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 (isHiddenDeclarationVisible() || isVisible(getSema(), D))
308 return getAcceptableDeclSlow(D);
312 static bool isVisibleSlow(Sema &SemaRef, NamedDecl *D);
313 NamedDecl *getAcceptableDeclSlow(NamedDecl *D) const;
316 /// \brief Returns the identifier namespace mask for this lookup.
317 unsigned getIdentifierNamespace() const {
321 /// \brief Returns whether these results arose from performing a
322 /// lookup into a class.
323 bool isClassLookup() const {
324 return NamingClass != nullptr;
327 /// \brief Returns the 'naming class' for this lookup, i.e. the
328 /// class which was looked into to find these results.
330 /// C++0x [class.access.base]p5:
331 /// The access to a member is affected by the class in which the
332 /// member is named. This naming class is the class in which the
333 /// member name was looked up and found. [Note: this class can be
334 /// explicit, e.g., when a qualified-id is used, or implicit,
335 /// e.g., when a class member access operator (5.2.5) is used
336 /// (including cases where an implicit "this->" is added). If both
337 /// a class member access operator and a qualified-id are used to
338 /// name the member (as in p->T::m), the class naming the member
339 /// is the class named by the nested-name-specifier of the
340 /// qualified-id (that is, T). -- end note ]
342 /// This is set by the lookup routines when they find results in a class.
343 CXXRecordDecl *getNamingClass() const {
347 /// \brief Sets the 'naming class' for this lookup.
348 void setNamingClass(CXXRecordDecl *Record) {
349 NamingClass = Record;
352 /// \brief Returns the base object type associated with this lookup;
353 /// important for [class.protected]. Most lookups do not have an
354 /// associated base object.
355 QualType getBaseObjectType() const {
356 return BaseObjectType;
359 /// \brief Sets the base object type for this lookup.
360 void setBaseObjectType(QualType T) {
364 /// \brief Add a declaration to these results with its natural access.
365 /// Does not test the acceptance criteria.
366 void addDecl(NamedDecl *D) {
367 addDecl(D, D->getAccess());
370 /// \brief Add a declaration to these results with the given access.
371 /// Does not test the acceptance criteria.
372 void addDecl(NamedDecl *D, AccessSpecifier AS) {
373 Decls.addDecl(D, AS);
377 /// \brief Add all the declarations from another set of lookup
379 void addAllDecls(const LookupResult &Other) {
380 Decls.append(Other.Decls.begin(), Other.Decls.end());
384 /// \brief Determine whether no result was found because we could not
385 /// search into dependent base classes of the current instantiation.
386 bool wasNotFoundInCurrentInstantiation() const {
387 return ResultKind == NotFoundInCurrentInstantiation;
390 /// \brief Note that while no result was found in the current instantiation,
391 /// there were dependent base classes that could not be searched.
392 void setNotFoundInCurrentInstantiation() {
393 assert(ResultKind == NotFound && Decls.empty());
394 ResultKind = NotFoundInCurrentInstantiation;
397 /// \brief Determine whether the lookup result was shadowed by some other
398 /// declaration that lookup ignored.
399 bool isShadowed() const { return Shadowed; }
401 /// \brief Note that we found and ignored a declaration while performing
403 void setShadowed() { Shadowed = true; }
405 /// \brief Resolves the result kind of the lookup, possibly hiding
408 /// This should be called in any environment where lookup might
409 /// generate multiple lookup results.
412 /// \brief Re-resolves the result kind of the lookup after a set of
413 /// removals has been performed.
414 void resolveKindAfterFilter() {
416 if (ResultKind != NotFoundInCurrentInstantiation)
417 ResultKind = NotFound;
424 AmbiguityKind SavedAK;
425 bool WasAmbiguous = false;
426 if (ResultKind == Ambiguous) {
433 // If we didn't make the lookup unambiguous, restore the old
435 if (ResultKind == Ambiguous) {
437 assert(WasAmbiguous);
446 template <class DeclClass>
447 DeclClass *getAsSingle() const {
448 if (getResultKind() != Found) return nullptr;
449 return dyn_cast<DeclClass>(getFoundDecl());
452 /// \brief Fetch the unique decl found by this lookup. Asserts
453 /// that one was found.
455 /// This is intended for users who have examined the result kind
456 /// and are certain that there is only one result.
457 NamedDecl *getFoundDecl() const {
458 assert(getResultKind() == Found
459 && "getFoundDecl called on non-unique result");
460 return (*begin())->getUnderlyingDecl();
463 /// Fetches a representative decl. Useful for lazy diagnostics.
464 NamedDecl *getRepresentativeDecl() const {
465 assert(!Decls.empty() && "cannot get representative of empty set");
469 /// \brief Asks if the result is a single tag decl.
470 bool isSingleTagDecl() const {
471 return getResultKind() == Found && isa<TagDecl>(getFoundDecl());
474 /// \brief Make these results show that the name was found in
475 /// base classes of different types.
477 /// The given paths object is copied and invalidated.
478 void setAmbiguousBaseSubobjectTypes(CXXBasePaths &P);
480 /// \brief Make these results show that the name was found in
481 /// distinct base classes of the same type.
483 /// The given paths object is copied and invalidated.
484 void setAmbiguousBaseSubobjects(CXXBasePaths &P);
486 /// \brief Make these results show that the name was found in
487 /// different contexts and a tag decl was hidden by an ordinary
488 /// decl in a different context.
489 void setAmbiguousQualifiedTagHiding() {
490 setAmbiguous(AmbiguousTagHiding);
493 /// \brief Clears out any current state.
495 ResultKind = NotFound;
497 if (Paths) deletePaths(Paths);
499 NamingClass = nullptr;
503 /// \brief Clears out any current state and re-initializes for a
504 /// different kind of lookup.
505 void clear(Sema::LookupNameKind Kind) {
511 /// \brief Change this lookup's redeclaration kind.
512 void setRedeclarationKind(Sema::RedeclarationKind RK) {
514 AllowHidden = (RK == Sema::ForRedeclaration);
518 void print(raw_ostream &);
520 /// Suppress the diagnostics that would normally fire because of this
521 /// lookup. This happens during (e.g.) redeclaration lookups.
522 void suppressDiagnostics() {
526 /// Determines whether this lookup is suppressing diagnostics.
527 bool isSuppressingDiagnostics() const {
531 /// Sets a 'context' source range.
532 void setContextRange(SourceRange SR) {
533 NameContextRange = SR;
536 /// Gets the source range of the context of this name; for C++
537 /// qualified lookups, this is the source range of the scope
539 SourceRange getContextRange() const {
540 return NameContextRange;
543 /// Gets the location of the identifier. This isn't always defined:
544 /// sometimes we're doing lookups on synthesized names.
545 SourceLocation getNameLoc() const {
546 return NameInfo.getLoc();
549 /// \brief Get the Sema object that this lookup result is searching
551 Sema &getSema() const { return *SemaPtr; }
553 /// A class for iterating through a result set and possibly
554 /// filtering out results. The results returned are possibly
557 LookupResult &Results;
558 LookupResult::iterator I;
562 friend class LookupResult;
563 Filter(LookupResult &Results)
564 : Results(Results), I(Results.begin()), Changed(false), CalledDone(false)
570 "LookupResult::Filter destroyed without done() call");
573 bool hasNext() const {
574 return I != Results.end();
578 assert(I != Results.end() && "next() called on empty filter");
582 /// Restart the iteration.
587 /// Erase the last element returned from this iterator.
589 Results.Decls.erase(--I);
593 /// Replaces the current entry with the given one, preserving the
595 void replace(NamedDecl *D) {
596 Results.Decls.replace(I-1, D);
600 /// Replaces the current entry with the given one.
601 void replace(NamedDecl *D, AccessSpecifier AS) {
602 Results.Decls.replace(I-1, D, AS);
607 assert(!CalledDone && "done() called twice");
611 Results.resolveKindAfterFilter();
615 /// Create a filter for this result set.
616 Filter makeFilter() {
617 return Filter(*this);
620 void setFindLocalExtern(bool FindLocalExtern) {
622 IDNS |= Decl::IDNS_LocalExtern;
624 IDNS &= ~Decl::IDNS_LocalExtern;
630 getSema().DiagnoseAmbiguousLookup(*this);
631 else if (isClassLookup() && getSema().getLangOpts().AccessControl)
632 getSema().CheckLookupAccess(*this);
635 void setAmbiguous(AmbiguityKind AK) {
636 ResultKind = Ambiguous;
640 void addDeclsFromBasePaths(const CXXBasePaths &P);
646 bool sanityCheckUnresolved() const {
647 for (iterator I = begin(), E = end(); I != E; ++I)
648 if (isa<UnresolvedUsingValueDecl>((*I)->getUnderlyingDecl()))
653 static void deletePaths(CXXBasePaths *);
656 LookupResultKind ResultKind;
657 AmbiguityKind Ambiguity; // ill-defined unless ambiguous
658 UnresolvedSet<8> Decls;
660 CXXRecordDecl *NamingClass;
661 QualType BaseObjectType;
665 DeclarationNameInfo NameInfo;
666 SourceRange NameContextRange;
667 Sema::LookupNameKind LookupKind;
668 unsigned IDNS; // set by configure()
672 /// \brief True if tag declarations should be hidden if non-tags
678 /// \brief True if we should allow hidden declarations to be 'visible'.
681 /// \brief True if the found declarations were shadowed by some other
682 /// declaration that we skipped. This only happens when \c LookupKind
683 /// is \c LookupRedeclarationWithLinkage.
687 /// \brief Consumes visible declarations found when searching for
688 /// all visible names within a given scope or context.
690 /// This abstract class is meant to be subclassed by clients of \c
691 /// Sema::LookupVisibleDecls(), each of which should override the \c
692 /// FoundDecl() function to process declarations as they are found.
693 class VisibleDeclConsumer {
695 /// \brief Destroys the visible declaration consumer.
696 virtual ~VisibleDeclConsumer();
698 /// \brief Determine whether hidden declarations (from unimported
699 /// modules) should be given to this consumer. By default, they
700 /// are not included.
701 virtual bool includeHiddenDecls() const;
703 /// \brief Invoked each time \p Sema::LookupVisibleDecls() finds a
704 /// declaration visible from the current scope or context.
706 /// \param ND the declaration found.
708 /// \param Hiding a declaration that hides the declaration \p ND,
709 /// or NULL if no such declaration exists.
711 /// \param Ctx the original context from which the lookup started.
713 /// \param InBaseClass whether this declaration was found in base
714 /// class of the context we searched.
715 virtual void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, DeclContext *Ctx,
716 bool InBaseClass) = 0;
719 /// \brief A class for storing results from argument-dependent lookup.
722 /// A map from canonical decls to the 'most recent' decl.
723 llvm::DenseMap<NamedDecl*, NamedDecl*> Decls;
726 /// Adds a new ADL candidate to this map.
727 void insert(NamedDecl *D);
729 /// Removes any data associated with a given decl.
730 void erase(NamedDecl *D) {
731 Decls.erase(cast<NamedDecl>(D->getCanonicalDecl()));
735 : public llvm::iterator_adaptor_base<
736 iterator, llvm::DenseMap<NamedDecl *, NamedDecl *>::iterator,
737 std::forward_iterator_tag, NamedDecl *> {
738 friend class ADLResult;
740 iterator(llvm::DenseMap<NamedDecl *, NamedDecl *>::iterator Iter)
741 : iterator_adaptor_base(std::move(Iter)) {}
746 value_type operator*() const { return I->second; }
749 iterator begin() { return iterator(Decls.begin()); }
750 iterator end() { return iterator(Decls.end()); }