369 lines
14 KiB
C++
369 lines
14 KiB
C++
//===------ CXXInheritance.h - C++ Inheritance ------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file provides routines that help analyzing C++ inheritance hierarchies.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_AST_CXXINHERITANCE_H
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#define LLVM_CLANG_AST_CXXINHERITANCE_H
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#include "clang/AST/DeclarationName.h"
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#include "clang/AST/DeclBase.h"
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#include "clang/AST/DeclCXX.h"
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#include "clang/AST/Type.h"
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#include "clang/AST/TypeOrdering.h"
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#include "llvm/ADT/MapVector.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include <list>
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#include <map>
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#include <cassert>
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namespace clang {
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class CXXBaseSpecifier;
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class CXXMethodDecl;
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class CXXRecordDecl;
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class NamedDecl;
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/// \brief Represents an element in a path from a derived class to a
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/// base class.
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///
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/// Each step in the path references the link from a
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/// derived class to one of its direct base classes, along with a
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/// base "number" that identifies which base subobject of the
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/// original derived class we are referencing.
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struct CXXBasePathElement {
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/// \brief The base specifier that states the link from a derived
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/// class to a base class, which will be followed by this base
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/// path element.
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const CXXBaseSpecifier *Base;
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/// \brief The record decl of the class that the base is a base of.
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const CXXRecordDecl *Class;
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/// \brief Identifies which base class subobject (of type
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/// \c Base->getType()) this base path element refers to.
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///
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/// This value is only valid if \c !Base->isVirtual(), because there
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/// is no base numbering for the zero or one virtual bases of a
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/// given type.
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int SubobjectNumber;
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};
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/// \brief Represents a path from a specific derived class
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/// (which is not represented as part of the path) to a particular
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/// (direct or indirect) base class subobject.
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///
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/// Individual elements in the path are described by the \c CXXBasePathElement
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/// structure, which captures both the link from a derived class to one of its
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/// direct bases and identification describing which base class
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/// subobject is being used.
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class CXXBasePath : public SmallVector<CXXBasePathElement, 4> {
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public:
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CXXBasePath() : Access(AS_public) {}
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/// \brief The access along this inheritance path. This is only
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/// calculated when recording paths. AS_none is a special value
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/// used to indicate a path which permits no legal access.
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AccessSpecifier Access;
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/// \brief The set of declarations found inside this base class
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/// subobject.
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DeclContext::lookup_result Decls;
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void clear() {
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SmallVectorImpl<CXXBasePathElement>::clear();
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Access = AS_public;
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}
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};
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/// BasePaths - Represents the set of paths from a derived class to
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/// one of its (direct or indirect) bases. For example, given the
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/// following class hierarchy:
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///
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/// @code
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/// class A { };
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/// class B : public A { };
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/// class C : public A { };
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/// class D : public B, public C{ };
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/// @endcode
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///
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/// There are two potential BasePaths to represent paths from D to a
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/// base subobject of type A. One path is (D,0) -> (B,0) -> (A,0)
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/// and another is (D,0)->(C,0)->(A,1). These two paths actually
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/// refer to two different base class subobjects of the same type,
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/// so the BasePaths object refers to an ambiguous path. On the
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/// other hand, consider the following class hierarchy:
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///
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/// @code
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/// class A { };
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/// class B : public virtual A { };
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/// class C : public virtual A { };
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/// class D : public B, public C{ };
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/// @endcode
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///
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/// Here, there are two potential BasePaths again, (D, 0) -> (B, 0)
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/// -> (A,v) and (D, 0) -> (C, 0) -> (A, v), but since both of them
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/// refer to the same base class subobject of type A (the virtual
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/// one), there is no ambiguity.
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class CXXBasePaths {
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/// \brief The type from which this search originated.
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CXXRecordDecl *Origin;
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/// Paths - The actual set of paths that can be taken from the
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/// derived class to the same base class.
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std::list<CXXBasePath> Paths;
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/// ClassSubobjects - Records the class subobjects for each class
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/// type that we've seen. The first element in the pair says
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/// whether we found a path to a virtual base for that class type,
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/// while the element contains the number of non-virtual base
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/// class subobjects for that class type. The key of the map is
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/// the cv-unqualified canonical type of the base class subobject.
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llvm::SmallDenseMap<QualType, std::pair<bool, unsigned>, 8> ClassSubobjects;
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/// FindAmbiguities - Whether Sema::IsDerivedFrom should try find
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/// ambiguous paths while it is looking for a path from a derived
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/// type to a base type.
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bool FindAmbiguities;
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/// RecordPaths - Whether Sema::IsDerivedFrom should record paths
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/// while it is determining whether there are paths from a derived
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/// type to a base type.
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bool RecordPaths;
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/// DetectVirtual - Whether Sema::IsDerivedFrom should abort the search
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/// if it finds a path that goes across a virtual base. The virtual class
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/// is also recorded.
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bool DetectVirtual;
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/// ScratchPath - A BasePath that is used by Sema::lookupInBases
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/// to help build the set of paths.
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CXXBasePath ScratchPath;
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/// DetectedVirtual - The base class that is virtual.
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const RecordType *DetectedVirtual;
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/// \brief Array of the declarations that have been found. This
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/// array is constructed only if needed, e.g., to iterate over the
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/// results within LookupResult.
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NamedDecl **DeclsFound;
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unsigned NumDeclsFound;
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friend class CXXRecordDecl;
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void ComputeDeclsFound();
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bool lookupInBases(ASTContext &Context,
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const CXXRecordDecl *Record,
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CXXRecordDecl::BaseMatchesCallback *BaseMatches,
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void *UserData);
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public:
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typedef std::list<CXXBasePath>::iterator paths_iterator;
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typedef std::list<CXXBasePath>::const_iterator const_paths_iterator;
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typedef NamedDecl **decl_iterator;
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/// BasePaths - Construct a new BasePaths structure to record the
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/// paths for a derived-to-base search.
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explicit CXXBasePaths(bool FindAmbiguities = true,
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bool RecordPaths = true,
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bool DetectVirtual = true)
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: FindAmbiguities(FindAmbiguities), RecordPaths(RecordPaths),
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DetectVirtual(DetectVirtual), DetectedVirtual(0), DeclsFound(0),
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NumDeclsFound(0) { }
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~CXXBasePaths() { delete [] DeclsFound; }
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paths_iterator begin() { return Paths.begin(); }
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paths_iterator end() { return Paths.end(); }
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const_paths_iterator begin() const { return Paths.begin(); }
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const_paths_iterator end() const { return Paths.end(); }
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CXXBasePath& front() { return Paths.front(); }
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const CXXBasePath& front() const { return Paths.front(); }
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decl_iterator found_decls_begin();
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decl_iterator found_decls_end();
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/// \brief Determine whether the path from the most-derived type to the
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/// given base type is ambiguous (i.e., it refers to multiple subobjects of
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/// the same base type).
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bool isAmbiguous(CanQualType BaseType);
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/// \brief Whether we are finding multiple paths to detect ambiguities.
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bool isFindingAmbiguities() const { return FindAmbiguities; }
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/// \brief Whether we are recording paths.
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bool isRecordingPaths() const { return RecordPaths; }
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/// \brief Specify whether we should be recording paths or not.
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void setRecordingPaths(bool RP) { RecordPaths = RP; }
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/// \brief Whether we are detecting virtual bases.
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bool isDetectingVirtual() const { return DetectVirtual; }
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/// \brief The virtual base discovered on the path (if we are merely
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/// detecting virtuals).
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const RecordType* getDetectedVirtual() const {
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return DetectedVirtual;
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}
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/// \brief Retrieve the type from which this base-paths search
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/// began
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CXXRecordDecl *getOrigin() const { return Origin; }
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void setOrigin(CXXRecordDecl *Rec) { Origin = Rec; }
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/// \brief Clear the base-paths results.
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void clear();
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/// \brief Swap this data structure's contents with another CXXBasePaths
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/// object.
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void swap(CXXBasePaths &Other);
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};
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/// \brief Uniquely identifies a virtual method within a class
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/// hierarchy by the method itself and a class subobject number.
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struct UniqueVirtualMethod {
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UniqueVirtualMethod() : Method(0), Subobject(0), InVirtualSubobject(0) { }
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UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject,
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const CXXRecordDecl *InVirtualSubobject)
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: Method(Method), Subobject(Subobject),
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InVirtualSubobject(InVirtualSubobject) { }
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/// \brief The overriding virtual method.
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CXXMethodDecl *Method;
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/// \brief The subobject in which the overriding virtual method
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/// resides.
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unsigned Subobject;
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/// \brief The virtual base class subobject of which this overridden
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/// virtual method is a part. Note that this records the closest
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/// derived virtual base class subobject.
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const CXXRecordDecl *InVirtualSubobject;
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friend bool operator==(const UniqueVirtualMethod &X,
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const UniqueVirtualMethod &Y) {
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return X.Method == Y.Method && X.Subobject == Y.Subobject &&
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X.InVirtualSubobject == Y.InVirtualSubobject;
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}
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friend bool operator!=(const UniqueVirtualMethod &X,
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const UniqueVirtualMethod &Y) {
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return !(X == Y);
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}
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};
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/// \brief The set of methods that override a given virtual method in
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/// each subobject where it occurs.
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///
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/// The first part of the pair is the subobject in which the
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/// overridden virtual function occurs, while the second part of the
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/// pair is the virtual method that overrides it (including the
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/// subobject in which that virtual function occurs).
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class OverridingMethods {
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typedef SmallVector<UniqueVirtualMethod, 4> ValuesT;
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typedef llvm::MapVector<unsigned, ValuesT> MapType;
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MapType Overrides;
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public:
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// Iterate over the set of subobjects that have overriding methods.
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typedef MapType::iterator iterator;
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typedef MapType::const_iterator const_iterator;
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iterator begin() { return Overrides.begin(); }
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const_iterator begin() const { return Overrides.begin(); }
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iterator end() { return Overrides.end(); }
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const_iterator end() const { return Overrides.end(); }
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unsigned size() const { return Overrides.size(); }
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// Iterate over the set of overriding virtual methods in a given
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// subobject.
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typedef SmallVector<UniqueVirtualMethod, 4>::iterator
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overriding_iterator;
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typedef SmallVector<UniqueVirtualMethod, 4>::const_iterator
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overriding_const_iterator;
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// Add a new overriding method for a particular subobject.
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void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding);
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// Add all of the overriding methods from "other" into overrides for
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// this method. Used when merging the overrides from multiple base
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// class subobjects.
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void add(const OverridingMethods &Other);
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// Replace all overriding virtual methods in all subobjects with the
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// given virtual method.
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void replaceAll(UniqueVirtualMethod Overriding);
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};
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/// \brief A mapping from each virtual member function to its set of
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/// final overriders.
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///
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/// Within a class hierarchy for a given derived class, each virtual
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/// member function in that hierarchy has one or more "final
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/// overriders" (C++ [class.virtual]p2). A final overrider for a
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/// virtual function "f" is the virtual function that will actually be
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/// invoked when dispatching a call to "f" through the
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/// vtable. Well-formed classes have a single final overrider for each
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/// virtual function; in abstract classes, the final overrider for at
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/// least one virtual function is a pure virtual function. Due to
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/// multiple, virtual inheritance, it is possible for a class to have
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/// more than one final overrider. Athough this is an error (per C++
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/// [class.virtual]p2), it is not considered an error here: the final
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/// overrider map can represent multiple final overriders for a
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/// method, and it is up to the client to determine whether they are
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/// problem. For example, the following class \c D has two final
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/// overriders for the virtual function \c A::f(), one in \c C and one
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/// in \c D:
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///
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/// \code
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/// struct A { virtual void f(); };
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/// struct B : virtual A { virtual void f(); };
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/// struct C : virtual A { virtual void f(); };
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/// struct D : B, C { };
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/// \endcode
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///
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/// This data structure contaings a mapping from every virtual
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/// function *that does not override an existing virtual function* and
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/// in every subobject where that virtual function occurs to the set
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/// of virtual functions that override it. Thus, the same virtual
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/// function \c A::f can actually occur in multiple subobjects of type
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/// \c A due to multiple inheritance, and may be overriden by
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/// different virtual functions in each, as in the following example:
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///
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/// \code
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/// struct A { virtual void f(); };
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/// struct B : A { virtual void f(); };
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/// struct C : A { virtual void f(); };
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/// struct D : B, C { };
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/// \endcode
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///
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/// Unlike in the previous example, where the virtual functions \c
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/// B::f and \c C::f both overrode \c A::f in the same subobject of
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/// type \c A, in this example the two virtual functions both override
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/// \c A::f but in *different* subobjects of type A. This is
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/// represented by numbering the subobjects in which the overridden
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/// and the overriding virtual member functions are located. Subobject
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/// 0 represents the virtua base class subobject of that type, while
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/// subobject numbers greater than 0 refer to non-virtual base class
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/// subobjects of that type.
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class CXXFinalOverriderMap
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: public llvm::MapVector<const CXXMethodDecl *, OverridingMethods> { };
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/// \brief A set of all the primary bases for a class.
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class CXXIndirectPrimaryBaseSet
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: public llvm::SmallSet<const CXXRecordDecl*, 32> { };
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} // end namespace clang
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#endif
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