1 //===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file implements semantic analysis for statements.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Sema/SemaInternal.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/ASTDiagnostic.h"
17 #include "clang/AST/CharUnits.h"
18 #include "clang/AST/CXXInheritance.h"
19 #include "clang/AST/DeclObjC.h"
20 #include "clang/AST/EvaluatedExprVisitor.h"
21 #include "clang/AST/ExprCXX.h"
22 #include "clang/AST/ExprObjC.h"
23 #include "clang/AST/RecursiveASTVisitor.h"
24 #include "clang/AST/StmtCXX.h"
25 #include "clang/AST/StmtObjC.h"
26 #include "clang/AST/TypeLoc.h"
27 #include "clang/AST/TypeOrdering.h"
28 #include "clang/Basic/TargetInfo.h"
29 #include "clang/Lex/Preprocessor.h"
30 #include "clang/Sema/Initialization.h"
31 #include "clang/Sema/Lookup.h"
32 #include "clang/Sema/Scope.h"
33 #include "clang/Sema/ScopeInfo.h"
34 #include "llvm/ADT/ArrayRef.h"
35 #include "llvm/ADT/DenseMap.h"
36 #include "llvm/ADT/STLExtras.h"
37 #include "llvm/ADT/SmallPtrSet.h"
38 #include "llvm/ADT/SmallString.h"
39 #include "llvm/ADT/SmallVector.h"
40 
41 using namespace clang;
42 using namespace sema;
43 
ActOnExprStmt(ExprResult FE)44 StmtResult Sema::ActOnExprStmt(ExprResult FE) {
45   if (FE.isInvalid())
46     return StmtError();
47 
48   FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(),
49                            /*DiscardedValue*/ true);
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 
ActOnExprStmtError()62 StmtResult Sema::ActOnExprStmtError() {
63   DiscardCleanupsInEvaluationContext();
64   return StmtError();
65 }
66 
ActOnNullStmt(SourceLocation SemiLoc,bool HasLeadingEmptyMacro)67 StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc,
68                                bool HasLeadingEmptyMacro) {
69   return new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro);
70 }
71 
ActOnDeclStmt(DeclGroupPtrTy dg,SourceLocation StartLoc,SourceLocation EndLoc)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 
ActOnForEachDeclStmt(DeclGroupPtrTy dg)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 /// \brief 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.
DiagnoseUnusedComparison(Sema & S,const Expr * E)128 static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) {
129   SourceLocation Loc;
130   bool IsNotEqual, CanAssign, IsRelational;
131 
132   if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
133     if (!Op->isComparisonOp())
134       return false;
135 
136     IsRelational = Op->isRelationalOp();
137     Loc = Op->getOperatorLoc();
138     IsNotEqual = Op->getOpcode() == BO_NE;
139     CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
140   } else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
141     switch (Op->getOperator()) {
142     default:
143       return false;
144     case OO_EqualEqual:
145     case OO_ExclaimEqual:
146       IsRelational = false;
147       break;
148     case OO_Less:
149     case OO_Greater:
150     case OO_GreaterEqual:
151     case OO_LessEqual:
152       IsRelational = true;
153       break;
154     }
155 
156     Loc = Op->getOperatorLoc();
157     IsNotEqual = Op->getOperator() == OO_ExclaimEqual;
158     CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
159   } else {
160     // Not a typo-prone comparison.
161     return false;
162   }
163 
164   // Suppress warnings when the operator, suspicious as it may be, comes from
165   // a macro expansion.
166   if (S.SourceMgr.isMacroBodyExpansion(Loc))
167     return false;
168 
169   S.Diag(Loc, diag::warn_unused_comparison)
170     << (unsigned)IsRelational << (unsigned)IsNotEqual << E->getSourceRange();
171 
172   // If the LHS is a plausible entity to assign to, provide a fixit hint to
173   // correct common typos.
174   if (!IsRelational && CanAssign) {
175     if (IsNotEqual)
176       S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
177         << FixItHint::CreateReplacement(Loc, "|=");
178     else
179       S.Diag(Loc, diag::note_equality_comparison_to_assign)
180         << FixItHint::CreateReplacement(Loc, "=");
181   }
182 
183   return true;
184 }
185 
DiagnoseUnusedExprResult(const Stmt * S)186 void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
187   if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
188     return DiagnoseUnusedExprResult(Label->getSubStmt());
189 
190   const Expr *E = dyn_cast_or_null<Expr>(S);
191   if (!E)
192     return;
193 
194   // If we are in an unevaluated expression context, then there can be no unused
195   // results because the results aren't expected to be used in the first place.
196   if (isUnevaluatedContext())
197     return;
198 
199   SourceLocation ExprLoc = E->IgnoreParenImpCasts()->getExprLoc();
200   // In most cases, we don't want to warn if the expression is written in a
201   // macro body, or if the macro comes from a system header. If the offending
202   // expression is a call to a function with the warn_unused_result attribute,
203   // we warn no matter the location. Because of the order in which the various
204   // checks need to happen, we factor out the macro-related test here.
205   bool ShouldSuppress =
206       SourceMgr.isMacroBodyExpansion(ExprLoc) ||
207       SourceMgr.isInSystemMacro(ExprLoc);
208 
209   const Expr *WarnExpr;
210   SourceLocation Loc;
211   SourceRange R1, R2;
212   if (!E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context))
213     return;
214 
215   // If this is a GNU statement expression expanded from a macro, it is probably
216   // unused because it is a function-like macro that can be used as either an
217   // expression or statement.  Don't warn, because it is almost certainly a
218   // false positive.
219   if (isa<StmtExpr>(E) && Loc.isMacroID())
220     return;
221 
222   // Check if this is the UNREFERENCED_PARAMETER from the Microsoft headers.
223   // That macro is frequently used to suppress "unused parameter" warnings,
224   // but its implementation makes clang's -Wunused-value fire.  Prevent this.
225   if (isa<ParenExpr>(E->IgnoreImpCasts()) && Loc.isMacroID()) {
226     SourceLocation SpellLoc = Loc;
227     if (findMacroSpelling(SpellLoc, "UNREFERENCED_PARAMETER"))
228       return;
229   }
230 
231   // Okay, we have an unused result.  Depending on what the base expression is,
232   // we might want to make a more specific diagnostic.  Check for one of these
233   // cases now.
234   unsigned DiagID = diag::warn_unused_expr;
235   if (const ExprWithCleanups *Temps = dyn_cast<ExprWithCleanups>(E))
236     E = Temps->getSubExpr();
237   if (const CXXBindTemporaryExpr *TempExpr = dyn_cast<CXXBindTemporaryExpr>(E))
238     E = TempExpr->getSubExpr();
239 
240   if (DiagnoseUnusedComparison(*this, E))
241     return;
242 
243   E = WarnExpr;
244   if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
245     if (E->getType()->isVoidType())
246       return;
247 
248     // If the callee has attribute pure, const, or warn_unused_result, warn with
249     // a more specific message to make it clear what is happening. If the call
250     // is written in a macro body, only warn if it has the warn_unused_result
251     // attribute.
252     if (const Decl *FD = CE->getCalleeDecl()) {
253       if (const Attr *A = isa<FunctionDecl>(FD)
254                               ? cast<FunctionDecl>(FD)->getUnusedResultAttr()
255                               : FD->getAttr<WarnUnusedResultAttr>()) {
256         Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
257         return;
258       }
259       if (ShouldSuppress)
260         return;
261       if (FD->hasAttr<PureAttr>()) {
262         Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
263         return;
264       }
265       if (FD->hasAttr<ConstAttr>()) {
266         Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
267         return;
268       }
269     }
270   } else if (ShouldSuppress)
271     return;
272 
273   if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
274     if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) {
275       Diag(Loc, diag::err_arc_unused_init_message) << R1;
276       return;
277     }
278     const ObjCMethodDecl *MD = ME->getMethodDecl();
279     if (MD) {
280       if (const auto *A = MD->getAttr<WarnUnusedResultAttr>()) {
281         Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
282         return;
283       }
284     }
285   } else if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
286     const Expr *Source = POE->getSyntacticForm();
287     if (isa<ObjCSubscriptRefExpr>(Source))
288       DiagID = diag::warn_unused_container_subscript_expr;
289     else
290       DiagID = diag::warn_unused_property_expr;
291   } else if (const CXXFunctionalCastExpr *FC
292                                        = dyn_cast<CXXFunctionalCastExpr>(E)) {
293     if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
294         isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
295       return;
296   }
297   // Diagnose "(void*) blah" as a typo for "(void) blah".
298   else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
299     TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
300     QualType T = TI->getType();
301 
302     // We really do want to use the non-canonical type here.
303     if (T == Context.VoidPtrTy) {
304       PointerTypeLoc TL = TI->getTypeLoc().castAs<PointerTypeLoc>();
305 
306       Diag(Loc, diag::warn_unused_voidptr)
307         << FixItHint::CreateRemoval(TL.getStarLoc());
308       return;
309     }
310   }
311 
312   if (E->isGLValue() && E->getType().isVolatileQualified()) {
313     Diag(Loc, diag::warn_unused_volatile) << R1 << R2;
314     return;
315   }
316 
317   DiagRuntimeBehavior(Loc, nullptr, PDiag(DiagID) << R1 << R2);
318 }
319 
ActOnStartOfCompoundStmt()320 void Sema::ActOnStartOfCompoundStmt() {
321   PushCompoundScope();
322 }
323 
ActOnFinishOfCompoundStmt()324 void Sema::ActOnFinishOfCompoundStmt() {
325   PopCompoundScope();
326 }
327 
getCurCompoundScope() const328 sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
329   return getCurFunction()->CompoundScopes.back();
330 }
331 
ActOnCompoundStmt(SourceLocation L,SourceLocation R,ArrayRef<Stmt * > Elts,bool isStmtExpr)332 StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
333                                    ArrayRef<Stmt *> Elts, bool isStmtExpr) {
334   const unsigned NumElts = Elts.size();
335 
336   // If we're in C89 mode, check that we don't have any decls after stmts.  If
337   // so, emit an extension diagnostic.
338   if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
339     // Note that __extension__ can be around a decl.
340     unsigned i = 0;
341     // Skip over all declarations.
342     for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
343       /*empty*/;
344 
345     // We found the end of the list or a statement.  Scan for another declstmt.
346     for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
347       /*empty*/;
348 
349     if (i != NumElts) {
350       Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
351       Diag(D->getLocation(), diag::ext_mixed_decls_code);
352     }
353   }
354   // Warn about unused expressions in statements.
355   for (unsigned i = 0; i != NumElts; ++i) {
356     // Ignore statements that are last in a statement expression.
357     if (isStmtExpr && i == NumElts - 1)
358       continue;
359 
360     DiagnoseUnusedExprResult(Elts[i]);
361   }
362 
363   // Check for suspicious empty body (null statement) in `for' and `while'
364   // statements.  Don't do anything for template instantiations, this just adds
365   // noise.
366   if (NumElts != 0 && !CurrentInstantiationScope &&
367       getCurCompoundScope().HasEmptyLoopBodies) {
368     for (unsigned i = 0; i != NumElts - 1; ++i)
369       DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]);
370   }
371 
372   return new (Context) CompoundStmt(Context, Elts, L, R);
373 }
374 
375 StmtResult
ActOnCaseStmt(SourceLocation CaseLoc,Expr * LHSVal,SourceLocation DotDotDotLoc,Expr * RHSVal,SourceLocation ColonLoc)376 Sema::ActOnCaseStmt(SourceLocation CaseLoc, Expr *LHSVal,
377                     SourceLocation DotDotDotLoc, Expr *RHSVal,
378                     SourceLocation ColonLoc) {
379   assert(LHSVal && "missing expression in case statement");
380 
381   if (getCurFunction()->SwitchStack.empty()) {
382     Diag(CaseLoc, diag::err_case_not_in_switch);
383     return StmtError();
384   }
385 
386   ExprResult LHS =
387       CorrectDelayedTyposInExpr(LHSVal, [this](class Expr *E) {
388         if (!getLangOpts().CPlusPlus11)
389           return VerifyIntegerConstantExpression(E);
390         if (Expr *CondExpr =
391                 getCurFunction()->SwitchStack.back()->getCond()) {
392           QualType CondType = CondExpr->getType();
393           llvm::APSInt TempVal;
394           return CheckConvertedConstantExpression(E, CondType, TempVal,
395                                                         CCEK_CaseValue);
396         }
397         return ExprError();
398       });
399   if (LHS.isInvalid())
400     return StmtError();
401   LHSVal = LHS.get();
402 
403   if (!getLangOpts().CPlusPlus11) {
404     // C99 6.8.4.2p3: The expression shall be an integer constant.
405     // However, GCC allows any evaluatable integer expression.
406     if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent()) {
407       LHSVal = VerifyIntegerConstantExpression(LHSVal).get();
408       if (!LHSVal)
409         return StmtError();
410     }
411 
412     // GCC extension: The expression shall be an integer constant.
413 
414     if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent()) {
415       RHSVal = VerifyIntegerConstantExpression(RHSVal).get();
416       // Recover from an error by just forgetting about it.
417     }
418   }
419 
420   LHS = ActOnFinishFullExpr(LHSVal, LHSVal->getExprLoc(), false,
421                                  getLangOpts().CPlusPlus11);
422   if (LHS.isInvalid())
423     return StmtError();
424 
425   auto RHS = RHSVal ? ActOnFinishFullExpr(RHSVal, RHSVal->getExprLoc(), false,
426                                           getLangOpts().CPlusPlus11)
427                     : ExprResult();
428   if (RHS.isInvalid())
429     return StmtError();
430 
431   CaseStmt *CS = new (Context)
432       CaseStmt(LHS.get(), RHS.get(), CaseLoc, DotDotDotLoc, ColonLoc);
433   getCurFunction()->SwitchStack.back()->addSwitchCase(CS);
434   return CS;
435 }
436 
437 /// ActOnCaseStmtBody - This installs a statement as the body of a case.
ActOnCaseStmtBody(Stmt * caseStmt,Stmt * SubStmt)438 void Sema::ActOnCaseStmtBody(Stmt *caseStmt, Stmt *SubStmt) {
439   DiagnoseUnusedExprResult(SubStmt);
440 
441   CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
442   CS->setSubStmt(SubStmt);
443 }
444 
445 StmtResult
ActOnDefaultStmt(SourceLocation DefaultLoc,SourceLocation ColonLoc,Stmt * SubStmt,Scope * CurScope)446 Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
447                        Stmt *SubStmt, Scope *CurScope) {
448   DiagnoseUnusedExprResult(SubStmt);
449 
450   if (getCurFunction()->SwitchStack.empty()) {
451     Diag(DefaultLoc, diag::err_default_not_in_switch);
452     return SubStmt;
453   }
454 
455   DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
456   getCurFunction()->SwitchStack.back()->addSwitchCase(DS);
457   return DS;
458 }
459 
460 StmtResult
ActOnLabelStmt(SourceLocation IdentLoc,LabelDecl * TheDecl,SourceLocation ColonLoc,Stmt * SubStmt)461 Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
462                      SourceLocation ColonLoc, Stmt *SubStmt) {
463   // If the label was multiply defined, reject it now.
464   if (TheDecl->getStmt()) {
465     Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName();
466     Diag(TheDecl->getLocation(), diag::note_previous_definition);
467     return SubStmt;
468   }
469 
470   // Otherwise, things are good.  Fill in the declaration and return it.
471   LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt);
472   TheDecl->setStmt(LS);
473   if (!TheDecl->isGnuLocal()) {
474     TheDecl->setLocStart(IdentLoc);
475     if (!TheDecl->isMSAsmLabel()) {
476       // Don't update the location of MS ASM labels.  These will result in
477       // a diagnostic, and changing the location here will mess that up.
478       TheDecl->setLocation(IdentLoc);
479     }
480   }
481   return LS;
482 }
483 
ActOnAttributedStmt(SourceLocation AttrLoc,ArrayRef<const Attr * > Attrs,Stmt * SubStmt)484 StmtResult Sema::ActOnAttributedStmt(SourceLocation AttrLoc,
485                                      ArrayRef<const Attr*> Attrs,
486                                      Stmt *SubStmt) {
487   // Fill in the declaration and return it.
488   AttributedStmt *LS = AttributedStmt::Create(Context, AttrLoc, Attrs, SubStmt);
489   return LS;
490 }
491 
492 namespace {
493 class CommaVisitor : public EvaluatedExprVisitor<CommaVisitor> {
494   typedef EvaluatedExprVisitor<CommaVisitor> Inherited;
495   Sema &SemaRef;
496 public:
CommaVisitor(Sema & SemaRef)497   CommaVisitor(Sema &SemaRef) : Inherited(SemaRef.Context), SemaRef(SemaRef) {}
VisitBinaryOperator(BinaryOperator * E)498   void VisitBinaryOperator(BinaryOperator *E) {
499     if (E->getOpcode() == BO_Comma)
500       SemaRef.DiagnoseCommaOperator(E->getLHS(), E->getExprLoc());
501     EvaluatedExprVisitor<CommaVisitor>::VisitBinaryOperator(E);
502   }
503 };
504 }
505 
506 StmtResult
ActOnIfStmt(SourceLocation IfLoc,bool IsConstexpr,Stmt * InitStmt,ConditionResult Cond,Stmt * thenStmt,SourceLocation ElseLoc,Stmt * elseStmt)507 Sema::ActOnIfStmt(SourceLocation IfLoc, bool IsConstexpr, Stmt *InitStmt,
508                   ConditionResult Cond,
509                   Stmt *thenStmt, SourceLocation ElseLoc,
510                   Stmt *elseStmt) {
511   if (Cond.isInvalid())
512     Cond = ConditionResult(
513         *this, nullptr,
514         MakeFullExpr(new (Context) OpaqueValueExpr(SourceLocation(),
515                                                    Context.BoolTy, VK_RValue),
516                      IfLoc),
517         false);
518 
519   Expr *CondExpr = Cond.get().second;
520   if (!Diags.isIgnored(diag::warn_comma_operator,
521                        CondExpr->getExprLoc()))
522     CommaVisitor(*this).Visit(CondExpr);
523 
524   if (!elseStmt)
525     DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), thenStmt,
526                           diag::warn_empty_if_body);
527 
528   return BuildIfStmt(IfLoc, IsConstexpr, InitStmt, Cond, thenStmt, ElseLoc,
529                      elseStmt);
530 }
531 
BuildIfStmt(SourceLocation IfLoc,bool IsConstexpr,Stmt * InitStmt,ConditionResult Cond,Stmt * thenStmt,SourceLocation ElseLoc,Stmt * elseStmt)532 StmtResult Sema::BuildIfStmt(SourceLocation IfLoc, bool IsConstexpr,
533                              Stmt *InitStmt, ConditionResult Cond,
534                              Stmt *thenStmt, SourceLocation ElseLoc,
535                              Stmt *elseStmt) {
536   if (Cond.isInvalid())
537     return StmtError();
538 
539   if (IsConstexpr)
540     getCurFunction()->setHasBranchProtectedScope();
541 
542   DiagnoseUnusedExprResult(thenStmt);
543   DiagnoseUnusedExprResult(elseStmt);
544 
545   return new (Context)
546       IfStmt(Context, IfLoc, IsConstexpr, InitStmt, Cond.get().first,
547              Cond.get().second, thenStmt, ElseLoc, elseStmt);
548 }
549 
550 namespace {
551   struct CaseCompareFunctor {
operator ()__anon27b5dcff0311::CaseCompareFunctor552     bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
553                     const llvm::APSInt &RHS) {
554       return LHS.first < RHS;
555     }
operator ()__anon27b5dcff0311::CaseCompareFunctor556     bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
557                     const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
558       return LHS.first < RHS.first;
559     }
operator ()__anon27b5dcff0311::CaseCompareFunctor560     bool operator()(const llvm::APSInt &LHS,
561                     const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
562       return LHS < RHS.first;
563     }
564   };
565 }
566 
567 /// CmpCaseVals - Comparison predicate for sorting case values.
568 ///
CmpCaseVals(const std::pair<llvm::APSInt,CaseStmt * > & lhs,const std::pair<llvm::APSInt,CaseStmt * > & rhs)569 static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
570                         const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
571   if (lhs.first < rhs.first)
572     return true;
573 
574   if (lhs.first == rhs.first &&
575       lhs.second->getCaseLoc().getRawEncoding()
576        < rhs.second->getCaseLoc().getRawEncoding())
577     return true;
578   return false;
579 }
580 
581 /// CmpEnumVals - Comparison predicate for sorting enumeration values.
582 ///
CmpEnumVals(const std::pair<llvm::APSInt,EnumConstantDecl * > & lhs,const std::pair<llvm::APSInt,EnumConstantDecl * > & rhs)583 static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
584                         const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
585 {
586   return lhs.first < rhs.first;
587 }
588 
589 /// EqEnumVals - Comparison preficate for uniqing enumeration values.
590 ///
EqEnumVals(const std::pair<llvm::APSInt,EnumConstantDecl * > & lhs,const std::pair<llvm::APSInt,EnumConstantDecl * > & rhs)591 static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
592                        const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
593 {
594   return lhs.first == rhs.first;
595 }
596 
597 /// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
598 /// potentially integral-promoted expression @p expr.
GetTypeBeforeIntegralPromotion(Expr * & expr)599 static QualType GetTypeBeforeIntegralPromotion(Expr *&expr) {
600   if (ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(expr))
601     expr = cleanups->getSubExpr();
602   while (ImplicitCastExpr *impcast = dyn_cast<ImplicitCastExpr>(expr)) {
603     if (impcast->getCastKind() != CK_IntegralCast) break;
604     expr = impcast->getSubExpr();
605   }
606   return expr->getType();
607 }
608 
CheckSwitchCondition(SourceLocation SwitchLoc,Expr * Cond)609 ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) {
610   class SwitchConvertDiagnoser : public ICEConvertDiagnoser {
611     Expr *Cond;
612 
613   public:
614     SwitchConvertDiagnoser(Expr *Cond)
615         : ICEConvertDiagnoser(/*AllowScopedEnumerations*/true, false, true),
616           Cond(Cond) {}
617 
618     SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
619                                          QualType T) override {
620       return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T;
621     }
622 
623     SemaDiagnosticBuilder diagnoseIncomplete(
624         Sema &S, SourceLocation Loc, QualType T) override {
625       return S.Diag(Loc, diag::err_switch_incomplete_class_type)
626                << T << Cond->getSourceRange();
627     }
628 
629     SemaDiagnosticBuilder diagnoseExplicitConv(
630         Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
631       return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy;
632     }
633 
634     SemaDiagnosticBuilder noteExplicitConv(
635         Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
636       return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
637         << ConvTy->isEnumeralType() << ConvTy;
638     }
639 
640     SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
641                                             QualType T) override {
642       return S.Diag(Loc, diag::err_switch_multiple_conversions) << T;
643     }
644 
645     SemaDiagnosticBuilder noteAmbiguous(
646         Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
647       return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
648       << ConvTy->isEnumeralType() << ConvTy;
649     }
650 
651     SemaDiagnosticBuilder diagnoseConversion(
652         Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
653       llvm_unreachable("conversion functions are permitted");
654     }
655   } SwitchDiagnoser(Cond);
656 
657   ExprResult CondResult =
658       PerformContextualImplicitConversion(SwitchLoc, Cond, SwitchDiagnoser);
659   if (CondResult.isInvalid())
660     return ExprError();
661 
662   // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
663   return UsualUnaryConversions(CondResult.get());
664 }
665 
ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,Stmt * InitStmt,ConditionResult Cond)666 StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
667                                         Stmt *InitStmt, ConditionResult Cond) {
668   if (Cond.isInvalid())
669     return StmtError();
670 
671   getCurFunction()->setHasBranchIntoScope();
672 
673   SwitchStmt *SS = new (Context)
674       SwitchStmt(Context, InitStmt, Cond.get().first, Cond.get().second);
675   getCurFunction()->SwitchStack.push_back(SS);
676   return SS;
677 }
678 
AdjustAPSInt(llvm::APSInt & Val,unsigned BitWidth,bool IsSigned)679 static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
680   Val = Val.extOrTrunc(BitWidth);
681   Val.setIsSigned(IsSigned);
682 }
683 
684 /// Check the specified case value is in range for the given unpromoted switch
685 /// type.
checkCaseValue(Sema & S,SourceLocation Loc,const llvm::APSInt & Val,unsigned UnpromotedWidth,bool UnpromotedSign)686 static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val,
687                            unsigned UnpromotedWidth, bool UnpromotedSign) {
688   // If the case value was signed and negative and the switch expression is
689   // unsigned, don't bother to warn: this is implementation-defined behavior.
690   // FIXME: Introduce a second, default-ignored warning for this case?
691   if (UnpromotedWidth < Val.getBitWidth()) {
692     llvm::APSInt ConvVal(Val);
693     AdjustAPSInt(ConvVal, UnpromotedWidth, UnpromotedSign);
694     AdjustAPSInt(ConvVal, Val.getBitWidth(), Val.isSigned());
695     // FIXME: Use different diagnostics for overflow  in conversion to promoted
696     // type versus "switch expression cannot have this value". Use proper
697     // IntRange checking rather than just looking at the unpromoted type here.
698     if (ConvVal != Val)
699       S.Diag(Loc, diag::warn_case_value_overflow) << Val.toString(10)
700                                                   << ConvVal.toString(10);
701   }
702 }
703 
704 typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
705 
706 /// Returns true if we should emit a diagnostic about this case expression not
707 /// being a part of the enum used in the switch controlling expression.
ShouldDiagnoseSwitchCaseNotInEnum(const Sema & S,const EnumDecl * ED,const Expr * CaseExpr,EnumValsTy::iterator & EI,EnumValsTy::iterator & EIEnd,const llvm::APSInt & Val)708 static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
709                                               const EnumDecl *ED,
710                                               const Expr *CaseExpr,
711                                               EnumValsTy::iterator &EI,
712                                               EnumValsTy::iterator &EIEnd,
713                                               const llvm::APSInt &Val) {
714   if (const DeclRefExpr *DRE =
715           dyn_cast<DeclRefExpr>(CaseExpr->IgnoreParenImpCasts())) {
716     if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
717       QualType VarType = VD->getType();
718       QualType EnumType = S.Context.getTypeDeclType(ED);
719       if (VD->hasGlobalStorage() && VarType.isConstQualified() &&
720           S.Context.hasSameUnqualifiedType(EnumType, VarType))
721         return false;
722     }
723   }
724 
725   if (ED->hasAttr<FlagEnumAttr>()) {
726     return !S.IsValueInFlagEnum(ED, Val, false);
727   } else {
728     while (EI != EIEnd && EI->first < Val)
729       EI++;
730 
731     if (EI != EIEnd && EI->first == Val)
732       return false;
733   }
734 
735   return true;
736 }
737 
738 StmtResult
ActOnFinishSwitchStmt(SourceLocation SwitchLoc,Stmt * Switch,Stmt * BodyStmt)739 Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
740                             Stmt *BodyStmt) {
741   SwitchStmt *SS = cast<SwitchStmt>(Switch);
742   assert(SS == getCurFunction()->SwitchStack.back() &&
743          "switch stack missing push/pop!");
744 
745   getCurFunction()->SwitchStack.pop_back();
746 
747   if (!BodyStmt) return StmtError();
748   SS->setBody(BodyStmt, SwitchLoc);
749 
750   Expr *CondExpr = SS->getCond();
751   if (!CondExpr) return StmtError();
752 
753   QualType CondType = CondExpr->getType();
754 
755   Expr *CondExprBeforePromotion = CondExpr;
756   QualType CondTypeBeforePromotion =
757       GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
758 
759   // C++ 6.4.2.p2:
760   // Integral promotions are performed (on the switch condition).
761   //
762   // A case value unrepresentable by the original switch condition
763   // type (before the promotion) doesn't make sense, even when it can
764   // be represented by the promoted type.  Therefore we need to find
765   // the pre-promotion type of the switch condition.
766   if (!CondExpr->isTypeDependent()) {
767     // We have already converted the expression to an integral or enumeration
768     // type, when we started the switch statement. If we don't have an
769     // appropriate type now, just return an error.
770     if (!CondType->isIntegralOrEnumerationType())
771       return StmtError();
772 
773     if (CondExpr->isKnownToHaveBooleanValue()) {
774       // switch(bool_expr) {...} is often a programmer error, e.g.
775       //   switch(n && mask) { ... }  // Doh - should be "n & mask".
776       // One can always use an if statement instead of switch(bool_expr).
777       Diag(SwitchLoc, diag::warn_bool_switch_condition)
778           << CondExpr->getSourceRange();
779     }
780   }
781 
782   // Get the bitwidth of the switched-on value after promotions. We must
783   // convert the integer case values to this width before comparison.
784   bool HasDependentValue
785     = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
786   unsigned CondWidth = HasDependentValue ? 0 : Context.getIntWidth(CondType);
787   bool CondIsSigned = CondType->isSignedIntegerOrEnumerationType();
788 
789   // Get the width and signedness that the condition might actually have, for
790   // warning purposes.
791   // FIXME: Grab an IntRange for the condition rather than using the unpromoted
792   // type.
793   unsigned CondWidthBeforePromotion
794     = HasDependentValue ? 0 : Context.getIntWidth(CondTypeBeforePromotion);
795   bool CondIsSignedBeforePromotion
796     = CondTypeBeforePromotion->isSignedIntegerOrEnumerationType();
797 
798   // Accumulate all of the case values in a vector so that we can sort them
799   // and detect duplicates.  This vector contains the APInt for the case after
800   // it has been converted to the condition type.
801   typedef SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
802   CaseValsTy CaseVals;
803 
804   // Keep track of any GNU case ranges we see.  The APSInt is the low value.
805   typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
806   CaseRangesTy CaseRanges;
807 
808   DefaultStmt *TheDefaultStmt = nullptr;
809 
810   bool CaseListIsErroneous = false;
811 
812   for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
813        SC = SC->getNextSwitchCase()) {
814 
815     if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
816       if (TheDefaultStmt) {
817         Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
818         Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
819 
820         // FIXME: Remove the default statement from the switch block so that
821         // we'll return a valid AST.  This requires recursing down the AST and
822         // finding it, not something we are set up to do right now.  For now,
823         // just lop the entire switch stmt out of the AST.
824         CaseListIsErroneous = true;
825       }
826       TheDefaultStmt = DS;
827 
828     } else {
829       CaseStmt *CS = cast<CaseStmt>(SC);
830 
831       Expr *Lo = CS->getLHS();
832 
833       if (Lo->isTypeDependent() || Lo->isValueDependent()) {
834         HasDependentValue = true;
835         break;
836       }
837 
838       llvm::APSInt LoVal;
839 
840       if (getLangOpts().CPlusPlus11) {
841         // C++11 [stmt.switch]p2: the constant-expression shall be a converted
842         // constant expression of the promoted type of the switch condition.
843         ExprResult ConvLo =
844           CheckConvertedConstantExpression(Lo, CondType, LoVal, CCEK_CaseValue);
845         if (ConvLo.isInvalid()) {
846           CaseListIsErroneous = true;
847           continue;
848         }
849         Lo = ConvLo.get();
850       } else {
851         // We already verified that the expression has a i-c-e value (C99
852         // 6.8.4.2p3) - get that value now.
853         LoVal = Lo->EvaluateKnownConstInt(Context);
854 
855         // If the LHS is not the same type as the condition, insert an implicit
856         // cast.
857         Lo = DefaultLvalueConversion(Lo).get();
858         Lo = ImpCastExprToType(Lo, CondType, CK_IntegralCast).get();
859       }
860 
861       // Check the unconverted value is within the range of possible values of
862       // the switch expression.
863       checkCaseValue(*this, Lo->getLocStart(), LoVal,
864                      CondWidthBeforePromotion, CondIsSignedBeforePromotion);
865 
866       // Convert the value to the same width/sign as the condition.
867       AdjustAPSInt(LoVal, CondWidth, CondIsSigned);
868 
869       CS->setLHS(Lo);
870 
871       // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
872       if (CS->getRHS()) {
873         if (CS->getRHS()->isTypeDependent() ||
874             CS->getRHS()->isValueDependent()) {
875           HasDependentValue = true;
876           break;
877         }
878         CaseRanges.push_back(std::make_pair(LoVal, CS));
879       } else
880         CaseVals.push_back(std::make_pair(LoVal, CS));
881     }
882   }
883 
884   if (!HasDependentValue) {
885     // If we don't have a default statement, check whether the
886     // condition is constant.
887     llvm::APSInt ConstantCondValue;
888     bool HasConstantCond = false;
889     if (!HasDependentValue && !TheDefaultStmt) {
890       HasConstantCond = CondExpr->EvaluateAsInt(ConstantCondValue, Context,
891                                                 Expr::SE_AllowSideEffects);
892       assert(!HasConstantCond ||
893              (ConstantCondValue.getBitWidth() == CondWidth &&
894               ConstantCondValue.isSigned() == CondIsSigned));
895     }
896     bool ShouldCheckConstantCond = HasConstantCond;
897 
898     // Sort all the scalar case values so we can easily detect duplicates.
899     std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
900 
901     if (!CaseVals.empty()) {
902       for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
903         if (ShouldCheckConstantCond &&
904             CaseVals[i].first == ConstantCondValue)
905           ShouldCheckConstantCond = false;
906 
907         if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
908           // If we have a duplicate, report it.
909           // First, determine if either case value has a name
910           StringRef PrevString, CurrString;
911           Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts();
912           Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts();
913           if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(PrevCase)) {
914             PrevString = DeclRef->getDecl()->getName();
915           }
916           if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(CurrCase)) {
917             CurrString = DeclRef->getDecl()->getName();
918           }
919           SmallString<16> CaseValStr;
920           CaseVals[i-1].first.toString(CaseValStr);
921 
922           if (PrevString == CurrString)
923             Diag(CaseVals[i].second->getLHS()->getLocStart(),
924                  diag::err_duplicate_case) <<
925                  (PrevString.empty() ? StringRef(CaseValStr) : PrevString);
926           else
927             Diag(CaseVals[i].second->getLHS()->getLocStart(),
928                  diag::err_duplicate_case_differing_expr) <<
929                  (PrevString.empty() ? StringRef(CaseValStr) : PrevString) <<
930                  (CurrString.empty() ? StringRef(CaseValStr) : CurrString) <<
931                  CaseValStr;
932 
933           Diag(CaseVals[i-1].second->getLHS()->getLocStart(),
934                diag::note_duplicate_case_prev);
935           // FIXME: We really want to remove the bogus case stmt from the
936           // substmt, but we have no way to do this right now.
937           CaseListIsErroneous = true;
938         }
939       }
940     }
941 
942     // Detect duplicate case ranges, which usually don't exist at all in
943     // the first place.
944     if (!CaseRanges.empty()) {
945       // Sort all the case ranges by their low value so we can easily detect
946       // overlaps between ranges.
947       std::stable_sort(CaseRanges.begin(), CaseRanges.end());
948 
949       // Scan the ranges, computing the high values and removing empty ranges.
950       std::vector<llvm::APSInt> HiVals;
951       for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
952         llvm::APSInt &LoVal = CaseRanges[i].first;
953         CaseStmt *CR = CaseRanges[i].second;
954         Expr *Hi = CR->getRHS();
955         llvm::APSInt HiVal;
956 
957         if (getLangOpts().CPlusPlus11) {
958           // C++11 [stmt.switch]p2: the constant-expression shall be a converted
959           // constant expression of the promoted type of the switch condition.
960           ExprResult ConvHi =
961             CheckConvertedConstantExpression(Hi, CondType, HiVal,
962                                              CCEK_CaseValue);
963           if (ConvHi.isInvalid()) {
964             CaseListIsErroneous = true;
965             continue;
966           }
967           Hi = ConvHi.get();
968         } else {
969           HiVal = Hi->EvaluateKnownConstInt(Context);
970 
971           // If the RHS is not the same type as the condition, insert an
972           // implicit cast.
973           Hi = DefaultLvalueConversion(Hi).get();
974           Hi = ImpCastExprToType(Hi, CondType, CK_IntegralCast).get();
975         }
976 
977         // Check the unconverted value is within the range of possible values of
978         // the switch expression.
979         checkCaseValue(*this, Hi->getLocStart(), HiVal,
980                        CondWidthBeforePromotion, CondIsSignedBeforePromotion);
981 
982         // Convert the value to the same width/sign as the condition.
983         AdjustAPSInt(HiVal, CondWidth, CondIsSigned);
984 
985         CR->setRHS(Hi);
986 
987         // If the low value is bigger than the high value, the case is empty.
988         if (LoVal > HiVal) {
989           Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
990             << SourceRange(CR->getLHS()->getLocStart(),
991                            Hi->getLocEnd());
992           CaseRanges.erase(CaseRanges.begin()+i);
993           --i;
994           --e;
995           continue;
996         }
997 
998         if (ShouldCheckConstantCond &&
999             LoVal <= ConstantCondValue &&
1000             ConstantCondValue <= HiVal)
1001           ShouldCheckConstantCond = false;
1002 
1003         HiVals.push_back(HiVal);
1004       }
1005 
1006       // Rescan the ranges, looking for overlap with singleton values and other
1007       // ranges.  Since the range list is sorted, we only need to compare case
1008       // ranges with their neighbors.
1009       for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1010         llvm::APSInt &CRLo = CaseRanges[i].first;
1011         llvm::APSInt &CRHi = HiVals[i];
1012         CaseStmt *CR = CaseRanges[i].second;
1013 
1014         // Check to see whether the case range overlaps with any
1015         // singleton cases.
1016         CaseStmt *OverlapStmt = nullptr;
1017         llvm::APSInt OverlapVal(32);
1018 
1019         // Find the smallest value >= the lower bound.  If I is in the
1020         // case range, then we have overlap.
1021         CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
1022                                                   CaseVals.end(), CRLo,
1023                                                   CaseCompareFunctor());
1024         if (I != CaseVals.end() && I->first < CRHi) {
1025           OverlapVal  = I->first;   // Found overlap with scalar.
1026           OverlapStmt = I->second;
1027         }
1028 
1029         // Find the smallest value bigger than the upper bound.
1030         I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
1031         if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
1032           OverlapVal  = (I-1)->first;      // Found overlap with scalar.
1033           OverlapStmt = (I-1)->second;
1034         }
1035 
1036         // Check to see if this case stmt overlaps with the subsequent
1037         // case range.
1038         if (i && CRLo <= HiVals[i-1]) {
1039           OverlapVal  = HiVals[i-1];       // Found overlap with range.
1040           OverlapStmt = CaseRanges[i-1].second;
1041         }
1042 
1043         if (OverlapStmt) {
1044           // If we have a duplicate, report it.
1045           Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
1046             << OverlapVal.toString(10);
1047           Diag(OverlapStmt->getLHS()->getLocStart(),
1048                diag::note_duplicate_case_prev);
1049           // FIXME: We really want to remove the bogus case stmt from the
1050           // substmt, but we have no way to do this right now.
1051           CaseListIsErroneous = true;
1052         }
1053       }
1054     }
1055 
1056     // Complain if we have a constant condition and we didn't find a match.
1057     if (!CaseListIsErroneous && ShouldCheckConstantCond) {
1058       // TODO: it would be nice if we printed enums as enums, chars as
1059       // chars, etc.
1060       Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
1061         << ConstantCondValue.toString(10)
1062         << CondExpr->getSourceRange();
1063     }
1064 
1065     // Check to see if switch is over an Enum and handles all of its
1066     // values.  We only issue a warning if there is not 'default:', but
1067     // we still do the analysis to preserve this information in the AST
1068     // (which can be used by flow-based analyes).
1069     //
1070     const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
1071 
1072     // If switch has default case, then ignore it.
1073     if (!CaseListIsErroneous  && !HasConstantCond && ET) {
1074       const EnumDecl *ED = ET->getDecl();
1075       EnumValsTy EnumVals;
1076 
1077       // Gather all enum values, set their type and sort them,
1078       // allowing easier comparison with CaseVals.
1079       for (auto *EDI : ED->enumerators()) {
1080         llvm::APSInt Val = EDI->getInitVal();
1081         AdjustAPSInt(Val, CondWidth, CondIsSigned);
1082         EnumVals.push_back(std::make_pair(Val, EDI));
1083       }
1084       std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
1085       auto EI = EnumVals.begin(), EIEnd =
1086         std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1087 
1088       // See which case values aren't in enum.
1089       for (CaseValsTy::const_iterator CI = CaseVals.begin();
1090           CI != CaseVals.end(); CI++) {
1091         Expr *CaseExpr = CI->second->getLHS();
1092         if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1093                                               CI->first))
1094           Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1095             << CondTypeBeforePromotion;
1096       }
1097 
1098       // See which of case ranges aren't in enum
1099       EI = EnumVals.begin();
1100       for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
1101           RI != CaseRanges.end(); RI++) {
1102         Expr *CaseExpr = RI->second->getLHS();
1103         if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1104                                               RI->first))
1105           Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1106             << CondTypeBeforePromotion;
1107 
1108         llvm::APSInt Hi =
1109           RI->second->getRHS()->EvaluateKnownConstInt(Context);
1110         AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1111 
1112         CaseExpr = RI->second->getRHS();
1113         if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1114                                               Hi))
1115           Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1116             << CondTypeBeforePromotion;
1117       }
1118 
1119       // Check which enum vals aren't in switch
1120       auto CI = CaseVals.begin();
1121       auto RI = CaseRanges.begin();
1122       bool hasCasesNotInSwitch = false;
1123 
1124       SmallVector<DeclarationName,8> UnhandledNames;
1125 
1126       for (EI = EnumVals.begin(); EI != EIEnd; EI++){
1127         // Drop unneeded case values
1128         while (CI != CaseVals.end() && CI->first < EI->first)
1129           CI++;
1130 
1131         if (CI != CaseVals.end() && CI->first == EI->first)
1132           continue;
1133 
1134         // Drop unneeded case ranges
1135         for (; RI != CaseRanges.end(); RI++) {
1136           llvm::APSInt Hi =
1137             RI->second->getRHS()->EvaluateKnownConstInt(Context);
1138           AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1139           if (EI->first <= Hi)
1140             break;
1141         }
1142 
1143         if (RI == CaseRanges.end() || EI->first < RI->first) {
1144           hasCasesNotInSwitch = true;
1145           UnhandledNames.push_back(EI->second->getDeclName());
1146         }
1147       }
1148 
1149       if (TheDefaultStmt && UnhandledNames.empty())
1150         Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
1151 
1152       // Produce a nice diagnostic if multiple values aren't handled.
1153       if (!UnhandledNames.empty()) {
1154         DiagnosticBuilder DB = Diag(CondExpr->getExprLoc(),
1155                                     TheDefaultStmt ? diag::warn_def_missing_case
1156                                                    : diag::warn_missing_case)
1157                                << (int)UnhandledNames.size();
1158 
1159         for (size_t I = 0, E = std::min(UnhandledNames.size(), (size_t)3);
1160              I != E; ++I)
1161           DB << UnhandledNames[I];
1162       }
1163 
1164       if (!hasCasesNotInSwitch)
1165         SS->setAllEnumCasesCovered();
1166     }
1167   }
1168 
1169   if (BodyStmt)
1170     DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), BodyStmt,
1171                           diag::warn_empty_switch_body);
1172 
1173   // FIXME: If the case list was broken is some way, we don't have a good system
1174   // to patch it up.  Instead, just return the whole substmt as broken.
1175   if (CaseListIsErroneous)
1176     return StmtError();
1177 
1178   return SS;
1179 }
1180 
1181 void
DiagnoseAssignmentEnum(QualType DstType,QualType SrcType,Expr * SrcExpr)1182 Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
1183                              Expr *SrcExpr) {
1184   if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc()))
1185     return;
1186 
1187   if (const EnumType *ET = DstType->getAs<EnumType>())
1188     if (!Context.hasSameUnqualifiedType(SrcType, DstType) &&
1189         SrcType->isIntegerType()) {
1190       if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
1191           SrcExpr->isIntegerConstantExpr(Context)) {
1192         // Get the bitwidth of the enum value before promotions.
1193         unsigned DstWidth = Context.getIntWidth(DstType);
1194         bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
1195 
1196         llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
1197         AdjustAPSInt(RhsVal, DstWidth, DstIsSigned);
1198         const EnumDecl *ED = ET->getDecl();
1199 
1200         if (ED->hasAttr<FlagEnumAttr>()) {
1201           if (!IsValueInFlagEnum(ED, RhsVal, true))
1202             Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1203               << DstType.getUnqualifiedType();
1204         } else {
1205           typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl *>, 64>
1206               EnumValsTy;
1207           EnumValsTy EnumVals;
1208 
1209           // Gather all enum values, set their type and sort them,
1210           // allowing easier comparison with rhs constant.
1211           for (auto *EDI : ED->enumerators()) {
1212             llvm::APSInt Val = EDI->getInitVal();
1213             AdjustAPSInt(Val, DstWidth, DstIsSigned);
1214             EnumVals.push_back(std::make_pair(Val, EDI));
1215           }
1216           if (EnumVals.empty())
1217             return;
1218           std::stable_sort(EnumVals.begin(), EnumVals.end(), CmpEnumVals);
1219           EnumValsTy::iterator EIend =
1220               std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1221 
1222           // See which values aren't in the enum.
1223           EnumValsTy::const_iterator EI = EnumVals.begin();
1224           while (EI != EIend && EI->first < RhsVal)
1225             EI++;
1226           if (EI == EIend || EI->first != RhsVal) {
1227             Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1228                 << DstType.getUnqualifiedType();
1229           }
1230         }
1231       }
1232     }
1233 }
1234 
ActOnWhileStmt(SourceLocation WhileLoc,ConditionResult Cond,Stmt * Body)1235 StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc, ConditionResult Cond,
1236                                 Stmt *Body) {
1237   if (Cond.isInvalid())
1238     return StmtError();
1239 
1240   auto CondVal = Cond.get();
1241   CheckBreakContinueBinding(CondVal.second);
1242 
1243   if (CondVal.second &&
1244       !Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc()))
1245     CommaVisitor(*this).Visit(CondVal.second);
1246 
1247   DiagnoseUnusedExprResult(Body);
1248 
1249   if (isa<NullStmt>(Body))
1250     getCurCompoundScope().setHasEmptyLoopBodies();
1251 
1252   return new (Context)
1253       WhileStmt(Context, CondVal.first, CondVal.second, Body, WhileLoc);
1254 }
1255 
1256 StmtResult
ActOnDoStmt(SourceLocation DoLoc,Stmt * Body,SourceLocation WhileLoc,SourceLocation CondLParen,Expr * Cond,SourceLocation CondRParen)1257 Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
1258                   SourceLocation WhileLoc, SourceLocation CondLParen,
1259                   Expr *Cond, SourceLocation CondRParen) {
1260   assert(Cond && "ActOnDoStmt(): missing expression");
1261 
1262   CheckBreakContinueBinding(Cond);
1263   ExprResult CondResult = CheckBooleanCondition(DoLoc, Cond);
1264   if (CondResult.isInvalid())
1265     return StmtError();
1266   Cond = CondResult.get();
1267 
1268   CondResult = ActOnFinishFullExpr(Cond, DoLoc);
1269   if (CondResult.isInvalid())
1270     return StmtError();
1271   Cond = CondResult.get();
1272 
1273   DiagnoseUnusedExprResult(Body);
1274 
1275   return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen);
1276 }
1277 
1278 namespace {
1279   // This visitor will traverse a conditional statement and store all
1280   // the evaluated decls into a vector.  Simple is set to true if none
1281   // of the excluded constructs are used.
1282   class DeclExtractor : public EvaluatedExprVisitor<DeclExtractor> {
1283     llvm::SmallPtrSetImpl<VarDecl*> &Decls;
1284     SmallVectorImpl<SourceRange> &Ranges;
1285     bool Simple;
1286   public:
1287     typedef EvaluatedExprVisitor<DeclExtractor> Inherited;
1288 
DeclExtractor(Sema & S,llvm::SmallPtrSetImpl<VarDecl * > & Decls,SmallVectorImpl<SourceRange> & Ranges)1289     DeclExtractor(Sema &S, llvm::SmallPtrSetImpl<VarDecl*> &Decls,
1290                   SmallVectorImpl<SourceRange> &Ranges) :
1291         Inherited(S.Context),
1292         Decls(Decls),
1293         Ranges(Ranges),
1294         Simple(true) {}
1295 
isSimple()1296     bool isSimple() { return Simple; }
1297 
1298     // Replaces the method in EvaluatedExprVisitor.
VisitMemberExpr(MemberExpr * E)1299     void VisitMemberExpr(MemberExpr* E) {
1300       Simple = false;
1301     }
1302 
1303     // Any Stmt not whitelisted will cause the condition to be marked complex.
VisitStmt(Stmt * S)1304     void VisitStmt(Stmt *S) {
1305       Simple = false;
1306     }
1307 
VisitBinaryOperator(BinaryOperator * E)1308     void VisitBinaryOperator(BinaryOperator *E) {
1309       Visit(E->getLHS());
1310       Visit(E->getRHS());
1311     }
1312 
VisitCastExpr(CastExpr * E)1313     void VisitCastExpr(CastExpr *E) {
1314       Visit(E->getSubExpr());
1315     }
1316 
VisitUnaryOperator(UnaryOperator * E)1317     void VisitUnaryOperator(UnaryOperator *E) {
1318       // Skip checking conditionals with derefernces.
1319       if (E->getOpcode() == UO_Deref)
1320         Simple = false;
1321       else
1322         Visit(E->getSubExpr());
1323     }
1324 
VisitConditionalOperator(ConditionalOperator * E)1325     void VisitConditionalOperator(ConditionalOperator *E) {
1326       Visit(E->getCond());
1327       Visit(E->getTrueExpr());
1328       Visit(E->getFalseExpr());
1329     }
1330 
VisitParenExpr(ParenExpr * E)1331     void VisitParenExpr(ParenExpr *E) {
1332       Visit(E->getSubExpr());
1333     }
1334 
VisitBinaryConditionalOperator(BinaryConditionalOperator * E)1335     void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
1336       Visit(E->getOpaqueValue()->getSourceExpr());
1337       Visit(E->getFalseExpr());
1338     }
1339 
VisitIntegerLiteral(IntegerLiteral * E)1340     void VisitIntegerLiteral(IntegerLiteral *E) { }
VisitFloatingLiteral(FloatingLiteral * E)1341     void VisitFloatingLiteral(FloatingLiteral *E) { }
VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr * E)1342     void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { }
VisitCharacterLiteral(CharacterLiteral * E)1343     void VisitCharacterLiteral(CharacterLiteral *E) { }
VisitGNUNullExpr(GNUNullExpr * E)1344     void VisitGNUNullExpr(GNUNullExpr *E) { }
VisitImaginaryLiteral(ImaginaryLiteral * E)1345     void VisitImaginaryLiteral(ImaginaryLiteral *E) { }
1346 
VisitDeclRefExpr(DeclRefExpr * E)1347     void VisitDeclRefExpr(DeclRefExpr *E) {
1348       VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
1349       if (!VD) return;
1350 
1351       Ranges.push_back(E->getSourceRange());
1352 
1353       Decls.insert(VD);
1354     }
1355 
1356   }; // end class DeclExtractor
1357 
1358   // DeclMatcher checks to see if the decls are used in a non-evaluated
1359   // context.
1360   class DeclMatcher : public EvaluatedExprVisitor<DeclMatcher> {
1361     llvm::SmallPtrSetImpl<VarDecl*> &Decls;
1362     bool FoundDecl;
1363 
1364   public:
1365     typedef EvaluatedExprVisitor<DeclMatcher> Inherited;
1366 
DeclMatcher(Sema & S,llvm::SmallPtrSetImpl<VarDecl * > & Decls,Stmt * Statement)1367     DeclMatcher(Sema &S, llvm::SmallPtrSetImpl<VarDecl*> &Decls,
1368                 Stmt *Statement) :
1369         Inherited(S.Context), Decls(Decls), FoundDecl(false) {
1370       if (!Statement) return;
1371 
1372       Visit(Statement);
1373     }
1374 
VisitReturnStmt(ReturnStmt * S)1375     void VisitReturnStmt(ReturnStmt *S) {
1376       FoundDecl = true;
1377     }
1378 
VisitBreakStmt(BreakStmt * S)1379     void VisitBreakStmt(BreakStmt *S) {
1380       FoundDecl = true;
1381     }
1382 
VisitGotoStmt(GotoStmt * S)1383     void VisitGotoStmt(GotoStmt *S) {
1384       FoundDecl = true;
1385     }
1386 
VisitCastExpr(CastExpr * E)1387     void VisitCastExpr(CastExpr *E) {
1388       if (E->getCastKind() == CK_LValueToRValue)
1389         CheckLValueToRValueCast(E->getSubExpr());
1390       else
1391         Visit(E->getSubExpr());
1392     }
1393 
CheckLValueToRValueCast(Expr * E)1394     void CheckLValueToRValueCast(Expr *E) {
1395       E = E->IgnoreParenImpCasts();
1396 
1397       if (isa<DeclRefExpr>(E)) {
1398         return;
1399       }
1400 
1401       if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
1402         Visit(CO->getCond());
1403         CheckLValueToRValueCast(CO->getTrueExpr());
1404         CheckLValueToRValueCast(CO->getFalseExpr());
1405         return;
1406       }
1407 
1408       if (BinaryConditionalOperator *BCO =
1409               dyn_cast<BinaryConditionalOperator>(E)) {
1410         CheckLValueToRValueCast(BCO->getOpaqueValue()->getSourceExpr());
1411         CheckLValueToRValueCast(BCO->getFalseExpr());
1412         return;
1413       }
1414 
1415       Visit(E);
1416     }
1417 
VisitDeclRefExpr(DeclRefExpr * E)1418     void VisitDeclRefExpr(DeclRefExpr *E) {
1419       if (VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
1420         if (Decls.count(VD))
1421           FoundDecl = true;
1422     }
1423 
VisitPseudoObjectExpr(PseudoObjectExpr * POE)1424     void VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
1425       // Only need to visit the semantics for POE.
1426       // SyntaticForm doesn't really use the Decal.
1427       for (auto *S : POE->semantics()) {
1428         if (auto *OVE = dyn_cast<OpaqueValueExpr>(S))
1429           // Look past the OVE into the expression it binds.
1430           Visit(OVE->getSourceExpr());
1431         else
1432           Visit(S);
1433       }
1434     }
1435 
FoundDeclInUse()1436     bool FoundDeclInUse() { return FoundDecl; }
1437 
1438   };  // end class DeclMatcher
1439 
CheckForLoopConditionalStatement(Sema & S,Expr * Second,Expr * Third,Stmt * Body)1440   void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
1441                                         Expr *Third, Stmt *Body) {
1442     // Condition is empty
1443     if (!Second) return;
1444 
1445     if (S.Diags.isIgnored(diag::warn_variables_not_in_loop_body,
1446                           Second->getLocStart()))
1447       return;
1448 
1449     PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body);
1450     llvm::SmallPtrSet<VarDecl*, 8> Decls;
1451     SmallVector<SourceRange, 10> Ranges;
1452     DeclExtractor DE(S, Decls, Ranges);
1453     DE.Visit(Second);
1454 
1455     // Don't analyze complex conditionals.
1456     if (!DE.isSimple()) return;
1457 
1458     // No decls found.
1459     if (Decls.size() == 0) return;
1460 
1461     // Don't warn on volatile, static, or global variables.
1462     for (llvm::SmallPtrSetImpl<VarDecl*>::iterator I = Decls.begin(),
1463                                                    E = Decls.end();
1464          I != E; ++I)
1465       if ((*I)->getType().isVolatileQualified() ||
1466           (*I)->hasGlobalStorage()) return;
1467 
1468     if (DeclMatcher(S, Decls, Second).FoundDeclInUse() ||
1469         DeclMatcher(S, Decls, Third).FoundDeclInUse() ||
1470         DeclMatcher(S, Decls, Body).FoundDeclInUse())
1471       return;
1472 
1473     // Load decl names into diagnostic.
1474     if (Decls.size() > 4)
1475       PDiag << 0;
1476     else {
1477       PDiag << Decls.size();
1478       for (llvm::SmallPtrSetImpl<VarDecl*>::iterator I = Decls.begin(),
1479                                                      E = Decls.end();
1480            I != E; ++I)
1481         PDiag << (*I)->getDeclName();
1482     }
1483 
1484     // Load SourceRanges into diagnostic if there is room.
1485     // Otherwise, load the SourceRange of the conditional expression.
1486     if (Ranges.size() <= PartialDiagnostic::MaxArguments)
1487       for (SmallVectorImpl<SourceRange>::iterator I = Ranges.begin(),
1488                                                   E = Ranges.end();
1489            I != E; ++I)
1490         PDiag << *I;
1491     else
1492       PDiag << Second->getSourceRange();
1493 
1494     S.Diag(Ranges.begin()->getBegin(), PDiag);
1495   }
1496 
1497   // If Statement is an incemement or decrement, return true and sets the
1498   // variables Increment and DRE.
ProcessIterationStmt(Sema & S,Stmt * Statement,bool & Increment,DeclRefExpr * & DRE)1499   bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment,
1500                             DeclRefExpr *&DRE) {
1501     if (auto Cleanups = dyn_cast<ExprWithCleanups>(Statement))
1502       if (!Cleanups->cleanupsHaveSideEffects())
1503         Statement = Cleanups->getSubExpr();
1504 
1505     if (UnaryOperator *UO = dyn_cast<UnaryOperator>(Statement)) {
1506       switch (UO->getOpcode()) {
1507         default: return false;
1508         case UO_PostInc:
1509         case UO_PreInc:
1510           Increment = true;
1511           break;
1512         case UO_PostDec:
1513         case UO_PreDec:
1514           Increment = false;
1515           break;
1516       }
1517       DRE = dyn_cast<DeclRefExpr>(UO->getSubExpr());
1518       return DRE;
1519     }
1520 
1521     if (CXXOperatorCallExpr *Call = dyn_cast<CXXOperatorCallExpr>(Statement)) {
1522       FunctionDecl *FD = Call->getDirectCallee();
1523       if (!FD || !FD->isOverloadedOperator()) return false;
1524       switch (FD->getOverloadedOperator()) {
1525         default: return false;
1526         case OO_PlusPlus:
1527           Increment = true;
1528           break;
1529         case OO_MinusMinus:
1530           Increment = false;
1531           break;
1532       }
1533       DRE = dyn_cast<DeclRefExpr>(Call->getArg(0));
1534       return DRE;
1535     }
1536 
1537     return false;
1538   }
1539 
1540   // A visitor to determine if a continue or break statement is a
1541   // subexpression.
1542   class BreakContinueFinder : public EvaluatedExprVisitor<BreakContinueFinder> {
1543     SourceLocation BreakLoc;
1544     SourceLocation ContinueLoc;
1545   public:
BreakContinueFinder(Sema & S,Stmt * Body)1546     BreakContinueFinder(Sema &S, Stmt* Body) :
1547         Inherited(S.Context) {
1548       Visit(Body);
1549     }
1550 
1551     typedef EvaluatedExprVisitor<BreakContinueFinder> Inherited;
1552 
VisitContinueStmt(ContinueStmt * E)1553     void VisitContinueStmt(ContinueStmt* E) {
1554       ContinueLoc = E->getContinueLoc();
1555     }
1556 
VisitBreakStmt(BreakStmt * E)1557     void VisitBreakStmt(BreakStmt* E) {
1558       BreakLoc = E->getBreakLoc();
1559     }
1560 
ContinueFound()1561     bool ContinueFound() { return ContinueLoc.isValid(); }
BreakFound()1562     bool BreakFound() { return BreakLoc.isValid(); }
GetContinueLoc()1563     SourceLocation GetContinueLoc() { return ContinueLoc; }
GetBreakLoc()1564     SourceLocation GetBreakLoc() { return BreakLoc; }
1565 
1566   };  // end class BreakContinueFinder
1567 
1568   // Emit a warning when a loop increment/decrement appears twice per loop
1569   // iteration.  The conditions which trigger this warning are:
1570   // 1) The last statement in the loop body and the third expression in the
1571   //    for loop are both increment or both decrement of the same variable
1572   // 2) No continue statements in the loop body.
CheckForRedundantIteration(Sema & S,Expr * Third,Stmt * Body)1573   void CheckForRedundantIteration(Sema &S, Expr *Third, Stmt *Body) {
1574     // Return when there is nothing to check.
1575     if (!Body || !Third) return;
1576 
1577     if (S.Diags.isIgnored(diag::warn_redundant_loop_iteration,
1578                           Third->getLocStart()))
1579       return;
1580 
1581     // Get the last statement from the loop body.
1582     CompoundStmt *CS = dyn_cast<CompoundStmt>(Body);
1583     if (!CS || CS->body_empty()) return;
1584     Stmt *LastStmt = CS->body_back();
1585     if (!LastStmt) return;
1586 
1587     bool LoopIncrement, LastIncrement;
1588     DeclRefExpr *LoopDRE, *LastDRE;
1589 
1590     if (!ProcessIterationStmt(S, Third, LoopIncrement, LoopDRE)) return;
1591     if (!ProcessIterationStmt(S, LastStmt, LastIncrement, LastDRE)) return;
1592 
1593     // Check that the two statements are both increments or both decrements
1594     // on the same variable.
1595     if (LoopIncrement != LastIncrement ||
1596         LoopDRE->getDecl() != LastDRE->getDecl()) return;
1597 
1598     if (BreakContinueFinder(S, Body).ContinueFound()) return;
1599 
1600     S.Diag(LastDRE->getLocation(), diag::warn_redundant_loop_iteration)
1601          << LastDRE->getDecl() << LastIncrement;
1602     S.Diag(LoopDRE->getLocation(), diag::note_loop_iteration_here)
1603          << LoopIncrement;
1604   }
1605 
1606 } // end namespace
1607 
1608 
CheckBreakContinueBinding(Expr * E)1609 void Sema::CheckBreakContinueBinding(Expr *E) {
1610   if (!E || getLangOpts().CPlusPlus)
1611     return;
1612   BreakContinueFinder BCFinder(*this, E);
1613   Scope *BreakParent = CurScope->getBreakParent();
1614   if (BCFinder.BreakFound() && BreakParent) {
1615     if (BreakParent->getFlags() & Scope::SwitchScope) {
1616       Diag(BCFinder.GetBreakLoc(), diag::warn_break_binds_to_switch);
1617     } else {
1618       Diag(BCFinder.GetBreakLoc(), diag::warn_loop_ctrl_binds_to_inner)
1619           << "break";
1620     }
1621   } else if (BCFinder.ContinueFound() && CurScope->getContinueParent()) {
1622     Diag(BCFinder.GetContinueLoc(), diag::warn_loop_ctrl_binds_to_inner)
1623         << "continue";
1624   }
1625 }
1626 
ActOnForStmt(SourceLocation ForLoc,SourceLocation LParenLoc,Stmt * First,ConditionResult Second,FullExprArg third,SourceLocation RParenLoc,Stmt * Body)1627 StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
1628                               Stmt *First, ConditionResult Second,
1629                               FullExprArg third, SourceLocation RParenLoc,
1630                               Stmt *Body) {
1631   if (Second.isInvalid())
1632     return StmtError();
1633 
1634   if (!getLangOpts().CPlusPlus) {
1635     if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
1636       // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1637       // declare identifiers for objects having storage class 'auto' or
1638       // 'register'.
1639       for (auto *DI : DS->decls()) {
1640         VarDecl *VD = dyn_cast<VarDecl>(DI);
1641         if (VD && VD->isLocalVarDecl() && !VD->hasLocalStorage())
1642           VD = nullptr;
1643         if (!VD) {
1644           Diag(DI->getLocation(), diag::err_non_local_variable_decl_in_for);
1645           DI->setInvalidDecl();
1646         }
1647       }
1648     }
1649   }
1650 
1651   CheckBreakContinueBinding(Second.get().second);
1652   CheckBreakContinueBinding(third.get());
1653 
1654   if (!Second.get().first)
1655     CheckForLoopConditionalStatement(*this, Second.get().second, third.get(),
1656                                      Body);
1657   CheckForRedundantIteration(*this, third.get(), Body);
1658 
1659   if (Second.get().second &&
1660       !Diags.isIgnored(diag::warn_comma_operator,
1661                        Second.get().second->getExprLoc()))
1662     CommaVisitor(*this).Visit(Second.get().second);
1663 
1664   Expr *Third  = third.release().getAs<Expr>();
1665 
1666   DiagnoseUnusedExprResult(First);
1667   DiagnoseUnusedExprResult(Third);
1668   DiagnoseUnusedExprResult(Body);
1669 
1670   if (isa<NullStmt>(Body))
1671     getCurCompoundScope().setHasEmptyLoopBodies();
1672 
1673   return new (Context)
1674       ForStmt(Context, First, Second.get().second, Second.get().first, Third,
1675               Body, ForLoc, LParenLoc, RParenLoc);
1676 }
1677 
1678 /// In an Objective C collection iteration statement:
1679 ///   for (x in y)
1680 /// x can be an arbitrary l-value expression.  Bind it up as a
1681 /// full-expression.
ActOnForEachLValueExpr(Expr * E)1682 StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
1683   // Reduce placeholder expressions here.  Note that this rejects the
1684   // use of pseudo-object l-values in this position.
1685   ExprResult result = CheckPlaceholderExpr(E);
1686   if (result.isInvalid()) return StmtError();
1687   E = result.get();
1688 
1689   ExprResult FullExpr = ActOnFinishFullExpr(E);
1690   if (FullExpr.isInvalid())
1691     return StmtError();
1692   return StmtResult(static_cast<Stmt*>(FullExpr.get()));
1693 }
1694 
1695 ExprResult
CheckObjCForCollectionOperand(SourceLocation forLoc,Expr * collection)1696 Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) {
1697   if (!collection)
1698     return ExprError();
1699 
1700   ExprResult result = CorrectDelayedTyposInExpr(collection);
1701   if (!result.isUsable())
1702     return ExprError();
1703   collection = result.get();
1704 
1705   // Bail out early if we've got a type-dependent expression.
1706   if (collection->isTypeDependent()) return collection;
1707 
1708   // Perform normal l-value conversion.
1709   result = DefaultFunctionArrayLvalueConversion(collection);
1710   if (result.isInvalid())
1711     return ExprError();
1712   collection = result.get();
1713 
1714   // The operand needs to have object-pointer type.
1715   // TODO: should we do a contextual conversion?
1716   const ObjCObjectPointerType *pointerType =
1717     collection->getType()->getAs<ObjCObjectPointerType>();
1718   if (!pointerType)
1719     return Diag(forLoc, diag::err_collection_expr_type)
1720              << collection->getType() << collection->getSourceRange();
1721 
1722   // Check that the operand provides
1723   //   - countByEnumeratingWithState:objects:count:
1724   const ObjCObjectType *objectType = pointerType->getObjectType();
1725   ObjCInterfaceDecl *iface = objectType->getInterface();
1726 
1727   // If we have a forward-declared type, we can't do this check.
1728   // Under ARC, it is an error not to have a forward-declared class.
1729   if (iface &&
1730       (getLangOpts().ObjCAutoRefCount
1731            ? RequireCompleteType(forLoc, QualType(objectType, 0),
1732                                  diag::err_arc_collection_forward, collection)
1733            : !isCompleteType(forLoc, QualType(objectType, 0)))) {
1734     // Otherwise, if we have any useful type information, check that
1735     // the type declares the appropriate method.
1736   } else if (iface || !objectType->qual_empty()) {
1737     IdentifierInfo *selectorIdents[] = {
1738       &Context.Idents.get("countByEnumeratingWithState"),
1739       &Context.Idents.get("objects"),
1740       &Context.Idents.get("count")
1741     };
1742     Selector selector = Context.Selectors.getSelector(3, &selectorIdents[0]);
1743 
1744     ObjCMethodDecl *method = nullptr;
1745 
1746     // If there's an interface, look in both the public and private APIs.
1747     if (iface) {
1748       method = iface->lookupInstanceMethod(selector);
1749       if (!method) method = iface->lookupPrivateMethod(selector);
1750     }
1751 
1752     // Also check protocol qualifiers.
1753     if (!method)
1754       method = LookupMethodInQualifiedType(selector, pointerType,
1755                                            /*instance*/ true);
1756 
1757     // If we didn't find it anywhere, give up.
1758     if (!method) {
1759       Diag(forLoc, diag::warn_collection_expr_type)
1760         << collection->getType() << selector << collection->getSourceRange();
1761     }
1762 
1763     // TODO: check for an incompatible signature?
1764   }
1765 
1766   // Wrap up any cleanups in the expression.
1767   return collection;
1768 }
1769 
1770 StmtResult
ActOnObjCForCollectionStmt(SourceLocation ForLoc,Stmt * First,Expr * collection,SourceLocation RParenLoc)1771 Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
1772                                  Stmt *First, Expr *collection,
1773                                  SourceLocation RParenLoc) {
1774 
1775   ExprResult CollectionExprResult =
1776     CheckObjCForCollectionOperand(ForLoc, collection);
1777 
1778   if (First) {
1779     QualType FirstType;
1780     if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
1781       if (!DS->isSingleDecl())
1782         return StmtError(Diag((*DS->decl_begin())->getLocation(),
1783                          diag::err_toomany_element_decls));
1784 
1785       VarDecl *D = dyn_cast<VarDecl>(DS->getSingleDecl());
1786       if (!D || D->isInvalidDecl())
1787         return StmtError();
1788 
1789       FirstType = D->getType();
1790       // C99 6.8.5p3: The declaration part of a 'for' statement shall only
1791       // declare identifiers for objects having storage class 'auto' or
1792       // 'register'.
1793       if (!D->hasLocalStorage())
1794         return StmtError(Diag(D->getLocation(),
1795                               diag::err_non_local_variable_decl_in_for));
1796 
1797       // If the type contained 'auto', deduce the 'auto' to 'id'.
1798       if (FirstType->getContainedAutoType()) {
1799         OpaqueValueExpr OpaqueId(D->getLocation(), Context.getObjCIdType(),
1800                                  VK_RValue);
1801         Expr *DeducedInit = &OpaqueId;
1802         if (DeduceAutoType(D->getTypeSourceInfo(), DeducedInit, FirstType) ==
1803                 DAR_Failed)
1804           DiagnoseAutoDeductionFailure(D, DeducedInit);
1805         if (FirstType.isNull()) {
1806           D->setInvalidDecl();
1807           return StmtError();
1808         }
1809 
1810         D->setType(FirstType);
1811 
1812         if (ActiveTemplateInstantiations.empty()) {
1813           SourceLocation Loc =
1814               D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
1815           Diag(Loc, diag::warn_auto_var_is_id)
1816             << D->getDeclName();
1817         }
1818       }
1819 
1820     } else {
1821       Expr *FirstE = cast<Expr>(First);
1822       if (!FirstE->isTypeDependent() && !FirstE->isLValue())
1823         return StmtError(Diag(First->getLocStart(),
1824                    diag::err_selector_element_not_lvalue)
1825           << First->getSourceRange());
1826 
1827       FirstType = static_cast<Expr*>(First)->getType();
1828       if (FirstType.isConstQualified())
1829         Diag(ForLoc, diag::err_selector_element_const_type)
1830           << FirstType << First->getSourceRange();
1831     }
1832     if (!FirstType->isDependentType() &&
1833         !FirstType->isObjCObjectPointerType() &&
1834         !FirstType->isBlockPointerType())
1835         return StmtError(Diag(ForLoc, diag::err_selector_element_type)
1836                            << FirstType << First->getSourceRange());
1837   }
1838 
1839   if (CollectionExprResult.isInvalid())
1840     return StmtError();
1841 
1842   CollectionExprResult = ActOnFinishFullExpr(CollectionExprResult.get());
1843   if (CollectionExprResult.isInvalid())
1844     return StmtError();
1845 
1846   return new (Context) ObjCForCollectionStmt(First, CollectionExprResult.get(),
1847                                              nullptr, ForLoc, RParenLoc);
1848 }
1849 
1850 /// Finish building a variable declaration for a for-range statement.
1851 /// \return true if an error occurs.
FinishForRangeVarDecl(Sema & SemaRef,VarDecl * Decl,Expr * Init,SourceLocation Loc,int DiagID)1852 static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
1853                                   SourceLocation Loc, int DiagID) {
1854   if (Decl->getType()->isUndeducedType()) {
1855     ExprResult Res = SemaRef.CorrectDelayedTyposInExpr(Init);
1856     if (!Res.isUsable()) {
1857       Decl->setInvalidDecl();
1858       return true;
1859     }
1860     Init = Res.get();
1861   }
1862 
1863   // Deduce the type for the iterator variable now rather than leaving it to
1864   // AddInitializerToDecl, so we can produce a more suitable diagnostic.
1865   QualType InitType;
1866   if ((!isa<InitListExpr>(Init) && Init->getType()->isVoidType()) ||
1867       SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitType) ==
1868           Sema::DAR_Failed)
1869     SemaRef.Diag(Loc, DiagID) << Init->getType();
1870   if (InitType.isNull()) {
1871     Decl->setInvalidDecl();
1872     return true;
1873   }
1874   Decl->setType(InitType);
1875 
1876   // In ARC, infer lifetime.
1877   // FIXME: ARC may want to turn this into 'const __unsafe_unretained' if
1878   // we're doing the equivalent of fast iteration.
1879   if (SemaRef.getLangOpts().ObjCAutoRefCount &&
1880       SemaRef.inferObjCARCLifetime(Decl))
1881     Decl->setInvalidDecl();
1882 
1883   SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false,
1884                                /*TypeMayContainAuto=*/false);
1885   SemaRef.FinalizeDeclaration(Decl);
1886   SemaRef.CurContext->addHiddenDecl(Decl);
1887   return false;
1888 }
1889 
1890 namespace {
1891 // An enum to represent whether something is dealing with a call to begin()
1892 // or a call to end() in a range-based for loop.
1893 enum BeginEndFunction {
1894   BEF_begin,
1895   BEF_end
1896 };
1897 
1898 /// Produce a note indicating which begin/end function was implicitly called
1899 /// by a C++11 for-range statement. This is often not obvious from the code,
1900 /// nor from the diagnostics produced when analysing the implicit expressions
1901 /// required in a for-range statement.
NoteForRangeBeginEndFunction(Sema & SemaRef,Expr * E,BeginEndFunction BEF)1902 void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
1903                                   BeginEndFunction BEF) {
1904   CallExpr *CE = dyn_cast<CallExpr>(E);
1905   if (!CE)
1906     return;
1907   FunctionDecl *D = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1908   if (!D)
1909     return;
1910   SourceLocation Loc = D->getLocation();
1911 
1912   std::string Description;
1913   bool IsTemplate = false;
1914   if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) {
1915     Description = SemaRef.getTemplateArgumentBindingsText(
1916       FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs());
1917     IsTemplate = true;
1918   }
1919 
1920   SemaRef.Diag(Loc, diag::note_for_range_begin_end)
1921     << BEF << IsTemplate << Description << E->getType();
1922 }
1923 
1924 /// Build a variable declaration for a for-range statement.
BuildForRangeVarDecl(Sema & SemaRef,SourceLocation Loc,QualType Type,const char * Name)1925 VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
1926                               QualType Type, const char *Name) {
1927   DeclContext *DC = SemaRef.CurContext;
1928   IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
1929   TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc);
1930   VarDecl *Decl = VarDecl::Create(SemaRef.Context, DC, Loc, Loc, II, Type,
1931                                   TInfo, SC_None);
1932   Decl->setImplicit();
1933   return Decl;
1934 }
1935 
1936 }
1937 
ObjCEnumerationCollection(Expr * Collection)1938 static bool ObjCEnumerationCollection(Expr *Collection) {
1939   return !Collection->isTypeDependent()
1940           && Collection->getType()->getAs<ObjCObjectPointerType>() != nullptr;
1941 }
1942 
1943 /// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement.
1944 ///
1945 /// C++11 [stmt.ranged]:
1946 ///   A range-based for statement is equivalent to
1947 ///
1948 ///   {
1949 ///     auto && __range = range-init;
1950 ///     for ( auto __begin = begin-expr,
1951 ///           __end = end-expr;
1952 ///           __begin != __end;
1953 ///           ++__begin ) {
1954 ///       for-range-declaration = *__begin;
1955 ///       statement
1956 ///     }
1957 ///   }
1958 ///
1959 /// The body of the loop is not available yet, since it cannot be analysed until
1960 /// we have determined the type of the for-range-declaration.
ActOnCXXForRangeStmt(Scope * S,SourceLocation ForLoc,SourceLocation CoawaitLoc,Stmt * First,SourceLocation ColonLoc,Expr * Range,SourceLocation RParenLoc,BuildForRangeKind Kind)1961 StmtResult Sema::ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc,
1962                                       SourceLocation CoawaitLoc, Stmt *First,
1963                                       SourceLocation ColonLoc, Expr *Range,
1964                                       SourceLocation RParenLoc,
1965                                       BuildForRangeKind Kind) {
1966   if (!First)
1967     return StmtError();
1968 
1969   if (Range && ObjCEnumerationCollection(Range))
1970     return ActOnObjCForCollectionStmt(ForLoc, First, Range, RParenLoc);
1971 
1972   DeclStmt *DS = dyn_cast<DeclStmt>(First);
1973   assert(DS && "first part of for range not a decl stmt");
1974 
1975   if (!DS->isSingleDecl()) {
1976     Diag(DS->getStartLoc(), diag::err_type_defined_in_for_range);
1977     return StmtError();
1978   }
1979 
1980   Decl *LoopVar = DS->getSingleDecl();
1981   if (LoopVar->isInvalidDecl() || !Range ||
1982       DiagnoseUnexpandedParameterPack(Range, UPPC_Expression)) {
1983     LoopVar->setInvalidDecl();
1984     return StmtError();
1985   }
1986 
1987   // Coroutines: 'for co_await' implicitly co_awaits its range.
1988   if (CoawaitLoc.isValid()) {
1989     ExprResult Coawait = ActOnCoawaitExpr(S, CoawaitLoc, Range);
1990     if (Coawait.isInvalid()) return StmtError();
1991     Range = Coawait.get();
1992   }
1993 
1994   // Build  auto && __range = range-init
1995   SourceLocation RangeLoc = Range->getLocStart();
1996   VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc,
1997                                            Context.getAutoRRefDeductType(),
1998                                            "__range");
1999   if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
2000                             diag::err_for_range_deduction_failure)) {
2001     LoopVar->setInvalidDecl();
2002     return StmtError();
2003   }
2004 
2005   // Claim the type doesn't contain auto: we've already done the checking.
2006   DeclGroupPtrTy RangeGroup =
2007       BuildDeclaratorGroup(MutableArrayRef<Decl *>((Decl **)&RangeVar, 1),
2008                            /*TypeMayContainAuto=*/ false);
2009   StmtResult RangeDecl = ActOnDeclStmt(RangeGroup, RangeLoc, RangeLoc);
2010   if (RangeDecl.isInvalid()) {
2011     LoopVar->setInvalidDecl();
2012     return StmtError();
2013   }
2014 
2015   return BuildCXXForRangeStmt(ForLoc, CoawaitLoc, ColonLoc, RangeDecl.get(),
2016                               /*BeginStmt=*/nullptr, /*EndStmt=*/nullptr,
2017                               /*Cond=*/nullptr, /*Inc=*/nullptr,
2018                               DS, RParenLoc, Kind);
2019 }
2020 
2021 /// \brief Create the initialization, compare, and increment steps for
2022 /// the range-based for loop expression.
2023 /// This function does not handle array-based for loops,
2024 /// which are created in Sema::BuildCXXForRangeStmt.
2025 ///
2026 /// \returns a ForRangeStatus indicating success or what kind of error occurred.
2027 /// BeginExpr and EndExpr are set and FRS_Success is returned on success;
2028 /// CandidateSet and BEF are set and some non-success value is returned on
2029 /// failure.
BuildNonArrayForRange(Sema & SemaRef,Expr * BeginRange,Expr * EndRange,QualType RangeType,VarDecl * BeginVar,VarDecl * EndVar,SourceLocation ColonLoc,OverloadCandidateSet * CandidateSet,ExprResult * BeginExpr,ExprResult * EndExpr,BeginEndFunction * BEF)2030 static Sema::ForRangeStatus BuildNonArrayForRange(Sema &SemaRef,
2031                                             Expr *BeginRange, Expr *EndRange,
2032                                             QualType RangeType,
2033                                             VarDecl *BeginVar,
2034                                             VarDecl *EndVar,
2035                                             SourceLocation ColonLoc,
2036                                             OverloadCandidateSet *CandidateSet,
2037                                             ExprResult *BeginExpr,
2038                                             ExprResult *EndExpr,
2039                                             BeginEndFunction *BEF) {
2040   DeclarationNameInfo BeginNameInfo(
2041       &SemaRef.PP.getIdentifierTable().get("begin"), ColonLoc);
2042   DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get("end"),
2043                                   ColonLoc);
2044 
2045   LookupResult BeginMemberLookup(SemaRef, BeginNameInfo,
2046                                  Sema::LookupMemberName);
2047   LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName);
2048 
2049   if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) {
2050     // - if _RangeT is a class type, the unqualified-ids begin and end are
2051     //   looked up in the scope of class _RangeT as if by class member access
2052     //   lookup (3.4.5), and if either (or both) finds at least one
2053     //   declaration, begin-expr and end-expr are __range.begin() and
2054     //   __range.end(), respectively;
2055     SemaRef.LookupQualifiedName(BeginMemberLookup, D);
2056     SemaRef.LookupQualifiedName(EndMemberLookup, D);
2057 
2058     if (BeginMemberLookup.empty() != EndMemberLookup.empty()) {
2059       SourceLocation RangeLoc = BeginVar->getLocation();
2060       *BEF = BeginMemberLookup.empty() ? BEF_end : BEF_begin;
2061 
2062       SemaRef.Diag(RangeLoc, diag::err_for_range_member_begin_end_mismatch)
2063           << RangeLoc << BeginRange->getType() << *BEF;
2064       return Sema::FRS_DiagnosticIssued;
2065     }
2066   } else {
2067     // - otherwise, begin-expr and end-expr are begin(__range) and
2068     //   end(__range), respectively, where begin and end are looked up with
2069     //   argument-dependent lookup (3.4.2). For the purposes of this name
2070     //   lookup, namespace std is an associated namespace.
2071 
2072   }
2073 
2074   *BEF = BEF_begin;
2075   Sema::ForRangeStatus RangeStatus =
2076       SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, BeginNameInfo,
2077                                         BeginMemberLookup, CandidateSet,
2078                                         BeginRange, BeginExpr);
2079 
2080   if (RangeStatus != Sema::FRS_Success) {
2081     if (RangeStatus == Sema::FRS_DiagnosticIssued)
2082       SemaRef.Diag(BeginRange->getLocStart(), diag::note_in_for_range)
2083           << ColonLoc << BEF_begin << BeginRange->getType();
2084     return RangeStatus;
2085   }
2086   if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc,
2087                             diag::err_for_range_iter_deduction_failure)) {
2088     NoteForRangeBeginEndFunction(SemaRef, BeginExpr->get(), *BEF);
2089     return Sema::FRS_DiagnosticIssued;
2090   }
2091 
2092   *BEF = BEF_end;
2093   RangeStatus =
2094       SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, EndNameInfo,
2095                                         EndMemberLookup, CandidateSet,
2096                                         EndRange, EndExpr);
2097   if (RangeStatus != Sema::FRS_Success) {
2098     if (RangeStatus == Sema::FRS_DiagnosticIssued)
2099       SemaRef.Diag(EndRange->getLocStart(), diag::note_in_for_range)
2100           << ColonLoc << BEF_end << EndRange->getType();
2101     return RangeStatus;
2102   }
2103   if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc,
2104                             diag::err_for_range_iter_deduction_failure)) {
2105     NoteForRangeBeginEndFunction(SemaRef, EndExpr->get(), *BEF);
2106     return Sema::FRS_DiagnosticIssued;
2107   }
2108   return Sema::FRS_Success;
2109 }
2110 
2111 /// Speculatively attempt to dereference an invalid range expression.
2112 /// If the attempt fails, this function will return a valid, null StmtResult
2113 /// and emit no diagnostics.
RebuildForRangeWithDereference(Sema & SemaRef,Scope * S,SourceLocation ForLoc,SourceLocation CoawaitLoc,Stmt * LoopVarDecl,SourceLocation ColonLoc,Expr * Range,SourceLocation RangeLoc,SourceLocation RParenLoc)2114 static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S,
2115                                                  SourceLocation ForLoc,
2116                                                  SourceLocation CoawaitLoc,
2117                                                  Stmt *LoopVarDecl,
2118                                                  SourceLocation ColonLoc,
2119                                                  Expr *Range,
2120                                                  SourceLocation RangeLoc,
2121                                                  SourceLocation RParenLoc) {
2122   // Determine whether we can rebuild the for-range statement with a
2123   // dereferenced range expression.
2124   ExprResult AdjustedRange;
2125   {
2126     Sema::SFINAETrap Trap(SemaRef);
2127 
2128     AdjustedRange = SemaRef.BuildUnaryOp(S, RangeLoc, UO_Deref, Range);
2129     if (AdjustedRange.isInvalid())
2130       return StmtResult();
2131 
2132     StmtResult SR = SemaRef.ActOnCXXForRangeStmt(
2133         S, ForLoc, CoawaitLoc, LoopVarDecl, ColonLoc, AdjustedRange.get(),
2134         RParenLoc, Sema::BFRK_Check);
2135     if (SR.isInvalid())
2136       return StmtResult();
2137   }
2138 
2139   // The attempt to dereference worked well enough that it could produce a valid
2140   // loop. Produce a fixit, and rebuild the loop with diagnostics enabled, in
2141   // case there are any other (non-fatal) problems with it.
2142   SemaRef.Diag(RangeLoc, diag::err_for_range_dereference)
2143     << Range->getType() << FixItHint::CreateInsertion(RangeLoc, "*");
2144   return SemaRef.ActOnCXXForRangeStmt(S, ForLoc, CoawaitLoc, LoopVarDecl,
2145                                       ColonLoc, AdjustedRange.get(), RParenLoc,
2146                                       Sema::BFRK_Rebuild);
2147 }
2148 
2149 namespace {
2150 /// RAII object to automatically invalidate a declaration if an error occurs.
2151 struct InvalidateOnErrorScope {
InvalidateOnErrorScope__anon27b5dcff0611::InvalidateOnErrorScope2152   InvalidateOnErrorScope(Sema &SemaRef, Decl *D, bool Enabled)
2153       : Trap(SemaRef.Diags), D(D), Enabled(Enabled) {}
~InvalidateOnErrorScope__anon27b5dcff0611::InvalidateOnErrorScope2154   ~InvalidateOnErrorScope() {
2155     if (Enabled && Trap.hasErrorOccurred())
2156       D->setInvalidDecl();
2157   }
2158 
2159   DiagnosticErrorTrap Trap;
2160   Decl *D;
2161   bool Enabled;
2162 };
2163 }
2164 
2165 /// BuildCXXForRangeStmt - Build or instantiate a C++11 for-range statement.
2166 StmtResult
BuildCXXForRangeStmt(SourceLocation ForLoc,SourceLocation CoawaitLoc,SourceLocation ColonLoc,Stmt * RangeDecl,Stmt * Begin,Stmt * End,Expr * Cond,Expr * Inc,Stmt * LoopVarDecl,SourceLocation RParenLoc,BuildForRangeKind Kind)2167 Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation CoawaitLoc,
2168                            SourceLocation ColonLoc, Stmt *RangeDecl,
2169                            Stmt *Begin, Stmt *End, Expr *Cond,
2170                            Expr *Inc, Stmt *LoopVarDecl,
2171                            SourceLocation RParenLoc, BuildForRangeKind Kind) {
2172   // FIXME: This should not be used during template instantiation. We should
2173   // pick up the set of unqualified lookup results for the != and + operators
2174   // in the initial parse.
2175   //
2176   // Testcase (accepts-invalid):
2177   //   template<typename T> void f() { for (auto x : T()) {} }
2178   //   namespace N { struct X { X begin(); X end(); int operator*(); }; }
2179   //   bool operator!=(N::X, N::X); void operator++(N::X);
2180   //   void g() { f<N::X>(); }
2181   Scope *S = getCurScope();
2182 
2183   DeclStmt *RangeDS = cast<DeclStmt>(RangeDecl);
2184   VarDecl *RangeVar = cast<VarDecl>(RangeDS->getSingleDecl());
2185   QualType RangeVarType = RangeVar->getType();
2186 
2187   DeclStmt *LoopVarDS = cast<DeclStmt>(LoopVarDecl);
2188   VarDecl *LoopVar = cast<VarDecl>(LoopVarDS->getSingleDecl());
2189 
2190   // If we hit any errors, mark the loop variable as invalid if its type
2191   // contains 'auto'.
2192   InvalidateOnErrorScope Invalidate(*this, LoopVar,
2193                                     LoopVar->getType()->isUndeducedType());
2194 
2195   StmtResult BeginDeclStmt = Begin;
2196   StmtResult EndDeclStmt = End;
2197   ExprResult NotEqExpr = Cond, IncrExpr = Inc;
2198 
2199   if (RangeVarType->isDependentType()) {
2200     // The range is implicitly used as a placeholder when it is dependent.
2201     RangeVar->markUsed(Context);
2202 
2203     // Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill
2204     // them in properly when we instantiate the loop.
2205     if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check)
2206       LoopVar->setType(SubstAutoType(LoopVar->getType(), Context.DependentTy));
2207   } else if (!BeginDeclStmt.get()) {
2208     SourceLocation RangeLoc = RangeVar->getLocation();
2209 
2210     const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
2211 
2212     ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2213                                                 VK_LValue, ColonLoc);
2214     if (BeginRangeRef.isInvalid())
2215       return StmtError();
2216 
2217     ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2218                                               VK_LValue, ColonLoc);
2219     if (EndRangeRef.isInvalid())
2220       return StmtError();
2221 
2222     QualType AutoType = Context.getAutoDeductType();
2223     Expr *Range = RangeVar->getInit();
2224     if (!Range)
2225       return StmtError();
2226     QualType RangeType = Range->getType();
2227 
2228     if (RequireCompleteType(RangeLoc, RangeType,
2229                             diag::err_for_range_incomplete_type))
2230       return StmtError();
2231 
2232     // Build auto __begin = begin-expr, __end = end-expr.
2233     VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2234                                              "__begin");
2235     VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2236                                            "__end");
2237 
2238     // Build begin-expr and end-expr and attach to __begin and __end variables.
2239     ExprResult BeginExpr, EndExpr;
2240     if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) {
2241       // - if _RangeT is an array type, begin-expr and end-expr are __range and
2242       //   __range + __bound, respectively, where __bound is the array bound. If
2243       //   _RangeT is an array of unknown size or an array of incomplete type,
2244       //   the program is ill-formed;
2245 
2246       // begin-expr is __range.
2247       BeginExpr = BeginRangeRef;
2248       if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc,
2249                                 diag::err_for_range_iter_deduction_failure)) {
2250         NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2251         return StmtError();
2252       }
2253 
2254       // Find the array bound.
2255       ExprResult BoundExpr;
2256       if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(UnqAT))
2257         BoundExpr = IntegerLiteral::Create(
2258             Context, CAT->getSize(), Context.getPointerDiffType(), RangeLoc);
2259       else if (const VariableArrayType *VAT =
2260                dyn_cast<VariableArrayType>(UnqAT))
2261         BoundExpr = VAT->getSizeExpr();
2262       else {
2263         // Can't be a DependentSizedArrayType or an IncompleteArrayType since
2264         // UnqAT is not incomplete and Range is not type-dependent.
2265         llvm_unreachable("Unexpected array type in for-range");
2266       }
2267 
2268       // end-expr is __range + __bound.
2269       EndExpr = ActOnBinOp(S, ColonLoc, tok::plus, EndRangeRef.get(),
2270                            BoundExpr.get());
2271       if (EndExpr.isInvalid())
2272         return StmtError();
2273       if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc,
2274                                 diag::err_for_range_iter_deduction_failure)) {
2275         NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2276         return StmtError();
2277       }
2278     } else {
2279       OverloadCandidateSet CandidateSet(RangeLoc,
2280                                         OverloadCandidateSet::CSK_Normal);
2281       BeginEndFunction BEFFailure;
2282       ForRangeStatus RangeStatus =
2283           BuildNonArrayForRange(*this, BeginRangeRef.get(),
2284                                 EndRangeRef.get(), RangeType,
2285                                 BeginVar, EndVar, ColonLoc, &CandidateSet,
2286                                 &BeginExpr, &EndExpr, &BEFFailure);
2287 
2288       if (Kind == BFRK_Build && RangeStatus == FRS_NoViableFunction &&
2289           BEFFailure == BEF_begin) {
2290         // If the range is being built from an array parameter, emit a
2291         // a diagnostic that it is being treated as a pointer.
2292         if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Range)) {
2293           if (ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
2294             QualType ArrayTy = PVD->getOriginalType();
2295             QualType PointerTy = PVD->getType();
2296             if (PointerTy->isPointerType() && ArrayTy->isArrayType()) {
2297               Diag(Range->getLocStart(), diag::err_range_on_array_parameter)
2298                 << RangeLoc << PVD << ArrayTy << PointerTy;
2299               Diag(PVD->getLocation(), diag::note_declared_at);
2300               return StmtError();
2301             }
2302           }
2303         }
2304 
2305         // If building the range failed, try dereferencing the range expression
2306         // unless a diagnostic was issued or the end function is problematic.
2307         StmtResult SR = RebuildForRangeWithDereference(*this, S, ForLoc,
2308                                                        CoawaitLoc,
2309                                                        LoopVarDecl, ColonLoc,
2310                                                        Range, RangeLoc,
2311                                                        RParenLoc);
2312         if (SR.isInvalid() || SR.isUsable())
2313           return SR;
2314       }
2315 
2316       // Otherwise, emit diagnostics if we haven't already.
2317       if (RangeStatus == FRS_NoViableFunction) {
2318         Expr *Range = BEFFailure ? EndRangeRef.get() : BeginRangeRef.get();
2319         Diag(Range->getLocStart(), diag::err_for_range_invalid)
2320             << RangeLoc << Range->getType() << BEFFailure;
2321         CandidateSet.NoteCandidates(*this, OCD_AllCandidates, Range);
2322       }
2323       // Return an error if no fix was discovered.
2324       if (RangeStatus != FRS_Success)
2325         return StmtError();
2326     }
2327 
2328     assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() &&
2329            "invalid range expression in for loop");
2330 
2331     // C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same.
2332     // C++1z removes this restriction.
2333     QualType BeginType = BeginVar->getType(), EndType = EndVar->getType();
2334     if (!Context.hasSameType(BeginType, EndType)) {
2335       Diag(RangeLoc, getLangOpts().CPlusPlus1z
2336                          ? diag::warn_for_range_begin_end_types_differ
2337                          : diag::ext_for_range_begin_end_types_differ)
2338           << BeginType << EndType;
2339       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2340       NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2341     }
2342 
2343     BeginDeclStmt =
2344         ActOnDeclStmt(ConvertDeclToDeclGroup(BeginVar), ColonLoc, ColonLoc);
2345     EndDeclStmt =
2346         ActOnDeclStmt(ConvertDeclToDeclGroup(EndVar), ColonLoc, ColonLoc);
2347 
2348     const QualType BeginRefNonRefType = BeginType.getNonReferenceType();
2349     ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2350                                            VK_LValue, ColonLoc);
2351     if (BeginRef.isInvalid())
2352       return StmtError();
2353 
2354     ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(),
2355                                          VK_LValue, ColonLoc);
2356     if (EndRef.isInvalid())
2357       return StmtError();
2358 
2359     // Build and check __begin != __end expression.
2360     NotEqExpr = ActOnBinOp(S, ColonLoc, tok::exclaimequal,
2361                            BeginRef.get(), EndRef.get());
2362     if (!NotEqExpr.isInvalid())
2363       NotEqExpr = CheckBooleanCondition(ColonLoc, NotEqExpr.get());
2364     if (!NotEqExpr.isInvalid())
2365       NotEqExpr = ActOnFinishFullExpr(NotEqExpr.get());
2366     if (NotEqExpr.isInvalid()) {
2367       Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2368         << RangeLoc << 0 << BeginRangeRef.get()->getType();
2369       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2370       if (!Context.hasSameType(BeginType, EndType))
2371         NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2372       return StmtError();
2373     }
2374 
2375     // Build and check ++__begin expression.
2376     BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2377                                 VK_LValue, ColonLoc);
2378     if (BeginRef.isInvalid())
2379       return StmtError();
2380 
2381     IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get());
2382     if (!IncrExpr.isInvalid() && CoawaitLoc.isValid())
2383       IncrExpr = ActOnCoawaitExpr(S, CoawaitLoc, IncrExpr.get());
2384     if (!IncrExpr.isInvalid())
2385       IncrExpr = ActOnFinishFullExpr(IncrExpr.get());
2386     if (IncrExpr.isInvalid()) {
2387       Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2388         << RangeLoc << 2 << BeginRangeRef.get()->getType() ;
2389       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2390       return StmtError();
2391     }
2392 
2393     // Build and check *__begin  expression.
2394     BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2395                                 VK_LValue, ColonLoc);
2396     if (BeginRef.isInvalid())
2397       return StmtError();
2398 
2399     ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get());
2400     if (DerefExpr.isInvalid()) {
2401       Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2402         << RangeLoc << 1 << BeginRangeRef.get()->getType();
2403       NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2404       return StmtError();
2405     }
2406 
2407     // Attach  *__begin  as initializer for VD. Don't touch it if we're just
2408     // trying to determine whether this would be a valid range.
2409     if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
2410       AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false,
2411                            /*TypeMayContainAuto=*/true);
2412       if (LoopVar->isInvalidDecl())
2413         NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2414     }
2415   }
2416 
2417   // Don't bother to actually allocate the result if we're just trying to
2418   // determine whether it would be valid.
2419   if (Kind == BFRK_Check)
2420     return StmtResult();
2421 
2422   return new (Context) CXXForRangeStmt(
2423       RangeDS, cast_or_null<DeclStmt>(BeginDeclStmt.get()),
2424       cast_or_null<DeclStmt>(EndDeclStmt.get()), NotEqExpr.get(),
2425       IncrExpr.get(), LoopVarDS, /*Body=*/nullptr, ForLoc, CoawaitLoc,
2426       ColonLoc, RParenLoc);
2427 }
2428 
2429 /// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach
2430 /// statement.
FinishObjCForCollectionStmt(Stmt * S,Stmt * B)2431 StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) {
2432   if (!S || !B)
2433     return StmtError();
2434   ObjCForCollectionStmt * ForStmt = cast<ObjCForCollectionStmt>(S);
2435 
2436   ForStmt->setBody(B);
2437   return S;
2438 }
2439 
2440 // Warn when the loop variable is a const reference that creates a copy.
2441 // Suggest using the non-reference type for copies.  If a copy can be prevented
2442 // suggest the const reference type that would do so.
2443 // For instance, given "for (const &Foo : Range)", suggest
2444 // "for (const Foo : Range)" to denote a copy is made for the loop.  If
2445 // possible, also suggest "for (const &Bar : Range)" if this type prevents
2446 // the copy altogether.
DiagnoseForRangeReferenceVariableCopies(Sema & SemaRef,const VarDecl * VD,QualType RangeInitType)2447 static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef,
2448                                                     const VarDecl *VD,
2449                                                     QualType RangeInitType) {
2450   const Expr *InitExpr = VD->getInit();
2451   if (!InitExpr)
2452     return;
2453 
2454   QualType VariableType = VD->getType();
2455 
2456   if (auto Cleanups = dyn_cast<ExprWithCleanups>(InitExpr))
2457     if (!Cleanups->cleanupsHaveSideEffects())
2458       InitExpr = Cleanups->getSubExpr();
2459 
2460   const MaterializeTemporaryExpr *MTE =
2461       dyn_cast<MaterializeTemporaryExpr>(InitExpr);
2462 
2463   // No copy made.
2464   if (!MTE)
2465     return;
2466 
2467   const Expr *E = MTE->GetTemporaryExpr()->IgnoreImpCasts();
2468 
2469   // Searching for either UnaryOperator for dereference of a pointer or
2470   // CXXOperatorCallExpr for handling iterators.
2471   while (!isa<CXXOperatorCallExpr>(E) && !isa<UnaryOperator>(E)) {
2472     if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(E)) {
2473       E = CCE->getArg(0);
2474     } else if (const CXXMemberCallExpr *Call = dyn_cast<CXXMemberCallExpr>(E)) {
2475       const MemberExpr *ME = cast<MemberExpr>(Call->getCallee());
2476       E = ME->getBase();
2477     } else {
2478       const MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E);
2479       E = MTE->GetTemporaryExpr();
2480     }
2481     E = E->IgnoreImpCasts();
2482   }
2483 
2484   bool ReturnsReference = false;
2485   if (isa<UnaryOperator>(E)) {
2486     ReturnsReference = true;
2487   } else {
2488     const CXXOperatorCallExpr *Call = cast<CXXOperatorCallExpr>(E);
2489     const FunctionDecl *FD = Call->getDirectCallee();
2490     QualType ReturnType = FD->getReturnType();
2491     ReturnsReference = ReturnType->isReferenceType();
2492   }
2493 
2494   if (ReturnsReference) {
2495     // Loop variable creates a temporary.  Suggest either to go with
2496     // non-reference loop variable to indiciate a copy is made, or
2497     // the correct time to bind a const reference.
2498     SemaRef.Diag(VD->getLocation(), diag::warn_for_range_const_reference_copy)
2499         << VD << VariableType << E->getType();
2500     QualType NonReferenceType = VariableType.getNonReferenceType();
2501     NonReferenceType.removeLocalConst();
2502     QualType NewReferenceType =
2503         SemaRef.Context.getLValueReferenceType(E->getType().withConst());
2504     SemaRef.Diag(VD->getLocStart(), diag::note_use_type_or_non_reference)
2505         << NonReferenceType << NewReferenceType << VD->getSourceRange();
2506   } else {
2507     // The range always returns a copy, so a temporary is always created.
2508     // Suggest removing the reference from the loop variable.
2509     SemaRef.Diag(VD->getLocation(), diag::warn_for_range_variable_always_copy)
2510         << VD << RangeInitType;
2511     QualType NonReferenceType = VariableType.getNonReferenceType();
2512     NonReferenceType.removeLocalConst();
2513     SemaRef.Diag(VD->getLocStart(), diag::note_use_non_reference_type)
2514         << NonReferenceType << VD->getSourceRange();
2515   }
2516 }
2517 
2518 // Warns when the loop variable can be changed to a reference type to
2519 // prevent a copy.  For instance, if given "for (const Foo x : Range)" suggest
2520 // "for (const Foo &x : Range)" if this form does not make a copy.
DiagnoseForRangeConstVariableCopies(Sema & SemaRef,const VarDecl * VD)2521 static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef,
2522                                                 const VarDecl *VD) {
2523   const Expr *InitExpr = VD->getInit();
2524   if (!InitExpr)
2525     return;
2526 
2527   QualType VariableType = VD->getType();
2528 
2529   if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(InitExpr)) {
2530     if (!CE->getConstructor()->isCopyConstructor())
2531       return;
2532   } else if (const CastExpr *CE = dyn_cast<CastExpr>(InitExpr)) {
2533     if (CE->getCastKind() != CK_LValueToRValue)
2534       return;
2535   } else {
2536     return;
2537   }
2538 
2539   // TODO: Determine a maximum size that a POD type can be before a diagnostic
2540   // should be emitted.  Also, only ignore POD types with trivial copy
2541   // constructors.
2542   if (VariableType.isPODType(SemaRef.Context))
2543     return;
2544 
2545   // Suggest changing from a const variable to a const reference variable
2546   // if doing so will prevent a copy.
2547   SemaRef.Diag(VD->getLocation(), diag::warn_for_range_copy)
2548       << VD << VariableType << InitExpr->getType();
2549   SemaRef.Diag(VD->getLocStart(), diag::note_use_reference_type)
2550       << SemaRef.Context.getLValueReferenceType(VariableType)
2551       << VD->getSourceRange();
2552 }
2553 
2554 /// DiagnoseForRangeVariableCopies - Diagnose three cases and fixes for them.
2555 /// 1) for (const foo &x : foos) where foos only returns a copy.  Suggest
2556 ///    using "const foo x" to show that a copy is made
2557 /// 2) for (const bar &x : foos) where bar is a temporary intialized by bar.
2558 ///    Suggest either "const bar x" to keep the copying or "const foo& x" to
2559 ///    prevent the copy.
2560 /// 3) for (const foo x : foos) where x is constructed from a reference foo.
2561 ///    Suggest "const foo &x" to prevent the copy.
DiagnoseForRangeVariableCopies(Sema & SemaRef,const CXXForRangeStmt * ForStmt)2562 static void DiagnoseForRangeVariableCopies(Sema &SemaRef,
2563                                            const CXXForRangeStmt *ForStmt) {
2564   if (SemaRef.Diags.isIgnored(diag::warn_for_range_const_reference_copy,
2565                               ForStmt->getLocStart()) &&
2566       SemaRef.Diags.isIgnored(diag::warn_for_range_variable_always_copy,
2567                               ForStmt->getLocStart()) &&
2568       SemaRef.Diags.isIgnored(diag::warn_for_range_copy,
2569                               ForStmt->getLocStart())) {
2570     return;
2571   }
2572 
2573   const VarDecl *VD = ForStmt->getLoopVariable();
2574   if (!VD)
2575     return;
2576 
2577   QualType VariableType = VD->getType();
2578 
2579   if (VariableType->isIncompleteType())
2580     return;
2581 
2582   const Expr *InitExpr = VD->getInit();
2583   if (!InitExpr)
2584     return;
2585 
2586   if (VariableType->isReferenceType()) {
2587     DiagnoseForRangeReferenceVariableCopies(SemaRef, VD,
2588                                             ForStmt->getRangeInit()->getType());
2589   } else if (VariableType.isConstQualified()) {
2590     DiagnoseForRangeConstVariableCopies(SemaRef, VD);
2591   }
2592 }
2593 
2594 /// FinishCXXForRangeStmt - Attach the body to a C++0x for-range statement.
2595 /// This is a separate step from ActOnCXXForRangeStmt because analysis of the
2596 /// body cannot be performed until after the type of the range variable is
2597 /// determined.
FinishCXXForRangeStmt(Stmt * S,Stmt * B)2598 StmtResult Sema::FinishCXXForRangeStmt(Stmt *S, Stmt *B) {
2599   if (!S || !B)
2600     return StmtError();
2601 
2602   if (isa<ObjCForCollectionStmt>(S))
2603     return FinishObjCForCollectionStmt(S, B);
2604 
2605   CXXForRangeStmt *ForStmt = cast<CXXForRangeStmt>(S);
2606   ForStmt->setBody(B);
2607 
2608   DiagnoseEmptyStmtBody(ForStmt->getRParenLoc(), B,
2609                         diag::warn_empty_range_based_for_body);
2610 
2611   DiagnoseForRangeVariableCopies(*this, ForStmt);
2612 
2613   return S;
2614 }
2615 
ActOnGotoStmt(SourceLocation GotoLoc,SourceLocation LabelLoc,LabelDecl * TheDecl)2616 StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc,
2617                                SourceLocation LabelLoc,
2618                                LabelDecl *TheDecl) {
2619   getCurFunction()->setHasBranchIntoScope();
2620   TheDecl->markUsed(Context);
2621   return new (Context) GotoStmt(TheDecl, GotoLoc, LabelLoc);
2622 }
2623 
2624 StmtResult
ActOnIndirectGotoStmt(SourceLocation GotoLoc,SourceLocation StarLoc,Expr * E)2625 Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
2626                             Expr *E) {
2627   // Convert operand to void*
2628   if (!E->isTypeDependent()) {
2629     QualType ETy = E->getType();
2630     QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
2631     ExprResult ExprRes = E;
2632     AssignConvertType ConvTy =
2633       CheckSingleAssignmentConstraints(DestTy, ExprRes);
2634     if (ExprRes.isInvalid())
2635       return StmtError();
2636     E = ExprRes.get();
2637     if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
2638       return StmtError();
2639   }
2640 
2641   ExprResult ExprRes = ActOnFinishFullExpr(E);
2642   if (ExprRes.isInvalid())
2643     return StmtError();
2644   E = ExprRes.get();
2645 
2646   getCurFunction()->setHasIndirectGoto();
2647 
2648   return new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E);
2649 }
2650 
CheckJumpOutOfSEHFinally(Sema & S,SourceLocation Loc,const Scope & DestScope)2651 static void CheckJumpOutOfSEHFinally(Sema &S, SourceLocation Loc,
2652                                      const Scope &DestScope) {
2653   if (!S.CurrentSEHFinally.empty() &&
2654       DestScope.Contains(*S.CurrentSEHFinally.back())) {
2655     S.Diag(Loc, diag::warn_jump_out_of_seh_finally);
2656   }
2657 }
2658 
2659 StmtResult
ActOnContinueStmt(SourceLocation ContinueLoc,Scope * CurScope)2660 Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
2661   Scope *S = CurScope->getContinueParent();
2662   if (!S) {
2663     // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
2664     return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
2665   }
2666   CheckJumpOutOfSEHFinally(*this, ContinueLoc, *S);
2667 
2668   return new (Context) ContinueStmt(ContinueLoc);
2669 }
2670 
2671 StmtResult
ActOnBreakStmt(SourceLocation BreakLoc,Scope * CurScope)2672 Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
2673   Scope *S = CurScope->getBreakParent();
2674   if (!S) {
2675     // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
2676     return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
2677   }
2678   if (S->isOpenMPLoopScope())
2679     return StmtError(Diag(BreakLoc, diag::err_omp_loop_cannot_use_stmt)
2680                      << "break");
2681   CheckJumpOutOfSEHFinally(*this, BreakLoc, *S);
2682 
2683   return new (Context) BreakStmt(BreakLoc);
2684 }
2685 
2686 /// \brief Determine whether the given expression is a candidate for
2687 /// copy elision in either a return statement or a throw expression.
2688 ///
2689 /// \param ReturnType If we're determining the copy elision candidate for
2690 /// a return statement, this is the return type of the function. If we're
2691 /// determining the copy elision candidate for a throw expression, this will
2692 /// be a NULL type.
2693 ///
2694 /// \param E The expression being returned from the function or block, or
2695 /// being thrown.
2696 ///
2697 /// \param AllowParamOrMoveConstructible Whether we allow function parameters or
2698 /// id-expressions that could be moved out of the function to be considered NRVO
2699 /// candidates. C++ prohibits these for NRVO itself, but we re-use this logic to
2700 /// determine whether we should try to move as part of a return or throw (which
2701 /// does allow function parameters).
2702 ///
2703 /// \returns The NRVO candidate variable, if the return statement may use the
2704 /// NRVO, or NULL if there is no such candidate.
getCopyElisionCandidate(QualType ReturnType,Expr * E,bool AllowParamOrMoveConstructible)2705 VarDecl *Sema::getCopyElisionCandidate(QualType ReturnType, Expr *E,
2706                                        bool AllowParamOrMoveConstructible) {
2707   if (!getLangOpts().CPlusPlus)
2708     return nullptr;
2709 
2710   // - in a return statement in a function [where] ...
2711   // ... the expression is the name of a non-volatile automatic object ...
2712   DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E->IgnoreParens());
2713   if (!DR || DR->refersToEnclosingVariableOrCapture())
2714     return nullptr;
2715   VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
2716   if (!VD)
2717     return nullptr;
2718 
2719   if (isCopyElisionCandidate(ReturnType, VD, AllowParamOrMoveConstructible))
2720     return VD;
2721   return nullptr;
2722 }
2723 
isCopyElisionCandidate(QualType ReturnType,const VarDecl * VD,bool AllowParamOrMoveConstructible)2724 bool Sema::isCopyElisionCandidate(QualType ReturnType, const VarDecl *VD,
2725                                   bool AllowParamOrMoveConstructible) {
2726   QualType VDType = VD->getType();
2727   // - in a return statement in a function with ...
2728   // ... a class return type ...
2729   if (!ReturnType.isNull() && !ReturnType->isDependentType()) {
2730     if (!ReturnType->isRecordType())
2731       return false;
2732     // ... the same cv-unqualified type as the function return type ...
2733     // When considering moving this expression out, allow dissimilar types.
2734     if (!AllowParamOrMoveConstructible && !VDType->isDependentType() &&
2735         !Context.hasSameUnqualifiedType(ReturnType, VDType))
2736       return false;
2737   }
2738 
2739   // ...object (other than a function or catch-clause parameter)...
2740   if (VD->getKind() != Decl::Var &&
2741       !(AllowParamOrMoveConstructible && VD->getKind() == Decl::ParmVar))
2742     return false;
2743   if (VD->isExceptionVariable()) return false;
2744 
2745   // ...automatic...
2746   if (!VD->hasLocalStorage()) return false;
2747 
2748   if (AllowParamOrMoveConstructible)
2749     return true;
2750 
2751   // ...non-volatile...
2752   if (VD->getType().isVolatileQualified()) return false;
2753 
2754   // __block variables can't be allocated in a way that permits NRVO.
2755   if (VD->hasAttr<BlocksAttr>()) return false;
2756 
2757   // Variables with higher required alignment than their type's ABI
2758   // alignment cannot use NRVO.
2759   if (!VD->getType()->isDependentType() && VD->hasAttr<AlignedAttr>() &&
2760       Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VD->getType()))
2761     return false;
2762 
2763   return true;
2764 }
2765 
2766 /// \brief Perform the initialization of a potentially-movable value, which
2767 /// is the result of return value.
2768 ///
2769 /// This routine implements C++14 [class.copy]p32, which attempts to treat
2770 /// returned lvalues as rvalues in certain cases (to prefer move construction),
2771 /// then falls back to treating them as lvalues if that failed.
2772 ExprResult
PerformMoveOrCopyInitialization(const InitializedEntity & Entity,const VarDecl * NRVOCandidate,QualType ResultType,Expr * Value,bool AllowNRVO)2773 Sema::PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
2774                                       const VarDecl *NRVOCandidate,
2775                                       QualType ResultType,
2776                                       Expr *Value,
2777                                       bool AllowNRVO) {
2778   // C++14 [class.copy]p32:
2779   // When the criteria for elision of a copy/move operation are met, but not for
2780   // an exception-declaration, and the object to be copied is designated by an
2781   // lvalue, or when the expression in a return statement is a (possibly
2782   // parenthesized) id-expression that names an object with automatic storage
2783   // duration declared in the body or parameter-declaration-clause of the
2784   // innermost enclosing function or lambda-expression, overload resolution to
2785   // select the constructor for the copy is first performed as if the object
2786   // were designated by an rvalue.
2787   ExprResult Res = ExprError();
2788 
2789   if (AllowNRVO && !NRVOCandidate)
2790     NRVOCandidate = getCopyElisionCandidate(ResultType, Value, true);
2791 
2792   if (AllowNRVO && NRVOCandidate) {
2793     ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(),
2794                               CK_NoOp, Value, VK_XValue);
2795 
2796     Expr *InitExpr = &AsRvalue;
2797 
2798     InitializationKind Kind = InitializationKind::CreateCopy(
2799         Value->getLocStart(), Value->getLocStart());
2800 
2801     InitializationSequence Seq(*this, Entity, Kind, InitExpr);
2802     if (Seq) {
2803       for (const InitializationSequence::Step &Step : Seq.steps()) {
2804         if (!(Step.Kind ==
2805                   InitializationSequence::SK_ConstructorInitialization ||
2806               (Step.Kind == InitializationSequence::SK_UserConversion &&
2807                isa<CXXConstructorDecl>(Step.Function.Function))))
2808           continue;
2809 
2810         CXXConstructorDecl *Constructor =
2811             cast<CXXConstructorDecl>(Step.Function.Function);
2812 
2813         const RValueReferenceType *RRefType
2814           = Constructor->getParamDecl(0)->getType()
2815                                                  ->getAs<RValueReferenceType>();
2816 
2817         // [...] If the first overload resolution fails or was not performed, or
2818         // if the type of the first parameter of the selected constructor is not
2819         // an rvalue reference to the object’s type (possibly cv-qualified),
2820         // overload resolution is performed again, considering the object as an
2821         // lvalue.
2822         if (!RRefType ||
2823             !Context.hasSameUnqualifiedType(RRefType->getPointeeType(),
2824                                             NRVOCandidate->getType()))
2825           break;
2826 
2827         // Promote "AsRvalue" to the heap, since we now need this
2828         // expression node to persist.
2829         Value = ImplicitCastExpr::Create(Context, Value->getType(), CK_NoOp,
2830                                          Value, nullptr, VK_XValue);
2831 
2832         // Complete type-checking the initialization of the return type
2833         // using the constructor we found.
2834         Res = Seq.Perform(*this, Entity, Kind, Value);
2835       }
2836     }
2837   }
2838 
2839   // Either we didn't meet the criteria for treating an lvalue as an rvalue,
2840   // above, or overload resolution failed. Either way, we need to try
2841   // (again) now with the return value expression as written.
2842   if (Res.isInvalid())
2843     Res = PerformCopyInitialization(Entity, SourceLocation(), Value);
2844 
2845   return Res;
2846 }
2847 
2848 /// \brief Determine whether the declared return type of the specified function
2849 /// contains 'auto'.
hasDeducedReturnType(FunctionDecl * FD)2850 static bool hasDeducedReturnType(FunctionDecl *FD) {
2851   const FunctionProtoType *FPT =
2852       FD->getTypeSourceInfo()->getType()->castAs<FunctionProtoType>();
2853   return FPT->getReturnType()->isUndeducedType();
2854 }
2855 
2856 /// ActOnCapScopeReturnStmt - Utility routine to type-check return statements
2857 /// for capturing scopes.
2858 ///
2859 StmtResult
ActOnCapScopeReturnStmt(SourceLocation ReturnLoc,Expr * RetValExp)2860 Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
2861   // If this is the first return we've seen, infer the return type.
2862   // [expr.prim.lambda]p4 in C++11; block literals follow the same rules.
2863   CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
2864   QualType FnRetType = CurCap->ReturnType;
2865   LambdaScopeInfo *CurLambda = dyn_cast<LambdaScopeInfo>(CurCap);
2866   bool HasDeducedReturnType =
2867       CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
2868 
2869   if (ExprEvalContexts.back().Context == DiscardedStatement &&
2870       (HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
2871     if (RetValExp) {
2872       ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
2873       if (ER.isInvalid())
2874         return StmtError();
2875       RetValExp = ER.get();
2876     }
2877     return new (Context) ReturnStmt(ReturnLoc, RetValExp, nullptr);
2878   }
2879 
2880   if (HasDeducedReturnType) {
2881     // In C++1y, the return type may involve 'auto'.
2882     // FIXME: Blocks might have a return type of 'auto' explicitly specified.
2883     FunctionDecl *FD = CurLambda->CallOperator;
2884     if (CurCap->ReturnType.isNull())
2885       CurCap->ReturnType = FD->getReturnType();
2886 
2887     AutoType *AT = CurCap->ReturnType->getContainedAutoType();
2888     assert(AT && "lost auto type from lambda return type");
2889     if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
2890       FD->setInvalidDecl();
2891       return StmtError();
2892     }
2893     CurCap->ReturnType = FnRetType = FD->getReturnType();
2894   } else if (CurCap->HasImplicitReturnType) {
2895     // For blocks/lambdas with implicit return types, we check each return
2896     // statement individually, and deduce the common return type when the block
2897     // or lambda is completed.
2898     // FIXME: Fold this into the 'auto' codepath above.
2899     if (RetValExp && !isa<InitListExpr>(RetValExp)) {
2900       ExprResult Result = DefaultFunctionArrayLvalueConversion(RetValExp);
2901       if (Result.isInvalid())
2902         return StmtError();
2903       RetValExp = Result.get();
2904 
2905       // DR1048: even prior to C++14, we should use the 'auto' deduction rules
2906       // when deducing a return type for a lambda-expression (or by extension
2907       // for a block). These rules differ from the stated C++11 rules only in
2908       // that they remove top-level cv-qualifiers.
2909       if (!CurContext->isDependentContext())
2910         FnRetType = RetValExp->getType().getUnqualifiedType();
2911       else
2912         FnRetType = CurCap->ReturnType = Context.DependentTy;
2913     } else {
2914       if (RetValExp) {
2915         // C++11 [expr.lambda.prim]p4 bans inferring the result from an
2916         // initializer list, because it is not an expression (even
2917         // though we represent it as one). We still deduce 'void'.
2918         Diag(ReturnLoc, diag::err_lambda_return_init_list)
2919           << RetValExp->getSourceRange();
2920       }
2921 
2922       FnRetType = Context.VoidTy;
2923     }
2924 
2925     // Although we'll properly infer the type of the block once it's completed,
2926     // make sure we provide a return type now for better error recovery.
2927     if (CurCap->ReturnType.isNull())
2928       CurCap->ReturnType = FnRetType;
2929   }
2930   assert(!FnRetType.isNull());
2931 
2932   if (BlockScopeInfo *CurBlock = dyn_cast<BlockScopeInfo>(CurCap)) {
2933     if (CurBlock->FunctionType->getAs<FunctionType>()->getNoReturnAttr()) {
2934       Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr);
2935       return StmtError();
2936     }
2937   } else if (CapturedRegionScopeInfo *CurRegion =
2938                  dyn_cast<CapturedRegionScopeInfo>(CurCap)) {
2939     Diag(ReturnLoc, diag::err_return_in_captured_stmt) << CurRegion->getRegionName();
2940     return StmtError();
2941   } else {
2942     assert(CurLambda && "unknown kind of captured scope");
2943     if (CurLambda->CallOperator->getType()->getAs<FunctionType>()
2944             ->getNoReturnAttr()) {
2945       Diag(ReturnLoc, diag::err_noreturn_lambda_has_return_expr);
2946       return StmtError();
2947     }
2948   }
2949 
2950   // Otherwise, verify that this result type matches the previous one.  We are
2951   // pickier with blocks than for normal functions because we don't have GCC
2952   // compatibility to worry about here.
2953   const VarDecl *NRVOCandidate = nullptr;
2954   if (FnRetType->isDependentType()) {
2955     // Delay processing for now.  TODO: there are lots of dependent
2956     // types we can conclusively prove aren't void.
2957   } else if (FnRetType->isVoidType()) {
2958     if (RetValExp && !isa<InitListExpr>(RetValExp) &&
2959         !(getLangOpts().CPlusPlus &&
2960           (RetValExp->isTypeDependent() ||
2961            RetValExp->getType()->isVoidType()))) {
2962       if (!getLangOpts().CPlusPlus &&
2963           RetValExp->getType()->isVoidType())
2964         Diag(ReturnLoc, diag::ext_return_has_void_expr) << "literal" << 2;
2965       else {
2966         Diag(ReturnLoc, diag::err_return_block_has_expr);
2967         RetValExp = nullptr;
2968       }
2969     }
2970   } else if (!RetValExp) {
2971     return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
2972   } else if (!RetValExp->isTypeDependent()) {
2973     // we have a non-void block with an expression, continue checking
2974 
2975     // C99 6.8.6.4p3(136): The return statement is not an assignment. The
2976     // overlap restriction of subclause 6.5.16.1 does not apply to the case of
2977     // function return.
2978 
2979     // In C++ the return statement is handled via a copy initialization.
2980     // the C version of which boils down to CheckSingleAssignmentConstraints.
2981     NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
2982     InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
2983                                                                    FnRetType,
2984                                                       NRVOCandidate != nullptr);
2985     ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
2986                                                      FnRetType, RetValExp);
2987     if (Res.isInvalid()) {
2988       // FIXME: Cleanup temporaries here, anyway?
2989       return StmtError();
2990     }
2991     RetValExp = Res.get();
2992     CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc);
2993   } else {
2994     NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
2995   }
2996 
2997   if (RetValExp) {
2998     ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
2999     if (ER.isInvalid())
3000       return StmtError();
3001     RetValExp = ER.get();
3002   }
3003   ReturnStmt *Result = new (Context) ReturnStmt(ReturnLoc, RetValExp,
3004                                                 NRVOCandidate);
3005 
3006   // If we need to check for the named return value optimization,
3007   // or if we need to infer the return type,
3008   // save the return statement in our scope for later processing.
3009   if (CurCap->HasImplicitReturnType || NRVOCandidate)
3010     FunctionScopes.back()->Returns.push_back(Result);
3011 
3012   if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3013     FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3014 
3015   return Result;
3016 }
3017 
3018 namespace {
3019 /// \brief Marks all typedefs in all local classes in a type referenced.
3020 ///
3021 /// In a function like
3022 /// auto f() {
3023 ///   struct S { typedef int a; };
3024 ///   return S();
3025 /// }
3026 ///
3027 /// the local type escapes and could be referenced in some TUs but not in
3028 /// others. Pretend that all local typedefs are always referenced, to not warn
3029 /// on this. This isn't necessary if f has internal linkage, or the typedef
3030 /// is private.
3031 class LocalTypedefNameReferencer
3032     : public RecursiveASTVisitor<LocalTypedefNameReferencer> {
3033 public:
LocalTypedefNameReferencer(Sema & S)3034   LocalTypedefNameReferencer(Sema &S) : S(S) {}
3035   bool VisitRecordType(const RecordType *RT);
3036 private:
3037   Sema &S;
3038 };
VisitRecordType(const RecordType * RT)3039 bool LocalTypedefNameReferencer::VisitRecordType(const RecordType *RT) {
3040   auto *R = dyn_cast<CXXRecordDecl>(RT->getDecl());
3041   if (!R || !R->isLocalClass() || !R->isLocalClass()->isExternallyVisible() ||
3042       R->isDependentType())
3043     return true;
3044   for (auto *TmpD : R->decls())
3045     if (auto *T = dyn_cast<TypedefNameDecl>(TmpD))
3046       if (T->getAccess() != AS_private || R->hasFriends())
3047         S.MarkAnyDeclReferenced(T->getLocation(), T, /*OdrUse=*/false);
3048   return true;
3049 }
3050 }
3051 
getReturnTypeLoc(FunctionDecl * FD) const3052 TypeLoc Sema::getReturnTypeLoc(FunctionDecl *FD) const {
3053   TypeLoc TL = FD->getTypeSourceInfo()->getTypeLoc().IgnoreParens();
3054   while (auto ATL = TL.getAs<AttributedTypeLoc>())
3055     TL = ATL.getModifiedLoc().IgnoreParens();
3056   return TL.castAs<FunctionProtoTypeLoc>().getReturnLoc();
3057 }
3058 
3059 /// Deduce the return type for a function from a returned expression, per
3060 /// C++1y [dcl.spec.auto]p6.
DeduceFunctionTypeFromReturnExpr(FunctionDecl * FD,SourceLocation ReturnLoc,Expr * & RetExpr,AutoType * AT)3061 bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
3062                                             SourceLocation ReturnLoc,
3063                                             Expr *&RetExpr,
3064                                             AutoType *AT) {
3065   TypeLoc OrigResultType = getReturnTypeLoc(FD);
3066   QualType Deduced;
3067 
3068   if (RetExpr && isa<InitListExpr>(RetExpr)) {
3069     //  If the deduction is for a return statement and the initializer is
3070     //  a braced-init-list, the program is ill-formed.
3071     Diag(RetExpr->getExprLoc(),
3072          getCurLambda() ? diag::err_lambda_return_init_list
3073                         : diag::err_auto_fn_return_init_list)
3074         << RetExpr->getSourceRange();
3075     return true;
3076   }
3077 
3078   if (FD->isDependentContext()) {
3079     // C++1y [dcl.spec.auto]p12:
3080     //   Return type deduction [...] occurs when the definition is
3081     //   instantiated even if the function body contains a return
3082     //   statement with a non-type-dependent operand.
3083     assert(AT->isDeduced() && "should have deduced to dependent type");
3084     return false;
3085   }
3086 
3087   if (RetExpr) {
3088     //  Otherwise, [...] deduce a value for U using the rules of template
3089     //  argument deduction.
3090     DeduceAutoResult DAR = DeduceAutoType(OrigResultType, RetExpr, Deduced);
3091 
3092     if (DAR == DAR_Failed && !FD->isInvalidDecl())
3093       Diag(RetExpr->getExprLoc(), diag::err_auto_fn_deduction_failure)
3094         << OrigResultType.getType() << RetExpr->getType();
3095 
3096     if (DAR != DAR_Succeeded)
3097       return true;
3098 
3099     // If a local type is part of the returned type, mark its fields as
3100     // referenced.
3101     LocalTypedefNameReferencer Referencer(*this);
3102     Referencer.TraverseType(RetExpr->getType());
3103   } else {
3104     //  In the case of a return with no operand, the initializer is considered
3105     //  to be void().
3106     //
3107     // Deduction here can only succeed if the return type is exactly 'cv auto'
3108     // or 'decltype(auto)', so just check for that case directly.
3109     if (!OrigResultType.getType()->getAs<AutoType>()) {
3110       Diag(ReturnLoc, diag::err_auto_fn_return_void_but_not_auto)
3111         << OrigResultType.getType();
3112       return true;
3113     }
3114     // We always deduce U = void in this case.
3115     Deduced = SubstAutoType(OrigResultType.getType(), Context.VoidTy);
3116     if (Deduced.isNull())
3117       return true;
3118   }
3119 
3120   //  If a function with a declared return type that contains a placeholder type
3121   //  has multiple return statements, the return type is deduced for each return
3122   //  statement. [...] if the type deduced is not the same in each deduction,
3123   //  the program is ill-formed.
3124   QualType DeducedT = AT->getDeducedType();
3125   if (!DeducedT.isNull() && !FD->isInvalidDecl()) {
3126     AutoType *NewAT = Deduced->getContainedAutoType();
3127     // It is possible that NewAT->getDeducedType() is null. When that happens,
3128     // we should not crash, instead we ignore this deduction.
3129     if (NewAT->getDeducedType().isNull())
3130       return false;
3131 
3132     CanQualType OldDeducedType = Context.getCanonicalFunctionResultType(
3133                                    DeducedT);
3134     CanQualType NewDeducedType = Context.getCanonicalFunctionResultType(
3135                                    NewAT->getDeducedType());
3136     if (!FD->isDependentContext() && OldDeducedType != NewDeducedType) {
3137       const LambdaScopeInfo *LambdaSI = getCurLambda();
3138       if (LambdaSI && LambdaSI->HasImplicitReturnType) {
3139         Diag(ReturnLoc, diag::err_typecheck_missing_return_type_incompatible)
3140           << NewAT->getDeducedType() << DeducedT
3141           << true /*IsLambda*/;
3142       } else {
3143         Diag(ReturnLoc, diag::err_auto_fn_different_deductions)
3144           << (AT->isDecltypeAuto() ? 1 : 0)
3145           << NewAT->getDeducedType() << DeducedT;
3146       }
3147       return true;
3148     }
3149   } else if (!FD->isInvalidDecl()) {
3150     // Update all declarations of the function to have the deduced return type.
3151     Context.adjustDeducedFunctionResultType(FD, Deduced);
3152   }
3153 
3154   return false;
3155 }
3156 
3157 StmtResult
ActOnReturnStmt(SourceLocation ReturnLoc,Expr * RetValExp,Scope * CurScope)3158 Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
3159                       Scope *CurScope) {
3160   StmtResult R = BuildReturnStmt(ReturnLoc, RetValExp);
3161   if (R.isInvalid() || ExprEvalContexts.back().Context == DiscardedStatement)
3162     return R;
3163 
3164   if (VarDecl *VD =
3165       const_cast<VarDecl*>(cast<ReturnStmt>(R.get())->getNRVOCandidate())) {
3166     CurScope->addNRVOCandidate(VD);
3167   } else {
3168     CurScope->setNoNRVO();
3169   }
3170 
3171   CheckJumpOutOfSEHFinally(*this, ReturnLoc, *CurScope->getFnParent());
3172 
3173   return R;
3174 }
3175 
BuildReturnStmt(SourceLocation ReturnLoc,Expr * RetValExp)3176 StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
3177   // Check for unexpanded parameter packs.
3178   if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp))
3179     return StmtError();
3180 
3181   if (isa<CapturingScopeInfo>(getCurFunction()))
3182     return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp);
3183 
3184   QualType FnRetType;
3185   QualType RelatedRetType;
3186   const AttrVec *Attrs = nullptr;
3187   bool isObjCMethod = false;
3188 
3189   if (const FunctionDecl *FD = getCurFunctionDecl()) {
3190     FnRetType = FD->getReturnType();
3191     if (FD->hasAttrs())
3192       Attrs = &FD->getAttrs();
3193     if (FD->isNoReturn())
3194       Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
3195         << FD->getDeclName();
3196   } else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
3197     FnRetType = MD->getReturnType();
3198     isObjCMethod = true;
3199     if (MD->hasAttrs())
3200       Attrs = &MD->getAttrs();
3201     if (MD->hasRelatedResultType() && MD->getClassInterface()) {
3202       // In the implementation of a method with a related return type, the
3203       // type used to type-check the validity of return statements within the
3204       // method body is a pointer to the type of the class being implemented.
3205       RelatedRetType = Context.getObjCInterfaceType(MD->getClassInterface());
3206       RelatedRetType = Context.getObjCObjectPointerType(RelatedRetType);
3207     }
3208   } else // If we don't have a function/method context, bail.
3209     return StmtError();
3210 
3211   // C++1z: discarded return statements are not considered when deducing a
3212   // return type.
3213   if (ExprEvalContexts.back().Context == DiscardedStatement &&
3214       FnRetType->getContainedAutoType()) {
3215     if (RetValExp) {
3216       ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
3217       if (ER.isInvalid())
3218         return StmtError();
3219       RetValExp = ER.get();
3220     }
3221     return new (Context) ReturnStmt(ReturnLoc, RetValExp, nullptr);
3222   }
3223 
3224   // FIXME: Add a flag to the ScopeInfo to indicate whether we're performing
3225   // deduction.
3226   if (getLangOpts().CPlusPlus14) {
3227     if (AutoType *AT = FnRetType->getContainedAutoType()) {
3228       FunctionDecl *FD = cast<FunctionDecl>(CurContext);
3229       if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
3230         FD->setInvalidDecl();
3231         return StmtError();
3232       } else {
3233         FnRetType = FD->getReturnType();
3234       }
3235     }
3236   }
3237 
3238   bool HasDependentReturnType = FnRetType->isDependentType();
3239 
3240   ReturnStmt *Result = nullptr;
3241   if (FnRetType->isVoidType()) {
3242     if (RetValExp) {
3243       if (isa<InitListExpr>(RetValExp)) {
3244         // We simply never allow init lists as the return value of void
3245         // functions. This is compatible because this was never allowed before,
3246         // so there's no legacy code to deal with.
3247         NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3248         int FunctionKind = 0;
3249         if (isa<ObjCMethodDecl>(CurDecl))
3250           FunctionKind = 1;
3251         else if (isa<CXXConstructorDecl>(CurDecl))
3252           FunctionKind = 2;
3253         else if (isa<CXXDestructorDecl>(CurDecl))
3254           FunctionKind = 3;
3255 
3256         Diag(ReturnLoc, diag::err_return_init_list)
3257           << CurDecl->getDeclName() << FunctionKind
3258           << RetValExp->getSourceRange();
3259 
3260         // Drop the expression.
3261         RetValExp = nullptr;
3262       } else if (!RetValExp->isTypeDependent()) {
3263         // C99 6.8.6.4p1 (ext_ since GCC warns)
3264         unsigned D = diag::ext_return_has_expr;
3265         if (RetValExp->getType()->isVoidType()) {
3266           NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3267           if (isa<CXXConstructorDecl>(CurDecl) ||
3268               isa<CXXDestructorDecl>(CurDecl))
3269             D = diag::err_ctor_dtor_returns_void;
3270           else
3271             D = diag::ext_return_has_void_expr;
3272         }
3273         else {
3274           ExprResult Result = RetValExp;
3275           Result = IgnoredValueConversions(Result.get());
3276           if (Result.isInvalid())
3277             return StmtError();
3278           RetValExp = Result.get();
3279           RetValExp = ImpCastExprToType(RetValExp,
3280                                         Context.VoidTy, CK_ToVoid).get();
3281         }
3282         // return of void in constructor/destructor is illegal in C++.
3283         if (D == diag::err_ctor_dtor_returns_void) {
3284           NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3285           Diag(ReturnLoc, D)
3286             << CurDecl->getDeclName() << isa<CXXDestructorDecl>(CurDecl)
3287             << RetValExp->getSourceRange();
3288         }
3289         // return (some void expression); is legal in C++.
3290         else if (D != diag::ext_return_has_void_expr ||
3291                  !getLangOpts().CPlusPlus) {
3292           NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
3293 
3294           int FunctionKind = 0;
3295           if (isa<ObjCMethodDecl>(CurDecl))
3296             FunctionKind = 1;
3297           else if (isa<CXXConstructorDecl>(CurDecl))
3298             FunctionKind = 2;
3299           else if (isa<CXXDestructorDecl>(CurDecl))
3300             FunctionKind = 3;
3301 
3302           Diag(ReturnLoc, D)
3303             << CurDecl->getDeclName() << FunctionKind
3304             << RetValExp->getSourceRange();
3305         }
3306       }
3307 
3308       if (RetValExp) {
3309         ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
3310         if (ER.isInvalid())
3311           return StmtError();
3312         RetValExp = ER.get();
3313       }
3314     }
3315 
3316     Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, nullptr);
3317   } else if (!RetValExp && !HasDependentReturnType) {
3318     FunctionDecl *FD = getCurFunctionDecl();
3319 
3320     unsigned DiagID;
3321     if (getLangOpts().CPlusPlus11 && FD && FD->isConstexpr()) {
3322       // C++11 [stmt.return]p2
3323       DiagID = diag::err_constexpr_return_missing_expr;
3324       FD->setInvalidDecl();
3325     } else if (getLangOpts().C99) {
3326       // C99 6.8.6.4p1 (ext_ since GCC warns)
3327       DiagID = diag::ext_return_missing_expr;
3328     } else {
3329       // C90 6.6.6.4p4
3330       DiagID = diag::warn_return_missing_expr;
3331     }
3332 
3333     if (FD)
3334       Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
3335     else
3336       Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
3337 
3338     Result = new (Context) ReturnStmt(ReturnLoc);
3339   } else {
3340     assert(RetValExp || HasDependentReturnType);
3341     const VarDecl *NRVOCandidate = nullptr;
3342 
3343     QualType RetType = RelatedRetType.isNull() ? FnRetType : RelatedRetType;
3344 
3345     // C99 6.8.6.4p3(136): The return statement is not an assignment. The
3346     // overlap restriction of subclause 6.5.16.1 does not apply to the case of
3347     // function return.
3348 
3349     // In C++ the return statement is handled via a copy initialization,
3350     // the C version of which boils down to CheckSingleAssignmentConstraints.
3351     if (RetValExp)
3352       NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, false);
3353     if (!HasDependentReturnType && !RetValExp->isTypeDependent()) {
3354       // we have a non-void function with an expression, continue checking
3355       InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
3356                                                                      RetType,
3357                                                       NRVOCandidate != nullptr);
3358       ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
3359                                                        RetType, RetValExp);
3360       if (Res.isInvalid()) {
3361         // FIXME: Clean up temporaries here anyway?
3362         return StmtError();
3363       }
3364       RetValExp = Res.getAs<Expr>();
3365 
3366       // If we have a related result type, we need to implicitly
3367       // convert back to the formal result type.  We can't pretend to
3368       // initialize the result again --- we might end double-retaining
3369       // --- so instead we initialize a notional temporary.
3370       if (!RelatedRetType.isNull()) {
3371         Entity = InitializedEntity::InitializeRelatedResult(getCurMethodDecl(),
3372                                                             FnRetType);
3373         Res = PerformCopyInitialization(Entity, ReturnLoc, RetValExp);
3374         if (Res.isInvalid()) {
3375           // FIXME: Clean up temporaries here anyway?
3376           return StmtError();
3377         }
3378         RetValExp = Res.getAs<Expr>();
3379       }
3380 
3381       CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc, isObjCMethod, Attrs,
3382                          getCurFunctionDecl());
3383     }
3384 
3385     if (RetValExp) {
3386       ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
3387       if (ER.isInvalid())
3388         return StmtError();
3389       RetValExp = ER.get();
3390     }
3391     Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, NRVOCandidate);
3392   }
3393 
3394   // If we need to check for the named return value optimization, save the
3395   // return statement in our scope for later processing.
3396   if (Result->getNRVOCandidate())
3397     FunctionScopes.back()->Returns.push_back(Result);
3398 
3399   if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3400     FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3401 
3402   return Result;
3403 }
3404 
3405 StmtResult
ActOnObjCAtCatchStmt(SourceLocation AtLoc,SourceLocation RParen,Decl * Parm,Stmt * Body)3406 Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
3407                            SourceLocation RParen, Decl *Parm,
3408                            Stmt *Body) {
3409   VarDecl *Var = cast_or_null<VarDecl>(Parm);
3410   if (Var && Var->isInvalidDecl())
3411     return StmtError();
3412 
3413   return new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body);
3414 }
3415 
3416 StmtResult
ActOnObjCAtFinallyStmt(SourceLocation AtLoc,Stmt * Body)3417 Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
3418   return new (Context) ObjCAtFinallyStmt(AtLoc, Body);
3419 }
3420 
3421 StmtResult
ActOnObjCAtTryStmt(SourceLocation AtLoc,Stmt * Try,MultiStmtArg CatchStmts,Stmt * Finally)3422 Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
3423                          MultiStmtArg CatchStmts, Stmt *Finally) {
3424   if (!getLangOpts().ObjCExceptions)
3425     Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@try";
3426 
3427   getCurFunction()->setHasBranchProtectedScope();
3428   unsigned NumCatchStmts = CatchStmts.size();
3429   return ObjCAtTryStmt::Create(Context, AtLoc, Try, CatchStmts.data(),
3430                                NumCatchStmts, Finally);
3431 }
3432 
BuildObjCAtThrowStmt(SourceLocation AtLoc,Expr * Throw)3433 StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) {
3434   if (Throw) {
3435     ExprResult Result = DefaultLvalueConversion(Throw);
3436     if (Result.isInvalid())
3437       return StmtError();
3438 
3439     Result = ActOnFinishFullExpr(Result.get());
3440     if (Result.isInvalid())
3441       return StmtError();
3442     Throw = Result.get();
3443 
3444     QualType ThrowType = Throw->getType();
3445     // Make sure the expression type is an ObjC pointer or "void *".
3446     if (!ThrowType->isDependentType() &&
3447         !ThrowType->isObjCObjectPointerType()) {
3448       const PointerType *PT = ThrowType->getAs<PointerType>();
3449       if (!PT || !PT->getPointeeType()->isVoidType())
3450         return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
3451                          << Throw->getType() << Throw->getSourceRange());
3452     }
3453   }
3454 
3455   return new (Context) ObjCAtThrowStmt(AtLoc, Throw);
3456 }
3457 
3458 StmtResult
ActOnObjCAtThrowStmt(SourceLocation AtLoc,Expr * Throw,Scope * CurScope)3459 Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
3460                            Scope *CurScope) {
3461   if (!getLangOpts().ObjCExceptions)
3462     Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@throw";
3463 
3464   if (!Throw) {
3465     // @throw without an expression designates a rethrow (which must occur
3466     // in the context of an @catch clause).
3467     Scope *AtCatchParent = CurScope;
3468     while (AtCatchParent && !AtCatchParent->isAtCatchScope())
3469       AtCatchParent = AtCatchParent->getParent();
3470     if (!AtCatchParent)
3471       return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
3472   }
3473   return BuildObjCAtThrowStmt(AtLoc, Throw);
3474 }
3475 
3476 ExprResult
ActOnObjCAtSynchronizedOperand(SourceLocation atLoc,Expr * operand)3477 Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
3478   ExprResult result = DefaultLvalueConversion(operand);
3479   if (result.isInvalid())
3480     return ExprError();
3481   operand = result.get();
3482 
3483   // Make sure the expression type is an ObjC pointer or "void *".
3484   QualType type = operand->getType();
3485   if (!type->isDependentType() &&
3486       !type->isObjCObjectPointerType()) {
3487     const PointerType *pointerType = type->getAs<PointerType>();
3488     if (!pointerType || !pointerType->getPointeeType()->isVoidType()) {
3489       if (getLangOpts().CPlusPlus) {
3490         if (RequireCompleteType(atLoc, type,
3491                                 diag::err_incomplete_receiver_type))
3492           return Diag(atLoc, diag::error_objc_synchronized_expects_object)
3493                    << type << operand->getSourceRange();
3494 
3495         ExprResult result = PerformContextuallyConvertToObjCPointer(operand);
3496         if (!result.isUsable())
3497           return Diag(atLoc, diag::error_objc_synchronized_expects_object)
3498                    << type << operand->getSourceRange();
3499 
3500         operand = result.get();
3501       } else {
3502           return Diag(atLoc, diag::error_objc_synchronized_expects_object)
3503                    << type << operand->getSourceRange();
3504       }
3505     }
3506   }
3507 
3508   // The operand to @synchronized is a full-expression.
3509   return ActOnFinishFullExpr(operand);
3510 }
3511 
3512 StmtResult
ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc,Expr * SyncExpr,Stmt * SyncBody)3513 Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
3514                                   Stmt *SyncBody) {
3515   // We can't jump into or indirect-jump out of a @synchronized block.
3516   getCurFunction()->setHasBranchProtectedScope();
3517   return new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody);
3518 }
3519 
3520 /// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
3521 /// and creates a proper catch handler from them.
3522 StmtResult
ActOnCXXCatchBlock(SourceLocation CatchLoc,Decl * ExDecl,Stmt * HandlerBlock)3523 Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
3524                          Stmt *HandlerBlock) {
3525   // There's nothing to test that ActOnExceptionDecl didn't already test.
3526   return new (Context)
3527       CXXCatchStmt(CatchLoc, cast_or_null<VarDecl>(ExDecl), HandlerBlock);
3528 }
3529 
3530 StmtResult
ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc,Stmt * Body)3531 Sema::ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body) {
3532   getCurFunction()->setHasBranchProtectedScope();
3533   return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body);
3534 }
3535 
3536 namespace {
3537 class CatchHandlerType {
3538   QualType QT;
3539   unsigned IsPointer : 1;
3540 
3541   // This is a special constructor to be used only with DenseMapInfo's
3542   // getEmptyKey() and getTombstoneKey() functions.
3543   friend struct llvm::DenseMapInfo<CatchHandlerType>;
3544   enum Unique { ForDenseMap };
CatchHandlerType(QualType QT,Unique)3545   CatchHandlerType(QualType QT, Unique) : QT(QT), IsPointer(false) {}
3546 
3547 public:
3548   /// Used when creating a CatchHandlerType from a handler type; will determine
3549   /// whether the type is a pointer or reference and will strip off the top
3550   /// level pointer and cv-qualifiers.
CatchHandlerType(QualType Q)3551   CatchHandlerType(QualType Q) : QT(Q), IsPointer(false) {
3552     if (QT->isPointerType())
3553       IsPointer = true;
3554 
3555     if (IsPointer || QT->isReferenceType())
3556       QT = QT->getPointeeType();
3557     QT = QT.getUnqualifiedType();
3558   }
3559 
3560   /// Used when creating a CatchHandlerType from a base class type; pretends the
3561   /// type passed in had the pointer qualifier, does not need to get an
3562   /// unqualified type.
CatchHandlerType(QualType QT,bool IsPointer)3563   CatchHandlerType(QualType QT, bool IsPointer)
3564       : QT(QT), IsPointer(IsPointer) {}
3565 
underlying() const3566   QualType underlying() const { return QT; }
isPointer() const3567   bool isPointer() const { return IsPointer; }
3568 
operator ==(const CatchHandlerType & LHS,const CatchHandlerType & RHS)3569   friend bool operator==(const CatchHandlerType &LHS,
3570                          const CatchHandlerType &RHS) {
3571     // If the pointer qualification does not match, we can return early.
3572     if (LHS.IsPointer != RHS.IsPointer)
3573       return false;
3574     // Otherwise, check the underlying type without cv-qualifiers.
3575     return LHS.QT == RHS.QT;
3576   }
3577 };
3578 } // namespace
3579 
3580 namespace llvm {
3581 template <> struct DenseMapInfo<CatchHandlerType> {
getEmptyKeyllvm::DenseMapInfo3582   static CatchHandlerType getEmptyKey() {
3583     return CatchHandlerType(DenseMapInfo<QualType>::getEmptyKey(),
3584                        CatchHandlerType::ForDenseMap);
3585   }
3586 
getTombstoneKeyllvm::DenseMapInfo3587   static CatchHandlerType getTombstoneKey() {
3588     return CatchHandlerType(DenseMapInfo<QualType>::getTombstoneKey(),
3589                        CatchHandlerType::ForDenseMap);
3590   }
3591 
getHashValuellvm::DenseMapInfo3592   static unsigned getHashValue(const CatchHandlerType &Base) {
3593     return DenseMapInfo<QualType>::getHashValue(Base.underlying());
3594   }
3595 
isEqualllvm::DenseMapInfo3596   static bool isEqual(const CatchHandlerType &LHS,
3597                       const CatchHandlerType &RHS) {
3598     return LHS == RHS;
3599   }
3600 };
3601 }
3602 
3603 namespace {
3604 class CatchTypePublicBases {
3605   ASTContext &Ctx;
3606   const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &TypesToCheck;
3607   const bool CheckAgainstPointer;
3608 
3609   CXXCatchStmt *FoundHandler;
3610   CanQualType FoundHandlerType;
3611 
3612 public:
CatchTypePublicBases(ASTContext & Ctx,const llvm::DenseMap<CatchHandlerType,CXXCatchStmt * > & T,bool C)3613   CatchTypePublicBases(
3614       ASTContext &Ctx,
3615       const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &T, bool C)
3616       : Ctx(Ctx), TypesToCheck(T), CheckAgainstPointer(C),
3617         FoundHandler(nullptr) {}
3618 
getFoundHandler() const3619   CXXCatchStmt *getFoundHandler() const { return FoundHandler; }
getFoundHandlerType() const3620   CanQualType getFoundHandlerType() const { return FoundHandlerType; }
3621 
operator ()(const CXXBaseSpecifier * S,CXXBasePath &)3622   bool operator()(const CXXBaseSpecifier *S, CXXBasePath &) {
3623     if (S->getAccessSpecifier() == AccessSpecifier::AS_public) {
3624       CatchHandlerType Check(S->getType(), CheckAgainstPointer);
3625       const auto &M = TypesToCheck;
3626       auto I = M.find(Check);
3627       if (I != M.end()) {
3628         FoundHandler = I->second;
3629         FoundHandlerType = Ctx.getCanonicalType(S->getType());
3630         return true;
3631       }
3632     }
3633     return false;
3634   }
3635 };
3636 }
3637 
3638 /// ActOnCXXTryBlock - Takes a try compound-statement and a number of
3639 /// handlers and creates a try statement from them.
ActOnCXXTryBlock(SourceLocation TryLoc,Stmt * TryBlock,ArrayRef<Stmt * > Handlers)3640 StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
3641                                   ArrayRef<Stmt *> Handlers) {
3642   // Don't report an error if 'try' is used in system headers.
3643   if (!getLangOpts().CXXExceptions &&
3644       !getSourceManager().isInSystemHeader(TryLoc))
3645     Diag(TryLoc, diag::err_exceptions_disabled) << "try";
3646 
3647   if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope())
3648     Diag(TryLoc, diag::err_omp_simd_region_cannot_use_stmt) << "try";
3649 
3650   sema::FunctionScopeInfo *FSI = getCurFunction();
3651 
3652   // C++ try is incompatible with SEH __try.
3653   if (!getLangOpts().Borland && FSI->FirstSEHTryLoc.isValid()) {
3654     Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
3655     Diag(FSI->FirstSEHTryLoc, diag::note_conflicting_try_here) << "'__try'";
3656   }
3657 
3658   const unsigned NumHandlers = Handlers.size();
3659   assert(!Handlers.empty() &&
3660          "The parser shouldn't call this if there are no handlers.");
3661 
3662   llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> HandledTypes;
3663   for (unsigned i = 0; i < NumHandlers; ++i) {
3664     CXXCatchStmt *H = cast<CXXCatchStmt>(Handlers[i]);
3665 
3666     // Diagnose when the handler is a catch-all handler, but it isn't the last
3667     // handler for the try block. [except.handle]p5. Also, skip exception
3668     // declarations that are invalid, since we can't usefully report on them.
3669     if (!H->getExceptionDecl()) {
3670       if (i < NumHandlers - 1)
3671         return StmtError(Diag(H->getLocStart(), diag::err_early_catch_all));
3672       continue;
3673     } else if (H->getExceptionDecl()->isInvalidDecl())
3674       continue;
3675 
3676     // Walk the type hierarchy to diagnose when this type has already been
3677     // handled (duplication), or cannot be handled (derivation inversion). We
3678     // ignore top-level cv-qualifiers, per [except.handle]p3
3679     CatchHandlerType HandlerCHT =
3680         (QualType)Context.getCanonicalType(H->getCaughtType());
3681 
3682     // We can ignore whether the type is a reference or a pointer; we need the
3683     // underlying declaration type in order to get at the underlying record
3684     // decl, if there is one.
3685     QualType Underlying = HandlerCHT.underlying();
3686     if (auto *RD = Underlying->getAsCXXRecordDecl()) {
3687       if (!RD->hasDefinition())
3688         continue;
3689       // Check that none of the public, unambiguous base classes are in the
3690       // map ([except.handle]p1). Give the base classes the same pointer
3691       // qualification as the original type we are basing off of. This allows
3692       // comparison against the handler type using the same top-level pointer
3693       // as the original type.
3694       CXXBasePaths Paths;
3695       Paths.setOrigin(RD);
3696       CatchTypePublicBases CTPB(Context, HandledTypes, HandlerCHT.isPointer());
3697       if (RD->lookupInBases(CTPB, Paths)) {
3698         const CXXCatchStmt *Problem = CTPB.getFoundHandler();
3699         if (!Paths.isAmbiguous(CTPB.getFoundHandlerType())) {
3700           Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
3701                diag::warn_exception_caught_by_earlier_handler)
3702               << H->getCaughtType();
3703           Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
3704                 diag::note_previous_exception_handler)
3705               << Problem->getCaughtType();
3706         }
3707       }
3708     }
3709 
3710     // Add the type the list of ones we have handled; diagnose if we've already
3711     // handled it.
3712     auto R = HandledTypes.insert(std::make_pair(H->getCaughtType(), H));
3713     if (!R.second) {
3714       const CXXCatchStmt *Problem = R.first->second;
3715       Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
3716            diag::warn_exception_caught_by_earlier_handler)
3717           << H->getCaughtType();
3718       Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
3719            diag::note_previous_exception_handler)
3720           << Problem->getCaughtType();
3721     }
3722   }
3723 
3724   FSI->setHasCXXTry(TryLoc);
3725 
3726   return CXXTryStmt::Create(Context, TryLoc, TryBlock, Handlers);
3727 }
3728 
ActOnSEHTryBlock(bool IsCXXTry,SourceLocation TryLoc,Stmt * TryBlock,Stmt * Handler)3729 StmtResult Sema::ActOnSEHTryBlock(bool IsCXXTry, SourceLocation TryLoc,
3730                                   Stmt *TryBlock, Stmt *Handler) {
3731   assert(TryBlock && Handler);
3732 
3733   sema::FunctionScopeInfo *FSI = getCurFunction();
3734 
3735   // SEH __try is incompatible with C++ try. Borland appears to support this,
3736   // however.
3737   if (!getLangOpts().Borland) {
3738     if (FSI->FirstCXXTryLoc.isValid()) {
3739       Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
3740       Diag(FSI->FirstCXXTryLoc, diag::note_conflicting_try_here) << "'try'";
3741     }
3742   }
3743 
3744   FSI->setHasSEHTry(TryLoc);
3745 
3746   // Reject __try in Obj-C methods, blocks, and captured decls, since we don't
3747   // track if they use SEH.
3748   DeclContext *DC = CurContext;
3749   while (DC && !DC->isFunctionOrMethod())
3750     DC = DC->getParent();
3751   FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(DC);
3752   if (FD)
3753     FD->setUsesSEHTry(true);
3754   else
3755     Diag(TryLoc, diag::err_seh_try_outside_functions);
3756 
3757   // Reject __try on unsupported targets.
3758   if (!Context.getTargetInfo().isSEHTrySupported())
3759     Diag(TryLoc, diag::err_seh_try_unsupported);
3760 
3761   return SEHTryStmt::Create(Context, IsCXXTry, TryLoc, TryBlock, Handler);
3762 }
3763 
3764 StmtResult
ActOnSEHExceptBlock(SourceLocation Loc,Expr * FilterExpr,Stmt * Block)3765 Sema::ActOnSEHExceptBlock(SourceLocation Loc,
3766                           Expr *FilterExpr,
3767                           Stmt *Block) {
3768   assert(FilterExpr && Block);
3769 
3770   if(!FilterExpr->getType()->isIntegerType()) {
3771     return StmtError(Diag(FilterExpr->getExprLoc(),
3772                      diag::err_filter_expression_integral)
3773                      << FilterExpr->getType());
3774   }
3775 
3776   return SEHExceptStmt::Create(Context,Loc,FilterExpr,Block);
3777 }
3778 
ActOnStartSEHFinallyBlock()3779 void Sema::ActOnStartSEHFinallyBlock() {
3780   CurrentSEHFinally.push_back(CurScope);
3781 }
3782 
ActOnAbortSEHFinallyBlock()3783 void Sema::ActOnAbortSEHFinallyBlock() {
3784   CurrentSEHFinally.pop_back();
3785 }
3786 
ActOnFinishSEHFinallyBlock(SourceLocation Loc,Stmt * Block)3787 StmtResult Sema::ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block) {
3788   assert(Block);
3789   CurrentSEHFinally.pop_back();
3790   return SEHFinallyStmt::Create(Context, Loc, Block);
3791 }
3792 
3793 StmtResult
ActOnSEHLeaveStmt(SourceLocation Loc,Scope * CurScope)3794 Sema::ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope) {
3795   Scope *SEHTryParent = CurScope;
3796   while (SEHTryParent && !SEHTryParent->isSEHTryScope())
3797     SEHTryParent = SEHTryParent->getParent();
3798   if (!SEHTryParent)
3799     return StmtError(Diag(Loc, diag::err_ms___leave_not_in___try));
3800   CheckJumpOutOfSEHFinally(*this, Loc, *SEHTryParent);
3801 
3802   return new (Context) SEHLeaveStmt(Loc);
3803 }
3804 
BuildMSDependentExistsStmt(SourceLocation KeywordLoc,bool IsIfExists,NestedNameSpecifierLoc QualifierLoc,DeclarationNameInfo NameInfo,Stmt * Nested)3805 StmtResult Sema::BuildMSDependentExistsStmt(SourceLocation KeywordLoc,
3806                                             bool IsIfExists,
3807                                             NestedNameSpecifierLoc QualifierLoc,
3808                                             DeclarationNameInfo NameInfo,
3809                                             Stmt *Nested)
3810 {
3811   return new (Context) MSDependentExistsStmt(KeywordLoc, IsIfExists,
3812                                              QualifierLoc, NameInfo,
3813                                              cast<CompoundStmt>(Nested));
3814 }
3815 
3816 
ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,bool IsIfExists,CXXScopeSpec & SS,UnqualifiedId & Name,Stmt * Nested)3817 StmtResult Sema::ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,
3818                                             bool IsIfExists,
3819                                             CXXScopeSpec &SS,
3820                                             UnqualifiedId &Name,
3821                                             Stmt *Nested) {
3822   return BuildMSDependentExistsStmt(KeywordLoc, IsIfExists,
3823                                     SS.getWithLocInContext(Context),
3824                                     GetNameFromUnqualifiedId(Name),
3825                                     Nested);
3826 }
3827 
3828 RecordDecl*
CreateCapturedStmtRecordDecl(CapturedDecl * & CD,SourceLocation Loc,unsigned NumParams)3829 Sema::CreateCapturedStmtRecordDecl(CapturedDecl *&CD, SourceLocation Loc,
3830                                    unsigned NumParams) {
3831   DeclContext *DC = CurContext;
3832   while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
3833     DC = DC->getParent();
3834 
3835   RecordDecl *RD = nullptr;
3836   if (getLangOpts().CPlusPlus)
3837     RD = CXXRecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc,
3838                                /*Id=*/nullptr);
3839   else
3840     RD = RecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc, /*Id=*/nullptr);
3841 
3842   RD->setCapturedRecord();
3843   DC->addDecl(RD);
3844   RD->setImplicit();
3845   RD->startDefinition();
3846 
3847   assert(NumParams > 0 && "CapturedStmt requires context parameter");
3848   CD = CapturedDecl::Create(Context, CurContext, NumParams);
3849   DC->addDecl(CD);
3850   return RD;
3851 }
3852 
buildCapturedStmtCaptureList(SmallVectorImpl<CapturedStmt::Capture> & Captures,SmallVectorImpl<Expr * > & CaptureInits,ArrayRef<CapturingScopeInfo::Capture> Candidates)3853 static void buildCapturedStmtCaptureList(
3854     SmallVectorImpl<CapturedStmt::Capture> &Captures,
3855     SmallVectorImpl<Expr *> &CaptureInits,
3856     ArrayRef<CapturingScopeInfo::Capture> Candidates) {
3857 
3858   typedef ArrayRef<CapturingScopeInfo::Capture>::const_iterator CaptureIter;
3859   for (CaptureIter Cap = Candidates.begin(); Cap != Candidates.end(); ++Cap) {
3860 
3861     if (Cap->isThisCapture()) {
3862       Captures.push_back(CapturedStmt::Capture(Cap->getLocation(),
3863                                                CapturedStmt::VCK_This));
3864       CaptureInits.push_back(Cap->getInitExpr());
3865       continue;
3866     } else if (Cap->isVLATypeCapture()) {
3867       Captures.push_back(
3868           CapturedStmt::Capture(Cap->getLocation(), CapturedStmt::VCK_VLAType));
3869       CaptureInits.push_back(nullptr);
3870       continue;
3871     }
3872 
3873     Captures.push_back(CapturedStmt::Capture(Cap->getLocation(),
3874                                              Cap->isReferenceCapture()
3875                                                  ? CapturedStmt::VCK_ByRef
3876                                                  : CapturedStmt::VCK_ByCopy,
3877                                              Cap->getVariable()));
3878     CaptureInits.push_back(Cap->getInitExpr());
3879   }
3880 }
3881 
ActOnCapturedRegionStart(SourceLocation Loc,Scope * CurScope,CapturedRegionKind Kind,unsigned NumParams)3882 void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
3883                                     CapturedRegionKind Kind,
3884                                     unsigned NumParams) {
3885   CapturedDecl *CD = nullptr;
3886   RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, NumParams);
3887 
3888   // Build the context parameter
3889   DeclContext *DC = CapturedDecl::castToDeclContext(CD);
3890   IdentifierInfo *ParamName = &Context.Idents.get("__context");
3891   QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
3892   ImplicitParamDecl *Param
3893     = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType);
3894   DC->addDecl(Param);
3895 
3896   CD->setContextParam(0, Param);
3897 
3898   // Enter the capturing scope for this captured region.
3899   PushCapturedRegionScope(CurScope, CD, RD, Kind);
3900 
3901   if (CurScope)
3902     PushDeclContext(CurScope, CD);
3903   else
3904     CurContext = CD;
3905 
3906   PushExpressionEvaluationContext(PotentiallyEvaluated);
3907 }
3908 
ActOnCapturedRegionStart(SourceLocation Loc,Scope * CurScope,CapturedRegionKind Kind,ArrayRef<CapturedParamNameType> Params)3909 void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
3910                                     CapturedRegionKind Kind,
3911                                     ArrayRef<CapturedParamNameType> Params) {
3912   CapturedDecl *CD = nullptr;
3913   RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, Params.size());
3914 
3915   // Build the context parameter
3916   DeclContext *DC = CapturedDecl::castToDeclContext(CD);
3917   bool ContextIsFound = false;
3918   unsigned ParamNum = 0;
3919   for (ArrayRef<CapturedParamNameType>::iterator I = Params.begin(),
3920                                                  E = Params.end();
3921        I != E; ++I, ++ParamNum) {
3922     if (I->second.isNull()) {
3923       assert(!ContextIsFound &&
3924              "null type has been found already for '__context' parameter");
3925       IdentifierInfo *ParamName = &Context.Idents.get("__context");
3926       QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
3927       ImplicitParamDecl *Param
3928         = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType);
3929       DC->addDecl(Param);
3930       CD->setContextParam(ParamNum, Param);
3931       ContextIsFound = true;
3932     } else {
3933       IdentifierInfo *ParamName = &Context.Idents.get(I->first);
3934       ImplicitParamDecl *Param
3935         = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, I->second);
3936       DC->addDecl(Param);
3937       CD->setParam(ParamNum, Param);
3938     }
3939   }
3940   assert(ContextIsFound && "no null type for '__context' parameter");
3941   if (!ContextIsFound) {
3942     // Add __context implicitly if it is not specified.
3943     IdentifierInfo *ParamName = &Context.Idents.get("__context");
3944     QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
3945     ImplicitParamDecl *Param =
3946         ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType);
3947     DC->addDecl(Param);
3948     CD->setContextParam(ParamNum, Param);
3949   }
3950   // Enter the capturing scope for this captured region.
3951   PushCapturedRegionScope(CurScope, CD, RD, Kind);
3952 
3953   if (CurScope)
3954     PushDeclContext(CurScope, CD);
3955   else
3956     CurContext = CD;
3957 
3958   PushExpressionEvaluationContext(PotentiallyEvaluated);
3959 }
3960 
ActOnCapturedRegionError()3961 void Sema::ActOnCapturedRegionError() {
3962   DiscardCleanupsInEvaluationContext();
3963   PopExpressionEvaluationContext();
3964 
3965   CapturedRegionScopeInfo *RSI = getCurCapturedRegion();
3966   RecordDecl *Record = RSI->TheRecordDecl;
3967   Record->setInvalidDecl();
3968 
3969   SmallVector<Decl*, 4> Fields(Record->fields());
3970   ActOnFields(/*Scope=*/nullptr, Record->getLocation(), Record, Fields,
3971               SourceLocation(), SourceLocation(), /*AttributeList=*/nullptr);
3972 
3973   PopDeclContext();
3974   PopFunctionScopeInfo();
3975 }
3976 
ActOnCapturedRegionEnd(Stmt * S)3977 StmtResult Sema::ActOnCapturedRegionEnd(Stmt *S) {
3978   CapturedRegionScopeInfo *RSI = getCurCapturedRegion();
3979 
3980   SmallVector<CapturedStmt::Capture, 4> Captures;
3981   SmallVector<Expr *, 4> CaptureInits;
3982   buildCapturedStmtCaptureList(Captures, CaptureInits, RSI->Captures);
3983 
3984   CapturedDecl *CD = RSI->TheCapturedDecl;
3985   RecordDecl *RD = RSI->TheRecordDecl;
3986 
3987   CapturedStmt *Res = CapturedStmt::Create(
3988       getASTContext(), S, static_cast<CapturedRegionKind>(RSI->CapRegionKind),
3989       Captures, CaptureInits, CD, RD);
3990 
3991   CD->setBody(Res->getCapturedStmt());
3992   RD->completeDefinition();
3993 
3994   DiscardCleanupsInEvaluationContext();
3995   PopExpressionEvaluationContext();
3996 
3997   PopDeclContext();
3998   PopFunctionScopeInfo();
3999 
4000   return Res;
4001 }
4002