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CXXInheritance.h
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1 //===------ CXXInheritance.h - C++ Inheritance ------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file provides routines that help analyzing C++ inheritance hierarchies.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_AST_CXXINHERITANCE_H
15 #define LLVM_CLANG_AST_CXXINHERITANCE_H
16 
17 #include "clang/AST/DeclBase.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/Type.h"
20 #include "clang/AST/TypeOrdering.h"
21 #include "llvm/ADT/MapVector.h"
22 #include "llvm/ADT/SmallSet.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include <cassert>
25 #include <list>
26 
27 namespace clang {
28 
29 class CXXBaseSpecifier;
30 class CXXMethodDecl;
31 class CXXRecordDecl;
32 class NamedDecl;
33 
34 /// \brief Represents an element in a path from a derived class to a
35 /// base class.
36 ///
37 /// Each step in the path references the link from a
38 /// derived class to one of its direct base classes, along with a
39 /// base "number" that identifies which base subobject of the
40 /// original derived class we are referencing.
42  /// \brief The base specifier that states the link from a derived
43  /// class to a base class, which will be followed by this base
44  /// path element.
46 
47  /// \brief The record decl of the class that the base is a base of.
49 
50  /// \brief Identifies which base class subobject (of type
51  /// \c Base->getType()) this base path element refers to.
52  ///
53  /// This value is only valid if \c !Base->isVirtual(), because there
54  /// is no base numbering for the zero or one virtual bases of a
55  /// given type.
57 };
58 
59 /// \brief Represents a path from a specific derived class
60 /// (which is not represented as part of the path) to a particular
61 /// (direct or indirect) base class subobject.
62 ///
63 /// Individual elements in the path are described by the \c CXXBasePathElement
64 /// structure, which captures both the link from a derived class to one of its
65 /// direct bases and identification describing which base class
66 /// subobject is being used.
67 class CXXBasePath : public SmallVector<CXXBasePathElement, 4> {
68 public:
69  CXXBasePath() : Access(AS_public) {}
70 
71  /// \brief The access along this inheritance path. This is only
72  /// calculated when recording paths. AS_none is a special value
73  /// used to indicate a path which permits no legal access.
75 
76  /// \brief The set of declarations found inside this base class
77  /// subobject.
79 
80  void clear() {
82  Access = AS_public;
83  }
84 };
85 
86 /// BasePaths - Represents the set of paths from a derived class to
87 /// one of its (direct or indirect) bases. For example, given the
88 /// following class hierarchy:
89 ///
90 /// @code
91 /// class A { };
92 /// class B : public A { };
93 /// class C : public A { };
94 /// class D : public B, public C{ };
95 /// @endcode
96 ///
97 /// There are two potential BasePaths to represent paths from D to a
98 /// base subobject of type A. One path is (D,0) -> (B,0) -> (A,0)
99 /// and another is (D,0)->(C,0)->(A,1). These two paths actually
100 /// refer to two different base class subobjects of the same type,
101 /// so the BasePaths object refers to an ambiguous path. On the
102 /// other hand, consider the following class hierarchy:
103 ///
104 /// @code
105 /// class A { };
106 /// class B : public virtual A { };
107 /// class C : public virtual A { };
108 /// class D : public B, public C{ };
109 /// @endcode
110 ///
111 /// Here, there are two potential BasePaths again, (D, 0) -> (B, 0)
112 /// -> (A,v) and (D, 0) -> (C, 0) -> (A, v), but since both of them
113 /// refer to the same base class subobject of type A (the virtual
114 /// one), there is no ambiguity.
116  /// \brief The type from which this search originated.
117  CXXRecordDecl *Origin;
118 
119  /// Paths - The actual set of paths that can be taken from the
120  /// derived class to the same base class.
121  std::list<CXXBasePath> Paths;
122 
123  /// ClassSubobjects - Records the class subobjects for each class
124  /// type that we've seen. The first element in the pair says
125  /// whether we found a path to a virtual base for that class type,
126  /// while the element contains the number of non-virtual base
127  /// class subobjects for that class type. The key of the map is
128  /// the cv-unqualified canonical type of the base class subobject.
129  llvm::SmallDenseMap<QualType, std::pair<bool, unsigned>, 8> ClassSubobjects;
130 
131  /// VisitedDependentRecords - Records the dependent records that have been
132  /// already visited.
133  llvm::SmallDenseSet<const CXXRecordDecl *, 4> VisitedDependentRecords;
134 
135  /// FindAmbiguities - Whether Sema::IsDerivedFrom should try find
136  /// ambiguous paths while it is looking for a path from a derived
137  /// type to a base type.
138  bool FindAmbiguities;
139 
140  /// RecordPaths - Whether Sema::IsDerivedFrom should record paths
141  /// while it is determining whether there are paths from a derived
142  /// type to a base type.
143  bool RecordPaths;
144 
145  /// DetectVirtual - Whether Sema::IsDerivedFrom should abort the search
146  /// if it finds a path that goes across a virtual base. The virtual class
147  /// is also recorded.
148  bool DetectVirtual;
149 
150  /// ScratchPath - A BasePath that is used by Sema::lookupInBases
151  /// to help build the set of paths.
152  CXXBasePath ScratchPath;
153 
154  /// DetectedVirtual - The base class that is virtual.
155  const RecordType *DetectedVirtual;
156 
157  /// \brief Array of the declarations that have been found. This
158  /// array is constructed only if needed, e.g., to iterate over the
159  /// results within LookupResult.
160  std::unique_ptr<NamedDecl *[]> DeclsFound;
161  unsigned NumDeclsFound;
162 
163  friend class CXXRecordDecl;
164 
165  void ComputeDeclsFound();
166 
167  bool lookupInBases(ASTContext &Context, const CXXRecordDecl *Record,
169  bool LookupInDependent = false);
170 
171 public:
172  typedef std::list<CXXBasePath>::iterator paths_iterator;
173  typedef std::list<CXXBasePath>::const_iterator const_paths_iterator;
175 
176  /// BasePaths - Construct a new BasePaths structure to record the
177  /// paths for a derived-to-base search.
178  explicit CXXBasePaths(bool FindAmbiguities = true, bool RecordPaths = true,
179  bool DetectVirtual = true)
180  : Origin(), FindAmbiguities(FindAmbiguities), RecordPaths(RecordPaths),
181  DetectVirtual(DetectVirtual), DetectedVirtual(nullptr),
182  NumDeclsFound(0) {}
183 
184  paths_iterator begin() { return Paths.begin(); }
185  paths_iterator end() { return Paths.end(); }
186  const_paths_iterator begin() const { return Paths.begin(); }
187  const_paths_iterator end() const { return Paths.end(); }
188 
189  CXXBasePath& front() { return Paths.front(); }
190  const CXXBasePath& front() const { return Paths.front(); }
191 
192  typedef llvm::iterator_range<decl_iterator> decl_range;
193  decl_range found_decls();
194 
195  /// \brief Determine whether the path from the most-derived type to the
196  /// given base type is ambiguous (i.e., it refers to multiple subobjects of
197  /// the same base type).
198  bool isAmbiguous(CanQualType BaseType);
199 
200  /// \brief Whether we are finding multiple paths to detect ambiguities.
201  bool isFindingAmbiguities() const { return FindAmbiguities; }
202 
203  /// \brief Whether we are recording paths.
204  bool isRecordingPaths() const { return RecordPaths; }
205 
206  /// \brief Specify whether we should be recording paths or not.
207  void setRecordingPaths(bool RP) { RecordPaths = RP; }
208 
209  /// \brief Whether we are detecting virtual bases.
210  bool isDetectingVirtual() const { return DetectVirtual; }
211 
212  /// \brief The virtual base discovered on the path (if we are merely
213  /// detecting virtuals).
215  return DetectedVirtual;
216  }
217 
218  /// \brief Retrieve the type from which this base-paths search
219  /// began
220  CXXRecordDecl *getOrigin() const { return Origin; }
221  void setOrigin(CXXRecordDecl *Rec) { Origin = Rec; }
222 
223  /// \brief Clear the base-paths results.
224  void clear();
225 
226  /// \brief Swap this data structure's contents with another CXXBasePaths
227  /// object.
228  void swap(CXXBasePaths &Other);
229 };
230 
231 /// \brief Uniquely identifies a virtual method within a class
232 /// hierarchy by the method itself and a class subobject number.
235  : Method(nullptr), Subobject(0), InVirtualSubobject(nullptr) { }
236 
237  UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject,
238  const CXXRecordDecl *InVirtualSubobject)
239  : Method(Method), Subobject(Subobject),
240  InVirtualSubobject(InVirtualSubobject) { }
241 
242  /// \brief The overriding virtual method.
244 
245  /// \brief The subobject in which the overriding virtual method
246  /// resides.
247  unsigned Subobject;
248 
249  /// \brief The virtual base class subobject of which this overridden
250  /// virtual method is a part. Note that this records the closest
251  /// derived virtual base class subobject.
253 
254  friend bool operator==(const UniqueVirtualMethod &X,
255  const UniqueVirtualMethod &Y) {
256  return X.Method == Y.Method && X.Subobject == Y.Subobject &&
258  }
259 
260  friend bool operator!=(const UniqueVirtualMethod &X,
261  const UniqueVirtualMethod &Y) {
262  return !(X == Y);
263  }
264 };
265 
266 /// \brief The set of methods that override a given virtual method in
267 /// each subobject where it occurs.
268 ///
269 /// The first part of the pair is the subobject in which the
270 /// overridden virtual function occurs, while the second part of the
271 /// pair is the virtual method that overrides it (including the
272 /// subobject in which that virtual function occurs).
275  typedef llvm::MapVector<unsigned, ValuesT> MapType;
276  MapType Overrides;
277 
278 public:
279  // Iterate over the set of subobjects that have overriding methods.
280  typedef MapType::iterator iterator;
281  typedef MapType::const_iterator const_iterator;
282  iterator begin() { return Overrides.begin(); }
283  const_iterator begin() const { return Overrides.begin(); }
284  iterator end() { return Overrides.end(); }
285  const_iterator end() const { return Overrides.end(); }
286  unsigned size() const { return Overrides.size(); }
287 
288  // Iterate over the set of overriding virtual methods in a given
289  // subobject.
294 
295  // Add a new overriding method for a particular subobject.
296  void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding);
297 
298  // Add all of the overriding methods from "other" into overrides for
299  // this method. Used when merging the overrides from multiple base
300  // class subobjects.
301  void add(const OverridingMethods &Other);
302 
303  // Replace all overriding virtual methods in all subobjects with the
304  // given virtual method.
305  void replaceAll(UniqueVirtualMethod Overriding);
306 };
307 
308 /// \brief A mapping from each virtual member function to its set of
309 /// final overriders.
310 ///
311 /// Within a class hierarchy for a given derived class, each virtual
312 /// member function in that hierarchy has one or more "final
313 /// overriders" (C++ [class.virtual]p2). A final overrider for a
314 /// virtual function "f" is the virtual function that will actually be
315 /// invoked when dispatching a call to "f" through the
316 /// vtable. Well-formed classes have a single final overrider for each
317 /// virtual function; in abstract classes, the final overrider for at
318 /// least one virtual function is a pure virtual function. Due to
319 /// multiple, virtual inheritance, it is possible for a class to have
320 /// more than one final overrider. Athough this is an error (per C++
321 /// [class.virtual]p2), it is not considered an error here: the final
322 /// overrider map can represent multiple final overriders for a
323 /// method, and it is up to the client to determine whether they are
324 /// problem. For example, the following class \c D has two final
325 /// overriders for the virtual function \c A::f(), one in \c C and one
326 /// in \c D:
327 ///
328 /// \code
329 /// struct A { virtual void f(); };
330 /// struct B : virtual A { virtual void f(); };
331 /// struct C : virtual A { virtual void f(); };
332 /// struct D : B, C { };
333 /// \endcode
334 ///
335 /// This data structure contains a mapping from every virtual
336 /// function *that does not override an existing virtual function* and
337 /// in every subobject where that virtual function occurs to the set
338 /// of virtual functions that override it. Thus, the same virtual
339 /// function \c A::f can actually occur in multiple subobjects of type
340 /// \c A due to multiple inheritance, and may be overridden by
341 /// different virtual functions in each, as in the following example:
342 ///
343 /// \code
344 /// struct A { virtual void f(); };
345 /// struct B : A { virtual void f(); };
346 /// struct C : A { virtual void f(); };
347 /// struct D : B, C { };
348 /// \endcode
349 ///
350 /// Unlike in the previous example, where the virtual functions \c
351 /// B::f and \c C::f both overrode \c A::f in the same subobject of
352 /// type \c A, in this example the two virtual functions both override
353 /// \c A::f but in *different* subobjects of type A. This is
354 /// represented by numbering the subobjects in which the overridden
355 /// and the overriding virtual member functions are located. Subobject
356 /// 0 represents the virtual base class subobject of that type, while
357 /// subobject numbers greater than 0 refer to non-virtual base class
358 /// subobjects of that type.
360  : public llvm::MapVector<const CXXMethodDecl *, OverridingMethods> { };
361 
362 /// \brief A set of all the primary bases for a class.
364  : public llvm::SmallSet<const CXXRecordDecl*, 32> { };
365 
366 } // end namespace clang
367 
368 #endif
void setOrigin(CXXRecordDecl *Rec)
C Language Family Type Representation.
MapType::iterator iterator
virtual void clear()
AccessSpecifier
A C++ access specifier (public, private, protected), plus the special value "none" which means differ...
Definition: Specifiers.h:95
Represents a path from a specific derived class (which is not represented as part of the path) to a p...
DeclContext::lookup_result Decls
The set of declarations found inside this base class subobject.
MapType::const_iterator const_iterator
std::list< CXXBasePath >::const_iterator const_paths_iterator
bool isRecordingPaths() const
Whether we are recording paths.
friend bool operator!=(const UniqueVirtualMethod &X, const UniqueVirtualMethod &Y)
void setRecordingPaths(bool RP)
Specify whether we should be recording paths or not.
bool isFindingAmbiguities() const
Whether we are finding multiple paths to detect ambiguities.
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:128
The results of name lookup within a DeclContext.
Definition: DeclBase.h:1155
CXXMethodDecl * Method
The overriding virtual method.
The set of methods that override a given virtual method in each subobject where it occurs...
const_iterator end() const
llvm::function_ref< bool(const CXXBaseSpecifier *Specifier, CXXBasePath &Path)> BaseMatchesCallback
Function type used by lookupInBases() to determine whether a specific base class subobject matches th...
Definition: DeclCXX.h:1629
const RecordType * getDetectedVirtual() const
The virtual base discovered on the path (if we are merely detecting virtuals).
const_paths_iterator end() const
UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject, const CXXRecordDecl *InVirtualSubobject)
Allows QualTypes to be sorted and hence used in maps and sets.
NamedDecl ** decl_iterator
int SubobjectNumber
Identifies which base class subobject (of type Base->getType()) this base path element refers to...
Uniquely identifies a virtual method within a class hierarchy by the method itself and a class subobj...
const CXXBaseSpecifier * Base
The base specifier that states the link from a derived class to a base class, which will be followed ...
SmallVectorImpl< UniqueVirtualMethod >::const_iterator overriding_const_iterator
A set of all the primary bases for a class.
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1918
paths_iterator begin()
bool isDetectingVirtual() const
Whether we are detecting virtual bases.
const_paths_iterator begin() const
CXXRecordDecl * getOrigin() const
Retrieve the type from which this base-paths search began.
Represents an element in a path from a derived class to a base class.
const_iterator begin() const
Dataflow Directional Tag Classes.
SmallVectorImpl< UniqueVirtualMethod >::iterator overriding_iterator
unsigned Subobject
The subobject in which the overriding virtual method resides.
A mapping from each virtual member function to its set of final overriders.
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:3839
friend bool operator==(const UniqueVirtualMethod &X, const UniqueVirtualMethod &Y)
llvm::iterator_range< decl_iterator > decl_range
CXXBasePath & front()
Represents a base class of a C++ class.
Definition: DeclCXX.h:157
CXXBasePaths(bool FindAmbiguities=true, bool RecordPaths=true, bool DetectVirtual=true)
BasePaths - Construct a new BasePaths structure to record the paths for a derived-to-base search...
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:13160
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
Represents a C++ struct/union/class.
Definition: DeclCXX.h:266
AccessSpecifier Access
The access along this inheritance path.
const CXXBasePath & front() const
BasePaths - Represents the set of paths from a derived class to one of its (direct or indirect) bases...
const CXXRecordDecl * InVirtualSubobject
The virtual base class subobject of which this overridden virtual method is a part.
paths_iterator end()
NamedDecl - This represents a decl with a name.
Definition: Decl.h:213
const CXXRecordDecl * Class
The record decl of the class that the base is a base of.
std::list< CXXBasePath >::iterator paths_iterator