1	//===--------------------- SemaLookup.cpp - Name Lookup ------------------===//
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 name lookup for C, C++, Objective-C, and
10	// Objective-C++.
11	//
12	//===----------------------------------------------------------------------===//
13
14	#include "clang/AST/ASTContext.h"
15	#include "clang/AST/CXXInheritance.h"
16	#include "clang/AST/Decl.h"
17	#include "clang/AST/DeclCXX.h"
18	#include "clang/AST/DeclLookups.h"
19	#include "clang/AST/DeclObjC.h"
20	#include "clang/AST/DeclTemplate.h"
21	#include "clang/AST/Expr.h"
22	#include "clang/AST/ExprCXX.h"
23	#include "clang/Basic/Builtins.h"
24	#include "clang/Basic/FileManager.h"
25	#include "clang/Basic/LangOptions.h"
26	#include "clang/Lex/HeaderSearch.h"
27	#include "clang/Lex/ModuleLoader.h"
28	#include "clang/Lex/Preprocessor.h"
29	#include "clang/Sema/DeclSpec.h"
30	#include "clang/Sema/Lookup.h"
31	#include "clang/Sema/Overload.h"
32	#include "clang/Sema/RISCVIntrinsicManager.h"
33	#include "clang/Sema/Scope.h"
34	#include "clang/Sema/ScopeInfo.h"
35	#include "clang/Sema/Sema.h"
36	#include "clang/Sema/SemaInternal.h"
37	#include "clang/Sema/TemplateDeduction.h"
38	#include "clang/Sema/TypoCorrection.h"
39	#include "llvm/ADT/STLExtras.h"
40	#include "llvm/ADT/STLForwardCompat.h"
41	#include "llvm/ADT/SmallPtrSet.h"
42	#include "llvm/ADT/TinyPtrVector.h"
43	#include "llvm/ADT/edit_distance.h"
44	#include "llvm/Support/Casting.h"
45	#include "llvm/Support/ErrorHandling.h"
46	#include <algorithm>
47	#include <iterator>
48	#include <list>
49	#include <optional>
50	#include <set>
51	#include <utility>
52	#include <vector>
53
54	#include "OpenCLBuiltins.inc"
55
56	using namespace clang;
57	using namespace sema;
58
59	namespace {
60	class UnqualUsingEntry {
61	const DeclContext *Nominated;
62	const DeclContext *CommonAncestor;
63
64	public:
65	UnqualUsingEntry(const DeclContext *Nominated,
66	const DeclContext *CommonAncestor)
67	: Nominated(Nominated), CommonAncestor(CommonAncestor) {
68	}
69
70	const DeclContext *getCommonAncestor() const {
71	return CommonAncestor;
72	}
73
74	const DeclContext *getNominatedNamespace() const {
75	return Nominated;
76	}
77
78	// Sort by the pointer value of the common ancestor.
79	struct Comparator {
80	bool operator()(const UnqualUsingEntry &L, const UnqualUsingEntry &R) {
81	return L.getCommonAncestor() < R.getCommonAncestor();
82	}
83
84	bool operator()(const UnqualUsingEntry &E, const DeclContext *DC) {
85	return E.getCommonAncestor() < DC;
86	}
87
88	bool operator()(const DeclContext *DC, const UnqualUsingEntry &E) {
89	return DC < E.getCommonAncestor();
90	}
91	};
92	};
93
94	/// A collection of using directives, as used by C++ unqualified
95	/// lookup.
96	class UnqualUsingDirectiveSet {
97	Sema &SemaRef;
98
99	typedef SmallVector<UnqualUsingEntry, 8> ListTy;
100
101	ListTy list;
102	llvm::SmallPtrSet<DeclContext*, 8> visited;
103
104	public:
105	UnqualUsingDirectiveSet(Sema &SemaRef) : SemaRef(SemaRef) {}
106
107	void visitScopeChain(Scope *S, Scope *InnermostFileScope) {
108	// C++ [namespace.udir]p1:
109	// During unqualified name lookup, the names appear as if they
110	// were declared in the nearest enclosing namespace which contains
111	// both the using-directive and the nominated namespace.
112	DeclContext *InnermostFileDC = InnermostFileScope->getEntity();
113	assert(InnermostFileDC && InnermostFileDC->isFileContext());
114
115	for (; S; S = S->getParent()) {
116	// C++ [namespace.udir]p1:
117	// A using-directive shall not appear in class scope, but may
118	// appear in namespace scope or in block scope.
119	DeclContext *Ctx = S->getEntity();
120	if (Ctx && Ctx->isFileContext()) {
121	visit(DC: Ctx, EffectiveDC: Ctx);
122	} else if (!Ctx || Ctx->isFunctionOrMethod()) {
123	for (auto *I : S->using_directives())
124	if (SemaRef.isVisible(I))
125	visit(I, InnermostFileDC);
126	}
127	}
128	}
129
130	// Visits a context and collect all of its using directives
131	// recursively. Treats all using directives as if they were
132	// declared in the context.
133	//
134	// A given context is only every visited once, so it is important
135	// that contexts be visited from the inside out in order to get
136	// the effective DCs right.
137	void visit(DeclContext *DC, DeclContext *EffectiveDC) {
138	if (!visited.insert(DC).second)
139	return;
140
141	addUsingDirectives(DC, EffectiveDC);
142	}
143
144	// Visits a using directive and collects all of its using
145	// directives recursively. Treats all using directives as if they
146	// were declared in the effective DC.
147	void visit(UsingDirectiveDecl *UD, DeclContext *EffectiveDC) {
148	DeclContext *NS = UD->getNominatedNamespace();
149	if (!visited.insert(NS).second)
150	return;
151
152	addUsingDirective(UD, EffectiveDC);
153	addUsingDirectives(DC: NS, EffectiveDC);
154	}
155
156	// Adds all the using directives in a context (and those nominated
157	// by its using directives, transitively) as if they appeared in
158	// the given effective context.
159	void addUsingDirectives(DeclContext *DC, DeclContext *EffectiveDC) {
160	SmallVector<DeclContext*, 4> queue;
161	while (true) {
162	for (auto *UD : DC->using_directives()) {
163	DeclContext *NS = UD->getNominatedNamespace();
164	if (SemaRef.isVisible(UD) && visited.insert(NS).second) {
165	addUsingDirective(UD, EffectiveDC);
166	queue.push_back(NS);
167	}
168	}
169
170	if (queue.empty())
171	return;
172
173	DC = queue.pop_back_val();
174	}
175	}
176
177	// Add a using directive as if it had been declared in the given
178	// context. This helps implement C++ [namespace.udir]p3:
179	// The using-directive is transitive: if a scope contains a
180	// using-directive that nominates a second namespace that itself
181	// contains using-directives, the effect is as if the
182	// using-directives from the second namespace also appeared in
183	// the first.
184	void addUsingDirective(UsingDirectiveDecl *UD, DeclContext *EffectiveDC) {
185	// Find the common ancestor between the effective context and
186	// the nominated namespace.
187	DeclContext *Common = UD->getNominatedNamespace();
188	while (!Common->Encloses(DC: EffectiveDC))
189	Common = Common->getParent();
190	Common = Common->getPrimaryContext();
191
192	list.push_back(UnqualUsingEntry(UD->getNominatedNamespace(), Common));
193	}
194
195	void done() { llvm::sort(list, UnqualUsingEntry::Comparator()); }
196
197	typedef ListTy::const_iterator const_iterator;
198
199	const_iterator begin() const { return list.begin(); }
200	const_iterator end() const { return list.end(); }
201
202	llvm::iterator_range<const_iterator>
203	getNamespacesFor(const DeclContext *DC) const {
204	return llvm::make_range(std::equal_range(begin(), end(),
205	DC->getPrimaryContext(),
206	UnqualUsingEntry::Comparator()));
207	}
208	};
209	} // end anonymous namespace
210
211	// Retrieve the set of identifier namespaces that correspond to a
212	// specific kind of name lookup.
213	static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
214	bool CPlusPlus,
215	bool Redeclaration) {
216	unsigned IDNS = 0;
217	switch (NameKind) {
218	case Sema::LookupObjCImplicitSelfParam:
219	case Sema::LookupOrdinaryName:
220	case Sema::LookupRedeclarationWithLinkage:
221	case Sema::LookupLocalFriendName:
222	case Sema::LookupDestructorName:
223	IDNS = Decl::IDNS_Ordinary;
224	if (CPlusPlus) {
225	IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member | Decl::IDNS_Namespace;
226	if (Redeclaration)
227	IDNS |= Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend;
228	}
229	if (Redeclaration)
230	IDNS |= Decl::IDNS_LocalExtern;
231	break;
232
233	case Sema::LookupOperatorName:
234	// Operator lookup is its own crazy thing; it is not the same
235	// as (e.g.) looking up an operator name for redeclaration.
236	assert(!Redeclaration && "cannot do redeclaration operator lookup");
237	IDNS = Decl::IDNS_NonMemberOperator;
238	break;
239
240	case Sema::LookupTagName:
241	if (CPlusPlus) {
242	IDNS = Decl::IDNS_Type;
243
244	// When looking for a redeclaration of a tag name, we add:
245	// 1) TagFriend to find undeclared friend decls
246	// 2) Namespace because they can't "overload" with tag decls.
247	// 3) Tag because it includes class templates, which can't
248	// "overload" with tag decls.
249	if (Redeclaration)
250	IDNS |= Decl::IDNS_Tag | Decl::IDNS_TagFriend | Decl::IDNS_Namespace;
251	} else {
252	IDNS = Decl::IDNS_Tag;
253	}
254	break;
255
256	case Sema::LookupLabel:
257	IDNS = Decl::IDNS_Label;
258	break;
259
260	case Sema::LookupMemberName:
261	IDNS = Decl::IDNS_Member;
262	if (CPlusPlus)
263	IDNS |= Decl::IDNS_Tag | Decl::IDNS_Ordinary;
264	break;
265
266	case Sema::LookupNestedNameSpecifierName:
267	IDNS = Decl::IDNS_Type | Decl::IDNS_Namespace;
268	break;
269
270	case Sema::LookupNamespaceName:
271	IDNS = Decl::IDNS_Namespace;
272	break;
273
274	case Sema::LookupUsingDeclName:
275	assert(Redeclaration && "should only be used for redecl lookup");
276	IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member |
277	Decl::IDNS_Using | Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend |
278	Decl::IDNS_LocalExtern;
279	break;
280
281	case Sema::LookupObjCProtocolName:
282	IDNS = Decl::IDNS_ObjCProtocol;
283	break;
284
285	case Sema::LookupOMPReductionName:
286	IDNS = Decl::IDNS_OMPReduction;
287	break;
288
289	case Sema::LookupOMPMapperName:
290	IDNS = Decl::IDNS_OMPMapper;
291	break;
292
293	case Sema::LookupAnyName:
294	IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member
295	| Decl::IDNS_Using | Decl::IDNS_Namespace | Decl::IDNS_ObjCProtocol
296	| Decl::IDNS_Type;
297	break;
298	}
299	return IDNS;
300	}
301
302	void LookupResult::configure() {
303	IDNS = getIDNS(NameKind: LookupKind, CPlusPlus: getSema().getLangOpts().CPlusPlus,
304	Redeclaration: isForRedeclaration());
305
306	// If we're looking for one of the allocation or deallocation
307	// operators, make sure that the implicitly-declared new and delete
308	// operators can be found.
309	switch (NameInfo.getName().getCXXOverloadedOperator()) {
310	case OO_New:
311	case OO_Delete:
312	case OO_Array_New:
313	case OO_Array_Delete:
314	getSema().DeclareGlobalNewDelete();
315	break;
316
317	default:
318	break;
319	}
320
321	// Compiler builtins are always visible, regardless of where they end
322	// up being declared.
323	if (IdentifierInfo *Id = NameInfo.getName().getAsIdentifierInfo()) {
324	if (unsigned BuiltinID = Id->getBuiltinID()) {
325	if (!getSema().Context.BuiltinInfo.isPredefinedLibFunction(ID: BuiltinID))
326	AllowHidden = true;
327	}
328	}
329	}
330
331	bool LookupResult::checkDebugAssumptions() const {
332	// This function is never called by NDEBUG builds.
333	assert(ResultKind != NotFound || Decls.size() == 0);
334	assert(ResultKind != Found || Decls.size() == 1);
335	assert(ResultKind != FoundOverloaded || Decls.size() > 1 ||
336	(Decls.size() == 1 &&
337	isa<FunctionTemplateDecl>((*begin())->getUnderlyingDecl())));
338	assert(ResultKind != FoundUnresolvedValue || checkUnresolved());
339	assert(ResultKind != Ambiguous || Decls.size() > 1 ||
340	(Decls.size() == 1 && (Ambiguity == AmbiguousBaseSubobjects ||
341	Ambiguity == AmbiguousBaseSubobjectTypes)));
342	assert((Paths != nullptr) == (ResultKind == Ambiguous &&
343	(Ambiguity == AmbiguousBaseSubobjectTypes ||
344	Ambiguity == AmbiguousBaseSubobjects)));
345	return true;
346	}
347
348	// Necessary because CXXBasePaths is not complete in Sema.h
349	void LookupResult::deletePaths(CXXBasePaths *Paths) {
350	delete Paths;
351	}
352
353	/// Get a representative context for a declaration such that two declarations
354	/// will have the same context if they were found within the same scope.
355	static const DeclContext *getContextForScopeMatching(const Decl *D) {
356	// For function-local declarations, use that function as the context. This
357	// doesn't account for scopes within the function; the caller must deal with
358	// those.
359	if (const DeclContext *DC = D->getLexicalDeclContext();
360	DC->isFunctionOrMethod())
361	return DC;
362
363	// Otherwise, look at the semantic context of the declaration. The
364	// declaration must have been found there.
365	return D->getDeclContext()->getRedeclContext();
366	}
367
368	/// Determine whether \p D is a better lookup result than \p Existing,
369	/// given that they declare the same entity.
370	static bool isPreferredLookupResult(Sema &S, Sema::LookupNameKind Kind,
371	const NamedDecl *D,
372	const NamedDecl *Existing) {
373	// When looking up redeclarations of a using declaration, prefer a using
374	// shadow declaration over any other declaration of the same entity.
375	if (Kind == Sema::LookupUsingDeclName && isa<UsingShadowDecl>(Val: D) &&
376	!isa<UsingShadowDecl>(Val: Existing))
377	return true;
378
379	const auto *DUnderlying = D->getUnderlyingDecl();
380	const auto *EUnderlying = Existing->getUnderlyingDecl();
381
382	// If they have different underlying declarations, prefer a typedef over the
383	// original type (this happens when two type declarations denote the same
384	// type), per a generous reading of C++ [dcl.typedef]p3 and p4. The typedef
385	// might carry additional semantic information, such as an alignment override.
386	// However, per C++ [dcl.typedef]p5, when looking up a tag name, prefer a tag
387	// declaration over a typedef. Also prefer a tag over a typedef for
388	// destructor name lookup because in some contexts we only accept a
389	// class-name in a destructor declaration.
390	if (DUnderlying->getCanonicalDecl() != EUnderlying->getCanonicalDecl()) {
391	assert(isa<TypeDecl>(DUnderlying) && isa<TypeDecl>(EUnderlying));
392	bool HaveTag = isa<TagDecl>(Val: EUnderlying);
393	bool WantTag =
394	Kind == Sema::LookupTagName || Kind == Sema::LookupDestructorName;
395	return HaveTag != WantTag;
396	}
397
398	// Pick the function with more default arguments.
399	// FIXME: In the presence of ambiguous default arguments, we should keep both,
400	// so we can diagnose the ambiguity if the default argument is needed.
401	// See C++ [over.match.best]p3.
402	if (const auto *DFD = dyn_cast<FunctionDecl>(Val: DUnderlying)) {
403	const auto *EFD = cast<FunctionDecl>(Val: EUnderlying);
404	unsigned DMin = DFD->getMinRequiredArguments();
405	unsigned EMin = EFD->getMinRequiredArguments();
406	// If D has more default arguments, it is preferred.
407	if (DMin != EMin)
408	return DMin < EMin;
409	// FIXME: When we track visibility for default function arguments, check
410	// that we pick the declaration with more visible default arguments.
411	}
412
413	// Pick the template with more default template arguments.
414	if (const auto *DTD = dyn_cast<TemplateDecl>(Val: DUnderlying)) {
415	const auto *ETD = cast<TemplateDecl>(Val: EUnderlying);
416	unsigned DMin = DTD->getTemplateParameters()->getMinRequiredArguments();
417	unsigned EMin = ETD->getTemplateParameters()->getMinRequiredArguments();
418	// If D has more default arguments, it is preferred. Note that default
419	// arguments (and their visibility) is monotonically increasing across the
420	// redeclaration chain, so this is a quick proxy for "is more recent".
421	if (DMin != EMin)
422	return DMin < EMin;
423	// If D has more *visible* default arguments, it is preferred. Note, an
424	// earlier default argument being visible does not imply that a later
425	// default argument is visible, so we can't just check the first one.
426	for (unsigned I = DMin, N = DTD->getTemplateParameters()->size();
427	I != N; ++I) {
428	if (!S.hasVisibleDefaultArgument(
429	D: ETD->getTemplateParameters()->getParam(Idx: I)) &&
430	S.hasVisibleDefaultArgument(
431	D: DTD->getTemplateParameters()->getParam(Idx: I)))
432	return true;
433	}
434	}
435
436	// VarDecl can have incomplete array types, prefer the one with more complete
437	// array type.
438	if (const auto *DVD = dyn_cast<VarDecl>(Val: DUnderlying)) {
439	const auto *EVD = cast<VarDecl>(Val: EUnderlying);
440	if (EVD->getType()->isIncompleteType() &&
441	!DVD->getType()->isIncompleteType()) {
442	// Prefer the decl with a more complete type if visible.
443	return S.isVisible(DVD);
444	}
445	return false; // Avoid picking up a newer decl, just because it was newer.
446	}
447
448	// For most kinds of declaration, it doesn't really matter which one we pick.
449	if (!isa<FunctionDecl>(Val: DUnderlying) && !isa<VarDecl>(Val: DUnderlying)) {
450	// If the existing declaration is hidden, prefer the new one. Otherwise,
451	// keep what we've got.
452	return !S.isVisible(D: Existing);
453	}
454
455	// Pick the newer declaration; it might have a more precise type.
456	for (const Decl *Prev = DUnderlying->getPreviousDecl(); Prev;
457	Prev = Prev->getPreviousDecl())
458	if (Prev == EUnderlying)
459	return true;
460	return false;
461	}
462
463	/// Determine whether \p D can hide a tag declaration.
464	static bool canHideTag(const NamedDecl *D) {
465	// C++ [basic.scope.declarative]p4:
466	// Given a set of declarations in a single declarative region [...]
467	// exactly one declaration shall declare a class name or enumeration name
468	// that is not a typedef name and the other declarations shall all refer to
469	// the same variable, non-static data member, or enumerator, or all refer
470	// to functions and function templates; in this case the class name or
471	// enumeration name is hidden.
472	// C++ [basic.scope.hiding]p2:
473	// A class name or enumeration name can be hidden by the name of a
474	// variable, data member, function, or enumerator declared in the same
475	// scope.
476	// An UnresolvedUsingValueDecl always instantiates to one of these.
477	D = D->getUnderlyingDecl();
478	return isa<VarDecl>(Val: D) || isa<EnumConstantDecl>(Val: D) || isa<FunctionDecl>(Val: D) ||
479	isa<FunctionTemplateDecl>(Val: D) || isa<FieldDecl>(Val: D) ||
480	isa<UnresolvedUsingValueDecl>(Val: D);
481	}
482
483	/// Resolves the result kind of this lookup.
484	void LookupResult::resolveKind() {
485	unsigned N = Decls.size();
486
487	// Fast case: no possible ambiguity.
488	if (N == 0) {
489	assert(ResultKind == NotFound ||
490	ResultKind == NotFoundInCurrentInstantiation);
491	return;
492	}
493
494	// If there's a single decl, we need to examine it to decide what
495	// kind of lookup this is.
496	if (N == 1) {
497	const NamedDecl *D = (*Decls.begin())->getUnderlyingDecl();
498	if (isa<FunctionTemplateDecl>(Val: D))
499	ResultKind = FoundOverloaded;
500	else if (isa<UnresolvedUsingValueDecl>(Val: D))
501	ResultKind = FoundUnresolvedValue;
502	return;
503	}
504
505	// Don't do any extra resolution if we've already resolved as ambiguous.
506	if (ResultKind == Ambiguous) return;
507
508	llvm::SmallDenseMap<const NamedDecl *, unsigned, 16> Unique;
509	llvm::SmallDenseMap<QualType, unsigned, 16> UniqueTypes;
510
511	bool Ambiguous = false;
512	bool ReferenceToPlaceHolderVariable = false;
513	bool HasTag = false, HasFunction = false;
514	bool HasFunctionTemplate = false, HasUnresolved = false;
515	const NamedDecl *HasNonFunction = nullptr;
516
517	llvm::SmallVector<const NamedDecl *, 4> EquivalentNonFunctions;
518	llvm::BitVector RemovedDecls(N);
519
520	for (unsigned I = 0; I < N; I++) {
521	const NamedDecl *D = Decls[I]->getUnderlyingDecl();
522	D = cast<NamedDecl>(D->getCanonicalDecl());
523
524	// Ignore an invalid declaration unless it's the only one left.
525	// Also ignore HLSLBufferDecl which not have name conflict with other Decls.
526	if ((D->isInvalidDecl() || isa<HLSLBufferDecl>(Val: D)) &&
527	N - RemovedDecls.count() > 1) {
528	RemovedDecls.set(I);
529	continue;
530	}
531
532	// C++ [basic.scope.hiding]p2:
533	// A class name or enumeration name can be hidden by the name of
534	// an object, function, or enumerator declared in the same
535	// scope. If a class or enumeration name and an object, function,
536	// or enumerator are declared in the same scope (in any order)
537	// with the same name, the class or enumeration name is hidden
538	// wherever the object, function, or enumerator name is visible.
539	if (HideTags && isa<TagDecl>(Val: D)) {
540	bool Hidden = false;
541	for (auto *OtherDecl : Decls) {
542	if (canHideTag(D: OtherDecl) && !OtherDecl->isInvalidDecl() &&
543	getContextForScopeMatching(OtherDecl)->Equals(
544	DC: getContextForScopeMatching(Decls[I]))) {
545	RemovedDecls.set(I);
546	Hidden = true;
547	break;
548	}
549	}
550	if (Hidden)
551	continue;
552	}
553
554	std::optional<unsigned> ExistingI;
555
556	// Redeclarations of types via typedef can occur both within a scope
557	// and, through using declarations and directives, across scopes. There is
558	// no ambiguity if they all refer to the same type, so unique based on the
559	// canonical type.
560	if (const auto *TD = dyn_cast<TypeDecl>(Val: D)) {
561	QualType T = getSema().Context.getTypeDeclType(Decl: TD);
562	auto UniqueResult = UniqueTypes.insert(
563	std::make_pair(x: getSema().Context.getCanonicalType(T), y&: I));
564	if (!UniqueResult.second) {
565	// The type is not unique.
566	ExistingI = UniqueResult.first->second;
567	}
568	}
569
570	// For non-type declarations, check for a prior lookup result naming this
571	// canonical declaration.
572	if (!D->isPlaceholderVar(LangOpts: getSema().getLangOpts()) && !ExistingI) {
573	auto UniqueResult = Unique.insert(KV: std::make_pair(x&: D, y&: I));
574	if (!UniqueResult.second) {
575	// We've seen this entity before.
576	ExistingI = UniqueResult.first->second;
577	}
578	}
579
580	if (ExistingI) {
581	// This is not a unique lookup result. Pick one of the results and
582	// discard the other.
583	if (isPreferredLookupResult(S&: getSema(), Kind: getLookupKind(), D: Decls[I],
584	Existing: Decls[*ExistingI]))
585	Decls[*ExistingI] = Decls[I];
586	RemovedDecls.set(I);
587	continue;
588	}
589
590	// Otherwise, do some decl type analysis and then continue.
591
592	if (isa<UnresolvedUsingValueDecl>(Val: D)) {
593	HasUnresolved = true;
594	} else if (isa<TagDecl>(Val: D)) {
595	if (HasTag)
596	Ambiguous = true;
597	HasTag = true;
598	} else if (isa<FunctionTemplateDecl>(Val: D)) {
599	HasFunction = true;
600	HasFunctionTemplate = true;
601	} else if (isa<FunctionDecl>(Val: D)) {
602	HasFunction = true;
603	} else {
604	if (HasNonFunction) {
605	// If we're about to create an ambiguity between two declarations that
606	// are equivalent, but one is an internal linkage declaration from one
607	// module and the other is an internal linkage declaration from another
608	// module, just skip it.
609	if (getSema().isEquivalentInternalLinkageDeclaration(A: HasNonFunction,
610	B: D)) {
611	EquivalentNonFunctions.push_back(Elt: D);
612	RemovedDecls.set(I);
613	continue;
614	}
615	if (D->isPlaceholderVar(LangOpts: getSema().getLangOpts()) &&
616	getContextForScopeMatching(D) ==
617	getContextForScopeMatching(Decls[I])) {
618	ReferenceToPlaceHolderVariable = true;
619	}
620	Ambiguous = true;
621	}
622	HasNonFunction = D;
623	}
624	}
625
626	// FIXME: This diagnostic should really be delayed until we're done with
627	// the lookup result, in case the ambiguity is resolved by the caller.
628	if (!EquivalentNonFunctions.empty() && !Ambiguous)
629	getSema().diagnoseEquivalentInternalLinkageDeclarations(
630	Loc: getNameLoc(), D: HasNonFunction, Equiv: EquivalentNonFunctions);
631
632	// Remove decls by replacing them with decls from the end (which
633	// means that we need to iterate from the end) and then truncating
634	// to the new size.
635	for (int I = RemovedDecls.find_last(); I >= 0; I = RemovedDecls.find_prev(PriorTo: I))
636	Decls[I] = Decls[--N];
637	Decls.truncate(N);
638
639	if ((HasNonFunction && (HasFunction || HasUnresolved)) ||
640	(HideTags && HasTag && (HasFunction || HasNonFunction || HasUnresolved)))
641	Ambiguous = true;
642
643	if (Ambiguous && ReferenceToPlaceHolderVariable)
644	setAmbiguous(LookupResult::AmbiguousReferenceToPlaceholderVariable);
645	else if (Ambiguous)
646	setAmbiguous(LookupResult::AmbiguousReference);
647	else if (HasUnresolved)
648	ResultKind = LookupResult::FoundUnresolvedValue;
649	else if (N > 1 || HasFunctionTemplate)
650	ResultKind = LookupResult::FoundOverloaded;
651	else
652	ResultKind = LookupResult::Found;
653	}
654
655	void LookupResult::addDeclsFromBasePaths(const CXXBasePaths &P) {
656	CXXBasePaths::const_paths_iterator I, E;
657	for (I = P.begin(), E = P.end(); I != E; ++I)
658	for (DeclContext::lookup_iterator DI = I->Decls, DE = DI.end(); DI != DE;
659	++DI)
660	addDecl(D: *DI);
661	}
662
663	void LookupResult::setAmbiguousBaseSubobjects(CXXBasePaths &P) {
664	Paths = new CXXBasePaths;
665	Paths->swap(Other&: P);
666	addDeclsFromBasePaths(P: *Paths);
667	resolveKind();
668	setAmbiguous(AmbiguousBaseSubobjects);
669	}
670
671	void LookupResult::setAmbiguousBaseSubobjectTypes(CXXBasePaths &P) {
672	Paths = new CXXBasePaths;
673	Paths->swap(Other&: P);
674	addDeclsFromBasePaths(P: *Paths);
675	resolveKind();
676	setAmbiguous(AmbiguousBaseSubobjectTypes);
677	}
678
679	void LookupResult::print(raw_ostream &Out) {
680	Out << Decls.size() << " result(s)";
681	if (isAmbiguous()) Out << ", ambiguous";
682	if (Paths) Out << ", base paths present";
683
684	for (iterator I = begin(), E = end(); I != E; ++I) {
685	Out << "\n";
686	(*I)->print(Out, 2);
687	}
688	}
689
690	LLVM_DUMP_METHOD void LookupResult::dump() {
691	llvm::errs() << "lookup results for " << getLookupName().getAsString()
692	<< ":\n";
693	for (NamedDecl *D : *this)
694	D->dump();
695	}
696
697	/// Diagnose a missing builtin type.
698	static QualType diagOpenCLBuiltinTypeError(Sema &S, llvm::StringRef TypeClass,
699	llvm::StringRef Name) {
700	S.Diag(SourceLocation(), diag::err_opencl_type_not_found)
701	<< TypeClass << Name;
702	return S.Context.VoidTy;
703	}
704
705	/// Lookup an OpenCL enum type.
706	static QualType getOpenCLEnumType(Sema &S, llvm::StringRef Name) {
707	LookupResult Result(S, &S.Context.Idents.get(Name), SourceLocation(),
708	Sema::LookupTagName);
709	S.LookupName(R&: Result, S: S.TUScope);
710	if (Result.empty())
711	return diagOpenCLBuiltinTypeError(S, TypeClass: "enum", Name);
712	EnumDecl *Decl = Result.getAsSingle<EnumDecl>();
713	if (!Decl)
714	return diagOpenCLBuiltinTypeError(S, TypeClass: "enum", Name);
715	return S.Context.getEnumType(Decl);
716	}
717
718	/// Lookup an OpenCL typedef type.
719	static QualType getOpenCLTypedefType(Sema &S, llvm::StringRef Name) {
720	LookupResult Result(S, &S.Context.Idents.get(Name), SourceLocation(),
721	Sema::LookupOrdinaryName);
722	S.LookupName(R&: Result, S: S.TUScope);
723	if (Result.empty())
724	return diagOpenCLBuiltinTypeError(S, TypeClass: "typedef", Name);
725	TypedefNameDecl *Decl = Result.getAsSingle<TypedefNameDecl>();
726	if (!Decl)
727	return diagOpenCLBuiltinTypeError(S, TypeClass: "typedef", Name);
728	return S.Context.getTypedefType(Decl);
729	}
730
731	/// Get the QualType instances of the return type and arguments for an OpenCL
732	/// builtin function signature.
733	/// \param S (in) The Sema instance.
734	/// \param OpenCLBuiltin (in) The signature currently handled.
735	/// \param GenTypeMaxCnt (out) Maximum number of types contained in a generic
736	/// type used as return type or as argument.
737	/// Only meaningful for generic types, otherwise equals 1.
738	/// \param RetTypes (out) List of the possible return types.
739	/// \param ArgTypes (out) List of the possible argument types. For each
740	/// argument, ArgTypes contains QualTypes for the Cartesian product
741	/// of (vector sizes) x (types) .
742	static void GetQualTypesForOpenCLBuiltin(
743	Sema &S, const OpenCLBuiltinStruct &OpenCLBuiltin, unsigned &GenTypeMaxCnt,
744	SmallVector<QualType, 1> &RetTypes,
745	SmallVector<SmallVector<QualType, 1>, 5> &ArgTypes) {
746	// Get the QualType instances of the return types.
747	unsigned Sig = SignatureTable[OpenCLBuiltin.SigTableIndex];
748	OCL2Qual(S, TypeTable[Sig], RetTypes);
749	GenTypeMaxCnt = RetTypes.size();
750
751	// Get the QualType instances of the arguments.
752	// First type is the return type, skip it.
753	for (unsigned Index = 1; Index < OpenCLBuiltin.NumTypes; Index++) {
754	SmallVector<QualType, 1> Ty;
755	OCL2Qual(S, TypeTable[SignatureTable[OpenCLBuiltin.SigTableIndex + Index]],
756	Ty);
757	GenTypeMaxCnt = (Ty.size() > GenTypeMaxCnt) ? Ty.size() : GenTypeMaxCnt;
758	ArgTypes.push_back(Elt: std::move(Ty));
759	}
760	}
761
762	/// Create a list of the candidate function overloads for an OpenCL builtin
763	/// function.
764	/// \param Context (in) The ASTContext instance.
765	/// \param GenTypeMaxCnt (in) Maximum number of types contained in a generic
766	/// type used as return type or as argument.
767	/// Only meaningful for generic types, otherwise equals 1.
768	/// \param FunctionList (out) List of FunctionTypes.
769	/// \param RetTypes (in) List of the possible return types.
770	/// \param ArgTypes (in) List of the possible types for the arguments.
771	static void GetOpenCLBuiltinFctOverloads(
772	ASTContext &Context, unsigned GenTypeMaxCnt,
773	std::vector<QualType> &FunctionList, SmallVector<QualType, 1> &RetTypes,
774	SmallVector<SmallVector<QualType, 1>, 5> &ArgTypes) {
775	FunctionProtoType::ExtProtoInfo PI(
776	Context.getDefaultCallingConvention(IsVariadic: false, IsCXXMethod: false, IsBuiltin: true));
777	PI.Variadic = false;
778
779	// Do not attempt to create any FunctionTypes if there are no return types,
780	// which happens when a type belongs to a disabled extension.
781	if (RetTypes.size() == 0)
782	return;
783
784	// Create FunctionTypes for each (gen)type.
785	for (unsigned IGenType = 0; IGenType < GenTypeMaxCnt; IGenType++) {
786	SmallVector<QualType, 5> ArgList;
787
788	for (unsigned A = 0; A < ArgTypes.size(); A++) {
789	// Bail out if there is an argument that has no available types.
790	if (ArgTypes[A].size() == 0)
791	return;
792
793	// Builtins such as "max" have an "sgentype" argument that represents
794	// the corresponding scalar type of a gentype. The number of gentypes
795	// must be a multiple of the number of sgentypes.
796	assert(GenTypeMaxCnt % ArgTypes[A].size() == 0 &&
797	"argument type count not compatible with gentype type count");
798	unsigned Idx = IGenType % ArgTypes[A].size();
799	ArgList.push_back(Elt: ArgTypes[A][Idx]);
800	}
801
802	FunctionList.push_back(x: Context.getFunctionType(
803	ResultTy: RetTypes[(RetTypes.size() != 1) ? IGenType : 0], Args: ArgList, EPI: PI));
804	}
805	}
806
807	/// When trying to resolve a function name, if isOpenCLBuiltin() returns a
808	/// non-null <Index, Len> pair, then the name is referencing an OpenCL
809	/// builtin function. Add all candidate signatures to the LookUpResult.
810	///
811	/// \param S (in) The Sema instance.
812	/// \param LR (inout) The LookupResult instance.
813	/// \param II (in) The identifier being resolved.
814	/// \param FctIndex (in) Starting index in the BuiltinTable.
815	/// \param Len (in) The signature list has Len elements.
816	static void InsertOCLBuiltinDeclarationsFromTable(Sema &S, LookupResult &LR,
817	IdentifierInfo *II,
818	const unsigned FctIndex,
819	const unsigned Len) {
820	// The builtin function declaration uses generic types (gentype).
821	bool HasGenType = false;
822
823	// Maximum number of types contained in a generic type used as return type or
824	// as argument. Only meaningful for generic types, otherwise equals 1.
825	unsigned GenTypeMaxCnt;
826
827	ASTContext &Context = S.Context;
828
829	for (unsigned SignatureIndex = 0; SignatureIndex < Len; SignatureIndex++) {
830	const OpenCLBuiltinStruct &OpenCLBuiltin =
831	BuiltinTable[FctIndex + SignatureIndex];
832
833	// Ignore this builtin function if it is not available in the currently
834	// selected language version.
835	if (!isOpenCLVersionContainedInMask(Context.getLangOpts(),
836	OpenCLBuiltin.Versions))
837	continue;
838
839	// Ignore this builtin function if it carries an extension macro that is
840	// not defined. This indicates that the extension is not supported by the
841	// target, so the builtin function should not be available.
842	StringRef Extensions = FunctionExtensionTable[OpenCLBuiltin.Extension];
843	if (!Extensions.empty()) {
844	SmallVector<StringRef, 2> ExtVec;
845	Extensions.split(A&: ExtVec, Separator: " ");
846	bool AllExtensionsDefined = true;
847	for (StringRef Ext : ExtVec) {
848	if (!S.getPreprocessor().isMacroDefined(Id: Ext)) {
849	AllExtensionsDefined = false;
850	break;
851	}
852	}
853	if (!AllExtensionsDefined)
854	continue;
855	}
856
857	SmallVector<QualType, 1> RetTypes;
858	SmallVector<SmallVector<QualType, 1>, 5> ArgTypes;
859
860	// Obtain QualType lists for the function signature.
861	GetQualTypesForOpenCLBuiltin(S, OpenCLBuiltin, GenTypeMaxCnt, RetTypes,
862	ArgTypes);
863	if (GenTypeMaxCnt > 1) {
864	HasGenType = true;
865	}
866
867	// Create function overload for each type combination.
868	std::vector<QualType> FunctionList;
869	GetOpenCLBuiltinFctOverloads(Context, GenTypeMaxCnt, FunctionList, RetTypes,
870	ArgTypes);
871
872	SourceLocation Loc = LR.getNameLoc();
873	DeclContext *Parent = Context.getTranslationUnitDecl();
874	FunctionDecl *NewOpenCLBuiltin;
875
876	for (const auto &FTy : FunctionList) {
877	NewOpenCLBuiltin = FunctionDecl::Create(
878	C&: Context, DC: Parent, StartLoc: Loc, NLoc: Loc, N: II, T: FTy, /*TInfo=*/nullptr, SC: SC_Extern,
879	UsesFPIntrin: S.getCurFPFeatures().isFPConstrained(), isInlineSpecified: false,
880	hasWrittenPrototype: FTy->isFunctionProtoType());
881	NewOpenCLBuiltin->setImplicit();
882
883	// Create Decl objects for each parameter, adding them to the
884	// FunctionDecl.
885	const auto *FP = cast<FunctionProtoType>(Val: FTy);
886	SmallVector<ParmVarDecl *, 4> ParmList;
887	for (unsigned IParm = 0, e = FP->getNumParams(); IParm != e; ++IParm) {
888	ParmVarDecl *Parm = ParmVarDecl::Create(
889	Context, NewOpenCLBuiltin, SourceLocation(), SourceLocation(),
890	nullptr, FP->getParamType(i: IParm), nullptr, SC_None, nullptr);
891	Parm->setScopeInfo(scopeDepth: 0, parameterIndex: IParm);
892	ParmList.push_back(Elt: Parm);
893	}
894	NewOpenCLBuiltin->setParams(ParmList);
895
896	// Add function attributes.
897	if (OpenCLBuiltin.IsPure)
898	NewOpenCLBuiltin->addAttr(PureAttr::CreateImplicit(Context));
899	if (OpenCLBuiltin.IsConst)
900	NewOpenCLBuiltin->addAttr(ConstAttr::CreateImplicit(Context));
901	if (OpenCLBuiltin.IsConv)
902	NewOpenCLBuiltin->addAttr(ConvergentAttr::CreateImplicit(Context));
903
904	if (!S.getLangOpts().OpenCLCPlusPlus)
905	NewOpenCLBuiltin->addAttr(OverloadableAttr::CreateImplicit(Context));
906
907	LR.addDecl(NewOpenCLBuiltin);
908	}
909	}
910
911	// If we added overloads, need to resolve the lookup result.
912	if (Len > 1 || HasGenType)
913	LR.resolveKind();
914	}
915
916	/// Lookup a builtin function, when name lookup would otherwise
917	/// fail.
918	bool Sema::LookupBuiltin(LookupResult &R) {
919	Sema::LookupNameKind NameKind = R.getLookupKind();
920
921	// If we didn't find a use of this identifier, and if the identifier
922	// corresponds to a compiler builtin, create the decl object for the builtin
923	// now, injecting it into translation unit scope, and return it.
924	if (NameKind == Sema::LookupOrdinaryName ||
925	NameKind == Sema::LookupRedeclarationWithLinkage) {
926	IdentifierInfo *II = R.getLookupName().getAsIdentifierInfo();
927	if (II) {
928	if (getLangOpts().CPlusPlus && NameKind == Sema::LookupOrdinaryName) {
929	if (II == getASTContext().getMakeIntegerSeqName()) {
930	R.addDecl(getASTContext().getMakeIntegerSeqDecl());
931	return true;
932	} else if (II == getASTContext().getTypePackElementName()) {
933	R.addDecl(getASTContext().getTypePackElementDecl());
934	return true;
935	}
936	}
937
938	// Check if this is an OpenCL Builtin, and if so, insert its overloads.
939	if (getLangOpts().OpenCL && getLangOpts().DeclareOpenCLBuiltins) {
940	auto Index = isOpenCLBuiltin(II->getName());
941	if (Index.first) {
942	InsertOCLBuiltinDeclarationsFromTable(*this, R, II, Index.first - 1,
943	Index.second);
944	return true;
945	}
946	}
947
948	if (DeclareRISCVVBuiltins || DeclareRISCVSiFiveVectorBuiltins) {
949	if (!RVIntrinsicManager)
950	RVIntrinsicManager = CreateRISCVIntrinsicManager(S&: *this);
951
952	RVIntrinsicManager->InitIntrinsicList();
953
954	if (RVIntrinsicManager->CreateIntrinsicIfFound(LR&: R, II, PP))
955	return true;
956	}
957
958	// If this is a builtin on this (or all) targets, create the decl.
959	if (unsigned BuiltinID = II->getBuiltinID()) {
960	// In C++ and OpenCL (spec v1.2 s6.9.f), we don't have any predefined
961	// library functions like 'malloc'. Instead, we'll just error.
962	if ((getLangOpts().CPlusPlus || getLangOpts().OpenCL) &&
963	Context.BuiltinInfo.isPredefinedLibFunction(ID: BuiltinID))
964	return false;
965
966	if (NamedDecl *D =
967	LazilyCreateBuiltin(II, ID: BuiltinID, S: TUScope,
968	ForRedeclaration: R.isForRedeclaration(), Loc: R.getNameLoc())) {
969	R.addDecl(D);
970	return true;
971	}
972	}
973	}
974	}
975
976	return false;
977	}
978
979	/// Looks up the declaration of "struct objc_super" and
980	/// saves it for later use in building builtin declaration of
981	/// objc_msgSendSuper and objc_msgSendSuper_stret.
982	static void LookupPredefedObjCSuperType(Sema &Sema, Scope *S) {
983	ASTContext &Context = Sema.Context;
984	LookupResult Result(Sema, &Context.Idents.get(Name: "objc_super"), SourceLocation(),
985	Sema::LookupTagName);
986	Sema.LookupName(R&: Result, S);
987	if (Result.getResultKind() == LookupResult::Found)
988	if (const TagDecl *TD = Result.getAsSingle<TagDecl>())
989	Context.setObjCSuperType(Context.getTagDeclType(Decl: TD));
990	}
991
992	void Sema::LookupNecessaryTypesForBuiltin(Scope *S, unsigned ID) {
993	if (ID == Builtin::BIobjc_msgSendSuper)
994	LookupPredefedObjCSuperType(Sema&: *this, S);
995	}
996
997	/// Determine whether we can declare a special member function within
998	/// the class at this point.
999	static bool CanDeclareSpecialMemberFunction(const CXXRecordDecl *Class) {
1000	// We need to have a definition for the class.
1001	if (!Class->getDefinition() || Class->isDependentContext())
1002	return false;
1003
1004	// We can't be in the middle of defining the class.
1005	return !Class->isBeingDefined();
1006	}
1007
1008	void Sema::ForceDeclarationOfImplicitMembers(CXXRecordDecl *Class) {
1009	if (!CanDeclareSpecialMemberFunction(Class))
1010	return;
1011
1012	// If the default constructor has not yet been declared, do so now.
1013	if (Class->needsImplicitDefaultConstructor())
1014	DeclareImplicitDefaultConstructor(ClassDecl: Class);
1015
1016	// If the copy constructor has not yet been declared, do so now.
1017	if (Class->needsImplicitCopyConstructor())
1018	DeclareImplicitCopyConstructor(ClassDecl: Class);
1019
1020	// If the copy assignment operator has not yet been declared, do so now.
1021	if (Class->needsImplicitCopyAssignment())
1022	DeclareImplicitCopyAssignment(ClassDecl: Class);
1023
1024	if (getLangOpts().CPlusPlus11) {
1025	// If the move constructor has not yet been declared, do so now.
1026	if (Class->needsImplicitMoveConstructor())
1027	DeclareImplicitMoveConstructor(ClassDecl: Class);
1028
1029	// If the move assignment operator has not yet been declared, do so now.
1030	if (Class->needsImplicitMoveAssignment())
1031	DeclareImplicitMoveAssignment(ClassDecl: Class);
1032	}
1033
1034	// If the destructor has not yet been declared, do so now.
1035	if (Class->needsImplicitDestructor())
1036	DeclareImplicitDestructor(ClassDecl: Class);
1037	}
1038
1039	/// Determine whether this is the name of an implicitly-declared
1040	/// special member function.
1041	static bool isImplicitlyDeclaredMemberFunctionName(DeclarationName Name) {
1042	switch (Name.getNameKind()) {
1043	case DeclarationName::CXXConstructorName:
1044	case DeclarationName::CXXDestructorName:
1045	return true;
1046
1047	case DeclarationName::CXXOperatorName:
1048	return Name.getCXXOverloadedOperator() == OO_Equal;
1049
1050	default:
1051	break;
1052	}
1053
1054	return false;
1055	}
1056
1057	/// If there are any implicit member functions with the given name
1058	/// that need to be declared in the given declaration context, do so.
1059	static void DeclareImplicitMemberFunctionsWithName(Sema &S,
1060	DeclarationName Name,
1061	SourceLocation Loc,
1062	const DeclContext *DC) {
1063	if (!DC)
1064	return;
1065
1066	switch (Name.getNameKind()) {
1067	case DeclarationName::CXXConstructorName:
1068	if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Val: DC))
1069	if (Record->getDefinition() && CanDeclareSpecialMemberFunction(Class: Record)) {
1070	CXXRecordDecl *Class = const_cast<CXXRecordDecl *>(Record);
1071	if (Record->needsImplicitDefaultConstructor())
1072	S.DeclareImplicitDefaultConstructor(ClassDecl: Class);
1073	if (Record->needsImplicitCopyConstructor())
1074	S.DeclareImplicitCopyConstructor(ClassDecl: Class);
1075	if (S.getLangOpts().CPlusPlus11 &&
1076	Record->needsImplicitMoveConstructor())
1077	S.DeclareImplicitMoveConstructor(ClassDecl: Class);
1078	}
1079	break;
1080
1081	case DeclarationName::CXXDestructorName:
1082	if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Val: DC))
1083	if (Record->getDefinition() && Record->needsImplicitDestructor() &&
1084	CanDeclareSpecialMemberFunction(Class: Record))
1085	S.DeclareImplicitDestructor(ClassDecl: const_cast<CXXRecordDecl *>(Record));
1086	break;
1087
1088	case DeclarationName::CXXOperatorName:
1089	if (Name.getCXXOverloadedOperator() != OO_Equal)
1090	break;
1091
1092	if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Val: DC)) {
1093	if (Record->getDefinition() && CanDeclareSpecialMemberFunction(Class: Record)) {
1094	CXXRecordDecl *Class = const_cast<CXXRecordDecl *>(Record);
1095	if (Record->needsImplicitCopyAssignment())
1096	S.DeclareImplicitCopyAssignment(ClassDecl: Class);
1097	if (S.getLangOpts().CPlusPlus11 &&
1098	Record->needsImplicitMoveAssignment())
1099	S.DeclareImplicitMoveAssignment(ClassDecl: Class);
1100	}
1101	}
1102	break;
1103
1104	case DeclarationName::CXXDeductionGuideName:
1105	S.DeclareImplicitDeductionGuides(Template: Name.getCXXDeductionGuideTemplate(), Loc);
1106	break;
1107
1108	default:
1109	break;
1110	}
1111	}
1112
1113	// Adds all qualifying matches for a name within a decl context to the
1114	// given lookup result. Returns true if any matches were found.
1115	static bool LookupDirect(Sema &S, LookupResult &R, const DeclContext *DC) {
1116	bool Found = false;
1117
1118	// Lazily declare C++ special member functions.
1119	if (S.getLangOpts().CPlusPlus)
1120	DeclareImplicitMemberFunctionsWithName(S, Name: R.getLookupName(), Loc: R.getNameLoc(),
1121	DC);
1122
1123	// Perform lookup into this declaration context.
1124	DeclContext::lookup_result DR = DC->lookup(Name: R.getLookupName());
1125	for (NamedDecl *D : DR) {
1126	if ((D = R.getAcceptableDecl(D))) {
1127	R.addDecl(D);
1128	Found = true;
1129	}
1130	}
1131
1132	if (!Found && DC->isTranslationUnit() && S.LookupBuiltin(R))
1133	return true;
1134
1135	if (R.getLookupName().getNameKind()
1136	!= DeclarationName::CXXConversionFunctionName ||
1137	R.getLookupName().getCXXNameType()->isDependentType() ||
1138	!isa<CXXRecordDecl>(Val: DC))
1139	return Found;
1140
1141	// C++ [temp.mem]p6:
1142	// A specialization of a conversion function template is not found by
1143	// name lookup. Instead, any conversion function templates visible in the
1144	// context of the use are considered. [...]
1145	const CXXRecordDecl *Record = cast<CXXRecordDecl>(Val: DC);
1146	if (!Record->isCompleteDefinition())
1147	return Found;
1148
1149	// For conversion operators, 'operator auto' should only match
1150	// 'operator auto'. Since 'auto' is not a type, it shouldn't be considered
1151	// as a candidate for template substitution.
1152	auto *ContainedDeducedType =
1153	R.getLookupName().getCXXNameType()->getContainedDeducedType();
1154	if (R.getLookupName().getNameKind() ==
1155	DeclarationName::CXXConversionFunctionName &&
1156	ContainedDeducedType && ContainedDeducedType->isUndeducedType())
1157	return Found;
1158
1159	for (CXXRecordDecl::conversion_iterator U = Record->conversion_begin(),
1160	UEnd = Record->conversion_end(); U != UEnd; ++U) {
1161	FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(Val: *U);
1162	if (!ConvTemplate)
1163	continue;
1164
1165	// When we're performing lookup for the purposes of redeclaration, just
1166	// add the conversion function template. When we deduce template
1167	// arguments for specializations, we'll end up unifying the return
1168	// type of the new declaration with the type of the function template.
1169	if (R.isForRedeclaration()) {
1170	R.addDecl(ConvTemplate);
1171	Found = true;
1172	continue;
1173	}
1174
1175	// C++ [temp.mem]p6:
1176	// [...] For each such operator, if argument deduction succeeds
1177	// (14.9.2.3), the resulting specialization is used as if found by
1178	// name lookup.
1179	//
1180	// When referencing a conversion function for any purpose other than
1181	// a redeclaration (such that we'll be building an expression with the
1182	// result), perform template argument deduction and place the
1183	// specialization into the result set. We do this to avoid forcing all
1184	// callers to perform special deduction for conversion functions.
1185	TemplateDeductionInfo Info(R.getNameLoc());
1186	FunctionDecl *Specialization = nullptr;
1187
1188	const FunctionProtoType *ConvProto
1189	= ConvTemplate->getTemplatedDecl()->getType()->getAs<FunctionProtoType>();
1190	assert(ConvProto && "Nonsensical conversion function template type");
1191
1192	// Compute the type of the function that we would expect the conversion
1193	// function to have, if it were to match the name given.
1194	// FIXME: Calling convention!
1195	FunctionProtoType::ExtProtoInfo EPI = ConvProto->getExtProtoInfo();
1196	EPI.ExtInfo = EPI.ExtInfo.withCallingConv(cc: CC_C);
1197	EPI.ExceptionSpec = EST_None;
1198	QualType ExpectedType = R.getSema().Context.getFunctionType(
1199	ResultTy: R.getLookupName().getCXXNameType(), Args: std::nullopt, EPI);
1200
1201	// Perform template argument deduction against the type that we would
1202	// expect the function to have.
1203	if (R.getSema().DeduceTemplateArguments(FunctionTemplate: ConvTemplate, ExplicitTemplateArgs: nullptr, ArgFunctionType: ExpectedType,
1204	Specialization, Info) ==
1205	TemplateDeductionResult::Success) {
1206	R.addDecl(Specialization);
1207	Found = true;
1208	}
1209	}
1210
1211	return Found;
1212	}
1213
1214	// Performs C++ unqualified lookup into the given file context.
1215	static bool CppNamespaceLookup(Sema &S, LookupResult &R, ASTContext &Context,
1216	const DeclContext *NS,
1217	UnqualUsingDirectiveSet &UDirs) {
1218
1219	assert(NS && NS->isFileContext() && "CppNamespaceLookup() requires namespace!");
1220
1221	// Perform direct name lookup into the LookupCtx.
1222	bool Found = LookupDirect(S, R, DC: NS);
1223
1224	// Perform direct name lookup into the namespaces nominated by the
1225	// using directives whose common ancestor is this namespace.
1226	for (const UnqualUsingEntry &UUE : UDirs.getNamespacesFor(NS))
1227	if (LookupDirect(S, R, UUE.getNominatedNamespace()))
1228	Found = true;
1229
1230	R.resolveKind();
1231
1232	return Found;
1233	}
1234
1235	static bool isNamespaceOrTranslationUnitScope(Scope *S) {
1236	if (DeclContext *Ctx = S->getEntity())
1237	return Ctx->isFileContext();
1238	return false;
1239	}
1240
1241	/// Find the outer declaration context from this scope. This indicates the
1242	/// context that we should search up to (exclusive) before considering the
1243	/// parent of the specified scope.
1244	static DeclContext *findOuterContext(Scope *S) {
1245	for (Scope *OuterS = S->getParent(); OuterS; OuterS = OuterS->getParent())
1246	if (DeclContext *DC = OuterS->getLookupEntity())
1247	return DC;
1248	return nullptr;
1249	}
1250
1251	namespace {
1252	/// An RAII object to specify that we want to find block scope extern
1253	/// declarations.
1254	struct FindLocalExternScope {
1255	FindLocalExternScope(LookupResult &R)
1256	: R(R), OldFindLocalExtern(R.getIdentifierNamespace() &
1257	Decl::IDNS_LocalExtern) {
1258	R.setFindLocalExtern(R.getIdentifierNamespace() &
1259	(Decl::IDNS_Ordinary | Decl::IDNS_NonMemberOperator));
1260	}
1261	void restore() {
1262	R.setFindLocalExtern(OldFindLocalExtern);
1263	}
1264	~FindLocalExternScope() {
1265	restore();
1266	}
1267	LookupResult &R;
1268	bool OldFindLocalExtern;
1269	};
1270	} // end anonymous namespace
1271
1272	bool Sema::CppLookupName(LookupResult &R, Scope *S) {
1273	assert(getLangOpts().CPlusPlus && "Can perform only C++ lookup");
1274
1275	DeclarationName Name = R.getLookupName();
1276	Sema::LookupNameKind NameKind = R.getLookupKind();
1277
1278	// If this is the name of an implicitly-declared special member function,
1279	// go through the scope stack to implicitly declare
1280	if (isImplicitlyDeclaredMemberFunctionName(Name)) {
1281	for (Scope *PreS = S; PreS; PreS = PreS->getParent())
1282	if (DeclContext *DC = PreS->getEntity())
1283	DeclareImplicitMemberFunctionsWithName(S&: *this, Name, Loc: R.getNameLoc(), DC);
1284	}
1285
1286	// Implicitly declare member functions with the name we're looking for, if in
1287	// fact we are in a scope where it matters.
1288
1289	Scope *Initial = S;
1290	IdentifierResolver::iterator
1291	I = IdResolver.begin(Name),
1292	IEnd = IdResolver.end();
1293
1294	// First we lookup local scope.
1295	// We don't consider using-directives, as per 7.3.4.p1 [namespace.udir]
1296	// ...During unqualified name lookup (3.4.1), the names appear as if
1297	// they were declared in the nearest enclosing namespace which contains
1298	// both the using-directive and the nominated namespace.
1299	// [Note: in this context, "contains" means "contains directly or
1300	// indirectly".
1301	//
1302	// For example:
1303	// namespace A { int i; }
1304	// void foo() {
1305	// int i;
1306	// {
1307	// using namespace A;
1308	// ++i; // finds local 'i', A::i appears at global scope
1309	// }
1310	// }
1311	//
1312	UnqualUsingDirectiveSet UDirs(*this);
1313	bool VisitedUsingDirectives = false;
1314	bool LeftStartingScope = false;
1315
1316	// When performing a scope lookup, we want to find local extern decls.
1317	FindLocalExternScope FindLocals(R);
1318
1319	for (; S && !isNamespaceOrTranslationUnitScope(S); S = S->getParent()) {
1320	bool SearchNamespaceScope = true;
1321	// Check whether the IdResolver has anything in this scope.
1322	for (; I != IEnd && S->isDeclScope(*I); ++I) {
1323	if (NamedDecl *ND = R.getAcceptableDecl(D: *I)) {
1324	if (NameKind == LookupRedeclarationWithLinkage &&
1325	!(*I)->isTemplateParameter()) {
1326	// If it's a template parameter, we still find it, so we can diagnose
1327	// the invalid redeclaration.
1328
1329	// Determine whether this (or a previous) declaration is
1330	// out-of-scope.
1331	if (!LeftStartingScope && !Initial->isDeclScope(*I))
1332	LeftStartingScope = true;
1333
1334	// If we found something outside of our starting scope that
1335	// does not have linkage, skip it.
1336	if (LeftStartingScope && !((*I)->hasLinkage())) {
1337	R.setShadowed();
1338	continue;
1339	}
1340	} else {
1341	// We found something in this scope, we should not look at the
1342	// namespace scope
1343	SearchNamespaceScope = false;
1344	}
1345	R.addDecl(D: ND);
1346	}
1347	}
1348	if (!SearchNamespaceScope) {
1349	R.resolveKind();
1350	if (S->isClassScope())
1351	if (auto *Record = dyn_cast_if_present<CXXRecordDecl>(Val: S->getEntity()))
1352	R.setNamingClass(Record);
1353	return true;
1354	}
1355
1356	if (NameKind == LookupLocalFriendName && !S->isClassScope()) {
1357	// C++11 [class.friend]p11:
1358	// If a friend declaration appears in a local class and the name
1359	// specified is an unqualified name, a prior declaration is
1360	// looked up without considering scopes that are outside the
1361	// innermost enclosing non-class scope.
1362	return false;
1363	}
1364
1365	if (DeclContext *Ctx = S->getLookupEntity()) {
1366	DeclContext *OuterCtx = findOuterContext(S);
1367	for (; Ctx && !Ctx->Equals(DC: OuterCtx); Ctx = Ctx->getLookupParent()) {
1368	// We do not directly look into transparent contexts, since
1369	// those entities will be found in the nearest enclosing
1370	// non-transparent context.
1371	if (Ctx->isTransparentContext())
1372	continue;
1373
1374	// We do not look directly into function or method contexts,
1375	// since all of the local variables and parameters of the
1376	// function/method are present within the Scope.
1377	if (Ctx->isFunctionOrMethod()) {
1378	// If we have an Objective-C instance method, look for ivars
1379	// in the corresponding interface.
1380	if (ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(Val: Ctx)) {
1381	if (Method->isInstanceMethod() && Name.getAsIdentifierInfo())
1382	if (ObjCInterfaceDecl *Class = Method->getClassInterface()) {
1383	ObjCInterfaceDecl *ClassDeclared;
1384	if (ObjCIvarDecl *Ivar = Class->lookupInstanceVariable(
1385	IVarName: Name.getAsIdentifierInfo(),
1386	ClassDeclared)) {
1387	if (NamedDecl *ND = R.getAcceptableDecl(Ivar)) {
1388	R.addDecl(D: ND);
1389	R.resolveKind();
1390	return true;
1391	}
1392	}
1393	}
1394	}
1395
1396	continue;
1397	}
1398
1399	// If this is a file context, we need to perform unqualified name
1400	// lookup considering using directives.
1401	if (Ctx->isFileContext()) {
1402	// If we haven't handled using directives yet, do so now.
1403	if (!VisitedUsingDirectives) {
1404	// Add using directives from this context up to the top level.
1405	for (DeclContext *UCtx = Ctx; UCtx; UCtx = UCtx->getParent()) {
1406	if (UCtx->isTransparentContext())
1407	continue;
1408
1409	UDirs.visit(DC: UCtx, EffectiveDC: UCtx);
1410	}
1411
1412	// Find the innermost file scope, so we can add using directives
1413	// from local scopes.
1414	Scope *InnermostFileScope = S;
1415	while (InnermostFileScope &&
1416	!isNamespaceOrTranslationUnitScope(S: InnermostFileScope))
1417	InnermostFileScope = InnermostFileScope->getParent();
1418	UDirs.visitScopeChain(S: Initial, InnermostFileScope);
1419
1420	UDirs.done();
1421
1422	VisitedUsingDirectives = true;
1423	}
1424
1425	if (CppNamespaceLookup(S&: *this, R, Context, NS: Ctx, UDirs)) {
1426	R.resolveKind();
1427	return true;
1428	}
1429
1430	continue;
1431	}
1432
1433	// Perform qualified name lookup into this context.
1434	// FIXME: In some cases, we know that every name that could be found by
1435	// this qualified name lookup will also be on the identifier chain. For
1436	// example, inside a class without any base classes, we never need to
1437	// perform qualified lookup because all of the members are on top of the
1438	// identifier chain.
1439	if (LookupQualifiedName(R, LookupCtx: Ctx, /*InUnqualifiedLookup=*/true))
1440	return true;
1441	}
1442	}
1443	}
1444
1445	// Stop if we ran out of scopes.
1446	// FIXME: This really, really shouldn't be happening.
1447	if (!S) return false;
1448
1449	// If we are looking for members, no need to look into global/namespace scope.
1450	if (NameKind == LookupMemberName)
1451	return false;
1452
1453	// Collect UsingDirectiveDecls in all scopes, and recursively all
1454	// nominated namespaces by those using-directives.
1455	//
1456	// FIXME: Cache this sorted list in Scope structure, and DeclContext, so we
1457	// don't build it for each lookup!
1458	if (!VisitedUsingDirectives) {
1459	UDirs.visitScopeChain(S: Initial, InnermostFileScope: S);
1460	UDirs.done();
1461	}
1462
1463	// If we're not performing redeclaration lookup, do not look for local
1464	// extern declarations outside of a function scope.
1465	if (!R.isForRedeclaration())
1466	FindLocals.restore();
1467
1468	// Lookup namespace scope, and global scope.
1469	// Unqualified name lookup in C++ requires looking into scopes
1470	// that aren't strictly lexical, and therefore we walk through the
1471	// context as well as walking through the scopes.
1472	for (; S; S = S->getParent()) {
1473	// Check whether the IdResolver has anything in this scope.
1474	bool Found = false;
1475	for (; I != IEnd && S->isDeclScope(*I); ++I) {
1476	if (NamedDecl *ND = R.getAcceptableDecl(D: *I)) {
1477	// We found something. Look for anything else in our scope
1478	// with this same name and in an acceptable identifier
1479	// namespace, so that we can construct an overload set if we
1480	// need to.
1481	Found = true;
1482	R.addDecl(D: ND);
1483	}
1484	}
1485
1486	if (Found && S->isTemplateParamScope()) {
1487	R.resolveKind();
1488	return true;
1489	}
1490
1491	DeclContext *Ctx = S->getLookupEntity();
1492	if (Ctx) {
1493	DeclContext *OuterCtx = findOuterContext(S);
1494	for (; Ctx && !Ctx->Equals(DC: OuterCtx); Ctx = Ctx->getLookupParent()) {
1495	// We do not directly look into transparent contexts, since
1496	// those entities will be found in the nearest enclosing
1497	// non-transparent context.
1498	if (Ctx->isTransparentContext())
1499	continue;
1500
1501	// If we have a context, and it's not a context stashed in the
1502	// template parameter scope for an out-of-line definition, also
1503	// look into that context.
1504	if (!(Found && S->isTemplateParamScope())) {
1505	assert(Ctx->isFileContext() &&
1506	"We should have been looking only at file context here already.");
1507
1508	// Look into context considering using-directives.
1509	if (CppNamespaceLookup(S&: *this, R, Context, NS: Ctx, UDirs))
1510	Found = true;
1511	}
1512
1513	if (Found) {
1514	R.resolveKind();
1515	return true;
1516	}
1517
1518	if (R.isForRedeclaration() && !Ctx->isTransparentContext())
1519	return false;
1520	}
1521	}
1522
1523	if (R.isForRedeclaration() && Ctx && !Ctx->isTransparentContext())
1524	return false;
1525	}
1526
1527	return !R.empty();
1528	}
1529
1530	void Sema::makeMergedDefinitionVisible(NamedDecl *ND) {
1531	if (auto *M = getCurrentModule())
1532	Context.mergeDefinitionIntoModule(ND, M);
1533	else
1534	// We're not building a module; just make the definition visible.
1535	ND->setVisibleDespiteOwningModule();
1536
1537	// If ND is a template declaration, make the template parameters
1538	// visible too. They're not (necessarily) within a mergeable DeclContext.
1539	if (auto *TD = dyn_cast<TemplateDecl>(Val: ND))
1540	for (auto *Param : *TD->getTemplateParameters())
1541	makeMergedDefinitionVisible(ND: Param);
1542	}
1543
1544	/// Find the module in which the given declaration was defined.
1545	static Module *getDefiningModule(Sema &S, Decl *Entity) {
1546	if (FunctionDecl *FD = dyn_cast<FunctionDecl>(Val: Entity)) {
1547	// If this function was instantiated from a template, the defining module is
1548	// the module containing the pattern.
1549	if (FunctionDecl *Pattern = FD->getTemplateInstantiationPattern())
1550	Entity = Pattern;
1551	} else if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Val: Entity)) {
1552	if (CXXRecordDecl *Pattern = RD->getTemplateInstantiationPattern())
1553	Entity = Pattern;
1554	} else if (EnumDecl *ED = dyn_cast<EnumDecl>(Val: Entity)) {
1555	if (auto *Pattern = ED->getTemplateInstantiationPattern())
1556	Entity = Pattern;
1557	} else if (VarDecl *VD = dyn_cast<VarDecl>(Val: Entity)) {
1558	if (VarDecl *Pattern = VD->getTemplateInstantiationPattern())
1559	Entity = Pattern;
1560	}
1561
1562	// Walk up to the containing context. That might also have been instantiated
1563	// from a template.
1564	DeclContext *Context = Entity->getLexicalDeclContext();
1565	if (Context->isFileContext())
1566	return S.getOwningModule(Entity);
1567	return getDefiningModule(S, Entity: cast<Decl>(Val: Context));
1568	}
1569
1570	llvm::DenseSet<Module*> &Sema::getLookupModules() {
1571	unsigned N = CodeSynthesisContexts.size();
1572	for (unsigned I = CodeSynthesisContextLookupModules.size();
1573	I != N; ++I) {
1574	Module *M = CodeSynthesisContexts[I].Entity ?
1575	getDefiningModule(S&: *this, Entity: CodeSynthesisContexts[I].Entity) :
1576	nullptr;
1577	if (M && !LookupModulesCache.insert(V: M).second)
1578	M = nullptr;
1579	CodeSynthesisContextLookupModules.push_back(Elt: M);
1580	}
1581	return LookupModulesCache;
1582	}
1583
1584	/// Determine if we could use all the declarations in the module.
1585	bool Sema::isUsableModule(const Module *M) {
1586	assert(M && "We shouldn't check nullness for module here");
1587	// Return quickly if we cached the result.
1588	if (UsableModuleUnitsCache.count(V: M))
1589	return true;
1590
1591	// If M is the global module fragment of the current translation unit. So it
1592	// should be usable.
1593	// [module.global.frag]p1:
1594	// The global module fragment can be used to provide declarations that are
1595	// attached to the global module and usable within the module unit.
1596	if (M == TheGlobalModuleFragment || M == TheImplicitGlobalModuleFragment ||
1597	// If M is the module we're parsing, it should be usable. This covers the
1598	// private module fragment. The private module fragment is usable only if
1599	// it is within the current module unit. And it must be the current
1600	// parsing module unit if it is within the current module unit according
1601	// to the grammar of the private module fragment. NOTE: This is covered by
1602	// the following condition. The intention of the check is to avoid string
1603	// comparison as much as possible.
1604	M == getCurrentModule() ||
1605	// The module unit which is in the same module with the current module
1606	// unit is usable.
1607	//
1608	// FIXME: Here we judge if they are in the same module by comparing the
1609	// string. Is there any better solution?
1610	M->getPrimaryModuleInterfaceName() ==
1611	llvm::StringRef(getLangOpts().CurrentModule).split(Separator: ':').first) {
1612	UsableModuleUnitsCache.insert(V: M);
1613	return true;
1614	}
1615
1616	return false;
1617	}
1618
1619	bool Sema::hasVisibleMergedDefinition(const NamedDecl *Def) {
1620	for (const Module *Merged : Context.getModulesWithMergedDefinition(Def))
1621	if (isModuleVisible(M: Merged))
1622	return true;
1623	return false;
1624	}
1625
1626	bool Sema::hasMergedDefinitionInCurrentModule(const NamedDecl *Def) {
1627	for (const Module *Merged : Context.getModulesWithMergedDefinition(Def))
1628	if (isUsableModule(M: Merged))
1629	return true;
1630	return false;
1631	}
1632
1633	template <typename ParmDecl>
1634	static bool
1635	hasAcceptableDefaultArgument(Sema &S, const ParmDecl *D,
1636	llvm::SmallVectorImpl<Module *> *Modules,
1637	Sema::AcceptableKind Kind) {
1638	if (!D->hasDefaultArgument())
1639	return false;
1640
1641	llvm::SmallPtrSet<const ParmDecl *, 4> Visited;
1642	while (D && Visited.insert(D).second) {
1643	auto &DefaultArg = D->getDefaultArgStorage();
1644	if (!DefaultArg.isInherited() && S.isAcceptable(D, Kind))
1645	return true;
1646
1647	if (!DefaultArg.isInherited() && Modules) {
1648	auto *NonConstD = const_cast<ParmDecl*>(D);
1649	Modules->push_back(Elt: S.getOwningModule(Entity: NonConstD));
1650	}
1651
1652	// If there was a previous default argument, maybe its parameter is
1653	// acceptable.
1654	D = DefaultArg.getInheritedFrom();
1655	}
1656	return false;
1657	}
1658
1659	bool Sema::hasAcceptableDefaultArgument(
1660	const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules,
1661	Sema::AcceptableKind Kind) {
1662	if (auto *P = dyn_cast<TemplateTypeParmDecl>(Val: D))
1663	return ::hasAcceptableDefaultArgument(S&: *this, D: P, Modules, Kind);
1664
1665	if (auto *P = dyn_cast<NonTypeTemplateParmDecl>(Val: D))
1666	return ::hasAcceptableDefaultArgument(S&: *this, D: P, Modules, Kind);
1667
1668	return ::hasAcceptableDefaultArgument(
1669	S&: *this, D: cast<TemplateTemplateParmDecl>(Val: D), Modules, Kind);
1670	}
1671
1672	bool Sema::hasVisibleDefaultArgument(const NamedDecl *D,
1673	llvm::SmallVectorImpl<Module *> *Modules) {
1674	return hasAcceptableDefaultArgument(D, Modules,
1675	Kind: Sema::AcceptableKind::Visible);
1676	}
1677
1678	bool Sema::hasReachableDefaultArgument(
1679	const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
1680	return hasAcceptableDefaultArgument(D, Modules,
1681	Kind: Sema::AcceptableKind::Reachable);
1682	}
1683
1684	template <typename Filter>
1685	static bool
1686	hasAcceptableDeclarationImpl(Sema &S, const NamedDecl *D,
1687	llvm::SmallVectorImpl<Module *> *Modules, Filter F,
1688	Sema::AcceptableKind Kind) {
1689	bool HasFilteredRedecls = false;
1690
1691	for (auto *Redecl : D->redecls()) {
1692	auto *R = cast<NamedDecl>(Redecl);
1693	if (!F(R))
1694	continue;
1695
1696	if (S.isAcceptable(R, Kind))
1697	return true;
1698
1699	HasFilteredRedecls = true;
1700
1701	if (Modules)
1702	Modules->push_back(R->getOwningModule());
1703	}
1704
1705	// Only return false if there is at least one redecl that is not filtered out.
1706	if (HasFilteredRedecls)
1707	return false;
1708
1709	return true;
1710	}
1711
1712	static bool
1713	hasAcceptableExplicitSpecialization(Sema &S, const NamedDecl *D,
1714	llvm::SmallVectorImpl<Module *> *Modules,
1715	Sema::AcceptableKind Kind) {
1716	return hasAcceptableDeclarationImpl(
1717	S, D, Modules,
1718	F: [](const NamedDecl *D) {
1719	if (auto *RD = dyn_cast<CXXRecordDecl>(Val: D))
1720	return RD->getTemplateSpecializationKind() ==
1721	TSK_ExplicitSpecialization;
1722	if (auto *FD = dyn_cast<FunctionDecl>(Val: D))
1723	return FD->getTemplateSpecializationKind() ==
1724	TSK_ExplicitSpecialization;
1725	if (auto *VD = dyn_cast<VarDecl>(Val: D))
1726	return VD->getTemplateSpecializationKind() ==
1727	TSK_ExplicitSpecialization;
1728	llvm_unreachable("unknown explicit specialization kind");
1729	},
1730	Kind);
1731	}
1732
1733	bool Sema::hasVisibleExplicitSpecialization(
1734	const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
1735	return ::hasAcceptableExplicitSpecialization(S&: *this, D, Modules,
1736	Kind: Sema::AcceptableKind::Visible);
1737	}
1738
1739	bool Sema::hasReachableExplicitSpecialization(
1740	const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
1741	return ::hasAcceptableExplicitSpecialization(S&: *this, D, Modules,
1742	Kind: Sema::AcceptableKind::Reachable);
1743	}
1744
1745	static bool
1746	hasAcceptableMemberSpecialization(Sema &S, const NamedDecl *D,
1747	llvm::SmallVectorImpl<Module *> *Modules,
1748	Sema::AcceptableKind Kind) {
1749	assert(isa<CXXRecordDecl>(D->getDeclContext()) &&
1750	"not a member specialization");
1751	return hasAcceptableDeclarationImpl(
1752	S, D, Modules,
1753	F: [](const NamedDecl *D) {
1754	// If the specialization is declared at namespace scope, then it's a
1755	// member specialization declaration. If it's lexically inside the class
1756	// definition then it was instantiated.
1757	//
1758	// FIXME: This is a hack. There should be a better way to determine
1759	// this.
1760	// FIXME: What about MS-style explicit specializations declared within a
1761	// class definition?
1762	return D->getLexicalDeclContext()->isFileContext();
1763	},
1764	Kind);
1765	}
1766
1767	bool Sema::hasVisibleMemberSpecialization(
1768	const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
1769	return hasAcceptableMemberSpecialization(S&: *this, D, Modules,
1770	Kind: Sema::AcceptableKind::Visible);
1771	}
1772
1773	bool Sema::hasReachableMemberSpecialization(
1774	const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
1775	return hasAcceptableMemberSpecialization(S&: *this, D, Modules,
1776	Kind: Sema::AcceptableKind::Reachable);
1777	}
1778
1779	/// Determine whether a declaration is acceptable to name lookup.
1780	///
1781	/// This routine determines whether the declaration D is acceptable in the
1782	/// current lookup context, taking into account the current template
1783	/// instantiation stack. During template instantiation, a declaration is
1784	/// acceptable if it is acceptable from a module containing any entity on the
1785	/// template instantiation path (by instantiating a template, you allow it to
1786	/// see the declarations that your module can see, including those later on in
1787	/// your module).
1788	bool LookupResult::isAcceptableSlow(Sema &SemaRef, NamedDecl *D,
1789	Sema::AcceptableKind Kind) {
1790	assert(!D->isUnconditionallyVisible() &&
1791	"should not call this: not in slow case");
1792
1793	Module *DeclModule = SemaRef.getOwningModule(D);
1794	assert(DeclModule && "hidden decl has no owning module");
1795
1796	// If the owning module is visible, the decl is acceptable.
1797	if (SemaRef.isModuleVisible(M: DeclModule,
1798	ModulePrivate: D->isInvisibleOutsideTheOwningModule()))
1799	return true;
1800
1801	// Determine whether a decl context is a file context for the purpose of
1802	// visibility/reachability. This looks through some (export and linkage spec)
1803	// transparent contexts, but not others (enums).
1804	auto IsEffectivelyFileContext = [](const DeclContext *DC) {
1805	return DC->isFileContext() || isa<LinkageSpecDecl>(Val: DC) ||
1806	isa<ExportDecl>(Val: DC);
1807	};
1808
1809	// If this declaration is not at namespace scope
1810	// then it is acceptable if its lexical parent has a acceptable definition.
1811	DeclContext *DC = D->getLexicalDeclContext();
1812	if (DC && !IsEffectivelyFileContext(DC)) {
1813	// For a parameter, check whether our current template declaration's
1814	// lexical context is acceptable, not whether there's some other acceptable
1815	// definition of it, because parameters aren't "within" the definition.
1816	//
1817	// In C++ we need to check for a acceptable definition due to ODR merging,
1818	// and in C we must not because each declaration of a function gets its own
1819	// set of declarations for tags in prototype scope.
1820	bool AcceptableWithinParent;
1821	if (D->isTemplateParameter()) {
1822	bool SearchDefinitions = true;
1823	if (const auto *DCD = dyn_cast<Decl>(DC)) {
1824	if (const auto *TD = DCD->getDescribedTemplate()) {
1825	TemplateParameterList *TPL = TD->getTemplateParameters();
1826	auto Index = getDepthAndIndex(ND: D).second;
1827	SearchDefinitions = Index >= TPL->size() || TPL->getParam(Idx: Index) != D;
1828	}
1829	}
1830	if (SearchDefinitions)
1831	AcceptableWithinParent =
1832	SemaRef.hasAcceptableDefinition(D: cast<NamedDecl>(Val: DC), Kind);
1833	else
1834	AcceptableWithinParent =
1835	isAcceptable(SemaRef, D: cast<NamedDecl>(Val: DC), Kind);
1836	} else if (isa<ParmVarDecl>(Val: D) ||
1837	(isa<FunctionDecl>(Val: DC) && !SemaRef.getLangOpts().CPlusPlus))
1838	AcceptableWithinParent = isAcceptable(SemaRef, D: cast<NamedDecl>(Val: DC), Kind);
1839	else if (D->isModulePrivate()) {
1840	// A module-private declaration is only acceptable if an enclosing lexical
1841	// parent was merged with another definition in the current module.
1842	AcceptableWithinParent = false;
1843	do {
1844	if (SemaRef.hasMergedDefinitionInCurrentModule(Def: cast<NamedDecl>(Val: DC))) {
1845	AcceptableWithinParent = true;
1846	break;
1847	}
1848	DC = DC->getLexicalParent();
1849	} while (!IsEffectivelyFileContext(DC));
1850	} else {
1851	AcceptableWithinParent =
1852	SemaRef.hasAcceptableDefinition(D: cast<NamedDecl>(Val: DC), Kind);
1853	}
1854
1855	if (AcceptableWithinParent && SemaRef.CodeSynthesisContexts.empty() &&
1856	Kind == Sema::AcceptableKind::Visible &&
1857	// FIXME: Do something better in this case.
1858	!SemaRef.getLangOpts().ModulesLocalVisibility) {
1859	// Cache the fact that this declaration is implicitly visible because
1860	// its parent has a visible definition.
1861	D->setVisibleDespiteOwningModule();
1862	}
1863	return AcceptableWithinParent;
1864	}
1865
1866	if (Kind == Sema::AcceptableKind::Visible)
1867	return false;
1868
1869	assert(Kind == Sema::AcceptableKind::Reachable &&
1870	"Additional Sema::AcceptableKind?");
1871	return isReachableSlow(SemaRef, D);
1872	}
1873
1874	bool Sema::isModuleVisible(const Module *M, bool ModulePrivate) {
1875	// The module might be ordinarily visible. For a module-private query, that
1876	// means it is part of the current module.
1877	if (ModulePrivate && isUsableModule(M))
1878	return true;
1879
1880	// For a query which is not module-private, that means it is in our visible
1881	// module set.
1882	if (!ModulePrivate && VisibleModules.isVisible(M))
1883	return true;
1884
1885	// Otherwise, it might be visible by virtue of the query being within a
1886	// template instantiation or similar that is permitted to look inside M.
1887
1888	// Find the extra places where we need to look.
1889	const auto &LookupModules = getLookupModules();
1890	if (LookupModules.empty())
1891	return false;
1892
1893	// If our lookup set contains the module, it's visible.
1894	if (LookupModules.count(V: M))
1895	return true;
1896
1897	// The global module fragments are visible to its corresponding module unit.
1898	// So the global module fragment should be visible if the its corresponding
1899	// module unit is visible.
1900	if (M->isGlobalModule() && LookupModules.count(V: M->getTopLevelModule()))
1901	return true;
1902
1903	// For a module-private query, that's everywhere we get to look.
1904	if (ModulePrivate)
1905	return false;
1906
1907	// Check whether M is transitively exported to an import of the lookup set.
1908	return llvm::any_of(Range: LookupModules, P: [&](const Module *LookupM) {
1909	return LookupM->isModuleVisible(M);
1910	});
1911	}
1912
1913	// FIXME: Return false directly if we don't have an interface dependency on the
1914	// translation unit containing D.
1915	bool LookupResult::isReachableSlow(Sema &SemaRef, NamedDecl *D) {
1916	assert(!isVisible(SemaRef, D) && "Shouldn't call the slow case.\n");
1917
1918	Module *DeclModule = SemaRef.getOwningModule(D);
1919	assert(DeclModule && "hidden decl has no owning module");
1920
1921	// Entities in header like modules are reachable only if they're visible.
1922	if (DeclModule->isHeaderLikeModule())
1923	return false;
1924
1925	if (!D->isInAnotherModuleUnit())
1926	return true;
1927
1928	// [module.reach]/p3:
1929	// A declaration D is reachable from a point P if:
1930	// ...
1931	// - D is not discarded ([module.global.frag]), appears in a translation unit
1932	// that is reachable from P, and does not appear within a private module
1933	// fragment.
1934	//
1935	// A declaration that's discarded in the GMF should be module-private.
1936	if (D->isModulePrivate())
1937	return false;
1938
1939	// [module.reach]/p1
1940	// A translation unit U is necessarily reachable from a point P if U is a
1941	// module interface unit on which the translation unit containing P has an
1942	// interface dependency, or the translation unit containing P imports U, in
1943	// either case prior to P ([module.import]).
1944	//
1945	// [module.import]/p10
1946	// A translation unit has an interface dependency on a translation unit U if
1947	// it contains a declaration (possibly a module-declaration) that imports U
1948	// or if it has an interface dependency on a translation unit that has an
1949	// interface dependency on U.
1950	//
1951	// So we could conclude the module unit U is necessarily reachable if:
1952	// (1) The module unit U is module interface unit.
1953	// (2) The current unit has an interface dependency on the module unit U.
1954	//
1955	// Here we only check for the first condition. Since we couldn't see
1956	// DeclModule if it isn't (transitively) imported.
1957	if (DeclModule->getTopLevelModule()->isModuleInterfaceUnit())
1958	return true;
1959
1960	// [module.reach]/p2
1961	// Additional translation units on
1962	// which the point within the program has an interface dependency may be
1963	// considered reachable, but it is unspecified which are and under what
1964	// circumstances.
1965	//
1966	// The decision here is to treat all additional tranditional units as
1967	// unreachable.
1968	return false;
1969	}
1970
1971	bool Sema::isAcceptableSlow(const NamedDecl *D, Sema::AcceptableKind Kind) {
1972	return LookupResult::isAcceptable(SemaRef&: *this, D: const_cast<NamedDecl *>(D), Kind);
1973	}
1974
1975	bool Sema::shouldLinkPossiblyHiddenDecl(LookupResult &R, const NamedDecl *New) {
1976	// FIXME: If there are both visible and hidden declarations, we need to take
1977	// into account whether redeclaration is possible. Example:
1978	//
1979	// Non-imported module:
1980	// int f(T); // #1
1981	// Some TU:
1982	// static int f(U); // #2, not a redeclaration of #1
1983	// int f(T); // #3, finds both, should link with #1 if T != U, but
1984	// // with #2 if T == U; neither should be ambiguous.
1985	for (auto *D : R) {
1986	if (isVisible(D))
1987	return true;
1988	assert(D->isExternallyDeclarable() &&
1989	"should not have hidden, non-externally-declarable result here");
1990	}
1991
1992	// This function is called once "New" is essentially complete, but before a
1993	// previous declaration is attached. We can't query the linkage of "New" in
1994	// general, because attaching the previous declaration can change the
1995	// linkage of New to match the previous declaration.
1996	//
1997	// However, because we've just determined that there is no *visible* prior
1998	// declaration, we can compute the linkage here. There are two possibilities:
1999	//
2000	// * This is not a redeclaration; it's safe to compute the linkage now.
2001	//
2002	// * This is a redeclaration of a prior declaration that is externally
2003	// redeclarable. In that case, the linkage of the declaration is not
2004	// changed by attaching the prior declaration, because both are externally
2005	// declarable (and thus ExternalLinkage or VisibleNoLinkage).
2006	//
2007	// FIXME: This is subtle and fragile.
2008	return New->isExternallyDeclarable();
2009	}
2010
2011	/// Retrieve the visible declaration corresponding to D, if any.
2012	///
2013	/// This routine determines whether the declaration D is visible in the current
2014	/// module, with the current imports. If not, it checks whether any
2015	/// redeclaration of D is visible, and if so, returns that declaration.
2016	///
2017	/// \returns D, or a visible previous declaration of D, whichever is more recent
2018	/// and visible. If no declaration of D is visible, returns null.
2019	static NamedDecl *findAcceptableDecl(Sema &SemaRef, NamedDecl *D,
2020	unsigned IDNS) {
2021	assert(!LookupResult::isAvailableForLookup(SemaRef, D) && "not in slow case");
2022
2023	for (auto *RD : D->redecls()) {
2024	// Don't bother with extra checks if we already know this one isn't visible.
2025	if (RD == D)
2026	continue;
2027
2028	auto ND = cast<NamedDecl>(RD);
2029	// FIXME: This is wrong in the case where the previous declaration is not
2030	// visible in the same scope as D. This needs to be done much more
2031	// carefully.
2032	if (ND->isInIdentifierNamespace(IDNS) &&
2033	LookupResult::isAvailableForLookup(SemaRef, ND))
2034	return ND;
2035	}
2036
2037	return nullptr;
2038	}
2039
2040	bool Sema::hasVisibleDeclarationSlow(const NamedDecl *D,
2041	llvm::SmallVectorImpl<Module *> *Modules) {
2042	assert(!isVisible(D) && "not in slow case");
2043	return hasAcceptableDeclarationImpl(
2044	S&: *this, D, Modules, F: [](const NamedDecl *) { return true; },
2045	Kind: Sema::AcceptableKind::Visible);
2046	}
2047
2048	bool Sema::hasReachableDeclarationSlow(
2049	const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
2050	assert(!isReachable(D) && "not in slow case");
2051	return hasAcceptableDeclarationImpl(
2052	S&: *this, D, Modules, F: [](const NamedDecl *) { return true; },
2053	Kind: Sema::AcceptableKind::Reachable);
2054	}
2055
2056	NamedDecl *LookupResult::getAcceptableDeclSlow(NamedDecl *D) const {
2057	if (auto *ND = dyn_cast<NamespaceDecl>(Val: D)) {
2058	// Namespaces are a bit of a special case: we expect there to be a lot of
2059	// redeclarations of some namespaces, all declarations of a namespace are
2060	// essentially interchangeable, all declarations are found by name lookup
2061	// if any is, and namespaces are never looked up during template
2062	// instantiation. So we benefit from caching the check in this case, and
2063	// it is correct to do so.
2064	auto *Key = ND->getCanonicalDecl();
2065	if (auto *Acceptable = getSema().VisibleNamespaceCache.lookup(Key))
2066	return Acceptable;
2067	auto *Acceptable = isVisible(getSema(), Key)
2068	? Key
2069	: findAcceptableDecl(getSema(), Key, IDNS);
2070	if (Acceptable)
2071	getSema().VisibleNamespaceCache.insert(std::make_pair(Key, Acceptable));
2072	return Acceptable;
2073	}
2074
2075	return findAcceptableDecl(SemaRef&: getSema(), D, IDNS);
2076	}
2077
2078	bool LookupResult::isVisible(Sema &SemaRef, NamedDecl *D) {
2079	// If this declaration is already visible, return it directly.
2080	if (D->isUnconditionallyVisible())
2081	return true;
2082
2083	// During template instantiation, we can refer to hidden declarations, if
2084	// they were visible in any module along the path of instantiation.
2085	return isAcceptableSlow(SemaRef, D, Kind: Sema::AcceptableKind::Visible);
2086	}
2087
2088	bool LookupResult::isReachable(Sema &SemaRef, NamedDecl *D) {
2089	if (D->isUnconditionallyVisible())
2090	return true;
2091
2092	return isAcceptableSlow(SemaRef, D, Kind: Sema::AcceptableKind::Reachable);
2093	}
2094
2095	bool LookupResult::isAvailableForLookup(Sema &SemaRef, NamedDecl *ND) {
2096	// We should check the visibility at the callsite already.
2097	if (isVisible(SemaRef, D: ND))
2098	return true;
2099
2100	// Deduction guide lives in namespace scope generally, but it is just a
2101	// hint to the compilers. What we actually lookup for is the generated member
2102	// of the corresponding template. So it is sufficient to check the
2103	// reachability of the template decl.
2104	if (auto *DeductionGuide = ND->getDeclName().getCXXDeductionGuideTemplate())
2105	return SemaRef.hasReachableDefinition(DeductionGuide);
2106
2107	// FIXME: The lookup for allocation function is a standalone process.
2108	// (We can find the logics in Sema::FindAllocationFunctions)
2109	//
2110	// Such structure makes it a problem when we instantiate a template
2111	// declaration using placement allocation function if the placement
2112	// allocation function is invisible.
2113	// (See https://github.com/llvm/llvm-project/issues/59601)
2114	//
2115	// Here we workaround it by making the placement allocation functions
2116	// always acceptable. The downside is that we can't diagnose the direct
2117	// use of the invisible placement allocation functions. (Although such uses
2118	// should be rare).
2119	if (auto *FD = dyn_cast<FunctionDecl>(Val: ND);
2120	FD && FD->isReservedGlobalPlacementOperator())
2121	return true;
2122
2123	auto *DC = ND->getDeclContext();
2124	// If ND is not visible and it is at namespace scope, it shouldn't be found
2125	// by name lookup.
2126	if (DC->isFileContext())
2127	return false;
2128
2129	// [module.interface]p7
2130	// Class and enumeration member names can be found by name lookup in any
2131	// context in which a definition of the type is reachable.
2132	//
2133	// FIXME: The current implementation didn't consider about scope. For example,
2134	// ```
2135	// // m.cppm
2136	// export module m;
2137	// enum E1 { e1 };
2138	// // Use.cpp
2139	// import m;
2140	// void test() {
2141	// auto a = E1::e1; // Error as expected.
2142	// auto b = e1; // Should be error. namespace-scope name e1 is not visible
2143	// }
2144	// ```
2145	// For the above example, the current implementation would emit error for `a`
2146	// correctly. However, the implementation wouldn't diagnose about `b` now.
2147	// Since we only check the reachability for the parent only.
2148	// See clang/test/CXX/module/module.interface/p7.cpp for example.
2149	if (auto *TD = dyn_cast<TagDecl>(DC))
2150	return SemaRef.hasReachableDefinition(TD);
2151
2152	return false;
2153	}
2154
2155	/// Perform unqualified name lookup starting from a given
2156	/// scope.
2157	///
2158	/// Unqualified name lookup (C++ [basic.lookup.unqual], C99 6.2.1) is
2159	/// used to find names within the current scope. For example, 'x' in
2160	/// @code
2161	/// int x;
2162	/// int f() {
2163	/// return x; // unqualified name look finds 'x' in the global scope
2164	/// }
2165	/// @endcode
2166	///
2167	/// Different lookup criteria can find different names. For example, a
2168	/// particular scope can have both a struct and a function of the same
2169	/// name, and each can be found by certain lookup criteria. For more
2170	/// information about lookup criteria, see the documentation for the
2171	/// class LookupCriteria.
2172	///
2173	/// @param S The scope from which unqualified name lookup will
2174	/// begin. If the lookup criteria permits, name lookup may also search
2175	/// in the parent scopes.
2176	///
2177	/// @param [in,out] R Specifies the lookup to perform (e.g., the name to
2178	/// look up and the lookup kind), and is updated with the results of lookup
2179	/// including zero or more declarations and possibly additional information
2180	/// used to diagnose ambiguities.
2181	///
2182	/// @returns \c true if lookup succeeded and false otherwise.
2183	bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation,
2184	bool ForceNoCPlusPlus) {
2185	DeclarationName Name = R.getLookupName();
2186	if (!Name) return false;
2187
2188	LookupNameKind NameKind = R.getLookupKind();
2189
2190	if (!getLangOpts().CPlusPlus || ForceNoCPlusPlus) {
2191	// Unqualified name lookup in C/Objective-C is purely lexical, so
2192	// search in the declarations attached to the name.
2193	if (NameKind == Sema::LookupRedeclarationWithLinkage) {
2194	// Find the nearest non-transparent declaration scope.
2195	while (!(S->getFlags() & Scope::DeclScope) ||
2196	(S->getEntity() && S->getEntity()->isTransparentContext()))
2197	S = S->getParent();
2198	}
2199
2200	// When performing a scope lookup, we want to find local extern decls.
2201	FindLocalExternScope FindLocals(R);
2202
2203	// Scan up the scope chain looking for a decl that matches this
2204	// identifier that is in the appropriate namespace. This search
2205	// should not take long, as shadowing of names is uncommon, and
2206	// deep shadowing is extremely uncommon.
2207	bool LeftStartingScope = false;
2208
2209	for (IdentifierResolver::iterator I = IdResolver.begin(Name),
2210	IEnd = IdResolver.end();
2211	I != IEnd; ++I)
2212	if (NamedDecl *D = R.getAcceptableDecl(D: *I)) {
2213	if (NameKind == LookupRedeclarationWithLinkage) {
2214	// Determine whether this (or a previous) declaration is
2215	// out-of-scope.
2216	if (!LeftStartingScope && !S->isDeclScope(*I))
2217	LeftStartingScope = true;
2218
2219	// If we found something outside of our starting scope that
2220	// does not have linkage, skip it.
2221	if (LeftStartingScope && !((*I)->hasLinkage())) {
2222	R.setShadowed();
2223	continue;
2224	}
2225	}
2226	else if (NameKind == LookupObjCImplicitSelfParam &&
2227	!isa<ImplicitParamDecl>(Val: *I))
2228	continue;
2229
2230	R.addDecl(D);
2231
2232	// Check whether there are any other declarations with the same name
2233	// and in the same scope.
2234	if (I != IEnd) {
2235	// Find the scope in which this declaration was declared (if it
2236	// actually exists in a Scope).
2237	while (S && !S->isDeclScope(D))
2238	S = S->getParent();
2239
2240	// If the scope containing the declaration is the translation unit,
2241	// then we'll need to perform our checks based on the matching
2242	// DeclContexts rather than matching scopes.
2243	if (S && isNamespaceOrTranslationUnitScope(S))
2244	S = nullptr;
2245
2246	// Compute the DeclContext, if we need it.
2247	DeclContext *DC = nullptr;
2248	if (!S)
2249	DC = (*I)->getDeclContext()->getRedeclContext();
2250
2251	IdentifierResolver::iterator LastI = I;
2252	for (++LastI; LastI != IEnd; ++LastI) {
2253	if (S) {
2254	// Match based on scope.
2255	if (!S->isDeclScope(*LastI))
2256	break;
2257	} else {
2258	// Match based on DeclContext.
2259	DeclContext *LastDC
2260	= (*LastI)->getDeclContext()->getRedeclContext();
2261	if (!LastDC->Equals(DC))
2262	break;
2263	}
2264
2265	// If the declaration is in the right namespace and visible, add it.
2266	if (NamedDecl *LastD = R.getAcceptableDecl(D: *LastI))
2267	R.addDecl(D: LastD);
2268	}
2269
2270	R.resolveKind();
2271	}
2272
2273	return true;
2274	}
2275	} else {
2276	// Perform C++ unqualified name lookup.
2277	if (CppLookupName(R, S))
2278	return true;
2279	}
2280
2281	// If we didn't find a use of this identifier, and if the identifier
2282	// corresponds to a compiler builtin, create the decl object for the builtin
2283	// now, injecting it into translation unit scope, and return it.
2284	if (AllowBuiltinCreation && LookupBuiltin(R))
2285	return true;
2286
2287	// If we didn't find a use of this identifier, the ExternalSource
2288	// may be able to handle the situation.
2289	// Note: some lookup failures are expected!
2290	// See e.g. R.isForRedeclaration().
2291	return (ExternalSource && ExternalSource->LookupUnqualified(R, S));
2292	}
2293
2294	/// Perform qualified name lookup in the namespaces nominated by
2295	/// using directives by the given context.
2296	///
2297	/// C++98 [namespace.qual]p2:
2298	/// Given X::m (where X is a user-declared namespace), or given \::m
2299	/// (where X is the global namespace), let S be the set of all
2300	/// declarations of m in X and in the transitive closure of all
2301	/// namespaces nominated by using-directives in X and its used
2302	/// namespaces, except that using-directives are ignored in any
2303	/// namespace, including X, directly containing one or more
2304	/// declarations of m. No namespace is searched more than once in
2305	/// the lookup of a name. If S is the empty set, the program is
2306	/// ill-formed. Otherwise, if S has exactly one member, or if the
2307	/// context of the reference is a using-declaration
2308	/// (namespace.udecl), S is the required set of declarations of
2309	/// m. Otherwise if the use of m is not one that allows a unique
2310	/// declaration to be chosen from S, the program is ill-formed.
2311	///
2312	/// C++98 [namespace.qual]p5:
2313	/// During the lookup of a qualified namespace member name, if the
2314	/// lookup finds more than one declaration of the member, and if one
2315	/// declaration introduces a class name or enumeration name and the
2316	/// other declarations either introduce the same object, the same
2317	/// enumerator or a set of functions, the non-type name hides the
2318	/// class or enumeration name if and only if the declarations are
2319	/// from the same namespace; otherwise (the declarations are from
2320	/// different namespaces), the program is ill-formed.
2321	static bool LookupQualifiedNameInUsingDirectives(Sema &S, LookupResult &R,
2322	DeclContext *StartDC) {
2323	assert(StartDC->isFileContext() && "start context is not a file context");
2324
2325	// We have not yet looked into these namespaces, much less added
2326	// their "using-children" to the queue.
2327	SmallVector<NamespaceDecl*, 8> Queue;
2328
2329	// We have at least added all these contexts to the queue.
2330	llvm::SmallPtrSet<DeclContext*, 8> Visited;
2331	Visited.insert(Ptr: StartDC);
2332
2333	// We have already looked into the initial namespace; seed the queue
2334	// with its using-children.
2335	for (auto *I : StartDC->using_directives()) {
2336	NamespaceDecl *ND = I->getNominatedNamespace()->getOriginalNamespace();
2337	if (S.isVisible(I) && Visited.insert(ND).second)
2338	Queue.push_back(Elt: ND);
2339	}
2340
2341	// The easiest way to implement the restriction in [namespace.qual]p5
2342	// is to check whether any of the individual results found a tag
2343	// and, if so, to declare an ambiguity if the final result is not
2344	// a tag.
2345	bool FoundTag = false;
2346	bool FoundNonTag = false;
2347
2348	LookupResult LocalR(LookupResult::Temporary, R);
2349
2350	bool Found = false;
2351	while (!Queue.empty()) {
2352	NamespaceDecl *ND = Queue.pop_back_val();
2353
2354	// We go through some convolutions here to avoid copying results
2355	// between LookupResults.
2356	bool UseLocal = !R.empty();
2357	LookupResult &DirectR = UseLocal ? LocalR : R;
2358	bool FoundDirect = LookupDirect(S, DirectR, ND);
2359
2360	if (FoundDirect) {
2361	// First do any local hiding.
2362	DirectR.resolveKind();
2363
2364	// If the local result is a tag, remember that.
2365	if (DirectR.isSingleTagDecl())
2366	FoundTag = true;
2367	else
2368	FoundNonTag = true;
2369
2370	// Append the local results to the total results if necessary.
2371	if (UseLocal) {
2372	R.addAllDecls(Other: LocalR);
2373	LocalR.clear();
2374	}
2375	}
2376
2377	// If we find names in this namespace, ignore its using directives.
2378	if (FoundDirect) {
2379	Found = true;
2380	continue;
2381	}
2382
2383	for (auto *I : ND->using_directives()) {
2384	NamespaceDecl *Nom = I->getNominatedNamespace();
2385	if (S.isVisible(I) && Visited.insert(Nom).second)
2386	Queue.push_back(Nom);
2387	}
2388	}
2389
2390	if (Found) {
2391	if (FoundTag && FoundNonTag)
2392	R.setAmbiguousQualifiedTagHiding();
2393	else
2394	R.resolveKind();
2395	}
2396
2397	return Found;
2398	}
2399
2400	/// Perform qualified name lookup into a given context.
2401	///
2402	/// Qualified name lookup (C++ [basic.lookup.qual]) is used to find
2403	/// names when the context of those names is explicit specified, e.g.,
2404	/// "std::vector" or "x->member", or as part of unqualified name lookup.
2405	///
2406	/// Different lookup criteria can find different names. For example, a
2407	/// particular scope can have both a struct and a function of the same
2408	/// name, and each can be found by certain lookup criteria. For more
2409	/// information about lookup criteria, see the documentation for the
2410	/// class LookupCriteria.
2411	///
2412	/// \param R captures both the lookup criteria and any lookup results found.
2413	///
2414	/// \param LookupCtx The context in which qualified name lookup will
2415	/// search. If the lookup criteria permits, name lookup may also search
2416	/// in the parent contexts or (for C++ classes) base classes.
2417	///
2418	/// \param InUnqualifiedLookup true if this is qualified name lookup that
2419	/// occurs as part of unqualified name lookup.
2420	///
2421	/// \returns true if lookup succeeded, false if it failed.
2422	bool Sema::LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
2423	bool InUnqualifiedLookup) {
2424	assert(LookupCtx && "Sema::LookupQualifiedName requires a lookup context");
2425
2426	if (!R.getLookupName())
2427	return false;
2428
2429	// Make sure that the declaration context is complete.
2430	assert((!isa<TagDecl>(LookupCtx) ||
2431	LookupCtx->isDependentContext() ||
2432	cast<TagDecl>(LookupCtx)->isCompleteDefinition() ||
2433	cast<TagDecl>(LookupCtx)->isBeingDefined()) &&
2434	"Declaration context must already be complete!");
2435
2436	struct QualifiedLookupInScope {
2437	bool oldVal;
2438	DeclContext *Context;
2439	// Set flag in DeclContext informing debugger that we're looking for qualified name
2440	QualifiedLookupInScope(DeclContext *ctx)
2441	: oldVal(ctx->shouldUseQualifiedLookup()), Context(ctx) {
2442	ctx->setUseQualifiedLookup();
2443	}
2444	~QualifiedLookupInScope() {
2445	Context->setUseQualifiedLookup(oldVal);
2446	}
2447	} QL(LookupCtx);
2448
2449	if (LookupDirect(S&: *this, R, DC: LookupCtx)) {
2450	R.resolveKind();
2451	if (isa<CXXRecordDecl>(Val: LookupCtx))
2452	R.setNamingClass(cast<CXXRecordDecl>(Val: LookupCtx));
2453	return true;
2454	}
2455
2456	// Don't descend into implied contexts for redeclarations.
2457	// C++98 [namespace.qual]p6:
2458	// In a declaration for a namespace member in which the
2459	// declarator-id is a qualified-id, given that the qualified-id
2460	// for the namespace member has the form
2461	// nested-name-specifier unqualified-id
2462	// the unqualified-id shall name a member of the namespace
2463	// designated by the nested-name-specifier.
2464	// See also [class.mfct]p5 and [class.static.data]p2.
2465	if (R.isForRedeclaration())
2466	return false;
2467
2468	// If this is a namespace, look it up in the implied namespaces.
2469	if (LookupCtx->isFileContext())
2470	return LookupQualifiedNameInUsingDirectives(S&: *this, R, StartDC: LookupCtx);
2471
2472	// If this isn't a C++ class, we aren't allowed to look into base
2473	// classes, we're done.
2474	CXXRecordDecl *LookupRec = dyn_cast<CXXRecordDecl>(Val: LookupCtx);
2475	if (!LookupRec || !LookupRec->getDefinition())
2476	return false;
2477
2478	// We're done for lookups that can never succeed for C++ classes.
2479	if (R.getLookupKind() == LookupOperatorName ||
2480	R.getLookupKind() == LookupNamespaceName ||
2481	R.getLookupKind() == LookupObjCProtocolName ||
2482	R.getLookupKind() == LookupLabel)
2483	return false;
2484
2485	// If we're performing qualified name lookup into a dependent class,
2486	// then we are actually looking into a current instantiation. If we have any
2487	// dependent base classes, then we either have to delay lookup until
2488	// template instantiation time (at which point all bases will be available)
2489	// or we have to fail.
2490	if (!InUnqualifiedLookup && LookupRec->isDependentContext() &&
2491	LookupRec->hasAnyDependentBases()) {
2492	R.setNotFoundInCurrentInstantiation();
2493	return false;
2494	}
2495
2496	// Perform lookup into our base classes.
2497
2498	DeclarationName Name = R.getLookupName();
2499	unsigned IDNS = R.getIdentifierNamespace();
2500
2501	// Look for this member in our base classes.
2502	auto BaseCallback = [Name, IDNS](const CXXBaseSpecifier *Specifier,
2503	CXXBasePath &Path) -> bool {
2504	CXXRecordDecl *BaseRecord = Specifier->getType()->getAsCXXRecordDecl();
2505	// Drop leading non-matching lookup results from the declaration list so
2506	// we don't need to consider them again below.
2507	for (Path.Decls = BaseRecord->lookup(Name).begin();
2508	Path.Decls != Path.Decls.end(); ++Path.Decls) {
2509	if ((*Path.Decls)->isInIdentifierNamespace(IDNS))
2510	return true;
2511	}
2512	return false;
2513	};
2514
2515	CXXBasePaths Paths;
2516	Paths.setOrigin(LookupRec);
2517	if (!LookupRec->lookupInBases(BaseMatches: BaseCallback, Paths))
2518	return false;
2519
2520	R.setNamingClass(LookupRec);
2521
2522	// C++ [class.member.lookup]p2:
2523	// [...] If the resulting set of declarations are not all from
2524	// sub-objects of the same type, or the set has a nonstatic member
2525	// and includes members from distinct sub-objects, there is an
2526	// ambiguity and the program is ill-formed. Otherwise that set is
2527	// the result of the lookup.
2528	QualType SubobjectType;
2529	int SubobjectNumber = 0;
2530	AccessSpecifier SubobjectAccess = AS_none;
2531
2532	// Check whether the given lookup result contains only static members.
2533	auto HasOnlyStaticMembers = [&](DeclContext::lookup_iterator Result) {
2534	for (DeclContext::lookup_iterator I = Result, E = I.end(); I != E; ++I)
2535	if ((*I)->isInIdentifierNamespace(IDNS) && (*I)->isCXXInstanceMember())
2536	return false;
2537	return true;
2538	};
2539
2540	bool TemplateNameLookup = R.isTemplateNameLookup();
2541
2542	// Determine whether two sets of members contain the same members, as
2543	// required by C++ [class.member.lookup]p6.
2544	auto HasSameDeclarations = [&](DeclContext::lookup_iterator A,
2545	DeclContext::lookup_iterator B) {
2546	using Iterator = DeclContextLookupResult::iterator;
2547	using Result = const void *;
2548
2549	auto Next = [&](Iterator &It, Iterator End) -> Result {
2550	while (It != End) {
2551	NamedDecl *ND = *It++;
2552	if (!ND->isInIdentifierNamespace(IDNS))
2553	continue;
2554
2555	// C++ [temp.local]p3:
2556	// A lookup that finds an injected-class-name (10.2) can result in
2557	// an ambiguity in certain cases (for example, if it is found in
2558	// more than one base class). If all of the injected-class-names
2559	// that are found refer to specializations of the same class
2560	// template, and if the name is used as a template-name, the
2561	// reference refers to the class template itself and not a
2562	// specialization thereof, and is not ambiguous.
2563	if (TemplateNameLookup)
2564	if (auto *TD = getAsTemplateNameDecl(D: ND))
2565	ND = TD;
2566
2567	// C++ [class.member.lookup]p3:
2568	// type declarations (including injected-class-names) are replaced by
2569	// the types they designate
2570	if (const TypeDecl *TD = dyn_cast<TypeDecl>(Val: ND->getUnderlyingDecl())) {
2571	QualType T = Context.getTypeDeclType(Decl: TD);
2572	return T.getCanonicalType().getAsOpaquePtr();
2573	}
2574
2575	return ND->getUnderlyingDecl()->getCanonicalDecl();
2576	}
2577	return nullptr;
2578	};
2579
2580	// We'll often find the declarations are in the same order. Handle this
2581	// case (and the special case of only one declaration) efficiently.
2582	Iterator AIt = A, BIt = B, AEnd, BEnd;
2583	while (true) {
2584	Result AResult = Next(AIt, AEnd);
2585	Result BResult = Next(BIt, BEnd);
2586	if (!AResult && !BResult)
2587	return true;
2588	if (!AResult || !BResult)
2589	return false;
2590	if (AResult != BResult) {
2591	// Found a mismatch; carefully check both lists, accounting for the
2592	// possibility of declarations appearing more than once.
2593	llvm::SmallDenseMap<Result, bool, 32> AResults;
2594	for (; AResult; AResult = Next(AIt, AEnd))
2595	AResults.insert(KV: {AResult, /*FoundInB*/false});
2596	unsigned Found = 0;
2597	for (; BResult; BResult = Next(BIt, BEnd)) {
2598	auto It = AResults.find(Val: BResult);
2599	if (It == AResults.end())
2600	return false;
2601	if (!It->second) {
2602	It->second = true;
2603	++Found;
2604	}
2605	}
2606	return AResults.size() == Found;
2607	}
2608	}
2609	};
2610
2611	for (CXXBasePaths::paths_iterator Path = Paths.begin(), PathEnd = Paths.end();
2612	Path != PathEnd; ++Path) {
2613	const CXXBasePathElement &PathElement = Path->back();
2614
2615	// Pick the best (i.e. most permissive i.e. numerically lowest) access
2616	// across all paths.
2617	SubobjectAccess = std::min(a: SubobjectAccess, b: Path->Access);
2618
2619	// Determine whether we're looking at a distinct sub-object or not.
2620	if (SubobjectType.isNull()) {
2621	// This is the first subobject we've looked at. Record its type.
2622	SubobjectType = Context.getCanonicalType(T: PathElement.Base->getType());
2623	SubobjectNumber = PathElement.SubobjectNumber;
2624	continue;
2625	}
2626
2627	if (SubobjectType !=
2628	Context.getCanonicalType(T: PathElement.Base->getType())) {
2629	// We found members of the given name in two subobjects of
2630	// different types. If the declaration sets aren't the same, this
2631	// lookup is ambiguous.
2632	//
2633	// FIXME: The language rule says that this applies irrespective of
2634	// whether the sets contain only static members.
2635	if (HasOnlyStaticMembers(Path->Decls) &&
2636	HasSameDeclarations(Paths.begin()->Decls, Path->Decls))
2637	continue;
2638
2639	R.setAmbiguousBaseSubobjectTypes(Paths);
2640	return true;
2641	}
2642
2643	// FIXME: This language rule no longer exists. Checking for ambiguous base
2644	// subobjects should be done as part of formation of a class member access
2645	// expression (when converting the object parameter to the member's type).
2646	if (SubobjectNumber != PathElement.SubobjectNumber) {
2647	// We have a different subobject of the same type.
2648
2649	// C++ [class.member.lookup]p5:
2650	// A static member, a nested type or an enumerator defined in
2651	// a base class T can unambiguously be found even if an object
2652	// has more than one base class subobject of type T.
2653	if (HasOnlyStaticMembers(Path->Decls))
2654	continue;
2655
2656	// We have found a nonstatic member name in multiple, distinct
2657	// subobjects. Name lookup is ambiguous.
2658	R.setAmbiguousBaseSubobjects(Paths);
2659	return true;
2660	}
2661	}
2662
2663	// Lookup in a base class succeeded; return these results.
2664
2665	for (DeclContext::lookup_iterator I = Paths.front().Decls, E = I.end();
2666	I != E; ++I) {
2667	AccessSpecifier AS = CXXRecordDecl::MergeAccess(PathAccess: SubobjectAccess,
2668	DeclAccess: (*I)->getAccess());
2669	if (NamedDecl *ND = R.getAcceptableDecl(D: *I))
2670	R.addDecl(D: ND, AS);
2671	}
2672	R.resolveKind();
2673	return true;
2674	}
2675
2676	/// Performs qualified name lookup or special type of lookup for
2677	/// "__super::" scope specifier.
2678	///
2679	/// This routine is a convenience overload meant to be called from contexts
2680	/// that need to perform a qualified name lookup with an optional C++ scope
2681	/// specifier that might require special kind of lookup.
2682	///
2683	/// \param R captures both the lookup criteria and any lookup results found.
2684	///
2685	/// \param LookupCtx The context in which qualified name lookup will
2686	/// search.
2687	///
2688	/// \param SS An optional C++ scope-specifier.
2689	///
2690	/// \returns true if lookup succeeded, false if it failed.
2691	bool Sema::LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
2692	CXXScopeSpec &SS) {
2693	auto *NNS = SS.getScopeRep();
2694	if (NNS && NNS->getKind() == NestedNameSpecifier::Super)
2695	return LookupInSuper(R, Class: NNS->getAsRecordDecl());
2696	else
2697
2698	return LookupQualifiedName(R, LookupCtx);
2699	}
2700
2701	/// Performs name lookup for a name that was parsed in the
2702	/// source code, and may contain a C++ scope specifier.
2703	///
2704	/// This routine is a convenience routine meant to be called from
2705	/// contexts that receive a name and an optional C++ scope specifier
2706	/// (e.g., "N::M::x"). It will then perform either qualified or
2707	/// unqualified name lookup (with LookupQualifiedName or LookupName,
2708	/// respectively) on the given name and return those results. It will
2709	/// perform a special type of lookup for "__super::" scope specifier.
2710	///
2711	/// @param S The scope from which unqualified name lookup will
2712	/// begin.
2713	///
2714	/// @param SS An optional C++ scope-specifier, e.g., "::N::M".
2715	///
2716	/// @param EnteringContext Indicates whether we are going to enter the
2717	/// context of the scope-specifier SS (if present).
2718	///
2719	/// @returns True if any decls were found (but possibly ambiguous)
2720	bool Sema::LookupParsedName(LookupResult &R, Scope *S, CXXScopeSpec *SS,
2721	bool AllowBuiltinCreation, bool EnteringContext) {
2722	if (SS && SS->isInvalid()) {
2723	// When the scope specifier is invalid, don't even look for
2724	// anything.
2725	return false;
2726	}
2727
2728	if (SS && SS->isSet()) {
2729	NestedNameSpecifier *NNS = SS->getScopeRep();
2730	if (NNS->getKind() == NestedNameSpecifier::Super)
2731	return LookupInSuper(R, Class: NNS->getAsRecordDecl());
2732
2733	if (DeclContext *DC = computeDeclContext(SS: *SS, EnteringContext)) {
2734	// We have resolved the scope specifier to a particular declaration
2735	// contex, and will perform name lookup in that context.
2736	if (!DC->isDependentContext() && RequireCompleteDeclContext(SS&: *SS, DC))
2737	return false;
2738
2739	R.setContextRange(SS->getRange());
2740	return LookupQualifiedName(R, LookupCtx: DC);
2741	}
2742
2743	// We could not resolve the scope specified to a specific declaration
2744	// context, which means that SS refers to an unknown specialization.
2745	// Name lookup can't find anything in this case.
2746	R.setNotFoundInCurrentInstantiation();
2747	R.setContextRange(SS->getRange());
2748	return false;
2749	}
2750
2751	// Perform unqualified name lookup starting in the given scope.
2752	return LookupName(R, S, AllowBuiltinCreation);
2753	}
2754
2755	/// Perform qualified name lookup into all base classes of the given
2756	/// class.
2757	///
2758	/// \param R captures both the lookup criteria and any lookup results found.
2759	///
2760	/// \param Class The context in which qualified name lookup will
2761	/// search. Name lookup will search in all base classes merging the results.
2762	///
2763	/// @returns True if any decls were found (but possibly ambiguous)
2764	bool Sema::LookupInSuper(LookupResult &R, CXXRecordDecl *Class) {
2765	// The access-control rules we use here are essentially the rules for
2766	// doing a lookup in Class that just magically skipped the direct
2767	// members of Class itself. That is, the naming class is Class, and the
2768	// access includes the access of the base.
2769	for (const auto &BaseSpec : Class->bases()) {
2770	CXXRecordDecl *RD = cast<CXXRecordDecl>(
2771	Val: BaseSpec.getType()->castAs<RecordType>()->getDecl());
2772	LookupResult Result(*this, R.getLookupNameInfo(), R.getLookupKind());
2773	Result.setBaseObjectType(Context.getRecordType(Class));
2774	LookupQualifiedName(Result, RD);
2775
2776	// Copy the lookup results into the target, merging the base's access into
2777	// the path access.
2778	for (auto I = Result.begin(), E = Result.end(); I != E; ++I) {
2779	R.addDecl(D: I.getDecl(),
2780	AS: CXXRecordDecl::MergeAccess(PathAccess: BaseSpec.getAccessSpecifier(),
2781	DeclAccess: I.getAccess()));
2782	}
2783
2784	Result.suppressDiagnostics();
2785	}
2786
2787	R.resolveKind();
2788	R.setNamingClass(Class);
2789
2790	return !R.empty();
2791	}
2792
2793	/// Produce a diagnostic describing the ambiguity that resulted
2794	/// from name lookup.
2795	///
2796	/// \param Result The result of the ambiguous lookup to be diagnosed.
2797	void Sema::DiagnoseAmbiguousLookup(LookupResult &Result) {
2798	assert(Result.isAmbiguous() && "Lookup result must be ambiguous");
2799
2800	DeclarationName Name = Result.getLookupName();
2801	SourceLocation NameLoc = Result.getNameLoc();
2802	SourceRange LookupRange = Result.getContextRange();
2803
2804	switch (Result.getAmbiguityKind()) {
2805	case LookupResult::AmbiguousBaseSubobjects: {
2806	CXXBasePaths *Paths = Result.getBasePaths();
2807	QualType SubobjectType = Paths->front().back().Base->getType();
2808	Diag(NameLoc, diag::err_ambiguous_member_multiple_subobjects)
2809	<< Name << SubobjectType << getAmbiguousPathsDisplayString(*Paths)
2810	<< LookupRange;
2811
2812	DeclContext::lookup_iterator Found = Paths->front().Decls;
2813	while (isa<CXXMethodDecl>(Val: *Found) &&
2814	cast<CXXMethodDecl>(Val: *Found)->isStatic())
2815	++Found;
2816
2817	Diag((*Found)->getLocation(), diag::note_ambiguous_member_found);
2818	break;
2819	}
2820
2821	case LookupResult::AmbiguousBaseSubobjectTypes: {
2822	Diag(NameLoc, diag::err_ambiguous_member_multiple_subobject_types)
2823	<< Name << LookupRange;
2824
2825	CXXBasePaths *Paths = Result.getBasePaths();
2826	std::set<const NamedDecl *> DeclsPrinted;
2827	for (CXXBasePaths::paths_iterator Path = Paths->begin(),
2828	PathEnd = Paths->end();
2829	Path != PathEnd; ++Path) {
2830	const NamedDecl *D = *Path->Decls;
2831	if (!D->isInIdentifierNamespace(Result.getIdentifierNamespace()))
2832	continue;
2833	if (DeclsPrinted.insert(x: D).second) {
2834	if (const auto *TD = dyn_cast<TypedefNameDecl>(D->getUnderlyingDecl()))
2835	Diag(D->getLocation(), diag::note_ambiguous_member_type_found)
2836	<< TD->getUnderlyingType();
2837	else if (const auto *TD = dyn_cast<TypeDecl>(D->getUnderlyingDecl()))
2838	Diag(D->getLocation(), diag::note_ambiguous_member_type_found)
2839	<< Context.getTypeDeclType(TD);
2840	else
2841	Diag(D->getLocation(), diag::note_ambiguous_member_found);
2842	}
2843	}
2844	break;
2845	}
2846
2847	case LookupResult::AmbiguousTagHiding: {
2848	Diag(NameLoc, diag::err_ambiguous_tag_hiding) << Name << LookupRange;
2849
2850	llvm::SmallPtrSet<NamedDecl*, 8> TagDecls;
2851
2852	for (auto *D : Result)
2853	if (TagDecl *TD = dyn_cast<TagDecl>(Val: D)) {
2854	TagDecls.insert(TD);
2855	Diag(TD->getLocation(), diag::note_hidden_tag);
2856	}
2857
2858	for (auto *D : Result)
2859	if (!isa<TagDecl>(D))
2860	Diag(D->getLocation(), diag::note_hiding_object);
2861
2862	// For recovery purposes, go ahead and implement the hiding.
2863	LookupResult::Filter F = Result.makeFilter();
2864	while (F.hasNext()) {
2865	if (TagDecls.count(Ptr: F.next()))
2866	F.erase();
2867	}
2868	F.done();
2869	break;
2870	}
2871
2872	case LookupResult::AmbiguousReferenceToPlaceholderVariable: {
2873	Diag(NameLoc, diag::err_using_placeholder_variable) << Name << LookupRange;
2874	DeclContext *DC = nullptr;
2875	for (auto *D : Result) {
2876	Diag(D->getLocation(), diag::note_reference_placeholder) << D;
2877	if (DC != nullptr && DC != D->getDeclContext())
2878	break;
2879	DC = D->getDeclContext();
2880	}
2881	break;
2882	}
2883
2884	case LookupResult::AmbiguousReference: {
2885	Diag(NameLoc, diag::err_ambiguous_reference) << Name << LookupRange;
2886
2887	for (auto *D : Result)
2888	Diag(D->getLocation(), diag::note_ambiguous_candidate) << D;
2889	break;
2890	}
2891	}
2892	}
2893
2894	namespace {
2895	struct AssociatedLookup {
2896	AssociatedLookup(Sema &S, SourceLocation InstantiationLoc,
2897	Sema::AssociatedNamespaceSet &Namespaces,
2898	Sema::AssociatedClassSet &Classes)
2899	: S(S), Namespaces(Namespaces), Classes(Classes),
2900	InstantiationLoc(InstantiationLoc) {
2901	}
2902
2903	bool addClassTransitive(CXXRecordDecl *RD) {
2904	Classes.insert(X: RD);
2905	return ClassesTransitive.insert(X: RD);
2906	}
2907
2908	Sema &S;
2909	Sema::AssociatedNamespaceSet &Namespaces;
2910	Sema::AssociatedClassSet &Classes;
2911	SourceLocation InstantiationLoc;
2912
2913	private:
2914	Sema::AssociatedClassSet ClassesTransitive;
2915	};
2916	} // end anonymous namespace
2917
2918	static void
2919	addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType T);
2920
2921	// Given the declaration context \param Ctx of a class, class template or
2922	// enumeration, add the associated namespaces to \param Namespaces as described
2923	// in [basic.lookup.argdep]p2.
2924	static void CollectEnclosingNamespace(Sema::AssociatedNamespaceSet &Namespaces,
2925	DeclContext *Ctx) {
2926	// The exact wording has been changed in C++14 as a result of
2927	// CWG 1691 (see also CWG 1690 and CWG 1692). We apply it unconditionally
2928	// to all language versions since it is possible to return a local type
2929	// from a lambda in C++11.
2930	//
2931	// C++14 [basic.lookup.argdep]p2:
2932	// If T is a class type [...]. Its associated namespaces are the innermost
2933	// enclosing namespaces of its associated classes. [...]
2934	//
2935	// If T is an enumeration type, its associated namespace is the innermost
2936	// enclosing namespace of its declaration. [...]
2937
2938	// We additionally skip inline namespaces. The innermost non-inline namespace
2939	// contains all names of all its nested inline namespaces anyway, so we can
2940	// replace the entire inline namespace tree with its root.
2941	while (!Ctx->isFileContext() || Ctx->isInlineNamespace())
2942	Ctx = Ctx->getParent();
2943
2944	Namespaces.insert(X: Ctx->getPrimaryContext());
2945	}
2946
2947	// Add the associated classes and namespaces for argument-dependent
2948	// lookup that involves a template argument (C++ [basic.lookup.argdep]p2).
2949	static void
2950	addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
2951	const TemplateArgument &Arg) {
2952	// C++ [basic.lookup.argdep]p2, last bullet:
2953	// -- [...] ;
2954	switch (Arg.getKind()) {
2955	case TemplateArgument::Null:
2956	break;
2957
2958	case TemplateArgument::Type:
2959	// [...] the namespaces and classes associated with the types of the
2960	// template arguments provided for template type parameters (excluding
2961	// template template parameters)
2962	addAssociatedClassesAndNamespaces(Result, T: Arg.getAsType());
2963	break;
2964
2965	case TemplateArgument::Template:
2966	case TemplateArgument::TemplateExpansion: {
2967	// [...] the namespaces in which any template template arguments are
2968	// defined; and the classes in which any member templates used as
2969	// template template arguments are defined.
2970	TemplateName Template = Arg.getAsTemplateOrTemplatePattern();
2971	if (ClassTemplateDecl *ClassTemplate
2972	= dyn_cast<ClassTemplateDecl>(Val: Template.getAsTemplateDecl())) {
2973	DeclContext *Ctx = ClassTemplate->getDeclContext();
2974	if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Val: Ctx))
2975	Result.Classes.insert(X: EnclosingClass);
2976	// Add the associated namespace for this class.
2977	CollectEnclosingNamespace(Namespaces&: Result.Namespaces, Ctx);
2978	}
2979	break;
2980	}
2981
2982	case TemplateArgument::Declaration:
2983	case TemplateArgument::Integral:
2984	case TemplateArgument::Expression:
2985	case TemplateArgument::NullPtr:
2986	case TemplateArgument::StructuralValue:
2987	// [Note: non-type template arguments do not contribute to the set of
2988	// associated namespaces. ]
2989	break;
2990
2991	case TemplateArgument::Pack:
2992	for (const auto &P : Arg.pack_elements())
2993	addAssociatedClassesAndNamespaces(Result, Arg: P);
2994	break;
2995	}
2996	}
2997
2998	// Add the associated classes and namespaces for argument-dependent lookup
2999	// with an argument of class type (C++ [basic.lookup.argdep]p2).
3000	static void
3001	addAssociatedClassesAndNamespaces(AssociatedLookup &Result,
3002	CXXRecordDecl *Class) {
3003
3004	// Just silently ignore anything whose name is __va_list_tag.
3005	if (Class->getDeclName() == Result.S.VAListTagName)
3006	return;
3007
3008	// C++ [basic.lookup.argdep]p2:
3009	// [...]
3010	// -- If T is a class type (including unions), its associated
3011	// classes are: the class itself; the class of which it is a
3012	// member, if any; and its direct and indirect base classes.
3013	// Its associated namespaces are the innermost enclosing
3014	// namespaces of its associated classes.
3015
3016	// Add the class of which it is a member, if any.
3017	DeclContext *Ctx = Class->getDeclContext();
3018	if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Val: Ctx))
3019	Result.Classes.insert(X: EnclosingClass);
3020
3021	// Add the associated namespace for this class.
3022	CollectEnclosingNamespace(Namespaces&: Result.Namespaces, Ctx);
3023
3024	// -- If T is a template-id, its associated namespaces and classes are
3025	// the namespace in which the template is defined; for member
3026	// templates, the member template's class; the namespaces and classes
3027	// associated with the types of the template arguments provided for
3028	// template type parameters (excluding template template parameters); the
3029	// namespaces in which any template template arguments are defined; and
3030	// the classes in which any member templates used as template template
3031	// arguments are defined. [Note: non-type template arguments do not
3032	// contribute to the set of associated namespaces. ]
3033	if (ClassTemplateSpecializationDecl *Spec
3034	= dyn_cast<ClassTemplateSpecializationDecl>(Val: Class)) {
3035	DeclContext *Ctx = Spec->getSpecializedTemplate()->getDeclContext();
3036	if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Val: Ctx))
3037	Result.Classes.insert(X: EnclosingClass);
3038	// Add the associated namespace for this class.
3039	CollectEnclosingNamespace(Namespaces&: Result.Namespaces, Ctx);
3040
3041	const TemplateArgumentList &TemplateArgs = Spec->getTemplateArgs();
3042	for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
3043	addAssociatedClassesAndNamespaces(Result, Arg: TemplateArgs[I]);
3044	}
3045
3046	// Add the class itself. If we've already transitively visited this class,
3047	// we don't need to visit base classes.
3048	if (!Result.addClassTransitive(RD: Class))
3049	return;
3050
3051	// Only recurse into base classes for complete types.
3052	if (!Result.S.isCompleteType(Loc: Result.InstantiationLoc,
3053	T: Result.S.Context.getRecordType(Class)))
3054	return;
3055
3056	// Add direct and indirect base classes along with their associated
3057	// namespaces.
3058	SmallVector<CXXRecordDecl *, 32> Bases;
3059	Bases.push_back(Elt: Class);
3060	while (!Bases.empty()) {
3061	// Pop this class off the stack.
3062	Class = Bases.pop_back_val();
3063
3064	// Visit the base classes.
3065	for (const auto &Base : Class->bases()) {
3066	const RecordType *BaseType = Base.getType()->getAs<RecordType>();
3067	// In dependent contexts, we do ADL twice, and the first time around,
3068	// the base type might be a dependent TemplateSpecializationType, or a
3069	// TemplateTypeParmType. If that happens, simply ignore it.
3070	// FIXME: If we want to support export, we probably need to add the
3071	// namespace of the template in a TemplateSpecializationType, or even
3072	// the classes and namespaces of known non-dependent arguments.
3073	if (!BaseType)
3074	continue;
3075	CXXRecordDecl *BaseDecl = cast<CXXRecordDecl>(Val: BaseType->getDecl());
3076	if (Result.addClassTransitive(RD: BaseDecl)) {
3077	// Find the associated namespace for this base class.
3078	DeclContext *BaseCtx = BaseDecl->getDeclContext();
3079	CollectEnclosingNamespace(Namespaces&: Result.Namespaces, Ctx: BaseCtx);
3080
3081	// Make sure we visit the bases of this base class.
3082	if (BaseDecl->bases_begin() != BaseDecl->bases_end())
3083	Bases.push_back(Elt: BaseDecl);
3084	}
3085	}
3086	}
3087	}
3088
3089	// Add the associated classes and namespaces for
3090	// argument-dependent lookup with an argument of type T
3091	// (C++ [basic.lookup.koenig]p2).
3092	static void
3093	addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType Ty) {
3094	// C++ [basic.lookup.koenig]p2:
3095	//
3096	// For each argument type T in the function call, there is a set
3097	// of zero or more associated namespaces and a set of zero or more
3098	// associated classes to be considered. The sets of namespaces and
3099	// classes is determined entirely by the types of the function
3100	// arguments (and the namespace of any template template
3101	// argument). Typedef names and using-declarations used to specify
3102	// the types do not contribute to this set. The sets of namespaces
3103	// and classes are determined in the following way:
3104
3105	SmallVector<const Type *, 16> Queue;
3106	const Type *T = Ty->getCanonicalTypeInternal().getTypePtr();
3107
3108	while (true) {
3109	switch (T->getTypeClass()) {
3110
3111	#define TYPE(Class, Base)
3112	#define DEPENDENT_TYPE(Class, Base) case Type::Class:
3113	#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
3114	#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
3115	#define ABSTRACT_TYPE(Class, Base)
3116	#include "clang/AST/TypeNodes.inc"
3117	// T is canonical. We can also ignore dependent types because
3118	// we don't need to do ADL at the definition point, but if we
3119	// wanted to implement template export (or if we find some other
3120	// use for associated classes and namespaces...) this would be
3121	// wrong.
3122	break;
3123
3124	// -- If T is a pointer to U or an array of U, its associated
3125	// namespaces and classes are those associated with U.
3126	case Type::Pointer:
3127	T = cast<PointerType>(T)->getPointeeType().getTypePtr();
3128	continue;
3129	case Type::ConstantArray:
3130	case Type::IncompleteArray:
3131	case Type::VariableArray:
3132	T = cast<ArrayType>(T)->getElementType().getTypePtr();
3133	continue;
3134
3135	// -- If T is a fundamental type, its associated sets of
3136	// namespaces and classes are both empty.
3137	case Type::Builtin:
3138	break;
3139
3140	// -- If T is a class type (including unions), its associated
3141	// classes are: the class itself; the class of which it is
3142	// a member, if any; and its direct and indirect base classes.
3143	// Its associated namespaces are the innermost enclosing
3144	// namespaces of its associated classes.
3145	case Type::Record: {
3146	CXXRecordDecl *Class =
3147	cast<CXXRecordDecl>(cast<RecordType>(T)->getDecl());
3148	addAssociatedClassesAndNamespaces(Result, Class);
3149	break;
3150	}
3151
3152	// -- If T is an enumeration type, its associated namespace
3153	// is the innermost enclosing namespace of its declaration.
3154	// If it is a class member, its associated class is the
3155	// member’s class; else it has no associated class.
3156	case Type::Enum: {
3157	EnumDecl *Enum = cast<EnumType>(T)->getDecl();
3158
3159	DeclContext *Ctx = Enum->getDeclContext();
3160	if (CXXRecordDecl *EnclosingClass = dyn_cast<CXXRecordDecl>(Ctx))
3161	Result.Classes.insert(X: EnclosingClass);
3162
3163	// Add the associated namespace for this enumeration.
3164	CollectEnclosingNamespace(Namespaces&: Result.Namespaces, Ctx);
3165
3166	break;
3167	}
3168
3169	// -- If T is a function type, its associated namespaces and
3170	// classes are those associated with the function parameter
3171	// types and those associated with the return type.
3172	case Type::FunctionProto: {
3173	const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
3174	for (const auto &Arg : Proto->param_types())
3175	Queue.push_back(Arg.getTypePtr());
3176	// fallthrough
3177	[[fallthrough]];
3178	}
3179	case Type::FunctionNoProto: {
3180	const FunctionType *FnType = cast<FunctionType>(T);
3181	T = FnType->getReturnType().getTypePtr();
3182	continue;
3183	}
3184
3185	// -- If T is a pointer to a member function of a class X, its
3186	// associated namespaces and classes are those associated
3187	// with the function parameter types and return type,
3188	// together with those associated with X.
3189	//
3190	// -- If T is a pointer to a data member of class X, its
3191	// associated namespaces and classes are those associated
3192	// with the member type together with those associated with
3193	// X.
3194	case Type::MemberPointer: {
3195	const MemberPointerType *MemberPtr = cast<MemberPointerType>(T);
3196
3197	// Queue up the class type into which this points.
3198	Queue.push_back(Elt: MemberPtr->getClass());
3199
3200	// And directly continue with the pointee type.
3201	T = MemberPtr->getPointeeType().getTypePtr();
3202	continue;
3203	}
3204
3205	// As an extension, treat this like a normal pointer.
3206	case Type::BlockPointer:
3207	T = cast<BlockPointerType>(T)->getPointeeType().getTypePtr();
3208	continue;
3209
3210	// References aren't covered by the standard, but that's such an
3211	// obvious defect that we cover them anyway.
3212	case Type::LValueReference:
3213	case Type::RValueReference:
3214	T = cast<ReferenceType>(T)->getPointeeType().getTypePtr();
3215	continue;
3216
3217	// These are fundamental types.
3218	case Type::Vector:
3219	case Type::ExtVector:
3220	case Type::ConstantMatrix:
3221	case Type::Complex:
3222	case Type::BitInt:
3223	break;
3224
3225	// Non-deduced auto types only get here for error cases.
3226	case Type::Auto:
3227	case Type::DeducedTemplateSpecialization:
3228	break;
3229
3230	// If T is an Objective-C object or interface type, or a pointer to an
3231	// object or interface type, the associated namespace is the global
3232	// namespace.
3233	case Type::ObjCObject:
3234	case Type::ObjCInterface:
3235	case Type::ObjCObjectPointer:
3236	Result.Namespaces.insert(Result.S.Context.getTranslationUnitDecl());
3237	break;
3238
3239	// Atomic types are just wrappers; use the associations of the
3240	// contained type.
3241	case Type::Atomic:
3242	T = cast<AtomicType>(T)->getValueType().getTypePtr();
3243	continue;
3244	case Type::Pipe:
3245	T = cast<PipeType>(T)->getElementType().getTypePtr();
3246	continue;
3247
3248	// Array parameter types are treated as fundamental types.
3249	case Type::ArrayParameter:
3250	break;
3251	}
3252
3253	if (Queue.empty())
3254	break;
3255	T = Queue.pop_back_val();
3256	}
3257	}
3258
3259	/// Find the associated classes and namespaces for
3260	/// argument-dependent lookup for a call with the given set of
3261	/// arguments.
3262	///
3263	/// This routine computes the sets of associated classes and associated
3264	/// namespaces searched by argument-dependent lookup
3265	/// (C++ [basic.lookup.argdep]) for a given set of arguments.
3266	void Sema::FindAssociatedClassesAndNamespaces(
3267	SourceLocation InstantiationLoc, ArrayRef<Expr *> Args,
3268	AssociatedNamespaceSet &AssociatedNamespaces,
3269	AssociatedClassSet &AssociatedClasses) {
3270	AssociatedNamespaces.clear();
3271	AssociatedClasses.clear();
3272
3273	AssociatedLookup Result(*this, InstantiationLoc,
3274	AssociatedNamespaces, AssociatedClasses);
3275
3276	// C++ [basic.lookup.koenig]p2:
3277	// For each argument type T in the function call, there is a set
3278	// of zero or more associated namespaces and a set of zero or more
3279	// associated classes to be considered. The sets of namespaces and
3280	// classes is determined entirely by the types of the function
3281	// arguments (and the namespace of any template template
3282	// argument).
3283	for (unsigned ArgIdx = 0; ArgIdx != Args.size(); ++ArgIdx) {
3284	Expr *Arg = Args[ArgIdx];
3285
3286	if (Arg->getType() != Context.OverloadTy) {
3287	addAssociatedClassesAndNamespaces(Result, Ty: Arg->getType());
3288	continue;
3289	}
3290
3291	// [...] In addition, if the argument is the name or address of a
3292	// set of overloaded functions and/or function templates, its
3293	// associated classes and namespaces are the union of those
3294	// associated with each of the members of the set: the namespace
3295	// in which the function or function template is defined and the
3296	// classes and namespaces associated with its (non-dependent)
3297	// parameter types and return type.
3298	OverloadExpr *OE = OverloadExpr::find(E: Arg).Expression;
3299
3300	for (const NamedDecl *D : OE->decls()) {
3301	// Look through any using declarations to find the underlying function.
3302	const FunctionDecl *FDecl = D->getUnderlyingDecl()->getAsFunction();
3303
3304	// Add the classes and namespaces associated with the parameter
3305	// types and return type of this function.
3306	addAssociatedClassesAndNamespaces(Result, FDecl->getType());
3307	}
3308	}
3309	}
3310
3311	NamedDecl *Sema::LookupSingleName(Scope *S, DeclarationName Name,
3312	SourceLocation Loc,
3313	LookupNameKind NameKind,
3314	RedeclarationKind Redecl) {
3315	LookupResult R(*this, Name, Loc, NameKind, Redecl);
3316	LookupName(R, S);
3317	return R.getAsSingle<NamedDecl>();
3318	}
3319
3320	/// Find the protocol with the given name, if any.
3321	ObjCProtocolDecl *Sema::LookupProtocol(IdentifierInfo *II,
3322	SourceLocation IdLoc,
3323	RedeclarationKind Redecl) {
3324	Decl *D = LookupSingleName(S: TUScope, Name: II, Loc: IdLoc,
3325	NameKind: LookupObjCProtocolName, Redecl);
3326	return cast_or_null<ObjCProtocolDecl>(Val: D);
3327	}
3328
3329	void Sema::LookupOverloadedOperatorName(OverloadedOperatorKind Op, Scope *S,
3330	UnresolvedSetImpl &Functions) {
3331	// C++ [over.match.oper]p3:
3332	// -- The set of non-member candidates is the result of the
3333	// unqualified lookup of operator@ in the context of the
3334	// expression according to the usual rules for name lookup in
3335	// unqualified function calls (3.4.2) except that all member
3336	// functions are ignored.
3337	DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(Op);
3338	LookupResult Operators(*this, OpName, SourceLocation(), LookupOperatorName);
3339	LookupName(R&: Operators, S);
3340
3341	assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
3342	Functions.append(I: Operators.begin(), E: Operators.end());
3343	}
3344
3345	Sema::SpecialMemberOverloadResult
3346	Sema::LookupSpecialMember(CXXRecordDecl *RD, CXXSpecialMemberKind SM,
3347	bool ConstArg, bool VolatileArg, bool RValueThis,
3348	bool ConstThis, bool VolatileThis) {
3349	assert(CanDeclareSpecialMemberFunction(RD) &&
3350	"doing special member lookup into record that isn't fully complete");
3351	RD = RD->getDefinition();
3352	if (RValueThis || ConstThis || VolatileThis)
3353	assert((SM == CXXSpecialMemberKind::CopyAssignment ||
3354	SM == CXXSpecialMemberKind::MoveAssignment) &&
3355	"constructors and destructors always have unqualified lvalue this");
3356	if (ConstArg || VolatileArg)
3357	assert((SM != CXXSpecialMemberKind::DefaultConstructor &&
3358	SM != CXXSpecialMemberKind::Destructor) &&
3359	"parameter-less special members can't have qualified arguments");
3360
3361	// FIXME: Get the caller to pass in a location for the lookup.
3362	SourceLocation LookupLoc = RD->getLocation();
3363
3364	llvm::FoldingSetNodeID ID;
3365	ID.AddPointer(Ptr: RD);
3366	ID.AddInteger(I: llvm::to_underlying(E: SM));
3367	ID.AddInteger(I: ConstArg);
3368	ID.AddInteger(I: VolatileArg);
3369	ID.AddInteger(I: RValueThis);
3370	ID.AddInteger(I: ConstThis);
3371	ID.AddInteger(I: VolatileThis);
3372
3373	void *InsertPoint;
3374	SpecialMemberOverloadResultEntry *Result =
3375	SpecialMemberCache.FindNodeOrInsertPos(ID, InsertPos&: InsertPoint);
3376
3377	// This was already cached
3378	if (Result)
3379	return *Result;
3380
3381	Result = BumpAlloc.Allocate<SpecialMemberOverloadResultEntry>();
3382	Result = new (Result) SpecialMemberOverloadResultEntry(ID);
3383	SpecialMemberCache.InsertNode(N: Result, InsertPos: InsertPoint);
3384
3385	if (SM == CXXSpecialMemberKind::Destructor) {
3386	if (RD->needsImplicitDestructor()) {
3387	runWithSufficientStackSpace(Loc: RD->getLocation(), Fn: [&] {
3388	DeclareImplicitDestructor(ClassDecl: RD);
3389	});
3390	}
3391	CXXDestructorDecl *DD = RD->getDestructor();
3392	Result->setMethod(DD);
3393	Result->setKind(DD && !DD->isDeleted()
3394	? SpecialMemberOverloadResult::Success
3395	: SpecialMemberOverloadResult::NoMemberOrDeleted);
3396	return *Result;
3397	}
3398
3399	// Prepare for overload resolution. Here we construct a synthetic argument
3400	// if necessary and make sure that implicit functions are declared.
3401	CanQualType CanTy = Context.getCanonicalType(T: Context.getTagDeclType(RD));
3402	DeclarationName Name;
3403	Expr *Arg = nullptr;
3404	unsigned NumArgs;
3405
3406	QualType ArgType = CanTy;
3407	ExprValueKind VK = VK_LValue;
3408
3409	if (SM == CXXSpecialMemberKind::DefaultConstructor) {
3410	Name = Context.DeclarationNames.getCXXConstructorName(Ty: CanTy);
3411	NumArgs = 0;
3412	if (RD->needsImplicitDefaultConstructor()) {
3413	runWithSufficientStackSpace(Loc: RD->getLocation(), Fn: [&] {
3414	DeclareImplicitDefaultConstructor(ClassDecl: RD);
3415	});
3416	}
3417	} else {
3418	if (SM == CXXSpecialMemberKind::CopyConstructor ||
3419	SM == CXXSpecialMemberKind::MoveConstructor) {
3420	Name = Context.DeclarationNames.getCXXConstructorName(Ty: CanTy);
3421	if (RD->needsImplicitCopyConstructor()) {
3422	runWithSufficientStackSpace(Loc: RD->getLocation(), Fn: [&] {
3423	DeclareImplicitCopyConstructor(ClassDecl: RD);
3424	});
3425	}
3426	if (getLangOpts().CPlusPlus11 && RD->needsImplicitMoveConstructor()) {
3427	runWithSufficientStackSpace(Loc: RD->getLocation(), Fn: [&] {
3428	DeclareImplicitMoveConstructor(ClassDecl: RD);
3429	});
3430	}
3431	} else {
3432	Name = Context.DeclarationNames.getCXXOperatorName(Op: OO_Equal);
3433	if (RD->needsImplicitCopyAssignment()) {
3434	runWithSufficientStackSpace(Loc: RD->getLocation(), Fn: [&] {
3435	DeclareImplicitCopyAssignment(ClassDecl: RD);
3436	});
3437	}
3438	if (getLangOpts().CPlusPlus11 && RD->needsImplicitMoveAssignment()) {
3439	runWithSufficientStackSpace(Loc: RD->getLocation(), Fn: [&] {
3440	DeclareImplicitMoveAssignment(ClassDecl: RD);
3441	});
3442	}
3443	}
3444
3445	if (ConstArg)
3446	ArgType.addConst();
3447	if (VolatileArg)
3448	ArgType.addVolatile();
3449
3450	// This isn't /really/ specified by the standard, but it's implied
3451	// we should be working from a PRValue in the case of move to ensure
3452	// that we prefer to bind to rvalue references, and an LValue in the
3453	// case of copy to ensure we don't bind to rvalue references.
3454	// Possibly an XValue is actually correct in the case of move, but
3455	// there is no semantic difference for class types in this restricted
3456	// case.
3457	if (SM == CXXSpecialMemberKind::CopyConstructor ||
3458	SM == CXXSpecialMemberKind::CopyAssignment)
3459	VK = VK_LValue;
3460	else
3461	VK = VK_PRValue;
3462	}
3463
3464	OpaqueValueExpr FakeArg(LookupLoc, ArgType, VK);
3465
3466	if (SM != CXXSpecialMemberKind::DefaultConstructor) {
3467	NumArgs = 1;
3468	Arg = &FakeArg;
3469	}
3470
3471	// Create the object argument
3472	QualType ThisTy = CanTy;
3473	if (ConstThis)
3474	ThisTy.addConst();
3475	if (VolatileThis)
3476	ThisTy.addVolatile();
3477	Expr::Classification Classification =
3478	OpaqueValueExpr(LookupLoc, ThisTy, RValueThis ? VK_PRValue : VK_LValue)
3479	.Classify(Context);
3480
3481	// Now we perform lookup on the name we computed earlier and do overload
3482	// resolution. Lookup is only performed directly into the class since there
3483	// will always be a (possibly implicit) declaration to shadow any others.
3484	OverloadCandidateSet OCS(LookupLoc, OverloadCandidateSet::CSK_Normal);
3485	DeclContext::lookup_result R = RD->lookup(Name);
3486
3487	if (R.empty()) {
3488	// We might have no default constructor because we have a lambda's closure
3489	// type, rather than because there's some other declared constructor.
3490	// Every class has a copy/move constructor, copy/move assignment, and
3491	// destructor.
3492	assert(SM == CXXSpecialMemberKind::DefaultConstructor &&
3493	"lookup for a constructor or assignment operator was empty");
3494	Result->setMethod(nullptr);
3495	Result->setKind(SpecialMemberOverloadResult::NoMemberOrDeleted);
3496	return *Result;
3497	}
3498
3499	// Copy the candidates as our processing of them may load new declarations
3500	// from an external source and invalidate lookup_result.
3501	SmallVector<NamedDecl *, 8> Candidates(R.begin(), R.end());
3502
3503	for (NamedDecl *CandDecl : Candidates) {
3504	if (CandDecl->isInvalidDecl())
3505	continue;
3506
3507	DeclAccessPair Cand = DeclAccessPair::make(CandDecl, AS_public);
3508	auto CtorInfo = getConstructorInfo(Cand);
3509	if (CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(Cand->getUnderlyingDecl())) {
3510	if (SM == CXXSpecialMemberKind::CopyAssignment ||
3511	SM == CXXSpecialMemberKind::MoveAssignment)
3512	AddMethodCandidate(M, Cand, RD, ThisTy, Classification,
3513	llvm::ArrayRef(&Arg, NumArgs), OCS, true);
3514	else if (CtorInfo)
3515	AddOverloadCandidate(CtorInfo.Constructor, CtorInfo.FoundDecl,
3516	llvm::ArrayRef(&Arg, NumArgs), OCS,
3517	/*SuppressUserConversions*/ true);
3518	else
3519	AddOverloadCandidate(M, Cand, llvm::ArrayRef(&Arg, NumArgs), OCS,
3520	/*SuppressUserConversions*/ true);
3521	} else if (FunctionTemplateDecl *Tmpl =
3522	dyn_cast<FunctionTemplateDecl>(Cand->getUnderlyingDecl())) {
3523	if (SM == CXXSpecialMemberKind::CopyAssignment ||
3524	SM == CXXSpecialMemberKind::MoveAssignment)
3525	AddMethodTemplateCandidate(Tmpl, Cand, RD, nullptr, ThisTy,
3526	Classification,
3527	llvm::ArrayRef(&Arg, NumArgs), OCS, true);
3528	else if (CtorInfo)
3529	AddTemplateOverloadCandidate(CtorInfo.ConstructorTmpl,
3530	CtorInfo.FoundDecl, nullptr,
3531	llvm::ArrayRef(&Arg, NumArgs), OCS, true);
3532	else
3533	AddTemplateOverloadCandidate(Tmpl, Cand, nullptr,
3534	llvm::ArrayRef(&Arg, NumArgs), OCS, true);
3535	} else {
3536	assert(isa<UsingDecl>(Cand.getDecl()) &&
3537	"illegal Kind of operator = Decl");
3538	}
3539	}
3540
3541	OverloadCandidateSet::iterator Best;
3542	switch (OCS.BestViableFunction(S&: *this, Loc: LookupLoc, Best)) {
3543	case OR_Success:
3544	Result->setMethod(cast<CXXMethodDecl>(Val: Best->Function));
3545	Result->setKind(SpecialMemberOverloadResult::Success);
3546	break;
3547
3548	case OR_Deleted:
3549	Result->setMethod(cast<CXXMethodDecl>(Val: Best->Function));
3550	Result->setKind(SpecialMemberOverloadResult::NoMemberOrDeleted);
3551	break;
3552
3553	case OR_Ambiguous:
3554	Result->setMethod(nullptr);
3555	Result->setKind(SpecialMemberOverloadResult::Ambiguous);
3556	break;
3557
3558	case OR_No_Viable_Function:
3559	Result->setMethod(nullptr);
3560	Result->setKind(SpecialMemberOverloadResult::NoMemberOrDeleted);
3561	break;
3562	}
3563
3564	return *Result;
3565	}
3566
3567	/// Look up the default constructor for the given class.
3568	CXXConstructorDecl *Sema::LookupDefaultConstructor(CXXRecordDecl *Class) {
3569	SpecialMemberOverloadResult Result =
3570	LookupSpecialMember(RD: Class, SM: CXXSpecialMemberKind::DefaultConstructor,
3571	ConstArg: false, VolatileArg: false, RValueThis: false, ConstThis: false, VolatileThis: false);
3572
3573	return cast_or_null<CXXConstructorDecl>(Val: Result.getMethod());
3574	}
3575
3576	/// Look up the copying constructor for the given class.
3577	CXXConstructorDecl *Sema::LookupCopyingConstructor(CXXRecordDecl *Class,
3578	unsigned Quals) {
3579	assert(!(Quals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&
3580	"non-const, non-volatile qualifiers for copy ctor arg");
3581	SpecialMemberOverloadResult Result = LookupSpecialMember(
3582	RD: Class, SM: CXXSpecialMemberKind::CopyConstructor, ConstArg: Quals & Qualifiers::Const,
3583	VolatileArg: Quals & Qualifiers::Volatile, RValueThis: false, ConstThis: false, VolatileThis: false);
3584
3585	return cast_or_null<CXXConstructorDecl>(Val: Result.getMethod());
3586	}
3587
3588	/// Look up the moving constructor for the given class.
3589	CXXConstructorDecl *Sema::LookupMovingConstructor(CXXRecordDecl *Class,
3590	unsigned Quals) {
3591	SpecialMemberOverloadResult Result = LookupSpecialMember(
3592	RD: Class, SM: CXXSpecialMemberKind::MoveConstructor, ConstArg: Quals & Qualifiers::Const,
3593	VolatileArg: Quals & Qualifiers::Volatile, RValueThis: false, ConstThis: false, VolatileThis: false);
3594
3595	return cast_or_null<CXXConstructorDecl>(Val: Result.getMethod());
3596	}
3597
3598	/// Look up the constructors for the given class.
3599	DeclContext::lookup_result Sema::LookupConstructors(CXXRecordDecl *Class) {
3600	// If the implicit constructors have not yet been declared, do so now.
3601	if (CanDeclareSpecialMemberFunction(Class)) {
3602	runWithSufficientStackSpace(Loc: Class->getLocation(), Fn: [&] {
3603	if (Class->needsImplicitDefaultConstructor())
3604	DeclareImplicitDefaultConstructor(ClassDecl: Class);
3605	if (Class->needsImplicitCopyConstructor())
3606	DeclareImplicitCopyConstructor(ClassDecl: Class);
3607	if (getLangOpts().CPlusPlus11 && Class->needsImplicitMoveConstructor())
3608	DeclareImplicitMoveConstructor(ClassDecl: Class);
3609	});
3610	}
3611
3612	CanQualType T = Context.getCanonicalType(T: Context.getTypeDeclType(Class));
3613	DeclarationName Name = Context.DeclarationNames.getCXXConstructorName(Ty: T);
3614	return Class->lookup(Name);
3615	}
3616
3617	/// Look up the copying assignment operator for the given class.
3618	CXXMethodDecl *Sema::LookupCopyingAssignment(CXXRecordDecl *Class,
3619	unsigned Quals, bool RValueThis,
3620	unsigned ThisQuals) {
3621	assert(!(Quals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&
3622	"non-const, non-volatile qualifiers for copy assignment arg");
3623	assert(!(ThisQuals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&
3624	"non-const, non-volatile qualifiers for copy assignment this");
3625	SpecialMemberOverloadResult Result = LookupSpecialMember(
3626	RD: Class, SM: CXXSpecialMemberKind::CopyAssignment, ConstArg: Quals & Qualifiers::Const,
3627	VolatileArg: Quals & Qualifiers::Volatile, RValueThis, ConstThis: ThisQuals & Qualifiers::Const,
3628	VolatileThis: ThisQuals & Qualifiers::Volatile);
3629
3630	return Result.getMethod();
3631	}
3632
3633	/// Look up the moving assignment operator for the given class.
3634	CXXMethodDecl *Sema::LookupMovingAssignment(CXXRecordDecl *Class,
3635	unsigned Quals,
3636	bool RValueThis,
3637	unsigned ThisQuals) {
3638	assert(!(ThisQuals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&
3639	"non-const, non-volatile qualifiers for copy assignment this");
3640	SpecialMemberOverloadResult Result = LookupSpecialMember(
3641	RD: Class, SM: CXXSpecialMemberKind::MoveAssignment, ConstArg: Quals & Qualifiers::Const,
3642	VolatileArg: Quals & Qualifiers::Volatile, RValueThis, ConstThis: ThisQuals & Qualifiers::Const,
3643	VolatileThis: ThisQuals & Qualifiers::Volatile);
3644
3645	return Result.getMethod();
3646	}
3647
3648	/// Look for the destructor of the given class.
3649	///
3650	/// During semantic analysis, this routine should be used in lieu of
3651	/// CXXRecordDecl::getDestructor().
3652	///
3653	/// \returns The destructor for this class.
3654	CXXDestructorDecl *Sema::LookupDestructor(CXXRecordDecl *Class) {
3655	return cast_or_null<CXXDestructorDecl>(
3656	Val: LookupSpecialMember(RD: Class, SM: CXXSpecialMemberKind::Destructor, ConstArg: false, VolatileArg: false,
3657	RValueThis: false, ConstThis: false, VolatileThis: false)
3658	.getMethod());
3659	}
3660
3661	/// LookupLiteralOperator - Determine which literal operator should be used for
3662	/// a user-defined literal, per C++11 [lex.ext].
3663	///
3664	/// Normal overload resolution is not used to select which literal operator to
3665	/// call for a user-defined literal. Look up the provided literal operator name,
3666	/// and filter the results to the appropriate set for the given argument types.
3667	Sema::LiteralOperatorLookupResult
3668	Sema::LookupLiteralOperator(Scope *S, LookupResult &R,
3669	ArrayRef<QualType> ArgTys, bool AllowRaw,
3670	bool AllowTemplate, bool AllowStringTemplatePack,
3671	bool DiagnoseMissing, StringLiteral *StringLit) {
3672	LookupName(R, S);
3673	assert(R.getResultKind() != LookupResult::Ambiguous &&
3674	"literal operator lookup can't be ambiguous");
3675
3676	// Filter the lookup results appropriately.
3677	LookupResult::Filter F = R.makeFilter();
3678
3679	bool AllowCooked = true;
3680	bool FoundRaw = false;
3681	bool FoundTemplate = false;
3682	bool FoundStringTemplatePack = false;
3683	bool FoundCooked = false;
3684
3685	while (F.hasNext()) {
3686	Decl *D = F.next();
3687	if (UsingShadowDecl *USD = dyn_cast<UsingShadowDecl>(Val: D))
3688	D = USD->getTargetDecl();
3689
3690	// If the declaration we found is invalid, skip it.
3691	if (D->isInvalidDecl()) {
3692	F.erase();
3693	continue;
3694	}
3695
3696	bool IsRaw = false;
3697	bool IsTemplate = false;
3698	bool IsStringTemplatePack = false;
3699	bool IsCooked = false;
3700
3701	if (FunctionDecl *FD = dyn_cast<FunctionDecl>(Val: D)) {
3702	if (FD->getNumParams() == 1 &&
3703	FD->getParamDecl(i: 0)->getType()->getAs<PointerType>())
3704	IsRaw = true;
3705	else if (FD->getNumParams() == ArgTys.size()) {
3706	IsCooked = true;
3707	for (unsigned ArgIdx = 0; ArgIdx != ArgTys.size(); ++ArgIdx) {
3708	QualType ParamTy = FD->getParamDecl(i: ArgIdx)->getType();
3709	if (!Context.hasSameUnqualifiedType(T1: ArgTys[ArgIdx], T2: ParamTy)) {
3710	IsCooked = false;
3711	break;
3712	}
3713	}
3714	}
3715	}
3716	if (FunctionTemplateDecl *FD = dyn_cast<FunctionTemplateDecl>(Val: D)) {
3717	TemplateParameterList *Params = FD->getTemplateParameters();
3718	if (Params->size() == 1) {
3719	IsTemplate = true;
3720	if (!Params->getParam(Idx: 0)->isTemplateParameterPack() && !StringLit) {
3721	// Implied but not stated: user-defined integer and floating literals
3722	// only ever use numeric literal operator templates, not templates
3723	// taking a parameter of class type.
3724	F.erase();
3725	continue;
3726	}
3727
3728	// A string literal template is only considered if the string literal
3729	// is a well-formed template argument for the template parameter.
3730	if (StringLit) {
3731	SFINAETrap Trap(*this);
3732	SmallVector<TemplateArgument, 1> SugaredChecked, CanonicalChecked;
3733	TemplateArgumentLoc Arg(TemplateArgument(StringLit), StringLit);
3734	if (CheckTemplateArgument(
3735	Params->getParam(Idx: 0), Arg, FD, R.getNameLoc(), R.getNameLoc(),
3736	0, SugaredChecked, CanonicalChecked, CTAK_Specified) ||
3737	Trap.hasErrorOccurred())
3738	IsTemplate = false;
3739	}
3740	} else {
3741	IsStringTemplatePack = true;
3742	}
3743	}
3744
3745	if (AllowTemplate && StringLit && IsTemplate) {
3746	FoundTemplate = true;
3747	AllowRaw = false;
3748	AllowCooked = false;
3749	AllowStringTemplatePack = false;
3750	if (FoundRaw || FoundCooked || FoundStringTemplatePack) {
3751	F.restart();
3752	FoundRaw = FoundCooked = FoundStringTemplatePack = false;
3753	}
3754	} else if (AllowCooked && IsCooked) {
3755	FoundCooked = true;
3756	AllowRaw = false;
3757	AllowTemplate = StringLit;
3758	AllowStringTemplatePack = false;
3759	if (FoundRaw || FoundTemplate || FoundStringTemplatePack) {
3760	// Go through again and remove the raw and template decls we've
3761	// already found.
3762	F.restart();
3763	FoundRaw = FoundTemplate = FoundStringTemplatePack = false;
3764	}
3765	} else if (AllowRaw && IsRaw) {
3766	FoundRaw = true;
3767	} else if (AllowTemplate && IsTemplate) {
3768	FoundTemplate = true;
3769	} else if (AllowStringTemplatePack && IsStringTemplatePack) {
3770	FoundStringTemplatePack = true;
3771	} else {
3772	F.erase();
3773	}
3774	}
3775
3776	F.done();
3777
3778	// Per C++20 [lex.ext]p5, we prefer the template form over the non-template
3779	// form for string literal operator templates.
3780	if (StringLit && FoundTemplate)
3781	return LOLR_Template;
3782
3783	// C++11 [lex.ext]p3, p4: If S contains a literal operator with a matching
3784	// parameter type, that is used in preference to a raw literal operator
3785	// or literal operator template.
3786	if (FoundCooked)
3787	return LOLR_Cooked;
3788
3789	// C++11 [lex.ext]p3, p4: S shall contain a raw literal operator or a literal
3790	// operator template, but not both.
3791	if (FoundRaw && FoundTemplate) {
3792	Diag(R.getNameLoc(), diag::err_ovl_ambiguous_call) << R.getLookupName();
3793	for (const NamedDecl *D : R)
3794	NoteOverloadCandidate(Found: D, Fn: D->getUnderlyingDecl()->getAsFunction());
3795	return LOLR_Error;
3796	}
3797
3798	if (FoundRaw)
3799	return LOLR_Raw;
3800
3801	if (FoundTemplate)
3802	return LOLR_Template;
3803
3804	if (FoundStringTemplatePack)
3805	return LOLR_StringTemplatePack;
3806
3807	// Didn't find anything we could use.
3808	if (DiagnoseMissing) {
3809	Diag(R.getNameLoc(), diag::err_ovl_no_viable_literal_operator)
3810	<< R.getLookupName() << (int)ArgTys.size() << ArgTys[0]
3811	<< (ArgTys.size() == 2 ? ArgTys[1] : QualType()) << AllowRaw
3812	<< (AllowTemplate || AllowStringTemplatePack);
3813	return LOLR_Error;
3814	}
3815
3816	return LOLR_ErrorNoDiagnostic;
3817	}
3818
3819	void ADLResult::insert(NamedDecl *New) {
3820	NamedDecl *&Old = Decls[cast<NamedDecl>(New->getCanonicalDecl())];
3821
3822	// If we haven't yet seen a decl for this key, or the last decl
3823	// was exactly this one, we're done.
3824	if (Old == nullptr || Old == New) {
3825	Old = New;
3826	return;
3827	}
3828
3829	// Otherwise, decide which is a more recent redeclaration.
3830	FunctionDecl *OldFD = Old->getAsFunction();
3831	FunctionDecl *NewFD = New->getAsFunction();
3832
3833	FunctionDecl *Cursor = NewFD;
3834	while (true) {
3835	Cursor = Cursor->getPreviousDecl();
3836
3837	// If we got to the end without finding OldFD, OldFD is the newer
3838	// declaration; leave things as they are.
3839	if (!Cursor) return;
3840
3841	// If we do find OldFD, then NewFD is newer.
3842	if (Cursor == OldFD) break;
3843
3844	// Otherwise, keep looking.
3845	}
3846
3847	Old = New;
3848	}
3849
3850	void Sema::ArgumentDependentLookup(DeclarationName Name, SourceLocation Loc,
3851	ArrayRef<Expr *> Args, ADLResult &Result) {
3852	// Find all of the associated namespaces and classes based on the
3853	// arguments we have.
3854	AssociatedNamespaceSet AssociatedNamespaces;
3855	AssociatedClassSet AssociatedClasses;
3856	FindAssociatedClassesAndNamespaces(InstantiationLoc: Loc, Args,
3857	AssociatedNamespaces,
3858	AssociatedClasses);
3859
3860	// C++ [basic.lookup.argdep]p3:
3861	// Let X be the lookup set produced by unqualified lookup (3.4.1)
3862	// and let Y be the lookup set produced by argument dependent
3863	// lookup (defined as follows). If X contains [...] then Y is
3864	// empty. Otherwise Y is the set of declarations found in the
3865	// namespaces associated with the argument types as described
3866	// below. The set of declarations found by the lookup of the name
3867	// is the union of X and Y.
3868	//
3869	// Here, we compute Y and add its members to the overloaded
3870	// candidate set.
3871	for (auto *NS : AssociatedNamespaces) {
3872	// When considering an associated namespace, the lookup is the
3873	// same as the lookup performed when the associated namespace is
3874	// used as a qualifier (3.4.3.2) except that:
3875	//
3876	// -- Any using-directives in the associated namespace are
3877	// ignored.
3878	//
3879	// -- Any namespace-scope friend functions declared in
3880	// associated classes are visible within their respective
3881	// namespaces even if they are not visible during an ordinary
3882	// lookup (11.4).
3883	//
3884	// C++20 [basic.lookup.argdep] p4.3
3885	// -- are exported, are attached to a named module M, do not appear
3886	// in the translation unit containing the point of the lookup, and
3887	// have the same innermost enclosing non-inline namespace scope as
3888	// a declaration of an associated entity attached to M.
3889	DeclContext::lookup_result R = NS->lookup(Name);
3890	for (auto *D : R) {
3891	auto *Underlying = D;
3892	if (auto *USD = dyn_cast<UsingShadowDecl>(Val: D))
3893	Underlying = USD->getTargetDecl();
3894
3895	if (!isa<FunctionDecl>(Val: Underlying) &&
3896	!isa<FunctionTemplateDecl>(Val: Underlying))
3897	continue;
3898
3899	// The declaration is visible to argument-dependent lookup if either
3900	// it's ordinarily visible or declared as a friend in an associated
3901	// class.
3902	bool Visible = false;
3903	for (D = D->getMostRecentDecl(); D;
3904	D = cast_or_null<NamedDecl>(D->getPreviousDecl())) {
3905	if (D->getIdentifierNamespace() & Decl::IDNS_Ordinary) {
3906	if (isVisible(D)) {
3907	Visible = true;
3908	break;
3909	}
3910
3911	if (!getLangOpts().CPlusPlusModules)
3912	continue;
3913
3914	if (D->isInExportDeclContext()) {
3915	Module *FM = D->getOwningModule();
3916	// C++20 [basic.lookup.argdep] p4.3 .. are exported ...
3917	// exports are only valid in module purview and outside of any
3918	// PMF (although a PMF should not even be present in a module
3919	// with an import).
3920	assert(FM && FM->isNamedModule() && !FM->isPrivateModule() &&
3921	"bad export context");
3922	// .. are attached to a named module M, do not appear in the
3923	// translation unit containing the point of the lookup..
3924	if (D->isInAnotherModuleUnit() &&
3925	llvm::any_of(Range&: AssociatedClasses, P: [&](auto *E) {
3926	// ... and have the same innermost enclosing non-inline
3927	// namespace scope as a declaration of an associated entity
3928	// attached to M
3929	if (E->getOwningModule() != FM)
3930	return false;
3931	// TODO: maybe this could be cached when generating the
3932	// associated namespaces / entities.
3933	DeclContext *Ctx = E->getDeclContext();
3934	while (!Ctx->isFileContext() || Ctx->isInlineNamespace())
3935	Ctx = Ctx->getParent();
3936	return Ctx == NS;
3937	})) {
3938	Visible = true;
3939	break;
3940	}
3941	}
3942	} else if (D->getFriendObjectKind()) {
3943	auto *RD = cast<CXXRecordDecl>(D->getLexicalDeclContext());
3944	// [basic.lookup.argdep]p4:
3945	// Argument-dependent lookup finds all declarations of functions and
3946	// function templates that
3947	// - ...
3948	// - are declared as a friend ([class.friend]) of any class with a
3949	// reachable definition in the set of associated entities,
3950	//
3951	// FIXME: If there's a merged definition of D that is reachable, then
3952	// the friend declaration should be considered.
3953	if (AssociatedClasses.count(key: RD) && isReachable(D)) {
3954	Visible = true;
3955	break;
3956	}
3957	}
3958	}
3959
3960	// FIXME: Preserve D as the FoundDecl.
3961	if (Visible)
3962	Result.insert(New: Underlying);
3963	}
3964	}
3965	}
3966
3967	//----------------------------------------------------------------------------
3968	// Search for all visible declarations.
3969	//----------------------------------------------------------------------------
3970	VisibleDeclConsumer::~VisibleDeclConsumer() { }
3971
3972	bool VisibleDeclConsumer::includeHiddenDecls() const { return false; }
3973
3974	namespace {
3975
3976	class ShadowContextRAII;
3977
3978	class VisibleDeclsRecord {
3979	public:
3980	/// An entry in the shadow map, which is optimized to store a
3981	/// single declaration (the common case) but can also store a list
3982	/// of declarations.
3983	typedef llvm::TinyPtrVector<NamedDecl*> ShadowMapEntry;
3984
3985	private:
3986	/// A mapping from declaration names to the declarations that have
3987	/// this name within a particular scope.
3988	typedef llvm::DenseMap<DeclarationName, ShadowMapEntry> ShadowMap;
3989
3990	/// A list of shadow maps, which is used to model name hiding.
3991	std::list<ShadowMap> ShadowMaps;
3992
3993	/// The declaration contexts we have already visited.
3994	llvm::SmallPtrSet<DeclContext *, 8> VisitedContexts;
3995
3996	friend class ShadowContextRAII;
3997
3998	public:
3999	/// Determine whether we have already visited this context
4000	/// (and, if not, note that we are going to visit that context now).
4001	bool visitedContext(DeclContext *Ctx) {
4002	return !VisitedContexts.insert(Ptr: Ctx).second;
4003	}
4004
4005	bool alreadyVisitedContext(DeclContext *Ctx) {
4006	return VisitedContexts.count(Ptr: Ctx);
4007	}
4008
4009	/// Determine whether the given declaration is hidden in the
4010	/// current scope.
4011	///
4012	/// \returns the declaration that hides the given declaration, or
4013	/// NULL if no such declaration exists.
4014	NamedDecl *checkHidden(NamedDecl *ND);
4015
4016	/// Add a declaration to the current shadow map.
4017	void add(NamedDecl *ND) {
4018	ShadowMaps.back()[ND->getDeclName()].push_back(NewVal: ND);
4019	}
4020	};
4021
4022	/// RAII object that records when we've entered a shadow context.
4023	class ShadowContextRAII {
4024	VisibleDeclsRecord &Visible;
4025
4026	typedef VisibleDeclsRecord::ShadowMap ShadowMap;
4027
4028	public:
4029	ShadowContextRAII(VisibleDeclsRecord &Visible) : Visible(Visible) {
4030	Visible.ShadowMaps.emplace_back();
4031	}
4032
4033	~ShadowContextRAII() {
4034	Visible.ShadowMaps.pop_back();
4035	}
4036	};
4037
4038	} // end anonymous namespace
4039
4040	NamedDecl *VisibleDeclsRecord::checkHidden(NamedDecl *ND) {
4041	unsigned IDNS = ND->getIdentifierNamespace();
4042	std::list<ShadowMap>::reverse_iterator SM = ShadowMaps.rbegin();
4043	for (std::list<ShadowMap>::reverse_iterator SMEnd = ShadowMaps.rend();
4044	SM != SMEnd; ++SM) {
4045	ShadowMap::iterator Pos = SM->find(Val: ND->getDeclName());
4046	if (Pos == SM->end())
4047	continue;
4048
4049	for (auto *D : Pos->second) {
4050	// A tag declaration does not hide a non-tag declaration.
4051	if (D->hasTagIdentifierNamespace() &&
4052	(IDNS & (Decl::IDNS_Member | Decl::IDNS_Ordinary |
4053	Decl::IDNS_ObjCProtocol)))
4054	continue;
4055
4056	// Protocols are in distinct namespaces from everything else.
4057	if (((D->getIdentifierNamespace() & Decl::IDNS_ObjCProtocol)
4058	|| (IDNS & Decl::IDNS_ObjCProtocol)) &&
4059	D->getIdentifierNamespace() != IDNS)
4060	continue;
4061
4062	// Functions and function templates in the same scope overload
4063	// rather than hide. FIXME: Look for hiding based on function
4064	// signatures!
4065	if (D->getUnderlyingDecl()->isFunctionOrFunctionTemplate() &&
4066	ND->getUnderlyingDecl()->isFunctionOrFunctionTemplate() &&
4067	SM == ShadowMaps.rbegin())
4068	continue;
4069
4070	// A shadow declaration that's created by a resolved using declaration
4071	// is not hidden by the same using declaration.
4072	if (isa<UsingShadowDecl>(Val: ND) && isa<UsingDecl>(Val: D) &&
4073	cast<UsingShadowDecl>(Val: ND)->getIntroducer() == D)
4074	continue;
4075
4076	// We've found a declaration that hides this one.
4077	return D;
4078	}
4079	}
4080
4081	return nullptr;
4082	}
4083
4084	namespace {
4085	class LookupVisibleHelper {
4086	public:
4087	LookupVisibleHelper(VisibleDeclConsumer &Consumer, bool IncludeDependentBases,
4088	bool LoadExternal)
4089	: Consumer(Consumer), IncludeDependentBases(IncludeDependentBases),
4090	LoadExternal(LoadExternal) {}
4091
4092	void lookupVisibleDecls(Sema &SemaRef, Scope *S, Sema::LookupNameKind Kind,
4093	bool IncludeGlobalScope) {
4094	// Determine the set of using directives available during
4095	// unqualified name lookup.
4096	Scope *Initial = S;
4097	UnqualUsingDirectiveSet UDirs(SemaRef);
4098	if (SemaRef.getLangOpts().CPlusPlus) {
4099	// Find the first namespace or translation-unit scope.
4100	while (S && !isNamespaceOrTranslationUnitScope(S))
4101	S = S->getParent();
4102
4103	UDirs.visitScopeChain(S: Initial, InnermostFileScope: S);
4104	}
4105	UDirs.done();
4106
4107	// Look for visible declarations.
4108	LookupResult Result(SemaRef, DeclarationName(), SourceLocation(), Kind);
4109	Result.setAllowHidden(Consumer.includeHiddenDecls());
4110	if (!IncludeGlobalScope)
4111	Visited.visitedContext(SemaRef.getASTContext().getTranslationUnitDecl());
4112	ShadowContextRAII Shadow(Visited);
4113	lookupInScope(S: Initial, Result, UDirs);
4114	}
4115
4116	void lookupVisibleDecls(Sema &SemaRef, DeclContext *Ctx,
4117	Sema::LookupNameKind Kind, bool IncludeGlobalScope) {
4118	LookupResult Result(SemaRef, DeclarationName(), SourceLocation(), Kind);
4119	Result.setAllowHidden(Consumer.includeHiddenDecls());
4120	if (!IncludeGlobalScope)
4121	Visited.visitedContext(SemaRef.getASTContext().getTranslationUnitDecl());
4122
4123	ShadowContextRAII Shadow(Visited);
4124	lookupInDeclContext(Ctx, Result, /*QualifiedNameLookup=*/true,
4125	/*InBaseClass=*/false);
4126	}
4127
4128	private:
4129	void lookupInDeclContext(DeclContext *Ctx, LookupResult &Result,
4130	bool QualifiedNameLookup, bool InBaseClass) {
4131	if (!Ctx)
4132	return;
4133
4134	// Make sure we don't visit the same context twice.
4135	if (Visited.visitedContext(Ctx: Ctx->getPrimaryContext()))
4136	return;
4137
4138	Consumer.EnteredContext(Ctx);
4139
4140	// Outside C++, lookup results for the TU live on identifiers.
4141	if (isa<TranslationUnitDecl>(Val: Ctx) &&
4142	!Result.getSema().getLangOpts().CPlusPlus) {
4143	auto &S = Result.getSema();
4144	auto &Idents = S.Context.Idents;
4145
4146	// Ensure all external identifiers are in the identifier table.
4147	if (LoadExternal)
4148	if (IdentifierInfoLookup *External =
4149	Idents.getExternalIdentifierLookup()) {
4150	std::unique_ptr<IdentifierIterator> Iter(External->getIdentifiers());
4151	for (StringRef Name = Iter->Next(); !Name.empty();
4152	Name = Iter->Next())
4153	Idents.get(Name);
4154	}
4155
4156	// Walk all lookup results in the TU for each identifier.
4157	for (const auto &Ident : Idents) {
4158	for (auto I = S.IdResolver.begin(Ident.getValue()),
4159	E = S.IdResolver.end();
4160	I != E; ++I) {
4161	if (S.IdResolver.isDeclInScope(*I, Ctx)) {
4162	if (NamedDecl *ND = Result.getAcceptableDecl(*I)) {
4163	Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
4164	Visited.add(ND);
4165	}
4166	}
4167	}
4168	}
4169
4170	return;
4171	}
4172
4173	if (CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(Val: Ctx))
4174	Result.getSema().ForceDeclarationOfImplicitMembers(Class);
4175
4176	llvm::SmallVector<NamedDecl *, 4> DeclsToVisit;
4177	// We sometimes skip loading namespace-level results (they tend to be huge).
4178	bool Load = LoadExternal ||
4179	!(isa<TranslationUnitDecl>(Val: Ctx) || isa<NamespaceDecl>(Val: Ctx));
4180	// Enumerate all of the results in this context.
4181	for (DeclContextLookupResult R :
4182	Load ? Ctx->lookups()
4183	: Ctx->noload_lookups(/*PreserveInternalState=*/false))
4184	for (auto *D : R)
4185	// Rather than visit immediately, we put ND into a vector and visit
4186	// all decls, in order, outside of this loop. The reason is that
4187	// Consumer.FoundDecl() and LookupResult::getAcceptableDecl(D)
4188	// may invalidate the iterators used in the two
4189	// loops above.
4190	DeclsToVisit.push_back(Elt: D);
4191
4192	for (auto *D : DeclsToVisit)
4193	if (auto *ND = Result.getAcceptableDecl(D)) {
4194	Consumer.FoundDecl(ND, Hiding: Visited.checkHidden(ND), Ctx, InBaseClass);
4195	Visited.add(ND);
4196	}
4197
4198	DeclsToVisit.clear();
4199
4200	// Traverse using directives for qualified name lookup.
4201	if (QualifiedNameLookup) {
4202	ShadowContextRAII Shadow(Visited);
4203	for (auto *I : Ctx->using_directives()) {
4204	if (!Result.getSema().isVisible(I))
4205	continue;
4206	lookupInDeclContext(I->getNominatedNamespace(), Result,
4207	QualifiedNameLookup, InBaseClass);
4208	}
4209	}
4210
4211	// Traverse the contexts of inherited C++ classes.
4212	if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Val: Ctx)) {
4213	if (!Record->hasDefinition())
4214	return;
4215
4216	for (const auto &B : Record->bases()) {
4217	QualType BaseType = B.getType();
4218
4219	RecordDecl *RD;
4220	if (BaseType->isDependentType()) {
4221	if (!IncludeDependentBases) {
4222	// Don't look into dependent bases, because name lookup can't look
4223	// there anyway.
4224	continue;
4225	}
4226	const auto *TST = BaseType->getAs<TemplateSpecializationType>();
4227	if (!TST)
4228	continue;
4229	TemplateName TN = TST->getTemplateName();
4230	const auto *TD =
4231	dyn_cast_or_null<ClassTemplateDecl>(Val: TN.getAsTemplateDecl());
4232	if (!TD)
4233	continue;
4234	RD = TD->getTemplatedDecl();
4235	} else {
4236	const auto *Record = BaseType->getAs<RecordType>();
4237	if (!Record)
4238	continue;
4239	RD = Record->getDecl();
4240	}
4241
4242	// FIXME: It would be nice to be able to determine whether referencing
4243	// a particular member would be ambiguous. For example, given
4244	//
4245	// struct A { int member; };
4246	// struct B { int member; };
4247	// struct C : A, B { };
4248	//
4249	// void f(C *c) { c->### }
4250	//
4251	// accessing 'member' would result in an ambiguity. However, we
4252	// could be smart enough to qualify the member with the base
4253	// class, e.g.,
4254	//
4255	// c->B::member
4256	//
4257	// or
4258	//
4259	// c->A::member
4260
4261	// Find results in this base class (and its bases).
4262	ShadowContextRAII Shadow(Visited);
4263	lookupInDeclContext(RD, Result, QualifiedNameLookup,
4264	/*InBaseClass=*/true);
4265	}
4266	}
4267
4268	// Traverse the contexts of Objective-C classes.
4269	if (ObjCInterfaceDecl *IFace = dyn_cast<ObjCInterfaceDecl>(Val: Ctx)) {
4270	// Traverse categories.
4271	for (auto *Cat : IFace->visible_categories()) {
4272	ShadowContextRAII Shadow(Visited);
4273	lookupInDeclContext(Cat, Result, QualifiedNameLookup,
4274	/*InBaseClass=*/false);
4275	}
4276
4277	// Traverse protocols.
4278	for (auto *I : IFace->all_referenced_protocols()) {
4279	ShadowContextRAII Shadow(Visited);
4280	lookupInDeclContext(I, Result, QualifiedNameLookup,
4281	/*InBaseClass=*/false);
4282	}
4283
4284	// Traverse the superclass.
4285	if (IFace->getSuperClass()) {
4286	ShadowContextRAII Shadow(Visited);
4287	lookupInDeclContext(IFace->getSuperClass(), Result, QualifiedNameLookup,
4288	/*InBaseClass=*/true);
4289	}
4290
4291	// If there is an implementation, traverse it. We do this to find
4292	// synthesized ivars.
4293	if (IFace->getImplementation()) {
4294	ShadowContextRAII Shadow(Visited);
4295	lookupInDeclContext(IFace->getImplementation(), Result,
4296	QualifiedNameLookup, InBaseClass);
4297	}
4298	} else if (ObjCProtocolDecl *Protocol = dyn_cast<ObjCProtocolDecl>(Val: Ctx)) {
4299	for (auto *I : Protocol->protocols()) {
4300	ShadowContextRAII Shadow(Visited);
4301	lookupInDeclContext(I, Result, QualifiedNameLookup,
4302	/*InBaseClass=*/false);
4303	}
4304	} else if (ObjCCategoryDecl *Category = dyn_cast<ObjCCategoryDecl>(Val: Ctx)) {
4305	for (auto *I : Category->protocols()) {
4306	ShadowContextRAII Shadow(Visited);
4307	lookupInDeclContext(I, Result, QualifiedNameLookup,
4308	/*InBaseClass=*/false);
4309	}
4310
4311	// If there is an implementation, traverse it.
4312	if (Category->getImplementation()) {
4313	ShadowContextRAII Shadow(Visited);
4314	lookupInDeclContext(Category->getImplementation(), Result,
4315	QualifiedNameLookup, /*InBaseClass=*/true);
4316	}
4317	}
4318	}
4319
4320	void lookupInScope(Scope *S, LookupResult &Result,
4321	UnqualUsingDirectiveSet &UDirs) {
4322	// No clients run in this mode and it's not supported. Please add tests and
4323	// remove the assertion if you start relying on it.
4324	assert(!IncludeDependentBases && "Unsupported flag for lookupInScope");
4325
4326	if (!S)
4327	return;
4328
4329	if (!S->getEntity() ||
4330	(!S->getParent() && !Visited.alreadyVisitedContext(Ctx: S->getEntity())) ||
4331	(S->getEntity())->isFunctionOrMethod()) {
4332	FindLocalExternScope FindLocals(Result);
4333	// Walk through the declarations in this Scope. The consumer might add new
4334	// decls to the scope as part of deserialization, so make a copy first.
4335	SmallVector<Decl *, 8> ScopeDecls(S->decls().begin(), S->decls().end());
4336	for (Decl *D : ScopeDecls) {
4337	if (NamedDecl *ND = dyn_cast<NamedDecl>(Val: D))
4338	if ((ND = Result.getAcceptableDecl(D: ND))) {
4339	Consumer.FoundDecl(ND, Hiding: Visited.checkHidden(ND), Ctx: nullptr, InBaseClass: false);
4340	Visited.add(ND);
4341	}
4342	}
4343	}
4344
4345	DeclContext *Entity = S->getLookupEntity();
4346	if (Entity) {
4347	// Look into this scope's declaration context, along with any of its
4348	// parent lookup contexts (e.g., enclosing classes), up to the point
4349	// where we hit the context stored in the next outer scope.
4350	DeclContext *OuterCtx = findOuterContext(S);
4351
4352	for (DeclContext *Ctx = Entity; Ctx && !Ctx->Equals(DC: OuterCtx);
4353	Ctx = Ctx->getLookupParent()) {
4354	if (ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(Val: Ctx)) {
4355	if (Method->isInstanceMethod()) {
4356	// For instance methods, look for ivars in the method's interface.
4357	LookupResult IvarResult(Result.getSema(), Result.getLookupName(),
4358	Result.getNameLoc(),
4359	Sema::LookupMemberName);
4360	if (ObjCInterfaceDecl *IFace = Method->getClassInterface()) {
4361	lookupInDeclContext(IFace, IvarResult,
4362	/*QualifiedNameLookup=*/false,
4363	/*InBaseClass=*/false);
4364	}
4365	}
4366
4367	// We've already performed all of the name lookup that we need
4368	// to for Objective-C methods; the next context will be the
4369	// outer scope.
4370	break;
4371	}
4372
4373	if (Ctx->isFunctionOrMethod())
4374	continue;
4375
4376	lookupInDeclContext(Ctx, Result, /*QualifiedNameLookup=*/false,
4377	/*InBaseClass=*/false);
4378	}
4379	} else if (!S->getParent()) {
4380	// Look into the translation unit scope. We walk through the translation
4381	// unit's declaration context, because the Scope itself won't have all of
4382	// the declarations if we loaded a precompiled header.
4383	// FIXME: We would like the translation unit's Scope object to point to
4384	// the translation unit, so we don't need this special "if" branch.
4385	// However, doing so would force the normal C++ name-lookup code to look
4386	// into the translation unit decl when the IdentifierInfo chains would
4387	// suffice. Once we fix that problem (which is part of a more general
4388	// "don't look in DeclContexts unless we have to" optimization), we can
4389	// eliminate this.
4390	Entity = Result.getSema().Context.getTranslationUnitDecl();
4391	lookupInDeclContext(Ctx: Entity, Result, /*QualifiedNameLookup=*/false,
4392	/*InBaseClass=*/false);
4393	}
4394
4395	if (Entity) {
4396	// Lookup visible declarations in any namespaces found by using
4397	// directives.
4398	for (const UnqualUsingEntry &UUE : UDirs.getNamespacesFor(Entity))
4399	lookupInDeclContext(
4400	const_cast<DeclContext *>(UUE.getNominatedNamespace()), Result,
4401	/*QualifiedNameLookup=*/false,
4402	/*InBaseClass=*/false);
4403	}
4404
4405	// Lookup names in the parent scope.
4406	ShadowContextRAII Shadow(Visited);
4407	lookupInScope(S: S->getParent(), Result, UDirs);
4408	}
4409
4410	private:
4411	VisibleDeclsRecord Visited;
4412	VisibleDeclConsumer &Consumer;
4413	bool IncludeDependentBases;
4414	bool LoadExternal;
4415	};
4416	} // namespace
4417
4418	void Sema::LookupVisibleDecls(Scope *S, LookupNameKind Kind,
4419	VisibleDeclConsumer &Consumer,
4420	bool IncludeGlobalScope, bool LoadExternal) {
4421	LookupVisibleHelper H(Consumer, /*IncludeDependentBases=*/false,
4422	LoadExternal);
4423	H.lookupVisibleDecls(SemaRef&: *this, S, Kind, IncludeGlobalScope);
4424	}
4425
4426	void Sema::LookupVisibleDecls(DeclContext *Ctx, LookupNameKind Kind,
4427	VisibleDeclConsumer &Consumer,
4428	bool IncludeGlobalScope,
4429	bool IncludeDependentBases, bool LoadExternal) {
4430	LookupVisibleHelper H(Consumer, IncludeDependentBases, LoadExternal);
4431	H.lookupVisibleDecls(SemaRef&: *this, Ctx, Kind, IncludeGlobalScope);
4432	}
4433
4434	/// LookupOrCreateLabel - Do a name lookup of a label with the specified name.
4435	/// If GnuLabelLoc is a valid source location, then this is a definition
4436	/// of an __label__ label name, otherwise it is a normal label definition
4437	/// or use.
4438	LabelDecl *Sema::LookupOrCreateLabel(IdentifierInfo *II, SourceLocation Loc,
4439	SourceLocation GnuLabelLoc) {
4440	// Do a lookup to see if we have a label with this name already.
4441	NamedDecl *Res = nullptr;
4442
4443	if (GnuLabelLoc.isValid()) {
4444	// Local label definitions always shadow existing labels.
4445	Res = LabelDecl::Create(C&: Context, DC: CurContext, IdentL: Loc, II, GnuLabelL: GnuLabelLoc);
4446	Scope *S = CurScope;
4447	PushOnScopeChains(D: Res, S, AddToContext: true);
4448	return cast<LabelDecl>(Val: Res);
4449	}
4450
4451	// Not a GNU local label.
4452	Res = LookupSingleName(S: CurScope, Name: II, Loc, NameKind: LookupLabel,
4453	Redecl: RedeclarationKind::NotForRedeclaration);
4454	// If we found a label, check to see if it is in the same context as us.
4455	// When in a Block, we don't want to reuse a label in an enclosing function.
4456	if (Res && Res->getDeclContext() != CurContext)
4457	Res = nullptr;
4458	if (!Res) {
4459	// If not forward referenced or defined already, create the backing decl.
4460	Res = LabelDecl::Create(C&: Context, DC: CurContext, IdentL: Loc, II);
4461	Scope *S = CurScope->getFnParent();
4462	assert(S && "Not in a function?");
4463	PushOnScopeChains(D: Res, S, AddToContext: true);
4464	}
4465	return cast<LabelDecl>(Val: Res);
4466	}
4467
4468	//===----------------------------------------------------------------------===//
4469	// Typo correction
4470	//===----------------------------------------------------------------------===//
4471
4472	static bool isCandidateViable(CorrectionCandidateCallback &CCC,
4473	TypoCorrection &Candidate) {
4474	Candidate.setCallbackDistance(CCC.RankCandidate(candidate: Candidate));
4475	return Candidate.getEditDistance(Normalized: false) != TypoCorrection::InvalidDistance;
4476	}
4477
4478	static void LookupPotentialTypoResult(Sema &SemaRef,
4479	LookupResult &Res,
4480	IdentifierInfo *Name,
4481	Scope *S, CXXScopeSpec *SS,
4482	DeclContext *MemberContext,
4483	bool EnteringContext,
4484	bool isObjCIvarLookup,
4485	bool FindHidden);
4486
4487	/// Check whether the declarations found for a typo correction are
4488	/// visible. Set the correction's RequiresImport flag to true if none of the
4489	/// declarations are visible, false otherwise.
4490	static void checkCorrectionVisibility(Sema &SemaRef, TypoCorrection &TC) {
4491	TypoCorrection::decl_iterator DI = TC.begin(), DE = TC.end();
4492
4493	for (/**/; DI != DE; ++DI)
4494	if (!LookupResult::isVisible(SemaRef, D: *DI))
4495	break;
4496	// No filtering needed if all decls are visible.
4497	if (DI == DE) {
4498	TC.setRequiresImport(false);
4499	return;
4500	}
4501
4502	llvm::SmallVector<NamedDecl*, 4> NewDecls(TC.begin(), DI);
4503	bool AnyVisibleDecls = !NewDecls.empty();
4504
4505	for (/**/; DI != DE; ++DI) {
4506	if (LookupResult::isVisible(SemaRef, D: *DI)) {
4507	if (!AnyVisibleDecls) {
4508	// Found a visible decl, discard all hidden ones.
4509	AnyVisibleDecls = true;
4510	NewDecls.clear();
4511	}
4512	NewDecls.push_back(Elt: *DI);
4513	} else if (!AnyVisibleDecls && !(*DI)->isModulePrivate())
4514	NewDecls.push_back(Elt: *DI);
4515	}
4516
4517	if (NewDecls.empty())
4518	TC = TypoCorrection();
4519	else {
4520	TC.setCorrectionDecls(NewDecls);
4521	TC.setRequiresImport(!AnyVisibleDecls);
4522	}
4523	}
4524
4525	// Fill the supplied vector with the IdentifierInfo pointers for each piece of
4526	// the given NestedNameSpecifier (i.e. given a NestedNameSpecifier "foo::bar::",
4527	// fill the vector with the IdentifierInfo pointers for "foo" and "bar").
4528	static void getNestedNameSpecifierIdentifiers(
4529	NestedNameSpecifier *NNS,
4530	SmallVectorImpl<const IdentifierInfo*> &Identifiers) {
4531	if (NestedNameSpecifier *Prefix = NNS->getPrefix())
4532	getNestedNameSpecifierIdentifiers(NNS: Prefix, Identifiers);
4533	else
4534	Identifiers.clear();
4535
4536	const IdentifierInfo *II = nullptr;
4537
4538	switch (NNS->getKind()) {
4539	case NestedNameSpecifier::Identifier:
4540	II = NNS->getAsIdentifier();
4541	break;
4542
4543	case NestedNameSpecifier::Namespace:
4544	if (NNS->getAsNamespace()->isAnonymousNamespace())
4545	return;
4546	II = NNS->getAsNamespace()->getIdentifier();
4547	break;
4548
4549	case NestedNameSpecifier::NamespaceAlias:
4550	II = NNS->getAsNamespaceAlias()->getIdentifier();
4551	break;
4552
4553	case NestedNameSpecifier::TypeSpecWithTemplate:
4554	case NestedNameSpecifier::TypeSpec:
4555	II = QualType(NNS->getAsType(), 0).getBaseTypeIdentifier();
4556	break;
4557
4558	case NestedNameSpecifier::Global:
4559	case NestedNameSpecifier::Super:
4560	return;
4561	}
4562
4563	if (II)
4564	Identifiers.push_back(Elt: II);
4565	}
4566
4567	void TypoCorrectionConsumer::FoundDecl(NamedDecl *ND, NamedDecl *Hiding,
4568	DeclContext *Ctx, bool InBaseClass) {
4569	// Don't consider hidden names for typo correction.
4570	if (Hiding)
4571	return;
4572
4573	// Only consider entities with identifiers for names, ignoring
4574	// special names (constructors, overloaded operators, selectors,
4575	// etc.).
4576	IdentifierInfo *Name = ND->getIdentifier();
4577	if (!Name)
4578	return;
4579
4580	// Only consider visible declarations and declarations from modules with
4581	// names that exactly match.
4582	if (!LookupResult::isVisible(SemaRef, D: ND) && Name != Typo)
4583	return;
4584
4585	FoundName(Name: Name->getName());
4586	}
4587
4588	void TypoCorrectionConsumer::FoundName(StringRef Name) {
4589	// Compute the edit distance between the typo and the name of this
4590	// entity, and add the identifier to the list of results.
4591	addName(Name, ND: nullptr);
4592	}
4593
4594	void TypoCorrectionConsumer::addKeywordResult(StringRef Keyword) {
4595	// Compute the edit distance between the typo and this keyword,
4596	// and add the keyword to the list of results.
4597	addName(Name: Keyword, ND: nullptr, NNS: nullptr, isKeyword: true);
4598	}
4599
4600	void TypoCorrectionConsumer::addName(StringRef Name, NamedDecl *ND,
4601	NestedNameSpecifier *NNS, bool isKeyword) {
4602	// Use a simple length-based heuristic to determine the minimum possible
4603	// edit distance. If the minimum isn't good enough, bail out early.
4604	StringRef TypoStr = Typo->getName();
4605	unsigned MinED = abs(x: (int)Name.size() - (int)TypoStr.size());
4606	if (MinED && TypoStr.size() / MinED < 3)
4607	return;
4608
4609	// Compute an upper bound on the allowable edit distance, so that the
4610	// edit-distance algorithm can short-circuit.
4611	unsigned UpperBound = (TypoStr.size() + 2) / 3;
4612	unsigned ED = TypoStr.edit_distance(Other: Name, AllowReplacements: true, MaxEditDistance: UpperBound);
4613	if (ED > UpperBound) return;
4614
4615	TypoCorrection TC(&SemaRef.Context.Idents.get(Name), ND, NNS, ED);
4616	if (isKeyword) TC.makeKeyword();
4617	TC.setCorrectionRange(nullptr, Result.getLookupNameInfo());
4618	addCorrection(Correction: TC);
4619	}
4620
4621	static const unsigned MaxTypoDistanceResultSets = 5;
4622
4623	void TypoCorrectionConsumer::addCorrection(TypoCorrection Correction) {
4624	StringRef TypoStr = Typo->getName();
4625	StringRef Name = Correction.getCorrectionAsIdentifierInfo()->getName();
4626
4627	// For very short typos, ignore potential corrections that have a different
4628	// base identifier from the typo or which have a normalized edit distance
4629	// longer than the typo itself.
4630	if (TypoStr.size() < 3 &&
4631	(Name != TypoStr || Correction.getEditDistance(Normalized: true) > TypoStr.size()))
4632	return;
4633
4634	// If the correction is resolved but is not viable, ignore it.
4635	if (Correction.isResolved()) {
4636	checkCorrectionVisibility(SemaRef, TC&: Correction);
4637	if (!Correction || !isCandidateViable(CCC&: *CorrectionValidator, Candidate&: Correction))
4638	return;
4639	}
4640
4641	TypoResultList &CList =
4642	CorrectionResults[Correction.getEditDistance(Normalized: false)][Name];
4643
4644	if (!CList.empty() && !CList.back().isResolved())
4645	CList.pop_back();
4646	if (NamedDecl *NewND = Correction.getCorrectionDecl()) {
4647	auto RI = llvm::find_if(Range&: CList, P: [NewND](const TypoCorrection &TypoCorr) {
4648	return TypoCorr.getCorrectionDecl() == NewND;
4649	});
4650	if (RI != CList.end()) {
4651	// The Correction refers to a decl already in the list. No insertion is
4652	// necessary and all further cases will return.
4653
4654	auto IsDeprecated = [](Decl *D) {
4655	while (D) {
4656	if (D->isDeprecated())
4657	return true;
4658	D = llvm::dyn_cast_or_null<NamespaceDecl>(Val: D->getDeclContext());
4659	}
4660	return false;
4661	};
4662
4663	// Prefer non deprecated Corrections over deprecated and only then
4664	// sort using an alphabetical order.
4665	std::pair<bool, std::string> NewKey = {
4666	IsDeprecated(Correction.getFoundDecl()),
4667	Correction.getAsString(LO: SemaRef.getLangOpts())};
4668
4669	std::pair<bool, std::string> PrevKey = {
4670	IsDeprecated(RI->getFoundDecl()),
4671	RI->getAsString(LO: SemaRef.getLangOpts())};
4672
4673	if (NewKey < PrevKey)
4674	*RI = Correction;
4675	return;
4676	}
4677	}
4678	if (CList.empty() || Correction.isResolved())
4679	CList.push_back(Elt: Correction);
4680
4681	while (CorrectionResults.size() > MaxTypoDistanceResultSets)
4682	CorrectionResults.erase(position: std::prev(x: CorrectionResults.end()));
4683	}
4684
4685	void TypoCorrectionConsumer::addNamespaces(
4686	const llvm::MapVector<NamespaceDecl *, bool> &KnownNamespaces) {
4687	SearchNamespaces = true;
4688
4689	for (auto KNPair : KnownNamespaces)
4690	Namespaces.addNameSpecifier(KNPair.first);
4691
4692	bool SSIsTemplate = false;
4693	if (NestedNameSpecifier *NNS =
4694	(SS && SS->isValid()) ? SS->getScopeRep() : nullptr) {
4695	if (const Type *T = NNS->getAsType())
4696	SSIsTemplate = T->getTypeClass() == Type::TemplateSpecialization;
4697	}
4698	// Do not transform this into an iterator-based loop. The loop body can
4699	// trigger the creation of further types (through lazy deserialization) and
4700	// invalid iterators into this list.
4701	auto &Types = SemaRef.getASTContext().getTypes();
4702	for (unsigned I = 0; I != Types.size(); ++I) {
4703	const auto *TI = Types[I];
4704	if (CXXRecordDecl *CD = TI->getAsCXXRecordDecl()) {
4705	CD = CD->getCanonicalDecl();
4706	if (!CD->isDependentType() && !CD->isAnonymousStructOrUnion() &&
4707	!CD->isUnion() && CD->getIdentifier() &&
4708	(SSIsTemplate || !isa<ClassTemplateSpecializationDecl>(Val: CD)) &&
4709	(CD->isBeingDefined() || CD->isCompleteDefinition()))
4710	Namespaces.addNameSpecifier(CD);
4711	}
4712	}
4713	}
4714
4715	const TypoCorrection &TypoCorrectionConsumer::getNextCorrection() {
4716	if (++CurrentTCIndex < ValidatedCorrections.size())
4717	return ValidatedCorrections[CurrentTCIndex];
4718
4719	CurrentTCIndex = ValidatedCorrections.size();
4720	while (!CorrectionResults.empty()) {
4721	auto DI = CorrectionResults.begin();
4722	if (DI->second.empty()) {
4723	CorrectionResults.erase(position: DI);
4724	continue;
4725	}
4726
4727	auto RI = DI->second.begin();
4728	if (RI->second.empty()) {
4729	DI->second.erase(I: RI);
4730	performQualifiedLookups();
4731	continue;
4732	}
4733
4734	TypoCorrection TC = RI->second.pop_back_val();
4735	if (TC.isResolved() || TC.requiresImport() || resolveCorrection(Candidate&: TC)) {
4736	ValidatedCorrections.push_back(Elt: TC);
4737	return ValidatedCorrections[CurrentTCIndex];
4738	}
4739	}
4740	return ValidatedCorrections[0]; // The empty correction.
4741	}
4742
4743	bool TypoCorrectionConsumer::resolveCorrection(TypoCorrection &Candidate) {
4744	IdentifierInfo *Name = Candidate.getCorrectionAsIdentifierInfo();
4745	DeclContext *TempMemberContext = MemberContext;
4746	CXXScopeSpec *TempSS = SS.get();
4747	retry_lookup:
4748	LookupPotentialTypoResult(SemaRef, Result, Name, S, TempSS, TempMemberContext,
4749	EnteringContext,
4750	CorrectionValidator->IsObjCIvarLookup,
4751	Name == Typo && !Candidate.WillReplaceSpecifier());
4752	switch (Result.getResultKind()) {
4753	case LookupResult::NotFound:
4754	case LookupResult::NotFoundInCurrentInstantiation:
4755	case LookupResult::FoundUnresolvedValue:
4756	if (TempSS) {
4757	// Immediately retry the lookup without the given CXXScopeSpec
4758	TempSS = nullptr;
4759	Candidate.WillReplaceSpecifier(ForceReplacement: true);
4760	goto retry_lookup;
4761	}
4762	if (TempMemberContext) {
4763	if (SS && !TempSS)
4764	TempSS = SS.get();
4765	TempMemberContext = nullptr;
4766	goto retry_lookup;
4767	}
4768	if (SearchNamespaces)
4769	QualifiedResults.push_back(Elt: Candidate);
4770	break;
4771
4772	case LookupResult::Ambiguous:
4773	// We don't deal with ambiguities.
4774	break;
4775
4776	case LookupResult::Found:
4777	case LookupResult::FoundOverloaded:
4778	// Store all of the Decls for overloaded symbols
4779	for (auto *TRD : Result)
4780	Candidate.addCorrectionDecl(TRD);
4781	checkCorrectionVisibility(SemaRef, TC&: Candidate);
4782	if (!isCandidateViable(CCC&: *CorrectionValidator, Candidate)) {
4783	if (SearchNamespaces)
4784	QualifiedResults.push_back(Elt: Candidate);
4785	break;
4786	}
4787	Candidate.setCorrectionRange(SS.get(), Result.getLookupNameInfo());
4788	return true;
4789	}
4790	return false;
4791	}
4792
4793	void TypoCorrectionConsumer::performQualifiedLookups() {
4794	unsigned TypoLen = Typo->getName().size();
4795	for (const TypoCorrection &QR : QualifiedResults) {
4796	for (const auto &NSI : Namespaces) {
4797	DeclContext *Ctx = NSI.DeclCtx;
4798	const Type *NSType = NSI.NameSpecifier->getAsType();
4799
4800	// If the current NestedNameSpecifier refers to a class and the
4801	// current correction candidate is the name of that class, then skip
4802	// it as it is unlikely a qualified version of the class' constructor
4803	// is an appropriate correction.
4804	if (CXXRecordDecl *NSDecl = NSType ? NSType->getAsCXXRecordDecl() :
4805	nullptr) {
4806	if (NSDecl->getIdentifier() == QR.getCorrectionAsIdentifierInfo())
4807	continue;
4808	}
4809
4810	TypoCorrection TC(QR);
4811	TC.ClearCorrectionDecls();
4812	TC.setCorrectionSpecifier(NSI.NameSpecifier);
4813	TC.setQualifierDistance(NSI.EditDistance);
4814	TC.setCallbackDistance(0); // Reset the callback distance
4815
4816	// If the current correction candidate and namespace combination are
4817	// too far away from the original typo based on the normalized edit
4818	// distance, then skip performing a qualified name lookup.
4819	unsigned TmpED = TC.getEditDistance(Normalized: true);
4820	if (QR.getCorrectionAsIdentifierInfo() != Typo && TmpED &&
4821	TypoLen / TmpED < 3)
4822	continue;
4823
4824	Result.clear();
4825	Result.setLookupName(QR.getCorrectionAsIdentifierInfo());
4826	if (!SemaRef.LookupQualifiedName(Result, Ctx))
4827	continue;
4828
4829	// Any corrections added below will be validated in subsequent
4830	// iterations of the main while() loop over the Consumer's contents.
4831	switch (Result.getResultKind()) {
4832	case LookupResult::Found:
4833	case LookupResult::FoundOverloaded: {
4834	if (SS && SS->isValid()) {
4835	std::string NewQualified = TC.getAsString(LO: SemaRef.getLangOpts());
4836	std::string OldQualified;
4837	llvm::raw_string_ostream OldOStream(OldQualified);
4838	SS->getScopeRep()->print(OS&: OldOStream, Policy: SemaRef.getPrintingPolicy());
4839	OldOStream << Typo->getName();
4840	// If correction candidate would be an identical written qualified
4841	// identifier, then the existing CXXScopeSpec probably included a
4842	// typedef that didn't get accounted for properly.
4843	if (OldOStream.str() == NewQualified)
4844	break;
4845	}
4846	for (LookupResult::iterator TRD = Result.begin(), TRDEnd = Result.end();
4847	TRD != TRDEnd; ++TRD) {
4848	if (SemaRef.CheckMemberAccess(UseLoc: TC.getCorrectionRange().getBegin(),
4849	NamingClass: NSType ? NSType->getAsCXXRecordDecl()
4850	: nullptr,
4851	Found: TRD.getPair()) == Sema::AR_accessible)
4852	TC.addCorrectionDecl(CDecl: *TRD);
4853	}
4854	if (TC.isResolved()) {
4855	TC.setCorrectionRange(SS.get(), Result.getLookupNameInfo());
4856	addCorrection(Correction: TC);
4857	}
4858	break;
4859	}
4860	case LookupResult::NotFound:
4861	case LookupResult::NotFoundInCurrentInstantiation:
4862	case LookupResult::Ambiguous:
4863	case LookupResult::FoundUnresolvedValue:
4864	break;
4865	}
4866	}
4867	}
4868	QualifiedResults.clear();
4869	}
4870
4871	TypoCorrectionConsumer::NamespaceSpecifierSet::NamespaceSpecifierSet(
4872	ASTContext &Context, DeclContext *CurContext, CXXScopeSpec *CurScopeSpec)
4873	: Context(Context), CurContextChain(buildContextChain(Start: CurContext)) {
4874	if (NestedNameSpecifier *NNS =
4875	CurScopeSpec ? CurScopeSpec->getScopeRep() : nullptr) {
4876	llvm::raw_string_ostream SpecifierOStream(CurNameSpecifier);
4877	NNS->print(OS&: SpecifierOStream, Policy: Context.getPrintingPolicy());
4878
4879	getNestedNameSpecifierIdentifiers(NNS, Identifiers&: CurNameSpecifierIdentifiers);
4880	}
4881	// Build the list of identifiers that would be used for an absolute
4882	// (from the global context) NestedNameSpecifier referring to the current
4883	// context.
4884	for (DeclContext *C : llvm::reverse(C&: CurContextChain)) {
4885	if (auto *ND = dyn_cast_or_null<NamespaceDecl>(Val: C))
4886	CurContextIdentifiers.push_back(Elt: ND->getIdentifier());
4887	}
4888
4889	// Add the global context as a NestedNameSpecifier
4890	SpecifierInfo SI = {.DeclCtx: cast<DeclContext>(Val: Context.getTranslationUnitDecl()),
4891	.NameSpecifier: NestedNameSpecifier::GlobalSpecifier(Context), .EditDistance: 1};
4892	DistanceMap[1].push_back(Elt: SI);
4893	}
4894
4895	auto TypoCorrectionConsumer::NamespaceSpecifierSet::buildContextChain(
4896	DeclContext *Start) -> DeclContextList {
4897	assert(Start && "Building a context chain from a null context");
4898	DeclContextList Chain;
4899	for (DeclContext *DC = Start->getPrimaryContext(); DC != nullptr;
4900	DC = DC->getLookupParent()) {
4901	NamespaceDecl *ND = dyn_cast_or_null<NamespaceDecl>(Val: DC);
4902	if (!DC->isInlineNamespace() && !DC->isTransparentContext() &&
4903	!(ND && ND->isAnonymousNamespace()))
4904	Chain.push_back(Elt: DC->getPrimaryContext());
4905	}
4906	return Chain;
4907	}
4908
4909	unsigned
4910	TypoCorrectionConsumer::NamespaceSpecifierSet::buildNestedNameSpecifier(
4911	DeclContextList &DeclChain, NestedNameSpecifier *&NNS) {
4912	unsigned NumSpecifiers = 0;
4913	for (DeclContext *C : llvm::reverse(C&: DeclChain)) {
4914	if (auto *ND = dyn_cast_or_null<NamespaceDecl>(Val: C)) {
4915	NNS = NestedNameSpecifier::Create(Context, Prefix: NNS, NS: ND);
4916	++NumSpecifiers;
4917	} else if (auto *RD = dyn_cast_or_null<RecordDecl>(Val: C)) {
4918	NNS = NestedNameSpecifier::Create(Context, NNS, RD->isTemplateDecl(),
4919	RD->getTypeForDecl());
4920	++NumSpecifiers;
4921	}
4922	}
4923	return NumSpecifiers;
4924	}
4925
4926	void TypoCorrectionConsumer::NamespaceSpecifierSet::addNameSpecifier(
4927	DeclContext *Ctx) {
4928	NestedNameSpecifier *NNS = nullptr;
4929	unsigned NumSpecifiers = 0;
4930	DeclContextList NamespaceDeclChain(buildContextChain(Start: Ctx));
4931	DeclContextList FullNamespaceDeclChain(NamespaceDeclChain);
4932
4933	// Eliminate common elements from the two DeclContext chains.
4934	for (DeclContext *C : llvm::reverse(C&: CurContextChain)) {
4935	if (NamespaceDeclChain.empty() || NamespaceDeclChain.back() != C)
4936	break;
4937	NamespaceDeclChain.pop_back();
4938	}
4939
4940	// Build the NestedNameSpecifier from what is left of the NamespaceDeclChain
4941	NumSpecifiers = buildNestedNameSpecifier(DeclChain&: NamespaceDeclChain, NNS);
4942
4943	// Add an explicit leading '::' specifier if needed.
4944	if (NamespaceDeclChain.empty()) {
4945	// Rebuild the NestedNameSpecifier as a globally-qualified specifier.
4946	NNS = NestedNameSpecifier::GlobalSpecifier(Context);
4947	NumSpecifiers =
4948	buildNestedNameSpecifier(DeclChain&: FullNamespaceDeclChain, NNS);
4949	} else if (NamedDecl *ND =
4950	dyn_cast_or_null<NamedDecl>(Val: NamespaceDeclChain.back())) {
4951	IdentifierInfo *Name = ND->getIdentifier();
4952	bool SameNameSpecifier = false;
4953	if (llvm::is_contained(Range&: CurNameSpecifierIdentifiers, Element: Name)) {
4954	std::string NewNameSpecifier;
4955	llvm::raw_string_ostream SpecifierOStream(NewNameSpecifier);
4956	SmallVector<const IdentifierInfo *, 4> NewNameSpecifierIdentifiers;
4957	getNestedNameSpecifierIdentifiers(NNS, Identifiers&: NewNameSpecifierIdentifiers);
4958	NNS->print(OS&: SpecifierOStream, Policy: Context.getPrintingPolicy());
4959	SpecifierOStream.flush();
4960	SameNameSpecifier = NewNameSpecifier == CurNameSpecifier;
4961	}
4962	if (SameNameSpecifier || llvm::is_contained(Range&: CurContextIdentifiers, Element: Name)) {
4963	// Rebuild the NestedNameSpecifier as a globally-qualified specifier.
4964	NNS = NestedNameSpecifier::GlobalSpecifier(Context);
4965	NumSpecifiers =
4966	buildNestedNameSpecifier(DeclChain&: FullNamespaceDeclChain, NNS);
4967	}
4968	}
4969
4970	// If the built NestedNameSpecifier would be replacing an existing
4971	// NestedNameSpecifier, use the number of component identifiers that
4972	// would need to be changed as the edit distance instead of the number
4973	// of components in the built NestedNameSpecifier.
4974	if (NNS && !CurNameSpecifierIdentifiers.empty()) {
4975	SmallVector<const IdentifierInfo*, 4> NewNameSpecifierIdentifiers;
4976	getNestedNameSpecifierIdentifiers(NNS, Identifiers&: NewNameSpecifierIdentifiers);
4977	NumSpecifiers =
4978	llvm::ComputeEditDistance(FromArray: llvm::ArrayRef(CurNameSpecifierIdentifiers),
4979	ToArray: llvm::ArrayRef(NewNameSpecifierIdentifiers));
4980	}
4981
4982	SpecifierInfo SI = {.DeclCtx: Ctx, .NameSpecifier: NNS, .EditDistance: NumSpecifiers};
4983	DistanceMap[NumSpecifiers].push_back(Elt: SI);
4984	}
4985
4986	/// Perform name lookup for a possible result for typo correction.
4987	static void LookupPotentialTypoResult(Sema &SemaRef,
4988	LookupResult &Res,
4989	IdentifierInfo *Name,
4990	Scope *S, CXXScopeSpec *SS,
4991	DeclContext *MemberContext,
4992	bool EnteringContext,
4993	bool isObjCIvarLookup,
4994	bool FindHidden) {
4995	Res.suppressDiagnostics();
4996	Res.clear();
4997	Res.setLookupName(Name);
4998	Res.setAllowHidden(FindHidden);
4999	if (MemberContext) {
5000	if (ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(Val: MemberContext)) {
5001	if (isObjCIvarLookup) {
5002	if (ObjCIvarDecl *Ivar = Class->lookupInstanceVariable(IVarName: Name)) {
5003	Res.addDecl(Ivar);
5004	Res.resolveKind();
5005	return;
5006	}
5007	}
5008
5009	if (ObjCPropertyDecl *Prop = Class->FindPropertyDeclaration(
5010	Name, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
5011	Res.addDecl(Prop);
5012	Res.resolveKind();
5013	return;
5014	}
5015	}
5016
5017	SemaRef.LookupQualifiedName(R&: Res, LookupCtx: MemberContext);
5018	return;
5019	}
5020
5021	SemaRef.LookupParsedName(R&: Res, S, SS, /*AllowBuiltinCreation=*/false,
5022	EnteringContext);
5023
5024	// Fake ivar lookup; this should really be part of
5025	// LookupParsedName.
5026	if (ObjCMethodDecl *Method = SemaRef.getCurMethodDecl()) {
5027	if (Method->isInstanceMethod() && Method->getClassInterface() &&
5028	(Res.empty() ||
5029	(Res.isSingleResult() &&
5030	Res.getFoundDecl()->isDefinedOutsideFunctionOrMethod()))) {
5031	if (ObjCIvarDecl *IV
5032	= Method->getClassInterface()->lookupInstanceVariable(IVarName: Name)) {
5033	Res.addDecl(IV);
5034	Res.resolveKind();
5035	}
5036	}
5037	}
5038	}
5039
5040	/// Add keywords to the consumer as possible typo corrections.
5041	static void AddKeywordsToConsumer(Sema &SemaRef,
5042	TypoCorrectionConsumer &Consumer,
5043	Scope *S, CorrectionCandidateCallback &CCC,
5044	bool AfterNestedNameSpecifier) {
5045	if (AfterNestedNameSpecifier) {
5046	// For 'X::', we know exactly which keywords can appear next.
5047	Consumer.addKeywordResult(Keyword: "template");
5048	if (CCC.WantExpressionKeywords)
5049	Consumer.addKeywordResult(Keyword: "operator");
5050	return;
5051	}
5052
5053	if (CCC.WantObjCSuper)
5054	Consumer.addKeywordResult(Keyword: "super");
5055
5056	if (CCC.WantTypeSpecifiers) {
5057	// Add type-specifier keywords to the set of results.
5058	static const char *const CTypeSpecs[] = {
5059	"char", "const", "double", "enum", "float", "int", "long", "short",
5060	"signed", "struct", "union", "unsigned", "void", "volatile",
5061	"_Complex", "_Imaginary",
5062	// storage-specifiers as well
5063	"extern", "inline", "static", "typedef"
5064	};
5065
5066	for (const auto *CTS : CTypeSpecs)
5067	Consumer.addKeywordResult(Keyword: CTS);
5068
5069	if (SemaRef.getLangOpts().C99)
5070	Consumer.addKeywordResult(Keyword: "restrict");
5071	if (SemaRef.getLangOpts().Bool || SemaRef.getLangOpts().CPlusPlus)
5072	Consumer.addKeywordResult(Keyword: "bool");
5073	else if (SemaRef.getLangOpts().C99)
5074	Consumer.addKeywordResult(Keyword: "_Bool");
5075
5076	if (SemaRef.getLangOpts().CPlusPlus) {
5077	Consumer.addKeywordResult(Keyword: "class");
5078	Consumer.addKeywordResult(Keyword: "typename");
5079	Consumer.addKeywordResult(Keyword: "wchar_t");
5080
5081	if (SemaRef.getLangOpts().CPlusPlus11) {
5082	Consumer.addKeywordResult(Keyword: "char16_t");
5083	Consumer.addKeywordResult(Keyword: "char32_t");
5084	Consumer.addKeywordResult(Keyword: "constexpr");
5085	Consumer.addKeywordResult(Keyword: "decltype");
5086	Consumer.addKeywordResult(Keyword: "thread_local");
5087	}
5088	}
5089
5090	if (SemaRef.getLangOpts().GNUKeywords)
5091	Consumer.addKeywordResult(Keyword: "typeof");
5092	} else if (CCC.WantFunctionLikeCasts) {
5093	static const char *const CastableTypeSpecs[] = {
5094	"char", "double", "float", "int", "long", "short",
5095	"signed", "unsigned", "void"
5096	};
5097	for (auto *kw : CastableTypeSpecs)
5098	Consumer.addKeywordResult(Keyword: kw);
5099	}
5100
5101	if (CCC.WantCXXNamedCasts && SemaRef.getLangOpts().CPlusPlus) {
5102	Consumer.addKeywordResult(Keyword: "const_cast");
5103	Consumer.addKeywordResult(Keyword: "dynamic_cast");
5104	Consumer.addKeywordResult(Keyword: "reinterpret_cast");
5105	Consumer.addKeywordResult(Keyword: "static_cast");
5106	}
5107
5108	if (CCC.WantExpressionKeywords) {
5109	Consumer.addKeywordResult(Keyword: "sizeof");
5110	if (SemaRef.getLangOpts().Bool || SemaRef.getLangOpts().CPlusPlus) {
5111	Consumer.addKeywordResult(Keyword: "false");
5112	Consumer.addKeywordResult(Keyword: "true");
5113	}
5114
5115	if (SemaRef.getLangOpts().CPlusPlus) {
5116	static const char *const CXXExprs[] = {
5117	"delete", "new", "operator", "throw", "typeid"
5118	};
5119	for (const auto *CE : CXXExprs)
5120	Consumer.addKeywordResult(Keyword: CE);
5121
5122	if (isa<CXXMethodDecl>(Val: SemaRef.CurContext) &&
5123	cast<CXXMethodDecl>(Val: SemaRef.CurContext)->isInstance())
5124	Consumer.addKeywordResult(Keyword: "this");
5125
5126	if (SemaRef.getLangOpts().CPlusPlus11) {
5127	Consumer.addKeywordResult(Keyword: "alignof");
5128	Consumer.addKeywordResult(Keyword: "nullptr");
5129	}
5130	}
5131
5132	if (SemaRef.getLangOpts().C11) {
5133	// FIXME: We should not suggest _Alignof if the alignof macro
5134	// is present.
5135	Consumer.addKeywordResult(Keyword: "_Alignof");
5136	}
5137	}
5138
5139	if (CCC.WantRemainingKeywords) {
5140	if (SemaRef.getCurFunctionOrMethodDecl() || SemaRef.getCurBlock()) {
5141	// Statements.
5142	static const char *const CStmts[] = {
5143	"do", "else", "for", "goto", "if", "return", "switch", "while" };
5144	for (const auto *CS : CStmts)
5145	Consumer.addKeywordResult(Keyword: CS);
5146
5147	if (SemaRef.getLangOpts().CPlusPlus) {
5148	Consumer.addKeywordResult(Keyword: "catch");
5149	Consumer.addKeywordResult(Keyword: "try");
5150	}
5151
5152	if (S && S->getBreakParent())
5153	Consumer.addKeywordResult(Keyword: "break");
5154
5155	if (S && S->getContinueParent())
5156	Consumer.addKeywordResult(Keyword: "continue");
5157
5158	if (SemaRef.getCurFunction() &&
5159	!SemaRef.getCurFunction()->SwitchStack.empty()) {
5160	Consumer.addKeywordResult(Keyword: "case");
5161	Consumer.addKeywordResult(Keyword: "default");
5162	}
5163	} else {
5164	if (SemaRef.getLangOpts().CPlusPlus) {
5165	Consumer.addKeywordResult(Keyword: "namespace");
5166	Consumer.addKeywordResult(Keyword: "template");
5167	}
5168
5169	if (S && S->isClassScope()) {
5170	Consumer.addKeywordResult(Keyword: "explicit");
5171	Consumer.addKeywordResult(Keyword: "friend");
5172	Consumer.addKeywordResult(Keyword: "mutable");
5173	Consumer.addKeywordResult(Keyword: "private");
5174	Consumer.addKeywordResult(Keyword: "protected");
5175	Consumer.addKeywordResult(Keyword: "public");
5176	Consumer.addKeywordResult(Keyword: "virtual");
5177	}
5178	}
5179
5180	if (SemaRef.getLangOpts().CPlusPlus) {
5181	Consumer.addKeywordResult(Keyword: "using");
5182
5183	if (SemaRef.getLangOpts().CPlusPlus11)
5184	Consumer.addKeywordResult(Keyword: "static_assert");
5185	}
5186	}
5187	}
5188
5189	std::unique_ptr<TypoCorrectionConsumer> Sema::makeTypoCorrectionConsumer(
5190	const DeclarationNameInfo &TypoName, Sema::LookupNameKind LookupKind,
5191	Scope *S, CXXScopeSpec *SS, CorrectionCandidateCallback &CCC,
5192	DeclContext *MemberContext, bool EnteringContext,
5193	const ObjCObjectPointerType *OPT, bool ErrorRecovery) {
5194
5195	if (Diags.hasFatalErrorOccurred() || !getLangOpts().SpellChecking ||
5196	DisableTypoCorrection)
5197	return nullptr;
5198
5199	// In Microsoft mode, don't perform typo correction in a template member
5200	// function dependent context because it interferes with the "lookup into
5201	// dependent bases of class templates" feature.
5202	if (getLangOpts().MSVCCompat && CurContext->isDependentContext() &&
5203	isa<CXXMethodDecl>(Val: CurContext))
5204	return nullptr;
5205
5206	// We only attempt to correct typos for identifiers.
5207	IdentifierInfo *Typo = TypoName.getName().getAsIdentifierInfo();
5208	if (!Typo)
5209	return nullptr;
5210
5211	// If the scope specifier itself was invalid, don't try to correct
5212	// typos.
5213	if (SS && SS->isInvalid())
5214	return nullptr;
5215
5216	// Never try to correct typos during any kind of code synthesis.
5217	if (!CodeSynthesisContexts.empty())
5218	return nullptr;
5219
5220	// Don't try to correct 'super'.
5221	if (S && S->isInObjcMethodScope() && Typo == getSuperIdentifier())
5222	return nullptr;
5223
5224	// Abort if typo correction already failed for this specific typo.
5225	IdentifierSourceLocations::iterator locs = TypoCorrectionFailures.find(Val: Typo);
5226	if (locs != TypoCorrectionFailures.end() &&
5227	locs->second.count(V: TypoName.getLoc()))
5228	return nullptr;
5229
5230	// Don't try to correct the identifier "vector" when in AltiVec mode.
5231	// TODO: Figure out why typo correction misbehaves in this case, fix it, and
5232	// remove this workaround.
5233	if ((getLangOpts().AltiVec || getLangOpts().ZVector) && Typo->isStr(Str: "vector"))
5234	return nullptr;
5235
5236	// Provide a stop gap for files that are just seriously broken. Trying
5237	// to correct all typos can turn into a HUGE performance penalty, causing
5238	// some files to take minutes to get rejected by the parser.
5239	unsigned Limit = getDiagnostics().getDiagnosticOptions().SpellCheckingLimit;
5240	if (Limit && TyposCorrected >= Limit)
5241	return nullptr;
5242	++TyposCorrected;
5243
5244	// If we're handling a missing symbol error, using modules, and the
5245	// special search all modules option is used, look for a missing import.
5246	if (ErrorRecovery && getLangOpts().Modules &&
5247	getLangOpts().ModulesSearchAll) {
5248	// The following has the side effect of loading the missing module.
5249	getModuleLoader().lookupMissingImports(Name: Typo->getName(),
5250	TriggerLoc: TypoName.getBeginLoc());
5251	}
5252
5253	// Extend the lifetime of the callback. We delayed this until here
5254	// to avoid allocations in the hot path (which is where no typo correction
5255	// occurs). Note that CorrectionCandidateCallback is polymorphic and
5256	// initially stack-allocated.
5257	std::unique_ptr<CorrectionCandidateCallback> ClonedCCC = CCC.clone();
5258	auto Consumer = std::make_unique<TypoCorrectionConsumer>(
5259	args&: *this, args: TypoName, args&: LookupKind, args&: S, args&: SS, args: std::move(ClonedCCC), args&: MemberContext,
5260	args&: EnteringContext);
5261
5262	// Perform name lookup to find visible, similarly-named entities.
5263	bool IsUnqualifiedLookup = false;
5264	DeclContext *QualifiedDC = MemberContext;
5265	if (MemberContext) {
5266	LookupVisibleDecls(MemberContext, LookupKind, *Consumer);
5267
5268	// Look in qualified interfaces.
5269	if (OPT) {
5270	for (auto *I : OPT->quals())
5271	LookupVisibleDecls(I, LookupKind, *Consumer);
5272	}
5273	} else if (SS && SS->isSet()) {
5274	QualifiedDC = computeDeclContext(SS: *SS, EnteringContext);
5275	if (!QualifiedDC)
5276	return nullptr;
5277
5278	LookupVisibleDecls(QualifiedDC, LookupKind, *Consumer);
5279	} else {
5280	IsUnqualifiedLookup = true;
5281	}
5282
5283	// Determine whether we are going to search in the various namespaces for
5284	// corrections.
5285	bool SearchNamespaces
5286	= getLangOpts().CPlusPlus &&
5287	(IsUnqualifiedLookup || (SS && SS->isSet()));
5288
5289	if (IsUnqualifiedLookup || SearchNamespaces) {
5290	// For unqualified lookup, look through all of the names that we have
5291	// seen in this translation unit.
5292	// FIXME: Re-add the ability to skip very unlikely potential corrections.
5293	for (const auto &I : Context.Idents)
5294	Consumer->FoundName(I.getKey());
5295
5296	// Walk through identifiers in external identifier sources.
5297	// FIXME: Re-add the ability to skip very unlikely potential corrections.
5298	if (IdentifierInfoLookup *External
5299	= Context.Idents.getExternalIdentifierLookup()) {
5300	std::unique_ptr<IdentifierIterator> Iter(External->getIdentifiers());
5301	do {
5302	StringRef Name = Iter->Next();
5303	if (Name.empty())
5304	break;
5305
5306	Consumer->FoundName(Name);
5307	} while (true);
5308	}
5309	}
5310
5311	AddKeywordsToConsumer(SemaRef&: *this, Consumer&: *Consumer, S,
5312	CCC&: *Consumer->getCorrectionValidator(),
5313	AfterNestedNameSpecifier: SS && SS->isNotEmpty());
5314
5315	// Build the NestedNameSpecifiers for the KnownNamespaces, if we're going
5316	// to search those namespaces.
5317	if (SearchNamespaces) {
5318	// Load any externally-known namespaces.
5319	if (ExternalSource && !LoadedExternalKnownNamespaces) {
5320	SmallVector<NamespaceDecl *, 4> ExternalKnownNamespaces;
5321	LoadedExternalKnownNamespaces = true;
5322	ExternalSource->ReadKnownNamespaces(Namespaces&: ExternalKnownNamespaces);
5323	for (auto *N : ExternalKnownNamespaces)
5324	KnownNamespaces[N] = true;
5325	}
5326
5327	Consumer->addNamespaces(KnownNamespaces);
5328	}
5329
5330	return Consumer;
5331	}
5332
5333	/// Try to "correct" a typo in the source code by finding
5334	/// visible declarations whose names are similar to the name that was
5335	/// present in the source code.
5336	///
5337	/// \param TypoName the \c DeclarationNameInfo structure that contains
5338	/// the name that was present in the source code along with its location.
5339	///
5340	/// \param LookupKind the name-lookup criteria used to search for the name.
5341	///
5342	/// \param S the scope in which name lookup occurs.
5343	///
5344	/// \param SS the nested-name-specifier that precedes the name we're
5345	/// looking for, if present.
5346	///
5347	/// \param CCC A CorrectionCandidateCallback object that provides further
5348	/// validation of typo correction candidates. It also provides flags for
5349	/// determining the set of keywords permitted.
5350	///
5351	/// \param MemberContext if non-NULL, the context in which to look for
5352	/// a member access expression.
5353	///
5354	/// \param EnteringContext whether we're entering the context described by
5355	/// the nested-name-specifier SS.
5356	///
5357	/// \param OPT when non-NULL, the search for visible declarations will
5358	/// also walk the protocols in the qualified interfaces of \p OPT.
5359	///
5360	/// \returns a \c TypoCorrection containing the corrected name if the typo
5361	/// along with information such as the \c NamedDecl where the corrected name
5362	/// was declared, and any additional \c NestedNameSpecifier needed to access
5363	/// it (C++ only). The \c TypoCorrection is empty if there is no correction.
5364	TypoCorrection Sema::CorrectTypo(const DeclarationNameInfo &TypoName,
5365	Sema::LookupNameKind LookupKind,
5366	Scope *S, CXXScopeSpec *SS,
5367	CorrectionCandidateCallback &CCC,
5368	CorrectTypoKind Mode,
5369	DeclContext *MemberContext,
5370	bool EnteringContext,
5371	const ObjCObjectPointerType *OPT,
5372	bool RecordFailure) {
5373	// Always let the ExternalSource have the first chance at correction, even
5374	// if we would otherwise have given up.
5375	if (ExternalSource) {
5376	if (TypoCorrection Correction =
5377	ExternalSource->CorrectTypo(Typo: TypoName, LookupKind, S, SS, CCC,
5378	MemberContext, EnteringContext, OPT))
5379	return Correction;
5380	}
5381
5382	// Ugly hack equivalent to CTC == CTC_ObjCMessageReceiver;
5383	// WantObjCSuper is only true for CTC_ObjCMessageReceiver and for
5384	// some instances of CTC_Unknown, while WantRemainingKeywords is true
5385	// for CTC_Unknown but not for CTC_ObjCMessageReceiver.
5386	bool ObjCMessageReceiver = CCC.WantObjCSuper && !CCC.WantRemainingKeywords;
5387
5388	IdentifierInfo *Typo = TypoName.getName().getAsIdentifierInfo();
5389	auto Consumer = makeTypoCorrectionConsumer(TypoName, LookupKind, S, SS, CCC,
5390	MemberContext, EnteringContext,
5391	OPT, ErrorRecovery: Mode == CTK_ErrorRecovery);
5392
5393	if (!Consumer)
5394	return TypoCorrection();
5395
5396	// If we haven't found anything, we're done.
5397	if (Consumer->empty())
5398	return FailedCorrection(Typo, TypoLoc: TypoName.getLoc(), RecordFailure);
5399
5400	// Make sure the best edit distance (prior to adding any namespace qualifiers)
5401	// is not more that about a third of the length of the typo's identifier.
5402	unsigned ED = Consumer->getBestEditDistance(Normalized: true);
5403	unsigned TypoLen = Typo->getName().size();
5404	if (ED > 0 && TypoLen / ED < 3)
5405	return FailedCorrection(Typo, TypoLoc: TypoName.getLoc(), RecordFailure);
5406
5407	TypoCorrection BestTC = Consumer->getNextCorrection();
5408	TypoCorrection SecondBestTC = Consumer->getNextCorrection();
5409	if (!BestTC)
5410	return FailedCorrection(Typo, TypoLoc: TypoName.getLoc(), RecordFailure);
5411
5412	ED = BestTC.getEditDistance();
5413
5414	if (TypoLen >= 3 && ED > 0 && TypoLen / ED < 3) {
5415	// If this was an unqualified lookup and we believe the callback
5416	// object wouldn't have filtered out possible corrections, note
5417	// that no correction was found.
5418	return FailedCorrection(Typo, TypoLoc: TypoName.getLoc(), RecordFailure);
5419	}
5420
5421	// If only a single name remains, return that result.
5422	if (!SecondBestTC ||
5423	SecondBestTC.getEditDistance(Normalized: false) > BestTC.getEditDistance(Normalized: false)) {
5424	const TypoCorrection &Result = BestTC;
5425
5426	// Don't correct to a keyword that's the same as the typo; the keyword
5427	// wasn't actually in scope.
5428	if (ED == 0 && Result.isKeyword())
5429	return FailedCorrection(Typo, TypoLoc: TypoName.getLoc(), RecordFailure);
5430
5431	TypoCorrection TC = Result;
5432	TC.setCorrectionRange(SS, TypoName);
5433	checkCorrectionVisibility(SemaRef&: *this, TC);
5434	return TC;
5435	} else if (SecondBestTC && ObjCMessageReceiver) {
5436	// Prefer 'super' when we're completing in a message-receiver
5437	// context.
5438
5439	if (BestTC.getCorrection().getAsString() != "super") {
5440	if (SecondBestTC.getCorrection().getAsString() == "super")
5441	BestTC = SecondBestTC;
5442	else if ((*Consumer)["super"].front().isKeyword())
5443	BestTC = (*Consumer)["super"].front();
5444	}
5445	// Don't correct to a keyword that's the same as the typo; the keyword
5446	// wasn't actually in scope.
5447	if (BestTC.getEditDistance() == 0 ||
5448	BestTC.getCorrection().getAsString() != "super")
5449	return FailedCorrection(Typo, TypoLoc: TypoName.getLoc(), RecordFailure);
5450
5451	BestTC.setCorrectionRange(SS, TypoName);
5452	return BestTC;
5453	}
5454
5455	// Record the failure's location if needed and return an empty correction. If
5456	// this was an unqualified lookup and we believe the callback object did not
5457	// filter out possible corrections, also cache the failure for the typo.
5458	return FailedCorrection(Typo, TypoLoc: TypoName.getLoc(), RecordFailure: RecordFailure && !SecondBestTC);
5459	}
5460
5461	/// Try to "correct" a typo in the source code by finding
5462	/// visible declarations whose names are similar to the name that was
5463	/// present in the source code.
5464	///
5465	/// \param TypoName the \c DeclarationNameInfo structure that contains
5466	/// the name that was present in the source code along with its location.
5467	///
5468	/// \param LookupKind the name-lookup criteria used to search for the name.
5469	///
5470	/// \param S the scope in which name lookup occurs.
5471	///
5472	/// \param SS the nested-name-specifier that precedes the name we're
5473	/// looking for, if present.
5474	///
5475	/// \param CCC A CorrectionCandidateCallback object that provides further
5476	/// validation of typo correction candidates. It also provides flags for
5477	/// determining the set of keywords permitted.
5478	///
5479	/// \param TDG A TypoDiagnosticGenerator functor that will be used to print
5480	/// diagnostics when the actual typo correction is attempted.
5481	///
5482	/// \param TRC A TypoRecoveryCallback functor that will be used to build an
5483	/// Expr from a typo correction candidate.
5484	///
5485	/// \param MemberContext if non-NULL, the context in which to look for
5486	/// a member access expression.
5487	///
5488	/// \param EnteringContext whether we're entering the context described by
5489	/// the nested-name-specifier SS.
5490	///
5491	/// \param OPT when non-NULL, the search for visible declarations will
5492	/// also walk the protocols in the qualified interfaces of \p OPT.
5493	///
5494	/// \returns a new \c TypoExpr that will later be replaced in the AST with an
5495	/// Expr representing the result of performing typo correction, or nullptr if
5496	/// typo correction is not possible. If nullptr is returned, no diagnostics will
5497	/// be emitted and it is the responsibility of the caller to emit any that are
5498	/// needed.
5499	TypoExpr *Sema::CorrectTypoDelayed(
5500	const DeclarationNameInfo &TypoName, Sema::LookupNameKind LookupKind,
5501	Scope *S, CXXScopeSpec *SS, CorrectionCandidateCallback &CCC,
5502	TypoDiagnosticGenerator TDG, TypoRecoveryCallback TRC, CorrectTypoKind Mode,
5503	DeclContext *MemberContext, bool EnteringContext,
5504	const ObjCObjectPointerType *OPT) {
5505	auto Consumer = makeTypoCorrectionConsumer(TypoName, LookupKind, S, SS, CCC,
5506	MemberContext, EnteringContext,
5507	OPT, ErrorRecovery: Mode == CTK_ErrorRecovery);
5508
5509	// Give the external sema source a chance to correct the typo.
5510	TypoCorrection ExternalTypo;
5511	if (ExternalSource && Consumer) {
5512	ExternalTypo = ExternalSource->CorrectTypo(
5513	Typo: TypoName, LookupKind, S, SS, CCC&: *Consumer->getCorrectionValidator(),
5514	MemberContext, EnteringContext, OPT);
5515	if (ExternalTypo)
5516	Consumer->addCorrection(Correction: ExternalTypo);
5517	}
5518
5519	if (!Consumer || Consumer->empty())
5520	return nullptr;
5521
5522	// Make sure the best edit distance (prior to adding any namespace qualifiers)
5523	// is not more that about a third of the length of the typo's identifier.
5524	unsigned ED = Consumer->getBestEditDistance(Normalized: true);
5525	IdentifierInfo *Typo = TypoName.getName().getAsIdentifierInfo();
5526	if (!ExternalTypo && ED > 0 && Typo->getName().size() / ED < 3)
5527	return nullptr;
5528	ExprEvalContexts.back().NumTypos++;
5529	return createDelayedTypo(TCC: std::move(Consumer), TDG: std::move(TDG), TRC: std::move(TRC),
5530	TypoLoc: TypoName.getLoc());
5531	}
5532
5533	void TypoCorrection::addCorrectionDecl(NamedDecl *CDecl) {
5534	if (!CDecl) return;
5535
5536	if (isKeyword())
5537	CorrectionDecls.clear();
5538
5539	CorrectionDecls.push_back(Elt: CDecl);
5540
5541	if (!CorrectionName)
5542	CorrectionName = CDecl->getDeclName();
5543	}
5544
5545	std::string TypoCorrection::getAsString(const LangOptions &LO) const {
5546	if (CorrectionNameSpec) {
5547	std::string tmpBuffer;
5548	llvm::raw_string_ostream PrefixOStream(tmpBuffer);
5549	CorrectionNameSpec->print(OS&: PrefixOStream, Policy: PrintingPolicy(LO));
5550	PrefixOStream << CorrectionName;
5551	return PrefixOStream.str();
5552	}
5553
5554	return CorrectionName.getAsString();
5555	}
5556
5557	bool CorrectionCandidateCallback::ValidateCandidate(
5558	const TypoCorrection &candidate) {
5559	if (!candidate.isResolved())
5560	return true;
5561
5562	if (candidate.isKeyword())
5563	return WantTypeSpecifiers || WantExpressionKeywords || WantCXXNamedCasts ||
5564	WantRemainingKeywords || WantObjCSuper;
5565
5566	bool HasNonType = false;
5567	bool HasStaticMethod = false;
5568	bool HasNonStaticMethod = false;
5569	for (Decl *D : candidate) {
5570	if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(Val: D))
5571	D = FTD->getTemplatedDecl();
5572	if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Val: D)) {
5573	if (Method->isStatic())
5574	HasStaticMethod = true;
5575	else
5576	HasNonStaticMethod = true;
5577	}
5578	if (!isa<TypeDecl>(Val: D))
5579	HasNonType = true;
5580	}
5581
5582	if (IsAddressOfOperand && HasNonStaticMethod && !HasStaticMethod &&
5583	!candidate.getCorrectionSpecifier())
5584	return false;
5585
5586	return WantTypeSpecifiers || HasNonType;
5587	}
5588
5589	FunctionCallFilterCCC::FunctionCallFilterCCC(Sema &SemaRef, unsigned NumArgs,
5590	bool HasExplicitTemplateArgs,
5591	MemberExpr *ME)
5592	: NumArgs(NumArgs), HasExplicitTemplateArgs(HasExplicitTemplateArgs),
5593	CurContext(SemaRef.CurContext), MemberFn(ME) {
5594	WantTypeSpecifiers = false;
5595	WantFunctionLikeCasts = SemaRef.getLangOpts().CPlusPlus &&
5596	!HasExplicitTemplateArgs && NumArgs == 1;
5597	WantCXXNamedCasts = HasExplicitTemplateArgs && NumArgs == 1;
5598	WantRemainingKeywords = false;
5599	}
5600
5601	bool FunctionCallFilterCCC::ValidateCandidate(const TypoCorrection &candidate) {
5602	if (!candidate.getCorrectionDecl())
5603	return candidate.isKeyword();
5604
5605	for (auto *C : candidate) {
5606	FunctionDecl *FD = nullptr;
5607	NamedDecl *ND = C->getUnderlyingDecl();
5608	if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(Val: ND))
5609	FD = FTD->getTemplatedDecl();
5610	if (!HasExplicitTemplateArgs && !FD) {
5611	if (!(FD = dyn_cast<FunctionDecl>(Val: ND)) && isa<ValueDecl>(Val: ND)) {
5612	// If the Decl is neither a function nor a template function,
5613	// determine if it is a pointer or reference to a function. If so,
5614	// check against the number of arguments expected for the pointee.
5615	QualType ValType = cast<ValueDecl>(Val: ND)->getType();
5616	if (ValType.isNull())
5617	continue;
5618	if (ValType->isAnyPointerType() || ValType->isReferenceType())
5619	ValType = ValType->getPointeeType();
5620	if (const FunctionProtoType *FPT = ValType->getAs<FunctionProtoType>())
5621	if (FPT->getNumParams() == NumArgs)
5622	return true;
5623	}
5624	}
5625
5626	// A typo for a function-style cast can look like a function call in C++.
5627	if ((HasExplicitTemplateArgs ? getAsTypeTemplateDecl(ND) != nullptr
5628	: isa<TypeDecl>(Val: ND)) &&
5629	CurContext->getParentASTContext().getLangOpts().CPlusPlus)
5630	// Only a class or class template can take two or more arguments.
5631	return NumArgs <= 1 || HasExplicitTemplateArgs || isa<CXXRecordDecl>(Val: ND);
5632
5633	// Skip the current candidate if it is not a FunctionDecl or does not accept
5634	// the current number of arguments.
5635	if (!FD || !(FD->getNumParams() >= NumArgs &&
5636	FD->getMinRequiredArguments() <= NumArgs))
5637	continue;
5638
5639	// If the current candidate is a non-static C++ method, skip the candidate
5640	// unless the method being corrected--or the current DeclContext, if the
5641	// function being corrected is not a method--is a method in the same class
5642	// or a descendent class of the candidate's parent class.
5643	if (const auto *MD = dyn_cast<CXXMethodDecl>(Val: FD)) {
5644	if (MemberFn || !MD->isStatic()) {
5645	const auto *CurMD =
5646	MemberFn
5647	? dyn_cast_if_present<CXXMethodDecl>(Val: MemberFn->getMemberDecl())
5648	: dyn_cast_if_present<CXXMethodDecl>(Val: CurContext);
5649	const CXXRecordDecl *CurRD =
5650	CurMD ? CurMD->getParent()->getCanonicalDecl() : nullptr;
5651	const CXXRecordDecl *RD = MD->getParent()->getCanonicalDecl();
5652	if (!CurRD || (CurRD != RD && !CurRD->isDerivedFrom(Base: RD)))
5653	continue;
5654	}
5655	}
5656	return true;
5657	}
5658	return false;
5659	}
5660
5661	void Sema::diagnoseTypo(const TypoCorrection &Correction,
5662	const PartialDiagnostic &TypoDiag,
5663	bool ErrorRecovery) {
5664	diagnoseTypo(Correction, TypoDiag, PDiag(diag::note_previous_decl),
5665	ErrorRecovery);
5666	}
5667
5668	/// Find which declaration we should import to provide the definition of
5669	/// the given declaration.
5670	static const NamedDecl *getDefinitionToImport(const NamedDecl *D) {
5671	if (const auto *VD = dyn_cast<VarDecl>(Val: D))
5672	return VD->getDefinition();
5673	if (const auto *FD = dyn_cast<FunctionDecl>(Val: D))
5674	return FD->getDefinition();
5675	if (const auto *TD = dyn_cast<TagDecl>(Val: D))
5676	return TD->getDefinition();
5677	if (const auto *ID = dyn_cast<ObjCInterfaceDecl>(Val: D))
5678	return ID->getDefinition();
5679	if (const auto *PD = dyn_cast<ObjCProtocolDecl>(Val: D))
5680	return PD->getDefinition();
5681	if (const auto *TD = dyn_cast<TemplateDecl>(Val: D))
5682	if (const NamedDecl *TTD = TD->getTemplatedDecl())
5683	return getDefinitionToImport(D: TTD);
5684	return nullptr;
5685	}
5686
5687	void Sema::diagnoseMissingImport(SourceLocation Loc, const NamedDecl *Decl,
5688	MissingImportKind MIK, bool Recover) {
5689	// Suggest importing a module providing the definition of this entity, if
5690	// possible.
5691	const NamedDecl *Def = getDefinitionToImport(D: Decl);
5692	if (!Def)
5693	Def = Decl;
5694
5695	Module *Owner = getOwningModule(Def);
5696	assert(Owner && "definition of hidden declaration is not in a module");
5697
5698	llvm::SmallVector<Module*, 8> OwningModules;
5699	OwningModules.push_back(Elt: Owner);
5700	auto Merged = Context.getModulesWithMergedDefinition(Def);
5701	OwningModules.insert(I: OwningModules.end(), From: Merged.begin(), To: Merged.end());
5702
5703	diagnoseMissingImport(Loc, Def, Def->getLocation(), OwningModules, MIK,
5704	Recover);
5705	}
5706
5707	/// Get a "quoted.h" or <angled.h> include path to use in a diagnostic
5708	/// suggesting the addition of a #include of the specified file.
5709	static std::string getHeaderNameForHeader(Preprocessor &PP, FileEntryRef E,
5710	llvm::StringRef IncludingFile) {
5711	bool IsAngled = false;
5712	auto Path = PP.getHeaderSearchInfo().suggestPathToFileForDiagnostics(
5713	File: E, MainFile: IncludingFile, IsAngled: &IsAngled);
5714	return (IsAngled ? '<' : '"') + Path + (IsAngled ? '>' : '"');
5715	}
5716
5717	void Sema::diagnoseMissingImport(SourceLocation UseLoc, const NamedDecl *Decl,
5718	SourceLocation DeclLoc,
5719	ArrayRef<Module *> Modules,
5720	MissingImportKind MIK, bool Recover) {
5721	assert(!Modules.empty());
5722
5723	// See https://github.com/llvm/llvm-project/issues/73893. It is generally
5724	// confusing than helpful to show the namespace is not visible.
5725	if (isa<NamespaceDecl>(Val: Decl))
5726	return;
5727
5728	auto NotePrevious = [&] {
5729	// FIXME: Suppress the note backtrace even under
5730	// -fdiagnostics-show-note-include-stack. We don't care how this
5731	// declaration was previously reached.
5732	Diag(DeclLoc, diag::note_unreachable_entity) << (int)MIK;
5733	};
5734
5735	// Weed out duplicates from module list.
5736	llvm::SmallVector<Module*, 8> UniqueModules;
5737	llvm::SmallDenseSet<Module*, 8> UniqueModuleSet;
5738	for (auto *M : Modules) {
5739	if (M->isExplicitGlobalModule() || M->isPrivateModule())
5740	continue;
5741	if (UniqueModuleSet.insert(V: M).second)
5742	UniqueModules.push_back(Elt: M);
5743	}
5744
5745	// Try to find a suitable header-name to #include.
5746	std::string HeaderName;
5747	if (OptionalFileEntryRef Header =
5748	PP.getHeaderToIncludeForDiagnostics(IncLoc: UseLoc, MLoc: DeclLoc)) {
5749	if (const FileEntry *FE =
5750	SourceMgr.getFileEntryForID(FID: SourceMgr.getFileID(SpellingLoc: UseLoc)))
5751	HeaderName =
5752	getHeaderNameForHeader(PP, E: *Header, IncludingFile: FE->tryGetRealPathName());
5753	}
5754
5755	// If we have a #include we should suggest, or if all definition locations
5756	// were in global module fragments, don't suggest an import.
5757	if (!HeaderName.empty() || UniqueModules.empty()) {
5758	// FIXME: Find a smart place to suggest inserting a #include, and add
5759	// a FixItHint there.
5760	Diag(UseLoc, diag::err_module_unimported_use_header)
5761	<< (int)MIK << Decl << !HeaderName.empty() << HeaderName;
5762	// Produce a note showing where the entity was declared.
5763	NotePrevious();
5764	if (Recover)
5765	createImplicitModuleImportForErrorRecovery(Loc: UseLoc, Mod: Modules[0]);
5766	return;
5767	}
5768
5769	Modules = UniqueModules;
5770
5771	auto GetModuleNameForDiagnostic = [this](const Module *M) -> std::string {
5772	if (M->isModuleMapModule())
5773	return M->getFullModuleName();
5774
5775	Module *CurrentModule = getCurrentModule();
5776
5777	if (M->isImplicitGlobalModule())
5778	M = M->getTopLevelModule();
5779
5780	bool IsInTheSameModule =
5781	CurrentModule && CurrentModule->getPrimaryModuleInterfaceName() ==
5782	M->getPrimaryModuleInterfaceName();
5783
5784	// If the current module unit is in the same module with M, it is OK to show
5785	// the partition name. Otherwise, it'll be sufficient to show the primary
5786	// module name.
5787	if (IsInTheSameModule)
5788	return M->getTopLevelModuleName().str();
5789	else
5790	return M->getPrimaryModuleInterfaceName().str();
5791	};
5792
5793	if (Modules.size() > 1) {
5794	std::string ModuleList;
5795	unsigned N = 0;
5796	for (const auto *M : Modules) {
5797	ModuleList += "\n ";
5798	if (++N == 5 && N != Modules.size()) {
5799	ModuleList += "[...]";
5800	break;
5801	}
5802	ModuleList += GetModuleNameForDiagnostic(M);
5803	}
5804
5805	Diag(UseLoc, diag::err_module_unimported_use_multiple)
5806	<< (int)MIK << Decl << ModuleList;
5807	} else {
5808	// FIXME: Add a FixItHint that imports the corresponding module.
5809	Diag(UseLoc, diag::err_module_unimported_use)
5810	<< (int)MIK << Decl << GetModuleNameForDiagnostic(Modules[0]);
5811	}
5812
5813	NotePrevious();
5814
5815	// Try to recover by implicitly importing this module.
5816	if (Recover)
5817	createImplicitModuleImportForErrorRecovery(Loc: UseLoc, Mod: Modules[0]);
5818	}
5819
5820	/// Diagnose a successfully-corrected typo. Separated from the correction
5821	/// itself to allow external validation of the result, etc.
5822	///
5823	/// \param Correction The result of performing typo correction.
5824	/// \param TypoDiag The diagnostic to produce. This will have the corrected
5825	/// string added to it (and usually also a fixit).
5826	/// \param PrevNote A note to use when indicating the location of the entity to
5827	/// which we are correcting. Will have the correction string added to it.
5828	/// \param ErrorRecovery If \c true (the default), the caller is going to
5829	/// recover from the typo as if the corrected string had been typed.
5830	/// In this case, \c PDiag must be an error, and we will attach a fixit
5831	/// to it.
5832	void Sema::diagnoseTypo(const TypoCorrection &Correction,
5833	const PartialDiagnostic &TypoDiag,
5834	const PartialDiagnostic &PrevNote,
5835	bool ErrorRecovery) {
5836	std::string CorrectedStr = Correction.getAsString(LO: getLangOpts());
5837	std::string CorrectedQuotedStr = Correction.getQuoted(LO: getLangOpts());
5838	FixItHint FixTypo = FixItHint::CreateReplacement(
5839	RemoveRange: Correction.getCorrectionRange(), Code: CorrectedStr);
5840
5841	// Maybe we're just missing a module import.
5842	if (Correction.requiresImport()) {
5843	NamedDecl *Decl = Correction.getFoundDecl();
5844	assert(Decl && "import required but no declaration to import");
5845
5846	diagnoseMissingImport(Loc: Correction.getCorrectionRange().getBegin(), Decl,
5847	MIK: MissingImportKind::Declaration, Recover: ErrorRecovery);
5848	return;
5849	}
5850
5851	Diag(Correction.getCorrectionRange().getBegin(), TypoDiag)
5852	<< CorrectedQuotedStr << (ErrorRecovery ? FixTypo : FixItHint());
5853
5854	NamedDecl *ChosenDecl =
5855	Correction.isKeyword() ? nullptr : Correction.getFoundDecl();
5856	if (PrevNote.getDiagID() && ChosenDecl)
5857	Diag(ChosenDecl->getLocation(), PrevNote)
5858	<< CorrectedQuotedStr << (ErrorRecovery ? FixItHint() : FixTypo);
5859
5860	// Add any extra diagnostics.
5861	for (const PartialDiagnostic &PD : Correction.getExtraDiagnostics())
5862	Diag(Correction.getCorrectionRange().getBegin(), PD);
5863	}
5864
5865	TypoExpr *Sema::createDelayedTypo(std::unique_ptr<TypoCorrectionConsumer> TCC,
5866	TypoDiagnosticGenerator TDG,
5867	TypoRecoveryCallback TRC,
5868	SourceLocation TypoLoc) {
5869	assert(TCC && "createDelayedTypo requires a valid TypoCorrectionConsumer");
5870	auto TE = new (Context) TypoExpr(Context.DependentTy, TypoLoc);
5871	auto &State = DelayedTypos[TE];
5872	State.Consumer = std::move(TCC);
5873	State.DiagHandler = std::move(TDG);
5874	State.RecoveryHandler = std::move(TRC);
5875	if (TE)
5876	TypoExprs.push_back(Elt: TE);
5877	return TE;
5878	}
5879
5880	const Sema::TypoExprState &Sema::getTypoExprState(TypoExpr *TE) const {
5881	auto Entry = DelayedTypos.find(Key: TE);
5882	assert(Entry != DelayedTypos.end() &&
5883	"Failed to get the state for a TypoExpr!");
5884	return Entry->second;
5885	}
5886
5887	void Sema::clearDelayedTypo(TypoExpr *TE) {
5888	DelayedTypos.erase(Key: TE);
5889	}
5890
5891	void Sema::ActOnPragmaDump(Scope *S, SourceLocation IILoc, IdentifierInfo *II) {
5892	DeclarationNameInfo Name(II, IILoc);
5893	LookupResult R(*this, Name, LookupAnyName,
5894	RedeclarationKind::NotForRedeclaration);
5895	R.suppressDiagnostics();
5896	R.setHideTags(false);
5897	LookupName(R, S);
5898	R.dump();
5899	}
5900
5901	void Sema::ActOnPragmaDump(Expr *E) {
5902	E->dump();
5903	}
5904
5905	RedeclarationKind Sema::forRedeclarationInCurContext() const {
5906	// A declaration with an owning module for linkage can never link against
5907	// anything that is not visible. We don't need to check linkage here; if
5908	// the context has internal linkage, redeclaration lookup won't find things
5909	// from other TUs, and we can't safely compute linkage yet in general.
5910	if (cast<Decl>(Val: CurContext)->getOwningModuleForLinkage(/*IgnoreLinkage*/ true))
5911	return RedeclarationKind::ForVisibleRedeclaration;
5912	return RedeclarationKind::ForExternalRedeclaration;
5913	}
5914