1 //===--- Lookup.h - Classes for name lookup ---------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the LookupResult class, which is integral to
11 // Sema's name-lookup subsystem.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_SEMA_LOOKUP_H
16 #define LLVM_CLANG_SEMA_LOOKUP_H
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/Sema/Sema.h"
23 /// @brief Represents the results of name lookup.
25 /// An instance of the LookupResult class captures the results of a
26 /// single name lookup, which can return no result (nothing found),
27 /// a single declaration, a set of overloaded functions, or an
28 /// ambiguity. Use the getKind() method to determine which of these
29 /// results occurred for a given lookup.
32 enum LookupResultKind {
33 /// @brief No entity found met the criteria.
36 /// @brief No entity found met the criteria within the current
37 /// instantiation,, but there were dependent base classes of the
38 /// current instantiation that could not be searched.
39 NotFoundInCurrentInstantiation,
41 /// @brief Name lookup found a single declaration that met the
42 /// criteria. getFoundDecl() will return this declaration.
45 /// @brief Name lookup found a set of overloaded functions that
49 /// @brief Name lookup found an unresolvable value declaration
50 /// and cannot yet complete. This only happens in C++ dependent
51 /// contexts with dependent using declarations.
54 /// @brief Name lookup results in an ambiguity; use
55 /// getAmbiguityKind to figure out what kind of ambiguity
61 /// Name lookup results in an ambiguity because multiple
62 /// entities that meet the lookup criteria were found in
63 /// subobjects of different types. For example:
65 /// struct A { void f(int); }
66 /// struct B { void f(double); }
67 /// struct C : A, B { };
69 /// c.f(0); // error: A::f and B::f come from subobjects of different
70 /// // types. overload resolution is not performed.
73 AmbiguousBaseSubobjectTypes,
75 /// Name lookup results in an ambiguity because multiple
76 /// nonstatic entities that meet the lookup criteria were found
77 /// in different subobjects of the same type. For example:
79 /// struct A { int x; };
82 /// struct D : B, C { };
84 /// return d.x; // error: 'x' is found in two A subobjects (of B and C)
87 AmbiguousBaseSubobjects,
89 /// Name lookup results in an ambiguity because multiple definitions
90 /// of entity that meet the lookup criteria were found in different
91 /// declaration contexts.
95 /// namespace B { int i; }
97 /// using namespace B;
98 /// return i; // error 'i' is found in namespace A and A::B
104 /// Name lookup results in an ambiguity because an entity with a
105 /// tag name was hidden by an entity with an ordinary name from
106 /// a different context.
108 /// namespace A { struct Foo {}; }
109 /// namespace B { void Foo(); }
111 /// using namespace A;
112 /// using namespace B;
115 /// C::Foo(); // error: tag 'A::Foo' is hidden by an object in a
116 /// // different namespace
122 /// A little identifier for flagging temporary lookup results.
123 enum TemporaryToken {
127 typedef UnresolvedSetImpl::iterator iterator;
129 LookupResult(Sema &SemaRef, const DeclarationNameInfo &NameInfo,
130 Sema::LookupNameKind LookupKind,
131 Sema::RedeclarationKind Redecl = Sema::NotForRedeclaration)
132 : ResultKind(NotFound),
134 NamingClass(nullptr),
137 LookupKind(LookupKind),
139 Redecl(Redecl != Sema::NotForRedeclaration),
141 Diagnose(Redecl == Sema::NotForRedeclaration),
142 AllowHidden(Redecl == Sema::ForRedeclaration),
148 // TODO: consider whether this constructor should be restricted to take
149 // as input a const IndentifierInfo* (instead of Name),
150 // forcing other cases towards the constructor taking a DNInfo.
151 LookupResult(Sema &SemaRef, DeclarationName Name,
152 SourceLocation NameLoc, Sema::LookupNameKind LookupKind,
153 Sema::RedeclarationKind Redecl = Sema::NotForRedeclaration)
154 : ResultKind(NotFound),
156 NamingClass(nullptr),
158 NameInfo(Name, NameLoc),
159 LookupKind(LookupKind),
161 Redecl(Redecl != Sema::NotForRedeclaration),
163 Diagnose(Redecl == Sema::NotForRedeclaration),
164 AllowHidden(Redecl == Sema::ForRedeclaration),
170 /// Creates a temporary lookup result, initializing its core data
171 /// using the information from another result. Diagnostics are always
173 LookupResult(TemporaryToken _, const LookupResult &Other)
174 : ResultKind(NotFound),
176 NamingClass(nullptr),
177 SemaPtr(Other.SemaPtr),
178 NameInfo(Other.NameInfo),
179 LookupKind(Other.LookupKind),
181 Redecl(Other.Redecl),
182 HideTags(Other.HideTags),
184 AllowHidden(Other.AllowHidden),
189 if (Diagnose) diagnose();
190 if (Paths) deletePaths(Paths);
193 /// Gets the name info to look up.
194 const DeclarationNameInfo &getLookupNameInfo() const {
198 /// \brief Sets the name info to look up.
199 void setLookupNameInfo(const DeclarationNameInfo &NameInfo) {
200 this->NameInfo = NameInfo;
203 /// Gets the name to look up.
204 DeclarationName getLookupName() const {
205 return NameInfo.getName();
208 /// \brief Sets the name to look up.
209 void setLookupName(DeclarationName Name) {
210 NameInfo.setName(Name);
213 /// Gets the kind of lookup to perform.
214 Sema::LookupNameKind getLookupKind() const {
218 /// True if this lookup is just looking for an existing declaration.
219 bool isForRedeclaration() const {
223 /// \brief Specify whether hidden declarations are visible, e.g.,
224 /// for recovery reasons.
225 void setAllowHidden(bool AH) {
229 /// \brief Determine whether this lookup is permitted to see hidden
230 /// declarations, such as those in modules that have not yet been imported.
231 bool isHiddenDeclarationVisible() const {
232 return AllowHidden || LookupKind == Sema::LookupTagName;
235 /// Sets whether tag declarations should be hidden by non-tag
236 /// declarations during resolution. The default is true.
237 void setHideTags(bool Hide) {
241 bool isAmbiguous() const {
242 return getResultKind() == Ambiguous;
245 /// Determines if this names a single result which is not an
246 /// unresolved value using decl. If so, it is safe to call
248 bool isSingleResult() const {
249 return getResultKind() == Found;
252 /// Determines if the results are overloaded.
253 bool isOverloadedResult() const {
254 return getResultKind() == FoundOverloaded;
257 bool isUnresolvableResult() const {
258 return getResultKind() == FoundUnresolvedValue;
261 LookupResultKind getResultKind() const {
266 AmbiguityKind getAmbiguityKind() const {
267 assert(isAmbiguous());
271 const UnresolvedSetImpl &asUnresolvedSet() const {
275 iterator begin() const { return iterator(Decls.begin()); }
276 iterator end() const { return iterator(Decls.end()); }
278 /// \brief Return true if no decls were found
279 bool empty() const { return Decls.empty(); }
281 /// \brief Return the base paths structure that's associated with
282 /// these results, or null if none is.
283 CXXBasePaths *getBasePaths() const {
287 /// \brief Determine whether the given declaration is visible to the
289 static bool isVisible(Sema &SemaRef, NamedDecl *D) {
290 // If this declaration is not hidden, it's visible.
294 // During template instantiation, we can refer to hidden declarations, if
295 // they were visible in any module along the path of instantiation.
296 return isVisibleSlow(SemaRef, D);
299 /// \brief Retrieve the accepted (re)declaration of the given declaration,
301 NamedDecl *getAcceptableDecl(NamedDecl *D) const {
302 if (!D->isInIdentifierNamespace(IDNS))
305 if (isVisible(getSema(), D))
308 if (auto *Visible = getAcceptableDeclSlow(D))
311 // Even if hidden declarations are visible, prefer a visible declaration.
312 return isHiddenDeclarationVisible() ? D : nullptr;
316 static bool isVisibleSlow(Sema &SemaRef, NamedDecl *D);
317 NamedDecl *getAcceptableDeclSlow(NamedDecl *D) const;
320 /// \brief Returns the identifier namespace mask for this lookup.
321 unsigned getIdentifierNamespace() const {
325 /// \brief Returns whether these results arose from performing a
326 /// lookup into a class.
327 bool isClassLookup() const {
328 return NamingClass != nullptr;
331 /// \brief Returns the 'naming class' for this lookup, i.e. the
332 /// class which was looked into to find these results.
334 /// C++0x [class.access.base]p5:
335 /// The access to a member is affected by the class in which the
336 /// member is named. This naming class is the class in which the
337 /// member name was looked up and found. [Note: this class can be
338 /// explicit, e.g., when a qualified-id is used, or implicit,
339 /// e.g., when a class member access operator (5.2.5) is used
340 /// (including cases where an implicit "this->" is added). If both
341 /// a class member access operator and a qualified-id are used to
342 /// name the member (as in p->T::m), the class naming the member
343 /// is the class named by the nested-name-specifier of the
344 /// qualified-id (that is, T). -- end note ]
346 /// This is set by the lookup routines when they find results in a class.
347 CXXRecordDecl *getNamingClass() const {
351 /// \brief Sets the 'naming class' for this lookup.
352 void setNamingClass(CXXRecordDecl *Record) {
353 NamingClass = Record;
356 /// \brief Returns the base object type associated with this lookup;
357 /// important for [class.protected]. Most lookups do not have an
358 /// associated base object.
359 QualType getBaseObjectType() const {
360 return BaseObjectType;
363 /// \brief Sets the base object type for this lookup.
364 void setBaseObjectType(QualType T) {
368 /// \brief Add a declaration to these results with its natural access.
369 /// Does not test the acceptance criteria.
370 void addDecl(NamedDecl *D) {
371 addDecl(D, D->getAccess());
374 /// \brief Add a declaration to these results with the given access.
375 /// Does not test the acceptance criteria.
376 void addDecl(NamedDecl *D, AccessSpecifier AS) {
377 Decls.addDecl(D, AS);
381 /// \brief Add all the declarations from another set of lookup
383 void addAllDecls(const LookupResult &Other) {
384 Decls.append(Other.Decls.begin(), Other.Decls.end());
388 /// \brief Determine whether no result was found because we could not
389 /// search into dependent base classes of the current instantiation.
390 bool wasNotFoundInCurrentInstantiation() const {
391 return ResultKind == NotFoundInCurrentInstantiation;
394 /// \brief Note that while no result was found in the current instantiation,
395 /// there were dependent base classes that could not be searched.
396 void setNotFoundInCurrentInstantiation() {
397 assert(ResultKind == NotFound && Decls.empty());
398 ResultKind = NotFoundInCurrentInstantiation;
401 /// \brief Determine whether the lookup result was shadowed by some other
402 /// declaration that lookup ignored.
403 bool isShadowed() const { return Shadowed; }
405 /// \brief Note that we found and ignored a declaration while performing
407 void setShadowed() { Shadowed = true; }
409 /// \brief Resolves the result kind of the lookup, possibly hiding
412 /// This should be called in any environment where lookup might
413 /// generate multiple lookup results.
416 /// \brief Re-resolves the result kind of the lookup after a set of
417 /// removals has been performed.
418 void resolveKindAfterFilter() {
420 if (ResultKind != NotFoundInCurrentInstantiation)
421 ResultKind = NotFound;
428 AmbiguityKind SavedAK;
429 bool WasAmbiguous = false;
430 if (ResultKind == Ambiguous) {
437 // If we didn't make the lookup unambiguous, restore the old
439 if (ResultKind == Ambiguous) {
441 assert(WasAmbiguous);
450 template <class DeclClass>
451 DeclClass *getAsSingle() const {
452 if (getResultKind() != Found) return nullptr;
453 return dyn_cast<DeclClass>(getFoundDecl());
456 /// \brief Fetch the unique decl found by this lookup. Asserts
457 /// that one was found.
459 /// This is intended for users who have examined the result kind
460 /// and are certain that there is only one result.
461 NamedDecl *getFoundDecl() const {
462 assert(getResultKind() == Found
463 && "getFoundDecl called on non-unique result");
464 return (*begin())->getUnderlyingDecl();
467 /// Fetches a representative decl. Useful for lazy diagnostics.
468 NamedDecl *getRepresentativeDecl() const {
469 assert(!Decls.empty() && "cannot get representative of empty set");
473 /// \brief Asks if the result is a single tag decl.
474 bool isSingleTagDecl() const {
475 return getResultKind() == Found && isa<TagDecl>(getFoundDecl());
478 /// \brief Make these results show that the name was found in
479 /// base classes of different types.
481 /// The given paths object is copied and invalidated.
482 void setAmbiguousBaseSubobjectTypes(CXXBasePaths &P);
484 /// \brief Make these results show that the name was found in
485 /// distinct base classes of the same type.
487 /// The given paths object is copied and invalidated.
488 void setAmbiguousBaseSubobjects(CXXBasePaths &P);
490 /// \brief Make these results show that the name was found in
491 /// different contexts and a tag decl was hidden by an ordinary
492 /// decl in a different context.
493 void setAmbiguousQualifiedTagHiding() {
494 setAmbiguous(AmbiguousTagHiding);
497 /// \brief Clears out any current state.
499 ResultKind = NotFound;
501 if (Paths) deletePaths(Paths);
503 NamingClass = nullptr;
507 /// \brief Clears out any current state and re-initializes for a
508 /// different kind of lookup.
509 void clear(Sema::LookupNameKind Kind) {
515 /// \brief Change this lookup's redeclaration kind.
516 void setRedeclarationKind(Sema::RedeclarationKind RK) {
518 AllowHidden = (RK == Sema::ForRedeclaration);
522 void print(raw_ostream &);
524 /// Suppress the diagnostics that would normally fire because of this
525 /// lookup. This happens during (e.g.) redeclaration lookups.
526 void suppressDiagnostics() {
530 /// Determines whether this lookup is suppressing diagnostics.
531 bool isSuppressingDiagnostics() const {
535 /// Sets a 'context' source range.
536 void setContextRange(SourceRange SR) {
537 NameContextRange = SR;
540 /// Gets the source range of the context of this name; for C++
541 /// qualified lookups, this is the source range of the scope
543 SourceRange getContextRange() const {
544 return NameContextRange;
547 /// Gets the location of the identifier. This isn't always defined:
548 /// sometimes we're doing lookups on synthesized names.
549 SourceLocation getNameLoc() const {
550 return NameInfo.getLoc();
553 /// \brief Get the Sema object that this lookup result is searching
555 Sema &getSema() const { return *SemaPtr; }
557 /// A class for iterating through a result set and possibly
558 /// filtering out results. The results returned are possibly
561 LookupResult &Results;
562 LookupResult::iterator I;
566 friend class LookupResult;
567 Filter(LookupResult &Results)
568 : Results(Results), I(Results.begin()), Changed(false), CalledDone(false)
574 "LookupResult::Filter destroyed without done() call");
577 bool hasNext() const {
578 return I != Results.end();
582 assert(I != Results.end() && "next() called on empty filter");
586 /// Restart the iteration.
591 /// Erase the last element returned from this iterator.
593 Results.Decls.erase(--I);
597 /// Replaces the current entry with the given one, preserving the
599 void replace(NamedDecl *D) {
600 Results.Decls.replace(I-1, D);
604 /// Replaces the current entry with the given one.
605 void replace(NamedDecl *D, AccessSpecifier AS) {
606 Results.Decls.replace(I-1, D, AS);
611 assert(!CalledDone && "done() called twice");
615 Results.resolveKindAfterFilter();
619 /// Create a filter for this result set.
620 Filter makeFilter() {
621 return Filter(*this);
624 void setFindLocalExtern(bool FindLocalExtern) {
626 IDNS |= Decl::IDNS_LocalExtern;
628 IDNS &= ~Decl::IDNS_LocalExtern;
634 getSema().DiagnoseAmbiguousLookup(*this);
635 else if (isClassLookup() && getSema().getLangOpts().AccessControl)
636 getSema().CheckLookupAccess(*this);
639 void setAmbiguous(AmbiguityKind AK) {
640 ResultKind = Ambiguous;
644 void addDeclsFromBasePaths(const CXXBasePaths &P);
650 bool sanityCheckUnresolved() const {
651 for (iterator I = begin(), E = end(); I != E; ++I)
652 if (isa<UnresolvedUsingValueDecl>((*I)->getUnderlyingDecl()))
657 static void deletePaths(CXXBasePaths *);
660 LookupResultKind ResultKind;
661 AmbiguityKind Ambiguity; // ill-defined unless ambiguous
662 UnresolvedSet<8> Decls;
664 CXXRecordDecl *NamingClass;
665 QualType BaseObjectType;
669 DeclarationNameInfo NameInfo;
670 SourceRange NameContextRange;
671 Sema::LookupNameKind LookupKind;
672 unsigned IDNS; // set by configure()
676 /// \brief True if tag declarations should be hidden if non-tags
682 /// \brief True if we should allow hidden declarations to be 'visible'.
685 /// \brief True if the found declarations were shadowed by some other
686 /// declaration that we skipped. This only happens when \c LookupKind
687 /// is \c LookupRedeclarationWithLinkage.
691 /// \brief Consumes visible declarations found when searching for
692 /// all visible names within a given scope or context.
694 /// This abstract class is meant to be subclassed by clients of \c
695 /// Sema::LookupVisibleDecls(), each of which should override the \c
696 /// FoundDecl() function to process declarations as they are found.
697 class VisibleDeclConsumer {
699 /// \brief Destroys the visible declaration consumer.
700 virtual ~VisibleDeclConsumer();
702 /// \brief Determine whether hidden declarations (from unimported
703 /// modules) should be given to this consumer. By default, they
704 /// are not included.
705 virtual bool includeHiddenDecls() const;
707 /// \brief Invoked each time \p Sema::LookupVisibleDecls() finds a
708 /// declaration visible from the current scope or context.
710 /// \param ND the declaration found.
712 /// \param Hiding a declaration that hides the declaration \p ND,
713 /// or NULL if no such declaration exists.
715 /// \param Ctx the original context from which the lookup started.
717 /// \param InBaseClass whether this declaration was found in base
718 /// class of the context we searched.
719 virtual void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, DeclContext *Ctx,
720 bool InBaseClass) = 0;
723 /// \brief A class for storing results from argument-dependent lookup.
726 /// A map from canonical decls to the 'most recent' decl.
727 llvm::DenseMap<NamedDecl*, NamedDecl*> Decls;
730 /// Adds a new ADL candidate to this map.
731 void insert(NamedDecl *D);
733 /// Removes any data associated with a given decl.
734 void erase(NamedDecl *D) {
735 Decls.erase(cast<NamedDecl>(D->getCanonicalDecl()));
739 : public llvm::iterator_adaptor_base<
740 iterator, llvm::DenseMap<NamedDecl *, NamedDecl *>::iterator,
741 std::forward_iterator_tag, NamedDecl *> {
742 friend class ADLResult;
744 iterator(llvm::DenseMap<NamedDecl *, NamedDecl *>::iterator Iter)
745 : iterator_adaptor_base(std::move(Iter)) {}
750 value_type operator*() const { return I->second; }
753 iterator begin() { return iterator(Decls.begin()); }
754 iterator end() { return iterator(Decls.end()); }