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