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//===- ScopeInfo.h - Information about a semantic context -------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file defines FunctionScopeInfo and its subclasses, which contain

// information about a single function, block, lambda, or method body.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_SEMA_SCOPEINFO_H

#define LLVM_CLANG_SEMA_SCOPEINFO_H

#include "clang/AST/Expr.h"

#include "clang/AST/ExprCXX.h"

#include "clang/AST/Type.h"

#include "clang/Basic/CapturedStmt.h"

#include "clang/Basic/LLVM.h"

#include "clang/Basic/PartialDiagnostic.h"

#include "clang/Basic/SourceLocation.h"

#include "clang/Sema/CleanupInfo.h"

#include "clang/Sema/DeclSpec.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/DenseMapInfo.h"

#include "llvm/ADT/MapVector.h"

#include "llvm/ADT/PointerIntPair.h"

#include "llvm/ADT/SmallPtrSet.h"

#include "llvm/ADT/SmallSet.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/ADT/StringSwitch.h"

#include "llvm/ADT/TinyPtrVector.h"

#include "llvm/Support/Casting.h"

#include "llvm/Support/ErrorHandling.h"

#include <algorithm>

#include <cassert>

#include <utility>

namespace clang {

class BlockDecl;

class CapturedDecl;

class CXXMethodDecl;

class CXXRecordDecl;

class ImplicitParamDecl;

class NamedDecl;

class ObjCIvarRefExpr;

class ObjCMessageExpr;

class ObjCPropertyDecl;

class ObjCPropertyRefExpr;

class ParmVarDecl;

class RecordDecl;

class ReturnStmt;

class Scope;

class Stmt;

class SwitchStmt;

class TemplateParameterList;

class VarDecl;

namespace sema {

/// Contains information about the compound statement currently being

/// parsed.

class CompoundScopeInfo {

public:

  /// Whether this compound stamement contains `for' or `while' loops

  /// with empty bodies.

  bool HasEmptyLoopBodies = false;

  /// Whether this compound statement corresponds to a GNU statement

  /// expression.

  bool IsStmtExpr;

  /// FP options at the beginning of the compound statement, prior to

  /// any pragma.

  FPOptions InitialFPFeatures;

  CompoundScopeInfo(bool IsStmtExpr, FPOptions FPO)

      : IsStmtExpr(IsStmtExpr), InitialFPFeatures(FPO) {}

  void setHasEmptyLoopBodies() {

    HasEmptyLoopBodies = true;

  }

};

class PossiblyUnreachableDiag {

public:

  PartialDiagnostic PD;

  SourceLocation Loc;

  llvm::TinyPtrVector<const Stmt*> Stmts;

  PossiblyUnreachableDiag(const PartialDiagnostic &PD, SourceLocation Loc,

                          ArrayRef<const Stmt *> Stmts)

      : PD(PD), Loc(Loc), Stmts(Stmts) {}

};

/// Retains information about a function, method, or block that is

/// currently being parsed.

class FunctionScopeInfo {

protected:

  enum ScopeKind {

    SK_Function,

    SK_Block,

    SK_Lambda,

    SK_CapturedRegion

  };

public:

  /// What kind of scope we are describing.

  ScopeKind Kind : 3;

  /// Whether this function contains a VLA, \@try, try, C++

  /// initializer, or anything else that can't be jumped past.

  bool HasBranchProtectedScope : 1;

  /// Whether this function contains any switches or direct gotos.

  bool HasBranchIntoScope : 1;

  /// Whether this function contains any indirect gotos.

  bool HasIndirectGoto : 1;

  /// Whether this function contains any statement marked with

  /// \c [[clang::musttail]].

  bool HasMustTail : 1;

  /// Whether a statement was dropped because it was invalid.

  bool HasDroppedStmt : 1;

  /// True if current scope is for OpenMP declare reduction combiner.

  bool HasOMPDeclareReductionCombiner : 1;

  /// Whether there is a fallthrough statement in this function.

  bool HasFallthroughStmt : 1;

  /// Whether this function uses constrained floating point intrinsics

  bool UsesFPIntrin : 1;

  /// Whether we make reference to a declaration that could be

  /// unavailable.

  bool HasPotentialAvailabilityViolations : 1;

  /// A flag that is set when parsing a method that must call super's

  /// implementation, such as \c -dealloc, \c -finalize, or any method marked

  /// with \c __attribute__((objc_requires_super)).

  bool ObjCShouldCallSuper : 1;

  /// True when this is a method marked as a designated initializer.

  bool ObjCIsDesignatedInit : 1;

  /// This starts true for a method marked as designated initializer and will

  /// be set to false if there is an invocation to a designated initializer of

  /// the super class.

  bool ObjCWarnForNoDesignatedInitChain : 1;

  /// True when this is an initializer method not marked as a designated

  /// initializer within a class that has at least one initializer marked as a

  /// designated initializer.

  bool ObjCIsSecondaryInit : 1;

  /// This starts true for a secondary initializer method and will be set to

  /// false if there is an invocation of an initializer on 'self'.

  bool ObjCWarnForNoInitDelegation : 1;

  /// True only when this function has not already built, or attempted

  /// to build, the initial and final coroutine suspend points

  bool NeedsCoroutineSuspends : 1;

  /// An enumeration represeting the kind of the first coroutine statement

  /// in the function. One of co_return, co_await, or co_yield.

  unsigned char FirstCoroutineStmtKind : 2;

  /// First coroutine statement in the current function.

  /// (ex co_return, co_await, co_yield)

  SourceLocation FirstCoroutineStmtLoc;

  /// First 'return' statement in the current function.

  SourceLocation FirstReturnLoc;

  /// First C++ 'try' or ObjC @try statement in the current function.

  SourceLocation FirstCXXOrObjCTryLoc;

  enum { TryLocIsCXX, TryLocIsObjC, Unknown } FirstTryType = Unknown;

  /// First SEH '__try' statement in the current function.

  SourceLocation FirstSEHTryLoc;

private:

  /// Used to determine if errors occurred in this function or block.

  DiagnosticErrorTrap ErrorTrap;

public:

  /// A SwitchStmt, along with a flag indicating if its list of case statements

  /// is incomplete (because we dropped an invalid one while parsing).

  using SwitchInfo = llvm::PointerIntPair<SwitchStmt*, 1, bool>;

  /// SwitchStack - This is the current set of active switch statements in the

  /// block.

  SmallVector<SwitchInfo, 8> SwitchStack;

  /// The list of return statements that occur within the function or

  /// block, if there is any chance of applying the named return value

  /// optimization, or if we need to infer a return type.

  SmallVector<ReturnStmt*, 4> Returns;

  /// The promise object for this coroutine, if any.

  VarDecl *CoroutinePromise = nullptr;

  /// A mapping between the coroutine function parameters that were moved

  /// to the coroutine frame, and their move statements.

  llvm::SmallMapVector<ParmVarDecl *, Stmt *, 4> CoroutineParameterMoves;

  /// The initial and final coroutine suspend points.

  std::pair<Stmt *, Stmt *> CoroutineSuspends;

  /// The stack of currently active compound stamement scopes in the

  /// function.

  SmallVector<CompoundScopeInfo, 4> CompoundScopes;

  /// The set of blocks that are introduced in this function.

  llvm::SmallPtrSet<const BlockDecl *, 1> Blocks;

  /// The set of __block variables that are introduced in this function.

  llvm::TinyPtrVector<VarDecl *> ByrefBlockVars;

  /// A list of PartialDiagnostics created but delayed within the

  /// current function scope.  These diagnostics are vetted for reachability

  /// prior to being emitted.

  SmallVector<PossiblyUnreachableDiag, 4> PossiblyUnreachableDiags;

  /// A list of parameters which have the nonnull attribute and are

  /// modified in the function.

  llvm::SmallPtrSet<const ParmVarDecl *, 8> ModifiedNonNullParams;

  /// The set of GNU address of label extension "&&label".

  llvm::SmallVector<AddrLabelExpr *, 4> AddrLabels;

public:

  /// Represents a simple identification of a weak object.

  ///

  /// Part of the implementation of -Wrepeated-use-of-weak.

  ///

  /// This is used to determine if two weak accesses refer to the same object.

  /// Here are some examples of how various accesses are "profiled":

  ///

  /// Access Expression |     "Base" Decl     |          "Property" Decl

  /// :---------------: | :-----------------: | :------------------------------:

  /// self.property     | self (VarDecl)      | property (ObjCPropertyDecl)

  /// self.implicitProp | self (VarDecl)      | -implicitProp (ObjCMethodDecl)

  /// self->ivar.prop   | ivar (ObjCIvarDecl) | prop (ObjCPropertyDecl)

  /// cxxObj.obj.prop   | obj (FieldDecl)     | prop (ObjCPropertyDecl)

  /// [self foo].prop   | 0 (unknown)         | prop (ObjCPropertyDecl)

  /// self.prop1.prop2  | prop1 (ObjCPropertyDecl)    | prop2 (ObjCPropertyDecl)

  /// MyClass.prop      | MyClass (ObjCInterfaceDecl) | -prop (ObjCMethodDecl)

  /// MyClass.foo.prop  | +foo (ObjCMethodDecl)       | -prop (ObjCPropertyDecl)

  /// weakVar           | 0 (known)           | weakVar (VarDecl)

  /// self->weakIvar    | self (VarDecl)      | weakIvar (ObjCIvarDecl)

  ///

  /// Objects are identified with only two Decls to make it reasonably fast to

  /// compare them.

  class WeakObjectProfileTy {

    /// The base object decl, as described in the class documentation.

    ///

    /// The extra flag is "true" if the Base and Property are enough to uniquely

    /// identify the object in memory.

    ///

    /// \sa isExactProfile()

    using BaseInfoTy = llvm::PointerIntPair<const NamedDecl *, 1, bool>;

    BaseInfoTy Base;

    /// The "property" decl, as described in the class documentation.

    ///

    /// Note that this may not actually be an ObjCPropertyDecl, e.g. in the

    /// case of "implicit" properties (regular methods accessed via dot syntax).

    const NamedDecl *Property = nullptr;

    /// Used to find the proper base profile for a given base expression.

    static BaseInfoTy getBaseInfo(const Expr *BaseE);

    inline WeakObjectProfileTy();

    static inline WeakObjectProfileTy getSentinel();

  public:

    WeakObjectProfileTy(const ObjCPropertyRefExpr *RE);

    WeakObjectProfileTy(const Expr *Base, const ObjCPropertyDecl *Property);

    WeakObjectProfileTy(const DeclRefExpr *RE);

    WeakObjectProfileTy(const ObjCIvarRefExpr *RE);

    const NamedDecl *getBase() const { return Base.getPointer(); }

    const NamedDecl *getProperty() const { return Property; }

    /// Returns true if the object base specifies a known object in memory,

    /// rather than, say, an instance variable or property of another object.

    ///

    /// Note that this ignores the effects of aliasing; that is, \c foo.bar is

    /// considered an exact profile if \c foo is a local variable, even if

    /// another variable \c foo2 refers to the same object as \c foo.

    ///

    /// For increased precision, accesses with base variables that are

    /// properties or ivars of 'self' (e.g. self.prop1.prop2) are considered to

    /// be exact, though this is not true for arbitrary variables

    /// (foo.prop1.prop2).

    bool isExactProfile() const {

      return Base.getInt();

    }

    bool operator==(const WeakObjectProfileTy &Other) const {

      return Base == Other.Base && Property == Other.Property;

    }

    // For use in DenseMap.

    // We can't specialize the usual llvm::DenseMapInfo at the end of the file

    // because by that point the DenseMap in FunctionScopeInfo has already been

    // instantiated.

    class DenseMapInfo {

    public:

      static inline WeakObjectProfileTy getEmptyKey() {

        return WeakObjectProfileTy();

      }

      static inline WeakObjectProfileTy getTombstoneKey() {

        return WeakObjectProfileTy::getSentinel();

      }

      static unsigned getHashValue(const WeakObjectProfileTy &Val) {

        using Pair = std::pair<BaseInfoTy, const NamedDecl *>;

        return llvm::DenseMapInfo<Pair>::getHashValue(Pair(Val.Base,

                                                           Val.Property));

      }

      static bool isEqual(const WeakObjectProfileTy &LHS,

                          const WeakObjectProfileTy &RHS) {

        return LHS == RHS;

      }

    };

  };

  /// Represents a single use of a weak object.

  ///

  /// Stores both the expression and whether the access is potentially unsafe

  /// (i.e. it could potentially be warned about).

  ///

  /// Part of the implementation of -Wrepeated-use-of-weak.

  class WeakUseTy {

    llvm::PointerIntPair<const Expr *, 1, bool> Rep;

  public:

    WeakUseTy(const Expr *Use, bool IsRead) : Rep(Use, IsRead) {}

    const Expr *getUseExpr() const { return Rep.getPointer(); }

    bool isUnsafe() const { return Rep.getInt(); }

    void markSafe() { Rep.setInt(false); }

    bool operator==(const WeakUseTy &Other) const {

      return Rep == Other.Rep;

    }

  };

  /// Used to collect uses of a particular weak object in a function body.

  ///

  /// Part of the implementation of -Wrepeated-use-of-weak.

  using WeakUseVector = SmallVector<WeakUseTy, 4>;

  /// Used to collect all uses of weak objects in a function body.

  ///

  /// Part of the implementation of -Wrepeated-use-of-weak.

  using WeakObjectUseMap =

      llvm::SmallDenseMap<WeakObjectProfileTy, WeakUseVector, 8,

                          WeakObjectProfileTy::DenseMapInfo>;

private:

  /// Used to collect all uses of weak objects in this function body.

  ///

  /// Part of the implementation of -Wrepeated-use-of-weak.

  WeakObjectUseMap WeakObjectUses;

protected:

  FunctionScopeInfo(const FunctionScopeInfo&) = default;

public:

  FunctionScopeInfo(DiagnosticsEngine &Diag)

      : Kind(SK_Function), HasBranchProtectedScope(false),

        HasBranchIntoScope(false), HasIndirectGoto(false), HasMustTail(false),

        HasDroppedStmt(false), HasOMPDeclareReductionCombiner(false),

        HasFallthroughStmt(false), UsesFPIntrin(false),

        HasPotentialAvailabilityViolations(false), ObjCShouldCallSuper(false),

        ObjCIsDesignatedInit(false), ObjCWarnForNoDesignatedInitChain(false),

        ObjCIsSecondaryInit(false), ObjCWarnForNoInitDelegation(false),

        NeedsCoroutineSuspends(true), ErrorTrap(Diag) {}

  virtual ~FunctionScopeInfo();

  /// Determine whether an unrecoverable error has occurred within this

  /// function. Note that this may return false even if the function body is

  /// invalid, because the errors may be suppressed if they're caused by prior

  /// invalid declarations.

  ///

  /// FIXME: Migrate the caller of this to use containsErrors() instead once

  /// it's ready.

  bool hasUnrecoverableErrorOccurred() const {

    return ErrorTrap.hasUnrecoverableErrorOccurred();

  }

  /// Record that a weak object was accessed.

  ///

  /// Part of the implementation of -Wrepeated-use-of-weak.

  template <typename ExprT>

  inline void recordUseOfWeak(const ExprT *E, bool IsRead = true);

  void recordUseOfWeak(const ObjCMessageExpr *Msg,

                       const ObjCPropertyDecl *Prop);

  /// Record that a given expression is a "safe" access of a weak object (e.g.

  /// assigning it to a strong variable.)

  ///

  /// Part of the implementation of -Wrepeated-use-of-weak.

  void markSafeWeakUse(const Expr *E);

  const WeakObjectUseMap &getWeakObjectUses() const {

    return WeakObjectUses;

  }

  void setHasBranchIntoScope() {

    HasBranchIntoScope = true;

  }

  void setHasBranchProtectedScope() {

    HasBranchProtectedScope = true;

  }

  void setHasIndirectGoto() {

    HasIndirectGoto = true;

  }

  void setHasMustTail() { HasMustTail = true; }

  void setHasDroppedStmt() {

    HasDroppedStmt = true;

  }

  void setHasOMPDeclareReductionCombiner() {

    HasOMPDeclareReductionCombiner = true;

  }

  void setHasFallthroughStmt() {

    HasFallthroughStmt = true;

  }

  void setUsesFPIntrin() {

    UsesFPIntrin = true;

  }

  void setHasCXXTry(SourceLocation TryLoc) {

    setHasBranchProtectedScope();

    FirstCXXOrObjCTryLoc = TryLoc;

    FirstTryType = TryLocIsCXX;

  }

  void setHasObjCTry(SourceLocation TryLoc) {

    setHasBranchProtectedScope();

    FirstCXXOrObjCTryLoc = TryLoc;

    FirstTryType = TryLocIsObjC;

  }

  void setHasSEHTry(SourceLocation TryLoc) {

    setHasBranchProtectedScope();

    FirstSEHTryLoc = TryLoc;

  }

  bool NeedsScopeChecking() const {

    return !HasDroppedStmt && (HasIndirectGoto || HasMustTail ||

                               (HasBranchProtectedScope && HasBranchIntoScope));

  }

  // Add a block introduced in this function.

  void addBlock(const BlockDecl *BD) {

    Blocks.insert(BD);

  }

  // Add a __block variable introduced in this function.

  void addByrefBlockVar(VarDecl *VD) {

    ByrefBlockVars.push_back(VD);

  }

  bool isCoroutine() const { return !FirstCoroutineStmtLoc.isInvalid(); }

  void setFirstCoroutineStmt(SourceLocation Loc, StringRef Keyword) {

    assert(FirstCoroutineStmtLoc.isInvalid() &&

                   "first coroutine statement location already set");

    FirstCoroutineStmtLoc = Loc;

    FirstCoroutineStmtKind = llvm::StringSwitch<unsigned char>(Keyword)

            .Case("co_return", 0)

            .Case("co_await", 1)

            .Case("co_yield", 2);

  }

  StringRef getFirstCoroutineStmtKeyword() const {

    assert(FirstCoroutineStmtLoc.isValid()

                   && "no coroutine statement available");

    switch (FirstCoroutineStmtKind) {

    case 0: return "co_return";

    case 1: return "co_await";

    case 2: return "co_yield";

    default:

      llvm_unreachable("FirstCoroutineStmtKind has an invalid value");

    };

  }

  void setNeedsCoroutineSuspends(bool value = true) {

    assert((!value || CoroutineSuspends.first == nullptr) &&

            "we already have valid suspend points");

    NeedsCoroutineSuspends = value;

  }

  bool hasInvalidCoroutineSuspends() const {

    return !NeedsCoroutineSuspends && CoroutineSuspends.first == nullptr;

  }

  void setCoroutineSuspends(Stmt *Initial, Stmt *Final) {

    assert(Initial && Final && "suspend points cannot be null");

    assert(CoroutineSuspends.first == nullptr && "suspend points already set");

    NeedsCoroutineSuspends = false;

    CoroutineSuspends.first = Initial;

    CoroutineSuspends.second = Final;

  }

  /// Clear out the information in this function scope, making it

  /// suitable for reuse.

  void Clear();

  bool isPlainFunction() const { return Kind == SK_Function; }

};

class Capture {

  // There are three categories of capture: capturing 'this', capturing

  // local variables, and C++1y initialized captures (which can have an

  // arbitrary initializer, and don't really capture in the traditional

  // sense at all).

  //

  // There are three ways to capture a local variable:

  //  - capture by copy in the C++11 sense,

  //  - capture by reference in the C++11 sense, and

  //  - __block capture.

  // Lambdas explicitly specify capture by copy or capture by reference.

  // For blocks, __block capture applies to variables with that annotation,

  // variables of reference type are captured by reference, and other

  // variables are captured by copy.

  enum CaptureKind {

    Cap_ByCopy, Cap_ByRef, Cap_Block, Cap_VLA

  };

  union {

    /// If Kind == Cap_VLA, the captured type.

    const VariableArrayType *CapturedVLA;

    /// Otherwise, the captured variable (if any).

    ValueDecl *CapturedVar;

  };

  /// The source location at which the first capture occurred.

  SourceLocation Loc;

  /// The location of the ellipsis that expands a parameter pack.

  SourceLocation EllipsisLoc;

  /// The type as it was captured, which is the type of the non-static data

  /// member that would hold the capture.

  QualType CaptureType;

  /// The CaptureKind of this capture.

  unsigned Kind : 2;

  /// Whether this is a nested capture (a capture of an enclosing capturing

  /// scope's capture).

  unsigned Nested : 1;

  /// Whether this is a capture of '*this'.

  unsigned CapturesThis : 1;

  /// Whether an explicit capture has been odr-used in the body of the

  /// lambda.

  unsigned ODRUsed : 1;

  /// Whether an explicit capture has been non-odr-used in the body of

  /// the lambda.

  unsigned NonODRUsed : 1;

  /// Whether the capture is invalid (a capture was required but the entity is

  /// non-capturable).

  unsigned Invalid : 1;

public:

  Capture(ValueDecl *Var, bool Block, bool ByRef, bool IsNested,

          SourceLocation Loc, SourceLocation EllipsisLoc, QualType CaptureType,

          bool Invalid)

      : CapturedVar(Var), Loc(Loc), EllipsisLoc(EllipsisLoc),

        CaptureType(CaptureType), Kind(Block   ? Cap_Block

                                       : ByRef ? Cap_ByRef

                                               : Cap_ByCopy),

        Nested(IsNested), CapturesThis(false), ODRUsed(false),

        NonODRUsed(false), Invalid(Invalid) {}

  enum IsThisCapture { ThisCapture };

  Capture(IsThisCapture, bool IsNested, SourceLocation Loc,

          QualType CaptureType, const bool ByCopy, bool Invalid)

      : Loc(Loc), CaptureType(CaptureType),

        Kind(ByCopy ? Cap_ByCopy : Cap_ByRef), Nested(IsNested),

        CapturesThis(true), ODRUsed(false), NonODRUsed(false),

        Invalid(Invalid) {}

  enum IsVLACapture { VLACapture };

  Capture(IsVLACapture, const VariableArrayType *VLA, bool IsNested,

          SourceLocation Loc, QualType CaptureType)

      : CapturedVLA(VLA), Loc(Loc), CaptureType(CaptureType), Kind(Cap_VLA),

        Nested(IsNested), CapturesThis(false), ODRUsed(false),

        NonODRUsed(false), Invalid(false) {}

  bool isThisCapture() const { return CapturesThis; }

  bool isVariableCapture() const {

    return !isThisCapture() && !isVLATypeCapture();

  }

  bool isCopyCapture() const { return Kind == Cap_ByCopy; }

  bool isReferenceCapture() const { return Kind == Cap_ByRef; }

  bool isBlockCapture() const { return Kind == Cap_Block; }

  bool isVLATypeCapture() const { return Kind == Cap_VLA; }

  bool isNested() const { return Nested; }

  bool isInvalid() const { return Invalid; }

  /// Determine whether this capture is an init-capture.

  bool isInitCapture() const;

  bool isODRUsed() const { return ODRUsed; }

  bool isNonODRUsed() const { return NonODRUsed; }

  void markUsed(bool IsODRUse) {

    if (IsODRUse)

      ODRUsed = true;

    else

      NonODRUsed = true;

  }

  ValueDecl *getVariable() const {

    assert(isVariableCapture());

    return CapturedVar;

  }

  const VariableArrayType *getCapturedVLAType() const {

    assert(isVLATypeCapture());

    return CapturedVLA;

  }

  /// Retrieve the location at which this variable was captured.

  SourceLocation getLocation() const { return Loc; }

  /// Retrieve the source location of the ellipsis, whose presence

  /// indicates that the capture is a pack expansion.

  SourceLocation getEllipsisLoc() const { return EllipsisLoc; }

  /// Retrieve the capture type for this capture, which is effectively

  /// the type of the non-static data member in the lambda/block structure

  /// that would store this capture.

  QualType getCaptureType() const { return CaptureType; }

};

class CapturingScopeInfo : public FunctionScopeInfo {

protected:

  CapturingScopeInfo(const CapturingScopeInfo&) = default;

public:

  enum ImplicitCaptureStyle {

    ImpCap_None, ImpCap_LambdaByval, ImpCap_LambdaByref, ImpCap_Block,

    ImpCap_CapturedRegion

  };

  ImplicitCaptureStyle ImpCaptureStyle;

  CapturingScopeInfo(DiagnosticsEngine &Diag, ImplicitCaptureStyle Style)

      : FunctionScopeInfo(Diag), ImpCaptureStyle(Style) {}

  /// CaptureMap - A map of captured variables to (index+1) into Captures.

  llvm::DenseMap<ValueDecl *, unsigned> CaptureMap;

  /// CXXThisCaptureIndex - The (index+1) of the capture of 'this';

  /// zero if 'this' is not captured.

  unsigned CXXThisCaptureIndex = 0;

  /// Captures - The captures.

  SmallVector<Capture, 4> Captures;

  /// - Whether the target type of return statements in this context

  /// is deduced (e.g. a lambda or block with omitted return type).

  bool HasImplicitReturnType = false;

  /// ReturnType - The target type of return statements in this context,

  /// or null if unknown.

  QualType ReturnType;

  void addCapture(ValueDecl *Var, bool isBlock, bool isByref, bool isNested,

                  SourceLocation Loc, SourceLocation EllipsisLoc,

                  QualType CaptureType, bool Invalid) {

    Captures.push_back(Capture(Var, isBlock, isByref, isNested, Loc,

                               EllipsisLoc, CaptureType, Invalid));

    CaptureMap[Var] = Captures.size();

  }

  void addVLATypeCapture(SourceLocation Loc, const VariableArrayType *VLAType,

                         QualType CaptureType) {

    Captures.push_back(Capture(Capture::VLACapture, VLAType,

                               /*FIXME: IsNested*/ false, Loc, CaptureType));

  }

  void addThisCapture(bool isNested, SourceLocation Loc, QualType CaptureType,

                      bool ByCopy);

  /// Determine whether the C++ 'this' is captured.

  bool isCXXThisCaptured() const { return CXXThisCaptureIndex != 0; }

  /// Retrieve the capture of C++ 'this', if it has been captured.

  Capture &getCXXThisCapture() {

    assert(isCXXThisCaptured() && "this has not been captured");

    return Captures[CXXThisCaptureIndex - 1];

  }

  /// Determine whether the given variable has been captured.

  bool isCaptured(ValueDecl *Var) const { return CaptureMap.count(Var); }

  /// Determine whether the given variable-array type has been captured.

  bool isVLATypeCaptured(const VariableArrayType *VAT) const;

  /// Retrieve the capture of the given variable, if it has been

  /// captured already.

  Capture &getCapture(ValueDecl *Var) {

    assert(isCaptured(Var) && "Variable has not been captured");

    return Captures[CaptureMap[Var] - 1];

  }

  const Capture &getCapture(ValueDecl *Var) const {

    llvm::DenseMap<ValueDecl *, unsigned>::const_iterator Known =

        CaptureMap.find(Var);

    assert(Known != CaptureMap.end() && "Variable has not been captured");

    return Captures[Known->second - 1];

  }

  static bool classof(const FunctionScopeInfo *FSI) {

    return FSI->Kind == SK_Block || FSI->Kind == SK_Lambda

                                 || FSI->Kind == SK_CapturedRegion;

  }

};

/// Retains information about a block that is currently being parsed.

class BlockScopeInfo final : public CapturingScopeInfo {

public:

  BlockDecl *TheDecl;

  /// TheScope - This is the scope for the block itself, which contains

  /// arguments etc.

  Scope *TheScope;

  /// BlockType - The function type of the block, if one was given.

  /// Its return type may be BuiltinType::Dependent.

  QualType FunctionType;

  BlockScopeInfo(DiagnosticsEngine &Diag, Scope *BlockScope, BlockDecl *Block)

      : CapturingScopeInfo(Diag, ImpCap_Block), TheDecl(Block),

        TheScope(BlockScope) {

    Kind = SK_Block;

  }

  ~BlockScopeInfo() override;

  static bool classof(const FunctionScopeInfo *FSI) {

    return FSI->Kind == SK_Block;

  }

};

/// Retains information about a captured region.

class CapturedRegionScopeInfo final : public CapturingScopeInfo {

public:

  /// The CapturedDecl for this statement.

  CapturedDecl *TheCapturedDecl;

  /// The captured record type.

  RecordDecl *TheRecordDecl;

  /// This is the enclosing scope of the captured region.

  Scope *TheScope;

  /// The implicit parameter for the captured variables.

  ImplicitParamDecl *ContextParam;

  /// The kind of captured region.

  unsigned short CapRegionKind;

  unsigned short OpenMPLevel;

  unsigned short OpenMPCaptureLevel;

  CapturedRegionScopeInfo(DiagnosticsEngine &Diag, Scope *S, CapturedDecl *CD,

                          RecordDecl *RD, ImplicitParamDecl *Context,

                          CapturedRegionKind K, unsigned OpenMPLevel,

                          unsigned OpenMPCaptureLevel)

      : CapturingScopeInfo(Diag, ImpCap_CapturedRegion),

        TheCapturedDecl(CD), TheRecordDecl(RD), TheScope(S),

        ContextParam(Context), CapRegionKind(K), OpenMPLevel(OpenMPLevel),

        OpenMPCaptureLevel(OpenMPCaptureLevel) {

    Kind = SK_CapturedRegion;

  }

  ~CapturedRegionScopeInfo() override;

  /// A descriptive name for the kind of captured region this is.

  StringRef getRegionName() const {

    switch (CapRegionKind) {

    case CR_Default:

      return "default captured statement";

    case CR_ObjCAtFinally:

      return "Objective-C @finally statement";

    case CR_OpenMP:

      return "OpenMP region";

    }

    llvm_unreachable("Invalid captured region kind!");

  }

  static bool classof(const FunctionScopeInfo *FSI) {

    return FSI->Kind == SK_CapturedRegion;

  }

};

class LambdaScopeInfo final :

    public CapturingScopeInfo, public InventedTemplateParameterInfo {

public:

  /// The class that describes the lambda.

  CXXRecordDecl *Lambda = nullptr;

  /// The lambda's compiler-generated \c operator().

  CXXMethodDecl *CallOperator = nullptr;

  /// Source range covering the lambda introducer [...].

  SourceRange IntroducerRange;

  /// Source location of the '&' or '=' specifying the default capture

  /// type, if any.

  SourceLocation CaptureDefaultLoc;

  /// The number of captures in the \c Captures list that are

  /// explicit captures.

  unsigned NumExplicitCaptures = 0;

  /// Whether this is a mutable lambda.