xref: /freebsd/contrib/llvm-project/clang/lib/Sema/SemaStmt.cpp (revision 19261079b74319502c6ffa1249920079f0f69a72)
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/Sema/Ownership.h"
14 #include "clang/Sema/SemaInternal.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/ASTDiagnostic.h"
17 #include "clang/AST/ASTLambda.h"
18 #include "clang/AST/CharUnits.h"
19 #include "clang/AST/CXXInheritance.h"
20 #include "clang/AST/DeclObjC.h"
21 #include "clang/AST/EvaluatedExprVisitor.h"
22 #include "clang/AST/ExprCXX.h"
23 #include "clang/AST/ExprObjC.h"
24 #include "clang/AST/RecursiveASTVisitor.h"
25 #include "clang/AST/StmtCXX.h"
26 #include "clang/AST/StmtObjC.h"
27 #include "clang/AST/TypeLoc.h"
28 #include "clang/AST/TypeOrdering.h"
29 #include "clang/Basic/TargetInfo.h"
30 #include "clang/Lex/Preprocessor.h"
31 #include "clang/Sema/Initialization.h"
32 #include "clang/Sema/Lookup.h"
33 #include "clang/Sema/Scope.h"
34 #include "clang/Sema/ScopeInfo.h"
35 #include "llvm/ADT/ArrayRef.h"
36 #include "llvm/ADT/DenseMap.h"
37 #include "llvm/ADT/STLExtras.h"
38 #include "llvm/ADT/SmallPtrSet.h"
39 #include "llvm/ADT/SmallString.h"
40 #include "llvm/ADT/SmallVector.h"
41 
42 using namespace clang;
43 using namespace sema;
44 
45 StmtResult Sema::ActOnExprStmt(ExprResult FE, bool DiscardedValue) {
46   if (FE.isInvalid())
47     return StmtError();
48 
49   FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(), DiscardedValue);
50   if (FE.isInvalid())
51     return StmtError();
52 
53   // C99 6.8.3p2: The expression in an expression statement is evaluated as a
54   // void expression for its side effects.  Conversion to void allows any
55   // operand, even incomplete types.
56 
57   // Same thing in for stmt first clause (when expr) and third clause.
58   return StmtResult(FE.getAs<Stmt>());
59 }
60 
61 
62 StmtResult Sema::ActOnExprStmtError() {
63   DiscardCleanupsInEvaluationContext();
64   return StmtError();
65 }
66 
67 StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc,
68                                bool HasLeadingEmptyMacro) {
69   return new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro);
70 }
71 
72 StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc,
73                                SourceLocation EndLoc) {
74   DeclGroupRef DG = dg.get();
75 
76   // If we have an invalid decl, just return an error.
77   if (DG.isNull()) return StmtError();
78 
79   return new (Context) DeclStmt(DG, StartLoc, EndLoc);
80 }
81 
82 void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
83   DeclGroupRef DG = dg.get();
84 
85   // If we don't have a declaration, or we have an invalid declaration,
86   // just return.
87   if (DG.isNull() || !DG.isSingleDecl())
88     return;
89 
90   Decl *decl = DG.getSingleDecl();
91   if (!decl || decl->isInvalidDecl())
92     return;
93 
94   // Only variable declarations are permitted.
95   VarDecl *var = dyn_cast<VarDecl>(decl);
96   if (!var) {
97     Diag(decl->getLocation(), diag::err_non_variable_decl_in_for);
98     decl->setInvalidDecl();
99     return;
100   }
101 
102   // foreach variables are never actually initialized in the way that
103   // the parser came up with.
104   var->setInit(nullptr);
105 
106   // In ARC, we don't need to retain the iteration variable of a fast
107   // enumeration loop.  Rather than actually trying to catch that
108   // during declaration processing, we remove the consequences here.
109   if (getLangOpts().ObjCAutoRefCount) {
110     QualType type = var->getType();
111 
112     // Only do this if we inferred the lifetime.  Inferred lifetime
113     // will show up as a local qualifier because explicit lifetime
114     // should have shown up as an AttributedType instead.
115     if (type.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong) {
116       // Add 'const' and mark the variable as pseudo-strong.
117       var->setType(type.withConst());
118       var->setARCPseudoStrong(true);
119     }
120   }
121 }
122 
123 /// Diagnose unused comparisons, both builtin and overloaded operators.
124 /// For '==' and '!=', suggest fixits for '=' or '|='.
125 ///
126 /// Adding a cast to void (or other expression wrappers) will prevent the
127 /// warning from firing.
128 static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) {
129   SourceLocation Loc;
130   bool CanAssign;
131   enum { Equality, Inequality, Relational, ThreeWay } Kind;
132 
133   if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
134     if (!Op->isComparisonOp())
135       return false;
136 
137     if (Op->getOpcode() == BO_EQ)
138       Kind = Equality;
139     else if (Op->getOpcode() == BO_NE)
140       Kind = Inequality;
141     else if (Op->getOpcode() == BO_Cmp)
142       Kind = ThreeWay;
143     else {
144       assert(Op->isRelationalOp());
145       Kind = Relational;
146     }
147     Loc = Op->getOperatorLoc();
148     CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
149   } else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
150     switch (Op->getOperator()) {
151     case OO_EqualEqual:
152       Kind = Equality;
153       break;
154     case OO_ExclaimEqual:
155       Kind = Inequality;
156       break;
157     case OO_Less:
158     case OO_Greater:
159     case OO_GreaterEqual:
160     case OO_LessEqual:
161       Kind = Relational;
162       break;
163     case OO_Spaceship:
164       Kind = ThreeWay;
165       break;
166     default:
167       return false;
168     }
169 
170     Loc = Op->getOperatorLoc();
171     CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
172   } else {
173     // Not a typo-prone comparison.
174     return false;
175   }
176 
177   // Suppress warnings when the operator, suspicious as it may be, comes from
178   // a macro expansion.
179   if (S.SourceMgr.isMacroBodyExpansion(Loc))
180     return false;
181 
182   S.Diag(Loc, diag::warn_unused_comparison)
183     << (unsigned)Kind << E->getSourceRange();
184 
185   // If the LHS is a plausible entity to assign to, provide a fixit hint to
186   // correct common typos.
187   if (CanAssign) {
188     if (Kind == Inequality)
189       S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
190         << FixItHint::CreateReplacement(Loc, "|=");
191     else if (Kind == Equality)
192       S.Diag(Loc, diag::note_equality_comparison_to_assign)
193         << FixItHint::CreateReplacement(Loc, "=");
194   }
195 
196   return true;
197 }
198 
199 static bool DiagnoseNoDiscard(Sema &S, const WarnUnusedResultAttr *A,
200                               SourceLocation Loc, SourceRange R1,
201                               SourceRange R2, bool IsCtor) {
202   if (!A)
203     return false;
204   StringRef Msg = A->getMessage();
205 
206   if (Msg.empty()) {
207     if (IsCtor)
208       return S.Diag(Loc, diag::warn_unused_constructor) << A << R1 << R2;
209     return S.Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
210   }
211 
212   if (IsCtor)
213     return S.Diag(Loc, diag::warn_unused_constructor_msg) << A << Msg << R1
214                                                           << R2;
215   return S.Diag(Loc, diag::warn_unused_result_msg) << A << Msg << R1 << R2;
216 }
217 
218 void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
219   if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
220     return DiagnoseUnusedExprResult(Label->getSubStmt());
221 
222   const Expr *E = dyn_cast_or_null<Expr>(S);
223   if (!E)
224     return;
225 
226   // If we are in an unevaluated expression context, then there can be no unused
227   // results because the results aren't expected to be used in the first place.
228   if (isUnevaluatedContext())
229     return;
230 
231   SourceLocation ExprLoc = E->IgnoreParenImpCasts()->getExprLoc();
232   // In most cases, we don't want to warn if the expression is written in a
233   // macro body, or if the macro comes from a system header. If the offending
234   // expression is a call to a function with the warn_unused_result attribute,
235   // we warn no matter the location. Because of the order in which the various
236   // checks need to happen, we factor out the macro-related test here.
237   bool ShouldSuppress =
238       SourceMgr.isMacroBodyExpansion(ExprLoc) ||
239       SourceMgr.isInSystemMacro(ExprLoc);
240 
241   const Expr *WarnExpr;
242   SourceLocation Loc;
243   SourceRange R1, R2;
244   if (!E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context))
245     return;
246 
247   // If this is a GNU statement expression expanded from a macro, it is probably
248   // unused because it is a function-like macro that can be used as either an
249   // expression or statement.  Don't warn, because it is almost certainly a
250   // false positive.
251   if (isa<StmtExpr>(E) && Loc.isMacroID())
252     return;
253 
254   // Check if this is the UNREFERENCED_PARAMETER from the Microsoft headers.
255   // That macro is frequently used to suppress "unused parameter" warnings,
256   // but its implementation makes clang's -Wunused-value fire.  Prevent this.
257   if (isa<ParenExpr>(E->IgnoreImpCasts()) && Loc.isMacroID()) {
258     SourceLocation SpellLoc = Loc;
259     if (findMacroSpelling(SpellLoc, "UNREFERENCED_PARAMETER"))
260       return;
261   }
262 
263   // Okay, we have an unused result.  Depending on what the base expression is,
264   // we might want to make a more specific diagnostic.  Check for one of these
265   // cases now.
266   unsigned DiagID = diag::warn_unused_expr;
267   if (const FullExpr *Temps = dyn_cast<FullExpr>(E))
268     E = Temps->getSubExpr();
269   if (const CXXBindTemporaryExpr *TempExpr = dyn_cast<CXXBindTemporaryExpr>(E))
270     E = TempExpr->getSubExpr();
271 
272   if (DiagnoseUnusedComparison(*this, E))
273     return;
274 
275   E = WarnExpr;
276   if (const auto *Cast = dyn_cast<CastExpr>(E))
277     if (Cast->getCastKind() == CK_NoOp ||
278         Cast->getCastKind() == CK_ConstructorConversion)
279       E = Cast->getSubExpr()->IgnoreImpCasts();
280 
281   if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
282     if (E->getType()->isVoidType())
283       return;
284 
285     if (DiagnoseNoDiscard(*this, cast_or_null<WarnUnusedResultAttr>(
286                                      CE->getUnusedResultAttr(Context)),
287                           Loc, R1, R2, /*isCtor=*/false))
288       return;
289 
290     // If the callee has attribute pure, const, or warn_unused_result, warn with
291     // a more specific message to make it clear what is happening. If the call
292     // is written in a macro body, only warn if it has the warn_unused_result
293     // attribute.
294     if (const Decl *FD = CE->getCalleeDecl()) {
295       if (ShouldSuppress)
296         return;
297       if (FD->hasAttr<PureAttr>()) {
298         Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
299         return;
300       }
301       if (FD->hasAttr<ConstAttr>()) {
302         Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
303         return;
304       }
305     }
306   } else if (const auto *CE = dyn_cast<CXXConstructExpr>(E)) {
307     if (const CXXConstructorDecl *Ctor = CE->getConstructor()) {
308       const auto *A = Ctor->getAttr<WarnUnusedResultAttr>();
309       A = A ? A : Ctor->getParent()->getAttr<WarnUnusedResultAttr>();
310       if (DiagnoseNoDiscard(*this, A, Loc, R1, R2, /*isCtor=*/true))
311         return;
312     }
313   } else if (const auto *ILE = dyn_cast<InitListExpr>(E)) {
314     if (const TagDecl *TD = ILE->getType()->getAsTagDecl()) {
315 
316       if (DiagnoseNoDiscard(*this, TD->getAttr<WarnUnusedResultAttr>(), Loc, R1,
317                             R2, /*isCtor=*/false))
318         return;
319     }
320   } else if (ShouldSuppress)
321     return;
322 
323   E = WarnExpr;
324   if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
325     if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) {
326       Diag(Loc, diag::err_arc_unused_init_message) << R1;
327       return;
328     }
329     const ObjCMethodDecl *MD = ME->getMethodDecl();
330     if (MD) {
331       if (DiagnoseNoDiscard(*this, MD->getAttr<WarnUnusedResultAttr>(), Loc, R1,
332                             R2, /*isCtor=*/false))
333         return;
334     }
335   } else if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
336     const Expr *Source = POE->getSyntacticForm();
337     // Handle the actually selected call of an OpenMP specialized call.
338     if (LangOpts.OpenMP && isa<CallExpr>(Source) &&
339         POE->getNumSemanticExprs() == 1 &&
340         isa<CallExpr>(POE->getSemanticExpr(0)))
341       return DiagnoseUnusedExprResult(POE->getSemanticExpr(0));
342     if (isa<ObjCSubscriptRefExpr>(Source))
343       DiagID = diag::warn_unused_container_subscript_expr;
344     else
345       DiagID = diag::warn_unused_property_expr;
346   } else if (const CXXFunctionalCastExpr *FC
347                                        = dyn_cast<CXXFunctionalCastExpr>(E)) {
348     const Expr *E = FC->getSubExpr();
349     if (const CXXBindTemporaryExpr *TE = dyn_cast<CXXBindTemporaryExpr>(E))
350       E = TE->getSubExpr();
351     if (isa<CXXTemporaryObjectExpr>(E))
352       return;
353     if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(E))
354       if (const CXXRecordDecl *RD = CE->getType()->getAsCXXRecordDecl())
355         if (!RD->getAttr<WarnUnusedAttr>())
356           return;
357   }
358   // Diagnose "(void*) blah" as a typo for "(void) blah".
359   else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
360     TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
361     QualType T = TI->getType();
362 
363     // We really do want to use the non-canonical type here.
364     if (T == Context.VoidPtrTy) {
365       PointerTypeLoc TL = TI->getTypeLoc().castAs<PointerTypeLoc>();
366 
367       Diag(Loc, diag::warn_unused_voidptr)
368         << FixItHint::CreateRemoval(TL.getStarLoc());
369       return;
370     }
371   }
372 
373   // Tell the user to assign it into a variable to force a volatile load if this
374   // isn't an array.
375   if (E->isGLValue() && E->getType().isVolatileQualified() &&
376       !E->getType()->isArrayType()) {
377     Diag(Loc, diag::warn_unused_volatile) << R1 << R2;
378     return;
379   }
380 
381   DiagRuntimeBehavior(Loc, nullptr, PDiag(DiagID) << R1 << R2);
382 }
383 
384 void Sema::ActOnStartOfCompoundStmt(bool IsStmtExpr) {
385   PushCompoundScope(IsStmtExpr);
386 }
387 
388 void Sema::ActOnAfterCompoundStatementLeadingPragmas() {
389   if (getCurFPFeatures().isFPConstrained()) {
390     FunctionScopeInfo *FSI = getCurFunction();
391     assert(FSI);
392     FSI->setUsesFPIntrin();
393   }
394 }
395 
396 void Sema::ActOnFinishOfCompoundStmt() {
397   PopCompoundScope();
398 }
399 
400 sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
401   return getCurFunction()->CompoundScopes.back();
402 }
403 
404 StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
405                                    ArrayRef<Stmt *> Elts, bool isStmtExpr) {
406   const unsigned NumElts = Elts.size();
407 
408   // If we're in C89 mode, check that we don't have any decls after stmts.  If
409   // so, emit an extension diagnostic.
410   if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
411     // Note that __extension__ can be around a decl.
412     unsigned i = 0;
413     // Skip over all declarations.
414     for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
415       /*empty*/;
416 
417     // We found the end of the list or a statement.  Scan for another declstmt.
418     for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
419       /*empty*/;
420 
421     if (i != NumElts) {
422       Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
423       Diag(D->getLocation(), diag::ext_mixed_decls_code);
424     }
425   }
426 
427   // Check for suspicious empty body (null statement) in `for' and `while'
428   // statements.  Don't do anything for template instantiations, this just adds
429   // noise.
430   if (NumElts != 0 && !CurrentInstantiationScope &&
431       getCurCompoundScope().HasEmptyLoopBodies) {
432     for (unsigned i = 0; i != NumElts - 1; ++i)
433       DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]);
434   }
435 
436   return CompoundStmt::Create(Context, Elts, L, R);
437 }
438 
439 ExprResult
440 Sema::ActOnCaseExpr(SourceLocation CaseLoc, ExprResult Val) {
441   if (!Val.get())
442     return Val;
443 
444   if (DiagnoseUnexpandedParameterPack(Val.get()))
445     return ExprError();
446 
447   // If we're not inside a switch, let the 'case' statement handling diagnose
448   // this. Just clean up after the expression as best we can.
449   if (getCurFunction()->SwitchStack.empty())
450     return ActOnFinishFullExpr(Val.get(), Val.get()->getExprLoc(), false,
451                                getLangOpts().CPlusPlus11);
452 
453   Expr *CondExpr =
454       getCurFunction()->SwitchStack.back().getPointer()->getCond();
455   if (!CondExpr)
456     return ExprError();
457   QualType CondType = CondExpr->getType();
458 
459   auto CheckAndFinish = [&](Expr *E) {
460     if (CondType->isDependentType() || E->isTypeDependent())
461       return ExprResult(E);
462 
463     if (getLangOpts().CPlusPlus11) {
464       // C++11 [stmt.switch]p2: the constant-expression shall be a converted
465       // constant expression of the promoted type of the switch condition.
466       llvm::APSInt TempVal;
467       return CheckConvertedConstantExpression(E, CondType, TempVal,
468                                               CCEK_CaseValue);
469     }
470 
471     ExprResult ER = E;
472     if (!E->isValueDependent())
473       ER = VerifyIntegerConstantExpression(E, AllowFold);
474     if (!ER.isInvalid())
475       ER = DefaultLvalueConversion(ER.get());
476     if (!ER.isInvalid())
477       ER = ImpCastExprToType(ER.get(), CondType, CK_IntegralCast);
478     if (!ER.isInvalid())
479       ER = ActOnFinishFullExpr(ER.get(), ER.get()->getExprLoc(), false);
480     return ER;
481   };
482 
483   ExprResult Converted = CorrectDelayedTyposInExpr(
484       Val, /*InitDecl=*/nullptr, /*RecoverUncorrectedTypos=*/false,
485       CheckAndFinish);
486   if (Converted.get() == Val.get())
487     Converted = CheckAndFinish(Val.get());
488   return Converted;
489 }
490 
491 StmtResult
492 Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHSVal,
493                     SourceLocation DotDotDotLoc, ExprResult RHSVal,
494                     SourceLocation ColonLoc) {
495   assert((LHSVal.isInvalid() || LHSVal.get()) && "missing LHS value");
496   assert((DotDotDotLoc.isInvalid() ? RHSVal.isUnset()
497                                    : RHSVal.isInvalid() || RHSVal.get()) &&
498          "missing RHS value");
499 
500   if (getCurFunction()->SwitchStack.empty()) {
501     Diag(CaseLoc, diag::err_case_not_in_switch);
502     return StmtError();
503   }
504 
505   if (LHSVal.isInvalid() || RHSVal.isInvalid()) {
506     getCurFunction()->SwitchStack.back().setInt(true);
507     return StmtError();
508   }
509 
510   auto *CS = CaseStmt::Create(Context, LHSVal.get(), RHSVal.get(),
511                               CaseLoc, DotDotDotLoc, ColonLoc);
512   getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(CS);
513   return CS;
514 }
515 
516 /// ActOnCaseStmtBody - This installs a statement as the body of a case.
517 void Sema::ActOnCaseStmtBody(Stmt *S, Stmt *SubStmt) {
518   cast<CaseStmt>(S)->setSubStmt(SubStmt);
519 }
520 
521 StmtResult
522 Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
523                        Stmt *SubStmt, Scope *CurScope) {
524   if (getCurFunction()->SwitchStack.empty()) {
525     Diag(DefaultLoc, diag::err_default_not_in_switch);
526     return SubStmt;
527   }
528 
529   DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
530   getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(DS);
531   return DS;
532 }
533 
534 StmtResult
535 Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
536                      SourceLocation ColonLoc, Stmt *SubStmt) {
537   // If the label was multiply defined, reject it now.
538   if (TheDecl->getStmt()) {
539     Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName();
540     Diag(TheDecl->getLocation(), diag::note_previous_definition);
541     return SubStmt;
542   }
543 
544   // Otherwise, things are good.  Fill in the declaration and return it.
545   LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt);
546   TheDecl->setStmt(LS);
547   if (!TheDecl->isGnuLocal()) {
548     TheDecl->setLocStart(IdentLoc);
549     if (!TheDecl->isMSAsmLabel()) {
550       // Don't update the location of MS ASM labels.  These will result in
551       // a diagnostic, and changing the location here will mess that up.
552       TheDecl->setLocation(IdentLoc);
553     }
554   }
555   return LS;
556 }
557 
558 StmtResult Sema::ActOnAttributedStmt(SourceLocation AttrLoc,
559                                      ArrayRef<const Attr*> Attrs,
560                                      Stmt *SubStmt) {
561   // Fill in the declaration and return it.
562   AttributedStmt *LS = AttributedStmt::Create(Context, AttrLoc, Attrs, SubStmt);
563   return LS;
564 }
565 
566 namespace {
567 class CommaVisitor : public EvaluatedExprVisitor<CommaVisitor> {
568   typedef EvaluatedExprVisitor<CommaVisitor> Inherited;
569   Sema &SemaRef;
570 public:
571   CommaVisitor(Sema &SemaRef) : Inherited(SemaRef.Context), SemaRef(SemaRef) {}
572   void VisitBinaryOperator(BinaryOperator *E) {
573     if (E->getOpcode() == BO_Comma)
574       SemaRef.DiagnoseCommaOperator(E->getLHS(), E->getExprLoc());
575     EvaluatedExprVisitor<CommaVisitor>::VisitBinaryOperator(E);
576   }
577 };
578 }
579 
580 StmtResult Sema::ActOnIfStmt(SourceLocation IfLoc, bool IsConstexpr,
581                              SourceLocation LParenLoc, Stmt *InitStmt,
582                              ConditionResult Cond, SourceLocation RParenLoc,
583                              Stmt *thenStmt, SourceLocation ElseLoc,
584                              Stmt *elseStmt) {
585   if (Cond.isInvalid())
586     Cond = ConditionResult(
587         *this, nullptr,
588         MakeFullExpr(new (Context) OpaqueValueExpr(SourceLocation(),
589                                                    Context.BoolTy, VK_RValue),
590                      IfLoc),
591         false);
592 
593   Expr *CondExpr = Cond.get().second;
594   // Only call the CommaVisitor when not C89 due to differences in scope flags.
595   if ((getLangOpts().C99 || getLangOpts().CPlusPlus) &&
596       !Diags.isIgnored(diag::warn_comma_operator, CondExpr->getExprLoc()))
597     CommaVisitor(*this).Visit(CondExpr);
598 
599   if (!elseStmt)
600     DiagnoseEmptyStmtBody(CondExpr->getEndLoc(), thenStmt,
601                           diag::warn_empty_if_body);
602 
603   if (IsConstexpr) {
604     auto DiagnoseLikelihood = [&](const Stmt *S) {
605       if (const Attr *A = Stmt::getLikelihoodAttr(S)) {
606         Diags.Report(A->getLocation(),
607                      diag::warn_attribute_has_no_effect_on_if_constexpr)
608             << A << A->getRange();
609         Diags.Report(IfLoc,
610                      diag::note_attribute_has_no_effect_on_if_constexpr_here)
611             << SourceRange(IfLoc, LParenLoc.getLocWithOffset(-1));
612       }
613     };
614     DiagnoseLikelihood(thenStmt);
615     DiagnoseLikelihood(elseStmt);
616   } else {
617     std::tuple<bool, const Attr *, const Attr *> LHC =
618         Stmt::determineLikelihoodConflict(thenStmt, elseStmt);
619     if (std::get<0>(LHC)) {
620       const Attr *ThenAttr = std::get<1>(LHC);
621       const Attr *ElseAttr = std::get<2>(LHC);
622       Diags.Report(ThenAttr->getLocation(),
623                    diag::warn_attributes_likelihood_ifstmt_conflict)
624           << ThenAttr << ThenAttr->getRange();
625       Diags.Report(ElseAttr->getLocation(), diag::note_conflicting_attribute)
626           << ElseAttr << ElseAttr->getRange();
627     }
628   }
629 
630   return BuildIfStmt(IfLoc, IsConstexpr, LParenLoc, InitStmt, Cond, RParenLoc,
631                      thenStmt, ElseLoc, elseStmt);
632 }
633 
634 StmtResult Sema::BuildIfStmt(SourceLocation IfLoc, bool IsConstexpr,
635                              SourceLocation LParenLoc, Stmt *InitStmt,
636                              ConditionResult Cond, SourceLocation RParenLoc,
637                              Stmt *thenStmt, SourceLocation ElseLoc,
638                              Stmt *elseStmt) {
639   if (Cond.isInvalid())
640     return StmtError();
641 
642   if (IsConstexpr || isa<ObjCAvailabilityCheckExpr>(Cond.get().second))
643     setFunctionHasBranchProtectedScope();
644 
645   return IfStmt::Create(Context, IfLoc, IsConstexpr, InitStmt, Cond.get().first,
646                         Cond.get().second, LParenLoc, RParenLoc, thenStmt,
647                         ElseLoc, elseStmt);
648 }
649 
650 namespace {
651   struct CaseCompareFunctor {
652     bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
653                     const llvm::APSInt &RHS) {
654       return LHS.first < RHS;
655     }
656     bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
657                     const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
658       return LHS.first < RHS.first;
659     }
660     bool operator()(const llvm::APSInt &LHS,
661                     const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
662       return LHS < RHS.first;
663     }
664   };
665 }
666 
667 /// CmpCaseVals - Comparison predicate for sorting case values.
668 ///
669 static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
670                         const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
671   if (lhs.first < rhs.first)
672     return true;
673 
674   if (lhs.first == rhs.first &&
675       lhs.second->getCaseLoc() < rhs.second->getCaseLoc())
676     return true;
677   return false;
678 }
679 
680 /// CmpEnumVals - Comparison predicate for sorting enumeration values.
681 ///
682 static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
683                         const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
684 {
685   return lhs.first < rhs.first;
686 }
687 
688 /// EqEnumVals - Comparison preficate for uniqing enumeration values.
689 ///
690 static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
691                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
692 {
693   return lhs.first == rhs.first;
694 }
695 
696 /// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
697 /// potentially integral-promoted expression @p expr.
698 static QualType GetTypeBeforeIntegralPromotion(const Expr *&E) {
699   if (const auto *FE = dyn_cast<FullExpr>(E))
700     E = FE->getSubExpr();
701   while (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
702     if (ImpCast->getCastKind() != CK_IntegralCast) break;
703     E = ImpCast->getSubExpr();
704   }
705   return E->getType();
706 }
707 
708 ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) {
709   class SwitchConvertDiagnoser : public ICEConvertDiagnoser {
710     Expr *Cond;
711 
712   public:
713     SwitchConvertDiagnoser(Expr *Cond)
714         : ICEConvertDiagnoser(/*AllowScopedEnumerations*/true, false, true),
715           Cond(Cond) {}
716 
717     SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
718                                          QualType T) override {
719       return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T;
720     }
721 
722     SemaDiagnosticBuilder diagnoseIncomplete(
723         Sema &S, SourceLocation Loc, QualType T) override {
724       return S.Diag(Loc, diag::err_switch_incomplete_class_type)
725                << T << Cond->getSourceRange();
726     }
727 
728     SemaDiagnosticBuilder diagnoseExplicitConv(
729         Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
730       return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy;
731     }
732 
733     SemaDiagnosticBuilder noteExplicitConv(
734         Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
735       return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
736         << ConvTy->isEnumeralType() << ConvTy;
737     }
738 
739     SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
740                                             QualType T) override {
741       return S.Diag(Loc, diag::err_switch_multiple_conversions) << T;
742     }
743 
744     SemaDiagnosticBuilder noteAmbiguous(
745         Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
746       return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
747       << ConvTy->isEnumeralType() << ConvTy;
748     }
749 
750     SemaDiagnosticBuilder diagnoseConversion(
751         Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
752       llvm_unreachable("conversion functions are permitted");
753     }
754   } SwitchDiagnoser(Cond);
755 
756   ExprResult CondResult =
757       PerformContextualImplicitConversion(SwitchLoc, Cond, SwitchDiagnoser);
758   if (CondResult.isInvalid())
759     return ExprError();
760 
761   // FIXME: PerformContextualImplicitConversion doesn't always tell us if it
762   // failed and produced a diagnostic.
763   Cond = CondResult.get();
764   if (!Cond->isTypeDependent() &&
765       !Cond->getType()->isIntegralOrEnumerationType())
766     return ExprError();
767 
768   // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
769   return UsualUnaryConversions(Cond);
770 }
771 
772 StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
773                                         SourceLocation LParenLoc,
774                                         Stmt *InitStmt, ConditionResult Cond,
775                                         SourceLocation RParenLoc) {
776   Expr *CondExpr = Cond.get().second;
777   assert((Cond.isInvalid() || CondExpr) && "switch with no condition");
778 
779   if (CondExpr && !CondExpr->isTypeDependent()) {
780     // We have already converted the expression to an integral or enumeration
781     // type, when we parsed the switch condition. There are cases where we don't
782     // have an appropriate type, e.g. a typo-expr Cond was corrected to an
783     // inappropriate-type expr, we just return an error.
784     if (!CondExpr->getType()->isIntegralOrEnumerationType())
785       return StmtError();
786     if (CondExpr->isKnownToHaveBooleanValue()) {
787       // switch(bool_expr) {...} is often a programmer error, e.g.
788       //   switch(n && mask) { ... }  // Doh - should be "n & mask".
789       // One can always use an if statement instead of switch(bool_expr).
790       Diag(SwitchLoc, diag::warn_bool_switch_condition)
791           << CondExpr->getSourceRange();
792     }
793   }
794 
795   setFunctionHasBranchIntoScope();
796 
797   auto *SS = SwitchStmt::Create(Context, InitStmt, Cond.get().first, CondExpr,
798                                 LParenLoc, RParenLoc);
799   getCurFunction()->SwitchStack.push_back(
800       FunctionScopeInfo::SwitchInfo(SS, false));
801   return SS;
802 }
803 
804 static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
805   Val = Val.extOrTrunc(BitWidth);
806   Val.setIsSigned(IsSigned);
807 }
808 
809 /// Check the specified case value is in range for the given unpromoted switch
810 /// type.
811 static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val,
812                            unsigned UnpromotedWidth, bool UnpromotedSign) {
813   // In C++11 onwards, this is checked by the language rules.
814   if (S.getLangOpts().CPlusPlus11)
815     return;
816 
817   // If the case value was signed and negative and the switch expression is
818   // unsigned, don't bother to warn: this is implementation-defined behavior.
819   // FIXME: Introduce a second, default-ignored warning for this case?
820   if (UnpromotedWidth < Val.getBitWidth()) {
821     llvm::APSInt ConvVal(Val);
822     AdjustAPSInt(ConvVal, UnpromotedWidth, UnpromotedSign);
823     AdjustAPSInt(ConvVal, Val.getBitWidth(), Val.isSigned());
824     // FIXME: Use different diagnostics for overflow  in conversion to promoted
825     // type versus "switch expression cannot have this value". Use proper
826     // IntRange checking rather than just looking at the unpromoted type here.
827     if (ConvVal != Val)
828       S.Diag(Loc, diag::warn_case_value_overflow) << Val.toString(10)
829                                                   << ConvVal.toString(10);
830   }
831 }
832 
833 typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
834 
835 /// Returns true if we should emit a diagnostic about this case expression not
836 /// being a part of the enum used in the switch controlling expression.
837 static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
838                                               const EnumDecl *ED,
839                                               const Expr *CaseExpr,
840                                               EnumValsTy::iterator &EI,
841                                               EnumValsTy::iterator &EIEnd,
842                                               const llvm::APSInt &Val) {
843   if (!ED->isClosed())
844     return false;
845 
846   if (const DeclRefExpr *DRE =
847           dyn_cast<DeclRefExpr>(CaseExpr->IgnoreParenImpCasts())) {
848     if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
849       QualType VarType = VD->getType();
850       QualType EnumType = S.Context.getTypeDeclType(ED);
851       if (VD->hasGlobalStorage() && VarType.isConstQualified() &&
852           S.Context.hasSameUnqualifiedType(EnumType, VarType))
853         return false;
854     }
855   }
856 
857   if (ED->hasAttr<FlagEnumAttr>())
858     return !S.IsValueInFlagEnum(ED, Val, false);
859 
860   while (EI != EIEnd && EI->first < Val)
861     EI++;
862 
863   if (EI != EIEnd && EI->first == Val)
864     return false;
865 
866   return true;
867 }
868 
869 static void checkEnumTypesInSwitchStmt(Sema &S, const Expr *Cond,
870                                        const Expr *Case) {
871   QualType CondType = Cond->getType();
872   QualType CaseType = Case->getType();
873 
874   const EnumType *CondEnumType = CondType->getAs<EnumType>();
875   const EnumType *CaseEnumType = CaseType->getAs<EnumType>();
876   if (!CondEnumType || !CaseEnumType)
877     return;
878 
879   // Ignore anonymous enums.
880   if (!CondEnumType->getDecl()->getIdentifier() &&
881       !CondEnumType->getDecl()->getTypedefNameForAnonDecl())
882     return;
883   if (!CaseEnumType->getDecl()->getIdentifier() &&
884       !CaseEnumType->getDecl()->getTypedefNameForAnonDecl())
885     return;
886 
887   if (S.Context.hasSameUnqualifiedType(CondType, CaseType))
888     return;
889 
890   S.Diag(Case->getExprLoc(), diag::warn_comparison_of_mixed_enum_types_switch)
891       << CondType << CaseType << Cond->getSourceRange()
892       << Case->getSourceRange();
893 }
894 
895 StmtResult
896 Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
897                             Stmt *BodyStmt) {
898   SwitchStmt *SS = cast<SwitchStmt>(Switch);
899   bool CaseListIsIncomplete = getCurFunction()->SwitchStack.back().getInt();
900   assert(SS == getCurFunction()->SwitchStack.back().getPointer() &&
901          "switch stack missing push/pop!");
902 
903   getCurFunction()->SwitchStack.pop_back();
904 
905   if (!BodyStmt) return StmtError();
906   SS->setBody(BodyStmt, SwitchLoc);
907 
908   Expr *CondExpr = SS->getCond();
909   if (!CondExpr) return StmtError();
910 
911   QualType CondType = CondExpr->getType();
912 
913   // C++ 6.4.2.p2:
914   // Integral promotions are performed (on the switch condition).
915   //
916   // A case value unrepresentable by the original switch condition
917   // type (before the promotion) doesn't make sense, even when it can
918   // be represented by the promoted type.  Therefore we need to find
919   // the pre-promotion type of the switch condition.
920   const Expr *CondExprBeforePromotion = CondExpr;
921   QualType CondTypeBeforePromotion =
922       GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
923 
924   // Get the bitwidth of the switched-on value after promotions. We must
925   // convert the integer case values to this width before comparison.
926   bool HasDependentValue
927     = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
928   unsigned CondWidth = HasDependentValue ? 0 : Context.getIntWidth(CondType);
929   bool CondIsSigned = CondType->isSignedIntegerOrEnumerationType();
930 
931   // Get the width and signedness that the condition might actually have, for
932   // warning purposes.
933   // FIXME: Grab an IntRange for the condition rather than using the unpromoted
934   // type.
935   unsigned CondWidthBeforePromotion
936     = HasDependentValue ? 0 : Context.getIntWidth(CondTypeBeforePromotion);
937   bool CondIsSignedBeforePromotion
938     = CondTypeBeforePromotion->isSignedIntegerOrEnumerationType();
939 
940   // Accumulate all of the case values in a vector so that we can sort them
941   // and detect duplicates.  This vector contains the APInt for the case after
942   // it has been converted to the condition type.
943   typedef SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
944   CaseValsTy CaseVals;
945 
946   // Keep track of any GNU case ranges we see.  The APSInt is the low value.
947   typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
948   CaseRangesTy CaseRanges;
949 
950   DefaultStmt *TheDefaultStmt = nullptr;
951 
952   bool CaseListIsErroneous = false;
953 
954   for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
955        SC = SC->getNextSwitchCase()) {
956 
957     if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
958       if (TheDefaultStmt) {
959         Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
960         Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
961 
962         // FIXME: Remove the default statement from the switch block so that
963         // we'll return a valid AST.  This requires recursing down the AST and
964         // finding it, not something we are set up to do right now.  For now,
965         // just lop the entire switch stmt out of the AST.
966         CaseListIsErroneous = true;
967       }
968       TheDefaultStmt = DS;
969 
970     } else {
971       CaseStmt *CS = cast<CaseStmt>(SC);
972 
973       Expr *Lo = CS->getLHS();
974 
975       if (Lo->isValueDependent()) {
976         HasDependentValue = true;
977         break;
978       }
979 
980       // We already verified that the expression has a constant value;
981       // get that value (prior to conversions).
982       const Expr *LoBeforePromotion = Lo;
983       GetTypeBeforeIntegralPromotion(LoBeforePromotion);
984       llvm::APSInt LoVal = LoBeforePromotion->EvaluateKnownConstInt(Context);
985 
986       // Check the unconverted value is within the range of possible values of
987       // the switch expression.
988       checkCaseValue(*this, Lo->getBeginLoc(), LoVal, CondWidthBeforePromotion,
989                      CondIsSignedBeforePromotion);
990 
991       // FIXME: This duplicates the check performed for warn_not_in_enum below.
992       checkEnumTypesInSwitchStmt(*this, CondExprBeforePromotion,
993                                  LoBeforePromotion);
994 
995       // Convert the value to the same width/sign as the condition.
996       AdjustAPSInt(LoVal, CondWidth, CondIsSigned);
997 
998       // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
999       if (CS->getRHS()) {
1000         if (CS->getRHS()->isValueDependent()) {
1001           HasDependentValue = true;
1002           break;
1003         }
1004         CaseRanges.push_back(std::make_pair(LoVal, CS));
1005       } else
1006         CaseVals.push_back(std::make_pair(LoVal, CS));
1007     }
1008   }
1009 
1010   if (!HasDependentValue) {
1011     // If we don't have a default statement, check whether the
1012     // condition is constant.
1013     llvm::APSInt ConstantCondValue;
1014     bool HasConstantCond = false;
1015     if (!TheDefaultStmt) {
1016       Expr::EvalResult Result;
1017       HasConstantCond = CondExpr->EvaluateAsInt(Result, Context,
1018                                                 Expr::SE_AllowSideEffects);
1019       if (Result.Val.isInt())
1020         ConstantCondValue = Result.Val.getInt();
1021       assert(!HasConstantCond ||
1022              (ConstantCondValue.getBitWidth() == CondWidth &&
1023               ConstantCondValue.isSigned() == CondIsSigned));
1024     }
1025     bool ShouldCheckConstantCond = HasConstantCond;
1026 
1027     // Sort all the scalar case values so we can easily detect duplicates.
1028     llvm::stable_sort(CaseVals, CmpCaseVals);
1029 
1030     if (!CaseVals.empty()) {
1031       for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
1032         if (ShouldCheckConstantCond &&
1033             CaseVals[i].first == ConstantCondValue)
1034           ShouldCheckConstantCond = false;
1035 
1036         if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
1037           // If we have a duplicate, report it.
1038           // First, determine if either case value has a name
1039           StringRef PrevString, CurrString;
1040           Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts();
1041           Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts();
1042           if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(PrevCase)) {
1043             PrevString = DeclRef->getDecl()->getName();
1044           }
1045           if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(CurrCase)) {
1046             CurrString = DeclRef->getDecl()->getName();
1047           }
1048           SmallString<16> CaseValStr;
1049           CaseVals[i-1].first.toString(CaseValStr);
1050 
1051           if (PrevString == CurrString)
1052             Diag(CaseVals[i].second->getLHS()->getBeginLoc(),
1053                  diag::err_duplicate_case)
1054                 << (PrevString.empty() ? StringRef(CaseValStr) : PrevString);
1055           else
1056             Diag(CaseVals[i].second->getLHS()->getBeginLoc(),
1057                  diag::err_duplicate_case_differing_expr)
1058                 << (PrevString.empty() ? StringRef(CaseValStr) : PrevString)
1059                 << (CurrString.empty() ? StringRef(CaseValStr) : CurrString)
1060                 << CaseValStr;
1061 
1062           Diag(CaseVals[i - 1].second->getLHS()->getBeginLoc(),
1063                diag::note_duplicate_case_prev);
1064           // FIXME: We really want to remove the bogus case stmt from the
1065           // substmt, but we have no way to do this right now.
1066           CaseListIsErroneous = true;
1067         }
1068       }
1069     }
1070 
1071     // Detect duplicate case ranges, which usually don't exist at all in
1072     // the first place.
1073     if (!CaseRanges.empty()) {
1074       // Sort all the case ranges by their low value so we can easily detect
1075       // overlaps between ranges.
1076       llvm::stable_sort(CaseRanges);
1077 
1078       // Scan the ranges, computing the high values and removing empty ranges.
1079       std::vector<llvm::APSInt> HiVals;
1080       for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1081         llvm::APSInt &LoVal = CaseRanges[i].first;
1082         CaseStmt *CR = CaseRanges[i].second;
1083         Expr *Hi = CR->getRHS();
1084 
1085         const Expr *HiBeforePromotion = Hi;
1086         GetTypeBeforeIntegralPromotion(HiBeforePromotion);
1087         llvm::APSInt HiVal = HiBeforePromotion->EvaluateKnownConstInt(Context);
1088 
1089         // Check the unconverted value is within the range of possible values of
1090         // the switch expression.
1091         checkCaseValue(*this, Hi->getBeginLoc(), HiVal,
1092                        CondWidthBeforePromotion, CondIsSignedBeforePromotion);
1093 
1094         // Convert the value to the same width/sign as the condition.
1095         AdjustAPSInt(HiVal, CondWidth, CondIsSigned);
1096 
1097         // If the low value is bigger than the high value, the case is empty.
1098         if (LoVal > HiVal) {
1099           Diag(CR->getLHS()->getBeginLoc(), diag::warn_case_empty_range)
1100               << SourceRange(CR->getLHS()->getBeginLoc(), Hi->getEndLoc());
1101           CaseRanges.erase(CaseRanges.begin()+i);
1102           --i;
1103           --e;
1104           continue;
1105         }
1106 
1107         if (ShouldCheckConstantCond &&
1108             LoVal <= ConstantCondValue &&
1109             ConstantCondValue <= HiVal)
1110           ShouldCheckConstantCond = false;
1111 
1112         HiVals.push_back(HiVal);
1113       }
1114 
1115       // Rescan the ranges, looking for overlap with singleton values and other
1116       // ranges.  Since the range list is sorted, we only need to compare case
1117       // ranges with their neighbors.
1118       for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1119         llvm::APSInt &CRLo = CaseRanges[i].first;
1120         llvm::APSInt &CRHi = HiVals[i];
1121         CaseStmt *CR = CaseRanges[i].second;
1122 
1123         // Check to see whether the case range overlaps with any
1124         // singleton cases.
1125         CaseStmt *OverlapStmt = nullptr;
1126         llvm::APSInt OverlapVal(32);
1127 
1128         // Find the smallest value >= the lower bound.  If I is in the
1129         // case range, then we have overlap.
1130         CaseValsTy::iterator I =
1131             llvm::lower_bound(CaseVals, CRLo, CaseCompareFunctor());
1132         if (I != CaseVals.end() && I->first < CRHi) {
1133           OverlapVal  = I->first;   // Found overlap with scalar.
1134           OverlapStmt = I->second;
1135         }
1136 
1137         // Find the smallest value bigger than the upper bound.
1138         I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
1139         if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
1140           OverlapVal  = (I-1)->first;      // Found overlap with scalar.
1141           OverlapStmt = (I-1)->second;
1142         }
1143 
1144         // Check to see if this case stmt overlaps with the subsequent
1145         // case range.
1146         if (i && CRLo <= HiVals[i-1]) {
1147           OverlapVal  = HiVals[i-1];       // Found overlap with range.
1148           OverlapStmt = CaseRanges[i-1].second;
1149         }
1150 
1151         if (OverlapStmt) {
1152           // If we have a duplicate, report it.
1153           Diag(CR->getLHS()->getBeginLoc(), diag::err_duplicate_case)
1154               << OverlapVal.toString(10);
1155           Diag(OverlapStmt->getLHS()->getBeginLoc(),
1156                diag::note_duplicate_case_prev);
1157           // FIXME: We really want to remove the bogus case stmt from the
1158           // substmt, but we have no way to do this right now.
1159           CaseListIsErroneous = true;
1160         }
1161       }
1162     }
1163 
1164     // Complain if we have a constant condition and we didn't find a match.
1165     if (!CaseListIsErroneous && !CaseListIsIncomplete &&
1166         ShouldCheckConstantCond) {
1167       // TODO: it would be nice if we printed enums as enums, chars as
1168       // chars, etc.
1169       Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
1170         << ConstantCondValue.toString(10)
1171         << CondExpr->getSourceRange();
1172     }
1173 
1174     // Check to see if switch is over an Enum and handles all of its
1175     // values.  We only issue a warning if there is not 'default:', but
1176     // we still do the analysis to preserve this information in the AST
1177     // (which can be used by flow-based analyes).
1178     //
1179     const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
1180 
1181     // If switch has default case, then ignore it.
1182     if (!CaseListIsErroneous && !CaseListIsIncomplete && !HasConstantCond &&
1183         ET && ET->getDecl()->isCompleteDefinition()) {
1184       const EnumDecl *ED = ET->getDecl();
1185       EnumValsTy EnumVals;
1186 
1187       // Gather all enum values, set their type and sort them,
1188       // allowing easier comparison with CaseVals.
1189       for (auto *EDI : ED->enumerators()) {
1190         llvm::APSInt Val = EDI->getInitVal();
1191         AdjustAPSInt(Val, CondWidth, CondIsSigned);
1192         EnumVals.push_back(std::make_pair(Val, EDI));
1193       }
1194       llvm::stable_sort(EnumVals, CmpEnumVals);
1195       auto EI = EnumVals.begin(), EIEnd =
1196         std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1197 
1198       // See which case values aren't in enum.
1199       for (CaseValsTy::const_iterator CI = CaseVals.begin();
1200           CI != CaseVals.end(); CI++) {
1201         Expr *CaseExpr = CI->second->getLHS();
1202         if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1203                                               CI->first))
1204           Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1205             << CondTypeBeforePromotion;
1206       }
1207 
1208       // See which of case ranges aren't in enum
1209       EI = EnumVals.begin();
1210       for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
1211           RI != CaseRanges.end(); RI++) {
1212         Expr *CaseExpr = RI->second->getLHS();
1213         if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1214                                               RI->first))
1215           Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1216             << CondTypeBeforePromotion;
1217 
1218         llvm::APSInt Hi =
1219           RI->second->getRHS()->EvaluateKnownConstInt(Context);
1220         AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1221 
1222         CaseExpr = RI->second->getRHS();
1223         if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1224                                               Hi))
1225           Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1226             << CondTypeBeforePromotion;
1227       }
1228 
1229       // Check which enum vals aren't in switch
1230       auto CI = CaseVals.begin();
1231       auto RI = CaseRanges.begin();
1232       bool hasCasesNotInSwitch = false;
1233 
1234       SmallVector<DeclarationName,8> UnhandledNames;
1235 
1236       for (EI = EnumVals.begin(); EI != EIEnd; EI++) {
1237         // Don't warn about omitted unavailable EnumConstantDecls.
1238         switch (EI->second->getAvailability()) {
1239         case AR_Deprecated:
1240           // Omitting a deprecated constant is ok; it should never materialize.
1241         case AR_Unavailable:
1242           continue;
1243 
1244         case AR_NotYetIntroduced:
1245           // Partially available enum constants should be present. Note that we
1246           // suppress -Wunguarded-availability diagnostics for such uses.
1247         case AR_Available:
1248           break;
1249         }
1250 
1251         if (EI->second->hasAttr<UnusedAttr>())
1252           continue;
1253 
1254         // Drop unneeded case values
1255         while (CI != CaseVals.end() && CI->first < EI->first)
1256           CI++;
1257 
1258         if (CI != CaseVals.end() && CI->first == EI->first)
1259           continue;
1260 
1261         // Drop unneeded case ranges
1262         for (; RI != CaseRanges.end(); RI++) {
1263           llvm::APSInt Hi =
1264             RI->second->getRHS()->EvaluateKnownConstInt(Context);
1265           AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1266           if (EI->first <= Hi)
1267             break;
1268         }
1269 
1270         if (RI == CaseRanges.end() || EI->first < RI->first) {
1271           hasCasesNotInSwitch = true;
1272           UnhandledNames.push_back(EI->second->getDeclName());
1273         }
1274       }
1275 
1276       if (TheDefaultStmt && UnhandledNames.empty() && ED->isClosedNonFlag())
1277         Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
1278 
1279       // Produce a nice diagnostic if multiple values aren't handled.
1280       if (!UnhandledNames.empty()) {
1281         auto DB = Diag(CondExpr->getExprLoc(), TheDefaultStmt
1282                                                    ? diag::warn_def_missing_case
1283                                                    : diag::warn_missing_case)
1284                   << (int)UnhandledNames.size();
1285 
1286         for (size_t I = 0, E = std::min(UnhandledNames.size(), (size_t)3);
1287              I != E; ++I)
1288           DB << UnhandledNames[I];
1289       }
1290 
1291       if (!hasCasesNotInSwitch)
1292         SS->setAllEnumCasesCovered();
1293     }
1294   }
1295 
1296   if (BodyStmt)
1297     DiagnoseEmptyStmtBody(CondExpr->getEndLoc(), BodyStmt,
1298                           diag::warn_empty_switch_body);
1299 
1300   // FIXME: If the case list was broken is some way, we don't have a good system
1301   // to patch it up.  Instead, just return the whole substmt as broken.
1302   if (CaseListIsErroneous)
1303     return StmtError();
1304 
1305   return SS;
1306 }
1307 
1308 void
1309 Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
1310                              Expr *SrcExpr) {
1311   if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc()))
1312     return;
1313 
1314   if (const EnumType *ET = DstType->getAs<EnumType>())
1315     if (!Context.hasSameUnqualifiedType(SrcType, DstType) &&
1316         SrcType->isIntegerType()) {
1317       if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
1318           SrcExpr->isIntegerConstantExpr(Context)) {
1319         // Get the bitwidth of the enum value before promotions.
1320         unsigned DstWidth = Context.getIntWidth(DstType);
1321         bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
1322 
1323         llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
1324         AdjustAPSInt(RhsVal, DstWidth, DstIsSigned);
1325         const EnumDecl *ED = ET->getDecl();
1326 
1327         if (!ED->isClosed())
1328           return;
1329 
1330         if (ED->hasAttr<FlagEnumAttr>()) {
1331           if (!IsValueInFlagEnum(ED, RhsVal, true))
1332             Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1333               << DstType.getUnqualifiedType();
1334         } else {
1335           typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl *>, 64>
1336               EnumValsTy;
1337           EnumValsTy EnumVals;
1338 
1339           // Gather all enum values, set their type and sort them,
1340           // allowing easier comparison with rhs constant.
1341           for (auto *EDI : ED->enumerators()) {
1342             llvm::APSInt Val = EDI->getInitVal();
1343             AdjustAPSInt(Val, DstWidth, DstIsSigned);
1344             EnumVals.push_back(std::make_pair(Val, EDI));
1345           }
1346           if (EnumVals.empty())
1347             return;
1348           llvm::stable_sort(EnumVals, CmpEnumVals);
1349           EnumValsTy::iterator EIend =
1350               std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1351 
1352           // See which values aren't in the enum.
1353           EnumValsTy::const_iterator EI = EnumVals.begin();
1354           while (EI != EIend && EI->first < RhsVal)
1355             EI++;
1356           if (EI == EIend || EI->first != RhsVal) {
1357             Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1358                 << DstType.getUnqualifiedType();
1359           }
1360         }
1361       }
1362     }
1363 }
1364 
1365 StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc,
1366                                 SourceLocation LParenLoc, ConditionResult Cond,
1367                                 SourceLocation RParenLoc, Stmt *Body) {
1368   if (Cond.isInvalid())
1369     return StmtError();
1370 
1371   auto CondVal = Cond.get();
1372   CheckBreakContinueBinding(CondVal.second);
1373 
1374   if (CondVal.second &&
1375       !Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc()))
1376     CommaVisitor(*this).Visit(CondVal.second);
1377 
1378   if (isa<NullStmt>(Body))
1379     getCurCompoundScope().setHasEmptyLoopBodies();
1380 
1381   return WhileStmt::Create(Context, CondVal.first, CondVal.second, Body,
1382                            WhileLoc, LParenLoc, RParenLoc);
1383 }
1384 
1385 StmtResult
1386 Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
1387                   SourceLocation WhileLoc, SourceLocation CondLParen,
1388                   Expr *Cond, SourceLocation CondRParen) {
1389   assert(Cond && "ActOnDoStmt(): missing expression");
1390 
1391   CheckBreakContinueBinding(Cond);
1392   ExprResult CondResult = CheckBooleanCondition(DoLoc, Cond);
1393   if (CondResult.isInvalid())
1394     return StmtError();
1395   Cond = CondResult.get();
1396 
1397   CondResult = ActOnFinishFullExpr(Cond, DoLoc, /*DiscardedValue*/ false);
1398   if (CondResult.isInvalid())
1399     return StmtError();
1400   Cond = CondResult.get();
1401 
1402   // Only call the CommaVisitor for C89 due to differences in scope flags.
1403   if (Cond && !getLangOpts().C99 && !getLangOpts().CPlusPlus &&
1404       !Diags.isIgnored(diag::warn_comma_operator, Cond->getExprLoc()))
1405     CommaVisitor(*this).Visit(Cond);
1406 
1407   return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen);
1408 }
1409 
1410 namespace {
1411   // Use SetVector since the diagnostic cares about the ordering of the Decl's.
1412   using DeclSetVector =
1413       llvm::SetVector<VarDecl *, llvm::SmallVector<VarDecl *, 8>,
1414                       llvm::SmallPtrSet<VarDecl *, 8>>;
1415 
1416   // This visitor will traverse a conditional statement and store all
1417   // the evaluated decls into a vector.  Simple is set to true if none
1418   // of the excluded constructs are used.
1419   class DeclExtractor : public EvaluatedExprVisitor<DeclExtractor> {
1420     DeclSetVector &Decls;
1421     SmallVectorImpl<SourceRange> &Ranges;
1422     bool Simple;
1423   public:
1424     typedef EvaluatedExprVisitor<DeclExtractor> Inherited;
1425 
1426     DeclExtractor(Sema &S, DeclSetVector &Decls,
1427                   SmallVectorImpl<SourceRange> &Ranges) :
1428         Inherited(S.Context),
1429         Decls(Decls),
1430         Ranges(Ranges),
1431         Simple(true) {}
1432 
1433     bool isSimple() { return Simple; }
1434 
1435     // Replaces the method in EvaluatedExprVisitor.
1436     void VisitMemberExpr(MemberExpr* E) {
1437       Simple = false;
1438     }
1439 
1440     // Any Stmt not explicitly listed will cause the condition to be marked
1441     // complex.
1442     void VisitStmt(Stmt *S) { Simple = false; }
1443 
1444     void VisitBinaryOperator(BinaryOperator *E) {
1445       Visit(E->getLHS());
1446       Visit(E->getRHS());
1447     }
1448 
1449     void VisitCastExpr(CastExpr *E) {
1450       Visit(E->getSubExpr());
1451     }
1452 
1453     void VisitUnaryOperator(UnaryOperator *E) {
1454       // Skip checking conditionals with derefernces.
1455       if (E->getOpcode() == UO_Deref)
1456         Simple = false;
1457       else
1458         Visit(E->getSubExpr());
1459     }
1460 
1461     void VisitConditionalOperator(ConditionalOperator *E) {
1462       Visit(E->getCond());
1463       Visit(E->getTrueExpr());
1464       Visit(E->getFalseExpr());
1465     }
1466 
1467     void VisitParenExpr(ParenExpr *E) {
1468       Visit(E->getSubExpr());
1469     }
1470 
1471     void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
1472       Visit(E->getOpaqueValue()->getSourceExpr());
1473       Visit(E->getFalseExpr());
1474     }
1475 
1476     void VisitIntegerLiteral(IntegerLiteral *E) { }
1477     void VisitFloatingLiteral(FloatingLiteral *E) { }
1478     void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { }
1479     void VisitCharacterLiteral(CharacterLiteral *E) { }
1480     void VisitGNUNullExpr(GNUNullExpr *E) { }
1481     void VisitImaginaryLiteral(ImaginaryLiteral *E) { }
1482 
1483     void VisitDeclRefExpr(DeclRefExpr *E) {
1484       VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
1485       if (!VD) {
1486         // Don't allow unhandled Decl types.
1487         Simple = false;
1488         return;
1489       }
1490 
1491       Ranges.push_back(E->getSourceRange());
1492 
1493       Decls.insert(VD);
1494     }
1495 
1496   }; // end class DeclExtractor
1497 
1498   // DeclMatcher checks to see if the decls are used in a non-evaluated
1499   // context.
1500   class DeclMatcher : public EvaluatedExprVisitor<DeclMatcher> {
1501     DeclSetVector &Decls;
1502     bool FoundDecl;
1503 
1504   public:
1505     typedef EvaluatedExprVisitor<DeclMatcher> Inherited;
1506 
1507     DeclMatcher(Sema &S, DeclSetVector &Decls, Stmt *Statement) :
1508         Inherited(S.Context), Decls(Decls), FoundDecl(false) {
1509       if (!Statement) return;
1510 
1511       Visit(Statement);
1512     }
1513 
1514     void VisitReturnStmt(ReturnStmt *S) {
1515       FoundDecl = true;
1516     }
1517 
1518     void VisitBreakStmt(BreakStmt *S) {
1519       FoundDecl = true;
1520     }
1521 
1522     void VisitGotoStmt(GotoStmt *S) {
1523       FoundDecl = true;
1524     }
1525 
1526     void VisitCastExpr(CastExpr *E) {
1527       if (E->getCastKind() == CK_LValueToRValue)
1528         CheckLValueToRValueCast(E->getSubExpr());
1529       else
1530         Visit(E->getSubExpr());
1531     }
1532 
1533     void CheckLValueToRValueCast(Expr *E) {
1534       E = E->IgnoreParenImpCasts();
1535 
1536       if (isa<DeclRefExpr>(E)) {
1537         return;
1538       }
1539 
1540       if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
1541         Visit(CO->getCond());
1542         CheckLValueToRValueCast(CO->getTrueExpr());
1543         CheckLValueToRValueCast(CO->getFalseExpr());
1544         return;
1545       }
1546 
1547       if (BinaryConditionalOperator *BCO =
1548               dyn_cast<BinaryConditionalOperator>(E)) {
1549         CheckLValueToRValueCast(BCO->getOpaqueValue()->getSourceExpr());
1550         CheckLValueToRValueCast(BCO->getFalseExpr());
1551         return;
1552       }
1553 
1554       Visit(E);
1555     }
1556 
1557     void VisitDeclRefExpr(DeclRefExpr *E) {
1558       if (VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
1559         if (Decls.count(VD))
1560           FoundDecl = true;
1561     }
1562 
1563     void VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
1564       // Only need to visit the semantics for POE.
1565       // SyntaticForm doesn't really use the Decal.
1566       for (auto *S : POE->semantics()) {
1567         if (auto *OVE = dyn_cast<OpaqueValueExpr>(S))
1568           // Look past the OVE into the expression it binds.
1569           Visit(OVE->getSourceExpr());
1570         else
1571           Visit(S);
1572       }
1573     }
1574 
1575     bool FoundDeclInUse() { return FoundDecl; }
1576 
1577   };  // end class DeclMatcher
1578 
1579   void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
1580                                         Expr *Third, Stmt *Body) {
1581     // Condition is empty
1582     if (!Second) return;
1583 
1584     if (S.Diags.isIgnored(diag::warn_variables_not_in_loop_body,
1585                           Second->getBeginLoc()))
1586       return;
1587 
1588     PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body);
1589     DeclSetVector Decls;
1590     SmallVector<SourceRange, 10> Ranges;
1591     DeclExtractor DE(S, Decls, Ranges);
1592     DE.Visit(Second);
1593 
1594     // Don't analyze complex conditionals.
1595     if (!DE.isSimple()) return;
1596 
1597     // No decls found.
1598     if (Decls.size() == 0) return;
1599 
1600     // Don't warn on volatile, static, or global variables.
1601     for (auto *VD : Decls)
1602       if (VD->getType().isVolatileQualified() || VD->hasGlobalStorage())
1603         return;
1604 
1605     if (DeclMatcher(S, Decls, Second).FoundDeclInUse() ||
1606         DeclMatcher(S, Decls, Third).FoundDeclInUse() ||
1607         DeclMatcher(S, Decls, Body).FoundDeclInUse())
1608       return;
1609 
1610     // Load decl names into diagnostic.
1611     if (Decls.size() > 4) {
1612       PDiag << 0;
1613     } else {
1614       PDiag << (unsigned)Decls.size();
1615       for (auto *VD : Decls)
1616         PDiag << VD->getDeclName();
1617     }
1618 
1619     for (auto Range : Ranges)
1620       PDiag << Range;
1621 
1622     S.Diag(Ranges.begin()->getBegin(), PDiag);
1623   }
1624 
1625   // If Statement is an incemement or decrement, return true and sets the
1626   // variables Increment and DRE.
1627   bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment,
1628                             DeclRefExpr *&DRE) {
1629     if (auto Cleanups = dyn_cast<ExprWithCleanups>(Statement))
1630       if (!Cleanups->cleanupsHaveSideEffects())
1631         Statement = Cleanups->getSubExpr();
1632 
1633     if (UnaryOperator *UO = dyn_cast<UnaryOperator>(Statement)) {
1634       switch (UO->getOpcode()) {
1635         default: return false;
1636         case UO_PostInc:
1637         case UO_PreInc:
1638           Increment = true;
1639           break;
1640         case UO_PostDec:
1641         case UO_PreDec:
1642           Increment = false;
1643           break;
1644       }
1645       DRE = dyn_cast<DeclRefExpr>(UO->getSubExpr());
1646       return DRE;
1647     }
1648 
1649     if (CXXOperatorCallExpr *Call = dyn_cast<CXXOperatorCallExpr>(Statement)) {
1650       FunctionDecl *FD = Call->getDirectCallee();
1651       if (!FD || !FD->isOverloadedOperator()) return false;
1652       switch (FD->getOverloadedOperator()) {
1653         default: return false;
1654         case OO_PlusPlus:
1655           Increment = true;
1656           break;
1657         case OO_MinusMinus:
1658           Increment = false;
1659           break;
1660       }
1661       DRE = dyn_cast<DeclRefExpr>(Call->getArg(0));
1662       return DRE;
1663     }
1664 
1665     return false;
1666   }
1667 
1668   // A visitor to determine if a continue or break statement is a
1669   // subexpression.
1670   class BreakContinueFinder : public ConstEvaluatedExprVisitor<BreakContinueFinder> {
1671     SourceLocation BreakLoc;
1672     SourceLocation ContinueLoc;
1673     bool InSwitch = false;
1674 
1675   public:
1676     BreakContinueFinder(Sema &S, const Stmt* Body) :
1677         Inherited(S.Context) {
1678       Visit(Body);
1679     }
1680 
1681     typedef ConstEvaluatedExprVisitor<BreakContinueFinder> Inherited;
1682 
1683     void VisitContinueStmt(const ContinueStmt* E) {
1684       ContinueLoc = E->getContinueLoc();
1685     }
1686 
1687     void VisitBreakStmt(const BreakStmt* E) {
1688       if (!InSwitch)
1689         BreakLoc = E->getBreakLoc();
1690     }
1691 
1692     void VisitSwitchStmt(const SwitchStmt* S) {
1693       if (const Stmt *Init = S->getInit())
1694         Visit(Init);
1695       if (const Stmt *CondVar = S->getConditionVariableDeclStmt())
1696         Visit(CondVar);
1697       if (const Stmt *Cond = S->getCond())
1698         Visit(Cond);
1699 
1700       // Don't return break statements from the body of a switch.
1701       InSwitch = true;
1702       if (const Stmt *Body = S->getBody())
1703         Visit(Body);
1704       InSwitch = false;
1705     }
1706 
1707     void VisitForStmt(const ForStmt *S) {
1708       // Only visit the init statement of a for loop; the body
1709       // has a different break/continue scope.
1710       if (const Stmt *Init = S->getInit())
1711         Visit(Init);
1712     }
1713 
1714     void VisitWhileStmt(const WhileStmt *) {
1715       // Do nothing; the children of a while loop have a different
1716       // break/continue scope.
1717     }
1718 
1719     void VisitDoStmt(const DoStmt *) {
1720       // Do nothing; the children of a while loop have a different
1721       // break/continue scope.
1722     }
1723 
1724     void VisitCXXForRangeStmt(const CXXForRangeStmt *S) {
1725       // Only visit the initialization of a for loop; the body
1726       // has a different break/continue scope.
1727       if (const Stmt *Init = S->getInit())
1728         Visit(Init);
1729       if (const Stmt *Range = S->getRangeStmt())
1730         Visit(Range);
1731       if (const Stmt *Begin = S->getBeginStmt())
1732         Visit(Begin);
1733       if (const Stmt *End = S->getEndStmt())
1734         Visit(End);
1735     }
1736 
1737     void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S) {
1738       // Only visit the initialization of a for loop; the body
1739       // has a different break/continue scope.
1740       if (const Stmt *Element = S->getElement())
1741         Visit(Element);
1742       if (const Stmt *Collection = S->getCollection())
1743         Visit(Collection);
1744     }
1745 
1746     bool ContinueFound() { return ContinueLoc.isValid(); }
1747     bool BreakFound() { return BreakLoc.isValid(); }
1748     SourceLocation GetContinueLoc() { return ContinueLoc; }
1749     SourceLocation GetBreakLoc() { return BreakLoc; }
1750 
1751   };  // end class BreakContinueFinder
1752 
1753   // Emit a warning when a loop increment/decrement appears twice per loop
1754   // iteration.  The conditions which trigger this warning are:
1755   // 1) The last statement in the loop body and the third expression in the
1756   //    for loop are both increment or both decrement of the same variable
1757   // 2) No continue statements in the loop body.
1758   void CheckForRedundantIteration(Sema &S, Expr *Third, Stmt *Body) {
1759     // Return when there is nothing to check.
1760     if (!Body || !Third) return;
1761 
1762     if (S.Diags.isIgnored(diag::warn_redundant_loop_iteration,
1763                           Third->getBeginLoc()))
1764       return;
1765 
1766     // Get the last statement from the loop body.
1767     CompoundStmt *CS = dyn_cast<CompoundStmt>(Body);
1768     if (!CS || CS->body_empty()) return;
1769     Stmt *LastStmt = CS->body_back();
1770     if (!LastStmt) return;
1771 
1772     bool LoopIncrement, LastIncrement;
1773     DeclRefExpr *LoopDRE, *LastDRE;
1774 
1775     if (!ProcessIterationStmt(S, Third, LoopIncrement, LoopDRE)) return;
1776     if (!ProcessIterationStmt(S, LastStmt, LastIncrement, LastDRE)) return;
1777 
1778     // Check that the two statements are both increments or both decrements
1779     // on the same variable.
1780     if (LoopIncrement != LastIncrement ||
1781         LoopDRE->getDecl() != LastDRE->getDecl()) return;
1782 
1783     if (BreakContinueFinder(S, Body).ContinueFound()) return;
1784 
1785     S.Diag(LastDRE->getLocation(), diag::warn_redundant_loop_iteration)
1786          << LastDRE->getDecl() << LastIncrement;
1787     S.Diag(LoopDRE->getLocation(), diag::note_loop_iteration_here)
1788          << LoopIncrement;
1789   }
1790 
1791 } // end namespace
1792 
1793 
1794 void Sema::CheckBreakContinueBinding(Expr *E) {
1795   if (!E || getLangOpts().CPlusPlus)
1796     return;
1797   BreakContinueFinder BCFinder(*this, E);
1798   Scope *BreakParent = CurScope->getBreakParent();
1799   if (BCFinder.BreakFound() && BreakParent) {
1800     if (BreakParent->getFlags() & Scope::SwitchScope) {
1801       Diag(BCFinder.GetBreakLoc(), diag::warn_break_binds_to_switch);
1802     } else {
1803       Diag(BCFinder.GetBreakLoc(), diag::warn_loop_ctrl_binds_to_inner)
1804           << "break";
1805     }
1806   } else if (BCFinder.ContinueFound() && CurScope->getContinueParent()) {
1807     Diag(BCFinder.GetContinueLoc(), diag::warn_loop_ctrl_binds_to_inner)
1808         << "continue";
1809   }
1810 }
1811 
1812 StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
1813                               Stmt *First, ConditionResult Second,
1814                               FullExprArg third, SourceLocation RParenLoc,
1815                               Stmt *Body) {
1816   if (Second.isInvalid())
1817     return StmtError();
1818 
1819   if (!getLangOpts().CPlusPlus) {
1820     if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
1821       // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1822       // declare identifiers for objects having storage class 'auto' or
1823       // 'register'.
1824       const Decl *NonVarSeen = nullptr;
1825       bool VarDeclSeen = false;
1826       for (auto *DI : DS->decls()) {
1827         if (VarDecl *VD = dyn_cast<VarDecl>(DI)) {
1828           VarDeclSeen = true;
1829           if (VD->isLocalVarDecl() && !VD->hasLocalStorage()) {
1830             Diag(DI->getLocation(), diag::err_non_local_variable_decl_in_for);
1831             DI->setInvalidDecl();
1832           }
1833         } else if (!NonVarSeen) {
1834           // Keep track of the first non-variable declaration we saw so that
1835           // we can diagnose if we don't see any variable declarations. This
1836           // covers a case like declaring a typedef, function, or structure
1837           // type rather than a variable.
1838           NonVarSeen = DI;
1839         }
1840       }
1841       // Diagnose if we saw a non-variable declaration but no variable
1842       // declarations.
1843       if (NonVarSeen && !VarDeclSeen)
1844         Diag(NonVarSeen->getLocation(), diag::err_non_variable_decl_in_for);
1845     }
1846   }
1847 
1848   CheckBreakContinueBinding(Second.get().second);
1849   CheckBreakContinueBinding(third.get());
1850 
1851   if (!Second.get().first)
1852     CheckForLoopConditionalStatement(*this, Second.get().second, third.get(),
1853                                      Body);
1854   CheckForRedundantIteration(*this, third.get(), Body);
1855 
1856   if (Second.get().second &&
1857       !Diags.isIgnored(diag::warn_comma_operator,
1858                        Second.get().second->getExprLoc()))
1859     CommaVisitor(*this).Visit(Second.get().second);
1860 
1861   Expr *Third  = third.release().getAs<Expr>();
1862   if (isa<NullStmt>(Body))
1863     getCurCompoundScope().setHasEmptyLoopBodies();
1864 
1865   return new (Context)
1866       ForStmt(Context, First, Second.get().second, Second.get().first, Third,
1867               Body, ForLoc, LParenLoc, RParenLoc);
1868 }
1869 
1870 /// In an Objective C collection iteration statement:
1871 ///   for (x in y)
1872 /// x can be an arbitrary l-value expression.  Bind it up as a
1873 /// full-expression.
1874 StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
1875   // Reduce placeholder expressions here.  Note that this rejects the
1876   // use of pseudo-object l-values in this position.
1877   ExprResult result = CheckPlaceholderExpr(E);
1878   if (result.isInvalid()) return StmtError();
1879   E = result.get();
1880 
1881   ExprResult FullExpr = ActOnFinishFullExpr(E, /*DiscardedValue*/ false);
1882   if (FullExpr.isInvalid())
1883     return StmtError();
1884   return StmtResult(static_cast<Stmt*>(FullExpr.get()));
1885 }
1886 
1887 ExprResult
1888 Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) {
1889   if (!collection)
1890     return ExprError();
1891 
1892   ExprResult result = CorrectDelayedTyposInExpr(collection);
1893   if (!result.isUsable())
1894     return ExprError();
1895   collection = result.get();
1896 
1897   // Bail out early if we've got a type-dependent expression.
1898   if (collection->isTypeDependent()) return collection;
1899 
1900   // Perform normal l-value conversion.
1901   result = DefaultFunctionArrayLvalueConversion(collection);
1902   if (result.isInvalid())
1903     return ExprError();
1904   collection = result.get();
1905 
1906   // The operand needs to have object-pointer type.
1907   // TODO: should we do a contextual conversion?
1908   const ObjCObjectPointerType *pointerType =
1909     collection->getType()->getAs<ObjCObjectPointerType>();
1910   if (!pointerType)
1911     return Diag(forLoc, diag::err_collection_expr_type)
1912              << collection->getType() << collection->getSourceRange();
1913 
1914   // Check that the operand provides
1915   //   - countByEnumeratingWithState:objects:count:
1916   const ObjCObjectType *objectType = pointerType->getObjectType();
1917   ObjCInterfaceDecl *iface = objectType->getInterface();
1918 
1919   // If we have a forward-declared type, we can't do this check.
1920   // Under ARC, it is an error not to have a forward-declared class.
1921   if (iface &&
1922       (getLangOpts().ObjCAutoRefCount
1923            ? RequireCompleteType(forLoc, QualType(objectType, 0),
1924                                  diag::err_arc_collection_forward, collection)
1925            : !isCompleteType(forLoc, QualType(objectType, 0)))) {
1926     // Otherwise, if we have any useful type information, check that
1927     // the type declares the appropriate method.
1928   } else if (iface || !objectType->qual_empty()) {
1929     IdentifierInfo *selectorIdents[] = {
1930       &Context.Idents.get("countByEnumeratingWithState"),
1931       &Context.Idents.get("objects"),
1932       &Context.Idents.get("count")
1933     };
1934     Selector selector = Context.Selectors.getSelector(3, &selectorIdents[0]);
1935 
1936     ObjCMethodDecl *method = nullptr;
1937 
1938     // If there's an interface, look in both the public and private APIs.
1939     if (iface) {
1940       method = iface->lookupInstanceMethod(selector);
1941       if (!method) method = iface->lookupPrivateMethod(selector);
1942     }
1943 
1944     // Also check protocol qualifiers.
1945     if (!method)
1946       method = LookupMethodInQualifiedType(selector, pointerType,
1947                                            /*instance*/ true);
1948 
1949     // If we didn't find it anywhere, give up.
1950     if (!method) {
1951       Diag(forLoc, diag::warn_collection_expr_type)
1952         << collection->getType() << selector << collection->getSourceRange();
1953     }
1954 
1955     // TODO: check for an incompatible signature?
1956   }
1957 
1958   // Wrap up any cleanups in the expression.
1959   return collection;
1960 }
1961 
1962 StmtResult
1963 Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
1964                                  Stmt *First, Expr *collection,
1965                                  SourceLocation RParenLoc) {
1966   setFunctionHasBranchProtectedScope();
1967 
1968   ExprResult CollectionExprResult =
1969     CheckObjCForCollectionOperand(ForLoc, collection);
1970 
1971   if (First) {
1972     QualType FirstType;
1973     if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
1974       if (!DS->isSingleDecl())
1975         return StmtError(Diag((*DS->decl_begin())->getLocation(),
1976                          diag::err_toomany_element_decls));
1977 
1978       VarDecl *D = dyn_cast<VarDecl>(DS->getSingleDecl());
1979       if (!D || D->isInvalidDecl())
1980         return StmtError();
1981 
1982       FirstType = D->getType();
1983       // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1984       // declare identifiers for objects having storage class 'auto' or
1985       // 'register'.
1986       if (!D->hasLocalStorage())
1987         return StmtError(Diag(D->getLocation(),
1988                               diag::err_non_local_variable_decl_in_for));
1989 
1990       // If the type contained 'auto', deduce the 'auto' to 'id'.
1991       if (FirstType->getContainedAutoType()) {
1992         OpaqueValueExpr OpaqueId(D->getLocation(), Context.getObjCIdType(),
1993                                  VK_RValue);
1994         Expr *DeducedInit = &OpaqueId;
1995         if (DeduceAutoType(D->getTypeSourceInfo(), DeducedInit, FirstType) ==
1996                 DAR_Failed)
1997           DiagnoseAutoDeductionFailure(D, DeducedInit);
1998         if (FirstType.isNull()) {
1999           D->setInvalidDecl();
2000           return StmtError();
2001         }
2002 
2003         D->setType(FirstType);
2004 
2005         if (!inTemplateInstantiation()) {
2006           SourceLocation Loc =
2007               D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
2008           Diag(Loc, diag::warn_auto_var_is_id)
2009             << D->getDeclName();
2010         }
2011       }
2012 
2013     } else {
2014       Expr *FirstE = cast<Expr>(First);
2015       if (!FirstE->isTypeDependent() && !FirstE->isLValue())
2016         return StmtError(
2017             Diag(First->getBeginLoc(), diag::err_selector_element_not_lvalue)
2018             << First->getSourceRange());
2019 
2020       FirstType = static_cast<Expr*>(First)->getType();
2021       if (FirstType.isConstQualified())
2022         Diag(ForLoc, diag::err_selector_element_const_type)
2023           << FirstType << First->getSourceRange();
2024     }
2025     if (!FirstType->isDependentType() &&
2026         !FirstType->isObjCObjectPointerType() &&
2027         !FirstType->isBlockPointerType())
2028         return StmtError(Diag(ForLoc, diag::err_selector_element_type)
2029                            << FirstType << First->getSourceRange());
2030   }
2031 
2032   if (CollectionExprResult.isInvalid())
2033     return StmtError();
2034 
2035   CollectionExprResult =
2036       ActOnFinishFullExpr(CollectionExprResult.get(), /*DiscardedValue*/ false);
2037   if (CollectionExprResult.isInvalid())
2038     return StmtError();
2039 
2040   return new (Context) ObjCForCollectionStmt(First, CollectionExprResult.get(),
2041                                              nullptr, ForLoc, RParenLoc);
2042 }
2043 
2044 /// Finish building a variable declaration for a for-range statement.
2045 /// \return true if an error occurs.
2046 static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
2047                                   SourceLocation Loc, int DiagID) {
2048   if (Decl->getType()->isUndeducedType()) {
2049     ExprResult Res = SemaRef.CorrectDelayedTyposInExpr(Init);
2050     if (!Res.isUsable()) {
2051       Decl->setInvalidDecl();
2052       return true;
2053     }
2054     Init = Res.get();
2055   }
2056 
2057   // Deduce the type for the iterator variable now rather than leaving it to
2058   // AddInitializerToDecl, so we can produce a more suitable diagnostic.
2059   QualType InitType;
2060   if ((!isa<InitListExpr>(Init) && Init->getType()->isVoidType()) ||
2061       SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitType) ==
2062           Sema::DAR_Failed)
2063     SemaRef.Diag(Loc, DiagID) << Init->getType();
2064   if (InitType.isNull()) {
2065     Decl->setInvalidDecl();
2066     return true;
2067   }
2068   Decl->setType(InitType);
2069 
2070   // In ARC, infer lifetime.
2071   // FIXME: ARC may want to turn this into 'const __unsafe_unretained' if
2072   // we're doing the equivalent of fast iteration.
2073   if (SemaRef.getLangOpts().ObjCAutoRefCount &&
2074       SemaRef.inferObjCARCLifetime(Decl))
2075     Decl->setInvalidDecl();
2076 
2077   SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false);
2078   SemaRef.FinalizeDeclaration(Decl);
2079   SemaRef.CurContext->addHiddenDecl(Decl);
2080   return false;
2081 }
2082 
2083 namespace {
2084 // An enum to represent whether something is dealing with a call to begin()
2085 // or a call to end() in a range-based for loop.
2086 enum BeginEndFunction {
2087   BEF_begin,
2088   BEF_end
2089 };
2090 
2091 /// Produce a note indicating which begin/end function was implicitly called
2092 /// by a C++11 for-range statement. This is often not obvious from the code,
2093 /// nor from the diagnostics produced when analysing the implicit expressions
2094 /// required in a for-range statement.
2095 void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
2096                                   BeginEndFunction BEF) {
2097   CallExpr *CE = dyn_cast<CallExpr>(E);
2098   if (!CE)
2099     return;
2100   FunctionDecl *D = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
2101   if (!D)
2102     return;
2103   SourceLocation Loc = D->getLocation();
2104 
2105   std::string Description;
2106   bool IsTemplate = false;
2107   if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) {
2108     Description = SemaRef.getTemplateArgumentBindingsText(
2109       FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs());
2110     IsTemplate = true;
2111   }
2112 
2113   SemaRef.Diag(Loc, diag::note_for_range_begin_end)
2114     << BEF << IsTemplate << Description << E->getType();
2115 }
2116 
2117 /// Build a variable declaration for a for-range statement.
2118 VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
2119                               QualType Type, StringRef Name) {
2120   DeclContext *DC = SemaRef.CurContext;
2121   IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
2122   TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc);
2123   VarDecl *Decl = VarDecl::Create(SemaRef.Context, DC, Loc, Loc, II, Type,
2124                                   TInfo, SC_None);
2125   Decl->setImplicit();
2126   return Decl;
2127 }
2128 
2129 }
2130 
2131 static bool ObjCEnumerationCollection(Expr *Collection) {
2132   return !Collection->isTypeDependent()
2133           && Collection->getType()->getAs<ObjCObjectPointerType>() != nullptr;
2134 }
2135 
2136 /// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement.
2137 ///
2138 /// C++11 [stmt.ranged]:
2139 ///   A range-based for statement is equivalent to
2140 ///
2141 ///   {
2142 ///     auto && __range = range-init;
2143 ///     for ( auto __begin = begin-expr,
2144 ///           __end = end-expr;
2145 ///           __begin != __end;
2146 ///           ++__begin ) {
2147 ///       for-range-declaration = *__begin;
2148 ///       statement
2149 ///     }
2150 ///   }
2151 ///
2152 /// The body of the loop is not available yet, since it cannot be analysed until
2153 /// we have determined the type of the for-range-declaration.
2154 StmtResult Sema::ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc,
2155                                       SourceLocation CoawaitLoc, Stmt *InitStmt,
2156                                       Stmt *First, SourceLocation ColonLoc,
2157                                       Expr *Range, SourceLocation RParenLoc,
2158                                       BuildForRangeKind Kind) {
2159   if (!First)
2160     return StmtError();
2161 
2162   if (Range && ObjCEnumerationCollection(Range)) {
2163     // FIXME: Support init-statements in Objective-C++20 ranged for statement.
2164     if (InitStmt)
2165       return Diag(InitStmt->getBeginLoc(), diag::err_objc_for_range_init_stmt)
2166                  << InitStmt->getSourceRange();
2167     return ActOnObjCForCollectionStmt(ForLoc, First, Range, RParenLoc);
2168   }
2169 
2170   DeclStmt *DS = dyn_cast<DeclStmt>(First);
2171   assert(DS && "first part of for range not a decl stmt");
2172 
2173   if (!DS->isSingleDecl()) {
2174     Diag(DS->getBeginLoc(), diag::err_type_defined_in_for_range);
2175     return StmtError();
2176   }
2177 
2178   // This function is responsible for attaching an initializer to LoopVar. We
2179   // must call ActOnInitializerError if we fail to do so.
2180   Decl *LoopVar = DS->getSingleDecl();
2181   if (LoopVar->isInvalidDecl() || !Range ||
2182       DiagnoseUnexpandedParameterPack(Range, UPPC_Expression)) {
2183     ActOnInitializerError(LoopVar);
2184     return StmtError();
2185   }
2186 
2187   // Build the coroutine state immediately and not later during template
2188   // instantiation
2189   if (!CoawaitLoc.isInvalid()) {
2190     if (!ActOnCoroutineBodyStart(S, CoawaitLoc, "co_await")) {
2191       ActOnInitializerError(LoopVar);
2192       return StmtError();
2193     }
2194   }
2195 
2196   // Build  auto && __range = range-init
2197   // Divide by 2, since the variables are in the inner scope (loop body).
2198   const auto DepthStr = std::to_string(S->getDepth() / 2);
2199   SourceLocation RangeLoc = Range->getBeginLoc();
2200   VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc,
2201                                            Context.getAutoRRefDeductType(),
2202                                            std::string("__range") + DepthStr);
2203   if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
2204                             diag::err_for_range_deduction_failure)) {
2205     ActOnInitializerError(LoopVar);
2206     return StmtError();
2207   }
2208 
2209   // Claim the type doesn't contain auto: we've already done the checking.
2210   DeclGroupPtrTy RangeGroup =
2211       BuildDeclaratorGroup(MutableArrayRef<Decl *>((Decl **)&RangeVar, 1));
2212   StmtResult RangeDecl = ActOnDeclStmt(RangeGroup, RangeLoc, RangeLoc);
2213   if (RangeDecl.isInvalid()) {
2214     ActOnInitializerError(LoopVar);
2215     return StmtError();
2216   }
2217 
2218   StmtResult R = BuildCXXForRangeStmt(
2219       ForLoc, CoawaitLoc, InitStmt, ColonLoc, RangeDecl.get(),
2220       /*BeginStmt=*/nullptr, /*EndStmt=*/nullptr,
2221       /*Cond=*/nullptr, /*Inc=*/nullptr, DS, RParenLoc, Kind);
2222   if (R.isInvalid()) {
2223     ActOnInitializerError(LoopVar);
2224     return StmtError();
2225   }
2226 
2227   return R;
2228 }
2229 
2230 /// Create the initialization, compare, and increment steps for
2231 /// the range-based for loop expression.
2232 /// This function does not handle array-based for loops,
2233 /// which are created in Sema::BuildCXXForRangeStmt.
2234 ///
2235 /// \returns a ForRangeStatus indicating success or what kind of error occurred.
2236 /// BeginExpr and EndExpr are set and FRS_Success is returned on success;
2237 /// CandidateSet and BEF are set and some non-success value is returned on
2238 /// failure.
2239 static Sema::ForRangeStatus
2240 BuildNonArrayForRange(Sema &SemaRef, Expr *BeginRange, Expr *EndRange,
2241                       QualType RangeType, VarDecl *BeginVar, VarDecl *EndVar,
2242                       SourceLocation ColonLoc, SourceLocation CoawaitLoc,
2243                       OverloadCandidateSet *CandidateSet, ExprResult *BeginExpr,
2244                       ExprResult *EndExpr, BeginEndFunction *BEF) {
2245   DeclarationNameInfo BeginNameInfo(
2246       &SemaRef.PP.getIdentifierTable().get("begin"), ColonLoc);
2247   DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get("end"),
2248                                   ColonLoc);
2249 
2250   LookupResult BeginMemberLookup(SemaRef, BeginNameInfo,
2251                                  Sema::LookupMemberName);
2252   LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName);
2253 
2254   auto BuildBegin = [&] {
2255     *BEF = BEF_begin;
2256     Sema::ForRangeStatus RangeStatus =
2257         SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, BeginNameInfo,
2258                                           BeginMemberLookup, CandidateSet,
2259                                           BeginRange, BeginExpr);
2260 
2261     if (RangeStatus != Sema::FRS_Success) {
2262       if (RangeStatus == Sema::FRS_DiagnosticIssued)
2263         SemaRef.Diag(BeginRange->getBeginLoc(), diag::note_in_for_range)
2264             << ColonLoc << BEF_begin << BeginRange->getType();
2265       return RangeStatus;
2266     }
2267     if (!CoawaitLoc.isInvalid()) {
2268       // FIXME: getCurScope() should not be used during template instantiation.
2269       // We should pick up the set of unqualified lookup results for operator
2270       // co_await during the initial parse.
2271       *BeginExpr = SemaRef.ActOnCoawaitExpr(SemaRef.getCurScope(), ColonLoc,
2272                                             BeginExpr->get());
2273       if (BeginExpr->isInvalid())
2274         return Sema::FRS_DiagnosticIssued;
2275     }
2276     if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc,
2277                               diag::err_for_range_iter_deduction_failure)) {
2278       NoteForRangeBeginEndFunction(SemaRef, BeginExpr->get(), *BEF);
2279       return Sema::FRS_DiagnosticIssued;
2280     }
2281     return Sema::FRS_Success;
2282   };
2283 
2284   auto BuildEnd = [&] {
2285     *BEF = BEF_end;
2286     Sema::ForRangeStatus RangeStatus =
2287         SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, EndNameInfo,
2288                                           EndMemberLookup, CandidateSet,
2289                                           EndRange, EndExpr);
2290     if (RangeStatus != Sema::FRS_Success) {
2291       if (RangeStatus == Sema::FRS_DiagnosticIssued)
2292         SemaRef.Diag(EndRange->getBeginLoc(), diag::note_in_for_range)
2293             << ColonLoc << BEF_end << EndRange->getType();
2294       return RangeStatus;
2295     }
2296     if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc,
2297                               diag::err_for_range_iter_deduction_failure)) {
2298       NoteForRangeBeginEndFunction(SemaRef, EndExpr->get(), *BEF);
2299       return Sema::FRS_DiagnosticIssued;
2300     }
2301     return Sema::FRS_Success;
2302   };
2303 
2304   if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) {
2305     // - if _RangeT is a class type, the unqualified-ids begin and end are
2306     //   looked up in the scope of class _RangeT as if by class member access
2307     //   lookup (3.4.5), and if either (or both) finds at least one
2308     //   declaration, begin-expr and end-expr are __range.begin() and
2309     //   __range.end(), respectively;
2310     SemaRef.LookupQualifiedName(BeginMemberLookup, D);
2311     if (BeginMemberLookup.isAmbiguous())
2312       return Sema::FRS_DiagnosticIssued;
2313 
2314     SemaRef.LookupQualifiedName(EndMemberLookup, D);
2315     if (EndMemberLookup.isAmbiguous())
2316       return Sema::FRS_DiagnosticIssued;
2317 
2318     if (BeginMemberLookup.empty() != EndMemberLookup.empty()) {
2319       // Look up the non-member form of the member we didn't find, first.
2320       // This way we prefer a "no viable 'end'" diagnostic over a "i found
2321       // a 'begin' but ignored it because there was no member 'end'"
2322       // diagnostic.
2323       auto BuildNonmember = [&](
2324           BeginEndFunction BEFFound, LookupResult &Found,
2325           llvm::function_ref<Sema::ForRangeStatus()> BuildFound,
2326           llvm::function_ref<Sema::ForRangeStatus()> BuildNotFound) {
2327         LookupResult OldFound = std::move(Found);
2328         Found.clear();
2329 
2330         if (Sema::ForRangeStatus Result = BuildNotFound())
2331           return Result;
2332 
2333         switch (BuildFound()) {
2334         case Sema::FRS_Success:
2335           return Sema::FRS_Success;
2336 
2337         case Sema::FRS_NoViableFunction:
2338           CandidateSet->NoteCandidates(
2339               PartialDiagnosticAt(BeginRange->getBeginLoc(),
2340                                   SemaRef.PDiag(diag::err_for_range_invalid)
2341                                       << BeginRange->getType() << BEFFound),
2342               SemaRef, OCD_AllCandidates, BeginRange);
2343           LLVM_FALLTHROUGH;
2344 
2345         case Sema::FRS_DiagnosticIssued:
2346           for (NamedDecl *D : OldFound) {
2347             SemaRef.Diag(D->getLocation(),
2348                          diag::note_for_range_member_begin_end_ignored)
2349                 << BeginRange->getType() << BEFFound;
2350           }
2351           return Sema::FRS_DiagnosticIssued;
2352         }
2353         llvm_unreachable("unexpected ForRangeStatus");
2354       };
2355       if (BeginMemberLookup.empty())
2356         return BuildNonmember(BEF_end, EndMemberLookup, BuildEnd, BuildBegin);
2357       return BuildNonmember(BEF_begin, BeginMemberLookup, BuildBegin, BuildEnd);
2358     }
2359   } else {
2360     // - otherwise, begin-expr and end-expr are begin(__range) and
2361     //   end(__range), respectively, where begin and end are looked up with
2362     //   argument-dependent lookup (3.4.2). For the purposes of this name
2363     //   lookup, namespace std is an associated namespace.
2364   }
2365 
2366   if (Sema::ForRangeStatus Result = BuildBegin())
2367     return Result;
2368   return BuildEnd();
2369 }
2370 
2371 /// Speculatively attempt to dereference an invalid range expression.
2372 /// If the attempt fails, this function will return a valid, null StmtResult
2373 /// and emit no diagnostics.
2374 static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S,
2375                                                  SourceLocation ForLoc,
2376                                                  SourceLocation CoawaitLoc,
2377                                                  Stmt *InitStmt,
2378                                                  Stmt *LoopVarDecl,
2379                                                  SourceLocation ColonLoc,
2380                                                  Expr *Range,
2381                                                  SourceLocation RangeLoc,
2382                                                  SourceLocation RParenLoc) {
2383   // Determine whether we can rebuild the for-range statement with a
2384   // dereferenced range expression.
2385   ExprResult AdjustedRange;
2386   {
2387     Sema::SFINAETrap Trap(SemaRef);
2388 
2389     AdjustedRange = SemaRef.BuildUnaryOp(S, RangeLoc, UO_Deref, Range);
2390     if (AdjustedRange.isInvalid())
2391       return StmtResult();
2392 
2393     StmtResult SR = SemaRef.ActOnCXXForRangeStmt(
2394         S, ForLoc, CoawaitLoc, InitStmt, LoopVarDecl, ColonLoc,
2395         AdjustedRange.get(), RParenLoc, Sema::BFRK_Check);
2396     if (SR.isInvalid())
2397       return StmtResult();
2398   }
2399 
2400   // The attempt to dereference worked well enough that it could produce a valid
2401   // loop. Produce a fixit, and rebuild the loop with diagnostics enabled, in
2402   // case there are any other (non-fatal) problems with it.
2403   SemaRef.Diag(RangeLoc, diag::err_for_range_dereference)
2404     << Range->getType() << FixItHint::CreateInsertion(RangeLoc, "*");
2405   return SemaRef.ActOnCXXForRangeStmt(
2406       S, ForLoc, CoawaitLoc, InitStmt, LoopVarDecl, ColonLoc,
2407       AdjustedRange.get(), RParenLoc, Sema::BFRK_Rebuild);
2408 }
2409 
2410 /// BuildCXXForRangeStmt - Build or instantiate a C++11 for-range statement.
2411 StmtResult Sema::BuildCXXForRangeStmt(SourceLocation ForLoc,
2412                                       SourceLocation CoawaitLoc, Stmt *InitStmt,
2413                                       SourceLocation ColonLoc, Stmt *RangeDecl,
2414                                       Stmt *Begin, Stmt *End, Expr *Cond,
2415                                       Expr *Inc, Stmt *LoopVarDecl,
2416                                       SourceLocation RParenLoc,
2417                                       BuildForRangeKind Kind) {
2418   // FIXME: This should not be used during template instantiation. We should
2419   // pick up the set of unqualified lookup results for the != and + operators
2420   // in the initial parse.
2421   //
2422   // Testcase (accepts-invalid):
2423   //   template<typename T> void f() { for (auto x : T()) {} }
2424   //   namespace N { struct X { X begin(); X end(); int operator*(); }; }
2425   //   bool operator!=(N::X, N::X); void operator++(N::X);
2426   //   void g() { f<N::X>(); }
2427   Scope *S = getCurScope();
2428 
2429   DeclStmt *RangeDS = cast<DeclStmt>(RangeDecl);
2430   VarDecl *RangeVar = cast<VarDecl>(RangeDS->getSingleDecl());
2431   QualType RangeVarType = RangeVar->getType();
2432 
2433   DeclStmt *LoopVarDS = cast<DeclStmt>(LoopVarDecl);
2434   VarDecl *LoopVar = cast<VarDecl>(LoopVarDS->getSingleDecl());
2435 
2436   StmtResult BeginDeclStmt = Begin;
2437   StmtResult EndDeclStmt = End;
2438   ExprResult NotEqExpr = Cond, IncrExpr = Inc;
2439 
2440   if (RangeVarType->isDependentType()) {
2441     // The range is implicitly used as a placeholder when it is dependent.
2442     RangeVar->markUsed(Context);
2443 
2444     // Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill
2445     // them in properly when we instantiate the loop.
2446     if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
2447       if (auto *DD = dyn_cast<DecompositionDecl>(LoopVar))
2448         for (auto *Binding : DD->bindings())
2449           Binding->setType(Context.DependentTy);
2450       LoopVar->setType(SubstAutoType(LoopVar->getType(), Context.DependentTy));
2451     }
2452   } else if (!BeginDeclStmt.get()) {
2453     SourceLocation RangeLoc = RangeVar->getLocation();
2454 
2455     const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
2456 
2457     ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2458                                                 VK_LValue, ColonLoc);
2459     if (BeginRangeRef.isInvalid())
2460       return StmtError();
2461 
2462     ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2463                                               VK_LValue, ColonLoc);
2464     if (EndRangeRef.isInvalid())
2465       return StmtError();
2466 
2467     QualType AutoType = Context.getAutoDeductType();
2468     Expr *Range = RangeVar->getInit();
2469     if (!Range)
2470       return StmtError();
2471     QualType RangeType = Range->getType();
2472 
2473     if (RequireCompleteType(RangeLoc, RangeType,
2474                             diag::err_for_range_incomplete_type))
2475       return StmtError();
2476 
2477     // Build auto __begin = begin-expr, __end = end-expr.
2478     // Divide by 2, since the variables are in the inner scope (loop body).
2479     const auto DepthStr = std::to_string(S->getDepth() / 2);
2480     VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2481                                              std::string("__begin") + DepthStr);
2482     VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2483                                            std::string("__end") + DepthStr);
2484 
2485     // Build begin-expr and end-expr and attach to __begin and __end variables.
2486     ExprResult BeginExpr, EndExpr;
2487     if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) {
2488       // - if _RangeT is an array type, begin-expr and end-expr are __range and
2489       //   __range + __bound, respectively, where __bound is the array bound. If
2490       //   _RangeT is an array of unknown size or an array of incomplete type,
2491       //   the program is ill-formed;
2492 
2493       // begin-expr is __range.
2494       BeginExpr = BeginRangeRef;
2495       if (!CoawaitLoc.isInvalid()) {
2496         BeginExpr = ActOnCoawaitExpr(S, ColonLoc, BeginExpr.get());
2497         if (BeginExpr.isInvalid())
2498           return StmtError();
2499       }
2500       if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc,
2501                                 diag::err_for_range_iter_deduction_failure)) {
2502         NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2503         return StmtError();
2504       }
2505 
2506       // Find the array bound.
2507       ExprResult BoundExpr;
2508       if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(UnqAT))
2509         BoundExpr = IntegerLiteral::Create(
2510             Context, CAT->getSize(), Context.getPointerDiffType(), RangeLoc);
2511       else if (const VariableArrayType *VAT =
2512                dyn_cast<VariableArrayType>(UnqAT)) {
2513         // For a variably modified type we can't just use the expression within
2514         // the array bounds, since we don't want that to be re-evaluated here.
2515         // Rather, we need to determine what it was when the array was first
2516         // created - so we resort to using sizeof(vla)/sizeof(element).
2517         // For e.g.
2518         //  void f(int b) {
2519         //    int vla[b];
2520         //    b = -1;   <-- This should not affect the num of iterations below
2521         //    for (int &c : vla) { .. }
2522         //  }
2523 
2524         // FIXME: This results in codegen generating IR that recalculates the
2525         // run-time number of elements (as opposed to just using the IR Value
2526         // that corresponds to the run-time value of each bound that was
2527         // generated when the array was created.) If this proves too embarrassing
2528         // even for unoptimized IR, consider passing a magic-value/cookie to
2529         // codegen that then knows to simply use that initial llvm::Value (that
2530         // corresponds to the bound at time of array creation) within
2531         // getelementptr.  But be prepared to pay the price of increasing a
2532         // customized form of coupling between the two components - which  could
2533         // be hard to maintain as the codebase evolves.
2534 
2535         ExprResult SizeOfVLAExprR = ActOnUnaryExprOrTypeTraitExpr(
2536             EndVar->getLocation(), UETT_SizeOf,
2537             /*IsType=*/true,
2538             CreateParsedType(VAT->desugar(), Context.getTrivialTypeSourceInfo(
2539                                                  VAT->desugar(), RangeLoc))
2540                 .getAsOpaquePtr(),
2541             EndVar->getSourceRange());
2542         if (SizeOfVLAExprR.isInvalid())
2543           return StmtError();
2544 
2545         ExprResult SizeOfEachElementExprR = ActOnUnaryExprOrTypeTraitExpr(
2546             EndVar->getLocation(), UETT_SizeOf,
2547             /*IsType=*/true,
2548             CreateParsedType(VAT->desugar(),
2549                              Context.getTrivialTypeSourceInfo(
2550                                  VAT->getElementType(), RangeLoc))
2551                 .getAsOpaquePtr(),
2552             EndVar->getSourceRange());
2553         if (SizeOfEachElementExprR.isInvalid())
2554           return StmtError();
2555 
2556         BoundExpr =
2557             ActOnBinOp(S, EndVar->getLocation(), tok::slash,
2558                        SizeOfVLAExprR.get(), SizeOfEachElementExprR.get());
2559         if (BoundExpr.isInvalid())
2560           return StmtError();
2561 
2562       } else {
2563         // Can't be a DependentSizedArrayType or an IncompleteArrayType since
2564         // UnqAT is not incomplete and Range is not type-dependent.
2565         llvm_unreachable("Unexpected array type in for-range");
2566       }
2567 
2568       // end-expr is __range + __bound.
2569       EndExpr = ActOnBinOp(S, ColonLoc, tok::plus, EndRangeRef.get(),
2570                            BoundExpr.get());
2571       if (EndExpr.isInvalid())
2572         return StmtError();
2573       if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc,
2574                                 diag::err_for_range_iter_deduction_failure)) {
2575         NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2576         return StmtError();
2577       }
2578     } else {
2579       OverloadCandidateSet CandidateSet(RangeLoc,
2580                                         OverloadCandidateSet::CSK_Normal);
2581       BeginEndFunction BEFFailure;
2582       ForRangeStatus RangeStatus = BuildNonArrayForRange(
2583           *this, BeginRangeRef.get(), EndRangeRef.get(), RangeType, BeginVar,
2584           EndVar, ColonLoc, CoawaitLoc, &CandidateSet, &BeginExpr, &EndExpr,
2585           &BEFFailure);
2586 
2587       if (Kind == BFRK_Build && RangeStatus == FRS_NoViableFunction &&
2588           BEFFailure == BEF_begin) {
2589         // If the range is being built from an array parameter, emit a
2590         // a diagnostic that it is being treated as a pointer.
2591         if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Range)) {
2592           if (ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
2593             QualType ArrayTy = PVD->getOriginalType();
2594             QualType PointerTy = PVD->getType();
2595             if (PointerTy->isPointerType() && ArrayTy->isArrayType()) {
2596               Diag(Range->getBeginLoc(), diag::err_range_on_array_parameter)
2597                   << RangeLoc << PVD << ArrayTy << PointerTy;
2598               Diag(PVD->getLocation(), diag::note_declared_at);
2599               return StmtError();
2600             }
2601           }
2602         }
2603 
2604         // If building the range failed, try dereferencing the range expression
2605         // unless a diagnostic was issued or the end function is problematic.
2606         StmtResult SR = RebuildForRangeWithDereference(*this, S, ForLoc,
2607                                                        CoawaitLoc, InitStmt,
2608                                                        LoopVarDecl, ColonLoc,
2609                                                        Range, RangeLoc,
2610                                                        RParenLoc);
2611         if (SR.isInvalid() || SR.isUsable())
2612           return SR;
2613       }
2614 
2615       // Otherwise, emit diagnostics if we haven't already.
2616       if (RangeStatus == FRS_NoViableFunction) {
2617         Expr *Range = BEFFailure ? EndRangeRef.get() : BeginRangeRef.get();
2618         CandidateSet.NoteCandidates(
2619             PartialDiagnosticAt(Range->getBeginLoc(),
2620                                 PDiag(diag::err_for_range_invalid)
2621                                     << RangeLoc << Range->getType()
2622                                     << BEFFailure),
2623             *this, OCD_AllCandidates, Range);
2624       }
2625       // Return an error if no fix was discovered.
2626       if (RangeStatus != FRS_Success)
2627         return StmtError();
2628     }
2629 
2630     assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() &&
2631            "invalid range expression in for loop");
2632 
2633     // C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same.
2634     // C++1z removes this restriction.
2635     QualType BeginType = BeginVar->getType(), EndType = EndVar->getType();
2636     if (!Context.hasSameType(BeginType, EndType)) {
2637       Diag(RangeLoc, getLangOpts().CPlusPlus17
2638                          ? diag::warn_for_range_begin_end_types_differ
2639                          : diag::ext_for_range_begin_end_types_differ)
2640           << BeginType << EndType;
2641       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2642       NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2643     }
2644 
2645     BeginDeclStmt =
2646         ActOnDeclStmt(ConvertDeclToDeclGroup(BeginVar), ColonLoc, ColonLoc);
2647     EndDeclStmt =
2648         ActOnDeclStmt(ConvertDeclToDeclGroup(EndVar), ColonLoc, ColonLoc);
2649 
2650     const QualType BeginRefNonRefType = BeginType.getNonReferenceType();
2651     ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2652                                            VK_LValue, ColonLoc);
2653     if (BeginRef.isInvalid())
2654       return StmtError();
2655 
2656     ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(),
2657                                          VK_LValue, ColonLoc);
2658     if (EndRef.isInvalid())
2659       return StmtError();
2660 
2661     // Build and check __begin != __end expression.
2662     NotEqExpr = ActOnBinOp(S, ColonLoc, tok::exclaimequal,
2663                            BeginRef.get(), EndRef.get());
2664     if (!NotEqExpr.isInvalid())
2665       NotEqExpr = CheckBooleanCondition(ColonLoc, NotEqExpr.get());
2666     if (!NotEqExpr.isInvalid())
2667       NotEqExpr =
2668           ActOnFinishFullExpr(NotEqExpr.get(), /*DiscardedValue*/ false);
2669     if (NotEqExpr.isInvalid()) {
2670       Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2671         << RangeLoc << 0 << BeginRangeRef.get()->getType();
2672       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2673       if (!Context.hasSameType(BeginType, EndType))
2674         NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2675       return StmtError();
2676     }
2677 
2678     // Build and check ++__begin expression.
2679     BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2680                                 VK_LValue, ColonLoc);
2681     if (BeginRef.isInvalid())
2682       return StmtError();
2683 
2684     IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get());
2685     if (!IncrExpr.isInvalid() && CoawaitLoc.isValid())
2686       // FIXME: getCurScope() should not be used during template instantiation.
2687       // We should pick up the set of unqualified lookup results for operator
2688       // co_await during the initial parse.
2689       IncrExpr = ActOnCoawaitExpr(S, CoawaitLoc, IncrExpr.get());
2690     if (!IncrExpr.isInvalid())
2691       IncrExpr = ActOnFinishFullExpr(IncrExpr.get(), /*DiscardedValue*/ false);
2692     if (IncrExpr.isInvalid()) {
2693       Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2694         << RangeLoc << 2 << BeginRangeRef.get()->getType() ;
2695       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2696       return StmtError();
2697     }
2698 
2699     // Build and check *__begin  expression.
2700     BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2701                                 VK_LValue, ColonLoc);
2702     if (BeginRef.isInvalid())
2703       return StmtError();
2704 
2705     ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get());
2706     if (DerefExpr.isInvalid()) {
2707       Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2708         << RangeLoc << 1 << BeginRangeRef.get()->getType();
2709       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2710       return StmtError();
2711     }
2712 
2713     // Attach  *__begin  as initializer for VD. Don't touch it if we're just
2714     // trying to determine whether this would be a valid range.
2715     if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
2716       AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false);
2717       if (LoopVar->isInvalidDecl() ||
2718           (LoopVar->getInit() && LoopVar->getInit()->containsErrors()))
2719         NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2720     }
2721   }
2722 
2723   // Don't bother to actually allocate the result if we're just trying to
2724   // determine whether it would be valid.
2725   if (Kind == BFRK_Check)
2726     return StmtResult();
2727 
2728   // In OpenMP loop region loop control variable must be private. Perform
2729   // analysis of first part (if any).
2730   if (getLangOpts().OpenMP >= 50 && BeginDeclStmt.isUsable())
2731     ActOnOpenMPLoopInitialization(ForLoc, BeginDeclStmt.get());
2732 
2733   return new (Context) CXXForRangeStmt(
2734       InitStmt, RangeDS, cast_or_null<DeclStmt>(BeginDeclStmt.get()),
2735       cast_or_null<DeclStmt>(EndDeclStmt.get()), NotEqExpr.get(),
2736       IncrExpr.get(), LoopVarDS, /*Body=*/nullptr, ForLoc, CoawaitLoc,
2737       ColonLoc, RParenLoc);
2738 }
2739 
2740 /// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach
2741 /// statement.
2742 StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) {
2743   if (!S || !B)
2744     return StmtError();
2745   ObjCForCollectionStmt * ForStmt = cast<ObjCForCollectionStmt>(S);
2746 
2747   ForStmt->setBody(B);
2748   return S;
2749 }
2750 
2751 // Warn when the loop variable is a const reference that creates a copy.
2752 // Suggest using the non-reference type for copies.  If a copy can be prevented
2753 // suggest the const reference type that would do so.
2754 // For instance, given "for (const &Foo : Range)", suggest
2755 // "for (const Foo : Range)" to denote a copy is made for the loop.  If
2756 // possible, also suggest "for (const &Bar : Range)" if this type prevents
2757 // the copy altogether.
2758 static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef,
2759                                                     const VarDecl *VD,
2760                                                     QualType RangeInitType) {
2761   const Expr *InitExpr = VD->getInit();
2762   if (!InitExpr)
2763     return;
2764 
2765   QualType VariableType = VD->getType();
2766 
2767   if (auto Cleanups = dyn_cast<ExprWithCleanups>(InitExpr))
2768     if (!Cleanups->cleanupsHaveSideEffects())
2769       InitExpr = Cleanups->getSubExpr();
2770 
2771   const MaterializeTemporaryExpr *MTE =
2772       dyn_cast<MaterializeTemporaryExpr>(InitExpr);
2773 
2774   // No copy made.
2775   if (!MTE)
2776     return;
2777 
2778   const Expr *E = MTE->getSubExpr()->IgnoreImpCasts();
2779 
2780   // Searching for either UnaryOperator for dereference of a pointer or
2781   // CXXOperatorCallExpr for handling iterators.
2782   while (!isa<CXXOperatorCallExpr>(E) && !isa<UnaryOperator>(E)) {
2783     if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(E)) {
2784       E = CCE->getArg(0);
2785     } else if (const CXXMemberCallExpr *Call = dyn_cast<CXXMemberCallExpr>(E)) {
2786       const MemberExpr *ME = cast<MemberExpr>(Call->getCallee());
2787       E = ME->getBase();
2788     } else {
2789       const MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E);
2790       E = MTE->getSubExpr();
2791     }
2792     E = E->IgnoreImpCasts();
2793   }
2794 
2795   QualType ReferenceReturnType;
2796   if (isa<UnaryOperator>(E)) {
2797     ReferenceReturnType = SemaRef.Context.getLValueReferenceType(E->getType());
2798   } else {
2799     const CXXOperatorCallExpr *Call = cast<CXXOperatorCallExpr>(E);
2800     const FunctionDecl *FD = Call->getDirectCallee();
2801     QualType ReturnType = FD->getReturnType();
2802     if (ReturnType->isReferenceType())
2803       ReferenceReturnType = ReturnType;
2804   }
2805 
2806   if (!ReferenceReturnType.isNull()) {
2807     // Loop variable creates a temporary.  Suggest either to go with
2808     // non-reference loop variable to indicate a copy is made, or
2809     // the correct type to bind a const reference.
2810     SemaRef.Diag(VD->getLocation(),
2811                  diag::warn_for_range_const_ref_binds_temp_built_from_ref)
2812         << VD << VariableType << ReferenceReturnType;
2813     QualType NonReferenceType = VariableType.getNonReferenceType();
2814     NonReferenceType.removeLocalConst();
2815     QualType NewReferenceType =
2816         SemaRef.Context.getLValueReferenceType(E->getType().withConst());
2817     SemaRef.Diag(VD->getBeginLoc(), diag::note_use_type_or_non_reference)
2818         << NonReferenceType << NewReferenceType << VD->getSourceRange()
2819         << FixItHint::CreateRemoval(VD->getTypeSpecEndLoc());
2820   } else if (!VariableType->isRValueReferenceType()) {
2821     // The range always returns a copy, so a temporary is always created.
2822     // Suggest removing the reference from the loop variable.
2823     // If the type is a rvalue reference do not warn since that changes the
2824     // semantic of the code.
2825     SemaRef.Diag(VD->getLocation(), diag::warn_for_range_ref_binds_ret_temp)
2826         << VD << RangeInitType;
2827     QualType NonReferenceType = VariableType.getNonReferenceType();
2828     NonReferenceType.removeLocalConst();
2829     SemaRef.Diag(VD->getBeginLoc(), diag::note_use_non_reference_type)
2830         << NonReferenceType << VD->getSourceRange()
2831         << FixItHint::CreateRemoval(VD->getTypeSpecEndLoc());
2832   }
2833 }
2834 
2835 /// Determines whether the @p VariableType's declaration is a record with the
2836 /// clang::trivial_abi attribute.
2837 static bool hasTrivialABIAttr(QualType VariableType) {
2838   if (CXXRecordDecl *RD = VariableType->getAsCXXRecordDecl())
2839     return RD->hasAttr<TrivialABIAttr>();
2840 
2841   return false;
2842 }
2843 
2844 // Warns when the loop variable can be changed to a reference type to
2845 // prevent a copy.  For instance, if given "for (const Foo x : Range)" suggest
2846 // "for (const Foo &x : Range)" if this form does not make a copy.
2847 static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef,
2848                                                 const VarDecl *VD) {
2849   const Expr *InitExpr = VD->getInit();
2850   if (!InitExpr)
2851     return;
2852 
2853   QualType VariableType = VD->getType();
2854 
2855   if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(InitExpr)) {
2856     if (!CE->getConstructor()->isCopyConstructor())
2857       return;
2858   } else if (const CastExpr *CE = dyn_cast<CastExpr>(InitExpr)) {
2859     if (CE->getCastKind() != CK_LValueToRValue)
2860       return;
2861   } else {
2862     return;
2863   }
2864 
2865   // Small trivially copyable types are cheap to copy. Do not emit the
2866   // diagnostic for these instances. 64 bytes is a common size of a cache line.
2867   // (The function `getTypeSize` returns the size in bits.)
2868   ASTContext &Ctx = SemaRef.Context;
2869   if (Ctx.getTypeSize(VariableType) <= 64 * 8 &&
2870       (VariableType.isTriviallyCopyableType(Ctx) ||
2871        hasTrivialABIAttr(VariableType)))
2872     return;
2873 
2874   // Suggest changing from a const variable to a const reference variable
2875   // if doing so will prevent a copy.
2876   SemaRef.Diag(VD->getLocation(), diag::warn_for_range_copy)
2877       << VD << VariableType;
2878   SemaRef.Diag(VD->getBeginLoc(), diag::note_use_reference_type)
2879       << SemaRef.Context.getLValueReferenceType(VariableType)
2880       << VD->getSourceRange()
2881       << FixItHint::CreateInsertion(VD->getLocation(), "&");
2882 }
2883 
2884 /// DiagnoseForRangeVariableCopies - Diagnose three cases and fixes for them.
2885 /// 1) for (const foo &x : foos) where foos only returns a copy.  Suggest
2886 ///    using "const foo x" to show that a copy is made
2887 /// 2) for (const bar &x : foos) where bar is a temporary initialized by bar.
2888 ///    Suggest either "const bar x" to keep the copying or "const foo& x" to
2889 ///    prevent the copy.
2890 /// 3) for (const foo x : foos) where x is constructed from a reference foo.
2891 ///    Suggest "const foo &x" to prevent the copy.
2892 static void DiagnoseForRangeVariableCopies(Sema &SemaRef,
2893                                            const CXXForRangeStmt *ForStmt) {
2894   if (SemaRef.inTemplateInstantiation())
2895     return;
2896 
2897   if (SemaRef.Diags.isIgnored(
2898           diag::warn_for_range_const_ref_binds_temp_built_from_ref,
2899           ForStmt->getBeginLoc()) &&
2900       SemaRef.Diags.isIgnored(diag::warn_for_range_ref_binds_ret_temp,
2901                               ForStmt->getBeginLoc()) &&
2902       SemaRef.Diags.isIgnored(diag::warn_for_range_copy,
2903                               ForStmt->getBeginLoc())) {
2904     return;
2905   }
2906 
2907   const VarDecl *VD = ForStmt->getLoopVariable();
2908   if (!VD)
2909     return;
2910 
2911   QualType VariableType = VD->getType();
2912 
2913   if (VariableType->isIncompleteType())
2914     return;
2915 
2916   const Expr *InitExpr = VD->getInit();
2917   if (!InitExpr)
2918     return;
2919 
2920   if (InitExpr->getExprLoc().isMacroID())
2921     return;
2922 
2923   if (VariableType->isReferenceType()) {
2924     DiagnoseForRangeReferenceVariableCopies(SemaRef, VD,
2925                                             ForStmt->getRangeInit()->getType());
2926   } else if (VariableType.isConstQualified()) {
2927     DiagnoseForRangeConstVariableCopies(SemaRef, VD);
2928   }
2929 }
2930 
2931 /// FinishCXXForRangeStmt - Attach the body to a C++0x for-range statement.
2932 /// This is a separate step from ActOnCXXForRangeStmt because analysis of the
2933 /// body cannot be performed until after the type of the range variable is
2934 /// determined.
2935 StmtResult Sema::FinishCXXForRangeStmt(Stmt *S, Stmt *B) {
2936   if (!S || !B)
2937     return StmtError();
2938 
2939   if (isa<ObjCForCollectionStmt>(S))
2940     return FinishObjCForCollectionStmt(S, B);
2941 
2942   CXXForRangeStmt *ForStmt = cast<CXXForRangeStmt>(S);
2943   ForStmt->setBody(B);
2944 
2945   DiagnoseEmptyStmtBody(ForStmt->getRParenLoc(), B,
2946                         diag::warn_empty_range_based_for_body);
2947 
2948   DiagnoseForRangeVariableCopies(*this, ForStmt);
2949 
2950   return S;
2951 }
2952 
2953 StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc,
2954                                SourceLocation LabelLoc,
2955                                LabelDecl *TheDecl) {
2956   setFunctionHasBranchIntoScope();
2957   TheDecl->markUsed(Context);
2958   return new (Context) GotoStmt(TheDecl, GotoLoc, LabelLoc);
2959 }
2960 
2961 StmtResult
2962 Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
2963                             Expr *E) {
2964   // Convert operand to void*
2965   if (!E->isTypeDependent()) {
2966     QualType ETy = E->getType();
2967     QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
2968     ExprResult ExprRes = E;
2969     AssignConvertType ConvTy =
2970       CheckSingleAssignmentConstraints(DestTy, ExprRes);
2971     if (ExprRes.isInvalid())
2972       return StmtError();
2973     E = ExprRes.get();
2974     if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
2975       return StmtError();
2976   }
2977 
2978   ExprResult ExprRes = ActOnFinishFullExpr(E, /*DiscardedValue*/ false);
2979   if (ExprRes.isInvalid())
2980     return StmtError();
2981   E = ExprRes.get();
2982 
2983   setFunctionHasIndirectGoto();
2984 
2985   return new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E);
2986 }
2987 
2988 static void CheckJumpOutOfSEHFinally(Sema &S, SourceLocation Loc,
2989                                      const Scope &DestScope) {
2990   if (!S.CurrentSEHFinally.empty() &&
2991       DestScope.Contains(*S.CurrentSEHFinally.back())) {
2992     S.Diag(Loc, diag::warn_jump_out_of_seh_finally);
2993   }
2994 }
2995 
2996 StmtResult
2997 Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
2998   Scope *S = CurScope->getContinueParent();
2999   if (!S) {
3000     // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
3001     return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
3002   }
3003   CheckJumpOutOfSEHFinally(*this, ContinueLoc, *S);
3004 
3005   return new (Context) ContinueStmt(ContinueLoc);
3006 }
3007 
3008 StmtResult
3009 Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
3010   Scope *S = CurScope->getBreakParent();
3011   if (!S) {
3012     // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
3013     return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
3014   }
3015   if (S->isOpenMPLoopScope())
3016     return StmtError(Diag(BreakLoc, diag::err_omp_loop_cannot_use_stmt)
3017                      << "break");
3018   CheckJumpOutOfSEHFinally(*this, BreakLoc, *S);
3019 
3020   return new (Context) BreakStmt(BreakLoc);
3021 }
3022 
3023 /// Determine whether the given expression is a candidate for
3024 /// copy elision in either a return statement or a throw expression.
3025 ///
3026 /// \param ReturnType If we're determining the copy elision candidate for
3027 /// a return statement, this is the return type of the function. If we're
3028 /// determining the copy elision candidate for a throw expression, this will
3029 /// be a NULL type.
3030 ///
3031 /// \param E The expression being returned from the function or block, or
3032 /// being thrown.
3033 ///
3034 /// \param CESK Whether we allow function parameters or
3035 /// id-expressions that could be moved out of the function to be considered NRVO
3036 /// candidates. C++ prohibits these for NRVO itself, but we re-use this logic to
3037 /// determine whether we should try to move as part of a return or throw (which
3038 /// does allow function parameters).
3039 ///
3040 /// \returns The NRVO candidate variable, if the return statement may use the
3041 /// NRVO, or NULL if there is no such candidate.
3042 VarDecl *Sema::getCopyElisionCandidate(QualType ReturnType, Expr *E,
3043                                        CopyElisionSemanticsKind CESK) {
3044   // - in a return statement in a function [where] ...
3045   // ... the expression is the name of a non-volatile automatic object ...
3046   DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E->IgnoreParens());
3047   if (!DR || DR->refersToEnclosingVariableOrCapture())
3048     return nullptr;
3049   VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
3050   if (!VD)
3051     return nullptr;
3052 
3053   if (isCopyElisionCandidate(ReturnType, VD, CESK))
3054     return VD;
3055   return nullptr;
3056 }
3057 
3058 bool Sema::isCopyElisionCandidate(QualType ReturnType, const VarDecl *VD,
3059                                   CopyElisionSemanticsKind CESK) {
3060   QualType VDType = VD->getType();
3061   // - in a return statement in a function with ...
3062   // ... a class return type ...
3063   if (!ReturnType.isNull() && !ReturnType->isDependentType()) {
3064     if (!ReturnType->isRecordType())
3065       return false;
3066     // ... the same cv-unqualified type as the function return type ...
3067     // When considering moving this expression out, allow dissimilar types.
3068     if (!(CESK & CES_AllowDifferentTypes) && !VDType->isDependentType() &&
3069         !Context.hasSameUnqualifiedType(ReturnType, VDType))
3070       return false;
3071   }
3072 
3073   // ...object (other than a function or catch-clause parameter)...
3074   if (VD->getKind() != Decl::Var &&
3075       !((CESK & CES_AllowParameters) && VD->getKind() == Decl::ParmVar))
3076     return false;
3077   if (!(CESK & CES_AllowExceptionVariables) && VD->isExceptionVariable())
3078     return false;
3079 
3080   // ...automatic...
3081   if (!VD->hasLocalStorage()) return false;
3082 
3083   // Return false if VD is a __block variable. We don't want to implicitly move
3084   // out of a __block variable during a return because we cannot assume the
3085   // variable will no longer be used.
3086   if (VD->hasAttr<BlocksAttr>()) return false;
3087 
3088   // ...non-volatile...
3089   if (VD->getType().isVolatileQualified())
3090     return false;
3091 
3092   if (CESK & CES_AllowDifferentTypes)
3093     return true;
3094 
3095   // Variables with higher required alignment than their type's ABI
3096   // alignment cannot use NRVO.
3097   if (!VD->getType()->isDependentType() && VD->hasAttr<AlignedAttr>() &&
3098       Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VD->getType()))
3099     return false;
3100 
3101   return true;
3102 }
3103 
3104 /// Try to perform the initialization of a potentially-movable value,
3105 /// which is the operand to a return or throw statement.
3106 ///
3107 /// This routine implements C++14 [class.copy]p32, which attempts to treat
3108 /// returned lvalues as rvalues in certain cases (to prefer move construction),
3109 /// then falls back to treating them as lvalues if that failed.
3110 ///
3111 /// \param ConvertingConstructorsOnly If true, follow [class.copy]p32 and reject
3112 /// resolutions that find non-constructors, such as derived-to-base conversions
3113 /// or `operator T()&&` member functions. If false, do consider such
3114 /// conversion sequences.
3115 ///
3116 /// \param Res We will fill this in if move-initialization was possible.
3117 /// If move-initialization is not possible, such that we must fall back to
3118 /// treating the operand as an lvalue, we will leave Res in its original
3119 /// invalid state.
3120 ///
3121 /// \returns Whether we need to do the second overload resolution. If the first
3122 /// overload resolution fails, or if the first overload resolution succeeds but
3123 /// the selected constructor/operator doesn't match the additional criteria, we
3124 /// need to do the second overload resolution.
3125 static bool TryMoveInitialization(Sema &S, const InitializedEntity &Entity,
3126                                   const VarDecl *NRVOCandidate,
3127                                   QualType ResultType, Expr *&Value,
3128                                   bool ConvertingConstructorsOnly,
3129                                   bool IsDiagnosticsCheck, ExprResult &Res) {
3130   ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(),
3131                             CK_NoOp, Value, VK_XValue, FPOptionsOverride());
3132 
3133   Expr *InitExpr = &AsRvalue;
3134 
3135   InitializationKind Kind = InitializationKind::CreateCopy(
3136       Value->getBeginLoc(), Value->getBeginLoc());
3137 
3138   InitializationSequence Seq(S, Entity, Kind, InitExpr);
3139 
3140   bool NeedSecondOverloadResolution = true;
3141   if (!Seq &&
3142       (IsDiagnosticsCheck || Seq.getFailedOverloadResult() != OR_Deleted)) {
3143     return NeedSecondOverloadResolution;
3144   }
3145 
3146   for (const InitializationSequence::Step &Step : Seq.steps()) {
3147     if (Step.Kind != InitializationSequence::SK_ConstructorInitialization &&
3148         Step.Kind != InitializationSequence::SK_UserConversion)
3149       continue;
3150 
3151     FunctionDecl *FD = Step.Function.Function;
3152     if (ConvertingConstructorsOnly) {
3153       if (isa<CXXConstructorDecl>(FD)) {
3154         // C++14 [class.copy]p32:
3155         // [...] If the first overload resolution fails or was not performed,
3156         // or if the type of the first parameter of the selected constructor
3157         // is not an rvalue reference to the object's type (possibly
3158         // cv-qualified), overload resolution is performed again, considering
3159         // the object as an lvalue.
3160         const RValueReferenceType *RRefType =
3161             FD->getParamDecl(0)->getType()->getAs<RValueReferenceType>();
3162         if (!RRefType)
3163           break;
3164         if (!S.Context.hasSameUnqualifiedType(RRefType->getPointeeType(),
3165                                               NRVOCandidate->getType()))
3166           break;
3167       } else {
3168         continue;
3169       }
3170     } else {
3171       if (isa<CXXConstructorDecl>(FD)) {
3172         // Check that overload resolution selected a constructor taking an
3173         // rvalue reference. If it selected an lvalue reference, then we
3174         // didn't need to cast this thing to an rvalue in the first place.
3175         if (!isa<RValueReferenceType>(FD->getParamDecl(0)->getType()))
3176           break;
3177       } else if (isa<CXXMethodDecl>(FD)) {
3178         // Check that overload resolution selected a conversion operator
3179         // taking an rvalue reference.
3180         if (cast<CXXMethodDecl>(FD)->getRefQualifier() != RQ_RValue)
3181           break;
3182       } else {
3183         continue;
3184       }
3185     }
3186 
3187     NeedSecondOverloadResolution = false;
3188     // Promote "AsRvalue" to the heap, since we now need this
3189     // expression node to persist.
3190     Value =
3191         ImplicitCastExpr::Create(S.Context, Value->getType(), CK_NoOp, Value,
3192                                  nullptr, VK_XValue, FPOptionsOverride());
3193 
3194     // Complete type-checking the initialization of the return type
3195     // using the constructor we found.
3196     Res = Seq.Perform(S, Entity, Kind, Value);
3197   }
3198 
3199   return NeedSecondOverloadResolution;
3200 }
3201 
3202 /// Perform the initialization of a potentially-movable value, which
3203 /// is the result of return value.
3204 ///
3205 /// This routine implements C++14 [class.copy]p32, which attempts to treat
3206 /// returned lvalues as rvalues in certain cases (to prefer move construction),
3207 /// then falls back to treating them as lvalues if that failed.
3208 ExprResult
3209 Sema::PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
3210                                       const VarDecl *NRVOCandidate,
3211                                       QualType ResultType,
3212                                       Expr *Value,
3213                                       bool AllowNRVO) {
3214   // C++14 [class.copy]p32:
3215   // When the criteria for elision of a copy/move operation are met, but not for
3216   // an exception-declaration, and the object to be copied is designated by an
3217   // lvalue, or when the expression in a return statement is a (possibly
3218   // parenthesized) id-expression that names an object with automatic storage
3219   // duration declared in the body or parameter-declaration-clause of the
3220   // innermost enclosing function or lambda-expression, overload resolution to
3221   // select the constructor for the copy is first performed as if the object
3222   // were designated by an rvalue.
3223   ExprResult Res = ExprError();
3224   bool NeedSecondOverloadResolution = true;
3225 
3226   if (AllowNRVO) {
3227     bool AffectedByCWG1579 = false;
3228 
3229     if (!NRVOCandidate) {
3230       NRVOCandidate = getCopyElisionCandidate(ResultType, Value, CES_Default);
3231       if (NRVOCandidate &&
3232           !getDiagnostics().isIgnored(diag::warn_return_std_move_in_cxx11,
3233                                       Value->getExprLoc())) {
3234         const VarDecl *NRVOCandidateInCXX11 =
3235             getCopyElisionCandidate(ResultType, Value, CES_FormerDefault);
3236         AffectedByCWG1579 = (!NRVOCandidateInCXX11);
3237       }
3238     }
3239 
3240     if (NRVOCandidate) {
3241       NeedSecondOverloadResolution = TryMoveInitialization(
3242           *this, Entity, NRVOCandidate, ResultType, Value, true, false, Res);
3243     }
3244 
3245     if (!NeedSecondOverloadResolution && AffectedByCWG1579) {
3246       QualType QT = NRVOCandidate->getType();
3247       if (QT.getNonReferenceType().getUnqualifiedType().isTriviallyCopyableType(
3248               Context)) {
3249         // Adding 'std::move' around a trivially copyable variable is probably
3250         // pointless. Don't suggest it.
3251       } else {
3252         // Common cases for this are returning unique_ptr<Derived> from a
3253         // function of return type unique_ptr<Base>, or returning T from a
3254         // function of return type Expected<T>. This is totally fine in a
3255         // post-CWG1579 world, but was not fine before.
3256         assert(!ResultType.isNull());
3257         SmallString<32> Str;
3258         Str += "std::move(";
3259         Str += NRVOCandidate->getDeclName().getAsString();
3260         Str += ")";
3261         Diag(Value->getExprLoc(), diag::warn_return_std_move_in_cxx11)
3262             << Value->getSourceRange() << NRVOCandidate->getDeclName()
3263             << ResultType << QT;
3264         Diag(Value->getExprLoc(), diag::note_add_std_move_in_cxx11)
3265             << FixItHint::CreateReplacement(Value->getSourceRange(), Str);
3266       }
3267     } else if (NeedSecondOverloadResolution &&
3268                !getDiagnostics().isIgnored(diag::warn_return_std_move,
3269                                            Value->getExprLoc())) {
3270       const VarDecl *FakeNRVOCandidate =
3271           getCopyElisionCandidate(QualType(), Value, CES_AsIfByStdMove);
3272       if (FakeNRVOCandidate) {
3273         QualType QT = FakeNRVOCandidate->getType();
3274         if (QT->isLValueReferenceType()) {
3275           // Adding 'std::move' around an lvalue reference variable's name is
3276           // dangerous. Don't suggest it.
3277         } else if (QT.getNonReferenceType()
3278                        .getUnqualifiedType()
3279                        .isTriviallyCopyableType(Context)) {
3280           // Adding 'std::move' around a trivially copyable variable is probably
3281           // pointless. Don't suggest it.
3282         } else {
3283           ExprResult FakeRes = ExprError();
3284           Expr *FakeValue = Value;
3285           TryMoveInitialization(*this, Entity, FakeNRVOCandidate, ResultType,
3286                                 FakeValue, false, true, FakeRes);
3287           if (!FakeRes.isInvalid()) {
3288             bool IsThrow =
3289                 (Entity.getKind() == InitializedEntity::EK_Exception);
3290             SmallString<32> Str;
3291             Str += "std::move(";
3292             Str += FakeNRVOCandidate->getDeclName().getAsString();
3293             Str += ")";
3294             Diag(Value->getExprLoc(), diag::warn_return_std_move)
3295                 << Value->getSourceRange()
3296                 << FakeNRVOCandidate->getDeclName() << IsThrow;
3297             Diag(Value->getExprLoc(), diag::note_add_std_move)
3298                 << FixItHint::CreateReplacement(Value->getSourceRange(), Str);
3299           }
3300         }
3301       }
3302     }
3303   }
3304 
3305   // Either we didn't meet the criteria for treating an lvalue as an rvalue,
3306   // above, or overload resolution failed. Either way, we need to try
3307   // (again) now with the return value expression as written.
3308   if (NeedSecondOverloadResolution)
3309     Res = PerformCopyInitialization(Entity, SourceLocation(), Value);
3310 
3311   return Res;
3312 }
3313 
3314 /// Determine whether the declared return type of the specified function
3315 /// contains 'auto'.
3316 static bool hasDeducedReturnType(FunctionDecl *FD) {
3317   const FunctionProtoType *FPT =
3318       FD->getTypeSourceInfo()->getType()->castAs<FunctionProtoType>();
3319   return FPT->getReturnType()->isUndeducedType();
3320 }
3321 
3322 /// ActOnCapScopeReturnStmt - Utility routine to type-check return statements
3323 /// for capturing scopes.
3324 ///
3325 StmtResult
3326 Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
3327   // If this is the first return we've seen, infer the return type.
3328   // [expr.prim.lambda]p4 in C++11; block literals follow the same rules.
3329   CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
3330   QualType FnRetType = CurCap->ReturnType;
3331   LambdaScopeInfo *CurLambda = dyn_cast<LambdaScopeInfo>(CurCap);
3332   bool HasDeducedReturnType =
3333       CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
3334 
3335   if (ExprEvalContexts.back().Context ==
3336           ExpressionEvaluationContext::DiscardedStatement &&
3337       (HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
3338     if (RetValExp) {
3339       ExprResult ER =
3340           ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3341       if (ER.isInvalid())
3342         return StmtError();
3343       RetValExp = ER.get();
3344     }
3345     return ReturnStmt::Create(Context, ReturnLoc, RetValExp,
3346                               /* NRVOCandidate=*/nullptr);
3347   }
3348 
3349   if (HasDeducedReturnType) {
3350     FunctionDecl *FD = CurLambda->CallOperator;
3351     // If we've already decided this lambda is invalid, e.g. because
3352     // we saw a `return` whose expression had an error, don't keep
3353     // trying to deduce its return type.
3354     if (FD->isInvalidDecl())
3355       return StmtError();
3356     // In C++1y, the return type may involve 'auto'.
3357     // FIXME: Blocks might have a return type of 'auto' explicitly specified.
3358     if (CurCap->ReturnType.isNull())
3359       CurCap->ReturnType = FD->getReturnType();
3360 
3361     AutoType *AT = CurCap->ReturnType->getContainedAutoType();
3362     assert(AT && "lost auto type from lambda return type");
3363     if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
3364       FD->setInvalidDecl();
3365       // FIXME: preserve the ill-formed return expression.
3366       return StmtError();
3367     }
3368     CurCap->ReturnType = FnRetType = FD->getReturnType();
3369   } else if (CurCap->HasImplicitReturnType) {
3370     // For blocks/lambdas with implicit return types, we check each return
3371     // statement individually, and deduce the common return type when the block
3372     // or lambda is completed.
3373     // FIXME: Fold this into the 'auto' codepath above.
3374     if (RetValExp && !isa<InitListExpr>(RetValExp)) {
3375       ExprResult Result = DefaultFunctionArrayLvalueConversion(RetValExp);
3376       if (Result.isInvalid())
3377         return StmtError();
3378       RetValExp = Result.get();
3379 
3380       // DR1048: even prior to C++14, we should use the 'auto' deduction rules
3381       // when deducing a return type for a lambda-expression (or by extension
3382       // for a block). These rules differ from the stated C++11 rules only in
3383       // that they remove top-level cv-qualifiers.
3384       if (!CurContext->isDependentContext())
3385         FnRetType = RetValExp->getType().getUnqualifiedType();
3386       else
3387         FnRetType = CurCap->ReturnType = Context.DependentTy;
3388     } else {
3389       if (RetValExp) {
3390         // C++11 [expr.lambda.prim]p4 bans inferring the result from an
3391         // initializer list, because it is not an expression (even
3392         // though we represent it as one). We still deduce 'void'.
3393         Diag(ReturnLoc, diag::err_lambda_return_init_list)
3394           << RetValExp->getSourceRange();
3395       }
3396 
3397       FnRetType = Context.VoidTy;
3398     }
3399 
3400     // Although we'll properly infer the type of the block once it's completed,
3401     // make sure we provide a return type now for better error recovery.
3402     if (CurCap->ReturnType.isNull())
3403       CurCap->ReturnType = FnRetType;
3404   }
3405   assert(!FnRetType.isNull());
3406 
3407   if (auto *CurBlock = dyn_cast<BlockScopeInfo>(CurCap)) {
3408     if (CurBlock->FunctionType->castAs<FunctionType>()->getNoReturnAttr()) {
3409       Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr);
3410       return StmtError();
3411     }
3412   } else if (auto *CurRegion = dyn_cast<CapturedRegionScopeInfo>(CurCap)) {
3413     Diag(ReturnLoc, diag::err_return_in_captured_stmt) << CurRegion->getRegionName();
3414     return StmtError();
3415   } else {
3416     assert(CurLambda && "unknown kind of captured scope");
3417     if (CurLambda->CallOperator->getType()
3418             ->castAs<FunctionType>()
3419             ->getNoReturnAttr()) {
3420       Diag(ReturnLoc, diag::err_noreturn_lambda_has_return_expr);
3421       return StmtError();
3422     }
3423   }
3424 
3425   // Otherwise, verify that this result type matches the previous one.  We are
3426   // pickier with blocks than for normal functions because we don't have GCC
3427   // compatibility to worry about here.
3428   const VarDecl *NRVOCandidate = nullptr;
3429   if (FnRetType->isDependentType()) {
3430     // Delay processing for now.  TODO: there are lots of dependent
3431     // types we can conclusively prove aren't void.
3432   } else if (FnRetType->isVoidType()) {
3433     if (RetValExp && !isa<InitListExpr>(RetValExp) &&
3434         !(getLangOpts().CPlusPlus &&
3435           (RetValExp->isTypeDependent() ||
3436            RetValExp->getType()->isVoidType()))) {
3437       if (!getLangOpts().CPlusPlus &&
3438           RetValExp->getType()->isVoidType())
3439         Diag(ReturnLoc, diag::ext_return_has_void_expr) << "literal" << 2;
3440       else {
3441         Diag(ReturnLoc, diag::err_return_block_has_expr);
3442         RetValExp = nullptr;
3443       }
3444     }
3445   } else if (!RetValExp) {
3446     return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
3447   } else if (!RetValExp->isTypeDependent()) {
3448     // we have a non-void block with an expression, continue checking
3449 
3450     // C99 6.8.6.4p3(136): The return statement is not an assignment. The
3451     // overlap restriction of subclause 6.5.16.1 does not apply to the case of
3452     // function return.
3453 
3454     // In C++ the return statement is handled via a copy initialization.
3455     // the C version of which boils down to CheckSingleAssignmentConstraints.
3456     NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
3457     InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
3458                                                                    FnRetType,
3459                                                       NRVOCandidate != nullptr);
3460     ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
3461                                                      FnRetType, RetValExp);
3462     if (Res.isInvalid()) {
3463       // FIXME: Cleanup temporaries here, anyway?
3464       return StmtError();
3465     }
3466     RetValExp = Res.get();
3467     CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc);
3468   } else {
3469     NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
3470   }
3471 
3472   if (RetValExp) {
3473     ExprResult ER =
3474         ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3475     if (ER.isInvalid())
3476       return StmtError();
3477     RetValExp = ER.get();
3478   }
3479   auto *Result =
3480       ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate);
3481 
3482   // If we need to check for the named return value optimization,
3483   // or if we need to infer the return type,
3484   // save the return statement in our scope for later processing.
3485   if (CurCap->HasImplicitReturnType || NRVOCandidate)
3486     FunctionScopes.back()->Returns.push_back(Result);
3487 
3488   if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3489     FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3490 
3491   return Result;
3492 }
3493 
3494 namespace {
3495 /// Marks all typedefs in all local classes in a type referenced.
3496 ///
3497 /// In a function like
3498 /// auto f() {
3499 ///   struct S { typedef int a; };
3500 ///   return S();
3501 /// }
3502 ///
3503 /// the local type escapes and could be referenced in some TUs but not in
3504 /// others. Pretend that all local typedefs are always referenced, to not warn
3505 /// on this. This isn't necessary if f has internal linkage, or the typedef
3506 /// is private.
3507 class LocalTypedefNameReferencer
3508     : public RecursiveASTVisitor<LocalTypedefNameReferencer> {
3509 public:
3510   LocalTypedefNameReferencer(Sema &S) : S(S) {}
3511   bool VisitRecordType(const RecordType *RT);
3512 private:
3513   Sema &S;
3514 };
3515 bool LocalTypedefNameReferencer::VisitRecordType(const RecordType *RT) {
3516   auto *R = dyn_cast<CXXRecordDecl>(RT->getDecl());
3517   if (!R || !R->isLocalClass() || !R->isLocalClass()->isExternallyVisible() ||
3518       R->isDependentType())
3519     return true;
3520   for (auto *TmpD : R->decls())
3521     if (auto *T = dyn_cast<TypedefNameDecl>(TmpD))
3522       if (T->getAccess() != AS_private || R->hasFriends())
3523         S.MarkAnyDeclReferenced(T->getLocation(), T, /*OdrUse=*/false);
3524   return true;
3525 }
3526 }
3527 
3528 TypeLoc Sema::getReturnTypeLoc(FunctionDecl *FD) const {
3529   return FD->getTypeSourceInfo()
3530       ->getTypeLoc()
3531       .getAsAdjusted<FunctionProtoTypeLoc>()
3532       .getReturnLoc();
3533 }
3534 
3535 /// Deduce the return type for a function from a returned expression, per
3536 /// C++1y [dcl.spec.auto]p6.
3537 bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
3538                                             SourceLocation ReturnLoc,
3539                                             Expr *&RetExpr,
3540                                             AutoType *AT) {
3541   // If this is the conversion function for a lambda, we choose to deduce it
3542   // type from the corresponding call operator, not from the synthesized return
3543   // statement within it. See Sema::DeduceReturnType.
3544   if (isLambdaConversionOperator(FD))
3545     return false;
3546 
3547   TypeLoc OrigResultType = getReturnTypeLoc(FD);
3548   QualType Deduced;
3549 
3550   if (RetExpr && isa<InitListExpr>(RetExpr)) {
3551     //  If the deduction is for a return statement and the initializer is
3552     //  a braced-init-list, the program is ill-formed.
3553     Diag(RetExpr->getExprLoc(),
3554          getCurLambda() ? diag::err_lambda_return_init_list
3555                         : diag::err_auto_fn_return_init_list)
3556         << RetExpr->getSourceRange();
3557     return true;
3558   }
3559 
3560   if (FD->isDependentContext()) {
3561     // C++1y [dcl.spec.auto]p12:
3562     //   Return type deduction [...] occurs when the definition is
3563     //   instantiated even if the function body contains a return
3564     //   statement with a non-type-dependent operand.
3565     assert(AT->isDeduced() && "should have deduced to dependent type");
3566     return false;
3567   }
3568 
3569   if (RetExpr) {
3570     //  Otherwise, [...] deduce a value for U using the rules of template
3571     //  argument deduction.
3572     DeduceAutoResult DAR = DeduceAutoType(OrigResultType, RetExpr, Deduced);
3573 
3574     if (DAR == DAR_Failed && !FD->isInvalidDecl())
3575       Diag(RetExpr->getExprLoc(), diag::err_auto_fn_deduction_failure)
3576         << OrigResultType.getType() << RetExpr->getType();
3577 
3578     if (DAR != DAR_Succeeded)
3579       return true;
3580 
3581     // If a local type is part of the returned type, mark its fields as
3582     // referenced.
3583     LocalTypedefNameReferencer Referencer(*this);
3584     Referencer.TraverseType(RetExpr->getType());
3585   } else {
3586     //  In the case of a return with no operand, the initializer is considered
3587     //  to be void().
3588     //
3589     // Deduction here can only succeed if the return type is exactly 'cv auto'
3590     // or 'decltype(auto)', so just check for that case directly.
3591     if (!OrigResultType.getType()->getAs<AutoType>()) {
3592       Diag(ReturnLoc, diag::err_auto_fn_return_void_but_not_auto)
3593         << OrigResultType.getType();
3594       return true;
3595     }
3596     // We always deduce U = void in this case.
3597     Deduced = SubstAutoType(OrigResultType.getType(), Context.VoidTy);
3598     if (Deduced.isNull())
3599       return true;
3600   }
3601 
3602   // CUDA: Kernel function must have 'void' return type.
3603   if (getLangOpts().CUDA)
3604     if (FD->hasAttr<CUDAGlobalAttr>() && !Deduced->isVoidType()) {
3605       Diag(FD->getLocation(), diag::err_kern_type_not_void_return)
3606           << FD->getType() << FD->getSourceRange();
3607       return true;
3608     }
3609 
3610   //  If a function with a declared return type that contains a placeholder type
3611   //  has multiple return statements, the return type is deduced for each return
3612   //  statement. [...] if the type deduced is not the same in each deduction,
3613   //  the program is ill-formed.
3614   QualType DeducedT = AT->getDeducedType();
3615   if (!DeducedT.isNull() && !FD->isInvalidDecl()) {
3616     AutoType *NewAT = Deduced->getContainedAutoType();
3617     // It is possible that NewAT->getDeducedType() is null. When that happens,
3618     // we should not crash, instead we ignore this deduction.
3619     if (NewAT->getDeducedType().isNull())
3620       return false;
3621 
3622     CanQualType OldDeducedType = Context.getCanonicalFunctionResultType(
3623                                    DeducedT);
3624     CanQualType NewDeducedType = Context.getCanonicalFunctionResultType(
3625                                    NewAT->getDeducedType());
3626     if (!FD->isDependentContext() && OldDeducedType != NewDeducedType) {
3627       const LambdaScopeInfo *LambdaSI = getCurLambda();
3628       if (LambdaSI && LambdaSI->HasImplicitReturnType) {
3629         Diag(ReturnLoc, diag::err_typecheck_missing_return_type_incompatible)
3630           << NewAT->getDeducedType() << DeducedT
3631           << true /*IsLambda*/;
3632       } else {
3633         Diag(ReturnLoc, diag::err_auto_fn_different_deductions)
3634           << (AT->isDecltypeAuto() ? 1 : 0)
3635           << NewAT->getDeducedType() << DeducedT;
3636       }
3637       return true;
3638     }
3639   } else if (!FD->isInvalidDecl()) {
3640     // Update all declarations of the function to have the deduced return type.
3641     Context.adjustDeducedFunctionResultType(FD, Deduced);
3642   }
3643 
3644   return false;
3645 }
3646 
3647 StmtResult
3648 Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
3649                       Scope *CurScope) {
3650   // Correct typos, in case the containing function returns 'auto' and
3651   // RetValExp should determine the deduced type.
3652   ExprResult RetVal = CorrectDelayedTyposInExpr(
3653       RetValExp, nullptr, /*RecoverUncorrectedTypos=*/true);
3654   if (RetVal.isInvalid())
3655     return StmtError();
3656   StmtResult R = BuildReturnStmt(ReturnLoc, RetVal.get());
3657   if (R.isInvalid() || ExprEvalContexts.back().Context ==
3658                            ExpressionEvaluationContext::DiscardedStatement)
3659     return R;
3660 
3661   if (VarDecl *VD =
3662       const_cast<VarDecl*>(cast<ReturnStmt>(R.get())->getNRVOCandidate())) {
3663     CurScope->addNRVOCandidate(VD);
3664   } else {
3665     CurScope->setNoNRVO();
3666   }
3667 
3668   CheckJumpOutOfSEHFinally(*this, ReturnLoc, *CurScope->getFnParent());
3669 
3670   return R;
3671 }
3672 
3673 StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
3674   // Check for unexpanded parameter packs.
3675   if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp))
3676     return StmtError();
3677 
3678   if (isa<CapturingScopeInfo>(getCurFunction()))
3679     return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp);
3680 
3681   QualType FnRetType;
3682   QualType RelatedRetType;
3683   const AttrVec *Attrs = nullptr;
3684   bool isObjCMethod = false;
3685 
3686   if (const FunctionDecl *FD = getCurFunctionDecl()) {
3687     FnRetType = FD->getReturnType();
3688     if (FD->hasAttrs())
3689       Attrs = &FD->getAttrs();
3690     if (FD->isNoReturn())
3691       Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr) << FD;
3692     if (FD->isMain() && RetValExp)
3693       if (isa<CXXBoolLiteralExpr>(RetValExp))
3694         Diag(ReturnLoc, diag::warn_main_returns_bool_literal)
3695             << RetValExp->getSourceRange();
3696     if (FD->hasAttr<CmseNSEntryAttr>() && RetValExp) {
3697       if (const auto *RT = dyn_cast<RecordType>(FnRetType.getCanonicalType())) {
3698         if (RT->getDecl()->isOrContainsUnion())
3699           Diag(RetValExp->getBeginLoc(), diag::warn_cmse_nonsecure_union) << 1;
3700       }
3701     }
3702   } else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
3703     FnRetType = MD->getReturnType();
3704     isObjCMethod = true;
3705     if (MD->hasAttrs())
3706       Attrs = &MD->getAttrs();
3707     if (MD->hasRelatedResultType() && MD->getClassInterface()) {
3708       // In the implementation of a method with a related return type, the
3709       // type used to type-check the validity of return statements within the
3710       // method body is a pointer to the type of the class being implemented.
3711       RelatedRetType = Context.getObjCInterfaceType(MD->getClassInterface());
3712       RelatedRetType = Context.getObjCObjectPointerType(RelatedRetType);
3713     }
3714   } else // If we don't have a function/method context, bail.
3715     return StmtError();
3716 
3717   // C++1z: discarded return statements are not considered when deducing a
3718   // return type.
3719   if (ExprEvalContexts.back().Context ==
3720           ExpressionEvaluationContext::DiscardedStatement &&
3721       FnRetType->getContainedAutoType()) {
3722     if (RetValExp) {
3723       ExprResult ER =
3724           ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3725       if (ER.isInvalid())
3726         return StmtError();
3727       RetValExp = ER.get();
3728     }
3729     return ReturnStmt::Create(Context, ReturnLoc, RetValExp,
3730                               /* NRVOCandidate=*/nullptr);
3731   }
3732 
3733   // FIXME: Add a flag to the ScopeInfo to indicate whether we're performing
3734   // deduction.
3735   if (getLangOpts().CPlusPlus14) {
3736     if (AutoType *AT = FnRetType->getContainedAutoType()) {
3737       FunctionDecl *FD = cast<FunctionDecl>(CurContext);
3738       // If we've already decided this function is invalid, e.g. because
3739       // we saw a `return` whose expression had an error, don't keep
3740       // trying to deduce its return type.
3741       if (FD->isInvalidDecl())
3742         return StmtError();
3743       if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
3744         FD->setInvalidDecl();
3745         return StmtError();
3746       } else {
3747         FnRetType = FD->getReturnType();
3748       }
3749     }
3750   }
3751 
3752   bool HasDependentReturnType = FnRetType->isDependentType();
3753 
3754   ReturnStmt *Result = nullptr;
3755   if (FnRetType->isVoidType()) {
3756     if (RetValExp) {
3757       if (isa<InitListExpr>(RetValExp)) {
3758         // We simply never allow init lists as the return value of void
3759         // functions. This is compatible because this was never allowed before,
3760         // so there's no legacy code to deal with.
3761         NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3762         int FunctionKind = 0;
3763         if (isa<ObjCMethodDecl>(CurDecl))
3764           FunctionKind = 1;
3765         else if (isa<CXXConstructorDecl>(CurDecl))
3766           FunctionKind = 2;
3767         else if (isa<CXXDestructorDecl>(CurDecl))
3768           FunctionKind = 3;
3769 
3770         Diag(ReturnLoc, diag::err_return_init_list)
3771             << CurDecl << FunctionKind << RetValExp->getSourceRange();
3772 
3773         // Drop the expression.
3774         RetValExp = nullptr;
3775       } else if (!RetValExp->isTypeDependent()) {
3776         // C99 6.8.6.4p1 (ext_ since GCC warns)
3777         unsigned D = diag::ext_return_has_expr;
3778         if (RetValExp->getType()->isVoidType()) {
3779           NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3780           if (isa<CXXConstructorDecl>(CurDecl) ||
3781               isa<CXXDestructorDecl>(CurDecl))
3782             D = diag::err_ctor_dtor_returns_void;
3783           else
3784             D = diag::ext_return_has_void_expr;
3785         }
3786         else {
3787           ExprResult Result = RetValExp;
3788           Result = IgnoredValueConversions(Result.get());
3789           if (Result.isInvalid())
3790             return StmtError();
3791           RetValExp = Result.get();
3792           RetValExp = ImpCastExprToType(RetValExp,
3793                                         Context.VoidTy, CK_ToVoid).get();
3794         }
3795         // return of void in constructor/destructor is illegal in C++.
3796         if (D == diag::err_ctor_dtor_returns_void) {
3797           NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3798           Diag(ReturnLoc, D) << CurDecl << isa<CXXDestructorDecl>(CurDecl)
3799                              << RetValExp->getSourceRange();
3800         }
3801         // return (some void expression); is legal in C++.
3802         else if (D != diag::ext_return_has_void_expr ||
3803                  !getLangOpts().CPlusPlus) {
3804           NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3805 
3806           int FunctionKind = 0;
3807           if (isa<ObjCMethodDecl>(CurDecl))
3808             FunctionKind = 1;
3809           else if (isa<CXXConstructorDecl>(CurDecl))
3810             FunctionKind = 2;
3811           else if (isa<CXXDestructorDecl>(CurDecl))
3812             FunctionKind = 3;
3813 
3814           Diag(ReturnLoc, D)
3815               << CurDecl << FunctionKind << RetValExp->getSourceRange();
3816         }
3817       }
3818 
3819       if (RetValExp) {
3820         ExprResult ER =
3821             ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3822         if (ER.isInvalid())
3823           return StmtError();
3824         RetValExp = ER.get();
3825       }
3826     }
3827 
3828     Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp,
3829                                 /* NRVOCandidate=*/nullptr);
3830   } else if (!RetValExp && !HasDependentReturnType) {
3831     FunctionDecl *FD = getCurFunctionDecl();
3832 
3833     if (getLangOpts().CPlusPlus11 && FD && FD->isConstexpr()) {
3834       // C++11 [stmt.return]p2
3835       Diag(ReturnLoc, diag::err_constexpr_return_missing_expr)
3836           << FD << FD->isConsteval();
3837       FD->setInvalidDecl();
3838     } else {
3839       // C99 6.8.6.4p1 (ext_ since GCC warns)
3840       // C90 6.6.6.4p4
3841       unsigned DiagID = getLangOpts().C99 ? diag::ext_return_missing_expr
3842                                           : diag::warn_return_missing_expr;
3843       // Note that at this point one of getCurFunctionDecl() or
3844       // getCurMethodDecl() must be non-null (see above).
3845       assert((getCurFunctionDecl() || getCurMethodDecl()) &&
3846              "Not in a FunctionDecl or ObjCMethodDecl?");
3847       bool IsMethod = FD == nullptr;
3848       const NamedDecl *ND =
3849           IsMethod ? cast<NamedDecl>(getCurMethodDecl()) : cast<NamedDecl>(FD);
3850       Diag(ReturnLoc, DiagID) << ND << IsMethod;
3851     }
3852 
3853     Result = ReturnStmt::Create(Context, ReturnLoc, /* RetExpr=*/nullptr,
3854                                 /* NRVOCandidate=*/nullptr);
3855   } else {
3856     assert(RetValExp || HasDependentReturnType);
3857     const VarDecl *NRVOCandidate = nullptr;
3858 
3859     QualType RetType = RelatedRetType.isNull() ? FnRetType : RelatedRetType;
3860 
3861     // C99 6.8.6.4p3(136): The return statement is not an assignment. The
3862     // overlap restriction of subclause 6.5.16.1 does not apply to the case of
3863     // function return.
3864 
3865     // In C++ the return statement is handled via a copy initialization,
3866     // the C version of which boils down to CheckSingleAssignmentConstraints.
3867     if (RetValExp)
3868       NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
3869     if (!HasDependentReturnType && !RetValExp->isTypeDependent()) {
3870       // we have a non-void function with an expression, continue checking
3871       InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
3872                                                                      RetType,
3873                                                       NRVOCandidate != nullptr);
3874       ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
3875                                                        RetType, RetValExp);
3876       if (Res.isInvalid()) {
3877         // FIXME: Clean up temporaries here anyway?
3878         return StmtError();
3879       }
3880       RetValExp = Res.getAs<Expr>();
3881 
3882       // If we have a related result type, we need to implicitly
3883       // convert back to the formal result type.  We can't pretend to
3884       // initialize the result again --- we might end double-retaining
3885       // --- so instead we initialize a notional temporary.
3886       if (!RelatedRetType.isNull()) {
3887         Entity = InitializedEntity::InitializeRelatedResult(getCurMethodDecl(),
3888                                                             FnRetType);
3889         Res = PerformCopyInitialization(Entity, ReturnLoc, RetValExp);
3890         if (Res.isInvalid()) {
3891           // FIXME: Clean up temporaries here anyway?
3892           return StmtError();
3893         }
3894         RetValExp = Res.getAs<Expr>();
3895       }
3896 
3897       CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc, isObjCMethod, Attrs,
3898                          getCurFunctionDecl());
3899     }
3900 
3901     if (RetValExp) {
3902       ExprResult ER =
3903           ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3904       if (ER.isInvalid())
3905         return StmtError();
3906       RetValExp = ER.get();
3907     }
3908     Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate);
3909   }
3910 
3911   // If we need to check for the named return value optimization, save the
3912   // return statement in our scope for later processing.
3913   if (Result->getNRVOCandidate())
3914     FunctionScopes.back()->Returns.push_back(Result);
3915 
3916   if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3917     FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3918 
3919   return Result;
3920 }
3921 
3922 StmtResult
3923 Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
3924                            SourceLocation RParen, Decl *Parm,
3925                            Stmt *Body) {
3926   VarDecl *Var = cast_or_null<VarDecl>(Parm);
3927   if (Var && Var->isInvalidDecl())
3928     return StmtError();
3929 
3930   return new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body);
3931 }
3932 
3933 StmtResult
3934 Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
3935   return new (Context) ObjCAtFinallyStmt(AtLoc, Body);
3936 }
3937 
3938 StmtResult
3939 Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
3940                          MultiStmtArg CatchStmts, Stmt *Finally) {
3941   if (!getLangOpts().ObjCExceptions)
3942     Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@try";
3943 
3944   setFunctionHasBranchProtectedScope();
3945   unsigned NumCatchStmts = CatchStmts.size();
3946   return ObjCAtTryStmt::Create(Context, AtLoc, Try, CatchStmts.data(),
3947                                NumCatchStmts, Finally);
3948 }
3949 
3950 StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) {
3951   if (Throw) {
3952     ExprResult Result = DefaultLvalueConversion(Throw);
3953     if (Result.isInvalid())
3954       return StmtError();
3955 
3956     Result = ActOnFinishFullExpr(Result.get(), /*DiscardedValue*/ false);
3957     if (Result.isInvalid())
3958       return StmtError();
3959     Throw = Result.get();
3960 
3961     QualType ThrowType = Throw->getType();
3962     // Make sure the expression type is an ObjC pointer or "void *".
3963     if (!ThrowType->isDependentType() &&
3964         !ThrowType->isObjCObjectPointerType()) {
3965       const PointerType *PT = ThrowType->getAs<PointerType>();
3966       if (!PT || !PT->getPointeeType()->isVoidType())
3967         return StmtError(Diag(AtLoc, diag::err_objc_throw_expects_object)
3968                          << Throw->getType() << Throw->getSourceRange());
3969     }
3970   }
3971 
3972   return new (Context) ObjCAtThrowStmt(AtLoc, Throw);
3973 }
3974 
3975 StmtResult
3976 Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
3977                            Scope *CurScope) {
3978   if (!getLangOpts().ObjCExceptions)
3979     Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@throw";
3980 
3981   if (!Throw) {
3982     // @throw without an expression designates a rethrow (which must occur
3983     // in the context of an @catch clause).
3984     Scope *AtCatchParent = CurScope;
3985     while (AtCatchParent && !AtCatchParent->isAtCatchScope())
3986       AtCatchParent = AtCatchParent->getParent();
3987     if (!AtCatchParent)
3988       return StmtError(Diag(AtLoc, diag::err_rethrow_used_outside_catch));
3989   }
3990   return BuildObjCAtThrowStmt(AtLoc, Throw);
3991 }
3992 
3993 ExprResult
3994 Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
3995   ExprResult result = DefaultLvalueConversion(operand);
3996   if (result.isInvalid())
3997     return ExprError();
3998   operand = result.get();
3999 
4000   // Make sure the expression type is an ObjC pointer or "void *".
4001   QualType type = operand->getType();
4002   if (!type->isDependentType() &&
4003       !type->isObjCObjectPointerType()) {
4004     const PointerType *pointerType = type->getAs<PointerType>();
4005     if (!pointerType || !pointerType->getPointeeType()->isVoidType()) {
4006       if (getLangOpts().CPlusPlus) {
4007         if (RequireCompleteType(atLoc, type,
4008                                 diag::err_incomplete_receiver_type))
4009           return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4010                    << type << operand->getSourceRange();
4011 
4012         ExprResult result = PerformContextuallyConvertToObjCPointer(operand);
4013         if (result.isInvalid())
4014           return ExprError();
4015         if (!result.isUsable())
4016           return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4017                    << type << operand->getSourceRange();
4018 
4019         operand = result.get();
4020       } else {
4021           return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4022                    << type << operand->getSourceRange();
4023       }
4024     }
4025   }
4026 
4027   // The operand to @synchronized is a full-expression.
4028   return ActOnFinishFullExpr(operand, /*DiscardedValue*/ false);
4029 }
4030 
4031 StmtResult
4032 Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
4033                                   Stmt *SyncBody) {
4034   // We can't jump into or indirect-jump out of a @synchronized block.
4035   setFunctionHasBranchProtectedScope();
4036   return new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody);
4037 }
4038 
4039 /// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
4040 /// and creates a proper catch handler from them.
4041 StmtResult
4042 Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
4043                          Stmt *HandlerBlock) {
4044   // There's nothing to test that ActOnExceptionDecl didn't already test.
4045   return new (Context)
4046       CXXCatchStmt(CatchLoc, cast_or_null<VarDecl>(ExDecl), HandlerBlock);
4047 }
4048 
4049 StmtResult
4050 Sema::ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body) {
4051   setFunctionHasBranchProtectedScope();
4052   return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body);
4053 }
4054 
4055 namespace {
4056 class CatchHandlerType {
4057   QualType QT;
4058   unsigned IsPointer : 1;
4059 
4060   // This is a special constructor to be used only with DenseMapInfo's
4061   // getEmptyKey() and getTombstoneKey() functions.
4062   friend struct llvm::DenseMapInfo<CatchHandlerType>;
4063   enum Unique { ForDenseMap };
4064   CatchHandlerType(QualType QT, Unique) : QT(QT), IsPointer(false) {}
4065 
4066 public:
4067   /// Used when creating a CatchHandlerType from a handler type; will determine
4068   /// whether the type is a pointer or reference and will strip off the top
4069   /// level pointer and cv-qualifiers.
4070   CatchHandlerType(QualType Q) : QT(Q), IsPointer(false) {
4071     if (QT->isPointerType())
4072       IsPointer = true;
4073 
4074     if (IsPointer || QT->isReferenceType())
4075       QT = QT->getPointeeType();
4076     QT = QT.getUnqualifiedType();
4077   }
4078 
4079   /// Used when creating a CatchHandlerType from a base class type; pretends the
4080   /// type passed in had the pointer qualifier, does not need to get an
4081   /// unqualified type.
4082   CatchHandlerType(QualType QT, bool IsPointer)
4083       : QT(QT), IsPointer(IsPointer) {}
4084 
4085   QualType underlying() const { return QT; }
4086   bool isPointer() const { return IsPointer; }
4087 
4088   friend bool operator==(const CatchHandlerType &LHS,
4089                          const CatchHandlerType &RHS) {
4090     // If the pointer qualification does not match, we can return early.
4091     if (LHS.IsPointer != RHS.IsPointer)
4092       return false;
4093     // Otherwise, check the underlying type without cv-qualifiers.
4094     return LHS.QT == RHS.QT;
4095   }
4096 };
4097 } // namespace
4098 
4099 namespace llvm {
4100 template <> struct DenseMapInfo<CatchHandlerType> {
4101   static CatchHandlerType getEmptyKey() {
4102     return CatchHandlerType(DenseMapInfo<QualType>::getEmptyKey(),
4103                        CatchHandlerType::ForDenseMap);
4104   }
4105 
4106   static CatchHandlerType getTombstoneKey() {
4107     return CatchHandlerType(DenseMapInfo<QualType>::getTombstoneKey(),
4108                        CatchHandlerType::ForDenseMap);
4109   }
4110 
4111   static unsigned getHashValue(const CatchHandlerType &Base) {
4112     return DenseMapInfo<QualType>::getHashValue(Base.underlying());
4113   }
4114 
4115   static bool isEqual(const CatchHandlerType &LHS,
4116                       const CatchHandlerType &RHS) {
4117     return LHS == RHS;
4118   }
4119 };
4120 }
4121 
4122 namespace {
4123 class CatchTypePublicBases {
4124   ASTContext &Ctx;
4125   const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &TypesToCheck;
4126   const bool CheckAgainstPointer;
4127 
4128   CXXCatchStmt *FoundHandler;
4129   CanQualType FoundHandlerType;
4130 
4131 public:
4132   CatchTypePublicBases(
4133       ASTContext &Ctx,
4134       const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &T, bool C)
4135       : Ctx(Ctx), TypesToCheck(T), CheckAgainstPointer(C),
4136         FoundHandler(nullptr) {}
4137 
4138   CXXCatchStmt *getFoundHandler() const { return FoundHandler; }
4139   CanQualType getFoundHandlerType() const { return FoundHandlerType; }
4140 
4141   bool operator()(const CXXBaseSpecifier *S, CXXBasePath &) {
4142     if (S->getAccessSpecifier() == AccessSpecifier::AS_public) {
4143       CatchHandlerType Check(S->getType(), CheckAgainstPointer);
4144       const auto &M = TypesToCheck;
4145       auto I = M.find(Check);
4146       if (I != M.end()) {
4147         FoundHandler = I->second;
4148         FoundHandlerType = Ctx.getCanonicalType(S->getType());
4149         return true;
4150       }
4151     }
4152     return false;
4153   }
4154 };
4155 }
4156 
4157 /// ActOnCXXTryBlock - Takes a try compound-statement and a number of
4158 /// handlers and creates a try statement from them.
4159 StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
4160                                   ArrayRef<Stmt *> Handlers) {
4161   // Don't report an error if 'try' is used in system headers.
4162   if (!getLangOpts().CXXExceptions &&
4163       !getSourceManager().isInSystemHeader(TryLoc) && !getLangOpts().CUDA) {
4164     // Delay error emission for the OpenMP device code.
4165     targetDiag(TryLoc, diag::err_exceptions_disabled) << "try";
4166   }
4167 
4168   // Exceptions aren't allowed in CUDA device code.
4169   if (getLangOpts().CUDA)
4170     CUDADiagIfDeviceCode(TryLoc, diag::err_cuda_device_exceptions)
4171         << "try" << CurrentCUDATarget();
4172 
4173   if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope())
4174     Diag(TryLoc, diag::err_omp_simd_region_cannot_use_stmt) << "try";
4175 
4176   sema::FunctionScopeInfo *FSI = getCurFunction();
4177 
4178   // C++ try is incompatible with SEH __try.
4179   if (!getLangOpts().Borland && FSI->FirstSEHTryLoc.isValid()) {
4180     Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
4181     Diag(FSI->FirstSEHTryLoc, diag::note_conflicting_try_here) << "'__try'";
4182   }
4183 
4184   const unsigned NumHandlers = Handlers.size();
4185   assert(!Handlers.empty() &&
4186          "The parser shouldn't call this if there are no handlers.");
4187 
4188   llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> HandledTypes;
4189   for (unsigned i = 0; i < NumHandlers; ++i) {
4190     CXXCatchStmt *H = cast<CXXCatchStmt>(Handlers[i]);
4191 
4192     // Diagnose when the handler is a catch-all handler, but it isn't the last
4193     // handler for the try block. [except.handle]p5. Also, skip exception
4194     // declarations that are invalid, since we can't usefully report on them.
4195     if (!H->getExceptionDecl()) {
4196       if (i < NumHandlers - 1)
4197         return StmtError(Diag(H->getBeginLoc(), diag::err_early_catch_all));
4198       continue;
4199     } else if (H->getExceptionDecl()->isInvalidDecl())
4200       continue;
4201 
4202     // Walk the type hierarchy to diagnose when this type has already been
4203     // handled (duplication), or cannot be handled (derivation inversion). We
4204     // ignore top-level cv-qualifiers, per [except.handle]p3
4205     CatchHandlerType HandlerCHT =
4206         (QualType)Context.getCanonicalType(H->getCaughtType());
4207 
4208     // We can ignore whether the type is a reference or a pointer; we need the
4209     // underlying declaration type in order to get at the underlying record
4210     // decl, if there is one.
4211     QualType Underlying = HandlerCHT.underlying();
4212     if (auto *RD = Underlying->getAsCXXRecordDecl()) {
4213       if (!RD->hasDefinition())
4214         continue;
4215       // Check that none of the public, unambiguous base classes are in the
4216       // map ([except.handle]p1). Give the base classes the same pointer
4217       // qualification as the original type we are basing off of. This allows
4218       // comparison against the handler type using the same top-level pointer
4219       // as the original type.
4220       CXXBasePaths Paths;
4221       Paths.setOrigin(RD);
4222       CatchTypePublicBases CTPB(Context, HandledTypes, HandlerCHT.isPointer());
4223       if (RD->lookupInBases(CTPB, Paths)) {
4224         const CXXCatchStmt *Problem = CTPB.getFoundHandler();
4225         if (!Paths.isAmbiguous(CTPB.getFoundHandlerType())) {
4226           Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
4227                diag::warn_exception_caught_by_earlier_handler)
4228               << H->getCaughtType();
4229           Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
4230                 diag::note_previous_exception_handler)
4231               << Problem->getCaughtType();
4232         }
4233       }
4234     }
4235 
4236     // Add the type the list of ones we have handled; diagnose if we've already
4237     // handled it.
4238     auto R = HandledTypes.insert(std::make_pair(H->getCaughtType(), H));
4239     if (!R.second) {
4240       const CXXCatchStmt *Problem = R.first->second;
4241       Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
4242            diag::warn_exception_caught_by_earlier_handler)
4243           << H->getCaughtType();
4244       Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
4245            diag::note_previous_exception_handler)
4246           << Problem->getCaughtType();
4247     }
4248   }
4249 
4250   FSI->setHasCXXTry(TryLoc);
4251 
4252   return CXXTryStmt::Create(Context, TryLoc, TryBlock, Handlers);
4253 }
4254 
4255 StmtResult Sema::ActOnSEHTryBlock(bool IsCXXTry, SourceLocation TryLoc,
4256                                   Stmt *TryBlock, Stmt *Handler) {
4257   assert(TryBlock && Handler);
4258 
4259   sema::FunctionScopeInfo *FSI = getCurFunction();
4260 
4261   // SEH __try is incompatible with C++ try. Borland appears to support this,
4262   // however.
4263   if (!getLangOpts().Borland) {
4264     if (FSI->FirstCXXTryLoc.isValid()) {
4265       Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
4266       Diag(FSI->FirstCXXTryLoc, diag::note_conflicting_try_here) << "'try'";
4267     }
4268   }
4269 
4270   FSI->setHasSEHTry(TryLoc);
4271 
4272   // Reject __try in Obj-C methods, blocks, and captured decls, since we don't
4273   // track if they use SEH.
4274   DeclContext *DC = CurContext;
4275   while (DC && !DC->isFunctionOrMethod())
4276     DC = DC->getParent();
4277   FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(DC);
4278   if (FD)
4279     FD->setUsesSEHTry(true);
4280   else
4281     Diag(TryLoc, diag::err_seh_try_outside_functions);
4282 
4283   // Reject __try on unsupported targets.
4284   if (!Context.getTargetInfo().isSEHTrySupported())
4285     Diag(TryLoc, diag::err_seh_try_unsupported);
4286 
4287   return SEHTryStmt::Create(Context, IsCXXTry, TryLoc, TryBlock, Handler);
4288 }
4289 
4290 StmtResult Sema::ActOnSEHExceptBlock(SourceLocation Loc, Expr *FilterExpr,
4291                                      Stmt *Block) {
4292   assert(FilterExpr && Block);
4293   QualType FTy = FilterExpr->getType();
4294   if (!FTy->isIntegerType() && !FTy->isDependentType()) {
4295     return StmtError(
4296         Diag(FilterExpr->getExprLoc(), diag::err_filter_expression_integral)
4297         << FTy);
4298   }
4299   return SEHExceptStmt::Create(Context, Loc, FilterExpr, Block);
4300 }
4301 
4302 void Sema::ActOnStartSEHFinallyBlock() {
4303   CurrentSEHFinally.push_back(CurScope);
4304 }
4305 
4306 void Sema::ActOnAbortSEHFinallyBlock() {
4307   CurrentSEHFinally.pop_back();
4308 }
4309 
4310 StmtResult Sema::ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block) {
4311   assert(Block);
4312   CurrentSEHFinally.pop_back();
4313   return SEHFinallyStmt::Create(Context, Loc, Block);
4314 }
4315 
4316 StmtResult
4317 Sema::ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope) {
4318   Scope *SEHTryParent = CurScope;
4319   while (SEHTryParent && !SEHTryParent->isSEHTryScope())
4320     SEHTryParent = SEHTryParent->getParent();
4321   if (!SEHTryParent)
4322     return StmtError(Diag(Loc, diag::err_ms___leave_not_in___try));
4323   CheckJumpOutOfSEHFinally(*this, Loc, *SEHTryParent);
4324 
4325   return new (Context) SEHLeaveStmt(Loc);
4326 }
4327 
4328 StmtResult Sema::BuildMSDependentExistsStmt(SourceLocation KeywordLoc,
4329                                             bool IsIfExists,
4330                                             NestedNameSpecifierLoc QualifierLoc,
4331                                             DeclarationNameInfo NameInfo,
4332                                             Stmt *Nested)
4333 {
4334   return new (Context) MSDependentExistsStmt(KeywordLoc, IsIfExists,
4335                                              QualifierLoc, NameInfo,
4336                                              cast<CompoundStmt>(Nested));
4337 }
4338 
4339 
4340 StmtResult Sema::ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,
4341                                             bool IsIfExists,
4342                                             CXXScopeSpec &SS,
4343                                             UnqualifiedId &Name,
4344                                             Stmt *Nested) {
4345   return BuildMSDependentExistsStmt(KeywordLoc, IsIfExists,
4346                                     SS.getWithLocInContext(Context),
4347                                     GetNameFromUnqualifiedId(Name),
4348                                     Nested);
4349 }
4350 
4351 RecordDecl*
4352 Sema::CreateCapturedStmtRecordDecl(CapturedDecl *&CD, SourceLocation Loc,
4353                                    unsigned NumParams) {
4354   DeclContext *DC = CurContext;
4355   while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
4356     DC = DC->getParent();
4357 
4358   RecordDecl *RD = nullptr;
4359   if (getLangOpts().CPlusPlus)
4360     RD = CXXRecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc,
4361                                /*Id=*/nullptr);
4362   else
4363     RD = RecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc, /*Id=*/nullptr);
4364 
4365   RD->setCapturedRecord();
4366   DC->addDecl(RD);
4367   RD->setImplicit();
4368   RD->startDefinition();
4369 
4370   assert(NumParams > 0 && "CapturedStmt requires context parameter");
4371   CD = CapturedDecl::Create(Context, CurContext, NumParams);
4372   DC->addDecl(CD);
4373   return RD;
4374 }
4375 
4376 static bool
4377 buildCapturedStmtCaptureList(Sema &S, CapturedRegionScopeInfo *RSI,
4378                              SmallVectorImpl<CapturedStmt::Capture> &Captures,
4379                              SmallVectorImpl<Expr *> &CaptureInits) {
4380   for (const sema::Capture &Cap : RSI->Captures) {
4381     if (Cap.isInvalid())
4382       continue;
4383 
4384     // Form the initializer for the capture.
4385     ExprResult Init = S.BuildCaptureInit(Cap, Cap.getLocation(),
4386                                          RSI->CapRegionKind == CR_OpenMP);
4387 
4388     // FIXME: Bail out now if the capture is not used and the initializer has
4389     // no side-effects.
4390 
4391     // Create a field for this capture.
4392     FieldDecl *Field = S.BuildCaptureField(RSI->TheRecordDecl, Cap);
4393 
4394     // Add the capture to our list of captures.
4395     if (Cap.isThisCapture()) {
4396       Captures.push_back(CapturedStmt::Capture(Cap.getLocation(),
4397                                                CapturedStmt::VCK_This));
4398     } else if (Cap.isVLATypeCapture()) {
4399       Captures.push_back(
4400           CapturedStmt::Capture(Cap.getLocation(), CapturedStmt::VCK_VLAType));
4401     } else {
4402       assert(Cap.isVariableCapture() && "unknown kind of capture");
4403 
4404       if (S.getLangOpts().OpenMP && RSI->CapRegionKind == CR_OpenMP)
4405         S.setOpenMPCaptureKind(Field, Cap.getVariable(), RSI->OpenMPLevel);
4406 
4407       Captures.push_back(CapturedStmt::Capture(Cap.getLocation(),
4408                                                Cap.isReferenceCapture()
4409                                                    ? CapturedStmt::VCK_ByRef
4410                                                    : CapturedStmt::VCK_ByCopy,
4411                                                Cap.getVariable()));
4412     }
4413     CaptureInits.push_back(Init.get());
4414   }
4415   return false;
4416 }
4417 
4418 void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
4419                                     CapturedRegionKind Kind,
4420                                     unsigned NumParams) {
4421   CapturedDecl *CD = nullptr;
4422   RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, NumParams);
4423 
4424   // Build the context parameter
4425   DeclContext *DC = CapturedDecl::castToDeclContext(CD);
4426   IdentifierInfo *ParamName = &Context.Idents.get("__context");
4427   QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
4428   auto *Param =
4429       ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType,
4430                                 ImplicitParamDecl::CapturedContext);
4431   DC->addDecl(Param);
4432 
4433   CD->setContextParam(0, Param);
4434 
4435   // Enter the capturing scope for this captured region.
4436   PushCapturedRegionScope(CurScope, CD, RD, Kind);
4437 
4438   if (CurScope)
4439     PushDeclContext(CurScope, CD);
4440   else
4441     CurContext = CD;
4442 
4443   PushExpressionEvaluationContext(
4444       ExpressionEvaluationContext::PotentiallyEvaluated);
4445 }
4446 
4447 void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
4448                                     CapturedRegionKind Kind,
4449                                     ArrayRef<CapturedParamNameType> Params,
4450                                     unsigned OpenMPCaptureLevel) {
4451   CapturedDecl *CD = nullptr;
4452   RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, Params.size());
4453 
4454   // Build the context parameter
4455   DeclContext *DC = CapturedDecl::castToDeclContext(CD);
4456   bool ContextIsFound = false;
4457   unsigned ParamNum = 0;
4458   for (ArrayRef<CapturedParamNameType>::iterator I = Params.begin(),
4459                                                  E = Params.end();
4460        I != E; ++I, ++ParamNum) {
4461     if (I->second.isNull()) {
4462       assert(!ContextIsFound &&
4463              "null type has been found already for '__context' parameter");
4464       IdentifierInfo *ParamName = &Context.Idents.get("__context");
4465       QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD))
4466                                .withConst()
4467                                .withRestrict();
4468       auto *Param =
4469           ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType,
4470                                     ImplicitParamDecl::CapturedContext);
4471       DC->addDecl(Param);
4472       CD->setContextParam(ParamNum, Param);
4473       ContextIsFound = true;
4474     } else {
4475       IdentifierInfo *ParamName = &Context.Idents.get(I->first);
4476       auto *Param =
4477           ImplicitParamDecl::Create(Context, DC, Loc, ParamName, I->second,
4478                                     ImplicitParamDecl::CapturedContext);
4479       DC->addDecl(Param);
4480       CD->setParam(ParamNum, Param);
4481     }
4482   }
4483   assert(ContextIsFound && "no null type for '__context' parameter");
4484   if (!ContextIsFound) {
4485     // Add __context implicitly if it is not specified.
4486     IdentifierInfo *ParamName = &Context.Idents.get("__context");
4487     QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
4488     auto *Param =
4489         ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType,
4490                                   ImplicitParamDecl::CapturedContext);
4491     DC->addDecl(Param);
4492     CD->setContextParam(ParamNum, Param);
4493   }
4494   // Enter the capturing scope for this captured region.
4495   PushCapturedRegionScope(CurScope, CD, RD, Kind, OpenMPCaptureLevel);
4496 
4497   if (CurScope)
4498     PushDeclContext(CurScope, CD);
4499   else
4500     CurContext = CD;
4501 
4502   PushExpressionEvaluationContext(
4503       ExpressionEvaluationContext::PotentiallyEvaluated);
4504 }
4505 
4506 void Sema::ActOnCapturedRegionError() {
4507   DiscardCleanupsInEvaluationContext();
4508   PopExpressionEvaluationContext();
4509   PopDeclContext();
4510   PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo();
4511   CapturedRegionScopeInfo *RSI = cast<CapturedRegionScopeInfo>(ScopeRAII.get());
4512 
4513   RecordDecl *Record = RSI->TheRecordDecl;
4514   Record->setInvalidDecl();
4515 
4516   SmallVector<Decl*, 4> Fields(Record->fields());
4517   ActOnFields(/*Scope=*/nullptr, Record->getLocation(), Record, Fields,
4518               SourceLocation(), SourceLocation(), ParsedAttributesView());
4519 }
4520 
4521 StmtResult Sema::ActOnCapturedRegionEnd(Stmt *S) {
4522   // Leave the captured scope before we start creating captures in the
4523   // enclosing scope.
4524   DiscardCleanupsInEvaluationContext();
4525   PopExpressionEvaluationContext();
4526   PopDeclContext();
4527   PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo();
4528   CapturedRegionScopeInfo *RSI = cast<CapturedRegionScopeInfo>(ScopeRAII.get());
4529 
4530   SmallVector<CapturedStmt::Capture, 4> Captures;
4531   SmallVector<Expr *, 4> CaptureInits;
4532   if (buildCapturedStmtCaptureList(*this, RSI, Captures, CaptureInits))
4533     return StmtError();
4534 
4535   CapturedDecl *CD = RSI->TheCapturedDecl;
4536   RecordDecl *RD = RSI->TheRecordDecl;
4537 
4538   CapturedStmt *Res = CapturedStmt::Create(
4539       getASTContext(), S, static_cast<CapturedRegionKind>(RSI->CapRegionKind),
4540       Captures, CaptureInits, CD, RD);
4541 
4542   CD->setBody(Res->getCapturedStmt());
4543   RD->completeDefinition();
4544 
4545   return Res;
4546 }
4547