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 //===- Scope.h - Scope interface --------------------------------*- 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 the Scope interface.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_SEMA_SCOPE_H
 #define LLVM_CLANG_SEMA_SCOPE_H
 
 #include "clang/AST/Decl.h"
 #include "clang/Basic/Diagnostic.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/iterator_range.h"
 #include <cassert>
 #include <optional>
 
 namespace llvm {
 
 class raw_ostream;
 
 } // namespace llvm
 
 namespace clang {
 
 class Decl;
 class DeclContext;
 class UsingDirectiveDecl;
 class VarDecl;
 
 /// Scope - A scope is a transient data structure that is used while parsing the
 /// program.  It assists with resolving identifiers to the appropriate
 /// declaration.
 class Scope {
 public:
   /// ScopeFlags - These are bitfields that are or'd together when creating a
   /// scope, which defines the sorts of things the scope contains.
   enum ScopeFlags {
     // A bitfield value representing no scopes.
     NoScope = 0,
 
     /// This indicates that the scope corresponds to a function, which
     /// means that labels are set here.
     FnScope = 0x01,
 
     /// This is a while, do, switch, for, etc that can have break
     /// statements embedded into it.
     BreakScope = 0x02,
 
     /// This is a while, do, for, which can have continue statements
     /// embedded into it.
     ContinueScope = 0x04,
 
     /// This is a scope that can contain a declaration.  Some scopes
     /// just contain loop constructs but don't contain decls.
     DeclScope = 0x08,
 
     /// The controlling scope in a if/switch/while/for statement.
     ControlScope = 0x10,
 
     /// The scope of a struct/union/class definition.
     ClassScope = 0x20,
 
     /// This is a scope that corresponds to a block/closure object.
     /// Blocks serve as top-level scopes for some objects like labels, they
     /// also prevent things like break and continue.  BlockScopes always have
     /// the FnScope and DeclScope flags set as well.
     BlockScope = 0x40,
 
     /// This is a scope that corresponds to the
     /// template parameters of a C++ template. Template parameter
     /// scope starts at the 'template' keyword and ends when the
     /// template declaration ends.
     TemplateParamScope = 0x80,
 
     /// This is a scope that corresponds to the
     /// parameters within a function prototype.
     FunctionPrototypeScope = 0x100,
 
     /// This is a scope that corresponds to the parameters within
     /// a function prototype for a function declaration (as opposed to any
     /// other kind of function declarator). Always has FunctionPrototypeScope
     /// set as well.
     FunctionDeclarationScope = 0x200,
 
     /// This is a scope that corresponds to the Objective-C
     /// \@catch statement.
     AtCatchScope = 0x400,
 
     /// This scope corresponds to an Objective-C method body.
     /// It always has FnScope and DeclScope set as well.
     ObjCMethodScope = 0x800,
 
     /// This is a scope that corresponds to a switch statement.
     SwitchScope = 0x1000,
 
     /// This is the scope of a C++ try statement.
     TryScope = 0x2000,
 
     /// This is the scope for a function-level C++ try or catch scope.
     FnTryCatchScope = 0x4000,
 
     /// This is the scope of OpenMP executable directive.
     OpenMPDirectiveScope = 0x8000,
 
     /// This is the scope of some OpenMP loop directive.
     OpenMPLoopDirectiveScope = 0x10000,
 
     /// This is the scope of some OpenMP simd directive.
     /// For example, it is used for 'omp simd', 'omp for simd'.
     /// This flag is propagated to children scopes.
     OpenMPSimdDirectiveScope = 0x20000,
 
     /// This scope corresponds to an enum.
     EnumScope = 0x40000,
 
     /// This scope corresponds to an SEH try.
     SEHTryScope = 0x80000,
 
     /// This scope corresponds to an SEH except.
     SEHExceptScope = 0x100000,
 
     /// We are currently in the filter expression of an SEH except block.
     SEHFilterScope = 0x200000,
 
     /// This is a compound statement scope.
     CompoundStmtScope = 0x400000,
 
     /// We are between inheritance colon and the real class/struct definition
     /// scope.
     ClassInheritanceScope = 0x800000,
 
     /// This is the scope of a C++ catch statement.
     CatchScope = 0x1000000,
 
     /// This is a scope in which a condition variable is currently being
     /// parsed. If such a scope is a ContinueScope, it's invalid to jump to the
     /// continue block from here.
     ConditionVarScope = 0x2000000,
 
     /// This is a scope of some OpenMP directive with
     /// order clause which specifies concurrent
     OpenMPOrderClauseScope = 0x4000000,
     /// This is the scope for a lambda, after the lambda introducer.
     /// Lambdas need two FunctionPrototypeScope scopes (because there is a
     /// template scope in between), the outer scope does not increase the
     /// depth of recursion.
     LambdaScope = 0x8000000,
     /// This is the scope of an OpenACC Compute Construct, which restricts
     /// jumping into/out of it. We also use this to represent 'combined'
     /// constructs, since they have the same behavior.
     OpenACCComputeConstructScope = 0x10000000,
 
     /// This is a scope of type alias declaration.
     TypeAliasScope = 0x20000000,
 
     /// This is a scope of friend declaration.
     FriendScope = 0x40000000,
   };
 
 private:
   /// The parent scope for this scope.  This is null for the translation-unit
   /// scope.
   Scope *AnyParent;
 
   /// Flags - This contains a set of ScopeFlags, which indicates how the scope
   /// interrelates with other control flow statements.
   unsigned Flags;
 
   /// Depth - This is the depth of this scope.  The translation-unit scope has
   /// depth 0.
   unsigned short Depth;
 
   /// Declarations with static linkage are mangled with the number of
   /// scopes seen as a component.
   unsigned short MSLastManglingNumber;
 
   unsigned short MSCurManglingNumber;
 
   /// PrototypeDepth - This is the number of function prototype scopes
   /// enclosing this scope, including this scope.
   unsigned short PrototypeDepth;
 
   /// PrototypeIndex - This is the number of parameters currently
   /// declared in this scope.
   unsigned short PrototypeIndex;
 
   /// FnParent - If this scope has a parent scope that is a function body, this
   /// pointer is non-null and points to it.  This is used for label processing.
   Scope *FnParent;
   Scope *MSLastManglingParent;
 
   /// BreakParent/ContinueParent - This is a direct link to the innermost
   /// BreakScope/ContinueScope which contains the contents of this scope
   /// for control flow purposes (and might be this scope itself), or null
   /// if there is no such scope.
   Scope *BreakParent, *ContinueParent;
 
   /// BlockParent - This is a direct link to the immediately containing
   /// BlockScope if this scope is not one, or null if there is none.
   Scope *BlockParent;
 
   /// TemplateParamParent - This is a direct link to the
   /// immediately containing template parameter scope. In the
   /// case of nested templates, template parameter scopes can have
   /// other template parameter scopes as parents.
   Scope *TemplateParamParent;
 
   /// DeclScopeParent - This is a direct link to the immediately containing
   /// DeclScope, i.e. scope which can contain declarations.
   Scope *DeclParent;
 
   /// DeclsInScope - This keeps track of all declarations in this scope.  When
   /// the declaration is added to the scope, it is set as the current
   /// declaration for the identifier in the IdentifierTable.  When the scope is
   /// popped, these declarations are removed from the IdentifierTable's notion
   /// of current declaration.  It is up to the current Action implementation to
   /// implement these semantics.
   using DeclSetTy = llvm::SmallPtrSet<Decl *, 32>;
   DeclSetTy DeclsInScope;
 
   /// The DeclContext with which this scope is associated. For
   /// example, the entity of a class scope is the class itself, the
   /// entity of a function scope is a function, etc.
   DeclContext *Entity;
 
   using UsingDirectivesTy = SmallVector<UsingDirectiveDecl *, 2>;
   UsingDirectivesTy UsingDirectives;
 
   /// Used to determine if errors occurred in this scope.
   DiagnosticErrorTrap ErrorTrap;
 
   /// A single NRVO candidate variable in this scope.
   /// There are three possible values:
   ///  1) pointer to VarDecl that denotes NRVO candidate itself.
   ///  2) nullptr value means that NRVO is not allowed in this scope
   ///     (e.g. return a function parameter).
   ///  3) std::nullopt value means that there is no NRVO candidate in this scope
   ///     (i.e. there are no return statements in this scope).
   std::optional<VarDecl *> NRVO;
 
   /// Represents return slots for NRVO candidates in the current scope.
   /// If a variable is present in this set, it means that a return slot is
   /// available for this variable in the current scope.
   llvm::SmallPtrSet<VarDecl *, 8> ReturnSlots;
 
   void setFlags(Scope *Parent, unsigned F);
 
 public:
   Scope(Scope *Parent, unsigned ScopeFlags, DiagnosticsEngine &Diag)
       : ErrorTrap(Diag) {
     Init(Parent, ScopeFlags);
   }
 
   /// getFlags - Return the flags for this scope.
   unsigned getFlags() const { return Flags; }
 
   void setFlags(unsigned F) { setFlags(getParent(), F); }
 
   /// isBlockScope - Return true if this scope correspond to a closure.
   bool isBlockScope() const { return Flags & BlockScope; }
 
   /// getParent - Return the scope that this is nested in.
   const Scope *getParent() const { return AnyParent; }
   Scope *getParent() { return AnyParent; }
 
   /// getFnParent - Return the closest scope that is a function body.
   const Scope *getFnParent() const { return FnParent; }
   Scope *getFnParent() { return FnParent; }
 
   const Scope *getMSLastManglingParent() const {
     return MSLastManglingParent;
   }
   Scope *getMSLastManglingParent() { return MSLastManglingParent; }
 
   /// getContinueParent - Return the closest scope that a continue statement
   /// would be affected by.
   Scope *getContinueParent() {
     return ContinueParent;
   }
 
   const Scope *getContinueParent() const {
     return const_cast<Scope*>(this)->getContinueParent();
   }
 
   // Set whether we're in the scope of a condition variable, where 'continue'
   // is disallowed despite being a continue scope.
   void setIsConditionVarScope(bool InConditionVarScope) {
     Flags = (Flags & ~ConditionVarScope) |
             (InConditionVarScope ? ConditionVarScope : 0);
   }
 
   bool isConditionVarScope() const {
     return Flags & ConditionVarScope;
   }
 
   /// getBreakParent - Return the closest scope that a break statement
   /// would be affected by.
   Scope *getBreakParent() {
     return BreakParent;
   }
   const Scope *getBreakParent() const {
     return const_cast<Scope*>(this)->getBreakParent();
   }
 
   Scope *getBlockParent() { return BlockParent; }
   const Scope *getBlockParent() const { return BlockParent; }
 
   Scope *getTemplateParamParent() { return TemplateParamParent; }
   const Scope *getTemplateParamParent() const { return TemplateParamParent; }
 
   Scope *getDeclParent() { return DeclParent; }
   const Scope *getDeclParent() const { return DeclParent; }
 
   /// Returns the depth of this scope. The translation-unit has scope depth 0.
   unsigned getDepth() const { return Depth; }
 
   /// Returns the number of function prototype scopes in this scope
   /// chain.
   unsigned getFunctionPrototypeDepth() const {
     return PrototypeDepth;
   }
 
   /// Return the number of parameters declared in this function
   /// prototype, increasing it by one for the next call.
   unsigned getNextFunctionPrototypeIndex() {
     assert(isFunctionPrototypeScope());
     return PrototypeIndex++;
   }
 
   using decl_range = llvm::iterator_range<DeclSetTy::iterator>;
 
   decl_range decls() const {
     return decl_range(DeclsInScope.begin(), DeclsInScope.end());
   }
 
   bool decl_empty() const { return DeclsInScope.empty(); }
 
   void AddDecl(Decl *D) {
     if (auto *VD = dyn_cast<VarDecl>(D))
       if (!isa<ParmVarDecl>(VD))
         ReturnSlots.insert(VD);
 
     DeclsInScope.insert(D);
   }
 
   void RemoveDecl(Decl *D) { DeclsInScope.erase(D); }
 
   void incrementMSManglingNumber() {
     if (Scope *MSLMP = getMSLastManglingParent()) {
       MSLMP->MSLastManglingNumber += 1;
       MSCurManglingNumber += 1;
     }
   }
 
   void decrementMSManglingNumber() {
     if (Scope *MSLMP = getMSLastManglingParent()) {
       MSLMP->MSLastManglingNumber -= 1;
       MSCurManglingNumber -= 1;
     }
   }
 
   unsigned getMSLastManglingNumber() const {
     if (const Scope *MSLMP = getMSLastManglingParent())
       return MSLMP->MSLastManglingNumber;
     return 1;
   }
 
   unsigned getMSCurManglingNumber() const {
     return MSCurManglingNumber;
   }
 
   /// isDeclScope - Return true if this is the scope that the specified decl is
   /// declared in.
   bool isDeclScope(const Decl *D) const { return DeclsInScope.contains(D); }
 
   /// Get the entity corresponding to this scope.
   DeclContext *getEntity() const {
     return isTemplateParamScope() ? nullptr : Entity;
   }
 
   /// Get the DeclContext in which to continue unqualified lookup after a
   /// lookup in this scope.
   DeclContext *getLookupEntity() const { return Entity; }
 
   void setEntity(DeclContext *E) {
     assert(!isTemplateParamScope() &&
            "entity associated with template param scope");
     Entity = E;
   }
   void setLookupEntity(DeclContext *E) { Entity = E; }
 
   /// Determine whether any unrecoverable errors have occurred within this
   /// scope. Note that this may return false even if the scope contains invalid
   /// declarations or statements, if the errors for those invalid constructs
   /// were suppressed because some prior invalid construct was referenced.
   bool hasUnrecoverableErrorOccurred() const {
     return ErrorTrap.hasUnrecoverableErrorOccurred();
   }
 
   /// isFunctionScope() - Return true if this scope is a function scope.
   bool isFunctionScope() const { return getFlags() & Scope::FnScope; }
 
   /// isClassScope - Return true if this scope is a class/struct/union scope.
   bool isClassScope() const { return getFlags() & Scope::ClassScope; }
 
   /// Determines whether this scope is between inheritance colon and the real
   /// class/struct definition.
   bool isClassInheritanceScope() const {
     return getFlags() & Scope::ClassInheritanceScope;
   }
 
   /// isInCXXInlineMethodScope - Return true if this scope is a C++ inline
   /// method scope or is inside one.
   bool isInCXXInlineMethodScope() const {
     if (const Scope *FnS = getFnParent()) {
       assert(FnS->getParent() && "TUScope not created?");
       return FnS->getParent()->isClassScope();
     }
     return false;
   }
 
   /// isInObjcMethodScope - Return true if this scope is, or is contained in, an
   /// Objective-C method body.  Note that this method is not constant time.
   bool isInObjcMethodScope() const {
     for (const Scope *S = this; S; S = S->getParent()) {
       // If this scope is an objc method scope, then we succeed.
       if (S->getFlags() & ObjCMethodScope)
         return true;
     }
     return false;
   }
 
   /// isInObjcMethodOuterScope - Return true if this scope is an
   /// Objective-C method outer most body.
   bool isInObjcMethodOuterScope() const {
     if (const Scope *S = this) {
       // If this scope is an objc method scope, then we succeed.
       if (S->getFlags() & ObjCMethodScope)
         return true;
     }
     return false;
   }
 
   /// isTemplateParamScope - Return true if this scope is a C++
   /// template parameter scope.
   bool isTemplateParamScope() const {
     return getFlags() & Scope::TemplateParamScope;
   }
 
   /// isFunctionPrototypeScope - Return true if this scope is a
   /// function prototype scope.
   bool isFunctionPrototypeScope() const {
     return getFlags() & Scope::FunctionPrototypeScope;
   }
 
   /// isFunctionDeclarationScope - Return true if this scope is a
   /// function prototype scope.
   bool isFunctionDeclarationScope() const {
     return getFlags() & Scope::FunctionDeclarationScope;
   }
 
   /// isAtCatchScope - Return true if this scope is \@catch.
   bool isAtCatchScope() const {
     return getFlags() & Scope::AtCatchScope;
   }
 
   /// isCatchScope - Return true if this scope is a C++ catch statement.
   bool isCatchScope() const { return getFlags() & Scope::CatchScope; }
 
   /// isSwitchScope - Return true if this scope is a switch scope.
   bool isSwitchScope() const {
     for (const Scope *S = this; S; S = S->getParent()) {
       if (S->getFlags() & Scope::SwitchScope)
         return true;
       else if (S->getFlags() & (Scope::FnScope | Scope::ClassScope |
                                 Scope::BlockScope | Scope::TemplateParamScope |
                                 Scope::FunctionPrototypeScope |
                                 Scope::AtCatchScope | Scope::ObjCMethodScope))
         return false;
     }
     return false;
   }
 
   /// Return true if this scope is a loop.
   bool isLoopScope() const {
     // 'switch' is the only loop that is not a 'break' scope as well, so we can
     // just check BreakScope and not SwitchScope.
     return (getFlags() & Scope::BreakScope) &&
            !(getFlags() & Scope::SwitchScope);
   }
 
   /// Determines whether this scope is the OpenMP directive scope
   bool isOpenMPDirectiveScope() const {
     return (getFlags() & Scope::OpenMPDirectiveScope);
   }
 
   /// Determine whether this scope is some OpenMP loop directive scope
   /// (for example, 'omp for', 'omp simd').
   bool isOpenMPLoopDirectiveScope() const {
     if (getFlags() & Scope::OpenMPLoopDirectiveScope) {
       assert(isOpenMPDirectiveScope() &&
              "OpenMP loop directive scope is not a directive scope");
       return true;
     }
     return false;
   }
 
   /// Determine whether this scope is (or is nested into) some OpenMP
   /// loop simd directive scope (for example, 'omp simd', 'omp for simd').
   bool isOpenMPSimdDirectiveScope() const {
     return getFlags() & Scope::OpenMPSimdDirectiveScope;
   }
 
   /// Determine whether this scope is a loop having OpenMP loop
   /// directive attached.
   bool isOpenMPLoopScope() const {
     const Scope *P = getParent();
     return P && P->isOpenMPLoopDirectiveScope();
   }
 
   /// Determine whether this scope is some OpenMP directive with
   /// order clause which specifies concurrent scope.
   bool isOpenMPOrderClauseScope() const {
     return getFlags() & Scope::OpenMPOrderClauseScope;
   }
 
   /// Determine whether this scope is the statement associated with an OpenACC
   /// Compute construct directive.
   bool isOpenACCComputeConstructScope() const {
     return getFlags() & Scope::OpenACCComputeConstructScope;
   }
 
   /// Determine if this scope (or its parents) are a compute construct. If the
   /// argument is provided, the search will stop at any of the specified scopes.
   /// Otherwise, it will stop only at the normal 'no longer search' scopes.
   bool isInOpenACCComputeConstructScope(ScopeFlags Flags = NoScope) const {
     for (const Scope *S = this; S; S = S->getParent()) {
       if (S->isOpenACCComputeConstructScope())
         return true;
 
       if (S->getFlags() & Flags)
         return false;
 
       else if (S->getFlags() &
                (Scope::FnScope | Scope::ClassScope | Scope::BlockScope |
                 Scope::TemplateParamScope | Scope::FunctionPrototypeScope |
                 Scope::AtCatchScope | Scope::ObjCMethodScope))
         return false;
     }
     return false;
   }
 
   /// Determine whether this scope is a while/do/for statement, which can have
   /// continue statements embedded into it.
   bool isContinueScope() const {
     return getFlags() & ScopeFlags::ContinueScope;
   }
 
   /// Determine whether this scope is a C++ 'try' block.
   bool isTryScope() const { return getFlags() & Scope::TryScope; }
 
   /// Determine whether this scope is a function-level C++ try or catch scope.
   bool isFnTryCatchScope() const {
     return getFlags() & ScopeFlags::FnTryCatchScope;
   }
 
   /// Determine whether this scope is a SEH '__try' block.
   bool isSEHTryScope() const { return getFlags() & Scope::SEHTryScope; }
 
   /// Determine whether this scope is a SEH '__except' block.
   bool isSEHExceptScope() const { return getFlags() & Scope::SEHExceptScope; }
 
   /// Determine whether this scope is a compound statement scope.
   bool isCompoundStmtScope() const {
     return getFlags() & Scope::CompoundStmtScope;
   }
 
   /// Determine whether this scope is a controlling scope in a
   /// if/switch/while/for statement.
   bool isControlScope() const { return getFlags() & Scope::ControlScope; }
 
   /// Determine whether this scope is a type alias scope.
   bool isTypeAliasScope() const { return getFlags() & Scope::TypeAliasScope; }
 
   /// Determine whether this scope is a friend scope.
   bool isFriendScope() const { return getFlags() & Scope::FriendScope; }
 
   /// Returns if rhs has a higher scope depth than this.
   ///
   /// The caller is responsible for calling this only if one of the two scopes
   /// is an ancestor of the other.
   bool Contains(const Scope& rhs) const { return Depth < rhs.Depth; }
 
   /// containedInPrototypeScope - Return true if this or a parent scope
   /// is a FunctionPrototypeScope.
   bool containedInPrototypeScope() const;
 
   void PushUsingDirective(UsingDirectiveDecl *UDir) {
     UsingDirectives.push_back(UDir);
   }
 
   using using_directives_range =
       llvm::iterator_range<UsingDirectivesTy::iterator>;
 
   using_directives_range using_directives() {
     return using_directives_range(UsingDirectives.begin(),
                                   UsingDirectives.end());
   }
 
   void updateNRVOCandidate(VarDecl *VD);
 
   void applyNRVO();
 
   /// Init - This is used by the parser to implement scope caching.
   void Init(Scope *parent, unsigned flags);
 
   /// Sets up the specified scope flags and adjusts the scope state
   /// variables accordingly.
   void AddFlags(unsigned Flags);
 
   void dumpImpl(raw_ostream &OS) const;
   void dump() const;
 };
 
 } // namespace clang
 
 #endif // LLVM_CLANG_SEMA_SCOPE_H

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