1//===--- SemaCXXScopeSpec.cpp - Semantic Analysis for C++ scope specifiers-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements C++ semantic analysis for scope specifiers.
10//
11//===----------------------------------------------------------------------===//
12
13#include "TypeLocBuilder.h"
14#include "clang/AST/ASTContext.h"
15#include "clang/AST/DeclTemplate.h"
16#include "clang/AST/ExprCXX.h"
17#include "clang/AST/NestedNameSpecifier.h"
18#include "clang/Basic/PartialDiagnostic.h"
19#include "clang/Sema/DeclSpec.h"
20#include "clang/Sema/Lookup.h"
21#include "clang/Sema/Template.h"
22#include "llvm/ADT/STLExtras.h"
23using namespace clang;
24
25/// Find the current instantiation that associated with the given type.
26static CXXRecordDecl *getCurrentInstantiationOf(QualType T,
27 DeclContext *CurContext) {
28 if (T.isNull())
29 return nullptr;
30
31 const Type *Ty = T->getCanonicalTypeInternal().getTypePtr();
32 if (const RecordType *RecordTy = dyn_cast<RecordType>(Val: Ty)) {
33 CXXRecordDecl *Record = cast<CXXRecordDecl>(Val: RecordTy->getDecl());
34 if (Record->isCurrentInstantiation(CurContext))
35 return Record;
36
37 return nullptr;
38 } else if (isa<InjectedClassNameType>(Val: Ty))
39 return cast<InjectedClassNameType>(Val: Ty)->getDecl();
40 else
41 return nullptr;
42}
43
44DeclContext *Sema::computeDeclContext(QualType T) {
45 if (!T->isDependentType())
46 if (const TagType *Tag = T->getAs<TagType>())
47 return Tag->getDecl();
48
49 return ::getCurrentInstantiationOf(T, CurContext);
50}
51
52DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
53 bool EnteringContext) {
54 if (!SS.isSet() || SS.isInvalid())
55 return nullptr;
56
57 NestedNameSpecifier *NNS = SS.getScopeRep();
58 if (NNS->isDependent()) {
59 // If this nested-name-specifier refers to the current
60 // instantiation, return its DeclContext.
61 if (CXXRecordDecl *Record = getCurrentInstantiationOf(NNS))
62 return Record;
63
64 if (EnteringContext) {
65 const Type *NNSType = NNS->getAsType();
66 if (!NNSType) {
67 return nullptr;
68 }
69
70 // Look through type alias templates, per C++0x [temp.dep.type]p1.
71 NNSType = Context.getCanonicalType(T: NNSType);
72 if (const auto *SpecType =
73 dyn_cast<TemplateSpecializationType>(Val: NNSType)) {
74 // We are entering the context of the nested name specifier, so try to
75 // match the nested name specifier to either a primary class template
76 // or a class template partial specialization.
77 if (ClassTemplateDecl *ClassTemplate =
78 dyn_cast_or_null<ClassTemplateDecl>(
79 Val: SpecType->getTemplateName().getAsTemplateDecl())) {
80 // FIXME: The fallback on the search of partial
81 // specialization using ContextType should be eventually removed since
82 // it doesn't handle the case of constrained template parameters
83 // correctly. Currently removing this fallback would change the
84 // diagnostic output for invalid code in a number of tests.
85 ClassTemplatePartialSpecializationDecl *PartialSpec = nullptr;
86 ArrayRef<TemplateParameterList *> TemplateParamLists =
87 SS.getTemplateParamLists();
88 if (!TemplateParamLists.empty()) {
89 unsigned Depth = ClassTemplate->getTemplateParameters()->getDepth();
90 auto L = find_if(Range&: TemplateParamLists,
91 P: [Depth](TemplateParameterList *TPL) {
92 return TPL->getDepth() == Depth;
93 });
94 if (L != TemplateParamLists.end()) {
95 void *Pos = nullptr;
96 PartialSpec = ClassTemplate->findPartialSpecialization(
97 Args: SpecType->template_arguments(), TPL: *L, InsertPos&: Pos);
98 }
99 } else {
100 PartialSpec =
101 ClassTemplate->findPartialSpecialization(T: QualType(SpecType, 0));
102 }
103
104 if (PartialSpec) {
105 // A declaration of the partial specialization must be visible.
106 // We can always recover here, because this only happens when we're
107 // entering the context, and that can't happen in a SFINAE context.
108 assert(!isSFINAEContext() && "partial specialization scope "
109 "specifier in SFINAE context?");
110 if (PartialSpec->hasDefinition() &&
111 !hasReachableDefinition(D: PartialSpec))
112 diagnoseMissingImport(Loc: SS.getLastQualifierNameLoc(), Decl: PartialSpec,
113 MIK: MissingImportKind::PartialSpecialization,
114 Recover: true);
115 return PartialSpec;
116 }
117
118 // If the type of the nested name specifier is the same as the
119 // injected class name of the named class template, we're entering
120 // into that class template definition.
121 QualType Injected =
122 ClassTemplate->getInjectedClassNameSpecialization();
123 if (Context.hasSameType(T1: Injected, T2: QualType(SpecType, 0)))
124 return ClassTemplate->getTemplatedDecl();
125 }
126 } else if (const RecordType *RecordT = NNSType->getAs<RecordType>()) {
127 // The nested name specifier refers to a member of a class template.
128 return RecordT->getDecl();
129 }
130 }
131
132 return nullptr;
133 }
134
135 switch (NNS->getKind()) {
136 case NestedNameSpecifier::Identifier:
137 llvm_unreachable("Dependent nested-name-specifier has no DeclContext");
138
139 case NestedNameSpecifier::Namespace:
140 return NNS->getAsNamespace();
141
142 case NestedNameSpecifier::NamespaceAlias:
143 return NNS->getAsNamespaceAlias()->getNamespace();
144
145 case NestedNameSpecifier::TypeSpec: {
146 const TagType *Tag = NNS->getAsType()->getAs<TagType>();
147 assert(Tag && "Non-tag type in nested-name-specifier");
148 return Tag->getDecl();
149 }
150
151 case NestedNameSpecifier::Global:
152 return Context.getTranslationUnitDecl();
153
154 case NestedNameSpecifier::Super:
155 return NNS->getAsRecordDecl();
156 }
157
158 llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
159}
160
161bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
162 if (!SS.isSet() || SS.isInvalid())
163 return false;
164
165 return SS.getScopeRep()->isDependent();
166}
167
168CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) {
169 assert(getLangOpts().CPlusPlus && "Only callable in C++");
170 assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed");
171
172 if (!NNS->getAsType())
173 return nullptr;
174
175 QualType T = QualType(NNS->getAsType(), 0);
176 return ::getCurrentInstantiationOf(T, CurContext);
177}
178
179/// Require that the context specified by SS be complete.
180///
181/// If SS refers to a type, this routine checks whether the type is
182/// complete enough (or can be made complete enough) for name lookup
183/// into the DeclContext. A type that is not yet completed can be
184/// considered "complete enough" if it is a class/struct/union/enum
185/// that is currently being defined. Or, if we have a type that names
186/// a class template specialization that is not a complete type, we
187/// will attempt to instantiate that class template.
188bool Sema::RequireCompleteDeclContext(CXXScopeSpec &SS,
189 DeclContext *DC) {
190 assert(DC && "given null context");
191
192 TagDecl *tag = dyn_cast<TagDecl>(Val: DC);
193
194 // If this is a dependent type, then we consider it complete.
195 // FIXME: This is wrong; we should require a (visible) definition to
196 // exist in this case too.
197 if (!tag || tag->isDependentContext())
198 return false;
199
200 // Grab the tag definition, if there is one.
201 QualType type = Context.getTypeDeclType(Decl: tag);
202 tag = type->getAsTagDecl();
203
204 // If we're currently defining this type, then lookup into the
205 // type is okay: don't complain that it isn't complete yet.
206 if (tag->isBeingDefined())
207 return false;
208
209 SourceLocation loc = SS.getLastQualifierNameLoc();
210 if (loc.isInvalid()) loc = SS.getRange().getBegin();
211
212 // The type must be complete.
213 if (RequireCompleteType(Loc: loc, T: type, DiagID: diag::err_incomplete_nested_name_spec,
214 Args: SS.getRange())) {
215 SS.SetInvalid(SS.getRange());
216 return true;
217 }
218
219 if (auto *EnumD = dyn_cast<EnumDecl>(Val: tag))
220 // Fixed enum types and scoped enum instantiations are complete, but they
221 // aren't valid as scopes until we see or instantiate their definition.
222 return RequireCompleteEnumDecl(D: EnumD, L: loc, SS: &SS);
223
224 return false;
225}
226
227/// Require that the EnumDecl is completed with its enumerators defined or
228/// instantiated. SS, if provided, is the ScopeRef parsed.
229///
230bool Sema::RequireCompleteEnumDecl(EnumDecl *EnumD, SourceLocation L,
231 CXXScopeSpec *SS) {
232 if (EnumD->isCompleteDefinition()) {
233 // If we know about the definition but it is not visible, complain.
234 NamedDecl *SuggestedDef = nullptr;
235 if (!hasReachableDefinition(D: EnumD, Suggested: &SuggestedDef,
236 /*OnlyNeedComplete*/ false)) {
237 // If the user is going to see an error here, recover by making the
238 // definition visible.
239 bool TreatAsComplete = !isSFINAEContext();
240 diagnoseMissingImport(Loc: L, Decl: SuggestedDef, MIK: MissingImportKind::Definition,
241 /*Recover*/ TreatAsComplete);
242 return !TreatAsComplete;
243 }
244 return false;
245 }
246
247 // Try to instantiate the definition, if this is a specialization of an
248 // enumeration temploid.
249 if (EnumDecl *Pattern = EnumD->getInstantiatedFromMemberEnum()) {
250 MemberSpecializationInfo *MSI = EnumD->getMemberSpecializationInfo();
251 if (MSI->getTemplateSpecializationKind() != TSK_ExplicitSpecialization) {
252 if (InstantiateEnum(PointOfInstantiation: L, Instantiation: EnumD, Pattern,
253 TemplateArgs: getTemplateInstantiationArgs(D: EnumD),
254 TSK: TSK_ImplicitInstantiation)) {
255 if (SS)
256 SS->SetInvalid(SS->getRange());
257 return true;
258 }
259 return false;
260 }
261 }
262
263 if (SS) {
264 Diag(Loc: L, DiagID: diag::err_incomplete_nested_name_spec)
265 << QualType(EnumD->getTypeForDecl(), 0) << SS->getRange();
266 SS->SetInvalid(SS->getRange());
267 } else {
268 Diag(Loc: L, DiagID: diag::err_incomplete_enum) << QualType(EnumD->getTypeForDecl(), 0);
269 Diag(Loc: EnumD->getLocation(), DiagID: diag::note_declared_at);
270 }
271
272 return true;
273}
274
275bool Sema::ActOnCXXGlobalScopeSpecifier(SourceLocation CCLoc,
276 CXXScopeSpec &SS) {
277 SS.MakeGlobal(Context, ColonColonLoc: CCLoc);
278 return false;
279}
280
281bool Sema::ActOnSuperScopeSpecifier(SourceLocation SuperLoc,
282 SourceLocation ColonColonLoc,
283 CXXScopeSpec &SS) {
284 if (getCurLambda()) {
285 Diag(Loc: SuperLoc, DiagID: diag::err_super_in_lambda_unsupported);
286 return true;
287 }
288
289 CXXRecordDecl *RD = nullptr;
290 for (Scope *S = getCurScope(); S; S = S->getParent()) {
291 if (S->isFunctionScope()) {
292 if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Val: S->getEntity()))
293 RD = MD->getParent();
294 break;
295 }
296 if (S->isClassScope()) {
297 RD = cast<CXXRecordDecl>(Val: S->getEntity());
298 break;
299 }
300 }
301
302 if (!RD) {
303 Diag(Loc: SuperLoc, DiagID: diag::err_invalid_super_scope);
304 return true;
305 } else if (RD->getNumBases() == 0) {
306 Diag(Loc: SuperLoc, DiagID: diag::err_no_base_classes) << RD->getName();
307 return true;
308 }
309
310 SS.MakeSuper(Context, RD, SuperLoc, ColonColonLoc);
311 return false;
312}
313
314bool Sema::isAcceptableNestedNameSpecifier(const NamedDecl *SD,
315 bool *IsExtension) {
316 if (!SD)
317 return false;
318
319 SD = SD->getUnderlyingDecl();
320
321 // Namespace and namespace aliases are fine.
322 if (isa<NamespaceDecl>(Val: SD))
323 return true;
324
325 if (!isa<TypeDecl>(Val: SD))
326 return false;
327
328 // Determine whether we have a class (or, in C++11, an enum) or
329 // a typedef thereof. If so, build the nested-name-specifier.
330 QualType T = Context.getTypeDeclType(Decl: cast<TypeDecl>(Val: SD));
331 if (T->isDependentType())
332 return true;
333 if (const TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(Val: SD)) {
334 if (TD->getUnderlyingType()->isRecordType())
335 return true;
336 if (TD->getUnderlyingType()->isEnumeralType()) {
337 if (Context.getLangOpts().CPlusPlus11)
338 return true;
339 if (IsExtension)
340 *IsExtension = true;
341 }
342 } else if (isa<RecordDecl>(Val: SD)) {
343 return true;
344 } else if (isa<EnumDecl>(Val: SD)) {
345 if (Context.getLangOpts().CPlusPlus11)
346 return true;
347 if (IsExtension)
348 *IsExtension = true;
349 }
350
351 return false;
352}
353
354NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) {
355 if (!S || !NNS)
356 return nullptr;
357
358 while (NNS->getPrefix())
359 NNS = NNS->getPrefix();
360
361 if (NNS->getKind() != NestedNameSpecifier::Identifier)
362 return nullptr;
363
364 LookupResult Found(*this, NNS->getAsIdentifier(), SourceLocation(),
365 LookupNestedNameSpecifierName);
366 LookupName(R&: Found, S);
367 assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
368
369 if (!Found.isSingleResult())
370 return nullptr;
371
372 NamedDecl *Result = Found.getFoundDecl();
373 if (isAcceptableNestedNameSpecifier(SD: Result))
374 return Result;
375
376 return nullptr;
377}
378
379namespace {
380
381// Callback to only accept typo corrections that can be a valid C++ member
382// initializer: either a non-static field member or a base class.
383class NestedNameSpecifierValidatorCCC final
384 : public CorrectionCandidateCallback {
385public:
386 explicit NestedNameSpecifierValidatorCCC(Sema &SRef)
387 : SRef(SRef) {}
388
389 bool ValidateCandidate(const TypoCorrection &candidate) override {
390 return SRef.isAcceptableNestedNameSpecifier(SD: candidate.getCorrectionDecl());
391 }
392
393 std::unique_ptr<CorrectionCandidateCallback> clone() override {
394 return std::make_unique<NestedNameSpecifierValidatorCCC>(args&: *this);
395 }
396
397 private:
398 Sema &SRef;
399};
400
401}
402
403bool Sema::BuildCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
404 bool EnteringContext, CXXScopeSpec &SS,
405 NamedDecl *ScopeLookupResult,
406 bool ErrorRecoveryLookup,
407 bool *IsCorrectedToColon,
408 bool OnlyNamespace) {
409 if (IdInfo.Identifier->isEditorPlaceholder())
410 return true;
411 LookupResult Found(*this, IdInfo.Identifier, IdInfo.IdentifierLoc,
412 OnlyNamespace ? LookupNamespaceName
413 : LookupNestedNameSpecifierName);
414 QualType ObjectType = GetTypeFromParser(Ty: IdInfo.ObjectType);
415
416 // Determine where to perform name lookup
417 DeclContext *LookupCtx = nullptr;
418 bool isDependent = false;
419 if (IsCorrectedToColon)
420 *IsCorrectedToColon = false;
421 if (!ObjectType.isNull()) {
422 // This nested-name-specifier occurs in a member access expression, e.g.,
423 // x->B::f, and we are looking into the type of the object.
424 assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
425 LookupCtx = computeDeclContext(T: ObjectType);
426 isDependent = ObjectType->isDependentType();
427 } else if (SS.isSet()) {
428 // This nested-name-specifier occurs after another nested-name-specifier,
429 // so look into the context associated with the prior nested-name-specifier.
430 LookupCtx = computeDeclContext(SS, EnteringContext);
431 isDependent = isDependentScopeSpecifier(SS);
432 Found.setContextRange(SS.getRange());
433 }
434
435 bool ObjectTypeSearchedInScope = false;
436 if (LookupCtx) {
437 // Perform "qualified" name lookup into the declaration context we
438 // computed, which is either the type of the base of a member access
439 // expression or the declaration context associated with a prior
440 // nested-name-specifier.
441
442 // The declaration context must be complete.
443 if (!LookupCtx->isDependentContext() &&
444 RequireCompleteDeclContext(SS, DC: LookupCtx))
445 return true;
446
447 LookupQualifiedName(R&: Found, LookupCtx);
448
449 if (!ObjectType.isNull() && Found.empty()) {
450 // C++ [basic.lookup.classref]p4:
451 // If the id-expression in a class member access is a qualified-id of
452 // the form
453 //
454 // class-name-or-namespace-name::...
455 //
456 // the class-name-or-namespace-name following the . or -> operator is
457 // looked up both in the context of the entire postfix-expression and in
458 // the scope of the class of the object expression. If the name is found
459 // only in the scope of the class of the object expression, the name
460 // shall refer to a class-name. If the name is found only in the
461 // context of the entire postfix-expression, the name shall refer to a
462 // class-name or namespace-name. [...]
463 //
464 // Qualified name lookup into a class will not find a namespace-name,
465 // so we do not need to diagnose that case specifically. However,
466 // this qualified name lookup may find nothing. In that case, perform
467 // unqualified name lookup in the given scope (if available) or
468 // reconstruct the result from when name lookup was performed at template
469 // definition time.
470 if (S)
471 LookupName(R&: Found, S);
472 else if (ScopeLookupResult)
473 Found.addDecl(D: ScopeLookupResult);
474
475 ObjectTypeSearchedInScope = true;
476 }
477 } else if (!isDependent) {
478 // Perform unqualified name lookup in the current scope.
479 LookupName(R&: Found, S);
480 }
481
482 if (Found.isAmbiguous())
483 return true;
484
485 // If we performed lookup into a dependent context and did not find anything,
486 // that's fine: just build a dependent nested-name-specifier.
487 if (Found.empty() && isDependent &&
488 !(LookupCtx && LookupCtx->isRecord() &&
489 (!cast<CXXRecordDecl>(Val: LookupCtx)->hasDefinition() ||
490 !cast<CXXRecordDecl>(Val: LookupCtx)->hasAnyDependentBases()))) {
491 // Don't speculate if we're just trying to improve error recovery.
492 if (ErrorRecoveryLookup)
493 return true;
494
495 // We were not able to compute the declaration context for a dependent
496 // base object type or prior nested-name-specifier, so this
497 // nested-name-specifier refers to an unknown specialization. Just build
498 // a dependent nested-name-specifier.
499 SS.Extend(Context, Identifier: IdInfo.Identifier, IdentifierLoc: IdInfo.IdentifierLoc, ColonColonLoc: IdInfo.CCLoc);
500 return false;
501 }
502
503 if (Found.empty() && !ErrorRecoveryLookup) {
504 // If identifier is not found as class-name-or-namespace-name, but is found
505 // as other entity, don't look for typos.
506 LookupResult R(*this, Found.getLookupNameInfo(), LookupOrdinaryName);
507 if (LookupCtx)
508 LookupQualifiedName(R, LookupCtx);
509 else if (S && !isDependent)
510 LookupName(R, S);
511 if (!R.empty()) {
512 // Don't diagnose problems with this speculative lookup.
513 R.suppressDiagnostics();
514 // The identifier is found in ordinary lookup. If correction to colon is
515 // allowed, suggest replacement to ':'.
516 if (IsCorrectedToColon) {
517 *IsCorrectedToColon = true;
518 Diag(Loc: IdInfo.CCLoc, DiagID: diag::err_nested_name_spec_is_not_class)
519 << IdInfo.Identifier << getLangOpts().CPlusPlus
520 << FixItHint::CreateReplacement(RemoveRange: IdInfo.CCLoc, Code: ":");
521 if (NamedDecl *ND = R.getAsSingle<NamedDecl>())
522 Diag(Loc: ND->getLocation(), DiagID: diag::note_declared_at);
523 return true;
524 }
525 // Replacement '::' -> ':' is not allowed, just issue respective error.
526 Diag(Loc: R.getNameLoc(), DiagID: OnlyNamespace
527 ? unsigned(diag::err_expected_namespace_name)
528 : unsigned(diag::err_expected_class_or_namespace))
529 << IdInfo.Identifier << getLangOpts().CPlusPlus;
530 if (NamedDecl *ND = R.getAsSingle<NamedDecl>())
531 Diag(Loc: ND->getLocation(), DiagID: diag::note_entity_declared_at)
532 << IdInfo.Identifier;
533 return true;
534 }
535 }
536
537 if (Found.empty() && !ErrorRecoveryLookup && !getLangOpts().MSVCCompat) {
538 // We haven't found anything, and we're not recovering from a
539 // different kind of error, so look for typos.
540 DeclarationName Name = Found.getLookupName();
541 Found.clear();
542 NestedNameSpecifierValidatorCCC CCC(*this);
543 if (TypoCorrection Corrected = CorrectTypo(
544 Typo: Found.getLookupNameInfo(), LookupKind: Found.getLookupKind(), S, SS: &SS, CCC,
545 Mode: CorrectTypoKind::ErrorRecovery, MemberContext: LookupCtx, EnteringContext)) {
546 if (LookupCtx) {
547 bool DroppedSpecifier =
548 Corrected.WillReplaceSpecifier() &&
549 Name.getAsString() == Corrected.getAsString(LO: getLangOpts());
550 if (DroppedSpecifier)
551 SS.clear();
552 diagnoseTypo(Correction: Corrected, TypoDiag: PDiag(DiagID: diag::err_no_member_suggest)
553 << Name << LookupCtx << DroppedSpecifier
554 << SS.getRange());
555 } else
556 diagnoseTypo(Correction: Corrected, TypoDiag: PDiag(DiagID: diag::err_undeclared_var_use_suggest)
557 << Name);
558
559 if (Corrected.getCorrectionSpecifier())
560 SS.MakeTrivial(Context, Qualifier: Corrected.getCorrectionSpecifier(),
561 R: SourceRange(Found.getNameLoc()));
562
563 if (NamedDecl *ND = Corrected.getFoundDecl())
564 Found.addDecl(D: ND);
565 Found.setLookupName(Corrected.getCorrection());
566 } else {
567 Found.setLookupName(IdInfo.Identifier);
568 }
569 }
570
571 NamedDecl *SD =
572 Found.isSingleResult() ? Found.getRepresentativeDecl() : nullptr;
573 bool IsExtension = false;
574 bool AcceptSpec = isAcceptableNestedNameSpecifier(SD, IsExtension: &IsExtension);
575 if (!AcceptSpec && IsExtension) {
576 AcceptSpec = true;
577 Diag(Loc: IdInfo.IdentifierLoc, DiagID: diag::ext_nested_name_spec_is_enum);
578 }
579 if (AcceptSpec) {
580 if (!ObjectType.isNull() && !ObjectTypeSearchedInScope &&
581 !getLangOpts().CPlusPlus11) {
582 // C++03 [basic.lookup.classref]p4:
583 // [...] If the name is found in both contexts, the
584 // class-name-or-namespace-name shall refer to the same entity.
585 //
586 // We already found the name in the scope of the object. Now, look
587 // into the current scope (the scope of the postfix-expression) to
588 // see if we can find the same name there. As above, if there is no
589 // scope, reconstruct the result from the template instantiation itself.
590 //
591 // Note that C++11 does *not* perform this redundant lookup.
592 NamedDecl *OuterDecl;
593 if (S) {
594 LookupResult FoundOuter(*this, IdInfo.Identifier, IdInfo.IdentifierLoc,
595 LookupNestedNameSpecifierName);
596 LookupName(R&: FoundOuter, S);
597 OuterDecl = FoundOuter.getAsSingle<NamedDecl>();
598 } else
599 OuterDecl = ScopeLookupResult;
600
601 if (isAcceptableNestedNameSpecifier(SD: OuterDecl) &&
602 OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
603 (!isa<TypeDecl>(Val: OuterDecl) || !isa<TypeDecl>(Val: SD) ||
604 !Context.hasSameType(
605 T1: Context.getTypeDeclType(Decl: cast<TypeDecl>(Val: OuterDecl)),
606 T2: Context.getTypeDeclType(Decl: cast<TypeDecl>(Val: SD))))) {
607 if (ErrorRecoveryLookup)
608 return true;
609
610 Diag(Loc: IdInfo.IdentifierLoc,
611 DiagID: diag::err_nested_name_member_ref_lookup_ambiguous)
612 << IdInfo.Identifier;
613 Diag(Loc: SD->getLocation(), DiagID: diag::note_ambig_member_ref_object_type)
614 << ObjectType;
615 Diag(Loc: OuterDecl->getLocation(), DiagID: diag::note_ambig_member_ref_scope);
616
617 // Fall through so that we'll pick the name we found in the object
618 // type, since that's probably what the user wanted anyway.
619 }
620 }
621
622 if (auto *TD = dyn_cast_or_null<TypedefNameDecl>(Val: SD))
623 MarkAnyDeclReferenced(Loc: TD->getLocation(), D: TD, /*OdrUse=*/MightBeOdrUse: false);
624
625 // If we're just performing this lookup for error-recovery purposes,
626 // don't extend the nested-name-specifier. Just return now.
627 if (ErrorRecoveryLookup)
628 return false;
629
630 // The use of a nested name specifier may trigger deprecation warnings.
631 DiagnoseUseOfDecl(D: SD, Locs: IdInfo.CCLoc);
632
633 if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(Val: SD)) {
634 SS.Extend(Context, Namespace, NamespaceLoc: IdInfo.IdentifierLoc, ColonColonLoc: IdInfo.CCLoc);
635 return false;
636 }
637
638 if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(Val: SD)) {
639 SS.Extend(Context, Alias, AliasLoc: IdInfo.IdentifierLoc, ColonColonLoc: IdInfo.CCLoc);
640 return false;
641 }
642
643 QualType T =
644 Context.getTypeDeclType(Decl: cast<TypeDecl>(Val: SD->getUnderlyingDecl()));
645
646 if (T->isEnumeralType())
647 Diag(Loc: IdInfo.IdentifierLoc, DiagID: diag::warn_cxx98_compat_enum_nested_name_spec);
648
649 TypeLocBuilder TLB;
650 if (const auto *USD = dyn_cast<UsingShadowDecl>(Val: SD)) {
651 T = Context.getUsingType(Found: USD, Underlying: T);
652 TLB.pushTypeSpec(T).setNameLoc(IdInfo.IdentifierLoc);
653 } else if (isa<InjectedClassNameType>(Val: T)) {
654 InjectedClassNameTypeLoc InjectedTL
655 = TLB.push<InjectedClassNameTypeLoc>(T);
656 InjectedTL.setNameLoc(IdInfo.IdentifierLoc);
657 } else if (isa<RecordType>(Val: T)) {
658 RecordTypeLoc RecordTL = TLB.push<RecordTypeLoc>(T);
659 RecordTL.setNameLoc(IdInfo.IdentifierLoc);
660 } else if (isa<TypedefType>(Val: T)) {
661 TypedefTypeLoc TypedefTL = TLB.push<TypedefTypeLoc>(T);
662 TypedefTL.setNameLoc(IdInfo.IdentifierLoc);
663 } else if (isa<EnumType>(Val: T)) {
664 EnumTypeLoc EnumTL = TLB.push<EnumTypeLoc>(T);
665 EnumTL.setNameLoc(IdInfo.IdentifierLoc);
666 } else if (isa<TemplateTypeParmType>(Val: T)) {
667 TemplateTypeParmTypeLoc TemplateTypeTL
668 = TLB.push<TemplateTypeParmTypeLoc>(T);
669 TemplateTypeTL.setNameLoc(IdInfo.IdentifierLoc);
670 } else if (isa<UnresolvedUsingType>(Val: T)) {
671 UnresolvedUsingTypeLoc UnresolvedTL
672 = TLB.push<UnresolvedUsingTypeLoc>(T);
673 UnresolvedTL.setNameLoc(IdInfo.IdentifierLoc);
674 } else if (isa<SubstTemplateTypeParmType>(Val: T)) {
675 SubstTemplateTypeParmTypeLoc TL
676 = TLB.push<SubstTemplateTypeParmTypeLoc>(T);
677 TL.setNameLoc(IdInfo.IdentifierLoc);
678 } else if (isa<SubstTemplateTypeParmPackType>(Val: T)) {
679 SubstTemplateTypeParmPackTypeLoc TL
680 = TLB.push<SubstTemplateTypeParmPackTypeLoc>(T);
681 TL.setNameLoc(IdInfo.IdentifierLoc);
682 } else {
683 llvm_unreachable("Unhandled TypeDecl node in nested-name-specifier");
684 }
685
686 SS.Extend(Context, TL: TLB.getTypeLocInContext(Context, T), ColonColonLoc: IdInfo.CCLoc);
687 return false;
688 }
689
690 // Otherwise, we have an error case. If we don't want diagnostics, just
691 // return an error now.
692 if (ErrorRecoveryLookup)
693 return true;
694
695 // If we didn't find anything during our lookup, try again with
696 // ordinary name lookup, which can help us produce better error
697 // messages.
698 if (Found.empty()) {
699 Found.clear(Kind: LookupOrdinaryName);
700 LookupName(R&: Found, S);
701 }
702
703 // In Microsoft mode, if we are within a templated function and we can't
704 // resolve Identifier, then extend the SS with Identifier. This will have
705 // the effect of resolving Identifier during template instantiation.
706 // The goal is to be able to resolve a function call whose
707 // nested-name-specifier is located inside a dependent base class.
708 // Example:
709 //
710 // class C {
711 // public:
712 // static void foo2() { }
713 // };
714 // template <class T> class A { public: typedef C D; };
715 //
716 // template <class T> class B : public A<T> {
717 // public:
718 // void foo() { D::foo2(); }
719 // };
720 if (getLangOpts().MSVCCompat) {
721 DeclContext *DC = LookupCtx ? LookupCtx : CurContext;
722 if (DC->isDependentContext() && DC->isFunctionOrMethod()) {
723 CXXRecordDecl *ContainingClass = dyn_cast<CXXRecordDecl>(Val: DC->getParent());
724 if (ContainingClass && ContainingClass->hasAnyDependentBases()) {
725 Diag(Loc: IdInfo.IdentifierLoc,
726 DiagID: diag::ext_undeclared_unqual_id_with_dependent_base)
727 << IdInfo.Identifier << ContainingClass;
728 // Fake up a nested-name-specifier that starts with the
729 // injected-class-name of the enclosing class.
730 QualType T = Context.getTypeDeclType(Decl: ContainingClass);
731 TypeLocBuilder TLB;
732 TLB.pushTrivial(Context, T, Loc: IdInfo.IdentifierLoc);
733 SS.Extend(Context, TL: TLB.getTypeLocInContext(Context, T),
734 ColonColonLoc: IdInfo.IdentifierLoc);
735 // Add the identifier to form a dependent name.
736 SS.Extend(Context, Identifier: IdInfo.Identifier, IdentifierLoc: IdInfo.IdentifierLoc,
737 ColonColonLoc: IdInfo.CCLoc);
738 return false;
739 }
740 }
741 }
742
743 if (!Found.empty()) {
744 if (TypeDecl *TD = Found.getAsSingle<TypeDecl>()) {
745 Diag(Loc: IdInfo.IdentifierLoc, DiagID: diag::err_expected_class_or_namespace)
746 << Context.getTypeDeclType(Decl: TD) << getLangOpts().CPlusPlus;
747 } else if (Found.getAsSingle<TemplateDecl>()) {
748 ParsedType SuggestedType;
749 DiagnoseUnknownTypeName(II&: IdInfo.Identifier, IILoc: IdInfo.IdentifierLoc, S, SS: &SS,
750 SuggestedType);
751 } else {
752 Diag(Loc: IdInfo.IdentifierLoc, DiagID: diag::err_expected_class_or_namespace)
753 << IdInfo.Identifier << getLangOpts().CPlusPlus;
754 if (NamedDecl *ND = Found.getAsSingle<NamedDecl>())
755 Diag(Loc: ND->getLocation(), DiagID: diag::note_entity_declared_at)
756 << IdInfo.Identifier;
757 }
758 } else if (SS.isSet())
759 Diag(Loc: IdInfo.IdentifierLoc, DiagID: diag::err_no_member) << IdInfo.Identifier
760 << LookupCtx << SS.getRange();
761 else
762 Diag(Loc: IdInfo.IdentifierLoc, DiagID: diag::err_undeclared_var_use)
763 << IdInfo.Identifier;
764
765 return true;
766}
767
768bool Sema::ActOnCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
769 bool EnteringContext, CXXScopeSpec &SS,
770 bool *IsCorrectedToColon,
771 bool OnlyNamespace) {
772 if (SS.isInvalid())
773 return true;
774
775 return BuildCXXNestedNameSpecifier(S, IdInfo, EnteringContext, SS,
776 /*ScopeLookupResult=*/nullptr, ErrorRecoveryLookup: false,
777 IsCorrectedToColon, OnlyNamespace);
778}
779
780bool Sema::ActOnCXXNestedNameSpecifierDecltype(CXXScopeSpec &SS,
781 const DeclSpec &DS,
782 SourceLocation ColonColonLoc) {
783 if (SS.isInvalid() || DS.getTypeSpecType() == DeclSpec::TST_error)
784 return true;
785
786 assert(DS.getTypeSpecType() == DeclSpec::TST_decltype);
787
788 QualType T = BuildDecltypeType(E: DS.getRepAsExpr());
789 if (T.isNull())
790 return true;
791
792 if (!T->isDependentType() && !T->getAs<TagType>()) {
793 Diag(Loc: DS.getTypeSpecTypeLoc(), DiagID: diag::err_expected_class_or_namespace)
794 << T << getLangOpts().CPlusPlus;
795 return true;
796 }
797
798 TypeLocBuilder TLB;
799 DecltypeTypeLoc DecltypeTL = TLB.push<DecltypeTypeLoc>(T);
800 DecltypeTL.setDecltypeLoc(DS.getTypeSpecTypeLoc());
801 DecltypeTL.setRParenLoc(DS.getTypeofParensRange().getEnd());
802 SS.Extend(Context, TL: TLB.getTypeLocInContext(Context, T), ColonColonLoc);
803 return false;
804}
805
806bool Sema::ActOnCXXNestedNameSpecifierIndexedPack(CXXScopeSpec &SS,
807 const DeclSpec &DS,
808 SourceLocation ColonColonLoc,
809 QualType Type) {
810 if (SS.isInvalid() || DS.getTypeSpecType() == DeclSpec::TST_error)
811 return true;
812
813 assert(DS.getTypeSpecType() == DeclSpec::TST_typename_pack_indexing);
814
815 if (Type.isNull())
816 return true;
817
818 TypeLocBuilder TLB;
819 TLB.pushTrivial(Context&: getASTContext(),
820 T: cast<PackIndexingType>(Val: Type.getTypePtr())->getPattern(),
821 Loc: DS.getBeginLoc());
822 PackIndexingTypeLoc PIT = TLB.push<PackIndexingTypeLoc>(T: Type);
823 PIT.setEllipsisLoc(DS.getEllipsisLoc());
824 SS.Extend(Context, TL: TLB.getTypeLocInContext(Context, T: Type), ColonColonLoc);
825 return false;
826}
827
828bool Sema::IsInvalidUnlessNestedName(Scope *S, CXXScopeSpec &SS,
829 NestedNameSpecInfo &IdInfo,
830 bool EnteringContext) {
831 if (SS.isInvalid())
832 return false;
833
834 return !BuildCXXNestedNameSpecifier(S, IdInfo, EnteringContext, SS,
835 /*ScopeLookupResult=*/nullptr, ErrorRecoveryLookup: true);
836}
837
838bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
839 CXXScopeSpec &SS,
840 SourceLocation TemplateKWLoc,
841 TemplateTy OpaqueTemplate,
842 SourceLocation TemplateNameLoc,
843 SourceLocation LAngleLoc,
844 ASTTemplateArgsPtr TemplateArgsIn,
845 SourceLocation RAngleLoc,
846 SourceLocation CCLoc,
847 bool EnteringContext) {
848 if (SS.isInvalid())
849 return true;
850
851 TemplateName Template = OpaqueTemplate.get();
852
853 // Translate the parser's template argument list in our AST format.
854 TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
855 translateTemplateArguments(In: TemplateArgsIn, Out&: TemplateArgs);
856
857 DependentTemplateName *DTN = Template.getAsDependentTemplateName();
858 if (DTN && DTN->getName().getIdentifier()) {
859 // Handle a dependent template specialization for which we cannot resolve
860 // the template name.
861 assert(DTN->getQualifier() == SS.getScopeRep());
862 QualType T = Context.getDependentTemplateSpecializationType(
863 Keyword: ElaboratedTypeKeyword::None,
864 Name: {/*Qualifier=*/nullptr, DTN->getName().getIdentifier(),
865 TemplateKWLoc.isValid()},
866 Args: TemplateArgs.arguments());
867
868 // Create source-location information for this type.
869 TypeLocBuilder Builder;
870 DependentTemplateSpecializationTypeLoc SpecTL
871 = Builder.push<DependentTemplateSpecializationTypeLoc>(T);
872 SpecTL.setElaboratedKeywordLoc(SourceLocation());
873 SpecTL.setQualifierLoc(NestedNameSpecifierLoc());
874 SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
875 SpecTL.setTemplateNameLoc(TemplateNameLoc);
876 SpecTL.setLAngleLoc(LAngleLoc);
877 SpecTL.setRAngleLoc(RAngleLoc);
878 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
879 SpecTL.setArgLocInfo(i: I, AI: TemplateArgs[I].getLocInfo());
880
881 SS.Extend(Context, TL: Builder.getTypeLocInContext(Context, T), ColonColonLoc: CCLoc);
882 return false;
883 }
884
885 // If we assumed an undeclared identifier was a template name, try to
886 // typo-correct it now.
887 if (Template.getAsAssumedTemplateName() &&
888 resolveAssumedTemplateNameAsType(S, Name&: Template, NameLoc: TemplateNameLoc))
889 return true;
890
891 TemplateDecl *TD = Template.getAsTemplateDecl();
892 if (Template.getAsOverloadedTemplate() || DTN ||
893 isa<FunctionTemplateDecl>(Val: TD) || isa<VarTemplateDecl>(Val: TD)) {
894 SourceRange R(TemplateNameLoc, RAngleLoc);
895 if (SS.getRange().isValid())
896 R.setBegin(SS.getRange().getBegin());
897
898 Diag(Loc: CCLoc, DiagID: diag::err_non_type_template_in_nested_name_specifier)
899 << isa_and_nonnull<VarTemplateDecl>(Val: TD) << Template << R;
900 NoteAllFoundTemplates(Name: Template);
901 return true;
902 }
903
904 // We were able to resolve the template name to an actual template.
905 // Build an appropriate nested-name-specifier.
906 QualType T = CheckTemplateIdType(Template, TemplateLoc: TemplateNameLoc, TemplateArgs);
907 if (T.isNull())
908 return true;
909
910 // Alias template specializations can produce types which are not valid
911 // nested name specifiers.
912 if (!T->isDependentType() && !T->getAs<TagType>()) {
913 Diag(Loc: TemplateNameLoc, DiagID: diag::err_nested_name_spec_non_tag) << T;
914 NoteAllFoundTemplates(Name: Template);
915 return true;
916 }
917
918 // Provide source-location information for the template specialization type.
919 TypeLocBuilder Builder;
920 TemplateSpecializationTypeLoc SpecTL
921 = Builder.push<TemplateSpecializationTypeLoc>(T);
922 SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
923 SpecTL.setTemplateNameLoc(TemplateNameLoc);
924 SpecTL.setLAngleLoc(LAngleLoc);
925 SpecTL.setRAngleLoc(RAngleLoc);
926 for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
927 SpecTL.setArgLocInfo(i: I, AI: TemplateArgs[I].getLocInfo());
928
929 SS.Extend(Context, TL: Builder.getTypeLocInContext(Context, T), ColonColonLoc: CCLoc);
930 return false;
931}
932
933namespace {
934 /// A structure that stores a nested-name-specifier annotation,
935 /// including both the nested-name-specifier
936 struct NestedNameSpecifierAnnotation {
937 NestedNameSpecifier *NNS;
938 };
939}
940
941void *Sema::SaveNestedNameSpecifierAnnotation(CXXScopeSpec &SS) {
942 if (SS.isEmpty() || SS.isInvalid())
943 return nullptr;
944
945 void *Mem = Context.Allocate(
946 Size: (sizeof(NestedNameSpecifierAnnotation) + SS.location_size()),
947 Align: alignof(NestedNameSpecifierAnnotation));
948 NestedNameSpecifierAnnotation *Annotation
949 = new (Mem) NestedNameSpecifierAnnotation;
950 Annotation->NNS = SS.getScopeRep();
951 memcpy(dest: Annotation + 1, src: SS.location_data(), n: SS.location_size());
952 return Annotation;
953}
954
955void Sema::RestoreNestedNameSpecifierAnnotation(void *AnnotationPtr,
956 SourceRange AnnotationRange,
957 CXXScopeSpec &SS) {
958 if (!AnnotationPtr) {
959 SS.SetInvalid(AnnotationRange);
960 return;
961 }
962
963 NestedNameSpecifierAnnotation *Annotation
964 = static_cast<NestedNameSpecifierAnnotation *>(AnnotationPtr);
965 SS.Adopt(Other: NestedNameSpecifierLoc(Annotation->NNS, Annotation + 1));
966}
967
968bool Sema::ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
969 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
970
971 // Don't enter a declarator context when the current context is an Objective-C
972 // declaration.
973 if (isa<ObjCContainerDecl>(Val: CurContext) || isa<ObjCMethodDecl>(Val: CurContext))
974 return false;
975
976 NestedNameSpecifier *Qualifier = SS.getScopeRep();
977
978 // There are only two places a well-formed program may qualify a
979 // declarator: first, when defining a namespace or class member
980 // out-of-line, and second, when naming an explicitly-qualified
981 // friend function. The latter case is governed by
982 // C++03 [basic.lookup.unqual]p10:
983 // In a friend declaration naming a member function, a name used
984 // in the function declarator and not part of a template-argument
985 // in a template-id is first looked up in the scope of the member
986 // function's class. If it is not found, or if the name is part of
987 // a template-argument in a template-id, the look up is as
988 // described for unqualified names in the definition of the class
989 // granting friendship.
990 // i.e. we don't push a scope unless it's a class member.
991
992 switch (Qualifier->getKind()) {
993 case NestedNameSpecifier::Global:
994 case NestedNameSpecifier::Namespace:
995 case NestedNameSpecifier::NamespaceAlias:
996 // These are always namespace scopes. We never want to enter a
997 // namespace scope from anything but a file context.
998 return CurContext->getRedeclContext()->isFileContext();
999
1000 case NestedNameSpecifier::Identifier:
1001 case NestedNameSpecifier::TypeSpec:
1002 case NestedNameSpecifier::Super:
1003 // These are never namespace scopes.
1004 return true;
1005 }
1006
1007 llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
1008}
1009
1010bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, CXXScopeSpec &SS) {
1011 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
1012
1013 if (SS.isInvalid()) return true;
1014
1015 DeclContext *DC = computeDeclContext(SS, EnteringContext: true);
1016 if (!DC) return true;
1017
1018 // Before we enter a declarator's context, we need to make sure that
1019 // it is a complete declaration context.
1020 if (!DC->isDependentContext() && RequireCompleteDeclContext(SS, DC))
1021 return true;
1022
1023 EnterDeclaratorContext(S, DC);
1024
1025 // Rebuild the nested name specifier for the new scope.
1026 if (DC->isDependentContext())
1027 RebuildNestedNameSpecifierInCurrentInstantiation(SS);
1028
1029 return false;
1030}
1031
1032void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
1033 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
1034 if (SS.isInvalid())
1035 return;
1036 assert(!SS.isInvalid() && computeDeclContext(SS, true) &&
1037 "exiting declarator scope we never really entered");
1038 ExitDeclaratorContext(S);
1039}
1040