1	//===--- SemaLambda.cpp - Semantic Analysis for C++11 Lambdas -------------===//
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 semantic analysis for C++ lambda expressions.
10	//
11	//===----------------------------------------------------------------------===//
12	#include "clang/Sema/SemaLambda.h"
13	#include "TypeLocBuilder.h"
14	#include "clang/AST/ASTLambda.h"
15	#include "clang/AST/CXXInheritance.h"
16	#include "clang/AST/ExprCXX.h"
17	#include "clang/AST/MangleNumberingContext.h"
18	#include "clang/Basic/TargetInfo.h"
19	#include "clang/Sema/DeclSpec.h"
20	#include "clang/Sema/Initialization.h"
21	#include "clang/Sema/Lookup.h"
22	#include "clang/Sema/Scope.h"
23	#include "clang/Sema/ScopeInfo.h"
24	#include "clang/Sema/SemaARM.h"
25	#include "clang/Sema/SemaCUDA.h"
26	#include "clang/Sema/SemaInternal.h"
27	#include "clang/Sema/SemaOpenMP.h"
28	#include "clang/Sema/SemaSYCL.h"
29	#include "clang/Sema/Template.h"
30	#include "llvm/ADT/STLExtras.h"
31	#include <optional>
32	using namespace clang;
33	using namespace sema;
34
35	/// Examines the FunctionScopeInfo stack to determine the nearest
36	/// enclosing lambda (to the current lambda) that is 'capture-ready' for
37	/// the variable referenced in the current lambda (i.e. \p VarToCapture).
38	/// If successful, returns the index into Sema's FunctionScopeInfo stack
39	/// of the capture-ready lambda's LambdaScopeInfo.
40	///
41	/// Climbs down the stack of lambdas (deepest nested lambda - i.e. current
42	/// lambda - is on top) to determine the index of the nearest enclosing/outer
43	/// lambda that is ready to capture the \p VarToCapture being referenced in
44	/// the current lambda.
45	/// As we climb down the stack, we want the index of the first such lambda -
46	/// that is the lambda with the highest index that is 'capture-ready'.
47	///
48	/// A lambda 'L' is capture-ready for 'V' (var or this) if:
49	/// - its enclosing context is non-dependent
50	/// - and if the chain of lambdas between L and the lambda in which
51	/// V is potentially used (i.e. the lambda at the top of the scope info
52	/// stack), can all capture or have already captured V.
53	/// If \p VarToCapture is 'null' then we are trying to capture 'this'.
54	///
55	/// Note that a lambda that is deemed 'capture-ready' still needs to be checked
56	/// for whether it is 'capture-capable' (see
57	/// getStackIndexOfNearestEnclosingCaptureCapableLambda), before it can truly
58	/// capture.
59	///
60	/// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
61	/// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
62	/// is at the top of the stack and has the highest index.
63	/// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
64	///
65	/// \returns An UnsignedOrNone Index that if evaluates to 'true'
66	/// contains the index (into Sema's FunctionScopeInfo stack) of the innermost
67	/// lambda which is capture-ready. If the return value evaluates to 'false'
68	/// then no lambda is capture-ready for \p VarToCapture.
69
70	static inline UnsignedOrNone getStackIndexOfNearestEnclosingCaptureReadyLambda(
71	ArrayRef<const clang::sema::FunctionScopeInfo *> FunctionScopes,
72	ValueDecl *VarToCapture) {
73	// Label failure to capture.
74	const UnsignedOrNone NoLambdaIsCaptureReady = std::nullopt;
75
76	// Ignore all inner captured regions.
77	unsigned CurScopeIndex = FunctionScopes.size() - 1;
78	while (CurScopeIndex > 0 && isa<clang::sema::CapturedRegionScopeInfo>(
79	Val: FunctionScopes[CurScopeIndex]))
80	--CurScopeIndex;
81	assert(
82	isa<clang::sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]) &&
83	"The function on the top of sema's function-info stack must be a lambda");
84
85	// If VarToCapture is null, we are attempting to capture 'this'.
86	const bool IsCapturingThis = !VarToCapture;
87	const bool IsCapturingVariable = !IsCapturingThis;
88
89	// Start with the current lambda at the top of the stack (highest index).
90	DeclContext *EnclosingDC =
91	cast<sema::LambdaScopeInfo>(Val: FunctionScopes[CurScopeIndex])->CallOperator;
92
93	do {
94	const clang::sema::LambdaScopeInfo *LSI =
95	cast<sema::LambdaScopeInfo>(Val: FunctionScopes[CurScopeIndex]);
96	// IF we have climbed down to an intervening enclosing lambda that contains
97	// the variable declaration - it obviously can/must not capture the
98	// variable.
99	// Since its enclosing DC is dependent, all the lambdas between it and the
100	// innermost nested lambda are dependent (otherwise we wouldn't have
101	// arrived here) - so we don't yet have a lambda that can capture the
102	// variable.
103	if (IsCapturingVariable &&
104	VarToCapture->getDeclContext()->Equals(DC: EnclosingDC))
105	return NoLambdaIsCaptureReady;
106
107	// For an enclosing lambda to be capture ready for an entity, all
108	// intervening lambda's have to be able to capture that entity. If even
109	// one of the intervening lambda's is not capable of capturing the entity
110	// then no enclosing lambda can ever capture that entity.
111	// For e.g.
112	// const int x = 10;
113	// [=](auto a) { #1
114	// [](auto b) { #2 <-- an intervening lambda that can never capture 'x'
115	// [=](auto c) { #3
116	// f(x, c); <-- can not lead to x's speculative capture by #1 or #2
117	// }; }; };
118	// If they do not have a default implicit capture, check to see
119	// if the entity has already been explicitly captured.
120	// If even a single dependent enclosing lambda lacks the capability
121	// to ever capture this variable, there is no further enclosing
122	// non-dependent lambda that can capture this variable.
123	if (LSI->ImpCaptureStyle == sema::LambdaScopeInfo::ImpCap_None) {
124	if (IsCapturingVariable && !LSI->isCaptured(Var: VarToCapture))
125	return NoLambdaIsCaptureReady;
126	if (IsCapturingThis && !LSI->isCXXThisCaptured())
127	return NoLambdaIsCaptureReady;
128	}
129	EnclosingDC = getLambdaAwareParentOfDeclContext(DC: EnclosingDC);
130
131	assert(CurScopeIndex);
132	--CurScopeIndex;
133	} while (!EnclosingDC->isTranslationUnit() &&
134	EnclosingDC->isDependentContext() &&
135	isLambdaCallOperator(DC: EnclosingDC));
136
137	assert(CurScopeIndex < (FunctionScopes.size() - 1));
138	// If the enclosingDC is not dependent, then the immediately nested lambda
139	// (one index above) is capture-ready.
140	if (!EnclosingDC->isDependentContext())
141	return CurScopeIndex + 1;
142	return NoLambdaIsCaptureReady;
143	}
144
145	/// Examines the FunctionScopeInfo stack to determine the nearest
146	/// enclosing lambda (to the current lambda) that is 'capture-capable' for
147	/// the variable referenced in the current lambda (i.e. \p VarToCapture).
148	/// If successful, returns the index into Sema's FunctionScopeInfo stack
149	/// of the capture-capable lambda's LambdaScopeInfo.
150	///
151	/// Given the current stack of lambdas being processed by Sema and
152	/// the variable of interest, to identify the nearest enclosing lambda (to the
153	/// current lambda at the top of the stack) that can truly capture
154	/// a variable, it has to have the following two properties:
155	/// a) 'capture-ready' - be the innermost lambda that is 'capture-ready':
156	/// - climb down the stack (i.e. starting from the innermost and examining
157	/// each outer lambda step by step) checking if each enclosing
158	/// lambda can either implicitly or explicitly capture the variable.
159	/// Record the first such lambda that is enclosed in a non-dependent
160	/// context. If no such lambda currently exists return failure.
161	/// b) 'capture-capable' - make sure the 'capture-ready' lambda can truly
162	/// capture the variable by checking all its enclosing lambdas:
163	/// - check if all outer lambdas enclosing the 'capture-ready' lambda
164	/// identified above in 'a' can also capture the variable (this is done
165	/// via tryCaptureVariable for variables and CheckCXXThisCapture for
166	/// 'this' by passing in the index of the Lambda identified in step 'a')
167	///
168	/// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
169	/// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
170	/// is at the top of the stack.
171	///
172	/// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
173	///
174	///
175	/// \returns An UnsignedOrNone Index that if evaluates to 'true'
176	/// contains the index (into Sema's FunctionScopeInfo stack) of the innermost
177	/// lambda which is capture-capable. If the return value evaluates to 'false'
178	/// then no lambda is capture-capable for \p VarToCapture.
179
180	UnsignedOrNone clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
181	ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
182	ValueDecl *VarToCapture, Sema &S) {
183
184	const UnsignedOrNone NoLambdaIsCaptureCapable = std::nullopt;
185
186	const UnsignedOrNone OptionalStackIndex =
187	getStackIndexOfNearestEnclosingCaptureReadyLambda(FunctionScopes,
188	VarToCapture);
189	if (!OptionalStackIndex)
190	return NoLambdaIsCaptureCapable;
191
192	const unsigned IndexOfCaptureReadyLambda = *OptionalStackIndex;
193	assert(((IndexOfCaptureReadyLambda != (FunctionScopes.size() - 1)) ||
194	S.getCurGenericLambda()) &&
195	"The capture ready lambda for a potential capture can only be the "
196	"current lambda if it is a generic lambda");
197
198	const sema::LambdaScopeInfo *const CaptureReadyLambdaLSI =
199	cast<sema::LambdaScopeInfo>(Val: FunctionScopes[IndexOfCaptureReadyLambda]);
200
201	// If VarToCapture is null, we are attempting to capture 'this'
202	const bool IsCapturingThis = !VarToCapture;
203	const bool IsCapturingVariable = !IsCapturingThis;
204
205	if (IsCapturingVariable) {
206	// Check if the capture-ready lambda can truly capture the variable, by
207	// checking whether all enclosing lambdas of the capture-ready lambda allow
208	// the capture - i.e. make sure it is capture-capable.
209	QualType CaptureType, DeclRefType;
210	const bool CanCaptureVariable = !S.tryCaptureVariable(
211	Var: VarToCapture,
212	/*ExprVarIsUsedInLoc*/ Loc: SourceLocation(), Kind: TryCaptureKind::Implicit,
213	/*EllipsisLoc*/ SourceLocation(),
214	/*BuildAndDiagnose*/ false, CaptureType, DeclRefType,
215	FunctionScopeIndexToStopAt: &IndexOfCaptureReadyLambda);
216	if (!CanCaptureVariable)
217	return NoLambdaIsCaptureCapable;
218	} else {
219	// Check if the capture-ready lambda can truly capture 'this' by checking
220	// whether all enclosing lambdas of the capture-ready lambda can capture
221	// 'this'.
222	const bool CanCaptureThis =
223	!S.CheckCXXThisCapture(
224	Loc: CaptureReadyLambdaLSI->PotentialThisCaptureLocation,
225	/*Explicit*/ false, /*BuildAndDiagnose*/ false,
226	FunctionScopeIndexToStopAt: &IndexOfCaptureReadyLambda);
227	if (!CanCaptureThis)
228	return NoLambdaIsCaptureCapable;
229	}
230	return IndexOfCaptureReadyLambda;
231	}
232
233	static inline TemplateParameterList *
234	getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) {
235	if (!LSI->GLTemplateParameterList && !LSI->TemplateParams.empty()) {
236	LSI->GLTemplateParameterList = TemplateParameterList::Create(
237	C: SemaRef.Context,
238	/*Template kw loc*/ TemplateLoc: SourceLocation(),
239	/*L angle loc*/ LAngleLoc: LSI->ExplicitTemplateParamsRange.getBegin(),
240	Params: LSI->TemplateParams,
241	/*R angle loc*/RAngleLoc: LSI->ExplicitTemplateParamsRange.getEnd(),
242	RequiresClause: LSI->RequiresClause.get());
243	}
244	return LSI->GLTemplateParameterList;
245	}
246
247	CXXRecordDecl *
248	Sema::createLambdaClosureType(SourceRange IntroducerRange, TypeSourceInfo *Info,
249	unsigned LambdaDependencyKind,
250	LambdaCaptureDefault CaptureDefault) {
251	DeclContext *DC = CurContext;
252
253	bool IsGenericLambda =
254	Info && getGenericLambdaTemplateParameterList(LSI: getCurLambda(), SemaRef&: *this);
255	// Start constructing the lambda class.
256	CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(
257	C: Context, DC, Info, Loc: IntroducerRange.getBegin(), DependencyKind: LambdaDependencyKind,
258	IsGeneric: IsGenericLambda, CaptureDefault);
259	DC->addDecl(D: Class);
260
261	return Class;
262	}
263
264	/// Determine whether the given context is or is enclosed in an inline
265	/// function.
266	static bool isInInlineFunction(const DeclContext *DC) {
267	while (!DC->isFileContext()) {
268	if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Val: DC))
269	if (FD->isInlined())
270	return true;
271
272	DC = DC->getLexicalParent();
273	}
274
275	return false;
276	}
277
278	std::tuple<MangleNumberingContext *, Decl *>
279	Sema::getCurrentMangleNumberContext(const DeclContext *DC) {
280	// Compute the context for allocating mangling numbers in the current
281	// expression, if the ABI requires them.
282	Decl *ManglingContextDecl = ExprEvalContexts.back().ManglingContextDecl;
283
284	enum ContextKind {
285	Normal,
286	DefaultArgument,
287	DataMember,
288	InlineVariable,
289	TemplatedVariable,
290	Concept,
291	NonInlineInModulePurview
292	} Kind = Normal;
293
294	bool IsInNonspecializedTemplate =
295	inTemplateInstantiation() || CurContext->isDependentContext();
296
297	// Default arguments of member function parameters that appear in a class
298	// definition, as well as the initializers of data members, receive special
299	// treatment. Identify them.
300	Kind = [&]() {
301	if (!ManglingContextDecl)
302	return Normal;
303
304	if (auto *ND = dyn_cast<NamedDecl>(Val: ManglingContextDecl)) {
305	// See discussion in https://github.com/itanium-cxx-abi/cxx-abi/issues/186
306	//
307	// zygoloid:
308	// Yeah, I think the only cases left where lambdas don't need a
309	// mangling are when they have (effectively) internal linkage or appear
310	// in a non-inline function in a non-module translation unit.
311	Module *M = ManglingContextDecl->getOwningModule();
312	if (M && M->getTopLevelModule()->isNamedModuleUnit() &&
313	ND->isExternallyVisible())
314	return NonInlineInModulePurview;
315	}
316
317	if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(Val: ManglingContextDecl)) {
318	if (const DeclContext *LexicalDC
319	= Param->getDeclContext()->getLexicalParent())
320	if (LexicalDC->isRecord())
321	return DefaultArgument;
322	} else if (VarDecl *Var = dyn_cast<VarDecl>(Val: ManglingContextDecl)) {
323	if (Var->getMostRecentDecl()->isInline())
324	return InlineVariable;
325
326	if (Var->getDeclContext()->isRecord() && IsInNonspecializedTemplate)
327	return TemplatedVariable;
328
329	if (Var->getDescribedVarTemplate())
330	return TemplatedVariable;
331
332	if (auto *VTS = dyn_cast<VarTemplateSpecializationDecl>(Val: Var)) {
333	if (!VTS->isExplicitSpecialization())
334	return TemplatedVariable;
335	}
336	} else if (isa<FieldDecl>(Val: ManglingContextDecl)) {
337	return DataMember;
338	} else if (isa<ImplicitConceptSpecializationDecl>(Val: ManglingContextDecl)) {
339	return Concept;
340	}
341
342	return Normal;
343	}();
344
345	// Itanium ABI [5.1.7]:
346	// In the following contexts [...] the one-definition rule requires closure
347	// types in different translation units to "correspond":
348	switch (Kind) {
349	case Normal: {
350	// -- the bodies of inline or templated functions
351	if ((IsInNonspecializedTemplate &&
352	!(ManglingContextDecl && isa<ParmVarDecl>(Val: ManglingContextDecl))) ||
353	isInInlineFunction(DC: CurContext)) {
354	while (auto *CD = dyn_cast<CapturedDecl>(Val: DC))
355	DC = CD->getParent();
356	return std::make_tuple(args: &Context.getManglingNumberContext(DC), args: nullptr);
357	}
358
359	return std::make_tuple(args: nullptr, args: nullptr);
360	}
361
362	case NonInlineInModulePurview:
363	case Concept:
364	// Concept definitions aren't code generated and thus aren't mangled,
365	// however the ManglingContextDecl is important for the purposes of
366	// re-forming the template argument list of the lambda for constraint
367	// evaluation.
368	case DataMember:
369	// -- default member initializers
370	case DefaultArgument:
371	// -- default arguments appearing in class definitions
372	case InlineVariable:
373	case TemplatedVariable:
374	// -- the initializers of inline or templated variables
375	return std::make_tuple(
376	args: &Context.getManglingNumberContext(ASTContext::NeedExtraManglingDecl,
377	D: ManglingContextDecl),
378	args&: ManglingContextDecl);
379	}
380
381	llvm_unreachable("unexpected context");
382	}
383
384	static QualType
385	buildTypeForLambdaCallOperator(Sema &S, clang::CXXRecordDecl *Class,
386	TemplateParameterList *TemplateParams,
387	TypeSourceInfo *MethodTypeInfo) {
388	assert(MethodTypeInfo && "expected a non null type");
389
390	QualType MethodType = MethodTypeInfo->getType();
391	// If a lambda appears in a dependent context or is a generic lambda (has
392	// template parameters) and has an 'auto' return type, deduce it to a
393	// dependent type.
394	if (Class->isDependentContext() || TemplateParams) {
395	const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
396	QualType Result = FPT->getReturnType();
397	if (Result->isUndeducedType()) {
398	Result = S.SubstAutoTypeDependent(TypeWithAuto: Result);
399	MethodType = S.Context.getFunctionType(ResultTy: Result, Args: FPT->getParamTypes(),
400	EPI: FPT->getExtProtoInfo());
401	}
402	}
403	return MethodType;
404	}
405
406	// [C++2b] [expr.prim.lambda.closure] p4
407	// Given a lambda with a lambda-capture, the type of the explicit object
408	// parameter, if any, of the lambda's function call operator (possibly
409	// instantiated from a function call operator template) shall be either:
410	// - the closure type,
411	// - class type publicly and unambiguously derived from the closure type, or
412	// - a reference to a possibly cv-qualified such type.
413	bool Sema::DiagnoseInvalidExplicitObjectParameterInLambda(
414	CXXMethodDecl *Method, SourceLocation CallLoc) {
415	if (!isLambdaCallWithExplicitObjectParameter(DC: Method))
416	return false;
417	CXXRecordDecl *RD = Method->getParent();
418	if (Method->getType()->isDependentType())
419	return false;
420	if (RD->isCapturelessLambda())
421	return false;
422
423	ParmVarDecl *Param = Method->getParamDecl(i: 0);
424	QualType ExplicitObjectParameterType = Param->getType()
425	.getNonReferenceType()
426	.getUnqualifiedType()
427	.getDesugaredType(Context: getASTContext());
428	QualType LambdaType = getASTContext().getRecordType(Decl: RD);
429	if (LambdaType == ExplicitObjectParameterType)
430	return false;
431
432	// Don't check the same instantiation twice.
433	//
434	// If this call operator is ill-formed, there is no point in issuing
435	// a diagnostic every time it is called because the problem is in the
436	// definition of the derived type, not at the call site.
437	//
438	// FIXME: Move this check to where we instantiate the method? This should
439	// be possible, but the naive approach of just marking the method as invalid
440	// leads to us emitting more diagnostics than we should have to for this case
441	// (1 error here *and* 1 error about there being no matching overload at the
442	// call site). It might be possible to avoid that by also checking if there
443	// is an empty cast path for the method stored in the context (signalling that
444	// we've already diagnosed it) and then just not building the call, but that
445	// doesn't really seem any simpler than diagnosing it at the call site...
446	auto [It, Inserted] = Context.LambdaCastPaths.try_emplace(Key: Method);
447	if (!Inserted)
448	return It->second.empty();
449
450	CXXCastPath &Path = It->second;
451	CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
452	/*DetectVirtual=*/false);
453	if (!IsDerivedFrom(Loc: RD->getLocation(), Derived: ExplicitObjectParameterType, Base: LambdaType,
454	Paths)) {
455	Diag(Loc: Param->getLocation(), DiagID: diag::err_invalid_explicit_object_type_in_lambda)
456	<< ExplicitObjectParameterType;
457	return true;
458	}
459
460	if (Paths.isAmbiguous(BaseType: LambdaType->getCanonicalTypeUnqualified())) {
461	std::string PathsDisplay = getAmbiguousPathsDisplayString(Paths);
462	Diag(Loc: CallLoc, DiagID: diag::err_explicit_object_lambda_ambiguous_base)
463	<< LambdaType << PathsDisplay;
464	return true;
465	}
466
467	if (CheckBaseClassAccess(AccessLoc: CallLoc, Base: LambdaType, Derived: ExplicitObjectParameterType,
468	Path: Paths.front(),
469	DiagID: diag::err_explicit_object_lambda_inaccessible_base))
470	return true;
471
472	BuildBasePathArray(Paths, BasePath&: Path);
473	return false;
474	}
475
476	void Sema::handleLambdaNumbering(
477	CXXRecordDecl *Class, CXXMethodDecl *Method,
478	std::optional<CXXRecordDecl::LambdaNumbering> NumberingOverride) {
479	if (NumberingOverride) {
480	Class->setLambdaNumbering(*NumberingOverride);
481	return;
482	}
483
484	ContextRAII ManglingContext(*this, Class->getDeclContext());
485
486	auto getMangleNumberingContext =
487	[this](CXXRecordDecl *Class,
488	Decl *ManglingContextDecl) -> MangleNumberingContext * {
489	// Get mangle numbering context if there's any extra decl context.
490	if (ManglingContextDecl)
491	return &Context.getManglingNumberContext(
492	ASTContext::NeedExtraManglingDecl, D: ManglingContextDecl);
493	// Otherwise, from that lambda's decl context.
494	auto DC = Class->getDeclContext();
495	while (auto *CD = dyn_cast<CapturedDecl>(Val: DC))
496	DC = CD->getParent();
497	return &Context.getManglingNumberContext(DC);
498	};
499
500	CXXRecordDecl::LambdaNumbering Numbering;
501	MangleNumberingContext *MCtx;
502	std::tie(args&: MCtx, args&: Numbering.ContextDecl) =
503	getCurrentMangleNumberContext(DC: Class->getDeclContext());
504	if (!MCtx && (getLangOpts().CUDA || getLangOpts().SYCLIsDevice ||
505	getLangOpts().SYCLIsHost)) {
506	// Force lambda numbering in CUDA/HIP as we need to name lambdas following
507	// ODR. Both device- and host-compilation need to have a consistent naming
508	// on kernel functions. As lambdas are potential part of these `__global__`
509	// function names, they needs numbering following ODR.
510	// Also force for SYCL, since we need this for the
511	// __builtin_sycl_unique_stable_name implementation, which depends on lambda
512	// mangling.
513	MCtx = getMangleNumberingContext(Class, Numbering.ContextDecl);
514	assert(MCtx && "Retrieving mangle numbering context failed!");
515	Numbering.HasKnownInternalLinkage = true;
516	}
517	if (MCtx) {
518	Numbering.IndexInContext = MCtx->getNextLambdaIndex();
519	Numbering.ManglingNumber = MCtx->getManglingNumber(CallOperator: Method);
520	Numbering.DeviceManglingNumber = MCtx->getDeviceManglingNumber(Method);
521	Class->setLambdaNumbering(Numbering);
522
523	if (auto *Source =
524	dyn_cast_or_null<ExternalSemaSource>(Val: Context.getExternalSource()))
525	Source->AssignedLambdaNumbering(Lambda: Class);
526	}
527	}
528
529	static void buildLambdaScopeReturnType(Sema &S, LambdaScopeInfo *LSI,
530	CXXMethodDecl *CallOperator,
531	bool ExplicitResultType) {
532	if (ExplicitResultType) {
533	LSI->HasImplicitReturnType = false;
534	LSI->ReturnType = CallOperator->getReturnType();
535	if (!LSI->ReturnType->isDependentType() && !LSI->ReturnType->isVoidType())
536	S.RequireCompleteType(Loc: CallOperator->getBeginLoc(), T: LSI->ReturnType,
537	DiagID: diag::err_lambda_incomplete_result);
538	} else {
539	LSI->HasImplicitReturnType = true;
540	}
541	}
542
543	void Sema::buildLambdaScope(LambdaScopeInfo *LSI, CXXMethodDecl *CallOperator,
544	SourceRange IntroducerRange,
545	LambdaCaptureDefault CaptureDefault,
546	SourceLocation CaptureDefaultLoc,
547	bool ExplicitParams, bool Mutable) {
548	LSI->CallOperator = CallOperator;
549	CXXRecordDecl *LambdaClass = CallOperator->getParent();
550	LSI->Lambda = LambdaClass;
551	if (CaptureDefault == LCD_ByCopy)
552	LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
553	else if (CaptureDefault == LCD_ByRef)
554	LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
555	LSI->CaptureDefaultLoc = CaptureDefaultLoc;
556	LSI->IntroducerRange = IntroducerRange;
557	LSI->ExplicitParams = ExplicitParams;
558	LSI->Mutable = Mutable;
559	}
560
561	void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
562	LSI->finishedExplicitCaptures();
563	}
564
565	void Sema::ActOnLambdaExplicitTemplateParameterList(
566	LambdaIntroducer &Intro, SourceLocation LAngleLoc,
567	ArrayRef<NamedDecl *> TParams, SourceLocation RAngleLoc,
568	ExprResult RequiresClause) {
569	LambdaScopeInfo *LSI = getCurLambda();
570	assert(LSI && "Expected a lambda scope");
571	assert(LSI->NumExplicitTemplateParams == 0 &&
572	"Already acted on explicit template parameters");
573	assert(LSI->TemplateParams.empty() &&
574	"Explicit template parameters should come "
575	"before invented (auto) ones");
576	assert(!TParams.empty() &&
577	"No template parameters to act on");
578	LSI->TemplateParams.append(in_start: TParams.begin(), in_end: TParams.end());
579	LSI->NumExplicitTemplateParams = TParams.size();
580	LSI->ExplicitTemplateParamsRange = {LAngleLoc, RAngleLoc};
581	LSI->RequiresClause = RequiresClause;
582	}
583
584	/// If this expression is an enumerator-like expression of some type
585	/// T, return the type T; otherwise, return null.
586	///
587	/// Pointer comparisons on the result here should always work because
588	/// it's derived from either the parent of an EnumConstantDecl
589	/// (i.e. the definition) or the declaration returned by
590	/// EnumType::getDecl() (i.e. the definition).
591	static EnumDecl *findEnumForBlockReturn(Expr *E) {
592	// An expression is an enumerator-like expression of type T if,
593	// ignoring parens and parens-like expressions:
594	E = E->IgnoreParens();
595
596	// - it is an enumerator whose enum type is T or
597	if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Val: E)) {
598	if (EnumConstantDecl *D
599	= dyn_cast<EnumConstantDecl>(Val: DRE->getDecl())) {
600	return cast<EnumDecl>(Val: D->getDeclContext());
601	}
602	return nullptr;
603	}
604
605	// - it is a comma expression whose RHS is an enumerator-like
606	// expression of type T or
607	if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Val: E)) {
608	if (BO->getOpcode() == BO_Comma)
609	return findEnumForBlockReturn(E: BO->getRHS());
610	return nullptr;
611	}
612
613	// - it is a statement-expression whose value expression is an
614	// enumerator-like expression of type T or
615	if (StmtExpr *SE = dyn_cast<StmtExpr>(Val: E)) {
616	if (Expr *last = dyn_cast_or_null<Expr>(Val: SE->getSubStmt()->body_back()))
617	return findEnumForBlockReturn(E: last);
618	return nullptr;
619	}
620
621	// - it is a ternary conditional operator (not the GNU ?:
622	// extension) whose second and third operands are
623	// enumerator-like expressions of type T or
624	if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(Val: E)) {
625	if (EnumDecl *ED = findEnumForBlockReturn(E: CO->getTrueExpr()))
626	if (ED == findEnumForBlockReturn(E: CO->getFalseExpr()))
627	return ED;
628	return nullptr;
629	}
630
631	// (implicitly:)
632	// - it is an implicit integral conversion applied to an
633	// enumerator-like expression of type T or
634	if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Val: E)) {
635	// We can sometimes see integral conversions in valid
636	// enumerator-like expressions.
637	if (ICE->getCastKind() == CK_IntegralCast)
638	return findEnumForBlockReturn(E: ICE->getSubExpr());
639
640	// Otherwise, just rely on the type.
641	}
642
643	// - it is an expression of that formal enum type.
644	if (const EnumType *ET = E->getType()->getAs<EnumType>()) {
645	return ET->getDecl();
646	}
647
648	// Otherwise, nope.
649	return nullptr;
650	}
651
652	/// Attempt to find a type T for which the returned expression of the
653	/// given statement is an enumerator-like expression of that type.
654	static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
655	if (Expr *retValue = ret->getRetValue())
656	return findEnumForBlockReturn(E: retValue);
657	return nullptr;
658	}
659
660	/// Attempt to find a common type T for which all of the returned
661	/// expressions in a block are enumerator-like expressions of that
662	/// type.
663	static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
664	ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
665
666	// Try to find one for the first return.
667	EnumDecl *ED = findEnumForBlockReturn(ret: *i);
668	if (!ED) return nullptr;
669
670	// Check that the rest of the returns have the same enum.
671	for (++i; i != e; ++i) {
672	if (findEnumForBlockReturn(ret: *i) != ED)
673	return nullptr;
674	}
675
676	// Never infer an anonymous enum type.
677	if (!ED->hasNameForLinkage()) return nullptr;
678
679	return ED;
680	}
681
682	/// Adjust the given return statements so that they formally return
683	/// the given type. It should require, at most, an IntegralCast.
684	static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
685	QualType returnType) {
686	for (ArrayRef<ReturnStmt*>::iterator
687	i = returns.begin(), e = returns.end(); i != e; ++i) {
688	ReturnStmt *ret = *i;
689	Expr *retValue = ret->getRetValue();
690	if (S.Context.hasSameType(T1: retValue->getType(), T2: returnType))
691	continue;
692
693	// Right now we only support integral fixup casts.
694	assert(returnType->isIntegralOrUnscopedEnumerationType());
695	assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
696
697	ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(Val: retValue);
698
699	Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
700	E = ImplicitCastExpr::Create(Context: S.Context, T: returnType, Kind: CK_IntegralCast, Operand: E,
701	/*base path*/ BasePath: nullptr, Cat: VK_PRValue,
702	FPO: FPOptionsOverride());
703	if (cleanups) {
704	cleanups->setSubExpr(E);
705	} else {
706	ret->setRetValue(E);
707	}
708	}
709	}
710
711	void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
712	assert(CSI.HasImplicitReturnType);
713	// If it was ever a placeholder, it had to been deduced to DependentTy.
714	assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
715	assert((!isa<LambdaScopeInfo>(CSI) || !getLangOpts().CPlusPlus14) &&
716	"lambda expressions use auto deduction in C++14 onwards");
717
718	// C++ core issue 975:
719	// If a lambda-expression does not include a trailing-return-type,
720	// it is as if the trailing-return-type denotes the following type:
721	// - if there are no return statements in the compound-statement,
722	// or all return statements return either an expression of type
723	// void or no expression or braced-init-list, the type void;
724	// - otherwise, if all return statements return an expression
725	// and the types of the returned expressions after
726	// lvalue-to-rvalue conversion (4.1 [conv.lval]),
727	// array-to-pointer conversion (4.2 [conv.array]), and
728	// function-to-pointer conversion (4.3 [conv.func]) are the
729	// same, that common type;
730	// - otherwise, the program is ill-formed.
731	//
732	// C++ core issue 1048 additionally removes top-level cv-qualifiers
733	// from the types of returned expressions to match the C++14 auto
734	// deduction rules.
735	//
736	// In addition, in blocks in non-C++ modes, if all of the return
737	// statements are enumerator-like expressions of some type T, where
738	// T has a name for linkage, then we infer the return type of the
739	// block to be that type.
740
741	// First case: no return statements, implicit void return type.
742	ASTContext &Ctx = getASTContext();
743	if (CSI.Returns.empty()) {
744	// It's possible there were simply no /valid/ return statements.
745	// In this case, the first one we found may have at least given us a type.
746	if (CSI.ReturnType.isNull())
747	CSI.ReturnType = Ctx.VoidTy;
748	return;
749	}
750
751	// Second case: at least one return statement has dependent type.
752	// Delay type checking until instantiation.
753	assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
754	if (CSI.ReturnType->isDependentType())
755	return;
756
757	// Try to apply the enum-fuzz rule.
758	if (!getLangOpts().CPlusPlus) {
759	assert(isa<BlockScopeInfo>(CSI));
760	const EnumDecl *ED = findCommonEnumForBlockReturns(returns: CSI.Returns);
761	if (ED) {
762	CSI.ReturnType = Context.getTypeDeclType(Decl: ED);
763	adjustBlockReturnsToEnum(S&: *this, returns: CSI.Returns, returnType: CSI.ReturnType);
764	return;
765	}
766	}
767
768	// Third case: only one return statement. Don't bother doing extra work!
769	if (CSI.Returns.size() == 1)
770	return;
771
772	// General case: many return statements.
773	// Check that they all have compatible return types.
774
775	// We require the return types to strictly match here.
776	// Note that we've already done the required promotions as part of
777	// processing the return statement.
778	for (const ReturnStmt *RS : CSI.Returns) {
779	const Expr *RetE = RS->getRetValue();
780
781	QualType ReturnType =
782	(RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
783	if (Context.getCanonicalFunctionResultType(ResultType: ReturnType) ==
784	Context.getCanonicalFunctionResultType(ResultType: CSI.ReturnType)) {
785	// Use the return type with the strictest possible nullability annotation.
786	auto RetTyNullability = ReturnType->getNullability();
787	auto BlockNullability = CSI.ReturnType->getNullability();
788	if (BlockNullability &&
789	(!RetTyNullability ||
790	hasWeakerNullability(L: *RetTyNullability, R: *BlockNullability)))
791	CSI.ReturnType = ReturnType;
792	continue;
793	}
794
795	// FIXME: This is a poor diagnostic for ReturnStmts without expressions.
796	// TODO: It's possible that the *first* return is the divergent one.
797	Diag(Loc: RS->getBeginLoc(),
798	DiagID: diag::err_typecheck_missing_return_type_incompatible)
799	<< ReturnType << CSI.ReturnType << isa<LambdaScopeInfo>(Val: CSI);
800	// Continue iterating so that we keep emitting diagnostics.
801	}
802	}
803
804	QualType Sema::buildLambdaInitCaptureInitialization(
805	SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
806	UnsignedOrNone NumExpansions, IdentifierInfo *Id, bool IsDirectInit,
807	Expr *&Init) {
808	// Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
809	// deduce against.
810	QualType DeductType = Context.getAutoDeductType();
811	TypeLocBuilder TLB;
812	AutoTypeLoc TL = TLB.push<AutoTypeLoc>(T: DeductType);
813	TL.setNameLoc(Loc);
814	if (ByRef) {
815	DeductType = BuildReferenceType(T: DeductType, LValueRef: true, Loc, Entity: Id);
816	assert(!DeductType.isNull() && "can't build reference to auto");
817	TLB.push<ReferenceTypeLoc>(T: DeductType).setSigilLoc(Loc);
818	}
819	if (EllipsisLoc.isValid()) {
820	if (Init->containsUnexpandedParameterPack()) {
821	Diag(Loc: EllipsisLoc, DiagID: getLangOpts().CPlusPlus20
822	? diag::warn_cxx17_compat_init_capture_pack
823	: diag::ext_init_capture_pack);
824	DeductType = Context.getPackExpansionType(Pattern: DeductType, NumExpansions,
825	/*ExpectPackInType=*/false);
826	TLB.push<PackExpansionTypeLoc>(T: DeductType).setEllipsisLoc(EllipsisLoc);
827	} else {
828	// Just ignore the ellipsis for now and form a non-pack variable. We'll
829	// diagnose this later when we try to capture it.
830	}
831	}
832	TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, T: DeductType);
833
834	// Deduce the type of the init capture.
835	QualType DeducedType = deduceVarTypeFromInitializer(
836	/*VarDecl*/VDecl: nullptr, Name: DeclarationName(Id), Type: DeductType, TSI,
837	Range: SourceRange(Loc, Loc), DirectInit: IsDirectInit, Init);
838	if (DeducedType.isNull())
839	return QualType();
840
841	// Are we a non-list direct initialization?
842	ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Val: Init);
843
844	// Perform initialization analysis and ensure any implicit conversions
845	// (such as lvalue-to-rvalue) are enforced.
846	InitializedEntity Entity =
847	InitializedEntity::InitializeLambdaCapture(VarID: Id, FieldType: DeducedType, Loc);
848	InitializationKind Kind =
849	IsDirectInit
850	? (CXXDirectInit ? InitializationKind::CreateDirect(
851	InitLoc: Loc, LParenLoc: Init->getBeginLoc(), RParenLoc: Init->getEndLoc())
852	: InitializationKind::CreateDirectList(InitLoc: Loc))
853	: InitializationKind::CreateCopy(InitLoc: Loc, EqualLoc: Init->getBeginLoc());
854
855	MultiExprArg Args = Init;
856	if (CXXDirectInit)
857	Args =
858	MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
859	QualType DclT;
860	InitializationSequence InitSeq(*this, Entity, Kind, Args);
861	ExprResult Result = InitSeq.Perform(S&: *this, Entity, Kind, Args, ResultType: &DclT);
862
863	if (Result.isInvalid())
864	return QualType();
865
866	Init = Result.getAs<Expr>();
867	return DeducedType;
868	}
869
870	VarDecl *Sema::createLambdaInitCaptureVarDecl(
871	SourceLocation Loc, QualType InitCaptureType, SourceLocation EllipsisLoc,
872	IdentifierInfo *Id, unsigned InitStyle, Expr *Init, DeclContext *DeclCtx) {
873	// FIXME: Retain the TypeSourceInfo from buildLambdaInitCaptureInitialization
874	// rather than reconstructing it here.
875	TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(T: InitCaptureType, Loc);
876	if (auto PETL = TSI->getTypeLoc().getAs<PackExpansionTypeLoc>())
877	PETL.setEllipsisLoc(EllipsisLoc);
878
879	// Create a dummy variable representing the init-capture. This is not actually
880	// used as a variable, and only exists as a way to name and refer to the
881	// init-capture.
882	// FIXME: Pass in separate source locations for '&' and identifier.
883	VarDecl *NewVD = VarDecl::Create(C&: Context, DC: DeclCtx, StartLoc: Loc, IdLoc: Loc, Id,
884	T: InitCaptureType, TInfo: TSI, S: SC_Auto);
885	NewVD->setInitCapture(true);
886	NewVD->setReferenced(true);
887	// FIXME: Pass in a VarDecl::InitializationStyle.
888	NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
889	NewVD->markUsed(C&: Context);
890	NewVD->setInit(Init);
891	if (NewVD->isParameterPack())
892	getCurLambda()->LocalPacks.push_back(Elt: NewVD);
893	return NewVD;
894	}
895
896	void Sema::addInitCapture(LambdaScopeInfo *LSI, VarDecl *Var, bool ByRef) {
897	assert(Var->isInitCapture() && "init capture flag should be set");
898	LSI->addCapture(Var, /*isBlock=*/false, isByref: ByRef,
899	/*isNested=*/false, Loc: Var->getLocation(), EllipsisLoc: SourceLocation(),
900	CaptureType: Var->getType(), /*Invalid=*/false);
901	}
902
903	// Unlike getCurLambda, getCurrentLambdaScopeUnsafe doesn't
904	// check that the current lambda is in a consistent or fully constructed state.
905	static LambdaScopeInfo *getCurrentLambdaScopeUnsafe(Sema &S) {
906	assert(!S.FunctionScopes.empty());
907	return cast<LambdaScopeInfo>(Val: S.FunctionScopes[S.FunctionScopes.size() - 1]);
908	}
909
910	static TypeSourceInfo *
911	getDummyLambdaType(Sema &S, SourceLocation Loc = SourceLocation()) {
912	// C++11 [expr.prim.lambda]p4:
913	// If a lambda-expression does not include a lambda-declarator, it is as
914	// if the lambda-declarator were ().
915	FunctionProtoType::ExtProtoInfo EPI(S.Context.getDefaultCallingConvention(
916	/*IsVariadic=*/false, /*IsCXXMethod=*/true));
917	EPI.HasTrailingReturn = true;
918	EPI.TypeQuals.addConst();
919	LangAS AS = S.getDefaultCXXMethodAddrSpace();
920	if (AS != LangAS::Default)
921	EPI.TypeQuals.addAddressSpace(space: AS);
922
923	// C++1y [expr.prim.lambda]:
924	// The lambda return type is 'auto', which is replaced by the
925	// trailing-return type if provided and/or deduced from 'return'
926	// statements
927	// We don't do this before C++1y, because we don't support deduced return
928	// types there.
929	QualType DefaultTypeForNoTrailingReturn = S.getLangOpts().CPlusPlus14
930	? S.Context.getAutoDeductType()
931	: S.Context.DependentTy;
932	QualType MethodTy =
933	S.Context.getFunctionType(ResultTy: DefaultTypeForNoTrailingReturn, Args: {}, EPI);
934	return S.Context.getTrivialTypeSourceInfo(T: MethodTy, Loc);
935	}
936
937	static TypeSourceInfo *getLambdaType(Sema &S, LambdaIntroducer &Intro,
938	Declarator &ParamInfo, Scope *CurScope,
939	SourceLocation Loc,
940	bool &ExplicitResultType) {
941
942	ExplicitResultType = false;
943
944	assert(
945	(ParamInfo.getDeclSpec().getStorageClassSpec() ==
946	DeclSpec::SCS_unspecified ||
947	ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static) &&
948	"Unexpected storage specifier");
949	bool IsLambdaStatic =
950	ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static;
951
952	TypeSourceInfo *MethodTyInfo;
953
954	if (ParamInfo.getNumTypeObjects() == 0) {
955	MethodTyInfo = getDummyLambdaType(S, Loc);
956	} else {
957	// Check explicit parameters
958	S.CheckExplicitObjectLambda(D&: ParamInfo);
959
960	DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
961
962	bool HasExplicitObjectParameter =
963	ParamInfo.isExplicitObjectMemberFunction();
964
965	ExplicitResultType = FTI.hasTrailingReturnType();
966	if (!FTI.hasMutableQualifier() && !IsLambdaStatic &&
967	!HasExplicitObjectParameter)
968	FTI.getOrCreateMethodQualifiers().SetTypeQual(T: DeclSpec::TQ_const, Loc);
969
970	if (ExplicitResultType && S.getLangOpts().HLSL) {
971	QualType RetTy = FTI.getTrailingReturnType().get();
972	if (!RetTy.isNull()) {
973	// HLSL does not support specifying an address space on a lambda return
974	// type.
975	LangAS AddressSpace = RetTy.getAddressSpace();
976	if (AddressSpace != LangAS::Default)
977	S.Diag(Loc: FTI.getTrailingReturnTypeLoc(),
978	DiagID: diag::err_return_value_with_address_space);
979	}
980	}
981
982	MethodTyInfo = S.GetTypeForDeclarator(D&: ParamInfo);
983	assert(MethodTyInfo && "no type from lambda-declarator");
984
985	// Check for unexpanded parameter packs in the method type.
986	if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
987	S.DiagnoseUnexpandedParameterPack(Loc: Intro.Range.getBegin(), T: MethodTyInfo,
988	UPPC: S.UPPC_DeclarationType);
989	}
990	return MethodTyInfo;
991	}
992
993	CXXMethodDecl *Sema::CreateLambdaCallOperator(SourceRange IntroducerRange,
994	CXXRecordDecl *Class) {
995
996	// C++20 [expr.prim.lambda.closure]p3:
997	// The closure type for a lambda-expression has a public inline function
998	// call operator (for a non-generic lambda) or function call operator
999	// template (for a generic lambda) whose parameters and return type are
1000	// described by the lambda-expression's parameter-declaration-clause
1001	// and trailing-return-type respectively.
1002	DeclarationName MethodName =
1003	Context.DeclarationNames.getCXXOperatorName(Op: OO_Call);
1004	DeclarationNameLoc MethodNameLoc =
1005	DeclarationNameLoc::makeCXXOperatorNameLoc(Range: IntroducerRange.getBegin());
1006	CXXMethodDecl *Method = CXXMethodDecl::Create(
1007	C&: Context, RD: Class, StartLoc: SourceLocation(),
1008	NameInfo: DeclarationNameInfo(MethodName, IntroducerRange.getBegin(),
1009	MethodNameLoc),
1010	T: QualType(), /*Tinfo=*/TInfo: nullptr, SC: SC_None,
1011	UsesFPIntrin: getCurFPFeatures().isFPConstrained(),
1012	/*isInline=*/true, ConstexprKind: ConstexprSpecKind::Unspecified, EndLocation: SourceLocation(),
1013	/*TrailingRequiresClause=*/{});
1014	Method->setAccess(AS_public);
1015	return Method;
1016	}
1017
1018	void Sema::AddTemplateParametersToLambdaCallOperator(
1019	CXXMethodDecl *CallOperator, CXXRecordDecl *Class,
1020	TemplateParameterList *TemplateParams) {
1021	assert(TemplateParams && "no template parameters");
1022	FunctionTemplateDecl *TemplateMethod = FunctionTemplateDecl::Create(
1023	C&: Context, DC: Class, L: CallOperator->getLocation(), Name: CallOperator->getDeclName(),
1024	Params: TemplateParams, Decl: CallOperator);
1025	TemplateMethod->setAccess(AS_public);
1026	CallOperator->setDescribedFunctionTemplate(TemplateMethod);
1027	}
1028
1029	void Sema::CompleteLambdaCallOperator(
1030	CXXMethodDecl *Method, SourceLocation LambdaLoc,
1031	SourceLocation CallOperatorLoc,
1032	const AssociatedConstraint &TrailingRequiresClause,
1033	TypeSourceInfo *MethodTyInfo, ConstexprSpecKind ConstexprKind,
1034	StorageClass SC, ArrayRef<ParmVarDecl *> Params,
1035	bool HasExplicitResultType) {
1036
1037	LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(S&: *this);
1038
1039	if (TrailingRequiresClause)
1040	Method->setTrailingRequiresClause(TrailingRequiresClause);
1041
1042	TemplateParameterList *TemplateParams =
1043	getGenericLambdaTemplateParameterList(LSI, SemaRef&: *this);
1044
1045	DeclContext *DC = Method->getLexicalDeclContext();
1046	// DeclContext::addDecl() assumes that the DeclContext we're adding to is the
1047	// lexical context of the Method. Do so.
1048	Method->setLexicalDeclContext(LSI->Lambda);
1049	if (TemplateParams) {
1050	FunctionTemplateDecl *TemplateMethod =
1051	Method->getDescribedFunctionTemplate();
1052	assert(TemplateMethod &&
1053	"AddTemplateParametersToLambdaCallOperator should have been called");
1054
1055	LSI->Lambda->addDecl(D: TemplateMethod);
1056	TemplateMethod->setLexicalDeclContext(DC);
1057	} else {
1058	LSI->Lambda->addDecl(D: Method);
1059	}
1060	LSI->Lambda->setLambdaIsGeneric(TemplateParams);
1061	LSI->Lambda->setLambdaTypeInfo(MethodTyInfo);
1062
1063	Method->setLexicalDeclContext(DC);
1064	Method->setLocation(LambdaLoc);
1065	Method->setInnerLocStart(CallOperatorLoc);
1066	Method->setTypeSourceInfo(MethodTyInfo);
1067	Method->setType(buildTypeForLambdaCallOperator(S&: *this, Class: LSI->Lambda,
1068	TemplateParams, MethodTypeInfo: MethodTyInfo));
1069	Method->setConstexprKind(ConstexprKind);
1070	Method->setStorageClass(SC);
1071	if (!Params.empty()) {
1072	CheckParmsForFunctionDef(Parameters: Params, /*CheckParameterNames=*/false);
1073	Method->setParams(Params);
1074	for (auto P : Method->parameters()) {
1075	assert(P && "null in a parameter list");
1076	P->setOwningFunction(Method);
1077	}
1078	}
1079
1080	buildLambdaScopeReturnType(S&: *this, LSI, CallOperator: Method, ExplicitResultType: HasExplicitResultType);
1081	}
1082
1083	void Sema::ActOnLambdaExpressionAfterIntroducer(LambdaIntroducer &Intro,
1084	Scope *CurrentScope) {
1085
1086	LambdaScopeInfo *LSI = getCurLambda();
1087	assert(LSI && "LambdaScopeInfo should be on stack!");
1088
1089	if (Intro.Default == LCD_ByCopy)
1090	LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
1091	else if (Intro.Default == LCD_ByRef)
1092	LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
1093	LSI->CaptureDefaultLoc = Intro.DefaultLoc;
1094	LSI->IntroducerRange = Intro.Range;
1095	LSI->AfterParameterList = false;
1096
1097	assert(LSI->NumExplicitTemplateParams == 0);
1098
1099	// Determine if we're within a context where we know that the lambda will
1100	// be dependent, because there are template parameters in scope.
1101	CXXRecordDecl::LambdaDependencyKind LambdaDependencyKind =
1102	CXXRecordDecl::LDK_Unknown;
1103	if (CurScope->getTemplateParamParent() != nullptr) {
1104	LambdaDependencyKind = CXXRecordDecl::LDK_AlwaysDependent;
1105	} else if (Scope *P = CurScope->getParent()) {
1106	// Given a lambda defined inside a requires expression,
1107	//
1108	// struct S {
1109	// S(auto var) requires requires { [&] -> decltype(var) { }; }
1110	// {}
1111	// };
1112	//
1113	// The parameter var is not injected into the function Decl at the point of
1114	// parsing lambda. In such scenarios, perceiving it as dependent could
1115	// result in the constraint being evaluated, which matches what GCC does.
1116	while (P->getEntity() && P->getEntity()->isRequiresExprBody())
1117	P = P->getParent();
1118	if (P->isFunctionDeclarationScope() &&
1119	llvm::any_of(Range: P->decls(), P: [](Decl *D) {
1120	return isa<ParmVarDecl>(Val: D) &&
1121	cast<ParmVarDecl>(Val: D)->getType()->isTemplateTypeParmType();
1122	}))
1123	LambdaDependencyKind = CXXRecordDecl::LDK_AlwaysDependent;
1124	}
1125
1126	CXXRecordDecl *Class = createLambdaClosureType(
1127	IntroducerRange: Intro.Range, /*Info=*/nullptr, LambdaDependencyKind, CaptureDefault: Intro.Default);
1128	LSI->Lambda = Class;
1129
1130	CXXMethodDecl *Method = CreateLambdaCallOperator(IntroducerRange: Intro.Range, Class);
1131	LSI->CallOperator = Method;
1132	// Temporarily set the lexical declaration context to the current
1133	// context, so that the Scope stack matches the lexical nesting.
1134	Method->setLexicalDeclContext(CurContext);
1135
1136	PushDeclContext(S: CurScope, DC: Method);
1137
1138	bool ContainsUnexpandedParameterPack = false;
1139
1140	// Distinct capture names, for diagnostics.
1141	llvm::DenseMap<IdentifierInfo *, ValueDecl *> CaptureNames;
1142
1143	// Handle explicit captures.
1144	SourceLocation PrevCaptureLoc =
1145	Intro.Default == LCD_None ? Intro.Range.getBegin() : Intro.DefaultLoc;
1146	for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
1147	PrevCaptureLoc = C->Loc, ++C) {
1148	if (C->Kind == LCK_This || C->Kind == LCK_StarThis) {
1149	if (C->Kind == LCK_StarThis)
1150	Diag(Loc: C->Loc, DiagID: !getLangOpts().CPlusPlus17
1151	? diag::ext_star_this_lambda_capture_cxx17
1152	: diag::warn_cxx14_compat_star_this_lambda_capture);
1153
1154	// C++11 [expr.prim.lambda]p8:
1155	// An identifier or this shall not appear more than once in a
1156	// lambda-capture.
1157	if (LSI->isCXXThisCaptured()) {
1158	Diag(Loc: C->Loc, DiagID: diag::err_capture_more_than_once)
1159	<< "'this'" << SourceRange(LSI->getCXXThisCapture().getLocation())
1160	<< FixItHint::CreateRemoval(
1161	RemoveRange: SourceRange(getLocForEndOfToken(Loc: PrevCaptureLoc), C->Loc));
1162	continue;
1163	}
1164
1165	// C++20 [expr.prim.lambda]p8:
1166	// If a lambda-capture includes a capture-default that is =,
1167	// each simple-capture of that lambda-capture shall be of the form
1168	// "&identifier", "this", or "* this". [ Note: The form [&,this] is
1169	// redundant but accepted for compatibility with ISO C++14. --end note ]
1170	if (Intro.Default == LCD_ByCopy && C->Kind != LCK_StarThis)
1171	Diag(Loc: C->Loc, DiagID: !getLangOpts().CPlusPlus20
1172	? diag::ext_equals_this_lambda_capture_cxx20
1173	: diag::warn_cxx17_compat_equals_this_lambda_capture);
1174
1175	// C++11 [expr.prim.lambda]p12:
1176	// If this is captured by a local lambda expression, its nearest
1177	// enclosing function shall be a non-static member function.
1178	QualType ThisCaptureType = getCurrentThisType();
1179	if (ThisCaptureType.isNull()) {
1180	Diag(Loc: C->Loc, DiagID: diag::err_this_capture) << true;
1181	continue;
1182	}
1183
1184	CheckCXXThisCapture(Loc: C->Loc, /*Explicit=*/true, /*BuildAndDiagnose*/ true,
1185	/*FunctionScopeIndexToStopAtPtr*/ FunctionScopeIndexToStopAt: nullptr,
1186	ByCopy: C->Kind == LCK_StarThis);
1187	if (!LSI->Captures.empty())
1188	LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
1189	continue;
1190	}
1191
1192	assert(C->Id && "missing identifier for capture");
1193
1194	if (C->Init.isInvalid())
1195	continue;
1196
1197	ValueDecl *Var = nullptr;
1198	if (C->Init.isUsable()) {
1199	Diag(Loc: C->Loc, DiagID: getLangOpts().CPlusPlus14
1200	? diag::warn_cxx11_compat_init_capture
1201	: diag::ext_init_capture);
1202
1203	// If the initializer expression is usable, but the InitCaptureType
1204	// is not, then an error has occurred - so ignore the capture for now.
1205	// for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
1206	// FIXME: we should create the init capture variable and mark it invalid
1207	// in this case.
1208	if (C->InitCaptureType.get().isNull())
1209	continue;
1210
1211	if (C->Init.get()->containsUnexpandedParameterPack() &&
1212	!C->InitCaptureType.get()->getAs<PackExpansionType>())
1213	DiagnoseUnexpandedParameterPack(E: C->Init.get(), UPPC: UPPC_Initializer);
1214
1215	unsigned InitStyle;
1216	switch (C->InitKind) {
1217	case LambdaCaptureInitKind::NoInit:
1218	llvm_unreachable("not an init-capture?");
1219	case LambdaCaptureInitKind::CopyInit:
1220	InitStyle = VarDecl::CInit;
1221	break;
1222	case LambdaCaptureInitKind::DirectInit:
1223	InitStyle = VarDecl::CallInit;
1224	break;
1225	case LambdaCaptureInitKind::ListInit:
1226	InitStyle = VarDecl::ListInit;
1227	break;
1228	}
1229	Var = createLambdaInitCaptureVarDecl(Loc: C->Loc, InitCaptureType: C->InitCaptureType.get(),
1230	EllipsisLoc: C->EllipsisLoc, Id: C->Id, InitStyle,
1231	Init: C->Init.get(), DeclCtx: Method);
1232	assert(Var && "createLambdaInitCaptureVarDecl returned a null VarDecl?");
1233	if (auto *V = dyn_cast<VarDecl>(Val: Var))
1234	CheckShadow(S: CurrentScope, D: V);
1235	PushOnScopeChains(D: Var, S: CurrentScope, AddToContext: false);
1236	} else {
1237	assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
1238	"init capture has valid but null init?");
1239
1240	// C++11 [expr.prim.lambda]p8:
1241	// If a lambda-capture includes a capture-default that is &, the
1242	// identifiers in the lambda-capture shall not be preceded by &.
1243	// If a lambda-capture includes a capture-default that is =, [...]
1244	// each identifier it contains shall be preceded by &.
1245	if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
1246	Diag(Loc: C->Loc, DiagID: diag::err_reference_capture_with_reference_default)
1247	<< FixItHint::CreateRemoval(
1248	RemoveRange: SourceRange(getLocForEndOfToken(Loc: PrevCaptureLoc), C->Loc));
1249	continue;
1250	} else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
1251	Diag(Loc: C->Loc, DiagID: diag::err_copy_capture_with_copy_default)
1252	<< FixItHint::CreateRemoval(
1253	RemoveRange: SourceRange(getLocForEndOfToken(Loc: PrevCaptureLoc), C->Loc));
1254	continue;
1255	}
1256
1257	// C++11 [expr.prim.lambda]p10:
1258	// The identifiers in a capture-list are looked up using the usual
1259	// rules for unqualified name lookup (3.4.1)
1260	DeclarationNameInfo Name(C->Id, C->Loc);
1261	LookupResult R(*this, Name, LookupOrdinaryName);
1262	LookupName(R, S: CurScope);
1263	if (R.isAmbiguous())
1264	continue;
1265	if (R.empty()) {
1266	// FIXME: Disable corrections that would add qualification?
1267	CXXScopeSpec ScopeSpec;
1268	DeclFilterCCC<VarDecl> Validator{};
1269	if (DiagnoseEmptyLookup(S: CurScope, SS&: ScopeSpec, R, CCC&: Validator))
1270	continue;
1271	}
1272
1273	if (auto *BD = R.getAsSingle<BindingDecl>())
1274	Var = BD;
1275	else if (R.getAsSingle<FieldDecl>()) {
1276	Diag(Loc: C->Loc, DiagID: diag::err_capture_class_member_does_not_name_variable)
1277	<< C->Id;
1278	continue;
1279	} else
1280	Var = R.getAsSingle<VarDecl>();
1281	if (Var && DiagnoseUseOfDecl(D: Var, Locs: C->Loc))
1282	continue;
1283	}
1284
1285	// C++11 [expr.prim.lambda]p10:
1286	// [...] each such lookup shall find a variable with automatic storage
1287	// duration declared in the reaching scope of the local lambda expression.
1288	// Note that the 'reaching scope' check happens in tryCaptureVariable().
1289	if (!Var) {
1290	Diag(Loc: C->Loc, DiagID: diag::err_capture_does_not_name_variable) << C->Id;
1291	continue;
1292	}
1293
1294	// C++11 [expr.prim.lambda]p8:
1295	// An identifier or this shall not appear more than once in a
1296	// lambda-capture.
1297	if (auto [It, Inserted] = CaptureNames.insert(KV: std::pair{C->Id, Var});
1298	!Inserted) {
1299	if (C->InitKind == LambdaCaptureInitKind::NoInit &&
1300	!Var->isInitCapture()) {
1301	Diag(Loc: C->Loc, DiagID: diag::err_capture_more_than_once)
1302	<< C->Id << It->second->getBeginLoc()
1303	<< FixItHint::CreateRemoval(
1304	RemoveRange: SourceRange(getLocForEndOfToken(Loc: PrevCaptureLoc), C->Loc));
1305	Var->setInvalidDecl();
1306	} else if (Var && Var->isPlaceholderVar(LangOpts: getLangOpts())) {
1307	DiagPlaceholderVariableDefinition(Loc: C->Loc);
1308	} else {
1309	// Previous capture captured something different (one or both was
1310	// an init-capture): no fixit.
1311	Diag(Loc: C->Loc, DiagID: diag::err_capture_more_than_once) << C->Id;
1312	continue;
1313	}
1314	}
1315
1316	// Ignore invalid decls; they'll just confuse the code later.
1317	if (Var->isInvalidDecl())
1318	continue;
1319
1320	VarDecl *Underlying = Var->getPotentiallyDecomposedVarDecl();
1321
1322	if (!Underlying->hasLocalStorage()) {
1323	Diag(Loc: C->Loc, DiagID: diag::err_capture_non_automatic_variable) << C->Id;
1324	Diag(Loc: Var->getLocation(), DiagID: diag::note_previous_decl) << C->Id;
1325	continue;
1326	}
1327
1328	// C++11 [expr.prim.lambda]p23:
1329	// A capture followed by an ellipsis is a pack expansion (14.5.3).
1330	SourceLocation EllipsisLoc;
1331	if (C->EllipsisLoc.isValid()) {
1332	if (Var->isParameterPack()) {
1333	EllipsisLoc = C->EllipsisLoc;
1334	} else {
1335	Diag(Loc: C->EllipsisLoc, DiagID: diag::err_pack_expansion_without_parameter_packs)
1336	<< (C->Init.isUsable() ? C->Init.get()->getSourceRange()
1337	: SourceRange(C->Loc));
1338
1339	// Just ignore the ellipsis.
1340	}
1341	} else if (Var->isParameterPack()) {
1342	ContainsUnexpandedParameterPack = true;
1343	}
1344
1345	if (C->Init.isUsable()) {
1346	addInitCapture(LSI, Var: cast<VarDecl>(Val: Var), ByRef: C->Kind == LCK_ByRef);
1347	} else {
1348	TryCaptureKind Kind = C->Kind == LCK_ByRef
1349	? TryCaptureKind::ExplicitByRef
1350	: TryCaptureKind::ExplicitByVal;
1351	tryCaptureVariable(Var, Loc: C->Loc, Kind, EllipsisLoc);
1352	}
1353	if (!LSI->Captures.empty())
1354	LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
1355	}
1356	finishLambdaExplicitCaptures(LSI);
1357	LSI->ContainsUnexpandedParameterPack |= ContainsUnexpandedParameterPack;
1358	PopDeclContext();
1359	}
1360
1361	void Sema::ActOnLambdaClosureQualifiers(LambdaIntroducer &Intro,
1362	SourceLocation MutableLoc) {
1363
1364	LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(S&: *this);
1365	LSI->Mutable = MutableLoc.isValid();
1366	ContextRAII Context(*this, LSI->CallOperator, /*NewThisContext*/ false);
1367
1368	// C++11 [expr.prim.lambda]p9:
1369	// A lambda-expression whose smallest enclosing scope is a block scope is a
1370	// local lambda expression; any other lambda expression shall not have a
1371	// capture-default or simple-capture in its lambda-introducer.
1372	//
1373	// For simple-captures, this is covered by the check below that any named
1374	// entity is a variable that can be captured.
1375	//
1376	// For DR1632, we also allow a capture-default in any context where we can
1377	// odr-use 'this' (in particular, in a default initializer for a non-static
1378	// data member).
1379	if (Intro.Default != LCD_None &&
1380	!LSI->Lambda->getParent()->isFunctionOrMethod() &&
1381	(getCurrentThisType().isNull() ||
1382	CheckCXXThisCapture(Loc: SourceLocation(), /*Explicit=*/true,
1383	/*BuildAndDiagnose=*/false)))
1384	Diag(Loc: Intro.DefaultLoc, DiagID: diag::err_capture_default_non_local);
1385	}
1386
1387	void Sema::ActOnLambdaClosureParameters(
1388	Scope *LambdaScope, MutableArrayRef<DeclaratorChunk::ParamInfo> Params) {
1389	LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(S&: *this);
1390	PushDeclContext(S: LambdaScope, DC: LSI->CallOperator);
1391
1392	for (const DeclaratorChunk::ParamInfo &P : Params) {
1393	auto *Param = cast<ParmVarDecl>(Val: P.Param);
1394	Param->setOwningFunction(LSI->CallOperator);
1395	if (Param->getIdentifier())
1396	PushOnScopeChains(D: Param, S: LambdaScope, AddToContext: false);
1397	}
1398
1399	// After the parameter list, we may parse a noexcept/requires/trailing return
1400	// type which need to know whether the call operator constiture a dependent
1401	// context, so we need to setup the FunctionTemplateDecl of generic lambdas
1402	// now.
1403	TemplateParameterList *TemplateParams =
1404	getGenericLambdaTemplateParameterList(LSI, SemaRef&: *this);
1405	if (TemplateParams) {
1406	AddTemplateParametersToLambdaCallOperator(CallOperator: LSI->CallOperator, Class: LSI->Lambda,
1407	TemplateParams);
1408	LSI->Lambda->setLambdaIsGeneric(true);
1409	LSI->ContainsUnexpandedParameterPack |=
1410	TemplateParams->containsUnexpandedParameterPack();
1411	}
1412	LSI->AfterParameterList = true;
1413	}
1414
1415	void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
1416	Declarator &ParamInfo,
1417	const DeclSpec &DS) {
1418
1419	LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(S&: *this);
1420	LSI->CallOperator->setConstexprKind(DS.getConstexprSpecifier());
1421
1422	SmallVector<ParmVarDecl *, 8> Params;
1423	bool ExplicitResultType;
1424
1425	SourceLocation TypeLoc, CallOperatorLoc;
1426	if (ParamInfo.getNumTypeObjects() == 0) {
1427	CallOperatorLoc = TypeLoc = Intro.Range.getEnd();
1428	} else {
1429	unsigned Index;
1430	ParamInfo.isFunctionDeclarator(idx&: Index);
1431	const auto &Object = ParamInfo.getTypeObject(i: Index);
1432	TypeLoc =
1433	Object.Loc.isValid() ? Object.Loc : ParamInfo.getSourceRange().getEnd();
1434	CallOperatorLoc = ParamInfo.getSourceRange().getEnd();
1435	}
1436
1437	CXXRecordDecl *Class = LSI->Lambda;
1438	CXXMethodDecl *Method = LSI->CallOperator;
1439
1440	TypeSourceInfo *MethodTyInfo = getLambdaType(
1441	S&: *this, Intro, ParamInfo, CurScope: getCurScope(), Loc: TypeLoc, ExplicitResultType);
1442
1443	LSI->ExplicitParams = ParamInfo.getNumTypeObjects() != 0;
1444
1445	if (ParamInfo.isFunctionDeclarator() != 0 &&
1446	!FTIHasSingleVoidParameter(FTI: ParamInfo.getFunctionTypeInfo())) {
1447	const auto &FTI = ParamInfo.getFunctionTypeInfo();
1448	Params.reserve(N: Params.size());
1449	for (unsigned I = 0; I < FTI.NumParams; ++I) {
1450	auto *Param = cast<ParmVarDecl>(Val: FTI.Params[I].Param);
1451	Param->setScopeInfo(scopeDepth: 0, parameterIndex: Params.size());
1452	Params.push_back(Elt: Param);
1453	}
1454	}
1455
1456	bool IsLambdaStatic =
1457	ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static;
1458
1459	CompleteLambdaCallOperator(
1460	Method, LambdaLoc: Intro.Range.getBegin(), CallOperatorLoc,
1461	TrailingRequiresClause: AssociatedConstraint(ParamInfo.getTrailingRequiresClause()), MethodTyInfo,
1462	ConstexprKind: ParamInfo.getDeclSpec().getConstexprSpecifier(),
1463	SC: IsLambdaStatic ? SC_Static : SC_None, Params, HasExplicitResultType: ExplicitResultType);
1464
1465	CheckCXXDefaultArguments(FD: Method);
1466
1467	// This represents the function body for the lambda function, check if we
1468	// have to apply optnone due to a pragma.
1469	AddRangeBasedOptnone(FD: Method);
1470
1471	// code_seg attribute on lambda apply to the method.
1472	if (Attr *A = getImplicitCodeSegOrSectionAttrForFunction(
1473	FD: Method, /*IsDefinition=*/true))
1474	Method->addAttr(A);
1475
1476	// Attributes on the lambda apply to the method.
1477	ProcessDeclAttributes(S: CurScope, D: Method, PD: ParamInfo);
1478
1479	if (Context.getTargetInfo().getTriple().isAArch64())
1480	ARM().CheckSMEFunctionDefAttributes(FD: Method);
1481
1482	// CUDA lambdas get implicit host and device attributes.
1483	if (getLangOpts().CUDA)
1484	CUDA().SetLambdaAttrs(Method);
1485
1486	// OpenMP lambdas might get assumumption attributes.
1487	if (LangOpts.OpenMP)
1488	OpenMP().ActOnFinishedFunctionDefinitionInOpenMPAssumeScope(D: Method);
1489
1490	handleLambdaNumbering(Class, Method);
1491
1492	for (auto &&C : LSI->Captures) {
1493	if (!C.isVariableCapture())
1494	continue;
1495	ValueDecl *Var = C.getVariable();
1496	if (Var && Var->isInitCapture()) {
1497	PushOnScopeChains(D: Var, S: CurScope, AddToContext: false);
1498	}
1499	}
1500
1501	auto CheckRedefinition = [&](ParmVarDecl *Param) {
1502	for (const auto &Capture : Intro.Captures) {
1503	if (Capture.Id == Param->getIdentifier()) {
1504	Diag(Loc: Param->getLocation(), DiagID: diag::err_parameter_shadow_capture);
1505	Diag(Loc: Capture.Loc, DiagID: diag::note_var_explicitly_captured_here)
1506	<< Capture.Id << true;
1507	return false;
1508	}
1509	}
1510	return true;
1511	};
1512
1513	for (ParmVarDecl *P : Params) {
1514	if (!P->getIdentifier())
1515	continue;
1516	if (CheckRedefinition(P))
1517	CheckShadow(S: CurScope, D: P);
1518	PushOnScopeChains(D: P, S: CurScope);
1519	}
1520
1521	// C++23 [expr.prim.lambda.capture]p5:
1522	// If an identifier in a capture appears as the declarator-id of a parameter
1523	// of the lambda-declarator's parameter-declaration-clause or as the name of a
1524	// template parameter of the lambda-expression's template-parameter-list, the
1525	// program is ill-formed.
1526	TemplateParameterList *TemplateParams =
1527	getGenericLambdaTemplateParameterList(LSI, SemaRef&: *this);
1528	if (TemplateParams) {
1529	for (const auto *TP : TemplateParams->asArray()) {
1530	if (!TP->getIdentifier())
1531	continue;
1532	for (const auto &Capture : Intro.Captures) {
1533	if (Capture.Id == TP->getIdentifier()) {
1534	Diag(Loc: Capture.Loc, DiagID: diag::err_template_param_shadow) << Capture.Id;
1535	NoteTemplateParameterLocation(Decl: *TP);
1536	}
1537	}
1538	}
1539	}
1540
1541	// C++20: dcl.decl.general p4:
1542	// The optional requires-clause ([temp.pre]) in an init-declarator or
1543	// member-declarator shall be present only if the declarator declares a
1544	// templated function ([dcl.fct]).
1545	if (const AssociatedConstraint &TRC = Method->getTrailingRequiresClause()) {
1546	// [temp.pre]/8:
1547	// An entity is templated if it is
1548	// - a template,
1549	// - an entity defined ([basic.def]) or created ([class.temporary]) in a
1550	// templated entity,
1551	// - a member of a templated entity,
1552	// - an enumerator for an enumeration that is a templated entity, or
1553	// - the closure type of a lambda-expression ([expr.prim.lambda.closure])
1554	// appearing in the declaration of a templated entity. [Note 6: A local
1555	// class, a local or block variable, or a friend function defined in a
1556	// templated entity is a templated entity. — end note]
1557	//
1558	// A templated function is a function template or a function that is
1559	// templated. A templated class is a class template or a class that is
1560	// templated. A templated variable is a variable template or a variable
1561	// that is templated.
1562
1563	// Note: we only have to check if this is defined in a template entity, OR
1564	// if we are a template, since the rest don't apply. The requires clause
1565	// applies to the call operator, which we already know is a member function,
1566	// AND defined.
1567	if (!Method->getDescribedFunctionTemplate() && !Method->isTemplated()) {
1568	Diag(Loc: TRC.ConstraintExpr->getBeginLoc(),
1569	DiagID: diag::err_constrained_non_templated_function);
1570	}
1571	}
1572
1573	// Enter a new evaluation context to insulate the lambda from any
1574	// cleanups from the enclosing full-expression.
1575	PushExpressionEvaluationContextForFunction(
1576	NewContext: ExpressionEvaluationContext::PotentiallyEvaluated, FD: LSI->CallOperator);
1577	}
1578
1579	void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
1580	bool IsInstantiation) {
1581	LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(Val: FunctionScopes.back());
1582
1583	// Leave the expression-evaluation context.
1584	DiscardCleanupsInEvaluationContext();
1585	PopExpressionEvaluationContext();
1586
1587	// Leave the context of the lambda.
1588	if (!IsInstantiation)
1589	PopDeclContext();
1590
1591	// Finalize the lambda.
1592	CXXRecordDecl *Class = LSI->Lambda;
1593	Class->setInvalidDecl();
1594	SmallVector<Decl*, 4> Fields(Class->fields());
1595	ActOnFields(S: nullptr, RecLoc: Class->getLocation(), TagDecl: Class, Fields, LBrac: SourceLocation(),
1596	RBrac: SourceLocation(), AttrList: ParsedAttributesView());
1597	CheckCompletedCXXClass(S: nullptr, Record: Class);
1598
1599	PopFunctionScopeInfo();
1600	}
1601
1602	template <typename Func>
1603	static void repeatForLambdaConversionFunctionCallingConvs(
1604	Sema &S, const FunctionProtoType &CallOpProto, Func F) {
1605	CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
1606	IsVariadic: CallOpProto.isVariadic(), /*IsCXXMethod=*/false);
1607	CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
1608	IsVariadic: CallOpProto.isVariadic(), /*IsCXXMethod=*/true);
1609	CallingConv CallOpCC = CallOpProto.getCallConv();
1610
1611	/// Implement emitting a version of the operator for many of the calling
1612	/// conventions for MSVC, as described here:
1613	/// https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623.
1614	/// Experimentally, we determined that cdecl, stdcall, fastcall, and
1615	/// vectorcall are generated by MSVC when it is supported by the target.
1616	/// Additionally, we are ensuring that the default-free/default-member and
1617	/// call-operator calling convention are generated as well.
1618	/// NOTE: We intentionally generate a 'thiscall' on Win32 implicitly from the
1619	/// 'member default', despite MSVC not doing so. We do this in order to ensure
1620	/// that someone who intentionally places 'thiscall' on the lambda call
1621	/// operator will still get that overload, since we don't have the a way of
1622	/// detecting the attribute by the time we get here.
1623	if (S.getLangOpts().MSVCCompat) {
1624	CallingConv Convs[] = {
1625	CC_C, CC_X86StdCall, CC_X86FastCall, CC_X86VectorCall,
1626	DefaultFree, DefaultMember, CallOpCC};
1627	llvm::sort(C&: Convs);
1628	llvm::iterator_range<CallingConv *> Range(std::begin(arr&: Convs),
1629	llvm::unique(R&: Convs));
1630	const TargetInfo &TI = S.getASTContext().getTargetInfo();
1631
1632	for (CallingConv C : Range) {
1633	if (TI.checkCallingConvention(CC: C) == TargetInfo::CCCR_OK)
1634	F(C);
1635	}
1636	return;
1637	}
1638
1639	if (CallOpCC == DefaultMember && DefaultMember != DefaultFree) {
1640	F(DefaultFree);
1641	F(DefaultMember);
1642	} else {
1643	F(CallOpCC);
1644	}
1645	}
1646
1647	// Returns the 'standard' calling convention to be used for the lambda
1648	// conversion function, that is, the 'free' function calling convention unless
1649	// it is overridden by a non-default calling convention attribute.
1650	static CallingConv
1651	getLambdaConversionFunctionCallConv(Sema &S,
1652	const FunctionProtoType *CallOpProto) {
1653	CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
1654	IsVariadic: CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
1655	CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
1656	IsVariadic: CallOpProto->isVariadic(), /*IsCXXMethod=*/true);
1657	CallingConv CallOpCC = CallOpProto->getCallConv();
1658
1659	// If the call-operator hasn't been changed, return both the 'free' and
1660	// 'member' function calling convention.
1661	if (CallOpCC == DefaultMember && DefaultMember != DefaultFree)
1662	return DefaultFree;
1663	return CallOpCC;
1664	}
1665
1666	QualType Sema::getLambdaConversionFunctionResultType(
1667	const FunctionProtoType *CallOpProto, CallingConv CC) {
1668	const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
1669	CallOpProto->getExtProtoInfo();
1670	FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
1671	InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(cc: CC);
1672	InvokerExtInfo.TypeQuals = Qualifiers();
1673	assert(InvokerExtInfo.RefQualifier == RQ_None &&
1674	"Lambda's call operator should not have a reference qualifier");
1675	return Context.getFunctionType(ResultTy: CallOpProto->getReturnType(),
1676	Args: CallOpProto->getParamTypes(), EPI: InvokerExtInfo);
1677	}
1678
1679	/// Add a lambda's conversion to function pointer, as described in
1680	/// C++11 [expr.prim.lambda]p6.
1681	static void addFunctionPointerConversion(Sema &S, SourceRange IntroducerRange,
1682	CXXRecordDecl *Class,
1683	CXXMethodDecl *CallOperator,
1684	QualType InvokerFunctionTy) {
1685	// This conversion is explicitly disabled if the lambda's function has
1686	// pass_object_size attributes on any of its parameters.
1687	auto HasPassObjectSizeAttr = [](const ParmVarDecl *P) {
1688	return P->hasAttr<PassObjectSizeAttr>();
1689	};
1690	if (llvm::any_of(Range: CallOperator->parameters(), P: HasPassObjectSizeAttr))
1691	return;
1692
1693	// Add the conversion to function pointer.
1694	QualType PtrToFunctionTy = S.Context.getPointerType(T: InvokerFunctionTy);
1695
1696	// Create the type of the conversion function.
1697	FunctionProtoType::ExtProtoInfo ConvExtInfo(
1698	S.Context.getDefaultCallingConvention(
1699	/*IsVariadic=*/false, /*IsCXXMethod=*/true));
1700	// The conversion function is always const and noexcept.
1701	ConvExtInfo.TypeQuals = Qualifiers();
1702	ConvExtInfo.TypeQuals.addConst();
1703	ConvExtInfo.ExceptionSpec.Type = EST_BasicNoexcept;
1704	QualType ConvTy = S.Context.getFunctionType(ResultTy: PtrToFunctionTy, Args: {}, EPI: ConvExtInfo);
1705
1706	SourceLocation Loc = IntroducerRange.getBegin();
1707	DeclarationName ConversionName
1708	= S.Context.DeclarationNames.getCXXConversionFunctionName(
1709	Ty: S.Context.getCanonicalType(T: PtrToFunctionTy));
1710	// Construct a TypeSourceInfo for the conversion function, and wire
1711	// all the parameters appropriately for the FunctionProtoTypeLoc
1712	// so that everything works during transformation/instantiation of
1713	// generic lambdas.
1714	// The main reason for wiring up the parameters of the conversion
1715	// function with that of the call operator is so that constructs
1716	// like the following work:
1717	// auto L = [](auto b) { <-- 1
1718	// return [](auto a) -> decltype(a) { <-- 2
1719	// return a;
1720	// };
1721	// };
1722	// int (*fp)(int) = L(5);
1723	// Because the trailing return type can contain DeclRefExprs that refer
1724	// to the original call operator's variables, we hijack the call
1725	// operators ParmVarDecls below.
1726	TypeSourceInfo *ConvNamePtrToFunctionTSI =
1727	S.Context.getTrivialTypeSourceInfo(T: PtrToFunctionTy, Loc);
1728	DeclarationNameLoc ConvNameLoc =
1729	DeclarationNameLoc::makeNamedTypeLoc(TInfo: ConvNamePtrToFunctionTSI);
1730
1731	// The conversion function is a conversion to a pointer-to-function.
1732	TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(T: ConvTy, Loc);
1733	FunctionProtoTypeLoc ConvTL =
1734	ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
1735	// Get the result of the conversion function which is a pointer-to-function.
1736	PointerTypeLoc PtrToFunctionTL =
1737	ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
1738	// Do the same for the TypeSourceInfo that is used to name the conversion
1739	// operator.
1740	PointerTypeLoc ConvNamePtrToFunctionTL =
1741	ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
1742
1743	// Get the underlying function types that the conversion function will
1744	// be converting to (should match the type of the call operator).
1745	FunctionProtoTypeLoc CallOpConvTL =
1746	PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1747	FunctionProtoTypeLoc CallOpConvNameTL =
1748	ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1749
1750	// Wire up the FunctionProtoTypeLocs with the call operator's parameters.
1751	// These parameter's are essentially used to transform the name and
1752	// the type of the conversion operator. By using the same parameters
1753	// as the call operator's we don't have to fix any back references that
1754	// the trailing return type of the call operator's uses (such as
1755	// decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
1756	// - we can simply use the return type of the call operator, and
1757	// everything should work.
1758	SmallVector<ParmVarDecl *, 4> InvokerParams;
1759	for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1760	ParmVarDecl *From = CallOperator->getParamDecl(i: I);
1761
1762	InvokerParams.push_back(Elt: ParmVarDecl::Create(
1763	C&: S.Context,
1764	// Temporarily add to the TU. This is set to the invoker below.
1765	DC: S.Context.getTranslationUnitDecl(), StartLoc: From->getBeginLoc(),
1766	IdLoc: From->getLocation(), Id: From->getIdentifier(), T: From->getType(),
1767	TInfo: From->getTypeSourceInfo(), S: From->getStorageClass(),
1768	/*DefArg=*/nullptr));
1769	CallOpConvTL.setParam(i: I, VD: From);
1770	CallOpConvNameTL.setParam(i: I, VD: From);
1771	}
1772
1773	CXXConversionDecl *Conversion = CXXConversionDecl::Create(
1774	C&: S.Context, RD: Class, StartLoc: Loc,
1775	NameInfo: DeclarationNameInfo(ConversionName, Loc, ConvNameLoc), T: ConvTy, TInfo: ConvTSI,
1776	UsesFPIntrin: S.getCurFPFeatures().isFPConstrained(),
1777	/*isInline=*/true, ES: ExplicitSpecifier(),
1778	ConstexprKind: S.getLangOpts().CPlusPlus17 ? ConstexprSpecKind::Constexpr
1779	: ConstexprSpecKind::Unspecified,
1780	EndLocation: CallOperator->getBody()->getEndLoc());
1781	Conversion->setAccess(AS_public);
1782	Conversion->setImplicit(true);
1783
1784	// A non-generic lambda may still be a templated entity. We need to preserve
1785	// constraints when converting the lambda to a function pointer. See GH63181.
1786	if (const AssociatedConstraint &Requires =
1787	CallOperator->getTrailingRequiresClause())
1788	Conversion->setTrailingRequiresClause(Requires);
1789
1790	if (Class->isGenericLambda()) {
1791	// Create a template version of the conversion operator, using the template
1792	// parameter list of the function call operator.
1793	FunctionTemplateDecl *TemplateCallOperator =
1794	CallOperator->getDescribedFunctionTemplate();
1795	FunctionTemplateDecl *ConversionTemplate =
1796	FunctionTemplateDecl::Create(C&: S.Context, DC: Class,
1797	L: Loc, Name: ConversionName,
1798	Params: TemplateCallOperator->getTemplateParameters(),
1799	Decl: Conversion);
1800	ConversionTemplate->setAccess(AS_public);
1801	ConversionTemplate->setImplicit(true);
1802	Conversion->setDescribedFunctionTemplate(ConversionTemplate);
1803	Class->addDecl(D: ConversionTemplate);
1804	} else
1805	Class->addDecl(D: Conversion);
1806
1807	// If the lambda is not static, we need to add a static member
1808	// function that will be the result of the conversion with a
1809	// certain unique ID.
1810	// When it is static we just return the static call operator instead.
1811	if (CallOperator->isImplicitObjectMemberFunction()) {
1812	DeclarationName InvokerName =
1813	&S.Context.Idents.get(Name: getLambdaStaticInvokerName());
1814	// FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
1815	// we should get a prebuilt TrivialTypeSourceInfo from Context
1816	// using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
1817	// then rewire the parameters accordingly, by hoisting up the InvokeParams
1818	// loop below and then use its Params to set Invoke->setParams(...) below.
1819	// This would avoid the 'const' qualifier of the calloperator from
1820	// contaminating the type of the invoker, which is currently adjusted
1821	// in SemaTemplateDeduction.cpp:DeduceTemplateArguments. Fixing the
1822	// trailing return type of the invoker would require a visitor to rebuild
1823	// the trailing return type and adjusting all back DeclRefExpr's to refer
1824	// to the new static invoker parameters - not the call operator's.
1825	CXXMethodDecl *Invoke = CXXMethodDecl::Create(
1826	C&: S.Context, RD: Class, StartLoc: Loc, NameInfo: DeclarationNameInfo(InvokerName, Loc),
1827	T: InvokerFunctionTy, TInfo: CallOperator->getTypeSourceInfo(), SC: SC_Static,
1828	UsesFPIntrin: S.getCurFPFeatures().isFPConstrained(),
1829	/*isInline=*/true, ConstexprKind: CallOperator->getConstexprKind(),
1830	EndLocation: CallOperator->getBody()->getEndLoc());
1831	for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
1832	InvokerParams[I]->setOwningFunction(Invoke);
1833	Invoke->setParams(InvokerParams);
1834	Invoke->setAccess(AS_private);
1835	Invoke->setImplicit(true);
1836	if (Class->isGenericLambda()) {
1837	FunctionTemplateDecl *TemplateCallOperator =
1838	CallOperator->getDescribedFunctionTemplate();
1839	FunctionTemplateDecl *StaticInvokerTemplate =
1840	FunctionTemplateDecl::Create(
1841	C&: S.Context, DC: Class, L: Loc, Name: InvokerName,
1842	Params: TemplateCallOperator->getTemplateParameters(), Decl: Invoke);
1843	StaticInvokerTemplate->setAccess(AS_private);
1844	StaticInvokerTemplate->setImplicit(true);
1845	Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
1846	Class->addDecl(D: StaticInvokerTemplate);
1847	} else
1848	Class->addDecl(D: Invoke);
1849	}
1850	}
1851
1852	/// Add a lambda's conversion to function pointers, as described in
1853	/// C++11 [expr.prim.lambda]p6. Note that in most cases, this should emit only a
1854	/// single pointer conversion. In the event that the default calling convention
1855	/// for free and member functions is different, it will emit both conventions.
1856	static void addFunctionPointerConversions(Sema &S, SourceRange IntroducerRange,
1857	CXXRecordDecl *Class,
1858	CXXMethodDecl *CallOperator) {
1859	const FunctionProtoType *CallOpProto =
1860	CallOperator->getType()->castAs<FunctionProtoType>();
1861
1862	repeatForLambdaConversionFunctionCallingConvs(
1863	S, CallOpProto: *CallOpProto, F: [&](CallingConv CC) {
1864	QualType InvokerFunctionTy =
1865	S.getLambdaConversionFunctionResultType(CallOpProto, CC);
1866	addFunctionPointerConversion(S, IntroducerRange, Class, CallOperator,
1867	InvokerFunctionTy);
1868	});
1869	}
1870
1871	/// Add a lambda's conversion to block pointer.
1872	static void addBlockPointerConversion(Sema &S,
1873	SourceRange IntroducerRange,
1874	CXXRecordDecl *Class,
1875	CXXMethodDecl *CallOperator) {
1876	const FunctionProtoType *CallOpProto =
1877	CallOperator->getType()->castAs<FunctionProtoType>();
1878	QualType FunctionTy = S.getLambdaConversionFunctionResultType(
1879	CallOpProto, CC: getLambdaConversionFunctionCallConv(S, CallOpProto));
1880	QualType BlockPtrTy = S.Context.getBlockPointerType(T: FunctionTy);
1881
1882	FunctionProtoType::ExtProtoInfo ConversionEPI(
1883	S.Context.getDefaultCallingConvention(
1884	/*IsVariadic=*/false, /*IsCXXMethod=*/true));
1885	ConversionEPI.TypeQuals = Qualifiers();
1886	ConversionEPI.TypeQuals.addConst();
1887	QualType ConvTy = S.Context.getFunctionType(ResultTy: BlockPtrTy, Args: {}, EPI: ConversionEPI);
1888
1889	SourceLocation Loc = IntroducerRange.getBegin();
1890	DeclarationName Name
1891	= S.Context.DeclarationNames.getCXXConversionFunctionName(
1892	Ty: S.Context.getCanonicalType(T: BlockPtrTy));
1893	DeclarationNameLoc NameLoc = DeclarationNameLoc::makeNamedTypeLoc(
1894	TInfo: S.Context.getTrivialTypeSourceInfo(T: BlockPtrTy, Loc));
1895	CXXConversionDecl *Conversion = CXXConversionDecl::Create(
1896	C&: S.Context, RD: Class, StartLoc: Loc, NameInfo: DeclarationNameInfo(Name, Loc, NameLoc), T: ConvTy,
1897	TInfo: S.Context.getTrivialTypeSourceInfo(T: ConvTy, Loc),
1898	UsesFPIntrin: S.getCurFPFeatures().isFPConstrained(),
1899	/*isInline=*/true, ES: ExplicitSpecifier(), ConstexprKind: ConstexprSpecKind::Unspecified,
1900	EndLocation: CallOperator->getBody()->getEndLoc());
1901	Conversion->setAccess(AS_public);
1902	Conversion->setImplicit(true);
1903	Class->addDecl(D: Conversion);
1904	}
1905
1906	ExprResult Sema::BuildCaptureInit(const Capture &Cap,
1907	SourceLocation ImplicitCaptureLoc,
1908	bool IsOpenMPMapping) {
1909	// VLA captures don't have a stored initialization expression.
1910	if (Cap.isVLATypeCapture())
1911	return ExprResult();
1912
1913	// An init-capture is initialized directly from its stored initializer.
1914	if (Cap.isInitCapture())
1915	return cast<VarDecl>(Val: Cap.getVariable())->getInit();
1916
1917	// For anything else, build an initialization expression. For an implicit
1918	// capture, the capture notionally happens at the capture-default, so use
1919	// that location here.
1920	SourceLocation Loc =
1921	ImplicitCaptureLoc.isValid() ? ImplicitCaptureLoc : Cap.getLocation();
1922
1923	// C++11 [expr.prim.lambda]p21:
1924	// When the lambda-expression is evaluated, the entities that
1925	// are captured by copy are used to direct-initialize each
1926	// corresponding non-static data member of the resulting closure
1927	// object. (For array members, the array elements are
1928	// direct-initialized in increasing subscript order.) These
1929	// initializations are performed in the (unspecified) order in
1930	// which the non-static data members are declared.
1931
1932	// C++ [expr.prim.lambda]p12:
1933	// An entity captured by a lambda-expression is odr-used (3.2) in
1934	// the scope containing the lambda-expression.
1935	ExprResult Init;
1936	IdentifierInfo *Name = nullptr;
1937	if (Cap.isThisCapture()) {
1938	QualType ThisTy = getCurrentThisType();
1939	Expr *This = BuildCXXThisExpr(Loc, Type: ThisTy, IsImplicit: ImplicitCaptureLoc.isValid());
1940	if (Cap.isCopyCapture())
1941	Init = CreateBuiltinUnaryOp(OpLoc: Loc, Opc: UO_Deref, InputExpr: This);
1942	else
1943	Init = This;
1944	} else {
1945	assert(Cap.isVariableCapture() && "unknown kind of capture");
1946	ValueDecl *Var = Cap.getVariable();
1947	Name = Var->getIdentifier();
1948	Init = BuildDeclarationNameExpr(
1949	SS: CXXScopeSpec(), NameInfo: DeclarationNameInfo(Var->getDeclName(), Loc), D: Var);
1950	}
1951
1952	// In OpenMP, the capture kind doesn't actually describe how to capture:
1953	// variables are "mapped" onto the device in a process that does not formally
1954	// make a copy, even for a "copy capture".
1955	if (IsOpenMPMapping)
1956	return Init;
1957
1958	if (Init.isInvalid())
1959	return ExprError();
1960
1961	Expr *InitExpr = Init.get();
1962	InitializedEntity Entity = InitializedEntity::InitializeLambdaCapture(
1963	VarID: Name, FieldType: Cap.getCaptureType(), Loc);
1964	InitializationKind InitKind =
1965	InitializationKind::CreateDirect(InitLoc: Loc, LParenLoc: Loc, RParenLoc: Loc);
1966	InitializationSequence InitSeq(*this, Entity, InitKind, InitExpr);
1967	return InitSeq.Perform(S&: *this, Entity, Kind: InitKind, Args: InitExpr);
1968	}
1969
1970	ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body) {
1971	LambdaScopeInfo LSI = *cast<LambdaScopeInfo>(Val: FunctionScopes.back());
1972
1973	if (LSI.CallOperator->hasAttr<SYCLKernelEntryPointAttr>())
1974	SYCL().CheckSYCLEntryPointFunctionDecl(FD: LSI.CallOperator);
1975
1976	ActOnFinishFunctionBody(Decl: LSI.CallOperator, Body);
1977
1978	return BuildLambdaExpr(StartLoc, EndLoc: Body->getEndLoc(), LSI: &LSI);
1979	}
1980
1981	static LambdaCaptureDefault
1982	mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
1983	switch (ICS) {
1984	case CapturingScopeInfo::ImpCap_None:
1985	return LCD_None;
1986	case CapturingScopeInfo::ImpCap_LambdaByval:
1987	return LCD_ByCopy;
1988	case CapturingScopeInfo::ImpCap_CapturedRegion:
1989	case CapturingScopeInfo::ImpCap_LambdaByref:
1990	return LCD_ByRef;
1991	case CapturingScopeInfo::ImpCap_Block:
1992	llvm_unreachable("block capture in lambda");
1993	}
1994	llvm_unreachable("Unknown implicit capture style");
1995	}
1996
1997	bool Sema::CaptureHasSideEffects(const Capture &From) {
1998	if (From.isInitCapture()) {
1999	Expr *Init = cast<VarDecl>(Val: From.getVariable())->getInit();
2000	if (Init && Init->HasSideEffects(Ctx: Context))
2001	return true;
2002	}
2003
2004	if (!From.isCopyCapture())
2005	return false;
2006
2007	const QualType T = From.isThisCapture()
2008	? getCurrentThisType()->getPointeeType()
2009	: From.getCaptureType();
2010
2011	if (T.isVolatileQualified())
2012	return true;
2013
2014	const Type *BaseT = T->getBaseElementTypeUnsafe();
2015	if (const CXXRecordDecl *RD = BaseT->getAsCXXRecordDecl())
2016	return !RD->isCompleteDefinition() || !RD->hasTrivialCopyConstructor() ||
2017	!RD->hasTrivialDestructor();
2018
2019	return false;
2020	}
2021
2022	bool Sema::DiagnoseUnusedLambdaCapture(SourceRange CaptureRange,
2023	SourceRange FixItRange,
2024	const Capture &From) {
2025	if (CaptureHasSideEffects(From))
2026	return false;
2027
2028	if (From.isVLATypeCapture())
2029	return false;
2030
2031	// FIXME: maybe we should warn on these if we can find a sensible diagnostic
2032	// message
2033	if (From.isInitCapture() &&
2034	From.getVariable()->isPlaceholderVar(LangOpts: getLangOpts()))
2035	return false;
2036
2037	auto diag = Diag(Loc: From.getLocation(), DiagID: diag::warn_unused_lambda_capture);
2038	if (From.isThisCapture())
2039	diag << "'this'";
2040	else
2041	diag << From.getVariable();
2042	diag << From.isNonODRUsed();
2043	// If we were able to resolve the fixit range we'll create a fixit,
2044	// otherwise we just use the raw capture range for the diagnostic.
2045	if (FixItRange.isValid())
2046	diag << FixItHint::CreateRemoval(RemoveRange: FixItRange);
2047	else
2048	diag << CaptureRange;
2049	return true;
2050	}
2051
2052	/// Create a field within the lambda class or captured statement record for the
2053	/// given capture.
2054	FieldDecl *Sema::BuildCaptureField(RecordDecl *RD,
2055	const sema::Capture &Capture) {
2056	SourceLocation Loc = Capture.getLocation();
2057	QualType FieldType = Capture.getCaptureType();
2058
2059	TypeSourceInfo *TSI = nullptr;
2060	if (Capture.isVariableCapture()) {
2061	const auto *Var = dyn_cast_or_null<VarDecl>(Val: Capture.getVariable());
2062	if (Var && Var->isInitCapture())
2063	TSI = Var->getTypeSourceInfo();
2064	}
2065
2066	// FIXME: Should we really be doing this? A null TypeSourceInfo seems more
2067	// appropriate, at least for an implicit capture.
2068	if (!TSI)
2069	TSI = Context.getTrivialTypeSourceInfo(T: FieldType, Loc);
2070
2071	// Build the non-static data member.
2072	FieldDecl *Field =
2073	FieldDecl::Create(C: Context, DC: RD, /*StartLoc=*/Loc, /*IdLoc=*/Loc,
2074	/*Id=*/nullptr, T: FieldType, TInfo: TSI, /*BW=*/nullptr,
2075	/*Mutable=*/false, InitStyle: ICIS_NoInit);
2076	// If the variable being captured has an invalid type, mark the class as
2077	// invalid as well.
2078	if (!FieldType->isDependentType()) {
2079	if (RequireCompleteSizedType(Loc, T: FieldType,
2080	DiagID: diag::err_field_incomplete_or_sizeless)) {
2081	RD->setInvalidDecl();
2082	Field->setInvalidDecl();
2083	} else {
2084	NamedDecl *Def;
2085	FieldType->isIncompleteType(Def: &Def);
2086	if (Def && Def->isInvalidDecl()) {
2087	RD->setInvalidDecl();
2088	Field->setInvalidDecl();
2089	}
2090	}
2091	}
2092	Field->setImplicit(true);
2093	Field->setAccess(AS_private);
2094	RD->addDecl(D: Field);
2095
2096	if (Capture.isVLATypeCapture())
2097	Field->setCapturedVLAType(Capture.getCapturedVLAType());
2098
2099	return Field;
2100	}
2101
2102	static SourceRange
2103	ConstructFixItRangeForUnusedCapture(Sema &S, SourceRange CaptureRange,
2104	SourceLocation PrevCaptureLoc,
2105	bool CurHasPreviousCapture, bool IsLast) {
2106	if (!CaptureRange.isValid())
2107	return SourceRange();
2108
2109	auto GetTrailingEndLocation = [&](SourceLocation StartPoint) {
2110	SourceRange NextToken = S.getRangeForNextToken(
2111	Loc: StartPoint, /*IncludeMacros=*/false, /*IncludeComments=*/true);
2112	if (!NextToken.isValid())
2113	return SourceLocation();
2114	// Return the last location preceding the next token
2115	return NextToken.getBegin().getLocWithOffset(Offset: -1);
2116	};
2117
2118	if (!CurHasPreviousCapture && !IsLast) {
2119	// If there are no captures preceding this capture, remove the
2120	// trailing comma and anything up to the next token
2121	SourceRange CommaRange =
2122	S.getRangeForNextToken(Loc: CaptureRange.getEnd(), /*IncludeMacros=*/false,
2123	/*IncludeComments=*/false, ExpectedToken: tok::comma);
2124	SourceLocation FixItEnd = GetTrailingEndLocation(CommaRange.getBegin());
2125	return SourceRange(CaptureRange.getBegin(), FixItEnd);
2126	}
2127
2128	// Otherwise, remove the comma since the last used capture, and
2129	// anything up to the next token
2130	SourceLocation FixItStart = S.getLocForEndOfToken(Loc: PrevCaptureLoc);
2131	SourceLocation FixItEnd = GetTrailingEndLocation(CaptureRange.getEnd());
2132	return SourceRange(FixItStart, FixItEnd);
2133	}
2134
2135	ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
2136	LambdaScopeInfo *LSI) {
2137	// Collect information from the lambda scope.
2138	SmallVector<LambdaCapture, 4> Captures;
2139	SmallVector<Expr *, 4> CaptureInits;
2140	SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
2141	LambdaCaptureDefault CaptureDefault =
2142	mapImplicitCaptureStyle(ICS: LSI->ImpCaptureStyle);
2143	CXXRecordDecl *Class;
2144	CXXMethodDecl *CallOperator;
2145	SourceRange IntroducerRange;
2146	bool ExplicitParams;
2147	bool ExplicitResultType;
2148	CleanupInfo LambdaCleanup;
2149	bool ContainsUnexpandedParameterPack;
2150	bool IsGenericLambda;
2151	{
2152	CallOperator = LSI->CallOperator;
2153	Class = LSI->Lambda;
2154	IntroducerRange = LSI->IntroducerRange;
2155	ExplicitParams = LSI->ExplicitParams;
2156	ExplicitResultType = !LSI->HasImplicitReturnType;
2157	LambdaCleanup = LSI->Cleanup;
2158	ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
2159	IsGenericLambda = Class->isGenericLambda();
2160
2161	CallOperator->setLexicalDeclContext(Class);
2162	Decl *TemplateOrNonTemplateCallOperatorDecl =
2163	CallOperator->getDescribedFunctionTemplate()
2164	? CallOperator->getDescribedFunctionTemplate()
2165	: cast<Decl>(Val: CallOperator);
2166
2167	// FIXME: Is this really the best choice? Keeping the lexical decl context
2168	// set as CurContext seems more faithful to the source.
2169	TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
2170
2171	PopExpressionEvaluationContext();
2172
2173	// True if the current capture has a used capture or default before it.
2174	bool CurHasPreviousCapture = CaptureDefault != LCD_None;
2175	SourceLocation PrevCaptureLoc = CurHasPreviousCapture ?
2176	CaptureDefaultLoc : IntroducerRange.getBegin();
2177
2178	for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I) {
2179	const Capture &From = LSI->Captures[I];
2180
2181	if (From.isInvalid())
2182	return ExprError();
2183
2184	assert(!From.isBlockCapture() && "Cannot capture __block variables");
2185	bool IsImplicit = I >= LSI->NumExplicitCaptures;
2186	SourceLocation ImplicitCaptureLoc =
2187	IsImplicit ? CaptureDefaultLoc : SourceLocation();
2188
2189	// Use source ranges of explicit captures for fixits where available.
2190	SourceRange CaptureRange = LSI->ExplicitCaptureRanges[I];
2191
2192	// Warn about unused explicit captures.
2193	bool IsCaptureUsed = true;
2194	if (!CurContext->isDependentContext() && !IsImplicit &&
2195	!From.isODRUsed()) {
2196	// Initialized captures that are non-ODR used may not be eliminated.
2197	// FIXME: Where did the IsGenericLambda here come from?
2198	bool NonODRUsedInitCapture =
2199	IsGenericLambda && From.isNonODRUsed() && From.isInitCapture();
2200	if (!NonODRUsedInitCapture) {
2201	bool IsLast = (I + 1) == LSI->NumExplicitCaptures;
2202	SourceRange FixItRange = ConstructFixItRangeForUnusedCapture(
2203	S&: *this, CaptureRange, PrevCaptureLoc, CurHasPreviousCapture,
2204	IsLast);
2205	IsCaptureUsed =
2206	!DiagnoseUnusedLambdaCapture(CaptureRange, FixItRange, From);
2207	}
2208	}
2209
2210	if (CaptureRange.isValid()) {
2211	CurHasPreviousCapture |= IsCaptureUsed;
2212	PrevCaptureLoc = CaptureRange.getEnd();
2213	}
2214
2215	// Map the capture to our AST representation.
2216	LambdaCapture Capture = [&] {
2217	if (From.isThisCapture()) {
2218	// Capturing 'this' implicitly with a default of '[=]' is deprecated,
2219	// because it results in a reference capture. Don't warn prior to
2220	// C++2a; there's nothing that can be done about it before then.
2221	if (getLangOpts().CPlusPlus20 && IsImplicit &&
2222	CaptureDefault == LCD_ByCopy) {
2223	Diag(Loc: From.getLocation(), DiagID: diag::warn_deprecated_this_capture);
2224	Diag(Loc: CaptureDefaultLoc, DiagID: diag::note_deprecated_this_capture)
2225	<< FixItHint::CreateInsertion(
2226	InsertionLoc: getLocForEndOfToken(Loc: CaptureDefaultLoc), Code: ", this");
2227	}
2228	return LambdaCapture(From.getLocation(), IsImplicit,
2229	From.isCopyCapture() ? LCK_StarThis : LCK_This);
2230	} else if (From.isVLATypeCapture()) {
2231	return LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType);
2232	} else {
2233	assert(From.isVariableCapture() && "unknown kind of capture");
2234	ValueDecl *Var = From.getVariable();
2235	LambdaCaptureKind Kind =
2236	From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
2237	return LambdaCapture(From.getLocation(), IsImplicit, Kind, Var,
2238	From.getEllipsisLoc());
2239	}
2240	}();
2241
2242	// Form the initializer for the capture field.
2243	ExprResult Init = BuildCaptureInit(Cap: From, ImplicitCaptureLoc);
2244
2245	// FIXME: Skip this capture if the capture is not used, the initializer
2246	// has no side-effects, the type of the capture is trivial, and the
2247	// lambda is not externally visible.
2248
2249	// Add a FieldDecl for the capture and form its initializer.
2250	BuildCaptureField(RD: Class, Capture: From);
2251	Captures.push_back(Elt: Capture);
2252	CaptureInits.push_back(Elt: Init.get());
2253
2254	if (LangOpts.CUDA)
2255	CUDA().CheckLambdaCapture(D: CallOperator, Capture: From);
2256	}
2257
2258	Class->setCaptures(Context, Captures);
2259
2260	// C++11 [expr.prim.lambda]p6:
2261	// The closure type for a lambda-expression with no lambda-capture
2262	// has a public non-virtual non-explicit const conversion function
2263	// to pointer to function having the same parameter and return
2264	// types as the closure type's function call operator.
2265	if (Captures.empty() && CaptureDefault == LCD_None)
2266	addFunctionPointerConversions(S&: *this, IntroducerRange, Class,
2267	CallOperator);
2268
2269	// Objective-C++:
2270	// The closure type for a lambda-expression has a public non-virtual
2271	// non-explicit const conversion function to a block pointer having the
2272	// same parameter and return types as the closure type's function call
2273	// operator.
2274	// FIXME: Fix generic lambda to block conversions.
2275	if (getLangOpts().Blocks && getLangOpts().ObjC && !IsGenericLambda)
2276	addBlockPointerConversion(S&: *this, IntroducerRange, Class, CallOperator);
2277
2278	// Finalize the lambda class.
2279	SmallVector<Decl*, 4> Fields(Class->fields());
2280	ActOnFields(S: nullptr, RecLoc: Class->getLocation(), TagDecl: Class, Fields, LBrac: SourceLocation(),
2281	RBrac: SourceLocation(), AttrList: ParsedAttributesView());
2282	CheckCompletedCXXClass(S: nullptr, Record: Class);
2283	}
2284
2285	Cleanup.mergeFrom(Rhs: LambdaCleanup);
2286
2287	LambdaExpr *Lambda =
2288	LambdaExpr::Create(C: Context, Class, IntroducerRange, CaptureDefault,
2289	CaptureDefaultLoc, ExplicitParams, ExplicitResultType,
2290	CaptureInits, ClosingBrace: EndLoc, ContainsUnexpandedParameterPack);
2291
2292	// If the lambda expression's call operator is not explicitly marked constexpr
2293	// and is not dependent, analyze the call operator to infer
2294	// its constexpr-ness, suppressing diagnostics while doing so.
2295	if (getLangOpts().CPlusPlus17 && !CallOperator->isInvalidDecl() &&
2296	!CallOperator->isConstexpr() &&
2297	!isa<CoroutineBodyStmt>(Val: CallOperator->getBody()) &&
2298	!Class->isDependentContext()) {
2299	CallOperator->setConstexprKind(
2300	CheckConstexprFunctionDefinition(FD: CallOperator,
2301	Kind: CheckConstexprKind::CheckValid)
2302	? ConstexprSpecKind::Constexpr
2303	: ConstexprSpecKind::Unspecified);
2304	}
2305
2306	// Emit delayed shadowing warnings now that the full capture list is known.
2307	DiagnoseShadowingLambdaDecls(LSI);
2308
2309	if (!CurContext->isDependentContext()) {
2310	switch (ExprEvalContexts.back().Context) {
2311	// C++11 [expr.prim.lambda]p2:
2312	// A lambda-expression shall not appear in an unevaluated operand
2313	// (Clause 5).
2314	case ExpressionEvaluationContext::Unevaluated:
2315	case ExpressionEvaluationContext::UnevaluatedList:
2316	case ExpressionEvaluationContext::UnevaluatedAbstract:
2317	// C++1y [expr.const]p2:
2318	// A conditional-expression e is a core constant expression unless the
2319	// evaluation of e, following the rules of the abstract machine, would
2320	// evaluate [...] a lambda-expression.
2321	//
2322	// This is technically incorrect, there are some constant evaluated contexts
2323	// where this should be allowed. We should probably fix this when DR1607 is
2324	// ratified, it lays out the exact set of conditions where we shouldn't
2325	// allow a lambda-expression.
2326	case ExpressionEvaluationContext::ConstantEvaluated:
2327	case ExpressionEvaluationContext::ImmediateFunctionContext:
2328	// We don't actually diagnose this case immediately, because we
2329	// could be within a context where we might find out later that
2330	// the expression is potentially evaluated (e.g., for typeid).
2331	ExprEvalContexts.back().Lambdas.push_back(Elt: Lambda);
2332	break;
2333
2334	case ExpressionEvaluationContext::DiscardedStatement:
2335	case ExpressionEvaluationContext::PotentiallyEvaluated:
2336	case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
2337	break;
2338	}
2339	maybeAddDeclWithEffects(D: LSI->CallOperator);
2340	}
2341
2342	return MaybeBindToTemporary(E: Lambda);
2343	}
2344
2345	ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
2346	SourceLocation ConvLocation,
2347	CXXConversionDecl *Conv,
2348	Expr *Src) {
2349	// Make sure that the lambda call operator is marked used.
2350	CXXRecordDecl *Lambda = Conv->getParent();
2351	CXXMethodDecl *CallOperator
2352	= cast<CXXMethodDecl>(
2353	Val: Lambda->lookup(
2354	Name: Context.DeclarationNames.getCXXOperatorName(Op: OO_Call)).front());
2355	CallOperator->setReferenced();
2356	CallOperator->markUsed(C&: Context);
2357
2358	ExprResult Init = PerformCopyInitialization(
2359	Entity: InitializedEntity::InitializeLambdaToBlock(BlockVarLoc: ConvLocation, Type: Src->getType()),
2360	EqualLoc: CurrentLocation, Init: Src);
2361	if (!Init.isInvalid())
2362	Init = ActOnFinishFullExpr(Expr: Init.get(), /*DiscardedValue*/ false);
2363
2364	if (Init.isInvalid())
2365	return ExprError();
2366
2367	// Create the new block to be returned.
2368	BlockDecl *Block = BlockDecl::Create(C&: Context, DC: CurContext, L: ConvLocation);
2369
2370	// Set the type information.
2371	Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
2372	Block->setIsVariadic(CallOperator->isVariadic());
2373	Block->setBlockMissingReturnType(false);
2374
2375	// Add parameters.
2376	SmallVector<ParmVarDecl *, 4> BlockParams;
2377	for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
2378	ParmVarDecl *From = CallOperator->getParamDecl(i: I);
2379	BlockParams.push_back(Elt: ParmVarDecl::Create(
2380	C&: Context, DC: Block, StartLoc: From->getBeginLoc(), IdLoc: From->getLocation(),
2381	Id: From->getIdentifier(), T: From->getType(), TInfo: From->getTypeSourceInfo(),
2382	S: From->getStorageClass(),
2383	/*DefArg=*/nullptr));
2384	}
2385	Block->setParams(BlockParams);
2386
2387	Block->setIsConversionFromLambda(true);
2388
2389	// Add capture. The capture uses a fake variable, which doesn't correspond
2390	// to any actual memory location. However, the initializer copy-initializes
2391	// the lambda object.
2392	TypeSourceInfo *CapVarTSI =
2393	Context.getTrivialTypeSourceInfo(T: Src->getType());
2394	VarDecl *CapVar = VarDecl::Create(C&: Context, DC: Block, StartLoc: ConvLocation,
2395	IdLoc: ConvLocation, Id: nullptr,
2396	T: Src->getType(), TInfo: CapVarTSI,
2397	S: SC_None);
2398	BlockDecl::Capture Capture(/*variable=*/CapVar, /*byRef=*/false,
2399	/*nested=*/false, /*copy=*/Init.get());
2400	Block->setCaptures(Context, Captures: Capture, /*CapturesCXXThis=*/false);
2401
2402	// Add a fake function body to the block. IR generation is responsible
2403	// for filling in the actual body, which cannot be expressed as an AST.
2404	Block->setBody(new (Context) CompoundStmt(ConvLocation));
2405
2406	// Create the block literal expression.
2407	// TODO: Do we ever get here if we have unexpanded packs in the lambda???
2408	Expr *BuildBlock =
2409	new (Context) BlockExpr(Block, Conv->getConversionType(),
2410	/*ContainsUnexpandedParameterPack=*/false);
2411	ExprCleanupObjects.push_back(Elt: Block);
2412	Cleanup.setExprNeedsCleanups(true);
2413
2414	return BuildBlock;
2415	}
2416
2417	static FunctionDecl *getPatternFunctionDecl(FunctionDecl *FD) {
2418	if (FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization) {
2419	while (FD->getInstantiatedFromMemberFunction())
2420	FD = FD->getInstantiatedFromMemberFunction();
2421	return FD;
2422	}
2423
2424	if (FD->getTemplatedKind() == FunctionDecl::TK_DependentNonTemplate)
2425	return FD->getInstantiatedFromDecl();
2426
2427	FunctionTemplateDecl *FTD = FD->getPrimaryTemplate();
2428	if (!FTD)
2429	return nullptr;
2430
2431	while (FTD->getInstantiatedFromMemberTemplate())
2432	FTD = FTD->getInstantiatedFromMemberTemplate();
2433
2434	return FTD->getTemplatedDecl();
2435	}
2436
2437	bool Sema::addInstantiatedCapturesToScope(
2438	FunctionDecl *Function, const FunctionDecl *PatternDecl,
2439	LocalInstantiationScope &Scope,
2440	const MultiLevelTemplateArgumentList &TemplateArgs) {
2441	const auto *LambdaClass = cast<CXXMethodDecl>(Val: Function)->getParent();
2442	const auto *LambdaPattern = cast<CXXMethodDecl>(Val: PatternDecl)->getParent();
2443
2444	unsigned Instantiated = 0;
2445
2446	// FIXME: This is a workaround for not having deferred lambda body
2447	// instantiation.
2448	// When transforming a lambda's body, if we encounter another call to a
2449	// nested lambda that contains a constraint expression, we add all of the
2450	// outer lambda's instantiated captures to the current instantiation scope to
2451	// facilitate constraint evaluation. However, these captures don't appear in
2452	// the CXXRecordDecl until after the lambda expression is rebuilt, so we
2453	// pull them out from the corresponding LSI.
2454	LambdaScopeInfo *InstantiatingScope = nullptr;
2455	if (LambdaPattern->capture_size() && !LambdaClass->capture_size()) {
2456	for (FunctionScopeInfo *Scope : llvm::reverse(C&: FunctionScopes)) {
2457	auto *LSI = dyn_cast<LambdaScopeInfo>(Val: Scope);
2458	if (!LSI || getPatternFunctionDecl(FD: LSI->CallOperator) != PatternDecl)
2459	continue;
2460	InstantiatingScope = LSI;
2461	break;
2462	}
2463	assert(InstantiatingScope);
2464	}
2465
2466	auto AddSingleCapture = [&](const ValueDecl *CapturedPattern,
2467	unsigned Index) {
2468	ValueDecl *CapturedVar =
2469	InstantiatingScope ? InstantiatingScope->Captures[Index].getVariable()
2470	: LambdaClass->getCapture(I: Index)->getCapturedVar();
2471	assert(CapturedVar->isInitCapture());
2472	Scope.InstantiatedLocal(D: CapturedPattern, Inst: CapturedVar);
2473	};
2474
2475	for (const LambdaCapture &CapturePattern : LambdaPattern->captures()) {
2476	if (!CapturePattern.capturesVariable()) {
2477	Instantiated++;
2478	continue;
2479	}
2480	ValueDecl *CapturedPattern = CapturePattern.getCapturedVar();
2481
2482	if (!CapturedPattern->isInitCapture()) {
2483	Instantiated++;
2484	continue;
2485	}
2486
2487	if (!CapturedPattern->isParameterPack()) {
2488	AddSingleCapture(CapturedPattern, Instantiated++);
2489	} else {
2490	Scope.MakeInstantiatedLocalArgPack(D: CapturedPattern);
2491	SmallVector<UnexpandedParameterPack, 2> Unexpanded;
2492	SemaRef.collectUnexpandedParameterPacks(
2493	E: dyn_cast<VarDecl>(Val: CapturedPattern)->getInit(), Unexpanded);
2494	auto NumArgumentsInExpansion =
2495	getNumArgumentsInExpansionFromUnexpanded(Unexpanded, TemplateArgs);
2496	if (!NumArgumentsInExpansion)
2497	continue;
2498	for (unsigned Arg = 0; Arg < *NumArgumentsInExpansion; ++Arg)
2499	AddSingleCapture(CapturedPattern, Instantiated++);
2500	}
2501	}
2502	return false;
2503	}
2504
2505	Sema::LambdaScopeForCallOperatorInstantiationRAII::
2506	LambdaScopeForCallOperatorInstantiationRAII(
2507	Sema &SemaRef, FunctionDecl *FD, MultiLevelTemplateArgumentList MLTAL,
2508	LocalInstantiationScope &Scope, bool ShouldAddDeclsFromParentScope)
2509	: FunctionScopeRAII(SemaRef) {
2510	if (!isLambdaCallOperator(DC: FD)) {
2511	FunctionScopeRAII::disable();
2512	return;
2513	}
2514
2515	SemaRef.RebuildLambdaScopeInfo(CallOperator: cast<CXXMethodDecl>(Val: FD));
2516
2517	FunctionDecl *FDPattern = getPatternFunctionDecl(FD);
2518	if (!FDPattern)
2519	return;
2520
2521	if (!ShouldAddDeclsFromParentScope)
2522	return;
2523
2524	llvm::SmallVector<std::pair<FunctionDecl *, FunctionDecl *>, 4>
2525	InstantiationAndPatterns;
2526	while (FDPattern && FD) {
2527	InstantiationAndPatterns.emplace_back(Args&: FDPattern, Args&: FD);
2528
2529	FDPattern =
2530	dyn_cast<FunctionDecl>(Val: getLambdaAwareParentOfDeclContext(DC: FDPattern));
2531	FD = dyn_cast<FunctionDecl>(Val: getLambdaAwareParentOfDeclContext(DC: FD));
2532	}
2533
2534	// Add instantiated parameters and local vars to scopes, starting from the
2535	// outermost lambda to the innermost lambda. This ordering ensures that
2536	// the outer instantiations can be found when referenced from within inner
2537	// lambdas.
2538	//
2539	// auto L = [](auto... x) {
2540	// return [](decltype(x)... y) { }; // Instantiating y needs x
2541	// };
2542	//
2543
2544	for (auto [FDPattern, FD] : llvm::reverse(C&: InstantiationAndPatterns)) {
2545	SemaRef.addInstantiatedParametersToScope(Function: FD, PatternDecl: FDPattern, Scope, TemplateArgs: MLTAL);
2546	SemaRef.addInstantiatedLocalVarsToScope(Function: FD, PatternDecl: FDPattern, Scope);
2547
2548	if (isLambdaCallOperator(DC: FD))
2549	SemaRef.addInstantiatedCapturesToScope(Function: FD, PatternDecl: FDPattern, Scope, TemplateArgs: MLTAL);
2550	}
2551	}
2552