1	//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
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 statements.
10	//
11	//===----------------------------------------------------------------------===//
12
13	#include "clang/AST/ASTContext.h"
14	#include "clang/AST/ASTDiagnostic.h"
15	#include "clang/AST/ASTLambda.h"
16	#include "clang/AST/CXXInheritance.h"
17	#include "clang/AST/CharUnits.h"
18	#include "clang/AST/DeclObjC.h"
19	#include "clang/AST/EvaluatedExprVisitor.h"
20	#include "clang/AST/ExprCXX.h"
21	#include "clang/AST/ExprObjC.h"
22	#include "clang/AST/IgnoreExpr.h"
23	#include "clang/AST/RecursiveASTVisitor.h"
24	#include "clang/AST/StmtCXX.h"
25	#include "clang/AST/StmtObjC.h"
26	#include "clang/AST/TypeLoc.h"
27	#include "clang/AST/TypeOrdering.h"
28	#include "clang/Basic/TargetInfo.h"
29	#include "clang/Lex/Preprocessor.h"
30	#include "clang/Sema/EnterExpressionEvaluationContext.h"
31	#include "clang/Sema/Initialization.h"
32	#include "clang/Sema/Lookup.h"
33	#include "clang/Sema/Ownership.h"
34	#include "clang/Sema/Scope.h"
35	#include "clang/Sema/ScopeInfo.h"
36	#include "clang/Sema/SemaInternal.h"
37	#include "llvm/ADT/ArrayRef.h"
38	#include "llvm/ADT/DenseMap.h"
39	#include "llvm/ADT/STLExtras.h"
40	#include "llvm/ADT/SmallPtrSet.h"
41	#include "llvm/ADT/SmallString.h"
42	#include "llvm/ADT/SmallVector.h"
43	#include "llvm/ADT/StringExtras.h"
44
45	using namespace clang;
46	using namespace sema;
47
48	StmtResult Sema::ActOnExprStmt(ExprResult FE, bool DiscardedValue) {
49	if (FE.isInvalid())
50	return StmtError();
51
52	FE = ActOnFinishFullExpr(Expr: FE.get(), CC: FE.get()->getExprLoc(), DiscardedValue);
53	if (FE.isInvalid())
54	return StmtError();
55
56	// C99 6.8.3p2: The expression in an expression statement is evaluated as a
57	// void expression for its side effects. Conversion to void allows any
58	// operand, even incomplete types.
59
60	// Same thing in for stmt first clause (when expr) and third clause.
61	return StmtResult(FE.getAs<Stmt>());
62	}
63
64
65	StmtResult Sema::ActOnExprStmtError() {
66	DiscardCleanupsInEvaluationContext();
67	return StmtError();
68	}
69
70	StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc,
71	bool HasLeadingEmptyMacro) {
72	return new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro);
73	}
74
75	StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc,
76	SourceLocation EndLoc) {
77	DeclGroupRef DG = dg.get();
78
79	// If we have an invalid decl, just return an error.
80	if (DG.isNull()) return StmtError();
81
82	return new (Context) DeclStmt(DG, StartLoc, EndLoc);
83	}
84
85	void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
86	DeclGroupRef DG = dg.get();
87
88	// If we don't have a declaration, or we have an invalid declaration,
89	// just return.
90	if (DG.isNull() || !DG.isSingleDecl())
91	return;
92
93	Decl *decl = DG.getSingleDecl();
94	if (!decl || decl->isInvalidDecl())
95	return;
96
97	// Only variable declarations are permitted.
98	VarDecl *var = dyn_cast<VarDecl>(Val: decl);
99	if (!var) {
100	Diag(decl->getLocation(), diag::err_non_variable_decl_in_for);
101	decl->setInvalidDecl();
102	return;
103	}
104
105	// foreach variables are never actually initialized in the way that
106	// the parser came up with.
107	var->setInit(nullptr);
108
109	// In ARC, we don't need to retain the iteration variable of a fast
110	// enumeration loop. Rather than actually trying to catch that
111	// during declaration processing, we remove the consequences here.
112	if (getLangOpts().ObjCAutoRefCount) {
113	QualType type = var->getType();
114
115	// Only do this if we inferred the lifetime. Inferred lifetime
116	// will show up as a local qualifier because explicit lifetime
117	// should have shown up as an AttributedType instead.
118	if (type.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong) {
119	// Add 'const' and mark the variable as pseudo-strong.
120	var->setType(type.withConst());
121	var->setARCPseudoStrong(true);
122	}
123	}
124	}
125
126	/// Diagnose unused comparisons, both builtin and overloaded operators.
127	/// For '==' and '!=', suggest fixits for '=' or '|='.
128	///
129	/// Adding a cast to void (or other expression wrappers) will prevent the
130	/// warning from firing.
131	static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) {
132	SourceLocation Loc;
133	bool CanAssign;
134	enum { Equality, Inequality, Relational, ThreeWay } Kind;
135
136	if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(Val: E)) {
137	if (!Op->isComparisonOp())
138	return false;
139
140	if (Op->getOpcode() == BO_EQ)
141	Kind = Equality;
142	else if (Op->getOpcode() == BO_NE)
143	Kind = Inequality;
144	else if (Op->getOpcode() == BO_Cmp)
145	Kind = ThreeWay;
146	else {
147	assert(Op->isRelationalOp());
148	Kind = Relational;
149	}
150	Loc = Op->getOperatorLoc();
151	CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
152	} else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(Val: E)) {
153	switch (Op->getOperator()) {
154	case OO_EqualEqual:
155	Kind = Equality;
156	break;
157	case OO_ExclaimEqual:
158	Kind = Inequality;
159	break;
160	case OO_Less:
161	case OO_Greater:
162	case OO_GreaterEqual:
163	case OO_LessEqual:
164	Kind = Relational;
165	break;
166	case OO_Spaceship:
167	Kind = ThreeWay;
168	break;
169	default:
170	return false;
171	}
172
173	Loc = Op->getOperatorLoc();
174	CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
175	} else {
176	// Not a typo-prone comparison.
177	return false;
178	}
179
180	// Suppress warnings when the operator, suspicious as it may be, comes from
181	// a macro expansion.
182	if (S.SourceMgr.isMacroBodyExpansion(Loc))
183	return false;
184
185	S.Diag(Loc, diag::warn_unused_comparison)
186	<< (unsigned)Kind << E->getSourceRange();
187
188	// If the LHS is a plausible entity to assign to, provide a fixit hint to
189	// correct common typos.
190	if (CanAssign) {
191	if (Kind == Inequality)
192	S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
193	<< FixItHint::CreateReplacement(Loc, "|=");
194	else if (Kind == Equality)
195	S.Diag(Loc, diag::note_equality_comparison_to_assign)
196	<< FixItHint::CreateReplacement(Loc, "=");
197	}
198
199	return true;
200	}
201
202	static bool DiagnoseNoDiscard(Sema &S, const WarnUnusedResultAttr *A,
203	SourceLocation Loc, SourceRange R1,
204	SourceRange R2, bool IsCtor) {
205	if (!A)
206	return false;
207	StringRef Msg = A->getMessage();
208
209	if (Msg.empty()) {
210	if (IsCtor)
211	return S.Diag(Loc, diag::warn_unused_constructor) << A << R1 << R2;
212	return S.Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
213	}
214
215	if (IsCtor)
216	return S.Diag(Loc, diag::warn_unused_constructor_msg) << A << Msg << R1
217	<< R2;
218	return S.Diag(Loc, diag::warn_unused_result_msg) << A << Msg << R1 << R2;
219	}
220
221	void Sema::DiagnoseUnusedExprResult(const Stmt *S, unsigned DiagID) {
222	if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(Val: S))
223	return DiagnoseUnusedExprResult(S: Label->getSubStmt(), DiagID);
224
225	const Expr *E = dyn_cast_or_null<Expr>(Val: S);
226	if (!E)
227	return;
228
229	// If we are in an unevaluated expression context, then there can be no unused
230	// results because the results aren't expected to be used in the first place.
231	if (isUnevaluatedContext())
232	return;
233
234	SourceLocation ExprLoc = E->IgnoreParenImpCasts()->getExprLoc();
235	// In most cases, we don't want to warn if the expression is written in a
236	// macro body, or if the macro comes from a system header. If the offending
237	// expression is a call to a function with the warn_unused_result attribute,
238	// we warn no matter the location. Because of the order in which the various
239	// checks need to happen, we factor out the macro-related test here.
240	bool ShouldSuppress =
241	SourceMgr.isMacroBodyExpansion(Loc: ExprLoc) ||
242	SourceMgr.isInSystemMacro(loc: ExprLoc);
243
244	const Expr *WarnExpr;
245	SourceLocation Loc;
246	SourceRange R1, R2;
247	if (!E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Ctx&: Context))
248	return;
249
250	// If this is a GNU statement expression expanded from a macro, it is probably
251	// unused because it is a function-like macro that can be used as either an
252	// expression or statement. Don't warn, because it is almost certainly a
253	// false positive.
254	if (isa<StmtExpr>(Val: E) && Loc.isMacroID())
255	return;
256
257	// Check if this is the UNREFERENCED_PARAMETER from the Microsoft headers.
258	// That macro is frequently used to suppress "unused parameter" warnings,
259	// but its implementation makes clang's -Wunused-value fire. Prevent this.
260	if (isa<ParenExpr>(Val: E->IgnoreImpCasts()) && Loc.isMacroID()) {
261	SourceLocation SpellLoc = Loc;
262	if (findMacroSpelling(loc&: SpellLoc, name: "UNREFERENCED_PARAMETER"))
263	return;
264	}
265
266	// Okay, we have an unused result. Depending on what the base expression is,
267	// we might want to make a more specific diagnostic. Check for one of these
268	// cases now.
269	if (const FullExpr *Temps = dyn_cast<FullExpr>(Val: E))
270	E = Temps->getSubExpr();
271	if (const CXXBindTemporaryExpr *TempExpr = dyn_cast<CXXBindTemporaryExpr>(Val: E))
272	E = TempExpr->getSubExpr();
273
274	if (DiagnoseUnusedComparison(S&: *this, E))
275	return;
276
277	E = WarnExpr;
278	if (const auto *Cast = dyn_cast<CastExpr>(Val: E))
279	if (Cast->getCastKind() == CK_NoOp ||
280	Cast->getCastKind() == CK_ConstructorConversion)
281	E = Cast->getSubExpr()->IgnoreImpCasts();
282
283	if (const CallExpr *CE = dyn_cast<CallExpr>(Val: E)) {
284	if (E->getType()->isVoidType())
285	return;
286
287	if (DiagnoseNoDiscard(*this, cast_or_null<WarnUnusedResultAttr>(
288	CE->getUnusedResultAttr(Context)),
289	Loc, R1, R2, /*isCtor=*/false))
290	return;
291
292	// If the callee has attribute pure, const, or warn_unused_result, warn with
293	// a more specific message to make it clear what is happening. If the call
294	// is written in a macro body, only warn if it has the warn_unused_result
295	// attribute.
296	if (const Decl *FD = CE->getCalleeDecl()) {
297	if (ShouldSuppress)
298	return;
299	if (FD->hasAttr<PureAttr>()) {
300	Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
301	return;
302	}
303	if (FD->hasAttr<ConstAttr>()) {
304	Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
305	return;
306	}
307	}
308	} else if (const auto *CE = dyn_cast<CXXConstructExpr>(Val: E)) {
309	if (const CXXConstructorDecl *Ctor = CE->getConstructor()) {
310	const auto *A = Ctor->getAttr<WarnUnusedResultAttr>();
311	A = A ? A : Ctor->getParent()->getAttr<WarnUnusedResultAttr>();
312	if (DiagnoseNoDiscard(*this, A, Loc, R1, R2, /*isCtor=*/true))
313	return;
314	}
315	} else if (const auto *ILE = dyn_cast<InitListExpr>(Val: E)) {
316	if (const TagDecl *TD = ILE->getType()->getAsTagDecl()) {
317
318	if (DiagnoseNoDiscard(*this, TD->getAttr<WarnUnusedResultAttr>(), Loc, R1,
319	R2, /*isCtor=*/false))
320	return;
321	}
322	} else if (ShouldSuppress)
323	return;
324
325	E = WarnExpr;
326	if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(Val: E)) {
327	if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) {
328	Diag(Loc, diag::err_arc_unused_init_message) << R1;
329	return;
330	}
331	const ObjCMethodDecl *MD = ME->getMethodDecl();
332	if (MD) {
333	if (DiagnoseNoDiscard(*this, MD->getAttr<WarnUnusedResultAttr>(), Loc, R1,
334	R2, /*isCtor=*/false))
335	return;
336	}
337	} else if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(Val: E)) {
338	const Expr *Source = POE->getSyntacticForm();
339	// Handle the actually selected call of an OpenMP specialized call.
340	if (LangOpts.OpenMP && isa<CallExpr>(Val: Source) &&
341	POE->getNumSemanticExprs() == 1 &&
342	isa<CallExpr>(Val: POE->getSemanticExpr(index: 0)))
343	return DiagnoseUnusedExprResult(POE->getSemanticExpr(index: 0), DiagID);
344	if (isa<ObjCSubscriptRefExpr>(Source))
345	DiagID = diag::warn_unused_container_subscript_expr;
346	else if (isa<ObjCPropertyRefExpr>(Source))
347	DiagID = diag::warn_unused_property_expr;
348	} else if (const CXXFunctionalCastExpr *FC
349	= dyn_cast<CXXFunctionalCastExpr>(Val: E)) {
350	const Expr *E = FC->getSubExpr();
351	if (const CXXBindTemporaryExpr *TE = dyn_cast<CXXBindTemporaryExpr>(Val: E))
352	E = TE->getSubExpr();
353	if (isa<CXXTemporaryObjectExpr>(Val: E))
354	return;
355	if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(Val: E))
356	if (const CXXRecordDecl *RD = CE->getType()->getAsCXXRecordDecl())
357	if (!RD->getAttr<WarnUnusedAttr>())
358	return;
359	}
360	// Diagnose "(void*) blah" as a typo for "(void) blah".
361	else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(Val: E)) {
362	TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
363	QualType T = TI->getType();
364
365	// We really do want to use the non-canonical type here.
366	if (T == Context.VoidPtrTy) {
367	PointerTypeLoc TL = TI->getTypeLoc().castAs<PointerTypeLoc>();
368
369	Diag(Loc, diag::warn_unused_voidptr)
370	<< FixItHint::CreateRemoval(TL.getStarLoc());
371	return;
372	}
373	}
374
375	// Tell the user to assign it into a variable to force a volatile load if this
376	// isn't an array.
377	if (E->isGLValue() && E->getType().isVolatileQualified() &&
378	!E->getType()->isArrayType()) {
379	Diag(Loc, diag::warn_unused_volatile) << R1 << R2;
380	return;
381	}
382
383	// Do not diagnose use of a comma operator in a SFINAE context because the
384	// type of the left operand could be used for SFINAE, so technically it is
385	// *used*.
386	if (DiagID != diag::warn_unused_comma_left_operand || !isSFINAEContext())
387	DiagIfReachable(Loc, Stmts: S ? llvm::ArrayRef(S) : std::nullopt,
388	PD: PDiag(DiagID) << R1 << R2);
389	}
390
391	void Sema::ActOnStartOfCompoundStmt(bool IsStmtExpr) {
392	PushCompoundScope(IsStmtExpr);
393	}
394
395	void Sema::ActOnAfterCompoundStatementLeadingPragmas() {
396	if (getCurFPFeatures().isFPConstrained()) {
397	FunctionScopeInfo *FSI = getCurFunction();
398	assert(FSI);
399	FSI->setUsesFPIntrin();
400	}
401	}
402
403	void Sema::ActOnFinishOfCompoundStmt() {
404	PopCompoundScope();
405	}
406
407	sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
408	return getCurFunction()->CompoundScopes.back();
409	}
410
411	StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
412	ArrayRef<Stmt *> Elts, bool isStmtExpr) {
413	const unsigned NumElts = Elts.size();
414
415	// If we're in C mode, check that we don't have any decls after stmts. If
416	// so, emit an extension diagnostic in C89 and potentially a warning in later
417	// versions.
418	const unsigned MixedDeclsCodeID = getLangOpts().C99
419	? diag::warn_mixed_decls_code
420	: diag::ext_mixed_decls_code;
421	if (!getLangOpts().CPlusPlus && !Diags.isIgnored(DiagID: MixedDeclsCodeID, Loc: L)) {
422	// Note that __extension__ can be around a decl.
423	unsigned i = 0;
424	// Skip over all declarations.
425	for (; i != NumElts && isa<DeclStmt>(Val: Elts[i]); ++i)
426	/*empty*/;
427
428	// We found the end of the list or a statement. Scan for another declstmt.
429	for (; i != NumElts && !isa<DeclStmt>(Val: Elts[i]); ++i)
430	/*empty*/;
431
432	if (i != NumElts) {
433	Decl *D = *cast<DeclStmt>(Val: Elts[i])->decl_begin();
434	Diag(Loc: D->getLocation(), DiagID: MixedDeclsCodeID);
435	}
436	}
437
438	// Check for suspicious empty body (null statement) in `for' and `while'
439	// statements. Don't do anything for template instantiations, this just adds
440	// noise.
441	if (NumElts != 0 && !CurrentInstantiationScope &&
442	getCurCompoundScope().HasEmptyLoopBodies) {
443	for (unsigned i = 0; i != NumElts - 1; ++i)
444	DiagnoseEmptyLoopBody(S: Elts[i], PossibleBody: Elts[i + 1]);
445	}
446
447	// Calculate difference between FP options in this compound statement and in
448	// the enclosing one. If this is a function body, take the difference against
449	// default options. In this case the difference will indicate options that are
450	// changed upon entry to the statement.
451	FPOptions FPO = (getCurFunction()->CompoundScopes.size() == 1)
452	? FPOptions(getLangOpts())
453	: getCurCompoundScope().InitialFPFeatures;
454	FPOptionsOverride FPDiff = getCurFPFeatures().getChangesFrom(Base: FPO);
455
456	return CompoundStmt::Create(C: Context, Stmts: Elts, FPFeatures: FPDiff, LB: L, RB: R);
457	}
458
459	ExprResult
460	Sema::ActOnCaseExpr(SourceLocation CaseLoc, ExprResult Val) {
461	if (!Val.get())
462	return Val;
463
464	if (DiagnoseUnexpandedParameterPack(E: Val.get()))
465	return ExprError();
466
467	// If we're not inside a switch, let the 'case' statement handling diagnose
468	// this. Just clean up after the expression as best we can.
469	if (getCurFunction()->SwitchStack.empty())
470	return ActOnFinishFullExpr(Expr: Val.get(), CC: Val.get()->getExprLoc(), DiscardedValue: false,
471	IsConstexpr: getLangOpts().CPlusPlus11);
472
473	Expr *CondExpr =
474	getCurFunction()->SwitchStack.back().getPointer()->getCond();
475	if (!CondExpr)
476	return ExprError();
477	QualType CondType = CondExpr->getType();
478
479	auto CheckAndFinish = [&](Expr *E) {
480	if (CondType->isDependentType() || E->isTypeDependent())
481	return ExprResult(E);
482
483	if (getLangOpts().CPlusPlus11) {
484	// C++11 [stmt.switch]p2: the constant-expression shall be a converted
485	// constant expression of the promoted type of the switch condition.
486	llvm::APSInt TempVal;
487	return CheckConvertedConstantExpression(From: E, T: CondType, Value&: TempVal,
488	CCE: CCEK_CaseValue);
489	}
490
491	ExprResult ER = E;
492	if (!E->isValueDependent())
493	ER = VerifyIntegerConstantExpression(E, CanFold: AllowFold);
494	if (!ER.isInvalid())
495	ER = DefaultLvalueConversion(E: ER.get());
496	if (!ER.isInvalid())
497	ER = ImpCastExprToType(E: ER.get(), Type: CondType, CK: CK_IntegralCast);
498	if (!ER.isInvalid())
499	ER = ActOnFinishFullExpr(Expr: ER.get(), CC: ER.get()->getExprLoc(), DiscardedValue: false);
500	return ER;
501	};
502
503	ExprResult Converted = CorrectDelayedTyposInExpr(
504	ER: Val, /*InitDecl=*/nullptr, /*RecoverUncorrectedTypos=*/false,
505	Filter: CheckAndFinish);
506	if (Converted.get() == Val.get())
507	Converted = CheckAndFinish(Val.get());
508	return Converted;
509	}
510
511	StmtResult
512	Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHSVal,
513	SourceLocation DotDotDotLoc, ExprResult RHSVal,
514	SourceLocation ColonLoc) {
515	assert((LHSVal.isInvalid() || LHSVal.get()) && "missing LHS value");
516	assert((DotDotDotLoc.isInvalid() ? RHSVal.isUnset()
517	: RHSVal.isInvalid() || RHSVal.get()) &&
518	"missing RHS value");
519
520	if (getCurFunction()->SwitchStack.empty()) {
521	Diag(CaseLoc, diag::err_case_not_in_switch);
522	return StmtError();
523	}
524
525	if (LHSVal.isInvalid() || RHSVal.isInvalid()) {
526	getCurFunction()->SwitchStack.back().setInt(true);
527	return StmtError();
528	}
529
530	auto *CS = CaseStmt::Create(Ctx: Context, lhs: LHSVal.get(), rhs: RHSVal.get(),
531	caseLoc: CaseLoc, ellipsisLoc: DotDotDotLoc, colonLoc: ColonLoc);
532	getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(CS);
533	return CS;
534	}
535
536	/// ActOnCaseStmtBody - This installs a statement as the body of a case.
537	void Sema::ActOnCaseStmtBody(Stmt *S, Stmt *SubStmt) {
538	cast<CaseStmt>(Val: S)->setSubStmt(SubStmt);
539	}
540
541	StmtResult
542	Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
543	Stmt *SubStmt, Scope *CurScope) {
544	if (getCurFunction()->SwitchStack.empty()) {
545	Diag(DefaultLoc, diag::err_default_not_in_switch);
546	return SubStmt;
547	}
548
549	DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
550	getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(SC: DS);
551	return DS;
552	}
553
554	StmtResult
555	Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
556	SourceLocation ColonLoc, Stmt *SubStmt) {
557	// If the label was multiply defined, reject it now.
558	if (TheDecl->getStmt()) {
559	Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName();
560	Diag(TheDecl->getLocation(), diag::note_previous_definition);
561	return SubStmt;
562	}
563
564	ReservedIdentifierStatus Status = TheDecl->isReserved(getLangOpts());
565	if (isReservedInAllContexts(Status) &&
566	!Context.getSourceManager().isInSystemHeader(IdentLoc))
567	Diag(IdentLoc, diag::warn_reserved_extern_symbol)
568	<< TheDecl << static_cast<int>(Status);
569
570	// Otherwise, things are good. Fill in the declaration and return it.
571	LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt);
572	TheDecl->setStmt(LS);
573	if (!TheDecl->isGnuLocal()) {
574	TheDecl->setLocStart(IdentLoc);
575	if (!TheDecl->isMSAsmLabel()) {
576	// Don't update the location of MS ASM labels. These will result in
577	// a diagnostic, and changing the location here will mess that up.
578	TheDecl->setLocation(IdentLoc);
579	}
580	}
581	return LS;
582	}
583
584	StmtResult Sema::BuildAttributedStmt(SourceLocation AttrsLoc,
585	ArrayRef<const Attr *> Attrs,
586	Stmt *SubStmt) {
587	// FIXME: this code should move when a planned refactoring around statement
588	// attributes lands.
589	for (const auto *A : Attrs) {
590	if (A->getKind() == attr::MustTail) {
591	if (!checkAndRewriteMustTailAttr(St: SubStmt, MTA: *A)) {
592	return SubStmt;
593	}
594	setFunctionHasMustTail();
595	}
596	}
597
598	return AttributedStmt::Create(C: Context, Loc: AttrsLoc, Attrs, SubStmt);
599	}
600
601	StmtResult Sema::ActOnAttributedStmt(const ParsedAttributes &Attrs,
602	Stmt *SubStmt) {
603	SmallVector<const Attr *, 1> SemanticAttrs;
604	ProcessStmtAttributes(Stmt: SubStmt, InAttrs: Attrs, OutAttrs&: SemanticAttrs);
605	if (!SemanticAttrs.empty())
606	return BuildAttributedStmt(AttrsLoc: Attrs.Range.getBegin(), Attrs: SemanticAttrs, SubStmt);
607	// If none of the attributes applied, that's fine, we can recover by
608	// returning the substatement directly instead of making an AttributedStmt
609	// with no attributes on it.
610	return SubStmt;
611	}
612
613	bool Sema::checkAndRewriteMustTailAttr(Stmt *St, const Attr &MTA) {
614	ReturnStmt *R = cast<ReturnStmt>(Val: St);
615	Expr *E = R->getRetValue();
616
617	if (CurContext->isDependentContext() || (E && E->isInstantiationDependent()))
618	// We have to suspend our check until template instantiation time.
619	return true;
620
621	if (!checkMustTailAttr(St, MTA))
622	return false;
623
624	// FIXME: Replace Expr::IgnoreImplicitAsWritten() with this function.
625	// Currently it does not skip implicit constructors in an initialization
626	// context.
627	auto IgnoreImplicitAsWritten = [](Expr *E) -> Expr * {
628	return IgnoreExprNodes(E, Fns&: IgnoreImplicitAsWrittenSingleStep,
629	Fns&: IgnoreElidableImplicitConstructorSingleStep);
630	};
631
632	// Now that we have verified that 'musttail' is valid here, rewrite the
633	// return value to remove all implicit nodes, but retain parentheses.
634	R->setRetValue(IgnoreImplicitAsWritten(E));
635	return true;
636	}
637
638	bool Sema::checkMustTailAttr(const Stmt *St, const Attr &MTA) {
639	assert(!CurContext->isDependentContext() &&
640	"musttail cannot be checked from a dependent context");
641
642	// FIXME: Add Expr::IgnoreParenImplicitAsWritten() with this definition.
643	auto IgnoreParenImplicitAsWritten = [](const Expr *E) -> const Expr * {
644	return IgnoreExprNodes(E: const_cast<Expr *>(E), Fns&: IgnoreParensSingleStep,
645	Fns&: IgnoreImplicitAsWrittenSingleStep,
646	Fns&: IgnoreElidableImplicitConstructorSingleStep);
647	};
648
649	const Expr *E = cast<ReturnStmt>(Val: St)->getRetValue();
650	const auto *CE = dyn_cast_or_null<CallExpr>(Val: IgnoreParenImplicitAsWritten(E));
651
652	if (!CE) {
653	Diag(St->getBeginLoc(), diag::err_musttail_needs_call) << &MTA;
654	return false;
655	}
656
657	if (const auto *EWC = dyn_cast<ExprWithCleanups>(Val: E)) {
658	if (EWC->cleanupsHaveSideEffects()) {
659	Diag(St->getBeginLoc(), diag::err_musttail_needs_trivial_args) << &MTA;
660	return false;
661	}
662	}
663
664	// We need to determine the full function type (including "this" type, if any)
665	// for both caller and callee.
666	struct FuncType {
667	enum {
668	ft_non_member,
669	ft_static_member,
670	ft_non_static_member,
671	ft_pointer_to_member,
672	} MemberType = ft_non_member;
673
674	QualType This;
675	const FunctionProtoType *Func;
676	const CXXMethodDecl *Method = nullptr;
677	} CallerType, CalleeType;
678
679	auto GetMethodType = [this, St, MTA](const CXXMethodDecl *CMD, FuncType &Type,
680	bool IsCallee) -> bool {
681	if (isa<CXXConstructorDecl, CXXDestructorDecl>(Val: CMD)) {
682	Diag(St->getBeginLoc(), diag::err_musttail_structors_forbidden)
683	<< IsCallee << isa<CXXDestructorDecl>(CMD);
684	if (IsCallee)
685	Diag(CMD->getBeginLoc(), diag::note_musttail_structors_forbidden)
686	<< isa<CXXDestructorDecl>(CMD);
687	Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
688	return false;
689	}
690	if (CMD->isStatic())
691	Type.MemberType = FuncType::ft_static_member;
692	else {
693	Type.This = CMD->getFunctionObjectParameterType();
694	Type.MemberType = FuncType::ft_non_static_member;
695	}
696	Type.Func = CMD->getType()->castAs<FunctionProtoType>();
697	return true;
698	};
699
700	const auto *CallerDecl = dyn_cast<FunctionDecl>(Val: CurContext);
701
702	// Find caller function signature.
703	if (!CallerDecl) {
704	int ContextType;
705	if (isa<BlockDecl>(Val: CurContext))
706	ContextType = 0;
707	else if (isa<ObjCMethodDecl>(Val: CurContext))
708	ContextType = 1;
709	else
710	ContextType = 2;
711	Diag(St->getBeginLoc(), diag::err_musttail_forbidden_from_this_context)
712	<< &MTA << ContextType;
713	return false;
714	} else if (const auto *CMD = dyn_cast<CXXMethodDecl>(Val: CurContext)) {
715	// Caller is a class/struct method.
716	if (!GetMethodType(CMD, CallerType, false))
717	return false;
718	} else {
719	// Caller is a non-method function.
720	CallerType.Func = CallerDecl->getType()->getAs<FunctionProtoType>();
721	}
722
723	const Expr *CalleeExpr = CE->getCallee()->IgnoreParens();
724	const auto *CalleeBinOp = dyn_cast<BinaryOperator>(Val: CalleeExpr);
725	SourceLocation CalleeLoc = CE->getCalleeDecl()
726	? CE->getCalleeDecl()->getBeginLoc()
727	: St->getBeginLoc();
728
729	// Find callee function signature.
730	if (const CXXMethodDecl *CMD =
731	dyn_cast_or_null<CXXMethodDecl>(Val: CE->getCalleeDecl())) {
732	// Call is: obj.method(), obj->method(), functor(), etc.
733	if (!GetMethodType(CMD, CalleeType, true))
734	return false;
735	} else if (CalleeBinOp && CalleeBinOp->isPtrMemOp()) {
736	// Call is: obj->*method_ptr or obj.*method_ptr
737	const auto *MPT =
738	CalleeBinOp->getRHS()->getType()->castAs<MemberPointerType>();
739	CalleeType.This = QualType(MPT->getClass(), 0);
740	CalleeType.Func = MPT->getPointeeType()->castAs<FunctionProtoType>();
741	CalleeType.MemberType = FuncType::ft_pointer_to_member;
742	} else if (isa<CXXPseudoDestructorExpr>(Val: CalleeExpr)) {
743	Diag(St->getBeginLoc(), diag::err_musttail_structors_forbidden)
744	<< /* IsCallee = */ 1 << /* IsDestructor = */ 1;
745	Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
746	return false;
747	} else {
748	// Non-method function.
749	CalleeType.Func =
750	CalleeExpr->getType()->getPointeeType()->getAs<FunctionProtoType>();
751	}
752
753	// Both caller and callee must have a prototype (no K&R declarations).
754	if (!CalleeType.Func || !CallerType.Func) {
755	Diag(St->getBeginLoc(), diag::err_musttail_needs_prototype) << &MTA;
756	if (!CalleeType.Func && CE->getDirectCallee()) {
757	Diag(CE->getDirectCallee()->getBeginLoc(),
758	diag::note_musttail_fix_non_prototype);
759	}
760	if (!CallerType.Func)
761	Diag(CallerDecl->getBeginLoc(), diag::note_musttail_fix_non_prototype);
762	return false;
763	}
764
765	// Caller and callee must have matching calling conventions.
766	//
767	// Some calling conventions are physically capable of supporting tail calls
768	// even if the function types don't perfectly match. LLVM is currently too
769	// strict to allow this, but if LLVM added support for this in the future, we
770	// could exit early here and skip the remaining checks if the functions are
771	// using such a calling convention.
772	if (CallerType.Func->getCallConv() != CalleeType.Func->getCallConv()) {
773	if (const auto *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl()))
774	Diag(St->getBeginLoc(), diag::err_musttail_callconv_mismatch)
775	<< true << ND->getDeclName();
776	else
777	Diag(St->getBeginLoc(), diag::err_musttail_callconv_mismatch) << false;
778	Diag(CalleeLoc, diag::note_musttail_callconv_mismatch)
779	<< FunctionType::getNameForCallConv(CallerType.Func->getCallConv())
780	<< FunctionType::getNameForCallConv(CalleeType.Func->getCallConv());
781	Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
782	return false;
783	}
784
785	if (CalleeType.Func->isVariadic() || CallerType.Func->isVariadic()) {
786	Diag(St->getBeginLoc(), diag::err_musttail_no_variadic) << &MTA;
787	return false;
788	}
789
790	const auto *CalleeDecl = CE->getCalleeDecl();
791	if (CalleeDecl && CalleeDecl->hasAttr<CXX11NoReturnAttr>()) {
792	Diag(St->getBeginLoc(), diag::err_musttail_no_return) << &MTA;
793	return false;
794	}
795
796	// Caller and callee must match in whether they have a "this" parameter.
797	if (CallerType.This.isNull() != CalleeType.This.isNull()) {
798	if (const auto *ND = dyn_cast_or_null<NamedDecl>(Val: CE->getCalleeDecl())) {
799	Diag(St->getBeginLoc(), diag::err_musttail_member_mismatch)
800	<< CallerType.MemberType << CalleeType.MemberType << true
801	<< ND->getDeclName();
802	Diag(CalleeLoc, diag::note_musttail_callee_defined_here)
803	<< ND->getDeclName();
804	} else
805	Diag(St->getBeginLoc(), diag::err_musttail_member_mismatch)
806	<< CallerType.MemberType << CalleeType.MemberType << false;
807	Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
808	return false;
809	}
810
811	auto CheckTypesMatch = [this](FuncType CallerType, FuncType CalleeType,
812	PartialDiagnostic &PD) -> bool {
813	enum {
814	ft_different_class,
815	ft_parameter_arity,
816	ft_parameter_mismatch,
817	ft_return_type,
818	};
819
820	auto DoTypesMatch = [this, &PD](QualType A, QualType B,
821	unsigned Select) -> bool {
822	if (!Context.hasSimilarType(T1: A, T2: B)) {
823	PD << Select << A.getUnqualifiedType() << B.getUnqualifiedType();
824	return false;
825	}
826	return true;
827	};
828
829	if (!CallerType.This.isNull() &&
830	!DoTypesMatch(CallerType.This, CalleeType.This, ft_different_class))
831	return false;
832
833	if (!DoTypesMatch(CallerType.Func->getReturnType(),
834	CalleeType.Func->getReturnType(), ft_return_type))
835	return false;
836
837	if (CallerType.Func->getNumParams() != CalleeType.Func->getNumParams()) {
838	PD << ft_parameter_arity << CallerType.Func->getNumParams()
839	<< CalleeType.Func->getNumParams();
840	return false;
841	}
842
843	ArrayRef<QualType> CalleeParams = CalleeType.Func->getParamTypes();
844	ArrayRef<QualType> CallerParams = CallerType.Func->getParamTypes();
845	size_t N = CallerType.Func->getNumParams();
846	for (size_t I = 0; I < N; I++) {
847	if (!DoTypesMatch(CalleeParams[I], CallerParams[I],
848	ft_parameter_mismatch)) {
849	PD << static_cast<int>(I) + 1;
850	return false;
851	}
852	}
853
854	return true;
855	};
856
857	PartialDiagnostic PD = PDiag(diag::note_musttail_mismatch);
858	if (!CheckTypesMatch(CallerType, CalleeType, PD)) {
859	if (const auto *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl()))
860	Diag(St->getBeginLoc(), diag::err_musttail_mismatch)
861	<< true << ND->getDeclName();
862	else
863	Diag(St->getBeginLoc(), diag::err_musttail_mismatch) << false;
864	Diag(Loc: CalleeLoc, PD);
865	Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
866	return false;
867	}
868
869	return true;
870	}
871
872	namespace {
873	class CommaVisitor : public EvaluatedExprVisitor<CommaVisitor> {
874	typedef EvaluatedExprVisitor<CommaVisitor> Inherited;
875	Sema &SemaRef;
876	public:
877	CommaVisitor(Sema &SemaRef) : Inherited(SemaRef.Context), SemaRef(SemaRef) {}
878	void VisitBinaryOperator(BinaryOperator *E) {
879	if (E->getOpcode() == BO_Comma)
880	SemaRef.DiagnoseCommaOperator(LHS: E->getLHS(), Loc: E->getExprLoc());
881	EvaluatedExprVisitor<CommaVisitor>::VisitBinaryOperator(E);
882	}
883	};
884	}
885
886	StmtResult Sema::ActOnIfStmt(SourceLocation IfLoc,
887	IfStatementKind StatementKind,
888	SourceLocation LParenLoc, Stmt *InitStmt,
889	ConditionResult Cond, SourceLocation RParenLoc,
890	Stmt *thenStmt, SourceLocation ElseLoc,
891	Stmt *elseStmt) {
892	if (Cond.isInvalid())
893	return StmtError();
894
895	bool ConstevalOrNegatedConsteval =
896	StatementKind == IfStatementKind::ConstevalNonNegated ||
897	StatementKind == IfStatementKind::ConstevalNegated;
898
899	Expr *CondExpr = Cond.get().second;
900	assert((CondExpr || ConstevalOrNegatedConsteval) &&
901	"If statement: missing condition");
902	// Only call the CommaVisitor when not C89 due to differences in scope flags.
903	if (CondExpr && (getLangOpts().C99 || getLangOpts().CPlusPlus) &&
904	!Diags.isIgnored(diag::warn_comma_operator, CondExpr->getExprLoc()))
905	CommaVisitor(*this).Visit(CondExpr);
906
907	if (!ConstevalOrNegatedConsteval && !elseStmt)
908	DiagnoseEmptyStmtBody(RParenLoc, thenStmt, diag::warn_empty_if_body);
909
910	if (ConstevalOrNegatedConsteval ||
911	StatementKind == IfStatementKind::Constexpr) {
912	auto DiagnoseLikelihood = [&](const Stmt *S) {
913	if (const Attr *A = Stmt::getLikelihoodAttr(S)) {
914	Diags.Report(A->getLocation(),
915	diag::warn_attribute_has_no_effect_on_compile_time_if)
916	<< A << ConstevalOrNegatedConsteval << A->getRange();
917	Diags.Report(IfLoc,
918	diag::note_attribute_has_no_effect_on_compile_time_if_here)
919	<< ConstevalOrNegatedConsteval
920	<< SourceRange(IfLoc, (ConstevalOrNegatedConsteval
921	? thenStmt->getBeginLoc()
922	: LParenLoc)
923	.getLocWithOffset(-1));
924	}
925	};
926	DiagnoseLikelihood(thenStmt);
927	DiagnoseLikelihood(elseStmt);
928	} else {
929	std::tuple<bool, const Attr *, const Attr *> LHC =
930	Stmt::determineLikelihoodConflict(Then: thenStmt, Else: elseStmt);
931	if (std::get<0>(t&: LHC)) {
932	const Attr *ThenAttr = std::get<1>(t&: LHC);
933	const Attr *ElseAttr = std::get<2>(t&: LHC);
934	Diags.Report(ThenAttr->getLocation(),
935	diag::warn_attributes_likelihood_ifstmt_conflict)
936	<< ThenAttr << ThenAttr->getRange();
937	Diags.Report(ElseAttr->getLocation(), diag::note_conflicting_attribute)
938	<< ElseAttr << ElseAttr->getRange();
939	}
940	}
941
942	if (ConstevalOrNegatedConsteval) {
943	bool Immediate = ExprEvalContexts.back().Context ==
944	ExpressionEvaluationContext::ImmediateFunctionContext;
945	if (CurContext->isFunctionOrMethod()) {
946	const auto *FD =
947	dyn_cast<FunctionDecl>(Val: Decl::castFromDeclContext(CurContext));
948	if (FD && FD->isImmediateFunction())
949	Immediate = true;
950	}
951	if (isUnevaluatedContext() || Immediate)
952	Diags.Report(IfLoc, diag::warn_consteval_if_always_true) << Immediate;
953	}
954
955	return BuildIfStmt(IfLoc, StatementKind, LParenLoc, InitStmt, Cond, RParenLoc,
956	ThenVal: thenStmt, ElseLoc, ElseVal: elseStmt);
957	}
958
959	StmtResult Sema::BuildIfStmt(SourceLocation IfLoc,
960	IfStatementKind StatementKind,
961	SourceLocation LParenLoc, Stmt *InitStmt,
962	ConditionResult Cond, SourceLocation RParenLoc,
963	Stmt *thenStmt, SourceLocation ElseLoc,
964	Stmt *elseStmt) {
965	if (Cond.isInvalid())
966	return StmtError();
967
968	if (StatementKind != IfStatementKind::Ordinary ||
969	isa<ObjCAvailabilityCheckExpr>(Val: Cond.get().second))
970	setFunctionHasBranchProtectedScope();
971
972	return IfStmt::Create(Ctx: Context, IL: IfLoc, Kind: StatementKind, Init: InitStmt,
973	Var: Cond.get().first, Cond: Cond.get().second, LPL: LParenLoc,
974	RPL: RParenLoc, Then: thenStmt, EL: ElseLoc, Else: elseStmt);
975	}
976
977	namespace {
978	struct CaseCompareFunctor {
979	bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
980	const llvm::APSInt &RHS) {
981	return LHS.first < RHS;
982	}
983	bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
984	const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
985	return LHS.first < RHS.first;
986	}
987	bool operator()(const llvm::APSInt &LHS,
988	const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
989	return LHS < RHS.first;
990	}
991	};
992	}
993
994	/// CmpCaseVals - Comparison predicate for sorting case values.
995	///
996	static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
997	const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
998	if (lhs.first < rhs.first)
999	return true;
1000
1001	if (lhs.first == rhs.first &&
1002	lhs.second->getCaseLoc() < rhs.second->getCaseLoc())
1003	return true;
1004	return false;
1005	}
1006
1007	/// CmpEnumVals - Comparison predicate for sorting enumeration values.
1008	///
1009	static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
1010	const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
1011	{
1012	return lhs.first < rhs.first;
1013	}
1014
1015	/// EqEnumVals - Comparison preficate for uniqing enumeration values.
1016	///
1017	static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
1018	const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
1019	{
1020	return lhs.first == rhs.first;
1021	}
1022
1023	/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
1024	/// potentially integral-promoted expression @p expr.
1025	static QualType GetTypeBeforeIntegralPromotion(const Expr *&E) {
1026	if (const auto *FE = dyn_cast<FullExpr>(Val: E))
1027	E = FE->getSubExpr();
1028	while (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(Val: E)) {
1029	if (ImpCast->getCastKind() != CK_IntegralCast) break;
1030	E = ImpCast->getSubExpr();
1031	}
1032	return E->getType();
1033	}
1034
1035	ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) {
1036	class SwitchConvertDiagnoser : public ICEConvertDiagnoser {
1037	Expr *Cond;
1038
1039	public:
1040	SwitchConvertDiagnoser(Expr *Cond)
1041	: ICEConvertDiagnoser(/*AllowScopedEnumerations*/true, false, true),
1042	Cond(Cond) {}
1043
1044	SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
1045	QualType T) override {
1046	return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T;
1047	}
1048
1049	SemaDiagnosticBuilder diagnoseIncomplete(
1050	Sema &S, SourceLocation Loc, QualType T) override {
1051	return S.Diag(Loc, diag::err_switch_incomplete_class_type)
1052	<< T << Cond->getSourceRange();
1053	}
1054
1055	SemaDiagnosticBuilder diagnoseExplicitConv(
1056	Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
1057	return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy;
1058	}
1059
1060	SemaDiagnosticBuilder noteExplicitConv(
1061	Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
1062	return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
1063	<< ConvTy->isEnumeralType() << ConvTy;
1064	}
1065
1066	SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
1067	QualType T) override {
1068	return S.Diag(Loc, diag::err_switch_multiple_conversions) << T;
1069	}
1070
1071	SemaDiagnosticBuilder noteAmbiguous(
1072	Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
1073	return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
1074	<< ConvTy->isEnumeralType() << ConvTy;
1075	}
1076
1077	SemaDiagnosticBuilder diagnoseConversion(
1078	Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
1079	llvm_unreachable("conversion functions are permitted");
1080	}
1081	} SwitchDiagnoser(Cond);
1082
1083	ExprResult CondResult =
1084	PerformContextualImplicitConversion(Loc: SwitchLoc, FromE: Cond, Converter&: SwitchDiagnoser);
1085	if (CondResult.isInvalid())
1086	return ExprError();
1087
1088	// FIXME: PerformContextualImplicitConversion doesn't always tell us if it
1089	// failed and produced a diagnostic.
1090	Cond = CondResult.get();
1091	if (!Cond->isTypeDependent() &&
1092	!Cond->getType()->isIntegralOrEnumerationType())
1093	return ExprError();
1094
1095	// C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
1096	return UsualUnaryConversions(E: Cond);
1097	}
1098
1099	StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
1100	SourceLocation LParenLoc,
1101	Stmt *InitStmt, ConditionResult Cond,
1102	SourceLocation RParenLoc) {
1103	Expr *CondExpr = Cond.get().second;
1104	assert((Cond.isInvalid() || CondExpr) && "switch with no condition");
1105
1106	if (CondExpr && !CondExpr->isTypeDependent()) {
1107	// We have already converted the expression to an integral or enumeration
1108	// type, when we parsed the switch condition. There are cases where we don't
1109	// have an appropriate type, e.g. a typo-expr Cond was corrected to an
1110	// inappropriate-type expr, we just return an error.
1111	if (!CondExpr->getType()->isIntegralOrEnumerationType())
1112	return StmtError();
1113	if (CondExpr->isKnownToHaveBooleanValue()) {
1114	// switch(bool_expr) {...} is often a programmer error, e.g.
1115	// switch(n && mask) { ... } // Doh - should be "n & mask".
1116	// One can always use an if statement instead of switch(bool_expr).
1117	Diag(SwitchLoc, diag::warn_bool_switch_condition)
1118	<< CondExpr->getSourceRange();
1119	}
1120	}
1121
1122	setFunctionHasBranchIntoScope();
1123
1124	auto *SS = SwitchStmt::Create(Ctx: Context, Init: InitStmt, Var: Cond.get().first, Cond: CondExpr,
1125	LParenLoc, RParenLoc);
1126	getCurFunction()->SwitchStack.push_back(
1127	Elt: FunctionScopeInfo::SwitchInfo(SS, false));
1128	return SS;
1129	}
1130
1131	static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
1132	Val = Val.extOrTrunc(width: BitWidth);
1133	Val.setIsSigned(IsSigned);
1134	}
1135
1136	/// Check the specified case value is in range for the given unpromoted switch
1137	/// type.
1138	static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val,
1139	unsigned UnpromotedWidth, bool UnpromotedSign) {
1140	// In C++11 onwards, this is checked by the language rules.
1141	if (S.getLangOpts().CPlusPlus11)
1142	return;
1143
1144	// If the case value was signed and negative and the switch expression is
1145	// unsigned, don't bother to warn: this is implementation-defined behavior.
1146	// FIXME: Introduce a second, default-ignored warning for this case?
1147	if (UnpromotedWidth < Val.getBitWidth()) {
1148	llvm::APSInt ConvVal(Val);
1149	AdjustAPSInt(Val&: ConvVal, BitWidth: UnpromotedWidth, IsSigned: UnpromotedSign);
1150	AdjustAPSInt(Val&: ConvVal, BitWidth: Val.getBitWidth(), IsSigned: Val.isSigned());
1151	// FIXME: Use different diagnostics for overflow in conversion to promoted
1152	// type versus "switch expression cannot have this value". Use proper
1153	// IntRange checking rather than just looking at the unpromoted type here.
1154	if (ConvVal != Val)
1155	S.Diag(Loc, diag::warn_case_value_overflow) << toString(Val, 10)
1156	<< toString(ConvVal, 10);
1157	}
1158	}
1159
1160	typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
1161
1162	/// Returns true if we should emit a diagnostic about this case expression not
1163	/// being a part of the enum used in the switch controlling expression.
1164	static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
1165	const EnumDecl *ED,
1166	const Expr *CaseExpr,
1167	EnumValsTy::iterator &EI,
1168	EnumValsTy::iterator &EIEnd,
1169	const llvm::APSInt &Val) {
1170	if (!ED->isClosed())
1171	return false;
1172
1173	if (const DeclRefExpr *DRE =
1174	dyn_cast<DeclRefExpr>(Val: CaseExpr->IgnoreParenImpCasts())) {
1175	if (const VarDecl *VD = dyn_cast<VarDecl>(Val: DRE->getDecl())) {
1176	QualType VarType = VD->getType();
1177	QualType EnumType = S.Context.getTypeDeclType(ED);
1178	if (VD->hasGlobalStorage() && VarType.isConstQualified() &&
1179	S.Context.hasSameUnqualifiedType(T1: EnumType, T2: VarType))
1180	return false;
1181	}
1182	}
1183
1184	if (ED->hasAttr<FlagEnumAttr>())
1185	return !S.IsValueInFlagEnum(ED, Val, AllowMask: false);
1186
1187	while (EI != EIEnd && EI->first < Val)
1188	EI++;
1189
1190	if (EI != EIEnd && EI->first == Val)
1191	return false;
1192
1193	return true;
1194	}
1195
1196	static void checkEnumTypesInSwitchStmt(Sema &S, const Expr *Cond,
1197	const Expr *Case) {
1198	QualType CondType = Cond->getType();
1199	QualType CaseType = Case->getType();
1200
1201	const EnumType *CondEnumType = CondType->getAs<EnumType>();
1202	const EnumType *CaseEnumType = CaseType->getAs<EnumType>();
1203	if (!CondEnumType || !CaseEnumType)
1204	return;
1205
1206	// Ignore anonymous enums.
1207	if (!CondEnumType->getDecl()->getIdentifier() &&
1208	!CondEnumType->getDecl()->getTypedefNameForAnonDecl())
1209	return;
1210	if (!CaseEnumType->getDecl()->getIdentifier() &&
1211	!CaseEnumType->getDecl()->getTypedefNameForAnonDecl())
1212	return;
1213
1214	if (S.Context.hasSameUnqualifiedType(T1: CondType, T2: CaseType))
1215	return;
1216
1217	S.Diag(Case->getExprLoc(), diag::warn_comparison_of_mixed_enum_types_switch)
1218	<< CondType << CaseType << Cond->getSourceRange()
1219	<< Case->getSourceRange();
1220	}
1221
1222	StmtResult
1223	Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
1224	Stmt *BodyStmt) {
1225	SwitchStmt *SS = cast<SwitchStmt>(Val: Switch);
1226	bool CaseListIsIncomplete = getCurFunction()->SwitchStack.back().getInt();
1227	assert(SS == getCurFunction()->SwitchStack.back().getPointer() &&
1228	"switch stack missing push/pop!");
1229
1230	getCurFunction()->SwitchStack.pop_back();
1231
1232	if (!BodyStmt) return StmtError();
1233	SS->setBody(S: BodyStmt, SL: SwitchLoc);
1234
1235	Expr *CondExpr = SS->getCond();
1236	if (!CondExpr) return StmtError();
1237
1238	QualType CondType = CondExpr->getType();
1239
1240	// C++ 6.4.2.p2:
1241	// Integral promotions are performed (on the switch condition).
1242	//
1243	// A case value unrepresentable by the original switch condition
1244	// type (before the promotion) doesn't make sense, even when it can
1245	// be represented by the promoted type. Therefore we need to find
1246	// the pre-promotion type of the switch condition.
1247	const Expr *CondExprBeforePromotion = CondExpr;
1248	QualType CondTypeBeforePromotion =
1249	GetTypeBeforeIntegralPromotion(E&: CondExprBeforePromotion);
1250
1251	// Get the bitwidth of the switched-on value after promotions. We must
1252	// convert the integer case values to this width before comparison.
1253	bool HasDependentValue
1254	= CondExpr->isTypeDependent() || CondExpr->isValueDependent();
1255	unsigned CondWidth = HasDependentValue ? 0 : Context.getIntWidth(T: CondType);
1256	bool CondIsSigned = CondType->isSignedIntegerOrEnumerationType();
1257
1258	// Get the width and signedness that the condition might actually have, for
1259	// warning purposes.
1260	// FIXME: Grab an IntRange for the condition rather than using the unpromoted
1261	// type.
1262	unsigned CondWidthBeforePromotion
1263	= HasDependentValue ? 0 : Context.getIntWidth(T: CondTypeBeforePromotion);
1264	bool CondIsSignedBeforePromotion
1265	= CondTypeBeforePromotion->isSignedIntegerOrEnumerationType();
1266
1267	// Accumulate all of the case values in a vector so that we can sort them
1268	// and detect duplicates. This vector contains the APInt for the case after
1269	// it has been converted to the condition type.
1270	typedef SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
1271	CaseValsTy CaseVals;
1272
1273	// Keep track of any GNU case ranges we see. The APSInt is the low value.
1274	typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
1275	CaseRangesTy CaseRanges;
1276
1277	DefaultStmt *TheDefaultStmt = nullptr;
1278
1279	bool CaseListIsErroneous = false;
1280
1281	// FIXME: We'd better diagnose missing or duplicate default labels even
1282	// in the dependent case. Because default labels themselves are never
1283	// dependent.
1284	for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
1285	SC = SC->getNextSwitchCase()) {
1286
1287	if (DefaultStmt *DS = dyn_cast<DefaultStmt>(Val: SC)) {
1288	if (TheDefaultStmt) {
1289	Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
1290	Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
1291
1292	// FIXME: Remove the default statement from the switch block so that
1293	// we'll return a valid AST. This requires recursing down the AST and
1294	// finding it, not something we are set up to do right now. For now,
1295	// just lop the entire switch stmt out of the AST.
1296	CaseListIsErroneous = true;
1297	}
1298	TheDefaultStmt = DS;
1299
1300	} else {
1301	CaseStmt *CS = cast<CaseStmt>(Val: SC);
1302
1303	Expr *Lo = CS->getLHS();
1304
1305	if (Lo->isValueDependent()) {
1306	HasDependentValue = true;
1307	break;
1308	}
1309
1310	// We already verified that the expression has a constant value;
1311	// get that value (prior to conversions).
1312	const Expr *LoBeforePromotion = Lo;
1313	GetTypeBeforeIntegralPromotion(E&: LoBeforePromotion);
1314	llvm::APSInt LoVal = LoBeforePromotion->EvaluateKnownConstInt(Ctx: Context);
1315
1316	// Check the unconverted value is within the range of possible values of
1317	// the switch expression.
1318	checkCaseValue(*this, Lo->getBeginLoc(), LoVal, CondWidthBeforePromotion,
1319	CondIsSignedBeforePromotion);
1320
1321	// FIXME: This duplicates the check performed for warn_not_in_enum below.
1322	checkEnumTypesInSwitchStmt(S&: *this, Cond: CondExprBeforePromotion,
1323	Case: LoBeforePromotion);
1324
1325	// Convert the value to the same width/sign as the condition.
1326	AdjustAPSInt(Val&: LoVal, BitWidth: CondWidth, IsSigned: CondIsSigned);
1327
1328	// If this is a case range, remember it in CaseRanges, otherwise CaseVals.
1329	if (CS->getRHS()) {
1330	if (CS->getRHS()->isValueDependent()) {
1331	HasDependentValue = true;
1332	break;
1333	}
1334	CaseRanges.push_back(x: std::make_pair(x&: LoVal, y&: CS));
1335	} else
1336	CaseVals.push_back(Elt: std::make_pair(x&: LoVal, y&: CS));
1337	}
1338	}
1339
1340	if (!HasDependentValue) {
1341	// If we don't have a default statement, check whether the
1342	// condition is constant.
1343	llvm::APSInt ConstantCondValue;
1344	bool HasConstantCond = false;
1345	if (!TheDefaultStmt) {
1346	Expr::EvalResult Result;
1347	HasConstantCond = CondExpr->EvaluateAsInt(Result, Ctx: Context,
1348	AllowSideEffects: Expr::SE_AllowSideEffects);
1349	if (Result.Val.isInt())
1350	ConstantCondValue = Result.Val.getInt();
1351	assert(!HasConstantCond ||
1352	(ConstantCondValue.getBitWidth() == CondWidth &&
1353	ConstantCondValue.isSigned() == CondIsSigned));
1354	Diag(SwitchLoc, diag::warn_switch_default);
1355	}
1356	bool ShouldCheckConstantCond = HasConstantCond;
1357
1358	// Sort all the scalar case values so we can easily detect duplicates.
1359	llvm::stable_sort(Range&: CaseVals, C: CmpCaseVals);
1360
1361	if (!CaseVals.empty()) {
1362	for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
1363	if (ShouldCheckConstantCond &&
1364	CaseVals[i].first == ConstantCondValue)
1365	ShouldCheckConstantCond = false;
1366
1367	if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
1368	// If we have a duplicate, report it.
1369	// First, determine if either case value has a name
1370	StringRef PrevString, CurrString;
1371	Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts();
1372	Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts();
1373	if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(Val: PrevCase)) {
1374	PrevString = DeclRef->getDecl()->getName();
1375	}
1376	if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(Val: CurrCase)) {
1377	CurrString = DeclRef->getDecl()->getName();
1378	}
1379	SmallString<16> CaseValStr;
1380	CaseVals[i-1].first.toString(Str&: CaseValStr);
1381
1382	if (PrevString == CurrString)
1383	Diag(CaseVals[i].second->getLHS()->getBeginLoc(),
1384	diag::err_duplicate_case)
1385	<< (PrevString.empty() ? CaseValStr.str() : PrevString);
1386	else
1387	Diag(CaseVals[i].second->getLHS()->getBeginLoc(),
1388	diag::err_duplicate_case_differing_expr)
1389	<< (PrevString.empty() ? CaseValStr.str() : PrevString)
1390	<< (CurrString.empty() ? CaseValStr.str() : CurrString)
1391	<< CaseValStr;
1392
1393	Diag(CaseVals[i - 1].second->getLHS()->getBeginLoc(),
1394	diag::note_duplicate_case_prev);
1395	// FIXME: We really want to remove the bogus case stmt from the
1396	// substmt, but we have no way to do this right now.
1397	CaseListIsErroneous = true;
1398	}
1399	}
1400	}
1401
1402	// Detect duplicate case ranges, which usually don't exist at all in
1403	// the first place.
1404	if (!CaseRanges.empty()) {
1405	// Sort all the case ranges by their low value so we can easily detect
1406	// overlaps between ranges.
1407	llvm::stable_sort(Range&: CaseRanges);
1408
1409	// Scan the ranges, computing the high values and removing empty ranges.
1410	std::vector<llvm::APSInt> HiVals;
1411	for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1412	llvm::APSInt &LoVal = CaseRanges[i].first;
1413	CaseStmt *CR = CaseRanges[i].second;
1414	Expr *Hi = CR->getRHS();
1415
1416	const Expr *HiBeforePromotion = Hi;
1417	GetTypeBeforeIntegralPromotion(E&: HiBeforePromotion);
1418	llvm::APSInt HiVal = HiBeforePromotion->EvaluateKnownConstInt(Ctx: Context);
1419
1420	// Check the unconverted value is within the range of possible values of
1421	// the switch expression.
1422	checkCaseValue(*this, Hi->getBeginLoc(), HiVal,
1423	CondWidthBeforePromotion, CondIsSignedBeforePromotion);
1424
1425	// Convert the value to the same width/sign as the condition.
1426	AdjustAPSInt(Val&: HiVal, BitWidth: CondWidth, IsSigned: CondIsSigned);
1427
1428	// If the low value is bigger than the high value, the case is empty.
1429	if (LoVal > HiVal) {
1430	Diag(CR->getLHS()->getBeginLoc(), diag::warn_case_empty_range)
1431	<< SourceRange(CR->getLHS()->getBeginLoc(), Hi->getEndLoc());
1432	CaseRanges.erase(position: CaseRanges.begin()+i);
1433	--i;
1434	--e;
1435	continue;
1436	}
1437
1438	if (ShouldCheckConstantCond &&
1439	LoVal <= ConstantCondValue &&
1440	ConstantCondValue <= HiVal)
1441	ShouldCheckConstantCond = false;
1442
1443	HiVals.push_back(x: HiVal);
1444	}
1445
1446	// Rescan the ranges, looking for overlap with singleton values and other
1447	// ranges. Since the range list is sorted, we only need to compare case
1448	// ranges with their neighbors.
1449	for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1450	llvm::APSInt &CRLo = CaseRanges[i].first;
1451	llvm::APSInt &CRHi = HiVals[i];
1452	CaseStmt *CR = CaseRanges[i].second;
1453
1454	// Check to see whether the case range overlaps with any
1455	// singleton cases.
1456	CaseStmt *OverlapStmt = nullptr;
1457	llvm::APSInt OverlapVal(32);
1458
1459	// Find the smallest value >= the lower bound. If I is in the
1460	// case range, then we have overlap.
1461	CaseValsTy::iterator I =
1462	llvm::lower_bound(Range&: CaseVals, Value&: CRLo, C: CaseCompareFunctor());
1463	if (I != CaseVals.end() && I->first < CRHi) {
1464	OverlapVal = I->first; // Found overlap with scalar.
1465	OverlapStmt = I->second;
1466	}
1467
1468	// Find the smallest value bigger than the upper bound.
1469	I = std::upper_bound(first: I, last: CaseVals.end(), val: CRHi, comp: CaseCompareFunctor());
1470	if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
1471	OverlapVal = (I-1)->first; // Found overlap with scalar.
1472	OverlapStmt = (I-1)->second;
1473	}
1474
1475	// Check to see if this case stmt overlaps with the subsequent
1476	// case range.
1477	if (i && CRLo <= HiVals[i-1]) {
1478	OverlapVal = HiVals[i-1]; // Found overlap with range.
1479	OverlapStmt = CaseRanges[i-1].second;
1480	}
1481
1482	if (OverlapStmt) {
1483	// If we have a duplicate, report it.
1484	Diag(CR->getLHS()->getBeginLoc(), diag::err_duplicate_case)
1485	<< toString(OverlapVal, 10);
1486	Diag(OverlapStmt->getLHS()->getBeginLoc(),
1487	diag::note_duplicate_case_prev);
1488	// FIXME: We really want to remove the bogus case stmt from the
1489	// substmt, but we have no way to do this right now.
1490	CaseListIsErroneous = true;
1491	}
1492	}
1493	}
1494
1495	// Complain if we have a constant condition and we didn't find a match.
1496	if (!CaseListIsErroneous && !CaseListIsIncomplete &&
1497	ShouldCheckConstantCond) {
1498	// TODO: it would be nice if we printed enums as enums, chars as
1499	// chars, etc.
1500	Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
1501	<< toString(ConstantCondValue, 10)
1502	<< CondExpr->getSourceRange();
1503	}
1504
1505	// Check to see if switch is over an Enum and handles all of its
1506	// values. We only issue a warning if there is not 'default:', but
1507	// we still do the analysis to preserve this information in the AST
1508	// (which can be used by flow-based analyes).
1509	//
1510	const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
1511
1512	// If switch has default case, then ignore it.
1513	if (!CaseListIsErroneous && !CaseListIsIncomplete && !HasConstantCond &&
1514	ET && ET->getDecl()->isCompleteDefinition() &&
1515	!ET->getDecl()->enumerators().empty()) {
1516	const EnumDecl *ED = ET->getDecl();
1517	EnumValsTy EnumVals;
1518
1519	// Gather all enum values, set their type and sort them,
1520	// allowing easier comparison with CaseVals.
1521	for (auto *EDI : ED->enumerators()) {
1522	llvm::APSInt Val = EDI->getInitVal();
1523	AdjustAPSInt(Val, BitWidth: CondWidth, IsSigned: CondIsSigned);
1524	EnumVals.push_back(Elt: std::make_pair(x&: Val, y&: EDI));
1525	}
1526	llvm::stable_sort(Range&: EnumVals, C: CmpEnumVals);
1527	auto EI = EnumVals.begin(), EIEnd =
1528	std::unique(first: EnumVals.begin(), last: EnumVals.end(), binary_pred: EqEnumVals);
1529
1530	// See which case values aren't in enum.
1531	for (CaseValsTy::const_iterator CI = CaseVals.begin();
1532	CI != CaseVals.end(); CI++) {
1533	Expr *CaseExpr = CI->second->getLHS();
1534	if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1535	CI->first))
1536	Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1537	<< CondTypeBeforePromotion;
1538	}
1539
1540	// See which of case ranges aren't in enum
1541	EI = EnumVals.begin();
1542	for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
1543	RI != CaseRanges.end(); RI++) {
1544	Expr *CaseExpr = RI->second->getLHS();
1545	if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1546	RI->first))
1547	Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1548	<< CondTypeBeforePromotion;
1549
1550	llvm::APSInt Hi =
1551	RI->second->getRHS()->EvaluateKnownConstInt(Ctx: Context);
1552	AdjustAPSInt(Val&: Hi, BitWidth: CondWidth, IsSigned: CondIsSigned);
1553
1554	CaseExpr = RI->second->getRHS();
1555	if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1556	Hi))
1557	Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1558	<< CondTypeBeforePromotion;
1559	}
1560
1561	// Check which enum vals aren't in switch
1562	auto CI = CaseVals.begin();
1563	auto RI = CaseRanges.begin();
1564	bool hasCasesNotInSwitch = false;
1565
1566	SmallVector<DeclarationName,8> UnhandledNames;
1567
1568	for (EI = EnumVals.begin(); EI != EIEnd; EI++) {
1569	// Don't warn about omitted unavailable EnumConstantDecls.
1570	switch (EI->second->getAvailability()) {
1571	case AR_Deprecated:
1572	// Omitting a deprecated constant is ok; it should never materialize.
1573	case AR_Unavailable:
1574	continue;
1575
1576	case AR_NotYetIntroduced:
1577	// Partially available enum constants should be present. Note that we
1578	// suppress -Wunguarded-availability diagnostics for such uses.
1579	case AR_Available:
1580	break;
1581	}
1582
1583	if (EI->second->hasAttr<UnusedAttr>())
1584	continue;
1585
1586	// Drop unneeded case values
1587	while (CI != CaseVals.end() && CI->first < EI->first)
1588	CI++;
1589
1590	if (CI != CaseVals.end() && CI->first == EI->first)
1591	continue;
1592
1593	// Drop unneeded case ranges
1594	for (; RI != CaseRanges.end(); RI++) {
1595	llvm::APSInt Hi =
1596	RI->second->getRHS()->EvaluateKnownConstInt(Ctx: Context);
1597	AdjustAPSInt(Val&: Hi, BitWidth: CondWidth, IsSigned: CondIsSigned);
1598	if (EI->first <= Hi)
1599	break;
1600	}
1601
1602	if (RI == CaseRanges.end() || EI->first < RI->first) {
1603	hasCasesNotInSwitch = true;
1604	UnhandledNames.push_back(Elt: EI->second->getDeclName());
1605	}
1606	}
1607
1608	if (TheDefaultStmt && UnhandledNames.empty() && ED->isClosedNonFlag())
1609	Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
1610
1611	// Produce a nice diagnostic if multiple values aren't handled.
1612	if (!UnhandledNames.empty()) {
1613	auto DB = Diag(CondExpr->getExprLoc(), TheDefaultStmt
1614	? diag::warn_def_missing_case
1615	: diag::warn_missing_case)
1616	<< CondExpr->getSourceRange() << (int)UnhandledNames.size();
1617
1618	for (size_t I = 0, E = std::min(a: UnhandledNames.size(), b: (size_t)3);
1619	I != E; ++I)
1620	DB << UnhandledNames[I];
1621	}
1622
1623	if (!hasCasesNotInSwitch)
1624	SS->setAllEnumCasesCovered();
1625	}
1626	}
1627
1628	if (BodyStmt)
1629	DiagnoseEmptyStmtBody(CondExpr->getEndLoc(), BodyStmt,
1630	diag::warn_empty_switch_body);
1631
1632	// FIXME: If the case list was broken is some way, we don't have a good system
1633	// to patch it up. Instead, just return the whole substmt as broken.
1634	if (CaseListIsErroneous)
1635	return StmtError();
1636
1637	return SS;
1638	}
1639
1640	void
1641	Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
1642	Expr *SrcExpr) {
1643	if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc()))
1644	return;
1645
1646	if (const EnumType *ET = DstType->getAs<EnumType>())
1647	if (!Context.hasSameUnqualifiedType(T1: SrcType, T2: DstType) &&
1648	SrcType->isIntegerType()) {
1649	if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
1650	SrcExpr->isIntegerConstantExpr(Ctx: Context)) {
1651	// Get the bitwidth of the enum value before promotions.
1652	unsigned DstWidth = Context.getIntWidth(T: DstType);
1653	bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
1654
1655	llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Ctx: Context);
1656	AdjustAPSInt(Val&: RhsVal, BitWidth: DstWidth, IsSigned: DstIsSigned);
1657	const EnumDecl *ED = ET->getDecl();
1658
1659	if (!ED->isClosed())
1660	return;
1661
1662	if (ED->hasAttr<FlagEnumAttr>()) {
1663	if (!IsValueInFlagEnum(ED, RhsVal, true))
1664	Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1665	<< DstType.getUnqualifiedType();
1666	} else {
1667	typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl *>, 64>
1668	EnumValsTy;
1669	EnumValsTy EnumVals;
1670
1671	// Gather all enum values, set their type and sort them,
1672	// allowing easier comparison with rhs constant.
1673	for (auto *EDI : ED->enumerators()) {
1674	llvm::APSInt Val = EDI->getInitVal();
1675	AdjustAPSInt(Val, BitWidth: DstWidth, IsSigned: DstIsSigned);
1676	EnumVals.push_back(Elt: std::make_pair(x&: Val, y&: EDI));
1677	}
1678	if (EnumVals.empty())
1679	return;
1680	llvm::stable_sort(Range&: EnumVals, C: CmpEnumVals);
1681	EnumValsTy::iterator EIend =
1682	std::unique(first: EnumVals.begin(), last: EnumVals.end(), binary_pred: EqEnumVals);
1683
1684	// See which values aren't in the enum.
1685	EnumValsTy::const_iterator EI = EnumVals.begin();
1686	while (EI != EIend && EI->first < RhsVal)
1687	EI++;
1688	if (EI == EIend || EI->first != RhsVal) {
1689	Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1690	<< DstType.getUnqualifiedType();
1691	}
1692	}
1693	}
1694	}
1695	}
1696
1697	StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc,
1698	SourceLocation LParenLoc, ConditionResult Cond,
1699	SourceLocation RParenLoc, Stmt *Body) {
1700	if (Cond.isInvalid())
1701	return StmtError();
1702
1703	auto CondVal = Cond.get();
1704	CheckBreakContinueBinding(E: CondVal.second);
1705
1706	if (CondVal.second &&
1707	!Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc()))
1708	CommaVisitor(*this).Visit(CondVal.second);
1709
1710	if (isa<NullStmt>(Val: Body))
1711	getCurCompoundScope().setHasEmptyLoopBodies();
1712
1713	return WhileStmt::Create(Ctx: Context, Var: CondVal.first, Cond: CondVal.second, Body,
1714	WL: WhileLoc, LParenLoc, RParenLoc);
1715	}
1716
1717	StmtResult
1718	Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
1719	SourceLocation WhileLoc, SourceLocation CondLParen,
1720	Expr *Cond, SourceLocation CondRParen) {
1721	assert(Cond && "ActOnDoStmt(): missing expression");
1722
1723	CheckBreakContinueBinding(E: Cond);
1724	ExprResult CondResult = CheckBooleanCondition(Loc: DoLoc, E: Cond);
1725	if (CondResult.isInvalid())
1726	return StmtError();
1727	Cond = CondResult.get();
1728
1729	CondResult = ActOnFinishFullExpr(Expr: Cond, CC: DoLoc, /*DiscardedValue*/ false);
1730	if (CondResult.isInvalid())
1731	return StmtError();
1732	Cond = CondResult.get();
1733
1734	// Only call the CommaVisitor for C89 due to differences in scope flags.
1735	if (Cond && !getLangOpts().C99 && !getLangOpts().CPlusPlus &&
1736	!Diags.isIgnored(diag::warn_comma_operator, Cond->getExprLoc()))
1737	CommaVisitor(*this).Visit(Cond);
1738
1739	return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen);
1740	}
1741
1742	namespace {
1743	// Use SetVector since the diagnostic cares about the ordering of the Decl's.
1744	using DeclSetVector = llvm::SmallSetVector<VarDecl *, 8>;
1745
1746	// This visitor will traverse a conditional statement and store all
1747	// the evaluated decls into a vector. Simple is set to true if none
1748	// of the excluded constructs are used.
1749	class DeclExtractor : public EvaluatedExprVisitor<DeclExtractor> {
1750	DeclSetVector &Decls;
1751	SmallVectorImpl<SourceRange> &Ranges;
1752	bool Simple;
1753	public:
1754	typedef EvaluatedExprVisitor<DeclExtractor> Inherited;
1755
1756	DeclExtractor(Sema &S, DeclSetVector &Decls,
1757	SmallVectorImpl<SourceRange> &Ranges) :
1758	Inherited(S.Context),
1759	Decls(Decls),
1760	Ranges(Ranges),
1761	Simple(true) {}
1762
1763	bool isSimple() { return Simple; }
1764
1765	// Replaces the method in EvaluatedExprVisitor.
1766	void VisitMemberExpr(MemberExpr* E) {
1767	Simple = false;
1768	}
1769
1770	// Any Stmt not explicitly listed will cause the condition to be marked
1771	// complex.
1772	void VisitStmt(Stmt *S) { Simple = false; }
1773
1774	void VisitBinaryOperator(BinaryOperator *E) {
1775	Visit(E->getLHS());
1776	Visit(E->getRHS());
1777	}
1778
1779	void VisitCastExpr(CastExpr *E) {
1780	Visit(E->getSubExpr());
1781	}
1782
1783	void VisitUnaryOperator(UnaryOperator *E) {
1784	// Skip checking conditionals with derefernces.
1785	if (E->getOpcode() == UO_Deref)
1786	Simple = false;
1787	else
1788	Visit(E->getSubExpr());
1789	}
1790
1791	void VisitConditionalOperator(ConditionalOperator *E) {
1792	Visit(E->getCond());
1793	Visit(E->getTrueExpr());
1794	Visit(E->getFalseExpr());
1795	}
1796
1797	void VisitParenExpr(ParenExpr *E) {
1798	Visit(E->getSubExpr());
1799	}
1800
1801	void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
1802	Visit(E->getOpaqueValue()->getSourceExpr());
1803	Visit(E->getFalseExpr());
1804	}
1805
1806	void VisitIntegerLiteral(IntegerLiteral *E) { }
1807	void VisitFloatingLiteral(FloatingLiteral *E) { }
1808	void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { }
1809	void VisitCharacterLiteral(CharacterLiteral *E) { }
1810	void VisitGNUNullExpr(GNUNullExpr *E) { }
1811	void VisitImaginaryLiteral(ImaginaryLiteral *E) { }
1812
1813	void VisitDeclRefExpr(DeclRefExpr *E) {
1814	VarDecl *VD = dyn_cast<VarDecl>(Val: E->getDecl());
1815	if (!VD) {
1816	// Don't allow unhandled Decl types.
1817	Simple = false;
1818	return;
1819	}
1820
1821	Ranges.push_back(Elt: E->getSourceRange());
1822
1823	Decls.insert(X: VD);
1824	}
1825
1826	}; // end class DeclExtractor
1827
1828	// DeclMatcher checks to see if the decls are used in a non-evaluated
1829	// context.
1830	class DeclMatcher : public EvaluatedExprVisitor<DeclMatcher> {
1831	DeclSetVector &Decls;
1832	bool FoundDecl;
1833
1834	public:
1835	typedef EvaluatedExprVisitor<DeclMatcher> Inherited;
1836
1837	DeclMatcher(Sema &S, DeclSetVector &Decls, Stmt *Statement) :
1838	Inherited(S.Context), Decls(Decls), FoundDecl(false) {
1839	if (!Statement) return;
1840
1841	Visit(S: Statement);
1842	}
1843
1844	void VisitReturnStmt(ReturnStmt *S) {
1845	FoundDecl = true;
1846	}
1847
1848	void VisitBreakStmt(BreakStmt *S) {
1849	FoundDecl = true;
1850	}
1851
1852	void VisitGotoStmt(GotoStmt *S) {
1853	FoundDecl = true;
1854	}
1855
1856	void VisitCastExpr(CastExpr *E) {
1857	if (E->getCastKind() == CK_LValueToRValue)
1858	CheckLValueToRValueCast(E: E->getSubExpr());
1859	else
1860	Visit(E->getSubExpr());
1861	}
1862
1863	void CheckLValueToRValueCast(Expr *E) {
1864	E = E->IgnoreParenImpCasts();
1865
1866	if (isa<DeclRefExpr>(Val: E)) {
1867	return;
1868	}
1869
1870	if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(Val: E)) {
1871	Visit(CO->getCond());
1872	CheckLValueToRValueCast(E: CO->getTrueExpr());
1873	CheckLValueToRValueCast(E: CO->getFalseExpr());
1874	return;
1875	}
1876
1877	if (BinaryConditionalOperator *BCO =
1878	dyn_cast<BinaryConditionalOperator>(Val: E)) {
1879	CheckLValueToRValueCast(E: BCO->getOpaqueValue()->getSourceExpr());
1880	CheckLValueToRValueCast(E: BCO->getFalseExpr());
1881	return;
1882	}
1883
1884	Visit(E);
1885	}
1886
1887	void VisitDeclRefExpr(DeclRefExpr *E) {
1888	if (VarDecl *VD = dyn_cast<VarDecl>(Val: E->getDecl()))
1889	if (Decls.count(key: VD))
1890	FoundDecl = true;
1891	}
1892
1893	void VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
1894	// Only need to visit the semantics for POE.
1895	// SyntaticForm doesn't really use the Decal.
1896	for (auto *S : POE->semantics()) {
1897	if (auto *OVE = dyn_cast<OpaqueValueExpr>(Val: S))
1898	// Look past the OVE into the expression it binds.
1899	Visit(OVE->getSourceExpr());
1900	else
1901	Visit(S);
1902	}
1903	}
1904
1905	bool FoundDeclInUse() { return FoundDecl; }
1906
1907	}; // end class DeclMatcher
1908
1909	void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
1910	Expr *Third, Stmt *Body) {
1911	// Condition is empty
1912	if (!Second) return;
1913
1914	if (S.Diags.isIgnored(diag::warn_variables_not_in_loop_body,
1915	Second->getBeginLoc()))
1916	return;
1917
1918	PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body);
1919	DeclSetVector Decls;
1920	SmallVector<SourceRange, 10> Ranges;
1921	DeclExtractor DE(S, Decls, Ranges);
1922	DE.Visit(Second);
1923
1924	// Don't analyze complex conditionals.
1925	if (!DE.isSimple()) return;
1926
1927	// No decls found.
1928	if (Decls.size() == 0) return;
1929
1930	// Don't warn on volatile, static, or global variables.
1931	for (auto *VD : Decls)
1932	if (VD->getType().isVolatileQualified() || VD->hasGlobalStorage())
1933	return;
1934
1935	if (DeclMatcher(S, Decls, Second).FoundDeclInUse() ||
1936	DeclMatcher(S, Decls, Third).FoundDeclInUse() ||
1937	DeclMatcher(S, Decls, Body).FoundDeclInUse())
1938	return;
1939
1940	// Load decl names into diagnostic.
1941	if (Decls.size() > 4) {
1942	PDiag << 0;
1943	} else {
1944	PDiag << (unsigned)Decls.size();
1945	for (auto *VD : Decls)
1946	PDiag << VD->getDeclName();
1947	}
1948
1949	for (auto Range : Ranges)
1950	PDiag << Range;
1951
1952	S.Diag(Loc: Ranges.begin()->getBegin(), PD: PDiag);
1953	}
1954
1955	// If Statement is an incemement or decrement, return true and sets the
1956	// variables Increment and DRE.
1957	bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment,
1958	DeclRefExpr *&DRE) {
1959	if (auto Cleanups = dyn_cast<ExprWithCleanups>(Val: Statement))
1960	if (!Cleanups->cleanupsHaveSideEffects())
1961	Statement = Cleanups->getSubExpr();
1962
1963	if (UnaryOperator *UO = dyn_cast<UnaryOperator>(Val: Statement)) {
1964	switch (UO->getOpcode()) {
1965	default: return false;
1966	case UO_PostInc:
1967	case UO_PreInc:
1968	Increment = true;
1969	break;
1970	case UO_PostDec:
1971	case UO_PreDec:
1972	Increment = false;
1973	break;
1974	}
1975	DRE = dyn_cast<DeclRefExpr>(Val: UO->getSubExpr());
1976	return DRE;
1977	}
1978
1979	if (CXXOperatorCallExpr *Call = dyn_cast<CXXOperatorCallExpr>(Val: Statement)) {
1980	FunctionDecl *FD = Call->getDirectCallee();
1981	if (!FD || !FD->isOverloadedOperator()) return false;
1982	switch (FD->getOverloadedOperator()) {
1983	default: return false;
1984	case OO_PlusPlus:
1985	Increment = true;
1986	break;
1987	case OO_MinusMinus:
1988	Increment = false;
1989	break;
1990	}
1991	DRE = dyn_cast<DeclRefExpr>(Call->getArg(0));
1992	return DRE;
1993	}
1994
1995	return false;
1996	}
1997
1998	// A visitor to determine if a continue or break statement is a
1999	// subexpression.
2000	class BreakContinueFinder : public ConstEvaluatedExprVisitor<BreakContinueFinder> {
2001	SourceLocation BreakLoc;
2002	SourceLocation ContinueLoc;
2003	bool InSwitch = false;
2004
2005	public:
2006	BreakContinueFinder(Sema &S, const Stmt* Body) :
2007	Inherited(S.Context) {
2008	Visit(S: Body);
2009	}
2010
2011	typedef ConstEvaluatedExprVisitor<BreakContinueFinder> Inherited;
2012
2013	void VisitContinueStmt(const ContinueStmt* E) {
2014	ContinueLoc = E->getContinueLoc();
2015	}
2016
2017	void VisitBreakStmt(const BreakStmt* E) {
2018	if (!InSwitch)
2019	BreakLoc = E->getBreakLoc();
2020	}
2021
2022	void VisitSwitchStmt(const SwitchStmt* S) {
2023	if (const Stmt *Init = S->getInit())
2024	Visit(S: Init);
2025	if (const Stmt *CondVar = S->getConditionVariableDeclStmt())
2026	Visit(S: CondVar);
2027	if (const Stmt *Cond = S->getCond())
2028	Visit(S: Cond);
2029
2030	// Don't return break statements from the body of a switch.
2031	InSwitch = true;
2032	if (const Stmt *Body = S->getBody())
2033	Visit(S: Body);
2034	InSwitch = false;
2035	}
2036
2037	void VisitForStmt(const ForStmt *S) {
2038	// Only visit the init statement of a for loop; the body
2039	// has a different break/continue scope.
2040	if (const Stmt *Init = S->getInit())
2041	Visit(S: Init);
2042	}
2043
2044	void VisitWhileStmt(const WhileStmt *) {
2045	// Do nothing; the children of a while loop have a different
2046	// break/continue scope.
2047	}
2048
2049	void VisitDoStmt(const DoStmt *) {
2050	// Do nothing; the children of a while loop have a different
2051	// break/continue scope.
2052	}
2053
2054	void VisitCXXForRangeStmt(const CXXForRangeStmt *S) {
2055	// Only visit the initialization of a for loop; the body
2056	// has a different break/continue scope.
2057	if (const Stmt *Init = S->getInit())
2058	Visit(S: Init);
2059	if (const Stmt *Range = S->getRangeStmt())
2060	Visit(S: Range);
2061	if (const Stmt *Begin = S->getBeginStmt())
2062	Visit(S: Begin);
2063	if (const Stmt *End = S->getEndStmt())
2064	Visit(S: End);
2065	}
2066
2067	void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S) {
2068	// Only visit the initialization of a for loop; the body
2069	// has a different break/continue scope.
2070	if (const Stmt *Element = S->getElement())
2071	Visit(S: Element);
2072	if (const Stmt *Collection = S->getCollection())
2073	Visit(S: Collection);
2074	}
2075
2076	bool ContinueFound() { return ContinueLoc.isValid(); }
2077	bool BreakFound() { return BreakLoc.isValid(); }
2078	SourceLocation GetContinueLoc() { return ContinueLoc; }
2079	SourceLocation GetBreakLoc() { return BreakLoc; }
2080
2081	}; // end class BreakContinueFinder
2082
2083	// Emit a warning when a loop increment/decrement appears twice per loop
2084	// iteration. The conditions which trigger this warning are:
2085	// 1) The last statement in the loop body and the third expression in the
2086	// for loop are both increment or both decrement of the same variable
2087	// 2) No continue statements in the loop body.
2088	void CheckForRedundantIteration(Sema &S, Expr *Third, Stmt *Body) {
2089	// Return when there is nothing to check.
2090	if (!Body || !Third) return;
2091
2092	if (S.Diags.isIgnored(diag::warn_redundant_loop_iteration,
2093	Third->getBeginLoc()))
2094	return;
2095
2096	// Get the last statement from the loop body.
2097	CompoundStmt *CS = dyn_cast<CompoundStmt>(Val: Body);
2098	if (!CS || CS->body_empty()) return;
2099	Stmt *LastStmt = CS->body_back();
2100	if (!LastStmt) return;
2101
2102	bool LoopIncrement, LastIncrement;
2103	DeclRefExpr *LoopDRE, *LastDRE;
2104
2105	if (!ProcessIterationStmt(S, Third, LoopIncrement, LoopDRE)) return;
2106	if (!ProcessIterationStmt(S, Statement: LastStmt, Increment&: LastIncrement, DRE&: LastDRE)) return;
2107
2108	// Check that the two statements are both increments or both decrements
2109	// on the same variable.
2110	if (LoopIncrement != LastIncrement ||
2111	LoopDRE->getDecl() != LastDRE->getDecl()) return;
2112
2113	if (BreakContinueFinder(S, Body).ContinueFound()) return;
2114
2115	S.Diag(LastDRE->getLocation(), diag::warn_redundant_loop_iteration)
2116	<< LastDRE->getDecl() << LastIncrement;
2117	S.Diag(LoopDRE->getLocation(), diag::note_loop_iteration_here)
2118	<< LoopIncrement;
2119	}
2120
2121	} // end namespace
2122
2123
2124	void Sema::CheckBreakContinueBinding(Expr *E) {
2125	if (!E || getLangOpts().CPlusPlus)
2126	return;
2127	BreakContinueFinder BCFinder(*this, E);
2128	Scope *BreakParent = CurScope->getBreakParent();
2129	if (BCFinder.BreakFound() && BreakParent) {
2130	if (BreakParent->getFlags() & Scope::SwitchScope) {
2131	Diag(BCFinder.GetBreakLoc(), diag::warn_break_binds_to_switch);
2132	} else {
2133	Diag(BCFinder.GetBreakLoc(), diag::warn_loop_ctrl_binds_to_inner)
2134	<< "break";
2135	}
2136	} else if (BCFinder.ContinueFound() && CurScope->getContinueParent()) {
2137	Diag(BCFinder.GetContinueLoc(), diag::warn_loop_ctrl_binds_to_inner)
2138	<< "continue";
2139	}
2140	}
2141
2142	StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
2143	Stmt *First, ConditionResult Second,
2144	FullExprArg third, SourceLocation RParenLoc,
2145	Stmt *Body) {
2146	if (Second.isInvalid())
2147	return StmtError();
2148
2149	if (!getLangOpts().CPlusPlus) {
2150	if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(Val: First)) {
2151	// C99 6.8.5p3: The declaration part of a 'for' statement shall only
2152	// declare identifiers for objects having storage class 'auto' or
2153	// 'register'.
2154	const Decl *NonVarSeen = nullptr;
2155	bool VarDeclSeen = false;
2156	for (auto *DI : DS->decls()) {
2157	if (VarDecl *VD = dyn_cast<VarDecl>(Val: DI)) {
2158	VarDeclSeen = true;
2159	if (VD->isLocalVarDecl() && !VD->hasLocalStorage()) {
2160	Diag(DI->getLocation(), diag::err_non_local_variable_decl_in_for);
2161	DI->setInvalidDecl();
2162	}
2163	} else if (!NonVarSeen) {
2164	// Keep track of the first non-variable declaration we saw so that
2165	// we can diagnose if we don't see any variable declarations. This
2166	// covers a case like declaring a typedef, function, or structure
2167	// type rather than a variable.
2168	NonVarSeen = DI;
2169	}
2170	}
2171	// Diagnose if we saw a non-variable declaration but no variable
2172	// declarations.
2173	if (NonVarSeen && !VarDeclSeen)
2174	Diag(NonVarSeen->getLocation(), diag::err_non_variable_decl_in_for);
2175	}
2176	}
2177
2178	CheckBreakContinueBinding(E: Second.get().second);
2179	CheckBreakContinueBinding(E: third.get());
2180
2181	if (!Second.get().first)
2182	CheckForLoopConditionalStatement(S&: *this, Second: Second.get().second, Third: third.get(),
2183	Body);
2184	CheckForRedundantIteration(S&: *this, Third: third.get(), Body);
2185
2186	if (Second.get().second &&
2187	!Diags.isIgnored(diag::warn_comma_operator,
2188	Second.get().second->getExprLoc()))
2189	CommaVisitor(*this).Visit(Second.get().second);
2190
2191	Expr *Third = third.release().getAs<Expr>();
2192	if (isa<NullStmt>(Val: Body))
2193	getCurCompoundScope().setHasEmptyLoopBodies();
2194
2195	return new (Context)
2196	ForStmt(Context, First, Second.get().second, Second.get().first, Third,
2197	Body, ForLoc, LParenLoc, RParenLoc);
2198	}
2199
2200	/// In an Objective C collection iteration statement:
2201	/// for (x in y)
2202	/// x can be an arbitrary l-value expression. Bind it up as a
2203	/// full-expression.
2204	StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
2205	// Reduce placeholder expressions here. Note that this rejects the
2206	// use of pseudo-object l-values in this position.
2207	ExprResult result = CheckPlaceholderExpr(E);
2208	if (result.isInvalid()) return StmtError();
2209	E = result.get();
2210
2211	ExprResult FullExpr = ActOnFinishFullExpr(Expr: E, /*DiscardedValue*/ false);
2212	if (FullExpr.isInvalid())
2213	return StmtError();
2214	return StmtResult(static_cast<Stmt*>(FullExpr.get()));
2215	}
2216
2217	ExprResult
2218	Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) {
2219	if (!collection)
2220	return ExprError();
2221
2222	ExprResult result = CorrectDelayedTyposInExpr(E: collection);
2223	if (!result.isUsable())
2224	return ExprError();
2225	collection = result.get();
2226
2227	// Bail out early if we've got a type-dependent expression.
2228	if (collection->isTypeDependent()) return collection;
2229
2230	// Perform normal l-value conversion.
2231	result = DefaultFunctionArrayLvalueConversion(E: collection);
2232	if (result.isInvalid())
2233	return ExprError();
2234	collection = result.get();
2235
2236	// The operand needs to have object-pointer type.
2237	// TODO: should we do a contextual conversion?
2238	const ObjCObjectPointerType *pointerType =
2239	collection->getType()->getAs<ObjCObjectPointerType>();
2240	if (!pointerType)
2241	return Diag(forLoc, diag::err_collection_expr_type)
2242	<< collection->getType() << collection->getSourceRange();
2243
2244	// Check that the operand provides
2245	// - countByEnumeratingWithState:objects:count:
2246	const ObjCObjectType *objectType = pointerType->getObjectType();
2247	ObjCInterfaceDecl *iface = objectType->getInterface();
2248
2249	// If we have a forward-declared type, we can't do this check.
2250	// Under ARC, it is an error not to have a forward-declared class.
2251	if (iface &&
2252	(getLangOpts().ObjCAutoRefCount
2253	? RequireCompleteType(forLoc, QualType(objectType, 0),
2254	diag::err_arc_collection_forward, collection)
2255	: !isCompleteType(forLoc, QualType(objectType, 0)))) {
2256	// Otherwise, if we have any useful type information, check that
2257	// the type declares the appropriate method.
2258	} else if (iface || !objectType->qual_empty()) {
2259	IdentifierInfo *selectorIdents[] = {
2260	&Context.Idents.get(Name: "countByEnumeratingWithState"),
2261	&Context.Idents.get(Name: "objects"),
2262	&Context.Idents.get(Name: "count")
2263	};
2264	Selector selector = Context.Selectors.getSelector(NumArgs: 3, IIV: &selectorIdents[0]);
2265
2266	ObjCMethodDecl *method = nullptr;
2267
2268	// If there's an interface, look in both the public and private APIs.
2269	if (iface) {
2270	method = iface->lookupInstanceMethod(Sel: selector);
2271	if (!method) method = iface->lookupPrivateMethod(Sel: selector);
2272	}
2273
2274	// Also check protocol qualifiers.
2275	if (!method)
2276	method = LookupMethodInQualifiedType(Sel: selector, OPT: pointerType,
2277	/*instance*/ IsInstance: true);
2278
2279	// If we didn't find it anywhere, give up.
2280	if (!method) {
2281	Diag(forLoc, diag::warn_collection_expr_type)
2282	<< collection->getType() << selector << collection->getSourceRange();
2283	}
2284
2285	// TODO: check for an incompatible signature?
2286	}
2287
2288	// Wrap up any cleanups in the expression.
2289	return collection;
2290	}
2291
2292	StmtResult
2293	Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
2294	Stmt *First, Expr *collection,
2295	SourceLocation RParenLoc) {
2296	setFunctionHasBranchProtectedScope();
2297
2298	ExprResult CollectionExprResult =
2299	CheckObjCForCollectionOperand(forLoc: ForLoc, collection);
2300
2301	if (First) {
2302	QualType FirstType;
2303	if (DeclStmt *DS = dyn_cast<DeclStmt>(Val: First)) {
2304	if (!DS->isSingleDecl())
2305	return StmtError(Diag((*DS->decl_begin())->getLocation(),
2306	diag::err_toomany_element_decls));
2307
2308	VarDecl *D = dyn_cast<VarDecl>(Val: DS->getSingleDecl());
2309	if (!D || D->isInvalidDecl())
2310	return StmtError();
2311
2312	FirstType = D->getType();
2313	// C99 6.8.5p3: The declaration part of a 'for' statement shall only
2314	// declare identifiers for objects having storage class 'auto' or
2315	// 'register'.
2316	if (!D->hasLocalStorage())
2317	return StmtError(Diag(D->getLocation(),
2318	diag::err_non_local_variable_decl_in_for));
2319
2320	// If the type contained 'auto', deduce the 'auto' to 'id'.
2321	if (FirstType->getContainedAutoType()) {
2322	SourceLocation Loc = D->getLocation();
2323	OpaqueValueExpr OpaqueId(Loc, Context.getObjCIdType(), VK_PRValue);
2324	Expr *DeducedInit = &OpaqueId;
2325	TemplateDeductionInfo Info(Loc);
2326	FirstType = QualType();
2327	TemplateDeductionResult Result = DeduceAutoType(
2328	AutoTypeLoc: D->getTypeSourceInfo()->getTypeLoc(), Initializer: DeducedInit, Result&: FirstType, Info);
2329	if (Result != TemplateDeductionResult::Success &&
2330	Result != TemplateDeductionResult::AlreadyDiagnosed)
2331	DiagnoseAutoDeductionFailure(VDecl: D, Init: DeducedInit);
2332	if (FirstType.isNull()) {
2333	D->setInvalidDecl();
2334	return StmtError();
2335	}
2336
2337	D->setType(FirstType);
2338
2339	if (!inTemplateInstantiation()) {
2340	SourceLocation Loc =
2341	D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
2342	Diag(Loc, diag::warn_auto_var_is_id)
2343	<< D->getDeclName();
2344	}
2345	}
2346
2347	} else {
2348	Expr *FirstE = cast<Expr>(Val: First);
2349	if (!FirstE->isTypeDependent() && !FirstE->isLValue())
2350	return StmtError(
2351	Diag(First->getBeginLoc(), diag::err_selector_element_not_lvalue)
2352	<< First->getSourceRange());
2353
2354	FirstType = static_cast<Expr*>(First)->getType();
2355	if (FirstType.isConstQualified())
2356	Diag(ForLoc, diag::err_selector_element_const_type)
2357	<< FirstType << First->getSourceRange();
2358	}
2359	if (!FirstType->isDependentType() &&
2360	!FirstType->isObjCObjectPointerType() &&
2361	!FirstType->isBlockPointerType())
2362	return StmtError(Diag(ForLoc, diag::err_selector_element_type)
2363	<< FirstType << First->getSourceRange());
2364	}
2365
2366	if (CollectionExprResult.isInvalid())
2367	return StmtError();
2368
2369	CollectionExprResult =
2370	ActOnFinishFullExpr(Expr: CollectionExprResult.get(), /*DiscardedValue*/ false);
2371	if (CollectionExprResult.isInvalid())
2372	return StmtError();
2373
2374	return new (Context) ObjCForCollectionStmt(First, CollectionExprResult.get(),
2375	nullptr, ForLoc, RParenLoc);
2376	}
2377
2378	/// Finish building a variable declaration for a for-range statement.
2379	/// \return true if an error occurs.
2380	static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
2381	SourceLocation Loc, int DiagID) {
2382	if (Decl->getType()->isUndeducedType()) {
2383	ExprResult Res = SemaRef.CorrectDelayedTyposInExpr(E: Init);
2384	if (!Res.isUsable()) {
2385	Decl->setInvalidDecl();
2386	return true;
2387	}
2388	Init = Res.get();
2389	}
2390
2391	// Deduce the type for the iterator variable now rather than leaving it to
2392	// AddInitializerToDecl, so we can produce a more suitable diagnostic.
2393	QualType InitType;
2394	if (!isa<InitListExpr>(Val: Init) && Init->getType()->isVoidType()) {
2395	SemaRef.Diag(Loc, DiagID) << Init->getType();
2396	} else {
2397	TemplateDeductionInfo Info(Init->getExprLoc());
2398	TemplateDeductionResult Result = SemaRef.DeduceAutoType(
2399	AutoTypeLoc: Decl->getTypeSourceInfo()->getTypeLoc(), Initializer: Init, Result&: InitType, Info);
2400	if (Result != TemplateDeductionResult::Success &&
2401	Result != TemplateDeductionResult::AlreadyDiagnosed)
2402	SemaRef.Diag(Loc, DiagID) << Init->getType();
2403	}
2404
2405	if (InitType.isNull()) {
2406	Decl->setInvalidDecl();
2407	return true;
2408	}
2409	Decl->setType(InitType);
2410
2411	// In ARC, infer lifetime.
2412	// FIXME: ARC may want to turn this into 'const __unsafe_unretained' if
2413	// we're doing the equivalent of fast iteration.
2414	if (SemaRef.getLangOpts().ObjCAutoRefCount &&
2415	SemaRef.inferObjCARCLifetime(Decl))
2416	Decl->setInvalidDecl();
2417
2418	SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false);
2419	SemaRef.FinalizeDeclaration(Decl);
2420	SemaRef.CurContext->addHiddenDecl(Decl);
2421	return false;
2422	}
2423
2424	namespace {
2425	// An enum to represent whether something is dealing with a call to begin()
2426	// or a call to end() in a range-based for loop.
2427	enum BeginEndFunction {
2428	BEF_begin,
2429	BEF_end
2430	};
2431
2432	/// Produce a note indicating which begin/end function was implicitly called
2433	/// by a C++11 for-range statement. This is often not obvious from the code,
2434	/// nor from the diagnostics produced when analysing the implicit expressions
2435	/// required in a for-range statement.
2436	void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
2437	BeginEndFunction BEF) {
2438	CallExpr *CE = dyn_cast<CallExpr>(Val: E);
2439	if (!CE)
2440	return;
2441	FunctionDecl *D = dyn_cast<FunctionDecl>(Val: CE->getCalleeDecl());
2442	if (!D)
2443	return;
2444	SourceLocation Loc = D->getLocation();
2445
2446	std::string Description;
2447	bool IsTemplate = false;
2448	if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) {
2449	Description = SemaRef.getTemplateArgumentBindingsText(
2450	FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs());
2451	IsTemplate = true;
2452	}
2453
2454	SemaRef.Diag(Loc, diag::note_for_range_begin_end)
2455	<< BEF << IsTemplate << Description << E->getType();
2456	}
2457
2458	/// Build a variable declaration for a for-range statement.
2459	VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
2460	QualType Type, StringRef Name) {
2461	DeclContext *DC = SemaRef.CurContext;
2462	IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
2463	TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(T: Type, Loc);
2464	VarDecl *Decl = VarDecl::Create(C&: SemaRef.Context, DC, StartLoc: Loc, IdLoc: Loc, Id: II, T: Type,
2465	TInfo, S: SC_None);
2466	Decl->setImplicit();
2467	return Decl;
2468	}
2469
2470	}
2471
2472	static bool ObjCEnumerationCollection(Expr *Collection) {
2473	return !Collection->isTypeDependent()
2474	&& Collection->getType()->getAs<ObjCObjectPointerType>() != nullptr;
2475	}
2476
2477	/// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement.
2478	///
2479	/// C++11 [stmt.ranged]:
2480	/// A range-based for statement is equivalent to
2481	///
2482	/// {
2483	/// auto && __range = range-init;
2484	/// for ( auto __begin = begin-expr,
2485	/// __end = end-expr;
2486	/// __begin != __end;
2487	/// ++__begin ) {
2488	/// for-range-declaration = *__begin;
2489	/// statement
2490	/// }
2491	/// }
2492	///
2493	/// The body of the loop is not available yet, since it cannot be analysed until
2494	/// we have determined the type of the for-range-declaration.
2495	StmtResult Sema::ActOnCXXForRangeStmt(
2496	Scope *S, SourceLocation ForLoc, SourceLocation CoawaitLoc, Stmt *InitStmt,
2497	Stmt *First, SourceLocation ColonLoc, Expr *Range, SourceLocation RParenLoc,
2498	BuildForRangeKind Kind,
2499	ArrayRef<MaterializeTemporaryExpr *> LifetimeExtendTemps) {
2500	// FIXME: recover in order to allow the body to be parsed.
2501	if (!First)
2502	return StmtError();
2503
2504	if (Range && ObjCEnumerationCollection(Collection: Range)) {
2505	// FIXME: Support init-statements in Objective-C++20 ranged for statement.
2506	if (InitStmt)
2507	return Diag(InitStmt->getBeginLoc(), diag::err_objc_for_range_init_stmt)
2508	<< InitStmt->getSourceRange();
2509	return ActOnObjCForCollectionStmt(ForLoc, First, collection: Range, RParenLoc);
2510	}
2511
2512	DeclStmt *DS = dyn_cast<DeclStmt>(Val: First);
2513	assert(DS && "first part of for range not a decl stmt");
2514
2515	if (!DS->isSingleDecl()) {
2516	Diag(DS->getBeginLoc(), diag::err_type_defined_in_for_range);
2517	return StmtError();
2518	}
2519
2520	// This function is responsible for attaching an initializer to LoopVar. We
2521	// must call ActOnInitializerError if we fail to do so.
2522	Decl *LoopVar = DS->getSingleDecl();
2523	if (LoopVar->isInvalidDecl() || !Range ||
2524	DiagnoseUnexpandedParameterPack(E: Range, UPPC: UPPC_Expression)) {
2525	ActOnInitializerError(Dcl: LoopVar);
2526	return StmtError();
2527	}
2528
2529	// Build the coroutine state immediately and not later during template
2530	// instantiation
2531	if (!CoawaitLoc.isInvalid()) {
2532	if (!ActOnCoroutineBodyStart(S, KwLoc: CoawaitLoc, Keyword: "co_await")) {
2533	ActOnInitializerError(Dcl: LoopVar);
2534	return StmtError();
2535	}
2536	}
2537
2538	// Build auto && __range = range-init
2539	// Divide by 2, since the variables are in the inner scope (loop body).
2540	const auto DepthStr = std::to_string(val: S->getDepth() / 2);
2541	SourceLocation RangeLoc = Range->getBeginLoc();
2542	VarDecl *RangeVar = BuildForRangeVarDecl(SemaRef&: *this, Loc: RangeLoc,
2543	Type: Context.getAutoRRefDeductType(),
2544	Name: std::string("__range") + DepthStr);
2545	if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
2546	diag::err_for_range_deduction_failure)) {
2547	ActOnInitializerError(Dcl: LoopVar);
2548	return StmtError();
2549	}
2550
2551	// Claim the type doesn't contain auto: we've already done the checking.
2552	DeclGroupPtrTy RangeGroup =
2553	BuildDeclaratorGroup(Group: MutableArrayRef<Decl *>((Decl **)&RangeVar, 1));
2554	StmtResult RangeDecl = ActOnDeclStmt(dg: RangeGroup, StartLoc: RangeLoc, EndLoc: RangeLoc);
2555	if (RangeDecl.isInvalid()) {
2556	ActOnInitializerError(Dcl: LoopVar);
2557	return StmtError();
2558	}
2559
2560	StmtResult R = BuildCXXForRangeStmt(
2561	ForLoc, CoawaitLoc, InitStmt, ColonLoc, RangeDecl: RangeDecl.get(),
2562	/*BeginStmt=*/Begin: nullptr, /*EndStmt=*/End: nullptr,
2563	/*Cond=*/nullptr, /*Inc=*/nullptr, LoopVarDecl: DS, RParenLoc, Kind,
2564	LifetimeExtendTemps);
2565	if (R.isInvalid()) {
2566	ActOnInitializerError(Dcl: LoopVar);
2567	return StmtError();
2568	}
2569
2570	return R;
2571	}
2572
2573	/// Create the initialization, compare, and increment steps for
2574	/// the range-based for loop expression.
2575	/// This function does not handle array-based for loops,
2576	/// which are created in Sema::BuildCXXForRangeStmt.
2577	///
2578	/// \returns a ForRangeStatus indicating success or what kind of error occurred.
2579	/// BeginExpr and EndExpr are set and FRS_Success is returned on success;
2580	/// CandidateSet and BEF are set and some non-success value is returned on
2581	/// failure.
2582	static Sema::ForRangeStatus
2583	BuildNonArrayForRange(Sema &SemaRef, Expr *BeginRange, Expr *EndRange,
2584	QualType RangeType, VarDecl *BeginVar, VarDecl *EndVar,
2585	SourceLocation ColonLoc, SourceLocation CoawaitLoc,
2586	OverloadCandidateSet *CandidateSet, ExprResult *BeginExpr,
2587	ExprResult *EndExpr, BeginEndFunction *BEF) {
2588	DeclarationNameInfo BeginNameInfo(
2589	&SemaRef.PP.getIdentifierTable().get(Name: "begin"), ColonLoc);
2590	DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get(Name: "end"),
2591	ColonLoc);
2592
2593	LookupResult BeginMemberLookup(SemaRef, BeginNameInfo,
2594	Sema::LookupMemberName);
2595	LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName);
2596
2597	auto BuildBegin = [&] {
2598	*BEF = BEF_begin;
2599	Sema::ForRangeStatus RangeStatus =
2600	SemaRef.BuildForRangeBeginEndCall(Loc: ColonLoc, RangeLoc: ColonLoc, NameInfo: BeginNameInfo,
2601	MemberLookup&: BeginMemberLookup, CandidateSet,
2602	Range: BeginRange, CallExpr: BeginExpr);
2603
2604	if (RangeStatus != Sema::FRS_Success) {
2605	if (RangeStatus == Sema::FRS_DiagnosticIssued)
2606	SemaRef.Diag(BeginRange->getBeginLoc(), diag::note_in_for_range)
2607	<< ColonLoc << BEF_begin << BeginRange->getType();
2608	return RangeStatus;
2609	}
2610	if (!CoawaitLoc.isInvalid()) {
2611	// FIXME: getCurScope() should not be used during template instantiation.
2612	// We should pick up the set of unqualified lookup results for operator
2613	// co_await during the initial parse.
2614	*BeginExpr = SemaRef.ActOnCoawaitExpr(S: SemaRef.getCurScope(), KwLoc: ColonLoc,
2615	E: BeginExpr->get());
2616	if (BeginExpr->isInvalid())
2617	return Sema::FRS_DiagnosticIssued;
2618	}
2619	if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc,
2620	diag::err_for_range_iter_deduction_failure)) {
2621	NoteForRangeBeginEndFunction(SemaRef, E: BeginExpr->get(), BEF: *BEF);
2622	return Sema::FRS_DiagnosticIssued;
2623	}
2624	return Sema::FRS_Success;
2625	};
2626
2627	auto BuildEnd = [&] {
2628	*BEF = BEF_end;
2629	Sema::ForRangeStatus RangeStatus =
2630	SemaRef.BuildForRangeBeginEndCall(Loc: ColonLoc, RangeLoc: ColonLoc, NameInfo: EndNameInfo,
2631	MemberLookup&: EndMemberLookup, CandidateSet,
2632	Range: EndRange, CallExpr: EndExpr);
2633	if (RangeStatus != Sema::FRS_Success) {
2634	if (RangeStatus == Sema::FRS_DiagnosticIssued)
2635	SemaRef.Diag(EndRange->getBeginLoc(), diag::note_in_for_range)
2636	<< ColonLoc << BEF_end << EndRange->getType();
2637	return RangeStatus;
2638	}
2639	if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc,
2640	diag::err_for_range_iter_deduction_failure)) {
2641	NoteForRangeBeginEndFunction(SemaRef, E: EndExpr->get(), BEF: *BEF);
2642	return Sema::FRS_DiagnosticIssued;
2643	}
2644	return Sema::FRS_Success;
2645	};
2646
2647	if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) {
2648	// - if _RangeT is a class type, the unqualified-ids begin and end are
2649	// looked up in the scope of class _RangeT as if by class member access
2650	// lookup (3.4.5), and if either (or both) finds at least one
2651	// declaration, begin-expr and end-expr are __range.begin() and
2652	// __range.end(), respectively;
2653	SemaRef.LookupQualifiedName(BeginMemberLookup, D);
2654	if (BeginMemberLookup.isAmbiguous())
2655	return Sema::FRS_DiagnosticIssued;
2656
2657	SemaRef.LookupQualifiedName(EndMemberLookup, D);
2658	if (EndMemberLookup.isAmbiguous())
2659	return Sema::FRS_DiagnosticIssued;
2660
2661	if (BeginMemberLookup.empty() != EndMemberLookup.empty()) {
2662	// Look up the non-member form of the member we didn't find, first.
2663	// This way we prefer a "no viable 'end'" diagnostic over a "i found
2664	// a 'begin' but ignored it because there was no member 'end'"
2665	// diagnostic.
2666	auto BuildNonmember = [&](
2667	BeginEndFunction BEFFound, LookupResult &Found,
2668	llvm::function_ref<Sema::ForRangeStatus()> BuildFound,
2669	llvm::function_ref<Sema::ForRangeStatus()> BuildNotFound) {
2670	LookupResult OldFound = std::move(Found);
2671	Found.clear();
2672
2673	if (Sema::ForRangeStatus Result = BuildNotFound())
2674	return Result;
2675
2676	switch (BuildFound()) {
2677	case Sema::FRS_Success:
2678	return Sema::FRS_Success;
2679
2680	case Sema::FRS_NoViableFunction:
2681	CandidateSet->NoteCandidates(
2682	PartialDiagnosticAt(BeginRange->getBeginLoc(),
2683	SemaRef.PDiag(diag::err_for_range_invalid)
2684	<< BeginRange->getType() << BEFFound),
2685	SemaRef, OCD_AllCandidates, BeginRange);
2686	[[fallthrough]];
2687
2688	case Sema::FRS_DiagnosticIssued:
2689	for (NamedDecl *D : OldFound) {
2690	SemaRef.Diag(D->getLocation(),
2691	diag::note_for_range_member_begin_end_ignored)
2692	<< BeginRange->getType() << BEFFound;
2693	}
2694	return Sema::FRS_DiagnosticIssued;
2695	}
2696	llvm_unreachable("unexpected ForRangeStatus");
2697	};
2698	if (BeginMemberLookup.empty())
2699	return BuildNonmember(BEF_end, EndMemberLookup, BuildEnd, BuildBegin);
2700	return BuildNonmember(BEF_begin, BeginMemberLookup, BuildBegin, BuildEnd);
2701	}
2702	} else {
2703	// - otherwise, begin-expr and end-expr are begin(__range) and
2704	// end(__range), respectively, where begin and end are looked up with
2705	// argument-dependent lookup (3.4.2). For the purposes of this name
2706	// lookup, namespace std is an associated namespace.
2707	}
2708
2709	if (Sema::ForRangeStatus Result = BuildBegin())
2710	return Result;
2711	return BuildEnd();
2712	}
2713
2714	/// Speculatively attempt to dereference an invalid range expression.
2715	/// If the attempt fails, this function will return a valid, null StmtResult
2716	/// and emit no diagnostics.
2717	static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S,
2718	SourceLocation ForLoc,
2719	SourceLocation CoawaitLoc,
2720	Stmt *InitStmt,
2721	Stmt *LoopVarDecl,
2722	SourceLocation ColonLoc,
2723	Expr *Range,
2724	SourceLocation RangeLoc,
2725	SourceLocation RParenLoc) {
2726	// Determine whether we can rebuild the for-range statement with a
2727	// dereferenced range expression.
2728	ExprResult AdjustedRange;
2729	{
2730	Sema::SFINAETrap Trap(SemaRef);
2731
2732	AdjustedRange = SemaRef.BuildUnaryOp(S, OpLoc: RangeLoc, Opc: UO_Deref, Input: Range);
2733	if (AdjustedRange.isInvalid())
2734	return StmtResult();
2735
2736	StmtResult SR = SemaRef.ActOnCXXForRangeStmt(
2737	S, ForLoc, CoawaitLoc, InitStmt, First: LoopVarDecl, ColonLoc,
2738	Range: AdjustedRange.get(), RParenLoc, Kind: Sema::BFRK_Check);
2739	if (SR.isInvalid())
2740	return StmtResult();
2741	}
2742
2743	// The attempt to dereference worked well enough that it could produce a valid
2744	// loop. Produce a fixit, and rebuild the loop with diagnostics enabled, in
2745	// case there are any other (non-fatal) problems with it.
2746	SemaRef.Diag(RangeLoc, diag::err_for_range_dereference)
2747	<< Range->getType() << FixItHint::CreateInsertion(RangeLoc, "*");
2748	return SemaRef.ActOnCXXForRangeStmt(
2749	S, ForLoc, CoawaitLoc, InitStmt, First: LoopVarDecl, ColonLoc,
2750	Range: AdjustedRange.get(), RParenLoc, Kind: Sema::BFRK_Rebuild);
2751	}
2752
2753	/// BuildCXXForRangeStmt - Build or instantiate a C++11 for-range statement.
2754	StmtResult Sema::BuildCXXForRangeStmt(
2755	SourceLocation ForLoc, SourceLocation CoawaitLoc, Stmt *InitStmt,
2756	SourceLocation ColonLoc, Stmt *RangeDecl, Stmt *Begin, Stmt *End,
2757	Expr *Cond, Expr *Inc, Stmt *LoopVarDecl, SourceLocation RParenLoc,
2758	BuildForRangeKind Kind,
2759	ArrayRef<MaterializeTemporaryExpr *> LifetimeExtendTemps) {
2760	// FIXME: This should not be used during template instantiation. We should
2761	// pick up the set of unqualified lookup results for the != and + operators
2762	// in the initial parse.
2763	//
2764	// Testcase (accepts-invalid):
2765	// template<typename T> void f() { for (auto x : T()) {} }
2766	// namespace N { struct X { X begin(); X end(); int operator*(); }; }
2767	// bool operator!=(N::X, N::X); void operator++(N::X);
2768	// void g() { f<N::X>(); }
2769	Scope *S = getCurScope();
2770
2771	DeclStmt *RangeDS = cast<DeclStmt>(Val: RangeDecl);
2772	VarDecl *RangeVar = cast<VarDecl>(Val: RangeDS->getSingleDecl());
2773	QualType RangeVarType = RangeVar->getType();
2774
2775	DeclStmt *LoopVarDS = cast<DeclStmt>(Val: LoopVarDecl);
2776	VarDecl *LoopVar = cast<VarDecl>(Val: LoopVarDS->getSingleDecl());
2777
2778	StmtResult BeginDeclStmt = Begin;
2779	StmtResult EndDeclStmt = End;
2780	ExprResult NotEqExpr = Cond, IncrExpr = Inc;
2781
2782	if (RangeVarType->isDependentType()) {
2783	// The range is implicitly used as a placeholder when it is dependent.
2784	RangeVar->markUsed(Context);
2785
2786	// Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill
2787	// them in properly when we instantiate the loop.
2788	if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
2789	if (auto *DD = dyn_cast<DecompositionDecl>(Val: LoopVar))
2790	for (auto *Binding : DD->bindings())
2791	Binding->setType(Context.DependentTy);
2792	LoopVar->setType(SubstAutoTypeDependent(TypeWithAuto: LoopVar->getType()));
2793	}
2794	} else if (!BeginDeclStmt.get()) {
2795	SourceLocation RangeLoc = RangeVar->getLocation();
2796
2797	const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
2798
2799	ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2800	VK_LValue, ColonLoc);
2801	if (BeginRangeRef.isInvalid())
2802	return StmtError();
2803
2804	ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2805	VK_LValue, ColonLoc);
2806	if (EndRangeRef.isInvalid())
2807	return StmtError();
2808
2809	QualType AutoType = Context.getAutoDeductType();
2810	Expr *Range = RangeVar->getInit();
2811	if (!Range)
2812	return StmtError();
2813	QualType RangeType = Range->getType();
2814
2815	if (RequireCompleteType(RangeLoc, RangeType,
2816	diag::err_for_range_incomplete_type))
2817	return StmtError();
2818
2819	// P2718R0 - Lifetime extension in range-based for loops.
2820	if (getLangOpts().CPlusPlus23 && !LifetimeExtendTemps.empty()) {
2821	InitializedEntity Entity =
2822	InitializedEntity::InitializeVariable(Var: RangeVar);
2823	for (auto *MTE : LifetimeExtendTemps)
2824	MTE->setExtendingDecl(RangeVar, Entity.allocateManglingNumber());
2825	}
2826
2827	// Build auto __begin = begin-expr, __end = end-expr.
2828	// Divide by 2, since the variables are in the inner scope (loop body).
2829	const auto DepthStr = std::to_string(val: S->getDepth() / 2);
2830	VarDecl *BeginVar = BuildForRangeVarDecl(SemaRef&: *this, Loc: ColonLoc, Type: AutoType,
2831	Name: std::string("__begin") + DepthStr);
2832	VarDecl *EndVar = BuildForRangeVarDecl(SemaRef&: *this, Loc: ColonLoc, Type: AutoType,
2833	Name: std::string("__end") + DepthStr);
2834
2835	// Build begin-expr and end-expr and attach to __begin and __end variables.
2836	ExprResult BeginExpr, EndExpr;
2837	if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) {
2838	// - if _RangeT is an array type, begin-expr and end-expr are __range and
2839	// __range + __bound, respectively, where __bound is the array bound. If
2840	// _RangeT is an array of unknown size or an array of incomplete type,
2841	// the program is ill-formed;
2842
2843	// begin-expr is __range.
2844	BeginExpr = BeginRangeRef;
2845	if (!CoawaitLoc.isInvalid()) {
2846	BeginExpr = ActOnCoawaitExpr(S, KwLoc: ColonLoc, E: BeginExpr.get());
2847	if (BeginExpr.isInvalid())
2848	return StmtError();
2849	}
2850	if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc,
2851	diag::err_for_range_iter_deduction_failure)) {
2852	NoteForRangeBeginEndFunction(SemaRef&: *this, E: BeginExpr.get(), BEF: BEF_begin);
2853	return StmtError();
2854	}
2855
2856	// Find the array bound.
2857	ExprResult BoundExpr;
2858	if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(Val: UnqAT))
2859	BoundExpr = IntegerLiteral::Create(
2860	C: Context, V: CAT->getSize(), type: Context.getPointerDiffType(), l: RangeLoc);
2861	else if (const VariableArrayType *VAT =
2862	dyn_cast<VariableArrayType>(Val: UnqAT)) {
2863	// For a variably modified type we can't just use the expression within
2864	// the array bounds, since we don't want that to be re-evaluated here.
2865	// Rather, we need to determine what it was when the array was first
2866	// created - so we resort to using sizeof(vla)/sizeof(element).
2867	// For e.g.
2868	// void f(int b) {
2869	// int vla[b];
2870	// b = -1; <-- This should not affect the num of iterations below
2871	// for (int &c : vla) { .. }
2872	// }
2873
2874	// FIXME: This results in codegen generating IR that recalculates the
2875	// run-time number of elements (as opposed to just using the IR Value
2876	// that corresponds to the run-time value of each bound that was
2877	// generated when the array was created.) If this proves too embarrassing
2878	// even for unoptimized IR, consider passing a magic-value/cookie to
2879	// codegen that then knows to simply use that initial llvm::Value (that
2880	// corresponds to the bound at time of array creation) within
2881	// getelementptr. But be prepared to pay the price of increasing a
2882	// customized form of coupling between the two components - which could
2883	// be hard to maintain as the codebase evolves.
2884
2885	ExprResult SizeOfVLAExprR = ActOnUnaryExprOrTypeTraitExpr(
2886	OpLoc: EndVar->getLocation(), ExprKind: UETT_SizeOf,
2887	/*IsType=*/true,
2888	TyOrEx: CreateParsedType(T: VAT->desugar(), TInfo: Context.getTrivialTypeSourceInfo(
2889	T: VAT->desugar(), Loc: RangeLoc))
2890	.getAsOpaquePtr(),
2891	ArgRange: EndVar->getSourceRange());
2892	if (SizeOfVLAExprR.isInvalid())
2893	return StmtError();
2894
2895	ExprResult SizeOfEachElementExprR = ActOnUnaryExprOrTypeTraitExpr(
2896	OpLoc: EndVar->getLocation(), ExprKind: UETT_SizeOf,
2897	/*IsType=*/true,
2898	TyOrEx: CreateParsedType(T: VAT->desugar(),
2899	TInfo: Context.getTrivialTypeSourceInfo(
2900	T: VAT->getElementType(), Loc: RangeLoc))
2901	.getAsOpaquePtr(),
2902	ArgRange: EndVar->getSourceRange());
2903	if (SizeOfEachElementExprR.isInvalid())
2904	return StmtError();
2905
2906	BoundExpr =
2907	ActOnBinOp(S, TokLoc: EndVar->getLocation(), Kind: tok::slash,
2908	LHSExpr: SizeOfVLAExprR.get(), RHSExpr: SizeOfEachElementExprR.get());
2909	if (BoundExpr.isInvalid())
2910	return StmtError();
2911
2912	} else {
2913	// Can't be a DependentSizedArrayType or an IncompleteArrayType since
2914	// UnqAT is not incomplete and Range is not type-dependent.
2915	llvm_unreachable("Unexpected array type in for-range");
2916	}
2917
2918	// end-expr is __range + __bound.
2919	EndExpr = ActOnBinOp(S, TokLoc: ColonLoc, Kind: tok::plus, LHSExpr: EndRangeRef.get(),
2920	RHSExpr: BoundExpr.get());
2921	if (EndExpr.isInvalid())
2922	return StmtError();
2923	if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc,
2924	diag::err_for_range_iter_deduction_failure)) {
2925	NoteForRangeBeginEndFunction(SemaRef&: *this, E: EndExpr.get(), BEF: BEF_end);
2926	return StmtError();
2927	}
2928	} else {
2929	OverloadCandidateSet CandidateSet(RangeLoc,
2930	OverloadCandidateSet::CSK_Normal);
2931	BeginEndFunction BEFFailure;
2932	ForRangeStatus RangeStatus = BuildNonArrayForRange(
2933	SemaRef&: *this, BeginRange: BeginRangeRef.get(), EndRange: EndRangeRef.get(), RangeType, BeginVar,
2934	EndVar, ColonLoc, CoawaitLoc, CandidateSet: &CandidateSet, BeginExpr: &BeginExpr, EndExpr: &EndExpr,
2935	BEF: &BEFFailure);
2936
2937	if (Kind == BFRK_Build && RangeStatus == FRS_NoViableFunction &&
2938	BEFFailure == BEF_begin) {
2939	// If the range is being built from an array parameter, emit a
2940	// a diagnostic that it is being treated as a pointer.
2941	if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Val: Range)) {
2942	if (ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(Val: DRE->getDecl())) {
2943	QualType ArrayTy = PVD->getOriginalType();
2944	QualType PointerTy = PVD->getType();
2945	if (PointerTy->isPointerType() && ArrayTy->isArrayType()) {
2946	Diag(Range->getBeginLoc(), diag::err_range_on_array_parameter)
2947	<< RangeLoc << PVD << ArrayTy << PointerTy;
2948	Diag(PVD->getLocation(), diag::note_declared_at);
2949	return StmtError();
2950	}
2951	}
2952	}
2953
2954	// If building the range failed, try dereferencing the range expression
2955	// unless a diagnostic was issued or the end function is problematic.
2956	StmtResult SR = RebuildForRangeWithDereference(SemaRef&: *this, S, ForLoc,
2957	CoawaitLoc, InitStmt,
2958	LoopVarDecl, ColonLoc,
2959	Range, RangeLoc,
2960	RParenLoc);
2961	if (SR.isInvalid() || SR.isUsable())
2962	return SR;
2963	}
2964
2965	// Otherwise, emit diagnostics if we haven't already.
2966	if (RangeStatus == FRS_NoViableFunction) {
2967	Expr *Range = BEFFailure ? EndRangeRef.get() : BeginRangeRef.get();
2968	CandidateSet.NoteCandidates(
2969	PartialDiagnosticAt(Range->getBeginLoc(),
2970	PDiag(diag::err_for_range_invalid)
2971	<< RangeLoc << Range->getType()
2972	<< BEFFailure),
2973	*this, OCD_AllCandidates, Range);
2974	}
2975	// Return an error if no fix was discovered.
2976	if (RangeStatus != FRS_Success)
2977	return StmtError();
2978	}
2979
2980	assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() &&
2981	"invalid range expression in for loop");
2982
2983	// C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same.
2984	// C++1z removes this restriction.
2985	QualType BeginType = BeginVar->getType(), EndType = EndVar->getType();
2986	if (!Context.hasSameType(T1: BeginType, T2: EndType)) {
2987	Diag(RangeLoc, getLangOpts().CPlusPlus17
2988	? diag::warn_for_range_begin_end_types_differ
2989	: diag::ext_for_range_begin_end_types_differ)
2990	<< BeginType << EndType;
2991	NoteForRangeBeginEndFunction(SemaRef&: *this, E: BeginExpr.get(), BEF: BEF_begin);
2992	NoteForRangeBeginEndFunction(SemaRef&: *this, E: EndExpr.get(), BEF: BEF_end);
2993	}
2994
2995	BeginDeclStmt =
2996	ActOnDeclStmt(dg: ConvertDeclToDeclGroup(BeginVar), StartLoc: ColonLoc, EndLoc: ColonLoc);
2997	EndDeclStmt =
2998	ActOnDeclStmt(dg: ConvertDeclToDeclGroup(EndVar), StartLoc: ColonLoc, EndLoc: ColonLoc);
2999
3000	const QualType BeginRefNonRefType = BeginType.getNonReferenceType();
3001	ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
3002	VK_LValue, ColonLoc);
3003	if (BeginRef.isInvalid())
3004	return StmtError();
3005
3006	ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(),
3007	VK_LValue, ColonLoc);
3008	if (EndRef.isInvalid())
3009	return StmtError();
3010
3011	// Build and check __begin != __end expression.
3012	NotEqExpr = ActOnBinOp(S, TokLoc: ColonLoc, Kind: tok::exclaimequal,
3013	LHSExpr: BeginRef.get(), RHSExpr: EndRef.get());
3014	if (!NotEqExpr.isInvalid())
3015	NotEqExpr = CheckBooleanCondition(Loc: ColonLoc, E: NotEqExpr.get());
3016	if (!NotEqExpr.isInvalid())
3017	NotEqExpr =
3018	ActOnFinishFullExpr(Expr: NotEqExpr.get(), /*DiscardedValue*/ false);
3019	if (NotEqExpr.isInvalid()) {
3020	Diag(RangeLoc, diag::note_for_range_invalid_iterator)
3021	<< RangeLoc << 0 << BeginRangeRef.get()->getType();
3022	NoteForRangeBeginEndFunction(SemaRef&: *this, E: BeginExpr.get(), BEF: BEF_begin);
3023	if (!Context.hasSameType(T1: BeginType, T2: EndType))
3024	NoteForRangeBeginEndFunction(SemaRef&: *this, E: EndExpr.get(), BEF: BEF_end);
3025	return StmtError();
3026	}
3027
3028	// Build and check ++__begin expression.
3029	BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
3030	VK_LValue, ColonLoc);
3031	if (BeginRef.isInvalid())
3032	return StmtError();
3033
3034	IncrExpr = ActOnUnaryOp(S, OpLoc: ColonLoc, Op: tok::plusplus, Input: BeginRef.get());
3035	if (!IncrExpr.isInvalid() && CoawaitLoc.isValid())
3036	// FIXME: getCurScope() should not be used during template instantiation.
3037	// We should pick up the set of unqualified lookup results for operator
3038	// co_await during the initial parse.
3039	IncrExpr = ActOnCoawaitExpr(S, KwLoc: CoawaitLoc, E: IncrExpr.get());
3040	if (!IncrExpr.isInvalid())
3041	IncrExpr = ActOnFinishFullExpr(Expr: IncrExpr.get(), /*DiscardedValue*/ false);
3042	if (IncrExpr.isInvalid()) {
3043	Diag(RangeLoc, diag::note_for_range_invalid_iterator)
3044	<< RangeLoc << 2 << BeginRangeRef.get()->getType() ;
3045	NoteForRangeBeginEndFunction(SemaRef&: *this, E: BeginExpr.get(), BEF: BEF_begin);
3046	return StmtError();
3047	}
3048
3049	// Build and check *__begin expression.
3050	BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
3051	VK_LValue, ColonLoc);
3052	if (BeginRef.isInvalid())
3053	return StmtError();
3054
3055	ExprResult DerefExpr = ActOnUnaryOp(S, OpLoc: ColonLoc, Op: tok::star, Input: BeginRef.get());
3056	if (DerefExpr.isInvalid()) {
3057	Diag(RangeLoc, diag::note_for_range_invalid_iterator)
3058	<< RangeLoc << 1 << BeginRangeRef.get()->getType();
3059	NoteForRangeBeginEndFunction(SemaRef&: *this, E: BeginExpr.get(), BEF: BEF_begin);
3060	return StmtError();
3061	}
3062
3063	// Attach *__begin as initializer for VD. Don't touch it if we're just
3064	// trying to determine whether this would be a valid range.
3065	if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
3066	AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false);
3067	if (LoopVar->isInvalidDecl() ||
3068	(LoopVar->getInit() && LoopVar->getInit()->containsErrors()))
3069	NoteForRangeBeginEndFunction(SemaRef&: *this, E: BeginExpr.get(), BEF: BEF_begin);
3070	}
3071	}
3072
3073	// Don't bother to actually allocate the result if we're just trying to
3074	// determine whether it would be valid.
3075	if (Kind == BFRK_Check)
3076	return StmtResult();
3077
3078	// In OpenMP loop region loop control variable must be private. Perform
3079	// analysis of first part (if any).
3080	if (getLangOpts().OpenMP >= 50 && BeginDeclStmt.isUsable())
3081	ActOnOpenMPLoopInitialization(ForLoc, Init: BeginDeclStmt.get());
3082
3083	return new (Context) CXXForRangeStmt(
3084	InitStmt, RangeDS, cast_or_null<DeclStmt>(Val: BeginDeclStmt.get()),
3085	cast_or_null<DeclStmt>(Val: EndDeclStmt.get()), NotEqExpr.get(),
3086	IncrExpr.get(), LoopVarDS, /*Body=*/nullptr, ForLoc, CoawaitLoc,
3087	ColonLoc, RParenLoc);
3088	}
3089
3090	/// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach
3091	/// statement.
3092	StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) {
3093	if (!S || !B)
3094	return StmtError();
3095	ObjCForCollectionStmt * ForStmt = cast<ObjCForCollectionStmt>(Val: S);
3096
3097	ForStmt->setBody(B);
3098	return S;
3099	}
3100
3101	// Warn when the loop variable is a const reference that creates a copy.
3102	// Suggest using the non-reference type for copies. If a copy can be prevented
3103	// suggest the const reference type that would do so.
3104	// For instance, given "for (const &Foo : Range)", suggest
3105	// "for (const Foo : Range)" to denote a copy is made for the loop. If
3106	// possible, also suggest "for (const &Bar : Range)" if this type prevents
3107	// the copy altogether.
3108	static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef,
3109	const VarDecl *VD,
3110	QualType RangeInitType) {
3111	const Expr *InitExpr = VD->getInit();
3112	if (!InitExpr)
3113	return;
3114
3115	QualType VariableType = VD->getType();
3116
3117	if (auto Cleanups = dyn_cast<ExprWithCleanups>(Val: InitExpr))
3118	if (!Cleanups->cleanupsHaveSideEffects())
3119	InitExpr = Cleanups->getSubExpr();
3120
3121	const MaterializeTemporaryExpr *MTE =
3122	dyn_cast<MaterializeTemporaryExpr>(Val: InitExpr);
3123
3124	// No copy made.
3125	if (!MTE)
3126	return;
3127
3128	const Expr *E = MTE->getSubExpr()->IgnoreImpCasts();
3129
3130	// Searching for either UnaryOperator for dereference of a pointer or
3131	// CXXOperatorCallExpr for handling iterators.
3132	while (!isa<CXXOperatorCallExpr>(Val: E) && !isa<UnaryOperator>(Val: E)) {
3133	if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(Val: E)) {
3134	E = CCE->getArg(Arg: 0);
3135	} else if (const CXXMemberCallExpr *Call = dyn_cast<CXXMemberCallExpr>(Val: E)) {
3136	const MemberExpr *ME = cast<MemberExpr>(Call->getCallee());
3137	E = ME->getBase();
3138	} else {
3139	const MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(Val: E);
3140	E = MTE->getSubExpr();
3141	}
3142	E = E->IgnoreImpCasts();
3143	}
3144
3145	QualType ReferenceReturnType;
3146	if (isa<UnaryOperator>(Val: E)) {
3147	ReferenceReturnType = SemaRef.Context.getLValueReferenceType(T: E->getType());
3148	} else {
3149	const CXXOperatorCallExpr *Call = cast<CXXOperatorCallExpr>(Val: E);
3150	const FunctionDecl *FD = Call->getDirectCallee();
3151	QualType ReturnType = FD->getReturnType();
3152	if (ReturnType->isReferenceType())
3153	ReferenceReturnType = ReturnType;
3154	}
3155
3156	if (!ReferenceReturnType.isNull()) {
3157	// Loop variable creates a temporary. Suggest either to go with
3158	// non-reference loop variable to indicate a copy is made, or
3159	// the correct type to bind a const reference.
3160	SemaRef.Diag(VD->getLocation(),
3161	diag::warn_for_range_const_ref_binds_temp_built_from_ref)
3162	<< VD << VariableType << ReferenceReturnType;
3163	QualType NonReferenceType = VariableType.getNonReferenceType();
3164	NonReferenceType.removeLocalConst();
3165	QualType NewReferenceType =
3166	SemaRef.Context.getLValueReferenceType(T: E->getType().withConst());
3167	SemaRef.Diag(VD->getBeginLoc(), diag::note_use_type_or_non_reference)
3168	<< NonReferenceType << NewReferenceType << VD->getSourceRange()
3169	<< FixItHint::CreateRemoval(VD->getTypeSpecEndLoc());
3170	} else if (!VariableType->isRValueReferenceType()) {
3171	// The range always returns a copy, so a temporary is always created.
3172	// Suggest removing the reference from the loop variable.
3173	// If the type is a rvalue reference do not warn since that changes the
3174	// semantic of the code.
3175	SemaRef.Diag(VD->getLocation(), diag::warn_for_range_ref_binds_ret_temp)
3176	<< VD << RangeInitType;
3177	QualType NonReferenceType = VariableType.getNonReferenceType();
3178	NonReferenceType.removeLocalConst();
3179	SemaRef.Diag(VD->getBeginLoc(), diag::note_use_non_reference_type)
3180	<< NonReferenceType << VD->getSourceRange()
3181	<< FixItHint::CreateRemoval(VD->getTypeSpecEndLoc());
3182	}
3183	}
3184
3185	/// Determines whether the @p VariableType's declaration is a record with the
3186	/// clang::trivial_abi attribute.
3187	static bool hasTrivialABIAttr(QualType VariableType) {
3188	if (CXXRecordDecl *RD = VariableType->getAsCXXRecordDecl())
3189	return RD->hasAttr<TrivialABIAttr>();
3190
3191	return false;
3192	}
3193
3194	// Warns when the loop variable can be changed to a reference type to
3195	// prevent a copy. For instance, if given "for (const Foo x : Range)" suggest
3196	// "for (const Foo &x : Range)" if this form does not make a copy.
3197	static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef,
3198	const VarDecl *VD) {
3199	const Expr *InitExpr = VD->getInit();
3200	if (!InitExpr)
3201	return;
3202
3203	QualType VariableType = VD->getType();
3204
3205	if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(Val: InitExpr)) {
3206	if (!CE->getConstructor()->isCopyConstructor())
3207	return;
3208	} else if (const CastExpr *CE = dyn_cast<CastExpr>(Val: InitExpr)) {
3209	if (CE->getCastKind() != CK_LValueToRValue)
3210	return;
3211	} else {
3212	return;
3213	}
3214
3215	// Small trivially copyable types are cheap to copy. Do not emit the
3216	// diagnostic for these instances. 64 bytes is a common size of a cache line.
3217	// (The function `getTypeSize` returns the size in bits.)
3218	ASTContext &Ctx = SemaRef.Context;
3219	if (Ctx.getTypeSize(T: VariableType) <= 64 * 8 &&
3220	(VariableType.isTriviallyCopyConstructibleType(Context: Ctx) ||
3221	hasTrivialABIAttr(VariableType)))
3222	return;
3223
3224	// Suggest changing from a const variable to a const reference variable
3225	// if doing so will prevent a copy.
3226	SemaRef.Diag(VD->getLocation(), diag::warn_for_range_copy)
3227	<< VD << VariableType;
3228	SemaRef.Diag(VD->getBeginLoc(), diag::note_use_reference_type)
3229	<< SemaRef.Context.getLValueReferenceType(VariableType)
3230	<< VD->getSourceRange()
3231	<< FixItHint::CreateInsertion(VD->getLocation(), "&");
3232	}
3233
3234	/// DiagnoseForRangeVariableCopies - Diagnose three cases and fixes for them.
3235	/// 1) for (const foo &x : foos) where foos only returns a copy. Suggest
3236	/// using "const foo x" to show that a copy is made
3237	/// 2) for (const bar &x : foos) where bar is a temporary initialized by bar.
3238	/// Suggest either "const bar x" to keep the copying or "const foo& x" to
3239	/// prevent the copy.
3240	/// 3) for (const foo x : foos) where x is constructed from a reference foo.
3241	/// Suggest "const foo &x" to prevent the copy.
3242	static void DiagnoseForRangeVariableCopies(Sema &SemaRef,
3243	const CXXForRangeStmt *ForStmt) {
3244	if (SemaRef.inTemplateInstantiation())
3245	return;
3246
3247	if (SemaRef.Diags.isIgnored(
3248	diag::warn_for_range_const_ref_binds_temp_built_from_ref,
3249	ForStmt->getBeginLoc()) &&
3250	SemaRef.Diags.isIgnored(diag::warn_for_range_ref_binds_ret_temp,
3251	ForStmt->getBeginLoc()) &&
3252	SemaRef.Diags.isIgnored(diag::warn_for_range_copy,
3253	ForStmt->getBeginLoc())) {
3254	return;
3255	}
3256
3257	const VarDecl *VD = ForStmt->getLoopVariable();
3258	if (!VD)
3259	return;
3260
3261	QualType VariableType = VD->getType();
3262
3263	if (VariableType->isIncompleteType())
3264	return;
3265
3266	const Expr *InitExpr = VD->getInit();
3267	if (!InitExpr)
3268	return;
3269
3270	if (InitExpr->getExprLoc().isMacroID())
3271	return;
3272
3273	if (VariableType->isReferenceType()) {
3274	DiagnoseForRangeReferenceVariableCopies(SemaRef, VD,
3275	RangeInitType: ForStmt->getRangeInit()->getType());
3276	} else if (VariableType.isConstQualified()) {
3277	DiagnoseForRangeConstVariableCopies(SemaRef, VD);
3278	}
3279	}
3280
3281	/// FinishCXXForRangeStmt - Attach the body to a C++0x for-range statement.
3282	/// This is a separate step from ActOnCXXForRangeStmt because analysis of the
3283	/// body cannot be performed until after the type of the range variable is
3284	/// determined.
3285	StmtResult Sema::FinishCXXForRangeStmt(Stmt *S, Stmt *B) {
3286	if (!S || !B)
3287	return StmtError();
3288
3289	if (isa<ObjCForCollectionStmt>(Val: S))
3290	return FinishObjCForCollectionStmt(S, B);
3291
3292	CXXForRangeStmt *ForStmt = cast<CXXForRangeStmt>(Val: S);
3293	ForStmt->setBody(B);
3294
3295	DiagnoseEmptyStmtBody(ForStmt->getRParenLoc(), B,
3296	diag::warn_empty_range_based_for_body);
3297
3298	DiagnoseForRangeVariableCopies(SemaRef&: *this, ForStmt);
3299
3300	return S;
3301	}
3302
3303	StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc,
3304	SourceLocation LabelLoc,
3305	LabelDecl *TheDecl) {
3306	setFunctionHasBranchIntoScope();
3307	TheDecl->markUsed(Context);
3308	return new (Context) GotoStmt(TheDecl, GotoLoc, LabelLoc);
3309	}
3310
3311	StmtResult
3312	Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
3313	Expr *E) {
3314	// Convert operand to void*
3315	if (!E->isTypeDependent()) {
3316	QualType ETy = E->getType();
3317	QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
3318	ExprResult ExprRes = E;
3319	AssignConvertType ConvTy =
3320	CheckSingleAssignmentConstraints(LHSType: DestTy, RHS&: ExprRes);
3321	if (ExprRes.isInvalid())
3322	return StmtError();
3323	E = ExprRes.get();
3324	if (DiagnoseAssignmentResult(ConvTy, Loc: StarLoc, DstType: DestTy, SrcType: ETy, SrcExpr: E, Action: AA_Passing))
3325	return StmtError();
3326	}
3327
3328	ExprResult ExprRes = ActOnFinishFullExpr(Expr: E, /*DiscardedValue*/ false);
3329	if (ExprRes.isInvalid())
3330	return StmtError();
3331	E = ExprRes.get();
3332
3333	setFunctionHasIndirectGoto();
3334
3335	return new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E);
3336	}
3337
3338	static void CheckJumpOutOfSEHFinally(Sema &S, SourceLocation Loc,
3339	const Scope &DestScope) {
3340	if (!S.CurrentSEHFinally.empty() &&
3341	DestScope.Contains(rhs: *S.CurrentSEHFinally.back())) {
3342	S.Diag(Loc, diag::warn_jump_out_of_seh_finally);
3343	}
3344	}
3345
3346	StmtResult
3347	Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
3348	Scope *S = CurScope->getContinueParent();
3349	if (!S) {
3350	// C99 6.8.6.2p1: A break shall appear only in or as a loop body.
3351	return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
3352	}
3353	if (S->isConditionVarScope()) {
3354	// We cannot 'continue;' from within a statement expression in the
3355	// initializer of a condition variable because we would jump past the
3356	// initialization of that variable.
3357	return StmtError(Diag(ContinueLoc, diag::err_continue_from_cond_var_init));
3358	}
3359	CheckJumpOutOfSEHFinally(S&: *this, Loc: ContinueLoc, DestScope: *S);
3360
3361	return new (Context) ContinueStmt(ContinueLoc);
3362	}
3363
3364	StmtResult
3365	Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
3366	Scope *S = CurScope->getBreakParent();
3367	if (!S) {
3368	// C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
3369	return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
3370	}
3371	if (S->isOpenMPLoopScope())
3372	return StmtError(Diag(BreakLoc, diag::err_omp_loop_cannot_use_stmt)
3373	<< "break");
3374	CheckJumpOutOfSEHFinally(S&: *this, Loc: BreakLoc, DestScope: *S);
3375
3376	return new (Context) BreakStmt(BreakLoc);
3377	}
3378
3379	/// Determine whether the given expression might be move-eligible or
3380	/// copy-elidable in either a (co_)return statement or throw expression,
3381	/// without considering function return type, if applicable.
3382	///
3383	/// \param E The expression being returned from the function or block,
3384	/// being thrown, or being co_returned from a coroutine. This expression
3385	/// might be modified by the implementation.
3386	///
3387	/// \param Mode Overrides detection of current language mode
3388	/// and uses the rules for C++23.
3389	///
3390	/// \returns An aggregate which contains the Candidate and isMoveEligible
3391	/// and isCopyElidable methods. If Candidate is non-null, it means
3392	/// isMoveEligible() would be true under the most permissive language standard.
3393	Sema::NamedReturnInfo Sema::getNamedReturnInfo(Expr *&E,
3394	SimplerImplicitMoveMode Mode) {
3395	if (!E)
3396	return NamedReturnInfo();
3397	// - in a return statement in a function [where] ...
3398	// ... the expression is the name of a non-volatile automatic object ...
3399	const auto *DR = dyn_cast<DeclRefExpr>(Val: E->IgnoreParens());
3400	if (!DR || DR->refersToEnclosingVariableOrCapture())
3401	return NamedReturnInfo();
3402	const auto *VD = dyn_cast<VarDecl>(Val: DR->getDecl());
3403	if (!VD)
3404	return NamedReturnInfo();
3405	if (VD->getInit() && VD->getInit()->containsErrors())
3406	return NamedReturnInfo();
3407	NamedReturnInfo Res = getNamedReturnInfo(VD);
3408	if (Res.Candidate && !E->isXValue() &&
3409	(Mode == SimplerImplicitMoveMode::ForceOn ||
3410	(Mode != SimplerImplicitMoveMode::ForceOff &&
3411	getLangOpts().CPlusPlus23))) {
3412	E = ImplicitCastExpr::Create(Context, T: VD->getType().getNonReferenceType(),
3413	Kind: CK_NoOp, Operand: E, BasePath: nullptr, Cat: VK_XValue,
3414	FPO: FPOptionsOverride());
3415	}
3416	return Res;
3417	}
3418
3419	/// Determine whether the given NRVO candidate variable is move-eligible or
3420	/// copy-elidable, without considering function return type.
3421	///
3422	/// \param VD The NRVO candidate variable.
3423	///
3424	/// \returns An aggregate which contains the Candidate and isMoveEligible
3425	/// and isCopyElidable methods. If Candidate is non-null, it means
3426	/// isMoveEligible() would be true under the most permissive language standard.
3427	Sema::NamedReturnInfo Sema::getNamedReturnInfo(const VarDecl *VD) {
3428	NamedReturnInfo Info{.Candidate: VD, .S: NamedReturnInfo::MoveEligibleAndCopyElidable};
3429
3430	// C++20 [class.copy.elision]p3:
3431	// - in a return statement in a function with ...
3432	// (other than a function ... parameter)
3433	if (VD->getKind() == Decl::ParmVar)
3434	Info.S = NamedReturnInfo::MoveEligible;
3435	else if (VD->getKind() != Decl::Var)
3436	return NamedReturnInfo();
3437
3438	// (other than ... a catch-clause parameter)
3439	if (VD->isExceptionVariable())
3440	Info.S = NamedReturnInfo::MoveEligible;
3441
3442	// ...automatic...
3443	if (!VD->hasLocalStorage())
3444	return NamedReturnInfo();
3445
3446	// We don't want to implicitly move out of a __block variable during a return
3447	// because we cannot assume the variable will no longer be used.
3448	if (VD->hasAttr<BlocksAttr>())
3449	return NamedReturnInfo();
3450
3451	QualType VDType = VD->getType();
3452	if (VDType->isObjectType()) {
3453	// C++17 [class.copy.elision]p3:
3454	// ...non-volatile automatic object...
3455	if (VDType.isVolatileQualified())
3456	return NamedReturnInfo();
3457	} else if (VDType->isRValueReferenceType()) {
3458	// C++20 [class.copy.elision]p3:
3459	// ...either a non-volatile object or an rvalue reference to a non-volatile
3460	// object type...
3461	QualType VDReferencedType = VDType.getNonReferenceType();
3462	if (VDReferencedType.isVolatileQualified() ||
3463	!VDReferencedType->isObjectType())
3464	return NamedReturnInfo();
3465	Info.S = NamedReturnInfo::MoveEligible;
3466	} else {
3467	return NamedReturnInfo();
3468	}
3469
3470	// Variables with higher required alignment than their type's ABI
3471	// alignment cannot use NRVO.
3472	if (!VD->hasDependentAlignment() &&
3473	Context.getDeclAlign(VD) > Context.getTypeAlignInChars(T: VDType))
3474	Info.S = NamedReturnInfo::MoveEligible;
3475
3476	return Info;
3477	}
3478
3479	/// Updates given NamedReturnInfo's move-eligible and
3480	/// copy-elidable statuses, considering the function
3481	/// return type criteria as applicable to return statements.
3482	///
3483	/// \param Info The NamedReturnInfo object to update.
3484	///
3485	/// \param ReturnType This is the return type of the function.
3486	/// \returns The copy elision candidate, in case the initial return expression
3487	/// was copy elidable, or nullptr otherwise.
3488	const VarDecl *Sema::getCopyElisionCandidate(NamedReturnInfo &Info,
3489	QualType ReturnType) {
3490	if (!Info.Candidate)
3491	return nullptr;
3492
3493	auto invalidNRVO = [&] {
3494	Info = NamedReturnInfo();
3495	return nullptr;
3496	};
3497
3498	// If we got a non-deduced auto ReturnType, we are in a dependent context and
3499	// there is no point in allowing copy elision since we won't have it deduced
3500	// by the point the VardDecl is instantiated, which is the last chance we have
3501	// of deciding if the candidate is really copy elidable.
3502	if ((ReturnType->getTypeClass() == Type::TypeClass::Auto &&
3503	ReturnType->isCanonicalUnqualified()) ||
3504	ReturnType->isSpecificBuiltinType(BuiltinType::Dependent))
3505	return invalidNRVO();
3506
3507	if (!ReturnType->isDependentType()) {
3508	// - in a return statement in a function with ...
3509	// ... a class return type ...
3510	if (!ReturnType->isRecordType())
3511	return invalidNRVO();
3512
3513	QualType VDType = Info.Candidate->getType();
3514	// ... the same cv-unqualified type as the function return type ...
3515	// When considering moving this expression out, allow dissimilar types.
3516	if (!VDType->isDependentType() &&
3517	!Context.hasSameUnqualifiedType(T1: ReturnType, T2: VDType))
3518	Info.S = NamedReturnInfo::MoveEligible;
3519	}
3520	return Info.isCopyElidable() ? Info.Candidate : nullptr;
3521	}
3522
3523	/// Verify that the initialization sequence that was picked for the
3524	/// first overload resolution is permissible under C++98.
3525	///
3526	/// Reject (possibly converting) constructors not taking an rvalue reference,
3527	/// or user conversion operators which are not ref-qualified.
3528	static bool
3529	VerifyInitializationSequenceCXX98(const Sema &S,
3530	const InitializationSequence &Seq) {
3531	const auto *Step = llvm::find_if(Range: Seq.steps(), P: [](const auto &Step) {
3532	return Step.Kind == InitializationSequence::SK_ConstructorInitialization ||
3533	Step.Kind == InitializationSequence::SK_UserConversion;
3534	});
3535	if (Step != Seq.step_end()) {
3536	const auto *FD = Step->Function.Function;
3537	if (isa<CXXConstructorDecl>(Val: FD)
3538	? !FD->getParamDecl(i: 0)->getType()->isRValueReferenceType()
3539	: cast<CXXMethodDecl>(Val: FD)->getRefQualifier() == RQ_None)
3540	return false;
3541	}
3542	return true;
3543	}
3544
3545	/// Perform the initialization of a potentially-movable value, which
3546	/// is the result of return value.
3547	///
3548	/// This routine implements C++20 [class.copy.elision]p3, which attempts to
3549	/// treat returned lvalues as rvalues in certain cases (to prefer move
3550	/// construction), then falls back to treating them as lvalues if that failed.
3551	ExprResult Sema::PerformMoveOrCopyInitialization(
3552	const InitializedEntity &Entity, const NamedReturnInfo &NRInfo, Expr *Value,
3553	bool SupressSimplerImplicitMoves) {
3554	if (getLangOpts().CPlusPlus &&
3555	(!getLangOpts().CPlusPlus23 || SupressSimplerImplicitMoves) &&
3556	NRInfo.isMoveEligible()) {
3557	ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(),
3558	CK_NoOp, Value, VK_XValue, FPOptionsOverride());
3559	Expr *InitExpr = &AsRvalue;
3560	auto Kind = InitializationKind::CreateCopy(InitLoc: Value->getBeginLoc(),
3561	EqualLoc: Value->getBeginLoc());
3562	InitializationSequence Seq(*this, Entity, Kind, InitExpr);
3563	auto Res = Seq.getFailedOverloadResult();
3564	if ((Res == OR_Success || Res == OR_Deleted) &&
3565	(getLangOpts().CPlusPlus11 ||
3566	VerifyInitializationSequenceCXX98(S: *this, Seq))) {
3567	// Promote "AsRvalue" to the heap, since we now need this
3568	// expression node to persist.
3569	Value =
3570	ImplicitCastExpr::Create(Context, T: Value->getType(), Kind: CK_NoOp, Operand: Value,
3571	BasePath: nullptr, Cat: VK_XValue, FPO: FPOptionsOverride());
3572	// Complete type-checking the initialization of the return type
3573	// using the constructor we found.
3574	return Seq.Perform(S&: *this, Entity, Kind: Kind, Args: Value);
3575	}
3576	}
3577	// Either we didn't meet the criteria for treating an lvalue as an rvalue,
3578	// above, or overload resolution failed. Either way, we need to try
3579	// (again) now with the return value expression as written.
3580	return PerformCopyInitialization(Entity, EqualLoc: SourceLocation(), Init: Value);
3581	}
3582
3583	/// Determine whether the declared return type of the specified function
3584	/// contains 'auto'.
3585	static bool hasDeducedReturnType(FunctionDecl *FD) {
3586	const FunctionProtoType *FPT =
3587	FD->getTypeSourceInfo()->getType()->castAs<FunctionProtoType>();
3588	return FPT->getReturnType()->isUndeducedType();
3589	}
3590
3591	/// ActOnCapScopeReturnStmt - Utility routine to type-check return statements
3592	/// for capturing scopes.
3593	///
3594	StmtResult Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc,
3595	Expr *RetValExp,
3596	NamedReturnInfo &NRInfo,
3597	bool SupressSimplerImplicitMoves) {
3598	// If this is the first return we've seen, infer the return type.
3599	// [expr.prim.lambda]p4 in C++11; block literals follow the same rules.
3600	CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(Val: getCurFunction());
3601	QualType FnRetType = CurCap->ReturnType;
3602	LambdaScopeInfo *CurLambda = dyn_cast<LambdaScopeInfo>(Val: CurCap);
3603	if (CurLambda && CurLambda->CallOperator->getType().isNull())
3604	return StmtError();
3605	bool HasDeducedReturnType =
3606	CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
3607
3608	if (ExprEvalContexts.back().isDiscardedStatementContext() &&
3609	(HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
3610	if (RetValExp) {
3611	ExprResult ER =
3612	ActOnFinishFullExpr(Expr: RetValExp, CC: ReturnLoc, /*DiscardedValue*/ false);
3613	if (ER.isInvalid())
3614	return StmtError();
3615	RetValExp = ER.get();
3616	}
3617	return ReturnStmt::Create(Ctx: Context, RL: ReturnLoc, E: RetValExp,
3618	/* NRVOCandidate=*/nullptr);
3619	}
3620
3621	if (HasDeducedReturnType) {
3622	FunctionDecl *FD = CurLambda->CallOperator;
3623	// If we've already decided this lambda is invalid, e.g. because
3624	// we saw a `return` whose expression had an error, don't keep
3625	// trying to deduce its return type.
3626	if (FD->isInvalidDecl())
3627	return StmtError();
3628	// In C++1y, the return type may involve 'auto'.
3629	// FIXME: Blocks might have a return type of 'auto' explicitly specified.
3630	if (CurCap->ReturnType.isNull())
3631	CurCap->ReturnType = FD->getReturnType();
3632
3633	AutoType *AT = CurCap->ReturnType->getContainedAutoType();
3634	assert(AT && "lost auto type from lambda return type");
3635	if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetExpr: RetValExp, AT)) {
3636	FD->setInvalidDecl();
3637	// FIXME: preserve the ill-formed return expression.
3638	return StmtError();
3639	}
3640	CurCap->ReturnType = FnRetType = FD->getReturnType();
3641	} else if (CurCap->HasImplicitReturnType) {
3642	// For blocks/lambdas with implicit return types, we check each return
3643	// statement individually, and deduce the common return type when the block
3644	// or lambda is completed.
3645	// FIXME: Fold this into the 'auto' codepath above.
3646	if (RetValExp && !isa<InitListExpr>(Val: RetValExp)) {
3647	ExprResult Result = DefaultFunctionArrayLvalueConversion(E: RetValExp);
3648	if (Result.isInvalid())
3649	return StmtError();
3650	RetValExp = Result.get();
3651
3652	// DR1048: even prior to C++14, we should use the 'auto' deduction rules
3653	// when deducing a return type for a lambda-expression (or by extension
3654	// for a block). These rules differ from the stated C++11 rules only in
3655	// that they remove top-level cv-qualifiers.
3656	if (!CurContext->isDependentContext())
3657	FnRetType = RetValExp->getType().getUnqualifiedType();
3658	else
3659	FnRetType = CurCap->ReturnType = Context.DependentTy;
3660	} else {
3661	if (RetValExp) {
3662	// C++11 [expr.lambda.prim]p4 bans inferring the result from an
3663	// initializer list, because it is not an expression (even
3664	// though we represent it as one). We still deduce 'void'.
3665	Diag(ReturnLoc, diag::err_lambda_return_init_list)
3666	<< RetValExp->getSourceRange();
3667	}
3668
3669	FnRetType = Context.VoidTy;
3670	}
3671
3672	// Although we'll properly infer the type of the block once it's completed,
3673	// make sure we provide a return type now for better error recovery.
3674	if (CurCap->ReturnType.isNull())
3675	CurCap->ReturnType = FnRetType;
3676	}
3677	const VarDecl *NRVOCandidate = getCopyElisionCandidate(Info&: NRInfo, ReturnType: FnRetType);
3678
3679	if (auto *CurBlock = dyn_cast<BlockScopeInfo>(Val: CurCap)) {
3680	if (CurBlock->FunctionType->castAs<FunctionType>()->getNoReturnAttr()) {
3681	Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr);
3682	return StmtError();
3683	}
3684	} else if (auto *CurRegion = dyn_cast<CapturedRegionScopeInfo>(Val: CurCap)) {
3685	Diag(ReturnLoc, diag::err_return_in_captured_stmt) << CurRegion->getRegionName();
3686	return StmtError();
3687	} else {
3688	assert(CurLambda && "unknown kind of captured scope");
3689	if (CurLambda->CallOperator->getType()
3690	->castAs<FunctionType>()
3691	->getNoReturnAttr()) {
3692	Diag(ReturnLoc, diag::err_noreturn_lambda_has_return_expr);
3693	return StmtError();
3694	}
3695	}
3696
3697	// Otherwise, verify that this result type matches the previous one. We are
3698	// pickier with blocks than for normal functions because we don't have GCC
3699	// compatibility to worry about here.
3700	if (FnRetType->isDependentType()) {
3701	// Delay processing for now. TODO: there are lots of dependent
3702	// types we can conclusively prove aren't void.
3703	} else if (FnRetType->isVoidType()) {
3704	if (RetValExp && !isa<InitListExpr>(Val: RetValExp) &&
3705	!(getLangOpts().CPlusPlus &&
3706	(RetValExp->isTypeDependent() ||
3707	RetValExp->getType()->isVoidType()))) {
3708	if (!getLangOpts().CPlusPlus &&
3709	RetValExp->getType()->isVoidType())
3710	Diag(ReturnLoc, diag::ext_return_has_void_expr) << "literal" << 2;
3711	else {
3712	Diag(ReturnLoc, diag::err_return_block_has_expr);
3713	RetValExp = nullptr;
3714	}
3715	}
3716	} else if (!RetValExp) {
3717	return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
3718	} else if (!RetValExp->isTypeDependent()) {
3719	// we have a non-void block with an expression, continue checking
3720
3721	// C99 6.8.6.4p3(136): The return statement is not an assignment. The
3722	// overlap restriction of subclause 6.5.16.1 does not apply to the case of
3723	// function return.
3724
3725	// In C++ the return statement is handled via a copy initialization.
3726	// the C version of which boils down to CheckSingleAssignmentConstraints.
3727	InitializedEntity Entity =
3728	InitializedEntity::InitializeResult(ReturnLoc, Type: FnRetType);
3729	ExprResult Res = PerformMoveOrCopyInitialization(
3730	Entity, NRInfo, Value: RetValExp, SupressSimplerImplicitMoves);
3731	if (Res.isInvalid()) {
3732	// FIXME: Cleanup temporaries here, anyway?
3733	return StmtError();
3734	}
3735	RetValExp = Res.get();
3736	CheckReturnValExpr(RetValExp, lhsType: FnRetType, ReturnLoc);
3737	}
3738
3739	if (RetValExp) {
3740	ExprResult ER =
3741	ActOnFinishFullExpr(Expr: RetValExp, CC: ReturnLoc, /*DiscardedValue*/ false);
3742	if (ER.isInvalid())
3743	return StmtError();
3744	RetValExp = ER.get();
3745	}
3746	auto *Result =
3747	ReturnStmt::Create(Ctx: Context, RL: ReturnLoc, E: RetValExp, NRVOCandidate);
3748
3749	// If we need to check for the named return value optimization,
3750	// or if we need to infer the return type,
3751	// save the return statement in our scope for later processing.
3752	if (CurCap->HasImplicitReturnType || NRVOCandidate)
3753	FunctionScopes.back()->Returns.push_back(Elt: Result);
3754
3755	if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3756	FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3757
3758	if (auto *CurBlock = dyn_cast<BlockScopeInfo>(Val: CurCap);
3759	CurBlock && CurCap->HasImplicitReturnType && RetValExp &&
3760	RetValExp->containsErrors())
3761	CurBlock->TheDecl->setInvalidDecl();
3762
3763	return Result;
3764	}
3765
3766	namespace {
3767	/// Marks all typedefs in all local classes in a type referenced.
3768	///
3769	/// In a function like
3770	/// auto f() {
3771	/// struct S { typedef int a; };
3772	/// return S();
3773	/// }
3774	///
3775	/// the local type escapes and could be referenced in some TUs but not in
3776	/// others. Pretend that all local typedefs are always referenced, to not warn
3777	/// on this. This isn't necessary if f has internal linkage, or the typedef
3778	/// is private.
3779	class LocalTypedefNameReferencer
3780	: public RecursiveASTVisitor<LocalTypedefNameReferencer> {
3781	public:
3782	LocalTypedefNameReferencer(Sema &S) : S(S) {}
3783	bool VisitRecordType(const RecordType *RT);
3784	private:
3785	Sema &S;
3786	};
3787	bool LocalTypedefNameReferencer::VisitRecordType(const RecordType *RT) {
3788	auto *R = dyn_cast<CXXRecordDecl>(Val: RT->getDecl());
3789	if (!R || !R->isLocalClass() || !R->isLocalClass()->isExternallyVisible() ||
3790	R->isDependentType())
3791	return true;
3792	for (auto *TmpD : R->decls())
3793	if (auto *T = dyn_cast<TypedefNameDecl>(TmpD))
3794	if (T->getAccess() != AS_private || R->hasFriends())
3795	S.MarkAnyDeclReferenced(T->getLocation(), T, /*OdrUse=*/false);
3796	return true;
3797	}
3798	}
3799
3800	TypeLoc Sema::getReturnTypeLoc(FunctionDecl *FD) const {
3801	return FD->getTypeSourceInfo()
3802	->getTypeLoc()
3803	.getAsAdjusted<FunctionProtoTypeLoc>()
3804	.getReturnLoc();
3805	}
3806
3807	/// Deduce the return type for a function from a returned expression, per
3808	/// C++1y [dcl.spec.auto]p6.
3809	bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
3810	SourceLocation ReturnLoc,
3811	Expr *RetExpr, const AutoType *AT) {
3812	// If this is the conversion function for a lambda, we choose to deduce its
3813	// type from the corresponding call operator, not from the synthesized return
3814	// statement within it. See Sema::DeduceReturnType.
3815	if (isLambdaConversionOperator(FD))
3816	return false;
3817
3818	if (RetExpr && isa<InitListExpr>(Val: RetExpr)) {
3819	// If the deduction is for a return statement and the initializer is
3820	// a braced-init-list, the program is ill-formed.
3821	Diag(RetExpr->getExprLoc(),
3822	getCurLambda() ? diag::err_lambda_return_init_list
3823	: diag::err_auto_fn_return_init_list)
3824	<< RetExpr->getSourceRange();
3825	return true;
3826	}
3827
3828	if (FD->isDependentContext()) {
3829	// C++1y [dcl.spec.auto]p12:
3830	// Return type deduction [...] occurs when the definition is
3831	// instantiated even if the function body contains a return
3832	// statement with a non-type-dependent operand.
3833	assert(AT->isDeduced() && "should have deduced to dependent type");
3834	return false;
3835	}
3836
3837	TypeLoc OrigResultType = getReturnTypeLoc(FD);
3838	// In the case of a return with no operand, the initializer is considered
3839	// to be void().
3840	CXXScalarValueInitExpr VoidVal(Context.VoidTy, nullptr, SourceLocation());
3841	if (!RetExpr) {
3842	// For a function with a deduced result type to return with omitted
3843	// expression, the result type as written must be 'auto' or
3844	// 'decltype(auto)', possibly cv-qualified or constrained, but not
3845	// ref-qualified.
3846	if (!OrigResultType.getType()->getAs<AutoType>()) {
3847	Diag(ReturnLoc, diag::err_auto_fn_return_void_but_not_auto)
3848	<< OrigResultType.getType();
3849	return true;
3850	}
3851	RetExpr = &VoidVal;
3852	}
3853
3854	QualType Deduced = AT->getDeducedType();
3855	{
3856	// Otherwise, [...] deduce a value for U using the rules of template
3857	// argument deduction.
3858	auto RetExprLoc = RetExpr->getExprLoc();
3859	TemplateDeductionInfo Info(RetExprLoc);
3860	SourceLocation TemplateSpecLoc;
3861	if (RetExpr->getType() == Context.OverloadTy) {
3862	auto FindResult = OverloadExpr::find(E: RetExpr);
3863	if (FindResult.Expression)
3864	TemplateSpecLoc = FindResult.Expression->getNameLoc();
3865	}
3866	TemplateSpecCandidateSet FailedTSC(TemplateSpecLoc);
3867	TemplateDeductionResult Res = DeduceAutoType(
3868	AutoTypeLoc: OrigResultType, Initializer: RetExpr, Result&: Deduced, Info, /*DependentDeduction=*/false,
3869	/*IgnoreConstraints=*/false, FailedTSC: &FailedTSC);
3870	if (Res != TemplateDeductionResult::Success && FD->isInvalidDecl())
3871	return true;
3872	switch (Res) {
3873	case TemplateDeductionResult::Success:
3874	break;
3875	case TemplateDeductionResult::AlreadyDiagnosed:
3876	return true;
3877	case TemplateDeductionResult::Inconsistent: {
3878	// If a function with a declared return type that contains a placeholder
3879	// type has multiple return statements, the return type is deduced for
3880	// each return statement. [...] if the type deduced is not the same in
3881	// each deduction, the program is ill-formed.
3882	const LambdaScopeInfo *LambdaSI = getCurLambda();
3883	if (LambdaSI && LambdaSI->HasImplicitReturnType)
3884	Diag(ReturnLoc, diag::err_typecheck_missing_return_type_incompatible)
3885	<< Info.SecondArg << Info.FirstArg << true /*IsLambda*/;
3886	else
3887	Diag(ReturnLoc, diag::err_auto_fn_different_deductions)
3888	<< (AT->isDecltypeAuto() ? 1 : 0) << Info.SecondArg
3889	<< Info.FirstArg;
3890	return true;
3891	}
3892	default:
3893	Diag(RetExpr->getExprLoc(), diag::err_auto_fn_deduction_failure)
3894	<< OrigResultType.getType() << RetExpr->getType();
3895	FailedTSC.NoteCandidates(S&: *this, Loc: RetExprLoc);
3896	return true;
3897	}
3898	}
3899
3900	// If a local type is part of the returned type, mark its fields as
3901	// referenced.
3902	LocalTypedefNameReferencer(*this).TraverseType(T: RetExpr->getType());
3903
3904	// CUDA: Kernel function must have 'void' return type.
3905	if (getLangOpts().CUDA && FD->hasAttr<CUDAGlobalAttr>() &&
3906	!Deduced->isVoidType()) {
3907	Diag(FD->getLocation(), diag::err_kern_type_not_void_return)
3908	<< FD->getType() << FD->getSourceRange();
3909	return true;
3910	}
3911
3912	if (!FD->isInvalidDecl() && AT->getDeducedType() != Deduced)
3913	// Update all declarations of the function to have the deduced return type.
3914	Context.adjustDeducedFunctionResultType(FD, ResultType: Deduced);
3915
3916	return false;
3917	}
3918
3919	StmtResult
3920	Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
3921	Scope *CurScope) {
3922	// Correct typos, in case the containing function returns 'auto' and
3923	// RetValExp should determine the deduced type.
3924	ExprResult RetVal = CorrectDelayedTyposInExpr(
3925	E: RetValExp, InitDecl: nullptr, /*RecoverUncorrectedTypos=*/true);
3926	if (RetVal.isInvalid())
3927	return StmtError();
3928	StmtResult R =
3929	BuildReturnStmt(ReturnLoc, RetValExp: RetVal.get(), /*AllowRecovery=*/true);
3930	if (R.isInvalid() || ExprEvalContexts.back().isDiscardedStatementContext())
3931	return R;
3932
3933	VarDecl *VD =
3934	const_cast<VarDecl *>(cast<ReturnStmt>(Val: R.get())->getNRVOCandidate());
3935
3936	CurScope->updateNRVOCandidate(VD);
3937
3938	CheckJumpOutOfSEHFinally(S&: *this, Loc: ReturnLoc, DestScope: *CurScope->getFnParent());
3939
3940	return R;
3941	}
3942
3943	static bool CheckSimplerImplicitMovesMSVCWorkaround(const Sema &S,
3944	const Expr *E) {
3945	if (!E || !S.getLangOpts().CPlusPlus23 || !S.getLangOpts().MSVCCompat)
3946	return false;
3947	const Decl *D = E->getReferencedDeclOfCallee();
3948	if (!D || !S.SourceMgr.isInSystemHeader(Loc: D->getLocation()))
3949	return false;
3950	for (const DeclContext *DC = D->getDeclContext(); DC; DC = DC->getParent()) {
3951	if (DC->isStdNamespace())
3952	return true;
3953	}
3954	return false;
3955	}
3956
3957	StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
3958	bool AllowRecovery) {
3959	// Check for unexpanded parameter packs.
3960	if (RetValExp && DiagnoseUnexpandedParameterPack(E: RetValExp))
3961	return StmtError();
3962
3963	// HACK: We suppress simpler implicit move here in msvc compatibility mode
3964	// just as a temporary work around, as the MSVC STL has issues with
3965	// this change.
3966	bool SupressSimplerImplicitMoves =
3967	CheckSimplerImplicitMovesMSVCWorkaround(S: *this, E: RetValExp);
3968	NamedReturnInfo NRInfo = getNamedReturnInfo(
3969	E&: RetValExp, Mode: SupressSimplerImplicitMoves ? SimplerImplicitMoveMode::ForceOff
3970	: SimplerImplicitMoveMode::Normal);
3971
3972	if (isa<CapturingScopeInfo>(Val: getCurFunction()))
3973	return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp, NRInfo,
3974	SupressSimplerImplicitMoves);
3975
3976	QualType FnRetType;
3977	QualType RelatedRetType;
3978	const AttrVec *Attrs = nullptr;
3979	bool isObjCMethod = false;
3980
3981	if (const FunctionDecl *FD = getCurFunctionDecl()) {
3982	FnRetType = FD->getReturnType();
3983	if (FD->hasAttrs())
3984	Attrs = &FD->getAttrs();
3985	if (FD->isNoReturn())
3986	Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr) << FD;
3987	if (FD->isMain() && RetValExp)
3988	if (isa<CXXBoolLiteralExpr>(RetValExp))
3989	Diag(ReturnLoc, diag::warn_main_returns_bool_literal)
3990	<< RetValExp->getSourceRange();
3991	if (FD->hasAttr<CmseNSEntryAttr>() && RetValExp) {
3992	if (const auto *RT = dyn_cast<RecordType>(Val: FnRetType.getCanonicalType())) {
3993	if (RT->getDecl()->isOrContainsUnion())
3994	Diag(RetValExp->getBeginLoc(), diag::warn_cmse_nonsecure_union) << 1;
3995	}
3996	}
3997	} else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
3998	FnRetType = MD->getReturnType();
3999	isObjCMethod = true;
4000	if (MD->hasAttrs())
4001	Attrs = &MD->getAttrs();
4002	if (MD->hasRelatedResultType() && MD->getClassInterface()) {
4003	// In the implementation of a method with a related return type, the
4004	// type used to type-check the validity of return statements within the
4005	// method body is a pointer to the type of the class being implemented.
4006	RelatedRetType = Context.getObjCInterfaceType(Decl: MD->getClassInterface());
4007	RelatedRetType = Context.getObjCObjectPointerType(OIT: RelatedRetType);
4008	}
4009	} else // If we don't have a function/method context, bail.
4010	return StmtError();
4011
4012	if (RetValExp) {
4013	const auto *ATy = dyn_cast<ArrayType>(Val: RetValExp->getType());
4014	if (ATy && ATy->getElementType().isWebAssemblyReferenceType()) {
4015	Diag(ReturnLoc, diag::err_wasm_table_art) << 1;
4016	return StmtError();
4017	}
4018	}
4019
4020	// C++1z: discarded return statements are not considered when deducing a
4021	// return type.
4022	if (ExprEvalContexts.back().isDiscardedStatementContext() &&
4023	FnRetType->getContainedAutoType()) {
4024	if (RetValExp) {
4025	ExprResult ER =
4026	ActOnFinishFullExpr(Expr: RetValExp, CC: ReturnLoc, /*DiscardedValue*/ false);
4027	if (ER.isInvalid())
4028	return StmtError();
4029	RetValExp = ER.get();
4030	}
4031	return ReturnStmt::Create(Ctx: Context, RL: ReturnLoc, E: RetValExp,
4032	/* NRVOCandidate=*/nullptr);
4033	}
4034
4035	// FIXME: Add a flag to the ScopeInfo to indicate whether we're performing
4036	// deduction.
4037	if (getLangOpts().CPlusPlus14) {
4038	if (AutoType *AT = FnRetType->getContainedAutoType()) {
4039	FunctionDecl *FD = cast<FunctionDecl>(Val: CurContext);
4040	// If we've already decided this function is invalid, e.g. because
4041	// we saw a `return` whose expression had an error, don't keep
4042	// trying to deduce its return type.
4043	// (Some return values may be needlessly wrapped in RecoveryExpr).
4044	if (FD->isInvalidDecl() ||
4045	DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetExpr: RetValExp, AT)) {
4046	FD->setInvalidDecl();
4047	if (!AllowRecovery)
4048	return StmtError();
4049	// The deduction failure is diagnosed and marked, try to recover.
4050	if (RetValExp) {
4051	// Wrap return value with a recovery expression of the previous type.
4052	// If no deduction yet, use DependentTy.
4053	auto Recovery = CreateRecoveryExpr(
4054	Begin: RetValExp->getBeginLoc(), End: RetValExp->getEndLoc(), SubExprs: RetValExp,
4055	T: AT->isDeduced() ? FnRetType : QualType());
4056	if (Recovery.isInvalid())
4057	return StmtError();
4058	RetValExp = Recovery.get();
4059	} else {
4060	// Nothing to do: a ReturnStmt with no value is fine recovery.
4061	}
4062	} else {
4063	FnRetType = FD->getReturnType();
4064	}
4065	}
4066	}
4067	const VarDecl *NRVOCandidate = getCopyElisionCandidate(Info&: NRInfo, ReturnType: FnRetType);
4068
4069	bool HasDependentReturnType = FnRetType->isDependentType();
4070
4071	ReturnStmt *Result = nullptr;
4072	if (FnRetType->isVoidType()) {
4073	if (RetValExp) {
4074	if (auto *ILE = dyn_cast<InitListExpr>(Val: RetValExp)) {
4075	// We simply never allow init lists as the return value of void
4076	// functions. This is compatible because this was never allowed before,
4077	// so there's no legacy code to deal with.
4078	NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4079	int FunctionKind = 0;
4080	if (isa<ObjCMethodDecl>(Val: CurDecl))
4081	FunctionKind = 1;
4082	else if (isa<CXXConstructorDecl>(Val: CurDecl))
4083	FunctionKind = 2;
4084	else if (isa<CXXDestructorDecl>(Val: CurDecl))
4085	FunctionKind = 3;
4086
4087	Diag(ReturnLoc, diag::err_return_init_list)
4088	<< CurDecl << FunctionKind << RetValExp->getSourceRange();
4089
4090	// Preserve the initializers in the AST.
4091	RetValExp = AllowRecovery
4092	? CreateRecoveryExpr(Begin: ILE->getLBraceLoc(),
4093	End: ILE->getRBraceLoc(), SubExprs: ILE->inits())
4094	.get()
4095	: nullptr;
4096	} else if (!RetValExp->isTypeDependent()) {
4097	// C99 6.8.6.4p1 (ext_ since GCC warns)
4098	unsigned D = diag::ext_return_has_expr;
4099	if (RetValExp->getType()->isVoidType()) {
4100	NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4101	if (isa<CXXConstructorDecl>(CurDecl) ||
4102	isa<CXXDestructorDecl>(CurDecl))
4103	D = diag::err_ctor_dtor_returns_void;
4104	else
4105	D = diag::ext_return_has_void_expr;
4106	}
4107	else {
4108	ExprResult Result = RetValExp;
4109	Result = IgnoredValueConversions(E: Result.get());
4110	if (Result.isInvalid())
4111	return StmtError();
4112	RetValExp = Result.get();
4113	RetValExp = ImpCastExprToType(E: RetValExp,
4114	Type: Context.VoidTy, CK: CK_ToVoid).get();
4115	}
4116	// return of void in constructor/destructor is illegal in C++.
4117	if (D == diag::err_ctor_dtor_returns_void) {
4118	NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4119	Diag(Loc: ReturnLoc, DiagID: D) << CurDecl << isa<CXXDestructorDecl>(Val: CurDecl)
4120	<< RetValExp->getSourceRange();
4121	}
4122	// return (some void expression); is legal in C++.
4123	else if (D != diag::ext_return_has_void_expr ||
4124	!getLangOpts().CPlusPlus) {
4125	NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4126
4127	int FunctionKind = 0;
4128	if (isa<ObjCMethodDecl>(Val: CurDecl))
4129	FunctionKind = 1;
4130	else if (isa<CXXConstructorDecl>(Val: CurDecl))
4131	FunctionKind = 2;
4132	else if (isa<CXXDestructorDecl>(Val: CurDecl))
4133	FunctionKind = 3;
4134
4135	Diag(Loc: ReturnLoc, DiagID: D)
4136	<< CurDecl << FunctionKind << RetValExp->getSourceRange();
4137	}
4138	}
4139
4140	if (RetValExp) {
4141	ExprResult ER =
4142	ActOnFinishFullExpr(Expr: RetValExp, CC: ReturnLoc, /*DiscardedValue*/ false);
4143	if (ER.isInvalid())
4144	return StmtError();
4145	RetValExp = ER.get();
4146	}
4147	}
4148
4149	Result = ReturnStmt::Create(Ctx: Context, RL: ReturnLoc, E: RetValExp,
4150	/* NRVOCandidate=*/nullptr);
4151	} else if (!RetValExp && !HasDependentReturnType) {
4152	FunctionDecl *FD = getCurFunctionDecl();
4153
4154	if ((FD && FD->isInvalidDecl()) || FnRetType->containsErrors()) {
4155	// The intended return type might have been "void", so don't warn.
4156	} else if (getLangOpts().CPlusPlus11 && FD && FD->isConstexpr()) {
4157	// C++11 [stmt.return]p2
4158	Diag(ReturnLoc, diag::err_constexpr_return_missing_expr)
4159	<< FD << FD->isConsteval();
4160	FD->setInvalidDecl();
4161	} else {
4162	// C99 6.8.6.4p1 (ext_ since GCC warns)
4163	// C90 6.6.6.4p4
4164	unsigned DiagID = getLangOpts().C99 ? diag::ext_return_missing_expr
4165	: diag::warn_return_missing_expr;
4166	// Note that at this point one of getCurFunctionDecl() or
4167	// getCurMethodDecl() must be non-null (see above).
4168	assert((getCurFunctionDecl() || getCurMethodDecl()) &&
4169	"Not in a FunctionDecl or ObjCMethodDecl?");
4170	bool IsMethod = FD == nullptr;
4171	const NamedDecl *ND =
4172	IsMethod ? cast<NamedDecl>(Val: getCurMethodDecl()) : cast<NamedDecl>(Val: FD);
4173	Diag(Loc: ReturnLoc, DiagID) << ND << IsMethod;
4174	}
4175
4176	Result = ReturnStmt::Create(Ctx: Context, RL: ReturnLoc, /* RetExpr=*/E: nullptr,
4177	/* NRVOCandidate=*/nullptr);
4178	} else {
4179	assert(RetValExp || HasDependentReturnType);
4180	QualType RetType = RelatedRetType.isNull() ? FnRetType : RelatedRetType;
4181
4182	// C99 6.8.6.4p3(136): The return statement is not an assignment. The
4183	// overlap restriction of subclause 6.5.16.1 does not apply to the case of
4184	// function return.
4185
4186	// In C++ the return statement is handled via a copy initialization,
4187	// the C version of which boils down to CheckSingleAssignmentConstraints.
4188	if (!HasDependentReturnType && !RetValExp->isTypeDependent()) {
4189	// we have a non-void function with an expression, continue checking
4190	InitializedEntity Entity =
4191	InitializedEntity::InitializeResult(ReturnLoc, Type: RetType);
4192	ExprResult Res = PerformMoveOrCopyInitialization(
4193	Entity, NRInfo, Value: RetValExp, SupressSimplerImplicitMoves);
4194	if (Res.isInvalid() && AllowRecovery)
4195	Res = CreateRecoveryExpr(Begin: RetValExp->getBeginLoc(),
4196	End: RetValExp->getEndLoc(), SubExprs: RetValExp, T: RetType);
4197	if (Res.isInvalid()) {
4198	// FIXME: Clean up temporaries here anyway?
4199	return StmtError();
4200	}
4201	RetValExp = Res.getAs<Expr>();
4202
4203	// If we have a related result type, we need to implicitly
4204	// convert back to the formal result type. We can't pretend to
4205	// initialize the result again --- we might end double-retaining
4206	// --- so instead we initialize a notional temporary.
4207	if (!RelatedRetType.isNull()) {
4208	Entity = InitializedEntity::InitializeRelatedResult(MD: getCurMethodDecl(),
4209	Type: FnRetType);
4210	Res = PerformCopyInitialization(Entity, EqualLoc: ReturnLoc, Init: RetValExp);
4211	if (Res.isInvalid()) {
4212	// FIXME: Clean up temporaries here anyway?
4213	return StmtError();
4214	}
4215	RetValExp = Res.getAs<Expr>();
4216	}
4217
4218	CheckReturnValExpr(RetValExp, lhsType: FnRetType, ReturnLoc, isObjCMethod, Attrs,
4219	FD: getCurFunctionDecl());
4220	}
4221
4222	if (RetValExp) {
4223	ExprResult ER =
4224	ActOnFinishFullExpr(Expr: RetValExp, CC: ReturnLoc, /*DiscardedValue*/ false);
4225	if (ER.isInvalid())
4226	return StmtError();
4227	RetValExp = ER.get();
4228	}
4229	Result = ReturnStmt::Create(Ctx: Context, RL: ReturnLoc, E: RetValExp, NRVOCandidate);
4230	}
4231
4232	// If we need to check for the named return value optimization, save the
4233	// return statement in our scope for later processing.
4234	if (Result->getNRVOCandidate())
4235	FunctionScopes.back()->Returns.push_back(Elt: Result);
4236
4237	if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
4238	FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
4239
4240	return Result;
4241	}
4242
4243	StmtResult
4244	Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
4245	SourceLocation RParen, Decl *Parm,
4246	Stmt *Body) {
4247	VarDecl *Var = cast_or_null<VarDecl>(Val: Parm);
4248	if (Var && Var->isInvalidDecl())
4249	return StmtError();
4250
4251	return new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body);
4252	}
4253
4254	StmtResult
4255	Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
4256	return new (Context) ObjCAtFinallyStmt(AtLoc, Body);
4257	}
4258
4259	StmtResult
4260	Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
4261	MultiStmtArg CatchStmts, Stmt *Finally) {
4262	if (!getLangOpts().ObjCExceptions)
4263	Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@try";
4264
4265	// Objective-C try is incompatible with SEH __try.
4266	sema::FunctionScopeInfo *FSI = getCurFunction();
4267	if (FSI->FirstSEHTryLoc.isValid()) {
4268	Diag(AtLoc, diag::err_mixing_cxx_try_seh_try) << 1;
4269	Diag(FSI->FirstSEHTryLoc, diag::note_conflicting_try_here) << "'__try'";
4270	}
4271
4272	FSI->setHasObjCTry(AtLoc);
4273	unsigned NumCatchStmts = CatchStmts.size();
4274	return ObjCAtTryStmt::Create(Context, atTryLoc: AtLoc, atTryStmt: Try, CatchStmts: CatchStmts.data(),
4275	NumCatchStmts, atFinallyStmt: Finally);
4276	}
4277
4278	StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) {
4279	if (Throw) {
4280	ExprResult Result = DefaultLvalueConversion(E: Throw);
4281	if (Result.isInvalid())
4282	return StmtError();
4283
4284	Result = ActOnFinishFullExpr(Expr: Result.get(), /*DiscardedValue*/ false);
4285	if (Result.isInvalid())
4286	return StmtError();
4287	Throw = Result.get();
4288
4289	QualType ThrowType = Throw->getType();
4290	// Make sure the expression type is an ObjC pointer or "void *".
4291	if (!ThrowType->isDependentType() &&
4292	!ThrowType->isObjCObjectPointerType()) {
4293	const PointerType *PT = ThrowType->getAs<PointerType>();
4294	if (!PT || !PT->getPointeeType()->isVoidType())
4295	return StmtError(Diag(AtLoc, diag::err_objc_throw_expects_object)
4296	<< Throw->getType() << Throw->getSourceRange());
4297	}
4298	}
4299
4300	return new (Context) ObjCAtThrowStmt(AtLoc, Throw);
4301	}
4302
4303	StmtResult
4304	Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
4305	Scope *CurScope) {
4306	if (!getLangOpts().ObjCExceptions)
4307	Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@throw";
4308
4309	if (!Throw) {
4310	// @throw without an expression designates a rethrow (which must occur
4311	// in the context of an @catch clause).
4312	Scope *AtCatchParent = CurScope;
4313	while (AtCatchParent && !AtCatchParent->isAtCatchScope())
4314	AtCatchParent = AtCatchParent->getParent();
4315	if (!AtCatchParent)
4316	return StmtError(Diag(AtLoc, diag::err_rethrow_used_outside_catch));
4317	}
4318	return BuildObjCAtThrowStmt(AtLoc, Throw);
4319	}
4320
4321	ExprResult
4322	Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
4323	ExprResult result = DefaultLvalueConversion(E: operand);
4324	if (result.isInvalid())
4325	return ExprError();
4326	operand = result.get();
4327
4328	// Make sure the expression type is an ObjC pointer or "void *".
4329	QualType type = operand->getType();
4330	if (!type->isDependentType() &&
4331	!type->isObjCObjectPointerType()) {
4332	const PointerType *pointerType = type->getAs<PointerType>();
4333	if (!pointerType || !pointerType->getPointeeType()->isVoidType()) {
4334	if (getLangOpts().CPlusPlus) {
4335	if (RequireCompleteType(atLoc, type,
4336	diag::err_incomplete_receiver_type))
4337	return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4338	<< type << operand->getSourceRange();
4339
4340	ExprResult result = PerformContextuallyConvertToObjCPointer(From: operand);
4341	if (result.isInvalid())
4342	return ExprError();
4343	if (!result.isUsable())
4344	return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4345	<< type << operand->getSourceRange();
4346
4347	operand = result.get();
4348	} else {
4349	return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4350	<< type << operand->getSourceRange();
4351	}
4352	}
4353	}
4354
4355	// The operand to @synchronized is a full-expression.
4356	return ActOnFinishFullExpr(Expr: operand, /*DiscardedValue*/ false);
4357	}
4358
4359	StmtResult
4360	Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
4361	Stmt *SyncBody) {
4362	// We can't jump into or indirect-jump out of a @synchronized block.
4363	setFunctionHasBranchProtectedScope();
4364	return new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody);
4365	}
4366
4367	/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
4368	/// and creates a proper catch handler from them.
4369	StmtResult
4370	Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
4371	Stmt *HandlerBlock) {
4372	// There's nothing to test that ActOnExceptionDecl didn't already test.
4373	return new (Context)
4374	CXXCatchStmt(CatchLoc, cast_or_null<VarDecl>(Val: ExDecl), HandlerBlock);
4375	}
4376
4377	StmtResult
4378	Sema::ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body) {
4379	setFunctionHasBranchProtectedScope();
4380	return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body);
4381	}
4382
4383	namespace {
4384	class CatchHandlerType {
4385	QualType QT;
4386	LLVM_PREFERRED_TYPE(bool)
4387	unsigned IsPointer : 1;
4388
4389	// This is a special constructor to be used only with DenseMapInfo's
4390	// getEmptyKey() and getTombstoneKey() functions.
4391	friend struct llvm::DenseMapInfo<CatchHandlerType>;
4392	enum Unique { ForDenseMap };
4393	CatchHandlerType(QualType QT, Unique) : QT(QT), IsPointer(false) {}
4394
4395	public:
4396	/// Used when creating a CatchHandlerType from a handler type; will determine
4397	/// whether the type is a pointer or reference and will strip off the top
4398	/// level pointer and cv-qualifiers.
4399	CatchHandlerType(QualType Q) : QT(Q), IsPointer(false) {
4400	if (QT->isPointerType())
4401	IsPointer = true;
4402
4403	QT = QT.getUnqualifiedType();
4404	if (IsPointer || QT->isReferenceType())
4405	QT = QT->getPointeeType();
4406	}
4407
4408	/// Used when creating a CatchHandlerType from a base class type; pretends the
4409	/// type passed in had the pointer qualifier, does not need to get an
4410	/// unqualified type.
4411	CatchHandlerType(QualType QT, bool IsPointer)
4412	: QT(QT), IsPointer(IsPointer) {}
4413
4414	QualType underlying() const { return QT; }
4415	bool isPointer() const { return IsPointer; }
4416
4417	friend bool operator==(const CatchHandlerType &LHS,
4418	const CatchHandlerType &RHS) {
4419	// If the pointer qualification does not match, we can return early.
4420	if (LHS.IsPointer != RHS.IsPointer)
4421	return false;
4422	// Otherwise, check the underlying type without cv-qualifiers.
4423	return LHS.QT == RHS.QT;
4424	}
4425	};
4426	} // namespace
4427
4428	namespace llvm {
4429	template <> struct DenseMapInfo<CatchHandlerType> {
4430	static CatchHandlerType getEmptyKey() {
4431	return CatchHandlerType(DenseMapInfo<QualType>::getEmptyKey(),
4432	CatchHandlerType::ForDenseMap);
4433	}
4434
4435	static CatchHandlerType getTombstoneKey() {
4436	return CatchHandlerType(DenseMapInfo<QualType>::getTombstoneKey(),
4437	CatchHandlerType::ForDenseMap);
4438	}
4439
4440	static unsigned getHashValue(const CatchHandlerType &Base) {
4441	return DenseMapInfo<QualType>::getHashValue(Val: Base.underlying());
4442	}
4443
4444	static bool isEqual(const CatchHandlerType &LHS,
4445	const CatchHandlerType &RHS) {
4446	return LHS == RHS;
4447	}
4448	};
4449	}
4450
4451	namespace {
4452	class CatchTypePublicBases {
4453	const llvm::DenseMap<QualType, CXXCatchStmt *> &TypesToCheck;
4454
4455	CXXCatchStmt *FoundHandler;
4456	QualType FoundHandlerType;
4457	QualType TestAgainstType;
4458
4459	public:
4460	CatchTypePublicBases(const llvm::DenseMap<QualType, CXXCatchStmt *> &T,
4461	QualType QT)
4462	: TypesToCheck(T), FoundHandler(nullptr), TestAgainstType(QT) {}
4463
4464	CXXCatchStmt *getFoundHandler() const { return FoundHandler; }
4465	QualType getFoundHandlerType() const { return FoundHandlerType; }
4466
4467	bool operator()(const CXXBaseSpecifier *S, CXXBasePath &) {
4468	if (S->getAccessSpecifier() == AccessSpecifier::AS_public) {
4469	QualType Check = S->getType().getCanonicalType();
4470	const auto &M = TypesToCheck;
4471	auto I = M.find(Val: Check);
4472	if (I != M.end()) {
4473	// We're pretty sure we found what we need to find. However, we still
4474	// need to make sure that we properly compare for pointers and
4475	// references, to handle cases like:
4476	//
4477	// } catch (Base *b) {
4478	// } catch (Derived &d) {
4479	// }
4480	//
4481	// where there is a qualification mismatch that disqualifies this
4482	// handler as a potential problem.
4483	if (I->second->getCaughtType()->isPointerType() ==
4484	TestAgainstType->isPointerType()) {
4485	FoundHandler = I->second;
4486	FoundHandlerType = Check;
4487	return true;
4488	}
4489	}
4490	}
4491	return false;
4492	}
4493	};
4494	}
4495
4496	/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
4497	/// handlers and creates a try statement from them.
4498	StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
4499	ArrayRef<Stmt *> Handlers) {
4500	const llvm::Triple &T = Context.getTargetInfo().getTriple();
4501	const bool IsOpenMPGPUTarget =
4502	getLangOpts().OpenMPIsTargetDevice && (T.isNVPTX() || T.isAMDGCN());
4503	// Don't report an error if 'try' is used in system headers or in an OpenMP
4504	// target region compiled for a GPU architecture.
4505	if (!IsOpenMPGPUTarget && !getLangOpts().CXXExceptions &&
4506	!getSourceManager().isInSystemHeader(Loc: TryLoc) && !getLangOpts().CUDA) {
4507	// Delay error emission for the OpenMP device code.
4508	targetDiag(TryLoc, diag::err_exceptions_disabled) << "try";
4509	}
4510
4511	// In OpenMP target regions, we assume that catch is never reached on GPU
4512	// targets.
4513	if (IsOpenMPGPUTarget)
4514	targetDiag(TryLoc, diag::warn_try_not_valid_on_target) << T.str();
4515
4516	// Exceptions aren't allowed in CUDA device code.
4517	if (getLangOpts().CUDA)
4518	CUDADiagIfDeviceCode(TryLoc, diag::err_cuda_device_exceptions)
4519	<< "try" << CurrentCUDATarget();
4520
4521	if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope())
4522	Diag(TryLoc, diag::err_omp_simd_region_cannot_use_stmt) << "try";
4523
4524	sema::FunctionScopeInfo *FSI = getCurFunction();
4525
4526	// C++ try is incompatible with SEH __try.
4527	if (!getLangOpts().Borland && FSI->FirstSEHTryLoc.isValid()) {
4528	Diag(TryLoc, diag::err_mixing_cxx_try_seh_try) << 0;
4529	Diag(FSI->FirstSEHTryLoc, diag::note_conflicting_try_here) << "'__try'";
4530	}
4531
4532	const unsigned NumHandlers = Handlers.size();
4533	assert(!Handlers.empty() &&
4534	"The parser shouldn't call this if there are no handlers.");
4535
4536	llvm::DenseMap<QualType, CXXCatchStmt *> HandledBaseTypes;
4537	llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> HandledTypes;
4538	for (unsigned i = 0; i < NumHandlers; ++i) {
4539	CXXCatchStmt *H = cast<CXXCatchStmt>(Val: Handlers[i]);
4540
4541	// Diagnose when the handler is a catch-all handler, but it isn't the last
4542	// handler for the try block. [except.handle]p5. Also, skip exception
4543	// declarations that are invalid, since we can't usefully report on them.
4544	if (!H->getExceptionDecl()) {
4545	if (i < NumHandlers - 1)
4546	return StmtError(Diag(H->getBeginLoc(), diag::err_early_catch_all));
4547	continue;
4548	} else if (H->getExceptionDecl()->isInvalidDecl())
4549	continue;
4550
4551	// Walk the type hierarchy to diagnose when this type has already been
4552	// handled (duplication), or cannot be handled (derivation inversion). We
4553	// ignore top-level cv-qualifiers, per [except.handle]p3
4554	CatchHandlerType HandlerCHT = H->getCaughtType().getCanonicalType();
4555
4556	// We can ignore whether the type is a reference or a pointer; we need the
4557	// underlying declaration type in order to get at the underlying record
4558	// decl, if there is one.
4559	QualType Underlying = HandlerCHT.underlying();
4560	if (auto *RD = Underlying->getAsCXXRecordDecl()) {
4561	if (!RD->hasDefinition())
4562	continue;
4563	// Check that none of the public, unambiguous base classes are in the
4564	// map ([except.handle]p1). Give the base classes the same pointer
4565	// qualification as the original type we are basing off of. This allows
4566	// comparison against the handler type using the same top-level pointer
4567	// as the original type.
4568	CXXBasePaths Paths;
4569	Paths.setOrigin(RD);
4570	CatchTypePublicBases CTPB(HandledBaseTypes,
4571	H->getCaughtType().getCanonicalType());
4572	if (RD->lookupInBases(BaseMatches: CTPB, Paths)) {
4573	const CXXCatchStmt *Problem = CTPB.getFoundHandler();
4574	if (!Paths.isAmbiguous(
4575	BaseType: CanQualType::CreateUnsafe(Other: CTPB.getFoundHandlerType()))) {
4576	Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
4577	diag::warn_exception_caught_by_earlier_handler)
4578	<< H->getCaughtType();
4579	Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
4580	diag::note_previous_exception_handler)
4581	<< Problem->getCaughtType();
4582	}
4583	}
4584	// Strip the qualifiers here because we're going to be comparing this
4585	// type to the base type specifiers of a class, which are ignored in a
4586	// base specifier per [class.derived.general]p2.
4587	HandledBaseTypes[Underlying.getUnqualifiedType()] = H;
4588	}
4589
4590	// Add the type the list of ones we have handled; diagnose if we've already
4591	// handled it.
4592	auto R = HandledTypes.insert(
4593	std::make_pair(x: H->getCaughtType().getCanonicalType(), y&: H));
4594	if (!R.second) {
4595	const CXXCatchStmt *Problem = R.first->second;
4596	Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
4597	diag::warn_exception_caught_by_earlier_handler)
4598	<< H->getCaughtType();
4599	Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
4600	diag::note_previous_exception_handler)
4601	<< Problem->getCaughtType();
4602	}
4603	}
4604
4605	FSI->setHasCXXTry(TryLoc);
4606
4607	return CXXTryStmt::Create(C: Context, tryLoc: TryLoc, tryBlock: cast<CompoundStmt>(Val: TryBlock),
4608	handlers: Handlers);
4609	}
4610
4611	StmtResult Sema::ActOnSEHTryBlock(bool IsCXXTry, SourceLocation TryLoc,
4612	Stmt *TryBlock, Stmt *Handler) {
4613	assert(TryBlock && Handler);
4614
4615	sema::FunctionScopeInfo *FSI = getCurFunction();
4616
4617	// SEH __try is incompatible with C++ try. Borland appears to support this,
4618	// however.
4619	if (!getLangOpts().Borland) {
4620	if (FSI->FirstCXXOrObjCTryLoc.isValid()) {
4621	Diag(TryLoc, diag::err_mixing_cxx_try_seh_try) << FSI->FirstTryType;
4622	Diag(FSI->FirstCXXOrObjCTryLoc, diag::note_conflicting_try_here)
4623	<< (FSI->FirstTryType == sema::FunctionScopeInfo::TryLocIsCXX
4624	? "'try'"
4625	: "'@try'");
4626	}
4627	}
4628
4629	FSI->setHasSEHTry(TryLoc);
4630
4631	// Reject __try in Obj-C methods, blocks, and captured decls, since we don't
4632	// track if they use SEH.
4633	DeclContext *DC = CurContext;
4634	while (DC && !DC->isFunctionOrMethod())
4635	DC = DC->getParent();
4636	FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(Val: DC);
4637	if (FD)
4638	FD->setUsesSEHTry(true);
4639	else
4640	Diag(TryLoc, diag::err_seh_try_outside_functions);
4641
4642	// Reject __try on unsupported targets.
4643	if (!Context.getTargetInfo().isSEHTrySupported())
4644	Diag(TryLoc, diag::err_seh_try_unsupported);
4645
4646	return SEHTryStmt::Create(C: Context, isCXXTry: IsCXXTry, TryLoc, TryBlock, Handler);
4647	}
4648
4649	StmtResult Sema::ActOnSEHExceptBlock(SourceLocation Loc, Expr *FilterExpr,
4650	Stmt *Block) {
4651	assert(FilterExpr && Block);
4652	QualType FTy = FilterExpr->getType();
4653	if (!FTy->isIntegerType() && !FTy->isDependentType()) {
4654	return StmtError(
4655	Diag(FilterExpr->getExprLoc(), diag::err_filter_expression_integral)
4656	<< FTy);
4657	}
4658	return SEHExceptStmt::Create(C: Context, ExceptLoc: Loc, FilterExpr, Block);
4659	}
4660
4661	void Sema::ActOnStartSEHFinallyBlock() {
4662	CurrentSEHFinally.push_back(Elt: CurScope);
4663	}
4664
4665	void Sema::ActOnAbortSEHFinallyBlock() {
4666	CurrentSEHFinally.pop_back();
4667	}
4668
4669	StmtResult Sema::ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block) {
4670	assert(Block);
4671	CurrentSEHFinally.pop_back();
4672	return SEHFinallyStmt::Create(C: Context, FinallyLoc: Loc, Block);
4673	}
4674
4675	StmtResult
4676	Sema::ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope) {
4677	Scope *SEHTryParent = CurScope;
4678	while (SEHTryParent && !SEHTryParent->isSEHTryScope())
4679	SEHTryParent = SEHTryParent->getParent();
4680	if (!SEHTryParent)
4681	return StmtError(Diag(Loc, diag::err_ms___leave_not_in___try));
4682	CheckJumpOutOfSEHFinally(S&: *this, Loc, DestScope: *SEHTryParent);
4683
4684	return new (Context) SEHLeaveStmt(Loc);
4685	}
4686
4687	StmtResult Sema::BuildMSDependentExistsStmt(SourceLocation KeywordLoc,
4688	bool IsIfExists,
4689	NestedNameSpecifierLoc QualifierLoc,
4690	DeclarationNameInfo NameInfo,
4691	Stmt *Nested)
4692	{
4693	return new (Context) MSDependentExistsStmt(KeywordLoc, IsIfExists,
4694	QualifierLoc, NameInfo,
4695	cast<CompoundStmt>(Val: Nested));
4696	}
4697
4698
4699	StmtResult Sema::ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,
4700	bool IsIfExists,
4701	CXXScopeSpec &SS,
4702	UnqualifiedId &Name,
4703	Stmt *Nested) {
4704	return BuildMSDependentExistsStmt(KeywordLoc, IsIfExists,
4705	QualifierLoc: SS.getWithLocInContext(Context),
4706	NameInfo: GetNameFromUnqualifiedId(Name),
4707	Nested);
4708	}
4709
4710	RecordDecl*
4711	Sema::CreateCapturedStmtRecordDecl(CapturedDecl *&CD, SourceLocation Loc,
4712	unsigned NumParams) {
4713	DeclContext *DC = CurContext;
4714	while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
4715	DC = DC->getParent();
4716
4717	RecordDecl *RD = nullptr;
4718	if (getLangOpts().CPlusPlus)
4719	RD = CXXRecordDecl::Create(C: Context, TK: TagTypeKind::Struct, DC, StartLoc: Loc, IdLoc: Loc,
4720	/*Id=*/nullptr);
4721	else
4722	RD = RecordDecl::Create(C: Context, TK: TagTypeKind::Struct, DC, StartLoc: Loc, IdLoc: Loc,
4723	/*Id=*/nullptr);
4724
4725	RD->setCapturedRecord();
4726	DC->addDecl(RD);
4727	RD->setImplicit();
4728	RD->startDefinition();
4729
4730	assert(NumParams > 0 && "CapturedStmt requires context parameter");
4731	CD = CapturedDecl::Create(C&: Context, DC: CurContext, NumParams);
4732	DC->addDecl(CD);
4733	return RD;
4734	}
4735
4736	static bool
4737	buildCapturedStmtCaptureList(Sema &S, CapturedRegionScopeInfo *RSI,
4738	SmallVectorImpl<CapturedStmt::Capture> &Captures,
4739	SmallVectorImpl<Expr *> &CaptureInits) {
4740	for (const sema::Capture &Cap : RSI->Captures) {
4741	if (Cap.isInvalid())
4742	continue;
4743
4744	// Form the initializer for the capture.
4745	ExprResult Init = S.BuildCaptureInit(Capture: Cap, ImplicitCaptureLoc: Cap.getLocation(),
4746	IsOpenMPMapping: RSI->CapRegionKind == CR_OpenMP);
4747
4748	// FIXME: Bail out now if the capture is not used and the initializer has
4749	// no side-effects.
4750
4751	// Create a field for this capture.
4752	FieldDecl *Field = S.BuildCaptureField(RD: RSI->TheRecordDecl, Capture: Cap);
4753
4754	// Add the capture to our list of captures.
4755	if (Cap.isThisCapture()) {
4756	Captures.push_back(Elt: CapturedStmt::Capture(Cap.getLocation(),
4757	CapturedStmt::VCK_This));
4758	} else if (Cap.isVLATypeCapture()) {
4759	Captures.push_back(
4760	Elt: CapturedStmt::Capture(Cap.getLocation(), CapturedStmt::VCK_VLAType));
4761	} else {
4762	assert(Cap.isVariableCapture() && "unknown kind of capture");
4763
4764	if (S.getLangOpts().OpenMP && RSI->CapRegionKind == CR_OpenMP)
4765	S.setOpenMPCaptureKind(FD: Field, D: Cap.getVariable(), Level: RSI->OpenMPLevel);
4766
4767	Captures.push_back(Elt: CapturedStmt::Capture(
4768	Cap.getLocation(),
4769	Cap.isReferenceCapture() ? CapturedStmt::VCK_ByRef
4770	: CapturedStmt::VCK_ByCopy,
4771	cast<VarDecl>(Val: Cap.getVariable())));
4772	}
4773	CaptureInits.push_back(Elt: Init.get());
4774	}
4775	return false;
4776	}
4777
4778	void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
4779	CapturedRegionKind Kind,
4780	unsigned NumParams) {
4781	CapturedDecl *CD = nullptr;
4782	RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, NumParams);
4783
4784	// Build the context parameter
4785	DeclContext *DC = CapturedDecl::castToDeclContext(D: CD);
4786	IdentifierInfo *ParamName = &Context.Idents.get(Name: "__context");
4787	QualType ParamType = Context.getPointerType(T: Context.getTagDeclType(RD));
4788	auto *Param =
4789	ImplicitParamDecl::Create(C&: Context, DC, IdLoc: Loc, Id: ParamName, T: ParamType,
4790	ParamKind: ImplicitParamKind::CapturedContext);
4791	DC->addDecl(D: Param);
4792
4793	CD->setContextParam(i: 0, P: Param);
4794
4795	// Enter the capturing scope for this captured region.
4796	PushCapturedRegionScope(RegionScope: CurScope, CD, RD, K: Kind);
4797
4798	if (CurScope)
4799	PushDeclContext(CurScope, CD);
4800	else
4801	CurContext = CD;
4802
4803	PushExpressionEvaluationContext(
4804	NewContext: ExpressionEvaluationContext::PotentiallyEvaluated);
4805	ExprEvalContexts.back().InImmediateEscalatingFunctionContext = false;
4806	}
4807
4808	void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
4809	CapturedRegionKind Kind,
4810	ArrayRef<CapturedParamNameType> Params,
4811	unsigned OpenMPCaptureLevel) {
4812	CapturedDecl *CD = nullptr;
4813	RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, NumParams: Params.size());
4814
4815	// Build the context parameter
4816	DeclContext *DC = CapturedDecl::castToDeclContext(D: CD);
4817	bool ContextIsFound = false;
4818	unsigned ParamNum = 0;
4819	for (ArrayRef<CapturedParamNameType>::iterator I = Params.begin(),
4820	E = Params.end();
4821	I != E; ++I, ++ParamNum) {
4822	if (I->second.isNull()) {
4823	assert(!ContextIsFound &&
4824	"null type has been found already for '__context' parameter");
4825	IdentifierInfo *ParamName = &Context.Idents.get(Name: "__context");
4826	QualType ParamType = Context.getPointerType(T: Context.getTagDeclType(RD))
4827	.withConst()
4828	.withRestrict();
4829	auto *Param =
4830	ImplicitParamDecl::Create(C&: Context, DC, IdLoc: Loc, Id: ParamName, T: ParamType,
4831	ParamKind: ImplicitParamKind::CapturedContext);
4832	DC->addDecl(D: Param);
4833	CD->setContextParam(i: ParamNum, P: Param);
4834	ContextIsFound = true;
4835	} else {
4836	IdentifierInfo *ParamName = &Context.Idents.get(Name: I->first);
4837	auto *Param =
4838	ImplicitParamDecl::Create(Context, DC, Loc, ParamName, I->second,
4839	ImplicitParamKind::CapturedContext);
4840	DC->addDecl(D: Param);
4841	CD->setParam(i: ParamNum, P: Param);
4842	}
4843	}
4844	assert(ContextIsFound && "no null type for '__context' parameter");
4845	if (!ContextIsFound) {
4846	// Add __context implicitly if it is not specified.
4847	IdentifierInfo *ParamName = &Context.Idents.get(Name: "__context");
4848	QualType ParamType = Context.getPointerType(T: Context.getTagDeclType(RD));
4849	auto *Param =
4850	ImplicitParamDecl::Create(C&: Context, DC, IdLoc: Loc, Id: ParamName, T: ParamType,
4851	ParamKind: ImplicitParamKind::CapturedContext);
4852	DC->addDecl(D: Param);
4853	CD->setContextParam(i: ParamNum, P: Param);
4854	}
4855	// Enter the capturing scope for this captured region.
4856	PushCapturedRegionScope(RegionScope: CurScope, CD, RD, K: Kind, OpenMPCaptureLevel);
4857
4858	if (CurScope)
4859	PushDeclContext(CurScope, CD);
4860	else
4861	CurContext = CD;
4862
4863	PushExpressionEvaluationContext(
4864	NewContext: ExpressionEvaluationContext::PotentiallyEvaluated);
4865	}
4866
4867	void Sema::ActOnCapturedRegionError() {
4868	DiscardCleanupsInEvaluationContext();
4869	PopExpressionEvaluationContext();
4870	PopDeclContext();
4871	PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo();
4872	CapturedRegionScopeInfo *RSI = cast<CapturedRegionScopeInfo>(Val: ScopeRAII.get());
4873
4874	RecordDecl *Record = RSI->TheRecordDecl;
4875	Record->setInvalidDecl();
4876
4877	SmallVector<Decl*, 4> Fields(Record->fields());
4878	ActOnFields(/*Scope=*/S: nullptr, RecLoc: Record->getLocation(), TagDecl: Record, Fields,
4879	LBrac: SourceLocation(), RBrac: SourceLocation(), AttrList: ParsedAttributesView());
4880	}
4881
4882	StmtResult Sema::ActOnCapturedRegionEnd(Stmt *S) {
4883	// Leave the captured scope before we start creating captures in the
4884	// enclosing scope.
4885	DiscardCleanupsInEvaluationContext();
4886	PopExpressionEvaluationContext();
4887	PopDeclContext();
4888	PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo();
4889	CapturedRegionScopeInfo *RSI = cast<CapturedRegionScopeInfo>(Val: ScopeRAII.get());
4890
4891	SmallVector<CapturedStmt::Capture, 4> Captures;
4892	SmallVector<Expr *, 4> CaptureInits;
4893	if (buildCapturedStmtCaptureList(S&: *this, RSI, Captures, CaptureInits))
4894	return StmtError();
4895
4896	CapturedDecl *CD = RSI->TheCapturedDecl;
4897	RecordDecl *RD = RSI->TheRecordDecl;
4898
4899	CapturedStmt *Res = CapturedStmt::Create(
4900	Context: getASTContext(), S, Kind: static_cast<CapturedRegionKind>(RSI->CapRegionKind),
4901	Captures, CaptureInits, CD, RD);
4902
4903	CD->setBody(Res->getCapturedStmt());
4904	RD->completeDefinition();
4905
4906	return Res;
4907	}
4908