data structure used to record current or nested
   /// expression evaluation contexts.
   struct ExpressionEvaluationContextRecord {
     /// \brief The expression evaluation context.
     ExpressionEvaluationContext Context;
 
     /// \brief Whether the enclosing context needed a cleanup.
-    bool ParentNeedsCleanups;
+    CleanupInfo ParentCleanup;
 
     /// \brief Whether we are in a decltype expression.
     bool IsDecltype;
 
     /// \brief The number of active cleanup objects when we entered
     /// this expression evaluation context.
     unsigned NumCleanupObjects;
 
struct ExpressionEvaluationContextRecord {
     SmallVector<CallExpr *, 8> DelayedDecltypeCalls;
 
     /// \brief If we are processing a decltype type, a set of temporary binding
     /// expressions for which we have deferred checking the destructor.
     SmallVector<CXXBindTemporaryExpr *, 8> DelayedDecltypeBinds;
 
     ExpressionEvaluationContextRecord(ExpressionEvaluationContext Context,
                                       unsigned NumCleanupObjects,
-                                      bool ParentNeedsCleanups,
+                                      CleanupInfo ParentCleanup,
                                       Decl *ManglingContextDecl,
                                       bool IsDecltype)
-      : Context(Context), ParentNeedsCleanups(ParentNeedsCleanups),
+      : Context(Context), ParentCleanup(ParentCleanup),
         IsDecltype(IsDecltype), NumCleanupObjects(NumCleanupObjects),
         NumTypos(0),
         ManglingContextDecl(ManglingContextDecl), MangleNumbering() { }
 
     /// \brief Retrieve the mangling numbering context, used to consistently
     /// number constructs like lambdas for mangling.
     MangleNumberingContext &getMangleNumberingContext(ASTContext &Ctx);
 
public:
 
   /// MaybeCreateExprWithCleanups - If the current full-expression
   /// requires any cleanups, surround it with a ExprWithCleanups node.
   /// Otherwise, just returns the passed-in expression.
   Expr *MaybeCreateExprWithCleanups(Expr *SubExpr);
   Stmt *MaybeCreateStmtWithCleanups(Stmt *SubStmt);
   ExprResult MaybeCreateExprWithCleanups(ExprResult SubExpr);
 
+  MaterializeTemporaryExpr *
+  CreateMaterializeTemporaryExpr(QualType T, Expr *Temporary,
+                                 bool BoundToLvalueReference);
+
   ExprResult ActOnFinishFullExpr(Expr *Expr) {
     return ActOnFinishFullExpr(Expr, Expr ? Expr->getExprLoc()
                                           : SourceLocation());
   }
   ExprResult ActOnFinishFullExpr(Expr *Expr, SourceLocation CC,
                                  bool DiscardedValue = false,
                                  bool IsConstexpr = false,
                                  bool IsLambdaInitCaptureInitializer = false);

lib/AST/Expr.cpp

bool Expr::HasSideEffects(const ASTContext &Ctx,
   case MSPropertyRefExprClass:
   case MSPropertySubscriptExprClass:
   case CompoundAssignOperatorClass:
   case VAArgExprClass:
   case AtomicExprClass:
   case CXXThrowExprClass:
   case CXXNewExprClass:
   case CXXDeleteExprClass:
-  case ExprWithCleanupsClass:
   case CoawaitExprClass:
   case CoyieldExprClass:
     // These always have a side-effect.
     return true;
 
   case StmtExprClass: {
     // StmtExprs have a side-effect if any substatement does.
     SideEffectFinder Finder(Ctx, IncludePossibleEffects);
     Finder.Visit(cast<StmtExpr>(this)->getSubStmt());
     return Finder.hasSideEffects();
   }
 
+  case ExprWithCleanupsClass:
+    if (IncludePossibleEffects)
+      if (cast<ExprWithCleanups>(this)->cleanupsHaveSideEffects())
+        return true;
+    break;
+
   case ParenExprClass:
   case ArraySubscriptExprClass:
   case OMPArraySectionExprClass:
   case MemberExprClass:
   case ConditionalOperatorClass:
   case BinaryConditionalOperatorClass:
   case CompoundLiteralExprClass:
   case ExtVectorElementExprClass:

lib/AST/ExprCXX.cpp

CompoundStmt *LambdaExpr::getBody() const {
   return static_cast<CompoundStmt *>(getStoredStmts()[NumCaptures]);
 }
 
 bool LambdaExpr::isMutable() const {
   return !getCallOperator()->isConst();
 }
 
 ExprWithCleanups::ExprWithCleanups(Expr *subexpr,
+                                   bool CleanupsHaveSideEffects,
                                    ArrayRef<CleanupObject> objects)
   : Expr(ExprWithCleanupsClass, subexpr->getType(),
          subexpr->getValueKind(), subexpr->getObjectKind(),
          subexpr->isTypeDependent(), subexpr->isValueDependent(),
          subexpr->isInstantiationDependent(),
          subexpr->containsUnexpandedParameterPack()),
     SubExpr(subexpr) {
+  ExprWithCleanupsBits.CleanupsHaveSideEffects = CleanupsHaveSideEffects;
   ExprWithCleanupsBits.NumObjects = objects.size();
   for (unsigned i = 0, e = objects.size(); i != e; ++i)
     getTrailingObjects<CleanupObject>()[i] = objects[i];
 }
 
 ExprWithCleanups *ExprWithCleanups::Create(const ASTContext &C, Expr *subexpr,
+                                           bool CleanupsHaveSideEffects,
                                            ArrayRef<CleanupObject> objects) {
   void *buffer = C.Allocate(totalSizeToAlloc<CleanupObject>(objects.size()),
                             llvm::alignOf<ExprWithCleanups>());
-  return new (buffer) ExprWithCleanups(subexpr, objects);
+  return new (buffer)
+      ExprWithCleanups(subexpr, CleanupsHaveSideEffects, objects);
 }
 
 ExprWithCleanups::ExprWithCleanups(EmptyShell empty, unsigned numObjects)
   : Expr(ExprWithCleanupsClass, empty) {
   ExprWithCleanupsBits.NumObjects = numObjects;
 }
 
 ExprWithCleanups *ExprWithCleanups::Create(const ASTContext &C,

lib/Analysis/Consumed.cpp

class ConsumedStmtVisitor : public ConstStmtVisitor<ConsumedStmtVisitor> {
   typedef MapType::const_iterator ConstInfoEntry;
   
   AnalysisDeclContext &AC;
   ConsumedAnalyzer &Analyzer;
   ConsumedStateMap *StateMap;
   MapType PropagationMap;
 
   InfoEntry findInfo(const Expr *E) {
+    if (auto Cleanups = dyn_cast<ExprWithCleanups>(E))
+      if (!Cleanups->cleanupsHaveSideEffects())
+        E = Cleanups->getSubExpr();
     return PropagationMap.find(E->IgnoreParens());
   }
   ConstInfoEntry findInfo(const Expr *E) const {
+    if (auto Cleanups = dyn_cast<ExprWithCleanups>(E))
+      if (!Cleanups->cleanupsHaveSideEffects())
+        E = Cleanups->getSubExpr();
     return PropagationMap.find(E->IgnoreParens());
   }
   void insertInfo(const Expr *E, const PropagationInfo &PI) {
     PropagationMap.insert(PairType(E->IgnoreParens(), PI));
   }
 
   void forwardInfo(const Expr *From, const Expr *To);
   void copyInfo(const Expr *From, const Expr *To, ConsumedState CS);

lib/CodeGen/CGExprConstant.cpp

public:
   }
 
   llvm::Constant *VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) {
     // No need for a DefaultInitExprScope: we don't handle 'this' in a
     // constant expression.
     return Visit(DIE->getExpr());
   }
 
+  llvm::Constant *VisitExprWithCleanups(ExprWithCleanups *E) {
+    if (!E->cleanupsHaveSideEffects())
+      return Visit(E->getSubExpr());
+    return nullptr;
+  }
+
   llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E) {
     return Visit(E->GetTemporaryExpr());
   }
 
   llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) {
     if (ILE->isStringLiteralInit())
       return Visit(ILE->getInit(0));
 

lib/Sema/Sema.cpp

: ExternalSource(nullptr),
     MSStructPragmaOn(false),
     MSPointerToMemberRepresentationMethod(
         LangOpts.getMSPointerToMemberRepresentationMethod()),
     VtorDispStack(MSVtorDispAttr::Mode(LangOpts.VtorDispMode)),
     PackStack(0), DataSegStack(nullptr), BSSSegStack(nullptr),
     ConstSegStack(nullptr), CodeSegStack(nullptr), CurInitSeg(nullptr),
     VisContext(nullptr),
     IsBuildingRecoveryCallExpr(false),
-    ExprNeedsCleanups(false), LateTemplateParser(nullptr),
+    Cleanup{}, LateTemplateParser(nullptr),
     LateTemplateParserCleanup(nullptr),
     OpaqueParser(nullptr), IdResolver(pp), StdInitializerList(nullptr),
     CXXTypeInfoDecl(nullptr), MSVCGuidDecl(nullptr),
     NSNumberDecl(nullptr), NSValueDecl(nullptr),
     NSStringDecl(nullptr), StringWithUTF8StringMethod(nullptr),
     ValueWithBytesObjCTypeMethod(nullptr),
     NSArrayDecl(nullptr), ArrayWithObjectsMethod(nullptr),
     NSDictionaryDecl(nullptr), DictionaryWithObjectsMethod(nullptr),
if (getLangOpts().ObjC1)
     NSAPIObj.reset(new NSAPI(Context));
 
   if (getLangOpts().CPlusPlus)
     FieldCollector.reset(new CXXFieldCollector());
 
   // Tell diagnostics how to render things from the AST library.
   Diags.SetArgToStringFn(&FormatASTNodeDiagnosticArgument, &Context);
 
-  ExprEvalContexts.emplace_back(PotentiallyEvaluated, 0, false, nullptr, false);
+  ExprEvalContexts.emplace_back(PotentiallyEvaluated, 0, CleanupInfo{}, nullptr,
+                                false);
 
   FunctionScopes.push_back(new FunctionScopeInfo(Diags));
 
   // Initilization of data sharing attributes stack for OpenMP
   InitDataSharingAttributesStack();
 }
 
 void Sema::addImplicitTypedef(StringRef Name, QualType T) {

lib/Sema/SemaCast.cpp

if (!SrcExpr.get()->isLValue()) {
       Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
         << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
     }
     SrcPointee = SrcType;
   } else {
     // If we're dynamic_casting from a prvalue to an rvalue reference, we need
     // to materialize the prvalue before we bind the reference to it.
     if (SrcExpr.get()->isRValue())
-      SrcExpr = new (Self.Context) MaterializeTemporaryExpr(
-          SrcType, SrcExpr.get(), /*IsLValueReference*/false);
+      SrcExpr = Self.CreateMaterializeTemporaryExpr(
+          SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
     SrcPointee = SrcType;
   }
 
   const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
   if (SrcRecord) {
     if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
                                  diag::err_bad_dynamic_cast_incomplete,
                                  SrcExpr.get())) {
static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
 
   // Since we're dealing in canonical types, the remainder must be the same.
   if (SrcType != DestType)
     return TC_NotApplicable;
 
   if (NeedToMaterializeTemporary)
     // This is a const_cast from a class prvalue to an rvalue reference type.
     // Materialize a temporary to store the result of the conversion.
-    SrcExpr = new (Self.Context) MaterializeTemporaryExpr(
-        SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
+    SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcType, SrcExpr.get(),
+                                                  /*IsLValueReference*/ false);
 
   return TC_Success;
 }
 
 // Checks for undefined behavior in reinterpret_cast.
 // The cases that is checked for is:
 // *reinterpret_cast<T*>(&a)
 // reinterpret_cast<T&>(a)

lib/Sema/SemaCoroutine.cpp

if (E->getType()->isDependentType()) {
     Expr *Res = new (Context) CoawaitExpr(Loc, Context.DependentTy, E);
     Coroutine->CoroutineStmts.push_back(Res);
     return Res;
   }
 
   // If the expression is a temporary, materialize it as an lvalue so that we
   // can use it multiple times.
   if (E->getValueKind() == VK_RValue)
-    E = new (Context) MaterializeTemporaryExpr(E->getType(), E, true);
+    E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
 
   // Build the await_ready, await_suspend, await_resume calls.
   ReadySuspendResumeResult RSS = buildCoawaitCalls(*this, Loc, E);
   if (RSS.IsInvalid)
     return ExprError();
 
   Expr *Res = new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
                                         RSS.Results[2]);
if (E->getType()->isDependentType()) {
     Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
     Coroutine->CoroutineStmts.push_back(Res);
     return Res;
   }
 
   // If the expression is a temporary, materialize it as an lvalue so that we
   // can use it multiple times.
   if (E->getValueKind() == VK_RValue)
-    E = new (Context) MaterializeTemporaryExpr(E->getType(), E, true);
+    E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
 
   // Build the await_ready, await_suspend, await_resume calls.
   ReadySuspendResumeResult RSS = buildCoawaitCalls(*this, Loc, E);
   if (RSS.IsInvalid)
     return ExprError();
 
   Expr *Res = new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
                                         RSS.Results[2]);

lib/Sema/SemaDecl.cpp

if (FD && FD->hasAttr<NakedAttr>()) {
           break;
         }
       }
     }
 
     assert(ExprCleanupObjects.size() ==
                ExprEvalContexts.back().NumCleanupObjects &&
            "Leftover temporaries in function");
-    assert(!ExprNeedsCleanups && "Unaccounted cleanups in function");
+    assert(!Cleanup.exprNeedsCleanups() && "Unaccounted cleanups in function");
     assert(MaybeODRUseExprs.empty() &&
            "Leftover expressions for odr-use checking");
   }
 
   if (!IsInstantiation)
     PopDeclContext();
 
   PopFunctionScopeInfo(ActivePolicy, dcl);

lib/Sema/SemaExpr.cpp

if (T->isMemberPointerType() &&
     (void)isCompleteType(E->getExprLoc(), T);
 
   UpdateMarkingForLValueToRValue(E);
   
   // Loading a __weak object implicitly retains the value, so we need a cleanup to 
   // balance that.
   if (getLangOpts().ObjCAutoRefCount &&
       E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(true);
 
   ExprResult Res = ImplicitCastExpr::Create(Context, T, CK_LValueToRValue, E,
                                             nullptr, VK_RValue);
 
   // C11 6.3.2.1p2:
   //   ... if the lvalue has atomic type, the value has the non-atomic version 
   //   of the type of the lvalue ...
   if (const AtomicType *Atomic = T->getAs<AtomicType>()) {
ExprResult Sema::BuildCXXDefaultArgExpr(SourceLocation CallLoc,
 
   // If the default expression creates temporaries, we need to
   // push them to the current stack of expression temporaries so they'll
   // be properly destroyed.
   // FIXME: We should really be rebuilding the default argument with new
   // bound temporaries; see the comment in PR5810.
   // We don't need to do that with block decls, though, because
   // blocks in default argument expression can never capture anything.
-  if (isa<ExprWithCleanups>(Param->getInit())) {
+  if (auto Init = dyn_cast<ExprWithCleanups>(Param->getInit())) {
     // Set the "needs cleanups" bit regardless of whether there are
     // any explicit objects.
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(Init->cleanupsHaveSideEffects());
 
     // Append all the objects to the cleanup list.  Right now, this
     // should always be a no-op, because blocks in default argument
     // expressions should never be able to capture anything.
-    assert(!cast<ExprWithCleanups>(Param->getInit())->getNumObjects() &&
+    assert(!Init->getNumObjects() &&
            "default argument expression has capturing blocks?");
   }
 
   // We already type-checked the argument, so we know it works. 
   // Just mark all of the declarations in this potentially-evaluated expression
   // as being "referenced".
   MarkDeclarationsReferencedInExpr(Param->getDefaultArg(),
                                    /*SkipLocalVariables=*/true);
void Sema::maybeExtendBlockObject(ExprResult &E) {
   assert(E.get()->isRValue());
 
   // Only do this in an r-value context.
   if (!getLangOpts().ObjCAutoRefCount) return;
 
   E = ImplicitCastExpr::Create(Context, E.get()->getType(),
                                CK_ARCExtendBlockObject, E.get(),
                                /*base path*/ nullptr, VK_RValue);
-  ExprNeedsCleanups = true;
+  Cleanup.setExprNeedsCleanups(true);
 }
 
 /// Prepare a conversion of the given expression to an ObjC object
 /// pointer type.
 CastKind Sema::PrepareCastToObjCObjectPointer(ExprResult &E) {
   QualType type = E.get()->getType();
   if (type->isObjCObjectPointerType()) {
     return CK_BitCast;
QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
   if (lval == Expr::LV_ClassTemporary || lval == Expr::LV_ArrayTemporary) { 
     bool sfinae = (bool)isSFINAEContext();
     Diag(OpLoc, isSFINAEContext() ? diag::err_typecheck_addrof_temporary
                                   : diag::ext_typecheck_addrof_temporary)
       << op->getType() << op->getSourceRange();
     if (sfinae)
       return QualType();
     // Materialize the temporary as an lvalue so that we can take its address.
-    OrigOp = op = new (Context)
-        MaterializeTemporaryExpr(op->getType(), OrigOp.get(), true);
+    OrigOp = op =
+        CreateMaterializeTemporaryExpr(op->getType(), OrigOp.get(), true);
   } else if (isa<ObjCSelectorExpr>(op)) {
     return Context.getPointerType(op->getType());
   } else if (lval == Expr::LV_MemberFunction) {
     // If it's an instance method, make a member pointer.
     // The expression must have exactly the form &A::foo.
 
     // If the underlying expression isn't a decl ref, give up.
     if (!isa<DeclRefExpr>(op)) {

 ExprResult
 Sema::ActOnStmtExpr(SourceLocation LPLoc, Stmt *SubStmt,
                     SourceLocation RPLoc) { // "({..})"
   assert(SubStmt && isa<CompoundStmt>(SubStmt) && "Invalid action invocation!");
   CompoundStmt *Compound = cast<CompoundStmt>(SubStmt);
 
   if (hasAnyUnrecoverableErrorsInThisFunction())
     DiscardCleanupsInEvaluationContext();
-  assert(!ExprNeedsCleanups && "cleanups within StmtExpr not correctly bound!");
+  assert(!Cleanup.exprNeedsCleanups() &&
+         "cleanups within StmtExpr not correctly bound!");
   PopExpressionEvaluationContext();
 
   // 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.
ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
                                     Stmt *Body, Scope *CurScope) {
   // If blocks are disabled, emit an error.
   if (!LangOpts.Blocks)
     Diag(CaretLoc, diag::err_blocks_disable);
 
   // Leave the expression-evaluation context.
   if (hasAnyUnrecoverableErrorsInThisFunction())
     DiscardCleanupsInEvaluationContext();
-  assert(!ExprNeedsCleanups && "cleanups within block not correctly bound!");
+  assert(!Cleanup.exprNeedsCleanups() &&
+         "cleanups within block not correctly bound!");
   PopExpressionEvaluationContext();
 
   BlockScopeInfo *BSI = cast<BlockScopeInfo>(FunctionScopes.back());
 
   if (BSI->HasImplicitReturnType)
     deduceClosureReturnType(*BSI);
 
   PopDeclContext();
ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
   AnalysisBasedWarnings::Policy WP = AnalysisWarnings.getDefaultPolicy();
   PopFunctionScopeInfo(&WP, Result->getBlockDecl(), Result);
 
   // If the block isn't obviously global, i.e. it captures anything at
   // all, then we need to do a few things in the surrounding context:
   if (Result->getBlockDecl()->hasCaptures()) {
     // First, this expression has a new cleanup object.
     ExprCleanupObjects.push_back(Result->getBlockDecl());
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(true);
 
     // It also gets a branch-protected scope if any of the captured
     // variables needs destruction.
     for (const auto &CI : Result->getBlockDecl()->captures()) {
       const VarDecl *var = CI.getVariable();
       if (var->getType().isDestructedType() != QualType::DK_none) {
         getCurFunction()->setHasBranchProtectedScope();
         break;
if (isUnevaluatedContext())
     return E;
   return TransformToPE(*this).TransformExpr(E);
 }
 
 void
 Sema::PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
                                       Decl *LambdaContextDecl,
                                       bool IsDecltype) {
-  ExprEvalContexts.emplace_back(NewContext, ExprCleanupObjects.size(),
-                                ExprNeedsCleanups, LambdaContextDecl,
-                                IsDecltype);
-  ExprNeedsCleanups = false;
+  ExprEvalContexts.emplace_back(NewContext, ExprCleanupObjects.size(), Cleanup,
+                                LambdaContextDecl, IsDecltype);
+  Cleanup.reset();
   if (!MaybeODRUseExprs.empty())
     std::swap(MaybeODRUseExprs, ExprEvalContexts.back().SavedMaybeODRUseExprs);
 }
 
 void
 Sema::PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
                                       ReuseLambdaContextDecl_t,
                                       bool IsDecltype) {
void Sema::PopExpressionEvaluationContext() {
 
   // When are coming out of an unevaluated context, clear out any
   // temporaries that we may have created as part of the evaluation of
   // the expression in that context: they aren't relevant because they
   // will never be constructed.
   if (Rec.isUnevaluated() || Rec.Context == ConstantEvaluated) {
     ExprCleanupObjects.erase(ExprCleanupObjects.begin() + Rec.NumCleanupObjects,
                              ExprCleanupObjects.end());
-    ExprNeedsCleanups = Rec.ParentNeedsCleanups;
+    Cleanup = Rec.ParentCleanup;
     CleanupVarDeclMarking();
     std::swap(MaybeODRUseExprs, Rec.SavedMaybeODRUseExprs);
   // Otherwise, merge the contexts together.
   } else {
-    ExprNeedsCleanups |= Rec.ParentNeedsCleanups;
+    Cleanup.mergeFrom(Rec.ParentCleanup);
     MaybeODRUseExprs.insert(Rec.SavedMaybeODRUseExprs.begin(),
                             Rec.SavedMaybeODRUseExprs.end());
   }
 
   // Pop the current expression evaluation context off the stack.
   ExprEvalContexts.pop_back();
 
   if (!ExprEvalContexts.empty())
     ExprEvalContexts.back().NumTypos += NumTypos;
   else
     assert(NumTypos == 0 && "There are outstanding typos after popping the "
                             "last ExpressionEvaluationContextRecord");
 }
 
 void Sema::DiscardCleanupsInEvaluationContext() {
   ExprCleanupObjects.erase(
          ExprCleanupObjects.begin() + ExprEvalContexts.back().NumCleanupObjects,
          ExprCleanupObjects.end());
-  ExprNeedsCleanups = false;
+  Cleanup.reset();
   MaybeODRUseExprs.clear();
 }
 
 ExprResult Sema::HandleExprEvaluationContextForTypeof(Expr *E) {
   if (!E->getType()->isVariablyModifiedType())
     return E;
   return TransformToPotentiallyEvaluated(E);
 }

lib/Sema/SemaExprCXX.cpp

// cases where we don't have an actual method.
           D && D->getMethodFamily() == OMF_performSelector)
         return E;
     }
 
     // Don't reclaim an object of Class type.
     if (!ReturnsRetained && E->getType()->isObjCARCImplicitlyUnretainedType())
       return E;
 
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(true);
 
     CastKind ck = (ReturnsRetained ? CK_ARCConsumeObject
                                    : CK_ARCReclaimReturnedObject);
     return ImplicitCastExpr::Create(Context, E->getType(), ck, E, nullptr,
                                     VK_RValue);
   }
 
   if (!getLangOpts().CPlusPlus)
if (Destructor) {
     if (DiagnoseUseOfDecl(Destructor, E->getExprLoc()))
       return ExprError();
 
     // If destructor is trivial, we can avoid the extra copy.
     if (Destructor->isTrivial())
       return E;
 
     // We need a cleanup, but we don't need to remember the temporary.
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(true);
   }
 
   CXXTemporary *Temp = CXXTemporary::Create(Context, Destructor);
   CXXBindTemporaryExpr *Bind = CXXBindTemporaryExpr::Create(Context, Temp, E);
 
   if (IsDecltype)
     ExprEvalContexts.back().DelayedDecltypeBinds.push_back(Bind);
 

 
 Expr *Sema::MaybeCreateExprWithCleanups(Expr *SubExpr) {
   assert(SubExpr && "subexpression can't be null!");
 
   CleanupVarDeclMarking();
 
   unsigned FirstCleanup = ExprEvalContexts.back().NumCleanupObjects;
   assert(ExprCleanupObjects.size() >= FirstCleanup);
-  assert(ExprNeedsCleanups || ExprCleanupObjects.size() == FirstCleanup);
-  if (!ExprNeedsCleanups)
+  assert(Cleanup.exprNeedsCleanups() ||
+         ExprCleanupObjects.size() == FirstCleanup);
+  if (!Cleanup.exprNeedsCleanups())
     return SubExpr;
 
   auto Cleanups = llvm::makeArrayRef(ExprCleanupObjects.begin() + FirstCleanup,
                                      ExprCleanupObjects.size() - FirstCleanup);
 
-  Expr *E = ExprWithCleanups::Create(Context, SubExpr, Cleanups);
+  auto *E = ExprWithCleanups::Create(
+      Context, SubExpr, Cleanup.cleanupsHaveSideEffects(), Cleanups);
   DiscardCleanupsInEvaluationContext();
 
   return E;
 }
 
 Stmt *Sema::MaybeCreateStmtWithCleanups(Stmt *SubStmt) {
   assert(SubStmt && "sub-statement can't be null!");
 
   CleanupVarDeclMarking();
 
-  if (!ExprNeedsCleanups)
+  if (!Cleanup.exprNeedsCleanups())
     return SubStmt;
 
   // FIXME: In order to attach the temporaries, wrap the statement into
   // a StmtExpr; currently this is only used for asm statements.
   // This is hacky, either create a new CXXStmtWithTemporaries statement or
   // a new AsmStmtWithTemporaries.
   CompoundStmt *CompStmt = new (Context) CompoundStmt(Context, SubStmt,
                                                       SourceLocation(),
for (unsigned I = 0, N = ExprEvalContexts.back().DelayedDecltypeBinds.size();
     MarkFunctionReferenced(Bind->getExprLoc(), Destructor);
     CheckDestructorAccess(Bind->getExprLoc(), Destructor,
                           PDiag(diag::err_access_dtor_temp)
                             << Bind->getType());
     if (DiagnoseUseOfDecl(Destructor, Bind->getExprLoc()))
       return ExprError();
 
     // We need a cleanup, but we don't need to remember the temporary.
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(true);
   }
 
   // Possibly strip off the top CXXBindTemporaryExpr.
   return E;
 }
 
 /// Note a set of 'operator->' functions that were used for a member access.
 static void noteOperatorArrows(Sema &S,

lib/Sema/SemaExprObjC.cpp

Sema::CheckObjCARCConversion(SourceRange castRange, QualType castType,
   case ACC_plusZero:
     return ACR_okay;
 
   // If the result is +1, consume it here.
   case ACC_plusOne:
     castExpr = ImplicitCastExpr::Create(Context, castExpr->getType(),
                                         CK_ARCConsumeObject, castExpr,
                                         nullptr, VK_RValue);
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(true);
     return ACR_okay;
   }
 
   // If this is a non-implicit cast from id or block type to a
   // CoreFoundation type, delay complaining in case the cast is used
   // in an acceptable context.
   if (exprACTC == ACTC_retainable && isAnyRetainable(castACTC) &&
       CCK != CCK_ImplicitConversion)
if (T->isDependentType() || SubExpr->isTypeDependent()) {
     return ExprError();
   }
 
   Expr *Result = new (Context) ObjCBridgedCastExpr(LParenLoc, Kind, CK,
                                                    BridgeKeywordLoc,
                                                    TSInfo, SubExpr);
   
   if (MustConsume) {
-    ExprNeedsCleanups = true;
+    Cleanup.setExprNeedsCleanups(true);
     Result = ImplicitCastExpr::Create(Context, T, CK_ARCConsumeObject, Result, 
                                       nullptr, VK_RValue);
   }
   
   return Result;
 }
 
 ExprResult Sema::ActOnObjCBridgedCast(Scope *S,

lib/Sema/SemaInit.cpp

 /// indirect copy/restore.
 static void checkIndirectCopyRestoreSource(Sema &S, Expr *src) {
   assert(src->isRValue());
   bool isWeakAccess = false;
   InvalidICRKind iik = isInvalidICRSource(S.Context, src, false, isWeakAccess);
   // If isWeakAccess to true, there will be an implicit 
   // load which requires a cleanup.
   if (S.getLangOpts().ObjCAutoRefCount && isWeakAccess)
-    S.ExprNeedsCleanups = true;
-  
+    S.Cleanup.setExprNeedsCleanups(true);
   if (iik == IIK_okay) return;
 
   S.Diag(src->getExprLoc(), diag::err_arc_nonlocal_writeback)
     << ((unsigned) iik - 1)  // shift index into diagnostic explanations
     << src->getSourceRange();
 }
 
 /// \brief Determine whether we have compatible array types for the
if (UO->getOpcode() == UO_Deref &&
         UO->getSubExpr()->IgnoreParenCasts()->
         isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)) {
     S.DiagRuntimeBehavior(UO->getOperatorLoc(), UO,
                           S.PDiag(diag::warn_binding_null_to_reference)
                             << UO->getSubExpr()->getSourceRange());
   }
 }
 
+MaterializeTemporaryExpr *
+Sema::CreateMaterializeTemporaryExpr(QualType T, Expr *Temporary,
+                                     bool BoundToLvalueReference) {
+  auto MTE = new (Context)
+      MaterializeTemporaryExpr(T, Temporary, BoundToLvalueReference);
+
+  // Order an ExprWithCleanups for lifetime marks.
+  //
+  // TODO: It'll be good to have a single place to check the access of the
+  // destructor and generate ExprWithCleanups for various uses. Currently these
+  // are done in both CreateMaterializeTemporaryExpr and MaybeBindToTemporary,
+  // but there may be a chance to merge them.
+  if (getLangOpts().CPlusPlus)
+    Cleanup.setExprNeedsCleanups(false);
+  return MTE;
+}
+
 ExprResult
 InitializationSequence::Perform(Sema &S,
                                 const InitializedEntity &Entity,
                                 const InitializationKind &Kind,
                                 MultiExprArg Args,
                                 QualType *ResultType) {
   if (Failed()) {
     Diagnose(S, Entity, Kind, Args);
case SK_BindReferenceToTemporary: {
       // Make sure the "temporary" is actually an rvalue.
       assert(CurInit.get()->isRValue() && "not a temporary");
 
       // Check exception specifications
       if (S.CheckExceptionSpecCompatibility(CurInit.get(), DestType))
         return ExprError();
 
       // Materialize the temporary into memory.
-      MaterializeTemporaryExpr *MTE = new (S.Context) MaterializeTemporaryExpr(
+      MaterializeTemporaryExpr *MTE = S.CreateMaterializeTemporaryExpr(
           Entity.getType().getNonReferenceType(), CurInit.get(),
           Entity.getType()->isLValueReferenceType());
 
       // Maybe lifetime-extend the temporary's subobjects to match the
       // entity's lifetime.
       if (const InitializedEntity *ExtendingEntity =
               getEntityForTemporaryLifetimeExtension(&Entity))
         if (performReferenceExtension(MTE, ExtendingEntity))
           warnOnLifetimeExtension(S, Entity, CurInit.get(), /*IsInitializerList=*/false,
                                   ExtendingEntity->getDecl());
 
-      // If we're binding to an Objective-C object that has lifetime, we
       // need cleanups. Likewise if we're extending this temporary to automatic
       // storage duration -- we need to register its cleanup during the
       // full-expression's cleanups.
       if ((S.getLangOpts().ObjCAutoRefCount &&
            MTE->getType()->isObjCLifetimeType()) ||
           (MTE->getStorageDuration() == SD_Automatic &&
            MTE->getType().isDestructedType()))
-        S.ExprNeedsCleanups = true;
+        S.Cleanup.setExprNeedsCleanups(true);
 
       CurInit = MTE;
       break;
     }
 
     case SK_ExtraneousCopyToTemporary:
       CurInit = CopyObject(S, Step->Type, Entity, CurInit,
                            /*IsExtraneousCopy=*/true);
case SK_ProduceObjCObject:
       break;
 
     case SK_StdInitializerList: {
       S.Diag(CurInit.get()->getExprLoc(),
              diag::warn_cxx98_compat_initializer_list_init)
         << CurInit.get()->getSourceRange();
 
       // Materialize the temporary into memory.
-      MaterializeTemporaryExpr *MTE = new (S.Context)
-          MaterializeTemporaryExpr(CurInit.get()->getType(), CurInit.get(),
-                                   /*BoundToLvalueReference=*/false);
+      MaterializeTemporaryExpr *MTE = S.CreateMaterializeTemporaryExpr(
+          CurInit.get()->getType(), CurInit.get(),
 
       // Maybe lifetime-extend the array temporary's subobjects to match the
       // entity's lifetime.
       if (const InitializedEntity *ExtendingEntity =
               getEntityForTemporaryLifetimeExtension(&Entity))
         if (performReferenceExtension(MTE, ExtendingEntity))
           warnOnLifetimeExtension(S, Entity, CurInit.get(),
                                   /*IsInitializerList=*/true,

lib/Sema/SemaLambda.cpp

ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
   SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
   LambdaCaptureDefault CaptureDefault =
       mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
   CXXRecordDecl *Class;
   CXXMethodDecl *CallOperator;
   SourceRange IntroducerRange;
   bool ExplicitParams;
   bool ExplicitResultType;
-  bool LambdaExprNeedsCleanups;
+  CleanupInfo LambdaCleanup;
   bool ContainsUnexpandedParameterPack;
   SmallVector<VarDecl *, 4> ArrayIndexVars;
   SmallVector<unsigned, 4> ArrayIndexStarts;
   {
     CallOperator = LSI->CallOperator;
     Class = LSI->Lambda;
     IntroducerRange = LSI->IntroducerRange;
     ExplicitParams = LSI->ExplicitParams;
     ExplicitResultType = !LSI->HasImplicitReturnType;
-    LambdaExprNeedsCleanups = LSI->ExprNeedsCleanups;
+    LambdaCleanup = LSI->Cleanup;
     ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
     
     CallOperator->setLexicalDeclContext(Class);
     Decl *TemplateOrNonTemplateCallOperatorDecl = 
         CallOperator->getDescribedFunctionTemplate()  
         ? CallOperator->getDescribedFunctionTemplate() 
         : cast<Decl>(CallOperator);
 
SmallVector<unsigned, 4> ArrayIndexStarts;
     
     // Finalize the lambda class.
     SmallVector<Decl*, 4> Fields(Class->fields());
     ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
                 SourceLocation(), nullptr);
     CheckCompletedCXXClass(Class);
   }
 
-  if (LambdaExprNeedsCleanups)
-    ExprNeedsCleanups = true;
-  
+  Cleanup.mergeFrom(LambdaCleanup);
   LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange, 
                                           CaptureDefault, CaptureDefaultLoc,
                                           Captures, 
                                           ExplicitParams, ExplicitResultType,
                                           CaptureInits, ArrayIndexVars, 
                                           ArrayIndexStarts, EndLoc,
                                           ContainsUnexpandedParameterPack);
   // If the lambda expression's call operator is not explicitly marked constexpr
ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
 
   // Add a fake function body to the block. IR generation is responsible
   // for filling in the actual body, which cannot be expressed as an AST.
   Block->setBody(new (Context) CompoundStmt(ConvLocation));
 
   // Create the block literal expression.
   Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
   ExprCleanupObjects.push_back(Block);
-  ExprNeedsCleanups = true;
+  Cleanup.setExprNeedsCleanups(true);
 
   return BuildBlock;
 }

lib/Sema/SemaOpenMP.cpp

bool OpenMPIterationSpaceChecker::CheckInit(Stmt *S, bool EmitDiags) {
   //   pointer-type var = lb
   //
   if (!S) {
     if (EmitDiags) {
       SemaRef.Diag(DefaultLoc, diag::err_omp_loop_not_canonical_init);
     }
     return true;
   }
+  if (auto *ExprTemp = dyn_cast<ExprWithCleanups>(S))
+    if (!ExprTemp->cleanupsHaveSideEffects())
+      S = ExprTemp->getSubExpr();
+
   InitSrcRange = S->getSourceRange();
   if (Expr *E = dyn_cast<Expr>(S))
     S = E->IgnoreParens();
   if (auto BO = dyn_cast<BinaryOperator>(S)) {
     if (BO->getOpcode() == BO_Assign) {
       auto *LHS = BO->getLHS()->IgnoreParens();
       if (auto *DRE = dyn_cast<DeclRefExpr>(LHS)) {
         if (auto *CED = dyn_cast<OMPCapturedExprDecl>(DRE->getDecl()))
bool OpenMPIterationSpaceChecker::CheckInc(Expr *S) {
   //   var = var + incr
   //   var = incr + var
   //   var = var - incr
   //
   if (!S) {
     SemaRef.Diag(DefaultLoc, diag::err_omp_loop_not_canonical_incr) << LCDecl;
     return true;
   }
+  if (auto *ExprTemp = dyn_cast<ExprWithCleanups>(S))
+    if (!ExprTemp->cleanupsHaveSideEffects())
+      S = ExprTemp->getSubExpr();
+
   IncrementSrcRange = S->getSourceRange();
   S = S->IgnoreParens();
   if (auto UO = dyn_cast<UnaryOperator>(S)) {
     if (UO->isIncrementDecrementOp() &&
         GetInitLCDecl(UO->getSubExpr()) == LCDecl)
       return SetStep(
           SemaRef.ActOnIntegerConstant(UO->getLocStart(),
                                        (UO->isDecrementOp() ? -1 : 1)).get(),

lib/Sema/SemaStmt.cpp

void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
 
     S.Diag(Ranges.begin()->getBegin(), PDiag);
   }
 
   // If Statement is an incemement or decrement, return true and sets the
   // variables Increment and DRE.
   bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment,
                             DeclRefExpr *&DRE) {
+    if (auto Cleanups = dyn_cast<ExprWithCleanups>(Statement))
+      if (!Cleanups->cleanupsHaveSideEffects())
+        Statement = Cleanups->getSubExpr();
+
     if (UnaryOperator *UO = dyn_cast<UnaryOperator>(Statement)) {
       switch (UO->getOpcode()) {
         default: return false;
         case UO_PostInc:
         case UO_PreInc:
           Increment = true;
           break;
         case UO_PostDec:
static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef,
                                                     const VarDecl *VD,
                                                     QualType RangeInitType) {
   const Expr *InitExpr = VD->getInit();
   if (!InitExpr)
     return;
 
   QualType VariableType = VD->getType();
 
+  if (auto Cleanups = dyn_cast<ExprWithCleanups>(InitExpr))
+    if (!Cleanups->cleanupsHaveSideEffects())
+      InitExpr = Cleanups->getSubExpr();
+
   const MaterializeTemporaryExpr *MTE =
       dyn_cast<MaterializeTemporaryExpr>(InitExpr);
 
   // No copy made.
   if (!MTE)
     return;
 
   const Expr *E = MTE->GetTemporaryExpr()->IgnoreImpCasts();

lib/Serialization/ASTReaderStmt.cpp

void ASTStmtReader::VisitExprWithCleanups(ExprWithCleanups *E) {
   VisitExpr(E);
 
   unsigned NumObjects = Record[Idx++];
   assert(NumObjects == E->getNumObjects());
   for (unsigned i = 0; i != NumObjects; ++i)
     E->getTrailingObjects<BlockDecl *>()[i] =
         ReadDeclAs<BlockDecl>(Record, Idx);
 
+  E->ExprWithCleanupsBits.CleanupsHaveSideEffects = Record[Idx++];
   E->SubExpr = Reader.ReadSubExpr();
 }
 
 void
 ASTStmtReader::VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E){
   VisitExpr(E);
 
   if (Record[Idx++]) // HasTemplateKWAndArgsInfo

lib/Serialization/ASTWriterStmt.cpp

void ASTStmtWriter::VisitCXXPseudoDestructorExpr(CXXPseudoDestructorExpr *E) {
   Code = serialization::EXPR_CXX_PSEUDO_DESTRUCTOR;
 }
 
 void ASTStmtWriter::VisitExprWithCleanups(ExprWithCleanups *E) {
   VisitExpr(E);
   Record.push_back(E->getNumObjects());
   for (unsigned i = 0, e = E->getNumObjects(); i != e; ++i)
     Record.AddDeclRef(E->getObject(i));
-  
+  Record.push_back(E->cleanupsHaveSideEffects());
   Record.AddStmt(E->getSubExpr());
   Code = serialization::EXPR_EXPR_WITH_CLEANUPS;
 }
 
 void
 ASTStmtWriter::VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E){
   VisitExpr(E);
 

unittests/ASTMatchers/ASTMatchersNodeTest.cpp

 TEST(DeclarationStatement, MatchesVariableDeclarationStatements) {
   EXPECT_TRUE(matches("void x() { int a; }", declStmt()));
 }
 
 TEST(ExprWithCleanups, MatchesExprWithCleanups) {
   EXPECT_TRUE(matches("struct Foo { ~Foo(); };"
                         "const Foo f = Foo();",
                       varDecl(hasInitializer(exprWithCleanups()))));
-  EXPECT_FALSE(matches("struct Foo { };"
-                         "const Foo f = Foo();",
+  EXPECT_FALSE(matches("struct Foo { }; Foo a;"
+                       "const Foo f = a;",
                        varDecl(hasInitializer(exprWithCleanups()))));
 }
 
 TEST(InitListExpression, MatchesInitListExpression) {
   EXPECT_TRUE(matches("int a[] = { 1, 2 };",
                       initListExpr(hasType(asString("int [2]")))));
   EXPECT_TRUE(matches("struct B { int x, y; }; B b = { 5, 6 };",
                       initListExpr(hasType(recordDecl(hasName("B"))))));