1	//===--- ParseTemplate.cpp - Template Parsing -----------------------------===//
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 parsing of C++ templates.
10	//
11	//===----------------------------------------------------------------------===//
12
13	#include "clang/AST/ASTContext.h"
14	#include "clang/AST/DeclTemplate.h"
15	#include "clang/AST/ExprCXX.h"
16	#include "clang/Parse/ParseDiagnostic.h"
17	#include "clang/Parse/Parser.h"
18	#include "clang/Parse/RAIIObjectsForParser.h"
19	#include "clang/Sema/DeclSpec.h"
20	#include "clang/Sema/EnterExpressionEvaluationContext.h"
21	#include "clang/Sema/ParsedTemplate.h"
22	#include "clang/Sema/Scope.h"
23	#include "clang/Sema/SemaDiagnostic.h"
24	#include "llvm/Support/TimeProfiler.h"
25	using namespace clang;
26
27	/// Re-enter a possible template scope, creating as many template parameter
28	/// scopes as necessary.
29	/// \return The number of template parameter scopes entered.
30	unsigned Parser::ReenterTemplateScopes(MultiParseScope &S, Decl *D) {
31	return Actions.ActOnReenterTemplateScope(Template: D, EnterScope: [&] {
32	S.Enter(ScopeFlags: Scope::TemplateParamScope);
33	return Actions.getCurScope();
34	});
35	}
36
37	/// Parse a template declaration, explicit instantiation, or
38	/// explicit specialization.
39	Parser::DeclGroupPtrTy
40	Parser::ParseDeclarationStartingWithTemplate(DeclaratorContext Context,
41	SourceLocation &DeclEnd,
42	ParsedAttributes &AccessAttrs) {
43	ObjCDeclContextSwitch ObjCDC(*this);
44
45	if (Tok.is(K: tok::kw_template) && NextToken().isNot(K: tok::less)) {
46	return ParseExplicitInstantiation(Context, ExternLoc: SourceLocation(), TemplateLoc: ConsumeToken(),
47	DeclEnd, AccessAttrs,
48	AS: AccessSpecifier::AS_none);
49	}
50	return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AccessAttrs,
51	AS: AccessSpecifier::AS_none);
52	}
53
54	/// Parse a template declaration or an explicit specialization.
55	///
56	/// Template declarations include one or more template parameter lists
57	/// and either the function or class template declaration. Explicit
58	/// specializations contain one or more 'template < >' prefixes
59	/// followed by a (possibly templated) declaration. Since the
60	/// syntactic form of both features is nearly identical, we parse all
61	/// of the template headers together and let semantic analysis sort
62	/// the declarations from the explicit specializations.
63	///
64	/// template-declaration: [C++ temp]
65	/// 'export'[opt] 'template' '<' template-parameter-list '>' declaration
66	///
67	/// template-declaration: [C++2a]
68	/// template-head declaration
69	/// template-head concept-definition
70	///
71	/// TODO: requires-clause
72	/// template-head: [C++2a]
73	/// 'template' '<' template-parameter-list '>'
74	/// requires-clause[opt]
75	///
76	/// explicit-specialization: [ C++ temp.expl.spec]
77	/// 'template' '<' '>' declaration
78	Parser::DeclGroupPtrTy Parser::ParseTemplateDeclarationOrSpecialization(
79	DeclaratorContext Context, SourceLocation &DeclEnd,
80	ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
81	assert(Tok.isOneOf(tok::kw_export, tok::kw_template) &&
82	"Token does not start a template declaration.");
83
84	MultiParseScope TemplateParamScopes(*this);
85
86	// Tell the action that names should be checked in the context of
87	// the declaration to come.
88	ParsingDeclRAIIObject
89	ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
90
91	// Parse multiple levels of template headers within this template
92	// parameter scope, e.g.,
93	//
94	// template<typename T>
95	// template<typename U>
96	// class A<T>::B { ... };
97	//
98	// We parse multiple levels non-recursively so that we can build a
99	// single data structure containing all of the template parameter
100	// lists to easily differentiate between the case above and:
101	//
102	// template<typename T>
103	// class A {
104	// template<typename U> class B;
105	// };
106	//
107	// In the first case, the action for declaring A<T>::B receives
108	// both template parameter lists. In the second case, the action for
109	// defining A<T>::B receives just the inner template parameter list
110	// (and retrieves the outer template parameter list from its
111	// context).
112	bool isSpecialization = true;
113	bool LastParamListWasEmpty = false;
114	TemplateParameterLists ParamLists;
115	TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
116
117	do {
118	// Consume the 'export', if any.
119	SourceLocation ExportLoc;
120	TryConsumeToken(Expected: tok::kw_export, Loc&: ExportLoc);
121
122	// Consume the 'template', which should be here.
123	SourceLocation TemplateLoc;
124	if (!TryConsumeToken(Expected: tok::kw_template, Loc&: TemplateLoc)) {
125	Diag(Tok.getLocation(), diag::err_expected_template);
126	return nullptr;
127	}
128
129	// Parse the '<' template-parameter-list '>'
130	SourceLocation LAngleLoc, RAngleLoc;
131	SmallVector<NamedDecl*, 4> TemplateParams;
132	if (ParseTemplateParameters(TemplateScopes&: TemplateParamScopes,
133	Depth: CurTemplateDepthTracker.getDepth(),
134	TemplateParams, LAngleLoc, RAngleLoc)) {
135	// Skip until the semi-colon or a '}'.
136	SkipUntil(T: tok::r_brace, Flags: StopAtSemi | StopBeforeMatch);
137	TryConsumeToken(Expected: tok::semi);
138	return nullptr;
139	}
140
141	ExprResult OptionalRequiresClauseConstraintER;
142	if (!TemplateParams.empty()) {
143	isSpecialization = false;
144	++CurTemplateDepthTracker;
145
146	if (TryConsumeToken(Expected: tok::kw_requires)) {
147	OptionalRequiresClauseConstraintER =
148	Actions.ActOnRequiresClause(ConstraintExpr: ParseConstraintLogicalOrExpression(
149	/*IsTrailingRequiresClause=*/false));
150	if (!OptionalRequiresClauseConstraintER.isUsable()) {
151	// Skip until the semi-colon or a '}'.
152	SkipUntil(T: tok::r_brace, Flags: StopAtSemi | StopBeforeMatch);
153	TryConsumeToken(Expected: tok::semi);
154	return nullptr;
155	}
156	}
157	} else {
158	LastParamListWasEmpty = true;
159	}
160
161	ParamLists.push_back(Elt: Actions.ActOnTemplateParameterList(
162	Depth: CurTemplateDepthTracker.getDepth(), ExportLoc, TemplateLoc, LAngleLoc,
163	Params: TemplateParams, RAngleLoc, RequiresClause: OptionalRequiresClauseConstraintER.get()));
164	} while (Tok.isOneOf(K1: tok::kw_export, K2: tok::kw_template));
165
166	ParsedTemplateInfo TemplateInfo(&ParamLists, isSpecialization,
167	LastParamListWasEmpty);
168
169	// Parse the actual template declaration.
170	if (Tok.is(K: tok::kw_concept))
171	return Actions.ConvertDeclToDeclGroup(
172	Ptr: ParseConceptDefinition(TemplateInfo, DeclEnd));
173
174	return ParseDeclarationAfterTemplate(
175	Context, TemplateInfo, DiagsFromParams&: ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
176	}
177
178	/// Parse a single declaration that declares a template,
179	/// template specialization, or explicit instantiation of a template.
180	///
181	/// \param DeclEnd will receive the source location of the last token
182	/// within this declaration.
183	///
184	/// \param AS the access specifier associated with this
185	/// declaration. Will be AS_none for namespace-scope declarations.
186	///
187	/// \returns the new declaration.
188	Parser::DeclGroupPtrTy Parser::ParseDeclarationAfterTemplate(
189	DeclaratorContext Context, ParsedTemplateInfo &TemplateInfo,
190	ParsingDeclRAIIObject &DiagsFromTParams, SourceLocation &DeclEnd,
191	ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
192	assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
193	"Template information required");
194
195	if (Tok.is(K: tok::kw_static_assert)) {
196	// A static_assert declaration may not be templated.
197	Diag(Tok.getLocation(), diag::err_templated_invalid_declaration)
198	<< TemplateInfo.getSourceRange();
199	// Parse the static_assert declaration to improve error recovery.
200	return Actions.ConvertDeclToDeclGroup(
201	Ptr: ParseStaticAssertDeclaration(DeclEnd));
202	}
203
204	// We are parsing a member template.
205	if (Context == DeclaratorContext::Member)
206	return ParseCXXClassMemberDeclaration(AS, Attr&: AccessAttrs, TemplateInfo,
207	DiagsFromTParams: &DiagsFromTParams);
208
209	ParsedAttributes DeclAttrs(AttrFactory);
210	ParsedAttributes DeclSpecAttrs(AttrFactory);
211
212	// GNU attributes are applied to the declaration specification while the
213	// standard attributes are applied to the declaration. We parse the two
214	// attribute sets into different containters so we can apply them during
215	// the regular parsing process.
216	while (MaybeParseCXX11Attributes(Attrs&: DeclAttrs) ||
217	MaybeParseGNUAttributes(Attrs&: DeclSpecAttrs))
218	;
219
220	if (Tok.is(K: tok::kw_using))
221	return ParseUsingDirectiveOrDeclaration(Context, TemplateInfo, DeclEnd,
222	Attrs&: DeclAttrs);
223
224	// Parse the declaration specifiers, stealing any diagnostics from
225	// the template parameters.
226	ParsingDeclSpec DS(*this, &DiagsFromTParams);
227	DS.SetRangeStart(DeclSpecAttrs.Range.getBegin());
228	DS.SetRangeEnd(DeclSpecAttrs.Range.getEnd());
229	DS.takeAttributesFrom(attrs&: DeclSpecAttrs);
230
231	ParseDeclarationSpecifiers(DS, TemplateInfo, AS,
232	DSC: getDeclSpecContextFromDeclaratorContext(Context));
233
234	if (Tok.is(K: tok::semi)) {
235	ProhibitAttributes(Attrs&: DeclAttrs);
236	DeclEnd = ConsumeToken();
237	RecordDecl *AnonRecord = nullptr;
238	Decl *Decl = Actions.ParsedFreeStandingDeclSpec(
239	S: getCurScope(), AS, DS, DeclAttrs: ParsedAttributesView::none(),
240	TemplateParams: TemplateInfo.TemplateParams ? *TemplateInfo.TemplateParams
241	: MultiTemplateParamsArg(),
242	IsExplicitInstantiation: TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation,
243	AnonRecord);
244	Actions.ActOnDefinedDeclarationSpecifier(D: Decl);
245	assert(!AnonRecord &&
246	"Anonymous unions/structs should not be valid with template");
247	DS.complete(D: Decl);
248	return Actions.ConvertDeclToDeclGroup(Ptr: Decl);
249	}
250
251	if (DS.hasTagDefinition())
252	Actions.ActOnDefinedDeclarationSpecifier(D: DS.getRepAsDecl());
253
254	// Move the attributes from the prefix into the DS.
255	if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation)
256	ProhibitAttributes(Attrs&: DeclAttrs);
257
258	return ParseDeclGroup(DS, Context, Attrs&: DeclAttrs, TemplateInfo, DeclEnd: &DeclEnd);
259	}
260
261	/// \brief Parse a single declaration that declares a concept.
262	///
263	/// \param DeclEnd will receive the source location of the last token
264	/// within this declaration.
265	///
266	/// \returns the new declaration.
267	Decl *
268	Parser::ParseConceptDefinition(const ParsedTemplateInfo &TemplateInfo,
269	SourceLocation &DeclEnd) {
270	assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
271	"Template information required");
272	assert(Tok.is(tok::kw_concept) &&
273	"ParseConceptDefinition must be called when at a 'concept' keyword");
274
275	ConsumeToken(); // Consume 'concept'
276
277	SourceLocation BoolKWLoc;
278	if (TryConsumeToken(tok::kw_bool, BoolKWLoc))
279	Diag(Tok.getLocation(), diag::err_concept_legacy_bool_keyword) <<
280	FixItHint::CreateRemoval(SourceLocation(BoolKWLoc));
281
282	DiagnoseAndSkipCXX11Attributes();
283
284	CXXScopeSpec SS;
285	if (ParseOptionalCXXScopeSpecifier(
286	SS, /*ObjectType=*/nullptr,
287	/*ObjectHasErrors=*/false, /*EnteringContext=*/false,
288	/*MayBePseudoDestructor=*/nullptr,
289	/*IsTypename=*/false, /*LastII=*/nullptr, /*OnlyNamespace=*/true) ||
290	SS.isInvalid()) {
291	SkipUntil(T: tok::semi);
292	return nullptr;
293	}
294
295	if (SS.isNotEmpty())
296	Diag(SS.getBeginLoc(),
297	diag::err_concept_definition_not_identifier);
298
299	UnqualifiedId Result;
300	if (ParseUnqualifiedId(SS, /*ObjectType=*/nullptr,
301	/*ObjectHadErrors=*/false, /*EnteringContext=*/false,
302	/*AllowDestructorName=*/false,
303	/*AllowConstructorName=*/false,
304	/*AllowDeductionGuide=*/false,
305	/*TemplateKWLoc=*/nullptr, Result)) {
306	SkipUntil(T: tok::semi);
307	return nullptr;
308	}
309
310	if (Result.getKind() != UnqualifiedIdKind::IK_Identifier) {
311	Diag(Result.getBeginLoc(), diag::err_concept_definition_not_identifier);
312	SkipUntil(T: tok::semi);
313	return nullptr;
314	}
315
316	const IdentifierInfo *Id = Result.Identifier;
317	SourceLocation IdLoc = Result.getBeginLoc();
318
319	DiagnoseAndSkipCXX11Attributes();
320
321	if (!TryConsumeToken(Expected: tok::equal)) {
322	Diag(Tok.getLocation(), diag::err_expected) << tok::equal;
323	SkipUntil(T: tok::semi);
324	return nullptr;
325	}
326
327	ExprResult ConstraintExprResult =
328	Actions.CorrectDelayedTyposInExpr(ER: ParseConstraintExpression());
329	if (ConstraintExprResult.isInvalid()) {
330	SkipUntil(T: tok::semi);
331	return nullptr;
332	}
333
334	DeclEnd = Tok.getLocation();
335	ExpectAndConsumeSemi(diag::err_expected_semi_declaration);
336	Expr *ConstraintExpr = ConstraintExprResult.get();
337	return Actions.ActOnConceptDefinition(S: getCurScope(),
338	TemplateParameterLists: *TemplateInfo.TemplateParams,
339	Name: Id, NameLoc: IdLoc, ConstraintExpr);
340	}
341
342	/// ParseTemplateParameters - Parses a template-parameter-list enclosed in
343	/// angle brackets. Depth is the depth of this template-parameter-list, which
344	/// is the number of template headers directly enclosing this template header.
345	/// TemplateParams is the current list of template parameters we're building.
346	/// The template parameter we parse will be added to this list. LAngleLoc and
347	/// RAngleLoc will receive the positions of the '<' and '>', respectively,
348	/// that enclose this template parameter list.
349	///
350	/// \returns true if an error occurred, false otherwise.
351	bool Parser::ParseTemplateParameters(
352	MultiParseScope &TemplateScopes, unsigned Depth,
353	SmallVectorImpl<NamedDecl *> &TemplateParams, SourceLocation &LAngleLoc,
354	SourceLocation &RAngleLoc) {
355	// Get the template parameter list.
356	if (!TryConsumeToken(Expected: tok::less, Loc&: LAngleLoc)) {
357	Diag(Tok.getLocation(), diag::err_expected_less_after) << "template";
358	return true;
359	}
360
361	// Try to parse the template parameter list.
362	bool Failed = false;
363	// FIXME: Missing greatergreatergreater support.
364	if (!Tok.is(K: tok::greater) && !Tok.is(K: tok::greatergreater)) {
365	TemplateScopes.Enter(ScopeFlags: Scope::TemplateParamScope);
366	Failed = ParseTemplateParameterList(Depth, TemplateParams);
367	}
368
369	if (Tok.is(K: tok::greatergreater)) {
370	// No diagnostic required here: a template-parameter-list can only be
371	// followed by a declaration or, for a template template parameter, the
372	// 'class' keyword. Therefore, the second '>' will be diagnosed later.
373	// This matters for elegant diagnosis of:
374	// template<template<typename>> struct S;
375	Tok.setKind(tok::greater);
376	RAngleLoc = Tok.getLocation();
377	Tok.setLocation(Tok.getLocation().getLocWithOffset(Offset: 1));
378	} else if (!TryConsumeToken(Expected: tok::greater, Loc&: RAngleLoc) && Failed) {
379	Diag(Tok.getLocation(), diag::err_expected) << tok::greater;
380	return true;
381	}
382	return false;
383	}
384
385	/// ParseTemplateParameterList - Parse a template parameter list. If
386	/// the parsing fails badly (i.e., closing bracket was left out), this
387	/// will try to put the token stream in a reasonable position (closing
388	/// a statement, etc.) and return false.
389	///
390	/// template-parameter-list: [C++ temp]
391	/// template-parameter
392	/// template-parameter-list ',' template-parameter
393	bool
394	Parser::ParseTemplateParameterList(const unsigned Depth,
395	SmallVectorImpl<NamedDecl*> &TemplateParams) {
396	while (true) {
397
398	if (NamedDecl *TmpParam
399	= ParseTemplateParameter(Depth, Position: TemplateParams.size())) {
400	TemplateParams.push_back(Elt: TmpParam);
401	} else {
402	// If we failed to parse a template parameter, skip until we find
403	// a comma or closing brace.
404	SkipUntil(T1: tok::comma, T2: tok::greater, T3: tok::greatergreater,
405	Flags: StopAtSemi | StopBeforeMatch);
406	}
407
408	// Did we find a comma or the end of the template parameter list?
409	if (Tok.is(K: tok::comma)) {
410	ConsumeToken();
411	} else if (Tok.isOneOf(K1: tok::greater, K2: tok::greatergreater)) {
412	// Don't consume this... that's done by template parser.
413	break;
414	} else {
415	// Somebody probably forgot to close the template. Skip ahead and
416	// try to get out of the expression. This error is currently
417	// subsumed by whatever goes on in ParseTemplateParameter.
418	Diag(Tok.getLocation(), diag::err_expected_comma_greater);
419	SkipUntil(T1: tok::comma, T2: tok::greater, T3: tok::greatergreater,
420	Flags: StopAtSemi | StopBeforeMatch);
421	return false;
422	}
423	}
424	return true;
425	}
426
427	/// Determine whether the parser is at the start of a template
428	/// type parameter.
429	Parser::TPResult Parser::isStartOfTemplateTypeParameter() {
430	if (Tok.is(K: tok::kw_class)) {
431	// "class" may be the start of an elaborated-type-specifier or a
432	// type-parameter. Per C++ [temp.param]p3, we prefer the type-parameter.
433	switch (NextToken().getKind()) {
434	case tok::equal:
435	case tok::comma:
436	case tok::greater:
437	case tok::greatergreater:
438	case tok::ellipsis:
439	return TPResult::True;
440
441	case tok::identifier:
442	// This may be either a type-parameter or an elaborated-type-specifier.
443	// We have to look further.
444	break;
445
446	default:
447	return TPResult::False;
448	}
449
450	switch (GetLookAheadToken(N: 2).getKind()) {
451	case tok::equal:
452	case tok::comma:
453	case tok::greater:
454	case tok::greatergreater:
455	return TPResult::True;
456
457	default:
458	return TPResult::False;
459	}
460	}
461
462	if (TryAnnotateTypeConstraint())
463	return TPResult::Error;
464
465	if (isTypeConstraintAnnotation() &&
466	// Next token might be 'auto' or 'decltype', indicating that this
467	// type-constraint is in fact part of a placeholder-type-specifier of a
468	// non-type template parameter.
469	!GetLookAheadToken(N: Tok.is(K: tok::annot_cxxscope) ? 2 : 1)
470	.isOneOf(K1: tok::kw_auto, K2: tok::kw_decltype))
471	return TPResult::True;
472
473	// 'typedef' is a reasonably-common typo/thinko for 'typename', and is
474	// ill-formed otherwise.
475	if (Tok.isNot(K: tok::kw_typename) && Tok.isNot(K: tok::kw_typedef))
476	return TPResult::False;
477
478	// C++ [temp.param]p2:
479	// There is no semantic difference between class and typename in a
480	// template-parameter. typename followed by an unqualified-id
481	// names a template type parameter. typename followed by a
482	// qualified-id denotes the type in a non-type
483	// parameter-declaration.
484	Token Next = NextToken();
485
486	// If we have an identifier, skip over it.
487	if (Next.getKind() == tok::identifier)
488	Next = GetLookAheadToken(N: 2);
489
490	switch (Next.getKind()) {
491	case tok::equal:
492	case tok::comma:
493	case tok::greater:
494	case tok::greatergreater:
495	case tok::ellipsis:
496	return TPResult::True;
497
498	case tok::kw_typename:
499	case tok::kw_typedef:
500	case tok::kw_class:
501	// These indicate that a comma was missed after a type parameter, not that
502	// we have found a non-type parameter.
503	return TPResult::True;
504
505	default:
506	return TPResult::False;
507	}
508	}
509
510	/// ParseTemplateParameter - Parse a template-parameter (C++ [temp.param]).
511	///
512	/// template-parameter: [C++ temp.param]
513	/// type-parameter
514	/// parameter-declaration
515	///
516	/// type-parameter: (See below)
517	/// type-parameter-key ...[opt] identifier[opt]
518	/// type-parameter-key identifier[opt] = type-id
519	/// (C++2a) type-constraint ...[opt] identifier[opt]
520	/// (C++2a) type-constraint identifier[opt] = type-id
521	/// 'template' '<' template-parameter-list '>' type-parameter-key
522	/// ...[opt] identifier[opt]
523	/// 'template' '<' template-parameter-list '>' type-parameter-key
524	/// identifier[opt] '=' id-expression
525	///
526	/// type-parameter-key:
527	/// class
528	/// typename
529	///
530	NamedDecl *Parser::ParseTemplateParameter(unsigned Depth, unsigned Position) {
531
532	switch (isStartOfTemplateTypeParameter()) {
533	case TPResult::True:
534	// Is there just a typo in the input code? ('typedef' instead of
535	// 'typename')
536	if (Tok.is(K: tok::kw_typedef)) {
537	Diag(Tok.getLocation(), diag::err_expected_template_parameter);
538
539	Diag(Tok.getLocation(), diag::note_meant_to_use_typename)
540	<< FixItHint::CreateReplacement(CharSourceRange::getCharRange(
541	Tok.getLocation(),
542	Tok.getEndLoc()),
543	"typename");
544
545	Tok.setKind(tok::kw_typename);
546	}
547
548	return ParseTypeParameter(Depth, Position);
549	case TPResult::False:
550	break;
551
552	case TPResult::Error: {
553	// We return an invalid parameter as opposed to null to avoid having bogus
554	// diagnostics about an empty template parameter list.
555	// FIXME: Fix ParseTemplateParameterList to better handle nullptr results
556	// from here.
557	// Return a NTTP as if there was an error in a scope specifier, the user
558	// probably meant to write the type of a NTTP.
559	DeclSpec DS(getAttrFactory());
560	DS.SetTypeSpecError();
561	Declarator D(DS, ParsedAttributesView::none(),
562	DeclaratorContext::TemplateParam);
563	D.SetIdentifier(Id: nullptr, IdLoc: Tok.getLocation());
564	D.setInvalidType(true);
565	NamedDecl *ErrorParam = Actions.ActOnNonTypeTemplateParameter(
566	S: getCurScope(), D, Depth, Position, /*EqualLoc=*/SourceLocation(),
567	/*DefaultArg=*/nullptr);
568	ErrorParam->setInvalidDecl(true);
569	SkipUntil(T1: tok::comma, T2: tok::greater, T3: tok::greatergreater,
570	Flags: StopAtSemi | StopBeforeMatch);
571	return ErrorParam;
572	}
573
574	case TPResult::Ambiguous:
575	llvm_unreachable("template param classification can't be ambiguous");
576	}
577
578	if (Tok.is(K: tok::kw_template))
579	return ParseTemplateTemplateParameter(Depth, Position);
580
581	// If it's none of the above, then it must be a parameter declaration.
582	// NOTE: This will pick up errors in the closure of the template parameter
583	// list (e.g., template < ; Check here to implement >> style closures.
584	return ParseNonTypeTemplateParameter(Depth, Position);
585	}
586
587	/// Check whether the current token is a template-id annotation denoting a
588	/// type-constraint.
589	bool Parser::isTypeConstraintAnnotation() {
590	const Token &T = Tok.is(K: tok::annot_cxxscope) ? NextToken() : Tok;
591	if (T.isNot(K: tok::annot_template_id))
592	return false;
593	const auto *ExistingAnnot =
594	static_cast<TemplateIdAnnotation *>(T.getAnnotationValue());
595	return ExistingAnnot->Kind == TNK_Concept_template;
596	}
597
598	/// Try parsing a type-constraint at the current location.
599	///
600	/// type-constraint:
601	/// nested-name-specifier[opt] concept-name
602	/// nested-name-specifier[opt] concept-name
603	/// '<' template-argument-list[opt] '>'[opt]
604	///
605	/// \returns true if an error occurred, and false otherwise.
606	bool Parser::TryAnnotateTypeConstraint() {
607	if (!getLangOpts().CPlusPlus20)
608	return false;
609	CXXScopeSpec SS;
610	bool WasScopeAnnotation = Tok.is(K: tok::annot_cxxscope);
611	if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
612	/*ObjectHasErrors=*/false,
613	/*EnteringContext=*/false,
614	/*MayBePseudoDestructor=*/nullptr,
615	// If this is not a type-constraint, then
616	// this scope-spec is part of the typename
617	// of a non-type template parameter
618	/*IsTypename=*/true, /*LastII=*/nullptr,
619	// We won't find concepts in
620	// non-namespaces anyway, so might as well
621	// parse this correctly for possible type
622	// names.
623	/*OnlyNamespace=*/false))
624	return true;
625
626	if (Tok.is(K: tok::identifier)) {
627	UnqualifiedId PossibleConceptName;
628	PossibleConceptName.setIdentifier(Id: Tok.getIdentifierInfo(),
629	IdLoc: Tok.getLocation());
630
631	TemplateTy PossibleConcept;
632	bool MemberOfUnknownSpecialization = false;
633	auto TNK = Actions.isTemplateName(S: getCurScope(), SS,
634	/*hasTemplateKeyword=*/false,
635	Name: PossibleConceptName,
636	/*ObjectType=*/ParsedType(),
637	/*EnteringContext=*/false,
638	Template&: PossibleConcept,
639	MemberOfUnknownSpecialization,
640	/*Disambiguation=*/true);
641	if (MemberOfUnknownSpecialization || !PossibleConcept ||
642	TNK != TNK_Concept_template) {
643	if (SS.isNotEmpty())
644	AnnotateScopeToken(SS, IsNewAnnotation: !WasScopeAnnotation);
645	return false;
646	}
647
648	// At this point we're sure we're dealing with a constrained parameter. It
649	// may or may not have a template parameter list following the concept
650	// name.
651	if (AnnotateTemplateIdToken(Template: PossibleConcept, TNK, SS,
652	/*TemplateKWLoc=*/SourceLocation(),
653	TemplateName&: PossibleConceptName,
654	/*AllowTypeAnnotation=*/false,
655	/*TypeConstraint=*/true))
656	return true;
657	}
658
659	if (SS.isNotEmpty())
660	AnnotateScopeToken(SS, IsNewAnnotation: !WasScopeAnnotation);
661	return false;
662	}
663
664	/// ParseTypeParameter - Parse a template type parameter (C++ [temp.param]).
665	/// Other kinds of template parameters are parsed in
666	/// ParseTemplateTemplateParameter and ParseNonTypeTemplateParameter.
667	///
668	/// type-parameter: [C++ temp.param]
669	/// 'class' ...[opt][C++0x] identifier[opt]
670	/// 'class' identifier[opt] '=' type-id
671	/// 'typename' ...[opt][C++0x] identifier[opt]
672	/// 'typename' identifier[opt] '=' type-id
673	NamedDecl *Parser::ParseTypeParameter(unsigned Depth, unsigned Position) {
674	assert((Tok.isOneOf(tok::kw_class, tok::kw_typename) ||
675	isTypeConstraintAnnotation()) &&
676	"A type-parameter starts with 'class', 'typename' or a "
677	"type-constraint");
678
679	CXXScopeSpec TypeConstraintSS;
680	TemplateIdAnnotation *TypeConstraint = nullptr;
681	bool TypenameKeyword = false;
682	SourceLocation KeyLoc;
683	ParseOptionalCXXScopeSpecifier(SS&: TypeConstraintSS, /*ObjectType=*/nullptr,
684	/*ObjectHasErrors=*/false,
685	/*EnteringContext*/ false);
686	if (Tok.is(K: tok::annot_template_id)) {
687	// Consume the 'type-constraint'.
688	TypeConstraint =
689	static_cast<TemplateIdAnnotation *>(Tok.getAnnotationValue());
690	assert(TypeConstraint->Kind == TNK_Concept_template &&
691	"stray non-concept template-id annotation");
692	KeyLoc = ConsumeAnnotationToken();
693	} else {
694	assert(TypeConstraintSS.isEmpty() &&
695	"expected type constraint after scope specifier");
696
697	// Consume the 'class' or 'typename' keyword.
698	TypenameKeyword = Tok.is(K: tok::kw_typename);
699	KeyLoc = ConsumeToken();
700	}
701
702	// Grab the ellipsis (if given).
703	SourceLocation EllipsisLoc;
704	if (TryConsumeToken(Expected: tok::ellipsis, Loc&: EllipsisLoc)) {
705	Diag(EllipsisLoc,
706	getLangOpts().CPlusPlus11
707	? diag::warn_cxx98_compat_variadic_templates
708	: diag::ext_variadic_templates);
709	}
710
711	// Grab the template parameter name (if given)
712	SourceLocation NameLoc = Tok.getLocation();
713	IdentifierInfo *ParamName = nullptr;
714	if (Tok.is(K: tok::identifier)) {
715	ParamName = Tok.getIdentifierInfo();
716	ConsumeToken();
717	} else if (Tok.isOneOf(K1: tok::equal, Ks: tok::comma, Ks: tok::greater,
718	Ks: tok::greatergreater)) {
719	// Unnamed template parameter. Don't have to do anything here, just
720	// don't consume this token.
721	} else {
722	Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
723	return nullptr;
724	}
725
726	// Recover from misplaced ellipsis.
727	bool AlreadyHasEllipsis = EllipsisLoc.isValid();
728	if (TryConsumeToken(Expected: tok::ellipsis, Loc&: EllipsisLoc))
729	DiagnoseMisplacedEllipsis(EllipsisLoc, CorrectLoc: NameLoc, AlreadyHasEllipsis, IdentifierHasName: true);
730
731	// Grab a default argument (if available).
732	// Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
733	// we introduce the type parameter into the local scope.
734	SourceLocation EqualLoc;
735	ParsedType DefaultArg;
736	std::optional<DelayTemplateIdDestructionRAII> DontDestructTemplateIds;
737	if (TryConsumeToken(Expected: tok::equal, Loc&: EqualLoc)) {
738	// The default argument might contain a lambda declaration; avoid destroying
739	// parsed template ids at the end of that declaration because they can be
740	// used in a type constraint later.
741	DontDestructTemplateIds.emplace(args&: *this, /*DelayTemplateIdDestruction=*/args: true);
742	// The default argument may declare template parameters, notably
743	// if it contains a generic lambda, so we need to increase
744	// the template depth as these parameters would not be instantiated
745	// at the current level.
746	TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
747	++CurTemplateDepthTracker;
748	DefaultArg =
749	ParseTypeName(/*Range=*/nullptr, Context: DeclaratorContext::TemplateTypeArg)
750	.get();
751	}
752
753	NamedDecl *NewDecl = Actions.ActOnTypeParameter(S: getCurScope(),
754	Typename: TypenameKeyword, EllipsisLoc,
755	KeyLoc, ParamName, ParamNameLoc: NameLoc,
756	Depth, Position, EqualLoc,
757	DefaultArg,
758	HasTypeConstraint: TypeConstraint != nullptr);
759
760	if (TypeConstraint) {
761	Actions.ActOnTypeConstraint(SS: TypeConstraintSS, TypeConstraint,
762	ConstrainedParameter: cast<TemplateTypeParmDecl>(Val: NewDecl),
763	EllipsisLoc);
764	}
765
766	return NewDecl;
767	}
768
769	/// ParseTemplateTemplateParameter - Handle the parsing of template
770	/// template parameters.
771	///
772	/// type-parameter: [C++ temp.param]
773	/// template-head type-parameter-key ...[opt] identifier[opt]
774	/// template-head type-parameter-key identifier[opt] = id-expression
775	/// type-parameter-key:
776	/// 'class'
777	/// 'typename' [C++1z]
778	/// template-head: [C++2a]
779	/// 'template' '<' template-parameter-list '>'
780	/// requires-clause[opt]
781	NamedDecl *Parser::ParseTemplateTemplateParameter(unsigned Depth,
782	unsigned Position) {
783	assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");
784
785	// Handle the template <...> part.
786	SourceLocation TemplateLoc = ConsumeToken();
787	SmallVector<NamedDecl*,8> TemplateParams;
788	SourceLocation LAngleLoc, RAngleLoc;
789	ExprResult OptionalRequiresClauseConstraintER;
790	{
791	MultiParseScope TemplateParmScope(*this);
792	if (ParseTemplateParameters(TemplateScopes&: TemplateParmScope, Depth: Depth + 1, TemplateParams,
793	LAngleLoc, RAngleLoc)) {
794	return nullptr;
795	}
796	if (TryConsumeToken(Expected: tok::kw_requires)) {
797	OptionalRequiresClauseConstraintER =
798	Actions.ActOnRequiresClause(ConstraintExpr: ParseConstraintLogicalOrExpression(
799	/*IsTrailingRequiresClause=*/false));
800	if (!OptionalRequiresClauseConstraintER.isUsable()) {
801	SkipUntil(T1: tok::comma, T2: tok::greater, T3: tok::greatergreater,
802	Flags: StopAtSemi | StopBeforeMatch);
803	return nullptr;
804	}
805	}
806	}
807
808	// Provide an ExtWarn if the C++1z feature of using 'typename' here is used.
809	// Generate a meaningful error if the user forgot to put class before the
810	// identifier, comma, or greater. Provide a fixit if the identifier, comma,
811	// or greater appear immediately or after 'struct'. In the latter case,
812	// replace the keyword with 'class'.
813	bool TypenameKeyword = false;
814	if (!TryConsumeToken(Expected: tok::kw_class)) {
815	bool Replace = Tok.isOneOf(K1: tok::kw_typename, K2: tok::kw_struct);
816	const Token &Next = Tok.is(K: tok::kw_struct) ? NextToken() : Tok;
817	if (Tok.is(K: tok::kw_typename)) {
818	TypenameKeyword = true;
819	Diag(Tok.getLocation(),
820	getLangOpts().CPlusPlus17
821	? diag::warn_cxx14_compat_template_template_param_typename
822	: diag::ext_template_template_param_typename)
823	<< (!getLangOpts().CPlusPlus17
824	? FixItHint::CreateReplacement(Tok.getLocation(), "class")
825	: FixItHint());
826	} else if (Next.isOneOf(K1: tok::identifier, Ks: tok::comma, Ks: tok::greater,
827	Ks: tok::greatergreater, Ks: tok::ellipsis)) {
828	Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
829	<< getLangOpts().CPlusPlus17
830	<< (Replace
831	? FixItHint::CreateReplacement(Tok.getLocation(), "class")
832	: FixItHint::CreateInsertion(Tok.getLocation(), "class "));
833	} else
834	Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
835	<< getLangOpts().CPlusPlus17;
836
837	if (Replace)
838	ConsumeToken();
839	}
840
841	// Parse the ellipsis, if given.
842	SourceLocation EllipsisLoc;
843	if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
844	Diag(EllipsisLoc,
845	getLangOpts().CPlusPlus11
846	? diag::warn_cxx98_compat_variadic_templates
847	: diag::ext_variadic_templates);
848
849	// Get the identifier, if given.
850	SourceLocation NameLoc = Tok.getLocation();
851	IdentifierInfo *ParamName = nullptr;
852	if (Tok.is(K: tok::identifier)) {
853	ParamName = Tok.getIdentifierInfo();
854	ConsumeToken();
855	} else if (Tok.isOneOf(K1: tok::equal, Ks: tok::comma, Ks: tok::greater,
856	Ks: tok::greatergreater)) {
857	// Unnamed template parameter. Don't have to do anything here, just
858	// don't consume this token.
859	} else {
860	Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
861	return nullptr;
862	}
863
864	// Recover from misplaced ellipsis.
865	bool AlreadyHasEllipsis = EllipsisLoc.isValid();
866	if (TryConsumeToken(Expected: tok::ellipsis, Loc&: EllipsisLoc))
867	DiagnoseMisplacedEllipsis(EllipsisLoc, CorrectLoc: NameLoc, AlreadyHasEllipsis, IdentifierHasName: true);
868
869	TemplateParameterList *ParamList = Actions.ActOnTemplateParameterList(
870	Depth, ExportLoc: SourceLocation(), TemplateLoc, LAngleLoc, Params: TemplateParams,
871	RAngleLoc, RequiresClause: OptionalRequiresClauseConstraintER.get());
872
873	// Grab a default argument (if available).
874	// Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
875	// we introduce the template parameter into the local scope.
876	SourceLocation EqualLoc;
877	ParsedTemplateArgument DefaultArg;
878	if (TryConsumeToken(Expected: tok::equal, Loc&: EqualLoc)) {
879	DefaultArg = ParseTemplateTemplateArgument();
880	if (DefaultArg.isInvalid()) {
881	Diag(Tok.getLocation(),
882	diag::err_default_template_template_parameter_not_template);
883	SkipUntil(T1: tok::comma, T2: tok::greater, T3: tok::greatergreater,
884	Flags: StopAtSemi | StopBeforeMatch);
885	}
886	}
887
888	return Actions.ActOnTemplateTemplateParameter(
889	S: getCurScope(), TmpLoc: TemplateLoc, Params: ParamList, Typename: TypenameKeyword, EllipsisLoc,
890	ParamName, ParamNameLoc: NameLoc, Depth, Position, EqualLoc, DefaultArg);
891	}
892
893	/// ParseNonTypeTemplateParameter - Handle the parsing of non-type
894	/// template parameters (e.g., in "template<int Size> class array;").
895	///
896	/// template-parameter:
897	/// ...
898	/// parameter-declaration
899	NamedDecl *
900	Parser::ParseNonTypeTemplateParameter(unsigned Depth, unsigned Position) {
901	// Parse the declaration-specifiers (i.e., the type).
902	// FIXME: The type should probably be restricted in some way... Not all
903	// declarators (parts of declarators?) are accepted for parameters.
904	DeclSpec DS(AttrFactory);
905	ParseDeclarationSpecifiers(DS, TemplateInfo: ParsedTemplateInfo(), AS: AS_none,
906	DSC: DeclSpecContext::DSC_template_param);
907
908	// Parse this as a typename.
909	Declarator ParamDecl(DS, ParsedAttributesView::none(),
910	DeclaratorContext::TemplateParam);
911	ParseDeclarator(D&: ParamDecl);
912	if (DS.getTypeSpecType() == DeclSpec::TST_unspecified) {
913	Diag(Tok.getLocation(), diag::err_expected_template_parameter);
914	return nullptr;
915	}
916
917	// Recover from misplaced ellipsis.
918	SourceLocation EllipsisLoc;
919	if (TryConsumeToken(Expected: tok::ellipsis, Loc&: EllipsisLoc))
920	DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, D&: ParamDecl);
921
922	// If there is a default value, parse it.
923	// Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
924	// we introduce the template parameter into the local scope.
925	SourceLocation EqualLoc;
926	ExprResult DefaultArg;
927	if (TryConsumeToken(Expected: tok::equal, Loc&: EqualLoc)) {
928	if (Tok.is(K: tok::l_paren) && NextToken().is(K: tok::l_brace)) {
929	Diag(Tok.getLocation(), diag::err_stmt_expr_in_default_arg) << 1;
930	SkipUntil(T1: tok::comma, T2: tok::greater, Flags: StopAtSemi | StopBeforeMatch);
931	} else {
932	// C++ [temp.param]p15:
933	// When parsing a default template-argument for a non-type
934	// template-parameter, the first non-nested > is taken as the
935	// end of the template-parameter-list rather than a greater-than
936	// operator.
937	GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
938
939	// The default argument may declare template parameters, notably
940	// if it contains a generic lambda, so we need to increase
941	// the template depth as these parameters would not be instantiated
942	// at the current level.
943	TemplateParameterDepthRAII CurTemplateDepthTracker(
944	TemplateParameterDepth);
945	++CurTemplateDepthTracker;
946	EnterExpressionEvaluationContext ConstantEvaluated(
947	Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
948	DefaultArg = Actions.CorrectDelayedTyposInExpr(ER: ParseInitializer());
949	if (DefaultArg.isInvalid())
950	SkipUntil(T1: tok::comma, T2: tok::greater, Flags: StopAtSemi | StopBeforeMatch);
951	}
952	}
953
954	// Create the parameter.
955	return Actions.ActOnNonTypeTemplateParameter(S: getCurScope(), D&: ParamDecl,
956	Depth, Position, EqualLoc,
957	DefaultArg: DefaultArg.get());
958	}
959
960	void Parser::DiagnoseMisplacedEllipsis(SourceLocation EllipsisLoc,
961	SourceLocation CorrectLoc,
962	bool AlreadyHasEllipsis,
963	bool IdentifierHasName) {
964	FixItHint Insertion;
965	if (!AlreadyHasEllipsis)
966	Insertion = FixItHint::CreateInsertion(InsertionLoc: CorrectLoc, Code: "...");
967	Diag(EllipsisLoc, diag::err_misplaced_ellipsis_in_declaration)
968	<< FixItHint::CreateRemoval(EllipsisLoc) << Insertion
969	<< !IdentifierHasName;
970	}
971
972	void Parser::DiagnoseMisplacedEllipsisInDeclarator(SourceLocation EllipsisLoc,
973	Declarator &D) {
974	assert(EllipsisLoc.isValid());
975	bool AlreadyHasEllipsis = D.getEllipsisLoc().isValid();
976	if (!AlreadyHasEllipsis)
977	D.setEllipsisLoc(EllipsisLoc);
978	DiagnoseMisplacedEllipsis(EllipsisLoc, CorrectLoc: D.getIdentifierLoc(),
979	AlreadyHasEllipsis, IdentifierHasName: D.hasName());
980	}
981
982	/// Parses a '>' at the end of a template list.
983	///
984	/// If this function encounters '>>', '>>>', '>=', or '>>=', it tries
985	/// to determine if these tokens were supposed to be a '>' followed by
986	/// '>', '>>', '>=', or '>='. It emits an appropriate diagnostic if necessary.
987	///
988	/// \param RAngleLoc the location of the consumed '>'.
989	///
990	/// \param ConsumeLastToken if true, the '>' is consumed.
991	///
992	/// \param ObjCGenericList if true, this is the '>' closing an Objective-C
993	/// type parameter or type argument list, rather than a C++ template parameter
994	/// or argument list.
995	///
996	/// \returns true, if current token does not start with '>', false otherwise.
997	bool Parser::ParseGreaterThanInTemplateList(SourceLocation LAngleLoc,
998	SourceLocation &RAngleLoc,
999	bool ConsumeLastToken,
1000	bool ObjCGenericList) {
1001	// What will be left once we've consumed the '>'.
1002	tok::TokenKind RemainingToken;
1003	const char *ReplacementStr = "> >";
1004	bool MergeWithNextToken = false;
1005
1006	switch (Tok.getKind()) {
1007	default:
1008	Diag(getEndOfPreviousToken(), diag::err_expected) << tok::greater;
1009	Diag(LAngleLoc, diag::note_matching) << tok::less;
1010	return true;
1011
1012	case tok::greater:
1013	// Determine the location of the '>' token. Only consume this token
1014	// if the caller asked us to.
1015	RAngleLoc = Tok.getLocation();
1016	if (ConsumeLastToken)
1017	ConsumeToken();
1018	return false;
1019
1020	case tok::greatergreater:
1021	RemainingToken = tok::greater;
1022	break;
1023
1024	case tok::greatergreatergreater:
1025	RemainingToken = tok::greatergreater;
1026	break;
1027
1028	case tok::greaterequal:
1029	RemainingToken = tok::equal;
1030	ReplacementStr = "> =";
1031
1032	// Join two adjacent '=' tokens into one, for cases like:
1033	// void (*p)() = f<int>;
1034	// return f<int>==p;
1035	if (NextToken().is(K: tok::equal) &&
1036	areTokensAdjacent(A: Tok, B: NextToken())) {
1037	RemainingToken = tok::equalequal;
1038	MergeWithNextToken = true;
1039	}
1040	break;
1041
1042	case tok::greatergreaterequal:
1043	RemainingToken = tok::greaterequal;
1044	break;
1045	}
1046
1047	// This template-id is terminated by a token that starts with a '>'.
1048	// Outside C++11 and Objective-C, this is now error recovery.
1049	//
1050	// C++11 allows this when the token is '>>', and in CUDA + C++11 mode, we
1051	// extend that treatment to also apply to the '>>>' token.
1052	//
1053	// Objective-C allows this in its type parameter / argument lists.
1054
1055	SourceLocation TokBeforeGreaterLoc = PrevTokLocation;
1056	SourceLocation TokLoc = Tok.getLocation();
1057	Token Next = NextToken();
1058
1059	// Whether splitting the current token after the '>' would undesirably result
1060	// in the remaining token pasting with the token after it. This excludes the
1061	// MergeWithNextToken cases, which we've already handled.
1062	bool PreventMergeWithNextToken =
1063	(RemainingToken == tok::greater ||
1064	RemainingToken == tok::greatergreater) &&
1065	(Next.isOneOf(K1: tok::greater, Ks: tok::greatergreater,
1066	Ks: tok::greatergreatergreater, Ks: tok::equal, Ks: tok::greaterequal,
1067	Ks: tok::greatergreaterequal, Ks: tok::equalequal)) &&
1068	areTokensAdjacent(A: Tok, B: Next);
1069
1070	// Diagnose this situation as appropriate.
1071	if (!ObjCGenericList) {
1072	// The source range of the replaced token(s).
1073	CharSourceRange ReplacementRange = CharSourceRange::getCharRange(
1074	B: TokLoc, E: Lexer::AdvanceToTokenCharacter(TokStart: TokLoc, Characters: 2, SM: PP.getSourceManager(),
1075	LangOpts: getLangOpts()));
1076
1077	// A hint to put a space between the '>>'s. In order to make the hint as
1078	// clear as possible, we include the characters either side of the space in
1079	// the replacement, rather than just inserting a space at SecondCharLoc.
1080	FixItHint Hint1 = FixItHint::CreateReplacement(RemoveRange: ReplacementRange,
1081	Code: ReplacementStr);
1082
1083	// A hint to put another space after the token, if it would otherwise be
1084	// lexed differently.
1085	FixItHint Hint2;
1086	if (PreventMergeWithNextToken)
1087	Hint2 = FixItHint::CreateInsertion(InsertionLoc: Next.getLocation(), Code: " ");
1088
1089	unsigned DiagId = diag::err_two_right_angle_brackets_need_space;
1090	if (getLangOpts().CPlusPlus11 &&
1091	(Tok.is(tok::greatergreater) || Tok.is(tok::greatergreatergreater)))
1092	DiagId = diag::warn_cxx98_compat_two_right_angle_brackets;
1093	else if (Tok.is(tok::greaterequal))
1094	DiagId = diag::err_right_angle_bracket_equal_needs_space;
1095	Diag(Loc: TokLoc, DiagID: DiagId) << Hint1 << Hint2;
1096	}
1097
1098	// Find the "length" of the resulting '>' token. This is not always 1, as it
1099	// can contain escaped newlines.
1100	unsigned GreaterLength = Lexer::getTokenPrefixLength(
1101	TokStart: TokLoc, CharNo: 1, SM: PP.getSourceManager(), LangOpts: getLangOpts());
1102
1103	// Annotate the source buffer to indicate that we split the token after the
1104	// '>'. This allows us to properly find the end of, and extract the spelling
1105	// of, the '>' token later.
1106	RAngleLoc = PP.SplitToken(TokLoc, Length: GreaterLength);
1107
1108	// Strip the initial '>' from the token.
1109	bool CachingTokens = PP.IsPreviousCachedToken(Tok);
1110
1111	Token Greater = Tok;
1112	Greater.setLocation(RAngleLoc);
1113	Greater.setKind(tok::greater);
1114	Greater.setLength(GreaterLength);
1115
1116	unsigned OldLength = Tok.getLength();
1117	if (MergeWithNextToken) {
1118	ConsumeToken();
1119	OldLength += Tok.getLength();
1120	}
1121
1122	Tok.setKind(RemainingToken);
1123	Tok.setLength(OldLength - GreaterLength);
1124
1125	// Split the second token if lexing it normally would lex a different token
1126	// (eg, the fifth token in 'A<B>>>' should re-lex as '>', not '>>').
1127	SourceLocation AfterGreaterLoc = TokLoc.getLocWithOffset(Offset: GreaterLength);
1128	if (PreventMergeWithNextToken)
1129	AfterGreaterLoc = PP.SplitToken(TokLoc: AfterGreaterLoc, Length: Tok.getLength());
1130	Tok.setLocation(AfterGreaterLoc);
1131
1132	// Update the token cache to match what we just did if necessary.
1133	if (CachingTokens) {
1134	// If the previous cached token is being merged, delete it.
1135	if (MergeWithNextToken)
1136	PP.ReplacePreviousCachedToken(NewToks: {});
1137
1138	if (ConsumeLastToken)
1139	PP.ReplacePreviousCachedToken(NewToks: {Greater, Tok});
1140	else
1141	PP.ReplacePreviousCachedToken(NewToks: {Greater});
1142	}
1143
1144	if (ConsumeLastToken) {
1145	PrevTokLocation = RAngleLoc;
1146	} else {
1147	PrevTokLocation = TokBeforeGreaterLoc;
1148	PP.EnterToken(Tok, /*IsReinject=*/true);
1149	Tok = Greater;
1150	}
1151
1152	return false;
1153	}
1154
1155	/// Parses a template-id that after the template name has
1156	/// already been parsed.
1157	///
1158	/// This routine takes care of parsing the enclosed template argument
1159	/// list ('<' template-parameter-list [opt] '>') and placing the
1160	/// results into a form that can be transferred to semantic analysis.
1161	///
1162	/// \param ConsumeLastToken if true, then we will consume the last
1163	/// token that forms the template-id. Otherwise, we will leave the
1164	/// last token in the stream (e.g., so that it can be replaced with an
1165	/// annotation token).
1166	bool Parser::ParseTemplateIdAfterTemplateName(bool ConsumeLastToken,
1167	SourceLocation &LAngleLoc,
1168	TemplateArgList &TemplateArgs,
1169	SourceLocation &RAngleLoc,
1170	TemplateTy Template) {
1171	assert(Tok.is(tok::less) && "Must have already parsed the template-name");
1172
1173	// Consume the '<'.
1174	LAngleLoc = ConsumeToken();
1175
1176	// Parse the optional template-argument-list.
1177	bool Invalid = false;
1178	{
1179	GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
1180	if (!Tok.isOneOf(K1: tok::greater, Ks: tok::greatergreater,
1181	Ks: tok::greatergreatergreater, Ks: tok::greaterequal,
1182	Ks: tok::greatergreaterequal))
1183	Invalid = ParseTemplateArgumentList(TemplateArgs, Template, OpenLoc: LAngleLoc);
1184
1185	if (Invalid) {
1186	// Try to find the closing '>'.
1187	if (getLangOpts().CPlusPlus11)
1188	SkipUntil(T1: tok::greater, T2: tok::greatergreater,
1189	T3: tok::greatergreatergreater, Flags: StopAtSemi | StopBeforeMatch);
1190	else
1191	SkipUntil(T: tok::greater, Flags: StopAtSemi | StopBeforeMatch);
1192	}
1193	}
1194
1195	return ParseGreaterThanInTemplateList(LAngleLoc, RAngleLoc, ConsumeLastToken,
1196	/*ObjCGenericList=*/false) ||
1197	Invalid;
1198	}
1199
1200	/// Replace the tokens that form a simple-template-id with an
1201	/// annotation token containing the complete template-id.
1202	///
1203	/// The first token in the stream must be the name of a template that
1204	/// is followed by a '<'. This routine will parse the complete
1205	/// simple-template-id and replace the tokens with a single annotation
1206	/// token with one of two different kinds: if the template-id names a
1207	/// type (and \p AllowTypeAnnotation is true), the annotation token is
1208	/// a type annotation that includes the optional nested-name-specifier
1209	/// (\p SS). Otherwise, the annotation token is a template-id
1210	/// annotation that does not include the optional
1211	/// nested-name-specifier.
1212	///
1213	/// \param Template the declaration of the template named by the first
1214	/// token (an identifier), as returned from \c Action::isTemplateName().
1215	///
1216	/// \param TNK the kind of template that \p Template
1217	/// refers to, as returned from \c Action::isTemplateName().
1218	///
1219	/// \param SS if non-NULL, the nested-name-specifier that precedes
1220	/// this template name.
1221	///
1222	/// \param TemplateKWLoc if valid, specifies that this template-id
1223	/// annotation was preceded by the 'template' keyword and gives the
1224	/// location of that keyword. If invalid (the default), then this
1225	/// template-id was not preceded by a 'template' keyword.
1226	///
1227	/// \param AllowTypeAnnotation if true (the default), then a
1228	/// simple-template-id that refers to a class template, template
1229	/// template parameter, or other template that produces a type will be
1230	/// replaced with a type annotation token. Otherwise, the
1231	/// simple-template-id is always replaced with a template-id
1232	/// annotation token.
1233	///
1234	/// \param TypeConstraint if true, then this is actually a type-constraint,
1235	/// meaning that the template argument list can be omitted (and the template in
1236	/// question must be a concept).
1237	///
1238	/// If an unrecoverable parse error occurs and no annotation token can be
1239	/// formed, this function returns true.
1240	///
1241	bool Parser::AnnotateTemplateIdToken(TemplateTy Template, TemplateNameKind TNK,
1242	CXXScopeSpec &SS,
1243	SourceLocation TemplateKWLoc,
1244	UnqualifiedId &TemplateName,
1245	bool AllowTypeAnnotation,
1246	bool TypeConstraint) {
1247	assert(getLangOpts().CPlusPlus && "Can only annotate template-ids in C++");
1248	assert((Tok.is(tok::less) || TypeConstraint) &&
1249	"Parser isn't at the beginning of a template-id");
1250	assert(!(TypeConstraint && AllowTypeAnnotation) && "type-constraint can't be "
1251	"a type annotation");
1252	assert((!TypeConstraint || TNK == TNK_Concept_template) && "type-constraint "
1253	"must accompany a concept name");
1254	assert((Template || TNK == TNK_Non_template) && "missing template name");
1255
1256	// Consume the template-name.
1257	SourceLocation TemplateNameLoc = TemplateName.getSourceRange().getBegin();
1258
1259	// Parse the enclosed template argument list.
1260	SourceLocation LAngleLoc, RAngleLoc;
1261	TemplateArgList TemplateArgs;
1262	bool ArgsInvalid = false;
1263	if (!TypeConstraint || Tok.is(K: tok::less)) {
1264	ArgsInvalid = ParseTemplateIdAfterTemplateName(
1265	ConsumeLastToken: false, LAngleLoc, TemplateArgs, RAngleLoc, Template);
1266	// If we couldn't recover from invalid arguments, don't form an annotation
1267	// token -- we don't know how much to annotate.
1268	// FIXME: This can lead to duplicate diagnostics if we retry parsing this
1269	// template-id in another context. Try to annotate anyway?
1270	if (RAngleLoc.isInvalid())
1271	return true;
1272	}
1273
1274	ASTTemplateArgsPtr TemplateArgsPtr(TemplateArgs);
1275
1276	// Build the annotation token.
1277	if (TNK == TNK_Type_template && AllowTypeAnnotation) {
1278	TypeResult Type = ArgsInvalid
1279	? TypeError()
1280	: Actions.ActOnTemplateIdType(
1281	S: getCurScope(), SS, TemplateKWLoc, Template,
1282	TemplateII: TemplateName.Identifier, TemplateIILoc: TemplateNameLoc,
1283	LAngleLoc, TemplateArgs: TemplateArgsPtr, RAngleLoc);
1284
1285	Tok.setKind(tok::annot_typename);
1286	setTypeAnnotation(Tok, T: Type);
1287	if (SS.isNotEmpty())
1288	Tok.setLocation(SS.getBeginLoc());
1289	else if (TemplateKWLoc.isValid())
1290	Tok.setLocation(TemplateKWLoc);
1291	else
1292	Tok.setLocation(TemplateNameLoc);
1293	} else {
1294	// Build a template-id annotation token that can be processed
1295	// later.
1296	Tok.setKind(tok::annot_template_id);
1297
1298	const IdentifierInfo *TemplateII =
1299	TemplateName.getKind() == UnqualifiedIdKind::IK_Identifier
1300	? TemplateName.Identifier
1301	: nullptr;
1302
1303	OverloadedOperatorKind OpKind =
1304	TemplateName.getKind() == UnqualifiedIdKind::IK_Identifier
1305	? OO_None
1306	: TemplateName.OperatorFunctionId.Operator;
1307
1308	TemplateIdAnnotation *TemplateId = TemplateIdAnnotation::Create(
1309	TemplateKWLoc, TemplateNameLoc, Name: TemplateII, OperatorKind: OpKind, OpaqueTemplateName: Template, TemplateKind: TNK,
1310	LAngleLoc, RAngleLoc, TemplateArgs, ArgsInvalid, CleanupList&: TemplateIds);
1311
1312	Tok.setAnnotationValue(TemplateId);
1313	if (TemplateKWLoc.isValid())
1314	Tok.setLocation(TemplateKWLoc);
1315	else
1316	Tok.setLocation(TemplateNameLoc);
1317	}
1318
1319	// Common fields for the annotation token
1320	Tok.setAnnotationEndLoc(RAngleLoc);
1321
1322	// In case the tokens were cached, have Preprocessor replace them with the
1323	// annotation token.
1324	PP.AnnotateCachedTokens(Tok);
1325	return false;
1326	}
1327
1328	/// Replaces a template-id annotation token with a type
1329	/// annotation token.
1330	///
1331	/// If there was a failure when forming the type from the template-id,
1332	/// a type annotation token will still be created, but will have a
1333	/// NULL type pointer to signify an error.
1334	///
1335	/// \param SS The scope specifier appearing before the template-id, if any.
1336	///
1337	/// \param AllowImplicitTypename whether this is a context where T::type
1338	/// denotes a dependent type.
1339	/// \param IsClassName Is this template-id appearing in a context where we
1340	/// know it names a class, such as in an elaborated-type-specifier or
1341	/// base-specifier? ('typename' and 'template' are unneeded and disallowed
1342	/// in those contexts.)
1343	void Parser::AnnotateTemplateIdTokenAsType(
1344	CXXScopeSpec &SS, ImplicitTypenameContext AllowImplicitTypename,
1345	bool IsClassName) {
1346	assert(Tok.is(tok::annot_template_id) && "Requires template-id tokens");
1347
1348	TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(tok: Tok);
1349	assert(TemplateId->mightBeType() &&
1350	"Only works for type and dependent templates");
1351
1352	ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
1353	TemplateId->NumArgs);
1354
1355	TypeResult Type =
1356	TemplateId->isInvalid()
1357	? TypeError()
1358	: Actions.ActOnTemplateIdType(
1359	S: getCurScope(), SS, TemplateKWLoc: TemplateId->TemplateKWLoc,
1360	Template: TemplateId->Template, TemplateII: TemplateId->Name,
1361	TemplateIILoc: TemplateId->TemplateNameLoc, LAngleLoc: TemplateId->LAngleLoc,
1362	TemplateArgs: TemplateArgsPtr, RAngleLoc: TemplateId->RAngleLoc,
1363	/*IsCtorOrDtorName=*/false, IsClassName, AllowImplicitTypename);
1364	// Create the new "type" annotation token.
1365	Tok.setKind(tok::annot_typename);
1366	setTypeAnnotation(Tok, T: Type);
1367	if (SS.isNotEmpty()) // it was a C++ qualified type name.
1368	Tok.setLocation(SS.getBeginLoc());
1369	// End location stays the same
1370
1371	// Replace the template-id annotation token, and possible the scope-specifier
1372	// that precedes it, with the typename annotation token.
1373	PP.AnnotateCachedTokens(Tok);
1374	}
1375
1376	/// Determine whether the given token can end a template argument.
1377	static bool isEndOfTemplateArgument(Token Tok) {
1378	// FIXME: Handle '>>>'.
1379	return Tok.isOneOf(K1: tok::comma, Ks: tok::greater, Ks: tok::greatergreater,
1380	Ks: tok::greatergreatergreater);
1381	}
1382
1383	/// Parse a C++ template template argument.
1384	ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
1385	if (!Tok.is(K: tok::identifier) && !Tok.is(K: tok::coloncolon) &&
1386	!Tok.is(K: tok::annot_cxxscope))
1387	return ParsedTemplateArgument();
1388
1389	// C++0x [temp.arg.template]p1:
1390	// A template-argument for a template template-parameter shall be the name
1391	// of a class template or an alias template, expressed as id-expression.
1392	//
1393	// We parse an id-expression that refers to a class template or alias
1394	// template. The grammar we parse is:
1395	//
1396	// nested-name-specifier[opt] template[opt] identifier ...[opt]
1397	//
1398	// followed by a token that terminates a template argument, such as ',',
1399	// '>', or (in some cases) '>>'.
1400	CXXScopeSpec SS; // nested-name-specifier, if present
1401	ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
1402	/*ObjectHasErrors=*/false,
1403	/*EnteringContext=*/false);
1404
1405	ParsedTemplateArgument Result;
1406	SourceLocation EllipsisLoc;
1407	if (SS.isSet() && Tok.is(K: tok::kw_template)) {
1408	// Parse the optional 'template' keyword following the
1409	// nested-name-specifier.
1410	SourceLocation TemplateKWLoc = ConsumeToken();
1411
1412	if (Tok.is(K: tok::identifier)) {
1413	// We appear to have a dependent template name.
1414	UnqualifiedId Name;
1415	Name.setIdentifier(Id: Tok.getIdentifierInfo(), IdLoc: Tok.getLocation());
1416	ConsumeToken(); // the identifier
1417
1418	TryConsumeToken(Expected: tok::ellipsis, Loc&: EllipsisLoc);
1419
1420	// If the next token signals the end of a template argument, then we have
1421	// a (possibly-dependent) template name that could be a template template
1422	// argument.
1423	TemplateTy Template;
1424	if (isEndOfTemplateArgument(Tok) &&
1425	Actions.ActOnTemplateName(S: getCurScope(), SS, TemplateKWLoc, Name,
1426	/*ObjectType=*/nullptr,
1427	/*EnteringContext=*/false, Template))
1428	Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1429	}
1430	} else if (Tok.is(K: tok::identifier)) {
1431	// We may have a (non-dependent) template name.
1432	TemplateTy Template;
1433	UnqualifiedId Name;
1434	Name.setIdentifier(Id: Tok.getIdentifierInfo(), IdLoc: Tok.getLocation());
1435	ConsumeToken(); // the identifier
1436
1437	TryConsumeToken(Expected: tok::ellipsis, Loc&: EllipsisLoc);
1438
1439	if (isEndOfTemplateArgument(Tok)) {
1440	bool MemberOfUnknownSpecialization;
1441	TemplateNameKind TNK = Actions.isTemplateName(
1442	S: getCurScope(), SS,
1443	/*hasTemplateKeyword=*/false, Name,
1444	/*ObjectType=*/nullptr,
1445	/*EnteringContext=*/false, Template, MemberOfUnknownSpecialization);
1446	if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
1447	// We have an id-expression that refers to a class template or
1448	// (C++0x) alias template.
1449	Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1450	}
1451	}
1452	}
1453
1454	// If this is a pack expansion, build it as such.
1455	if (EllipsisLoc.isValid() && !Result.isInvalid())
1456	Result = Actions.ActOnPackExpansion(Arg: Result, EllipsisLoc);
1457
1458	return Result;
1459	}
1460
1461	/// ParseTemplateArgument - Parse a C++ template argument (C++ [temp.names]).
1462	///
1463	/// template-argument: [C++ 14.2]
1464	/// constant-expression
1465	/// type-id
1466	/// id-expression
1467	/// braced-init-list [C++26, DR]
1468	///
1469	ParsedTemplateArgument Parser::ParseTemplateArgument() {
1470	// C++ [temp.arg]p2:
1471	// In a template-argument, an ambiguity between a type-id and an
1472	// expression is resolved to a type-id, regardless of the form of
1473	// the corresponding template-parameter.
1474	//
1475	// Therefore, we initially try to parse a type-id - and isCXXTypeId might look
1476	// up and annotate an identifier as an id-expression during disambiguation,
1477	// so enter the appropriate context for a constant expression template
1478	// argument before trying to disambiguate.
1479
1480	EnterExpressionEvaluationContext EnterConstantEvaluated(
1481	Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated,
1482	/*LambdaContextDecl=*/nullptr,
1483	/*ExprContext=*/Sema::ExpressionEvaluationContextRecord::EK_TemplateArgument);
1484	if (isCXXTypeId(Context: TypeIdAsTemplateArgument)) {
1485	TypeResult TypeArg = ParseTypeName(
1486	/*Range=*/nullptr, Context: DeclaratorContext::TemplateArg);
1487	return Actions.ActOnTemplateTypeArgument(ParsedType: TypeArg);
1488	}
1489
1490	// Try to parse a template template argument.
1491	{
1492	TentativeParsingAction TPA(*this);
1493
1494	ParsedTemplateArgument TemplateTemplateArgument
1495	= ParseTemplateTemplateArgument();
1496	if (!TemplateTemplateArgument.isInvalid()) {
1497	TPA.Commit();
1498	return TemplateTemplateArgument;
1499	}
1500
1501	// Revert this tentative parse to parse a non-type template argument.
1502	TPA.Revert();
1503	}
1504
1505	// Parse a non-type template argument.
1506	ExprResult ExprArg;
1507	SourceLocation Loc = Tok.getLocation();
1508	if (getLangOpts().CPlusPlus11 && Tok.is(K: tok::l_brace))
1509	ExprArg = ParseBraceInitializer();
1510	else
1511	ExprArg = ParseConstantExpressionInExprEvalContext(isTypeCast: MaybeTypeCast);
1512	if (ExprArg.isInvalid() || !ExprArg.get()) {
1513	return ParsedTemplateArgument();
1514	}
1515
1516	return ParsedTemplateArgument(ParsedTemplateArgument::NonType,
1517	ExprArg.get(), Loc);
1518	}
1519
1520	/// ParseTemplateArgumentList - Parse a C++ template-argument-list
1521	/// (C++ [temp.names]). Returns true if there was an error.
1522	///
1523	/// template-argument-list: [C++ 14.2]
1524	/// template-argument
1525	/// template-argument-list ',' template-argument
1526	///
1527	/// \param Template is only used for code completion, and may be null.
1528	bool Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs,
1529	TemplateTy Template,
1530	SourceLocation OpenLoc) {
1531
1532	ColonProtectionRAIIObject ColonProtection(*this, false);
1533
1534	auto RunSignatureHelp = [&] {
1535	if (!Template)
1536	return QualType();
1537	CalledSignatureHelp = true;
1538	return Actions.ProduceTemplateArgumentSignatureHelp(Template, TemplateArgs,
1539	LAngleLoc: OpenLoc);
1540	};
1541
1542	do {
1543	PreferredType.enterFunctionArgument(Tok.getLocation(), RunSignatureHelp);
1544	ParsedTemplateArgument Arg = ParseTemplateArgument();
1545	SourceLocation EllipsisLoc;
1546	if (TryConsumeToken(Expected: tok::ellipsis, Loc&: EllipsisLoc))
1547	Arg = Actions.ActOnPackExpansion(Arg, EllipsisLoc);
1548
1549	if (Arg.isInvalid()) {
1550	if (PP.isCodeCompletionReached() && !CalledSignatureHelp)
1551	RunSignatureHelp();
1552	return true;
1553	}
1554
1555	// Save this template argument.
1556	TemplateArgs.push_back(Elt: Arg);
1557
1558	// If the next token is a comma, consume it and keep reading
1559	// arguments.
1560	} while (TryConsumeToken(Expected: tok::comma));
1561
1562	return false;
1563	}
1564
1565	/// Parse a C++ explicit template instantiation
1566	/// (C++ [temp.explicit]).
1567	///
1568	/// explicit-instantiation:
1569	/// 'extern' [opt] 'template' declaration
1570	///
1571	/// Note that the 'extern' is a GNU extension and C++11 feature.
1572	Parser::DeclGroupPtrTy Parser::ParseExplicitInstantiation(
1573	DeclaratorContext Context, SourceLocation ExternLoc,
1574	SourceLocation TemplateLoc, SourceLocation &DeclEnd,
1575	ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
1576	// This isn't really required here.
1577	ParsingDeclRAIIObject
1578	ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
1579	ParsedTemplateInfo TemplateInfo(ExternLoc, TemplateLoc);
1580	return ParseDeclarationAfterTemplate(
1581	Context, TemplateInfo, DiagsFromTParams&: ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
1582	}
1583
1584	SourceRange Parser::ParsedTemplateInfo::getSourceRange() const {
1585	if (TemplateParams)
1586	return getTemplateParamsRange(Params: TemplateParams->data(),
1587	NumParams: TemplateParams->size());
1588
1589	SourceRange R(TemplateLoc);
1590	if (ExternLoc.isValid())
1591	R.setBegin(ExternLoc);
1592	return R;
1593	}
1594
1595	void Parser::LateTemplateParserCallback(void *P, LateParsedTemplate &LPT) {
1596	((Parser *)P)->ParseLateTemplatedFuncDef(LPT);
1597	}
1598
1599	/// Late parse a C++ function template in Microsoft mode.
1600	void Parser::ParseLateTemplatedFuncDef(LateParsedTemplate &LPT) {
1601	if (!LPT.D)
1602	return;
1603
1604	// Destroy TemplateIdAnnotations when we're done, if possible.
1605	DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(*this);
1606
1607	// Get the FunctionDecl.
1608	FunctionDecl *FunD = LPT.D->getAsFunction();
1609	// Track template parameter depth.
1610	TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
1611
1612	// To restore the context after late parsing.
1613	Sema::ContextRAII GlobalSavedContext(
1614	Actions, Actions.Context.getTranslationUnitDecl());
1615
1616	MultiParseScope Scopes(*this);
1617
1618	// Get the list of DeclContexts to reenter.
1619	SmallVector<DeclContext*, 4> DeclContextsToReenter;
1620	for (DeclContext *DC = FunD; DC && !DC->isTranslationUnit();
1621	DC = DC->getLexicalParent())
1622	DeclContextsToReenter.push_back(Elt: DC);
1623
1624	// Reenter scopes from outermost to innermost.
1625	for (DeclContext *DC : reverse(C&: DeclContextsToReenter)) {
1626	CurTemplateDepthTracker.addDepth(
1627	D: ReenterTemplateScopes(S&: Scopes, D: cast<Decl>(Val: DC)));
1628	Scopes.Enter(ScopeFlags: Scope::DeclScope);
1629	// We'll reenter the function context itself below.
1630	if (DC != FunD)
1631	Actions.PushDeclContext(S: Actions.getCurScope(), DC);
1632	}
1633
1634	// Parsing should occur with empty FP pragma stack and FP options used in the
1635	// point of the template definition.
1636	Sema::FpPragmaStackSaveRAII SavedStack(Actions);
1637	Actions.resetFPOptions(FPO: LPT.FPO);
1638
1639	assert(!LPT.Toks.empty() && "Empty body!");
1640
1641	// Append the current token at the end of the new token stream so that it
1642	// doesn't get lost.
1643	LPT.Toks.push_back(Elt: Tok);
1644	PP.EnterTokenStream(Toks: LPT.Toks, DisableMacroExpansion: true, /*IsReinject*/true);
1645
1646	// Consume the previously pushed token.
1647	ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
1648	assert(Tok.isOneOf(tok::l_brace, tok::colon, tok::kw_try) &&
1649	"Inline method not starting with '{', ':' or 'try'");
1650
1651	// Parse the method body. Function body parsing code is similar enough
1652	// to be re-used for method bodies as well.
1653	ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope |
1654	Scope::CompoundStmtScope);
1655
1656	// Recreate the containing function DeclContext.
1657	Sema::ContextRAII FunctionSavedContext(Actions, FunD->getLexicalParent());
1658
1659	Actions.ActOnStartOfFunctionDef(getCurScope(), FunD);
1660
1661	if (Tok.is(K: tok::kw_try)) {
1662	ParseFunctionTryBlock(Decl: LPT.D, BodyScope&: FnScope);
1663	} else {
1664	if (Tok.is(K: tok::colon))
1665	ParseConstructorInitializer(ConstructorDecl: LPT.D);
1666	else
1667	Actions.ActOnDefaultCtorInitializers(CDtorDecl: LPT.D);
1668
1669	if (Tok.is(K: tok::l_brace)) {
1670	assert((!isa<FunctionTemplateDecl>(LPT.D) ||
1671	cast<FunctionTemplateDecl>(LPT.D)
1672	->getTemplateParameters()
1673	->getDepth() == TemplateParameterDepth - 1) &&
1674	"TemplateParameterDepth should be greater than the depth of "
1675	"current template being instantiated!");
1676	ParseFunctionStatementBody(Decl: LPT.D, BodyScope&: FnScope);
1677	Actions.UnmarkAsLateParsedTemplate(FD: FunD);
1678	} else
1679	Actions.ActOnFinishFunctionBody(Decl: LPT.D, Body: nullptr);
1680	}
1681	}
1682
1683	/// Lex a delayed template function for late parsing.
1684	void Parser::LexTemplateFunctionForLateParsing(CachedTokens &Toks) {
1685	tok::TokenKind kind = Tok.getKind();
1686	if (!ConsumeAndStoreFunctionPrologue(Toks)) {
1687	// Consume everything up to (and including) the matching right brace.
1688	ConsumeAndStoreUntil(T1: tok::r_brace, Toks, /*StopAtSemi=*/false);
1689	}
1690
1691	// If we're in a function-try-block, we need to store all the catch blocks.
1692	if (kind == tok::kw_try) {
1693	while (Tok.is(K: tok::kw_catch)) {
1694	ConsumeAndStoreUntil(T1: tok::l_brace, Toks, /*StopAtSemi=*/false);
1695	ConsumeAndStoreUntil(T1: tok::r_brace, Toks, /*StopAtSemi=*/false);
1696	}
1697	}
1698	}
1699
1700	/// We've parsed something that could plausibly be intended to be a template
1701	/// name (\p LHS) followed by a '<' token, and the following code can't possibly
1702	/// be an expression. Determine if this is likely to be a template-id and if so,
1703	/// diagnose it.
1704	bool Parser::diagnoseUnknownTemplateId(ExprResult LHS, SourceLocation Less) {
1705	TentativeParsingAction TPA(*this);
1706	// FIXME: We could look at the token sequence in a lot more detail here.
1707	if (SkipUntil(T1: tok::greater, T2: tok::greatergreater, T3: tok::greatergreatergreater,
1708	Flags: StopAtSemi | StopBeforeMatch)) {
1709	TPA.Commit();
1710
1711	SourceLocation Greater;
1712	ParseGreaterThanInTemplateList(LAngleLoc: Less, RAngleLoc&: Greater, ConsumeLastToken: true, ObjCGenericList: false);
1713	Actions.diagnoseExprIntendedAsTemplateName(S: getCurScope(), TemplateName: LHS,
1714	Less, Greater);
1715	return true;
1716	}
1717
1718	// There's no matching '>' token, this probably isn't supposed to be
1719	// interpreted as a template-id. Parse it as an (ill-formed) comparison.
1720	TPA.Revert();
1721	return false;
1722	}
1723
1724	void Parser::checkPotentialAngleBracket(ExprResult &PotentialTemplateName) {
1725	assert(Tok.is(tok::less) && "not at a potential angle bracket");
1726
1727	bool DependentTemplateName = false;
1728	if (!Actions.mightBeIntendedToBeTemplateName(E: PotentialTemplateName,
1729	Dependent&: DependentTemplateName))
1730	return;
1731
1732	// OK, this might be a name that the user intended to be parsed as a
1733	// template-name, followed by a '<' token. Check for some easy cases.
1734
1735	// If we have potential_template<>, then it's supposed to be a template-name.
1736	if (NextToken().is(K: tok::greater) ||
1737	(getLangOpts().CPlusPlus11 &&
1738	NextToken().isOneOf(K1: tok::greatergreater, K2: tok::greatergreatergreater))) {
1739	SourceLocation Less = ConsumeToken();
1740	SourceLocation Greater;
1741	ParseGreaterThanInTemplateList(LAngleLoc: Less, RAngleLoc&: Greater, ConsumeLastToken: true, ObjCGenericList: false);
1742	Actions.diagnoseExprIntendedAsTemplateName(
1743	S: getCurScope(), TemplateName: PotentialTemplateName, Less, Greater);
1744	// FIXME: Perform error recovery.
1745	PotentialTemplateName = ExprError();
1746	return;
1747	}
1748
1749	// If we have 'potential_template<type-id', assume it's supposed to be a
1750	// template-name if there's a matching '>' later on.
1751	{
1752	// FIXME: Avoid the tentative parse when NextToken() can't begin a type.
1753	TentativeParsingAction TPA(*this);
1754	SourceLocation Less = ConsumeToken();
1755	if (isTypeIdUnambiguously() &&
1756	diagnoseUnknownTemplateId(LHS: PotentialTemplateName, Less)) {
1757	TPA.Commit();
1758	// FIXME: Perform error recovery.
1759	PotentialTemplateName = ExprError();
1760	return;
1761	}
1762	TPA.Revert();
1763	}
1764
1765	// Otherwise, remember that we saw this in case we see a potentially-matching
1766	// '>' token later on.
1767	AngleBracketTracker::Priority Priority =
1768	(DependentTemplateName ? AngleBracketTracker::DependentName
1769	: AngleBracketTracker::PotentialTypo) |
1770	(Tok.hasLeadingSpace() ? AngleBracketTracker::SpaceBeforeLess
1771	: AngleBracketTracker::NoSpaceBeforeLess);
1772	AngleBrackets.add(P&: *this, TemplateName: PotentialTemplateName.get(), LessLoc: Tok.getLocation(),
1773	Prio: Priority);
1774	}
1775
1776	bool Parser::checkPotentialAngleBracketDelimiter(
1777	const AngleBracketTracker::Loc &LAngle, const Token &OpToken) {
1778	// If a comma in an expression context is followed by a type that can be a
1779	// template argument and cannot be an expression, then this is ill-formed,
1780	// but might be intended to be part of a template-id.
1781	if (OpToken.is(K: tok::comma) && isTypeIdUnambiguously() &&
1782	diagnoseUnknownTemplateId(LHS: LAngle.TemplateName, Less: LAngle.LessLoc)) {
1783	AngleBrackets.clear(P&: *this);
1784	return true;
1785	}
1786
1787	// If a context that looks like a template-id is followed by '()', then
1788	// this is ill-formed, but might be intended to be a template-id
1789	// followed by '()'.
1790	if (OpToken.is(K: tok::greater) && Tok.is(K: tok::l_paren) &&
1791	NextToken().is(K: tok::r_paren)) {
1792	Actions.diagnoseExprIntendedAsTemplateName(
1793	S: getCurScope(), TemplateName: LAngle.TemplateName, Less: LAngle.LessLoc,
1794	Greater: OpToken.getLocation());
1795	AngleBrackets.clear(P&: *this);
1796	return true;
1797	}
1798
1799	// After a '>' (etc), we're no longer potentially in a construct that's
1800	// intended to be treated as a template-id.
1801	if (OpToken.is(K: tok::greater) ||
1802	(getLangOpts().CPlusPlus11 &&
1803	OpToken.isOneOf(K1: tok::greatergreater, K2: tok::greatergreatergreater)))
1804	AngleBrackets.clear(P&: *this);
1805	return false;
1806	}
1807