1 //===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements semantic analysis for statements.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "clang/AST/ASTContext.h"
14 #include "clang/AST/ASTDiagnostic.h"
15 #include "clang/AST/ASTLambda.h"
16 #include "clang/AST/CXXInheritance.h"
17 #include "clang/AST/CharUnits.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/EvaluatedExprVisitor.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/ExprObjC.h"
22 #include "clang/AST/IgnoreExpr.h"
23 #include "clang/AST/RecursiveASTVisitor.h"
24 #include "clang/AST/StmtCXX.h"
25 #include "clang/AST/StmtObjC.h"
26 #include "clang/AST/TypeLoc.h"
27 #include "clang/AST/TypeOrdering.h"
28 #include "clang/Basic/TargetInfo.h"
29 #include "clang/Lex/Preprocessor.h"
30 #include "clang/Sema/Initialization.h"
31 #include "clang/Sema/Lookup.h"
32 #include "clang/Sema/Ownership.h"
33 #include "clang/Sema/Scope.h"
34 #include "clang/Sema/ScopeInfo.h"
35 #include "clang/Sema/SemaInternal.h"
36 #include "llvm/ADT/ArrayRef.h"
37 #include "llvm/ADT/DenseMap.h"
38 #include "llvm/ADT/STLExtras.h"
39 #include "llvm/ADT/SmallPtrSet.h"
40 #include "llvm/ADT/SmallString.h"
41 #include "llvm/ADT/SmallVector.h"
42
43 using namespace clang;
44 using namespace sema;
45
ActOnExprStmt(ExprResult FE,bool DiscardedValue)46 StmtResult Sema::ActOnExprStmt(ExprResult FE, bool DiscardedValue) {
47 if (FE.isInvalid())
48 return StmtError();
49
50 FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(), DiscardedValue);
51 if (FE.isInvalid())
52 return StmtError();
53
54 // C99 6.8.3p2: The expression in an expression statement is evaluated as a
55 // void expression for its side effects. Conversion to void allows any
56 // operand, even incomplete types.
57
58 // Same thing in for stmt first clause (when expr) and third clause.
59 return StmtResult(FE.getAs<Stmt>());
60 }
61
62
ActOnExprStmtError()63 StmtResult Sema::ActOnExprStmtError() {
64 DiscardCleanupsInEvaluationContext();
65 return StmtError();
66 }
67
ActOnNullStmt(SourceLocation SemiLoc,bool HasLeadingEmptyMacro)68 StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc,
69 bool HasLeadingEmptyMacro) {
70 return new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro);
71 }
72
ActOnDeclStmt(DeclGroupPtrTy dg,SourceLocation StartLoc,SourceLocation EndLoc)73 StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc,
74 SourceLocation EndLoc) {
75 DeclGroupRef DG = dg.get();
76
77 // If we have an invalid decl, just return an error.
78 if (DG.isNull()) return StmtError();
79
80 return new (Context) DeclStmt(DG, StartLoc, EndLoc);
81 }
82
ActOnForEachDeclStmt(DeclGroupPtrTy dg)83 void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
84 DeclGroupRef DG = dg.get();
85
86 // If we don't have a declaration, or we have an invalid declaration,
87 // just return.
88 if (DG.isNull() || !DG.isSingleDecl())
89 return;
90
91 Decl *decl = DG.getSingleDecl();
92 if (!decl || decl->isInvalidDecl())
93 return;
94
95 // Only variable declarations are permitted.
96 VarDecl *var = dyn_cast<VarDecl>(decl);
97 if (!var) {
98 Diag(decl->getLocation(), diag::err_non_variable_decl_in_for);
99 decl->setInvalidDecl();
100 return;
101 }
102
103 // foreach variables are never actually initialized in the way that
104 // the parser came up with.
105 var->setInit(nullptr);
106
107 // In ARC, we don't need to retain the iteration variable of a fast
108 // enumeration loop. Rather than actually trying to catch that
109 // during declaration processing, we remove the consequences here.
110 if (getLangOpts().ObjCAutoRefCount) {
111 QualType type = var->getType();
112
113 // Only do this if we inferred the lifetime. Inferred lifetime
114 // will show up as a local qualifier because explicit lifetime
115 // should have shown up as an AttributedType instead.
116 if (type.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong) {
117 // Add 'const' and mark the variable as pseudo-strong.
118 var->setType(type.withConst());
119 var->setARCPseudoStrong(true);
120 }
121 }
122 }
123
124 /// Diagnose unused comparisons, both builtin and overloaded operators.
125 /// For '==' and '!=', suggest fixits for '=' or '|='.
126 ///
127 /// Adding a cast to void (or other expression wrappers) will prevent the
128 /// warning from firing.
DiagnoseUnusedComparison(Sema & S,const Expr * E)129 static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) {
130 SourceLocation Loc;
131 bool CanAssign;
132 enum { Equality, Inequality, Relational, ThreeWay } Kind;
133
134 if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
135 if (!Op->isComparisonOp())
136 return false;
137
138 if (Op->getOpcode() == BO_EQ)
139 Kind = Equality;
140 else if (Op->getOpcode() == BO_NE)
141 Kind = Inequality;
142 else if (Op->getOpcode() == BO_Cmp)
143 Kind = ThreeWay;
144 else {
145 assert(Op->isRelationalOp());
146 Kind = Relational;
147 }
148 Loc = Op->getOperatorLoc();
149 CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
150 } else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
151 switch (Op->getOperator()) {
152 case OO_EqualEqual:
153 Kind = Equality;
154 break;
155 case OO_ExclaimEqual:
156 Kind = Inequality;
157 break;
158 case OO_Less:
159 case OO_Greater:
160 case OO_GreaterEqual:
161 case OO_LessEqual:
162 Kind = Relational;
163 break;
164 case OO_Spaceship:
165 Kind = ThreeWay;
166 break;
167 default:
168 return false;
169 }
170
171 Loc = Op->getOperatorLoc();
172 CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
173 } else {
174 // Not a typo-prone comparison.
175 return false;
176 }
177
178 // Suppress warnings when the operator, suspicious as it may be, comes from
179 // a macro expansion.
180 if (S.SourceMgr.isMacroBodyExpansion(Loc))
181 return false;
182
183 S.Diag(Loc, diag::warn_unused_comparison)
184 << (unsigned)Kind << E->getSourceRange();
185
186 // If the LHS is a plausible entity to assign to, provide a fixit hint to
187 // correct common typos.
188 if (CanAssign) {
189 if (Kind == Inequality)
190 S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
191 << FixItHint::CreateReplacement(Loc, "|=");
192 else if (Kind == Equality)
193 S.Diag(Loc, diag::note_equality_comparison_to_assign)
194 << FixItHint::CreateReplacement(Loc, "=");
195 }
196
197 return true;
198 }
199
DiagnoseNoDiscard(Sema & S,const WarnUnusedResultAttr * A,SourceLocation Loc,SourceRange R1,SourceRange R2,bool IsCtor)200 static bool DiagnoseNoDiscard(Sema &S, const WarnUnusedResultAttr *A,
201 SourceLocation Loc, SourceRange R1,
202 SourceRange R2, bool IsCtor) {
203 if (!A)
204 return false;
205 StringRef Msg = A->getMessage();
206
207 if (Msg.empty()) {
208 if (IsCtor)
209 return S.Diag(Loc, diag::warn_unused_constructor) << A << R1 << R2;
210 return S.Diag(Loc, diag::warn_unused_result) << A << R1 << R2;
211 }
212
213 if (IsCtor)
214 return S.Diag(Loc, diag::warn_unused_constructor_msg) << A << Msg << R1
215 << R2;
216 return S.Diag(Loc, diag::warn_unused_result_msg) << A << Msg << R1 << R2;
217 }
218
DiagnoseUnusedExprResult(const Stmt * S)219 void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
220 if (const LabelStmt *Label = dyn_cast_or_null<LabelStmt>(S))
221 return DiagnoseUnusedExprResult(Label->getSubStmt());
222
223 const Expr *E = dyn_cast_or_null<Expr>(S);
224 if (!E)
225 return;
226
227 // If we are in an unevaluated expression context, then there can be no unused
228 // results because the results aren't expected to be used in the first place.
229 if (isUnevaluatedContext())
230 return;
231
232 SourceLocation ExprLoc = E->IgnoreParenImpCasts()->getExprLoc();
233 // In most cases, we don't want to warn if the expression is written in a
234 // macro body, or if the macro comes from a system header. If the offending
235 // expression is a call to a function with the warn_unused_result attribute,
236 // we warn no matter the location. Because of the order in which the various
237 // checks need to happen, we factor out the macro-related test here.
238 bool ShouldSuppress =
239 SourceMgr.isMacroBodyExpansion(ExprLoc) ||
240 SourceMgr.isInSystemMacro(ExprLoc);
241
242 const Expr *WarnExpr;
243 SourceLocation Loc;
244 SourceRange R1, R2;
245 if (!E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context))
246 return;
247
248 // If this is a GNU statement expression expanded from a macro, it is probably
249 // unused because it is a function-like macro that can be used as either an
250 // expression or statement. Don't warn, because it is almost certainly a
251 // false positive.
252 if (isa<StmtExpr>(E) && Loc.isMacroID())
253 return;
254
255 // Check if this is the UNREFERENCED_PARAMETER from the Microsoft headers.
256 // That macro is frequently used to suppress "unused parameter" warnings,
257 // but its implementation makes clang's -Wunused-value fire. Prevent this.
258 if (isa<ParenExpr>(E->IgnoreImpCasts()) && Loc.isMacroID()) {
259 SourceLocation SpellLoc = Loc;
260 if (findMacroSpelling(SpellLoc, "UNREFERENCED_PARAMETER"))
261 return;
262 }
263
264 // Okay, we have an unused result. Depending on what the base expression is,
265 // we might want to make a more specific diagnostic. Check for one of these
266 // cases now.
267 unsigned DiagID = diag::warn_unused_expr;
268 if (const FullExpr *Temps = dyn_cast<FullExpr>(E))
269 E = Temps->getSubExpr();
270 if (const CXXBindTemporaryExpr *TempExpr = dyn_cast<CXXBindTemporaryExpr>(E))
271 E = TempExpr->getSubExpr();
272
273 if (DiagnoseUnusedComparison(*this, E))
274 return;
275
276 E = WarnExpr;
277 if (const auto *Cast = dyn_cast<CastExpr>(E))
278 if (Cast->getCastKind() == CK_NoOp ||
279 Cast->getCastKind() == CK_ConstructorConversion)
280 E = Cast->getSubExpr()->IgnoreImpCasts();
281
282 if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
283 if (E->getType()->isVoidType())
284 return;
285
286 if (DiagnoseNoDiscard(*this, cast_or_null<WarnUnusedResultAttr>(
287 CE->getUnusedResultAttr(Context)),
288 Loc, R1, R2, /*isCtor=*/false))
289 return;
290
291 // If the callee has attribute pure, const, or warn_unused_result, warn with
292 // a more specific message to make it clear what is happening. If the call
293 // is written in a macro body, only warn if it has the warn_unused_result
294 // attribute.
295 if (const Decl *FD = CE->getCalleeDecl()) {
296 if (ShouldSuppress)
297 return;
298 if (FD->hasAttr<PureAttr>()) {
299 Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
300 return;
301 }
302 if (FD->hasAttr<ConstAttr>()) {
303 Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
304 return;
305 }
306 }
307 } else if (const auto *CE = dyn_cast<CXXConstructExpr>(E)) {
308 if (const CXXConstructorDecl *Ctor = CE->getConstructor()) {
309 const auto *A = Ctor->getAttr<WarnUnusedResultAttr>();
310 A = A ? A : Ctor->getParent()->getAttr<WarnUnusedResultAttr>();
311 if (DiagnoseNoDiscard(*this, A, Loc, R1, R2, /*isCtor=*/true))
312 return;
313 }
314 } else if (const auto *ILE = dyn_cast<InitListExpr>(E)) {
315 if (const TagDecl *TD = ILE->getType()->getAsTagDecl()) {
316
317 if (DiagnoseNoDiscard(*this, TD->getAttr<WarnUnusedResultAttr>(), Loc, R1,
318 R2, /*isCtor=*/false))
319 return;
320 }
321 } else if (ShouldSuppress)
322 return;
323
324 E = WarnExpr;
325 if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
326 if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) {
327 Diag(Loc, diag::err_arc_unused_init_message) << R1;
328 return;
329 }
330 const ObjCMethodDecl *MD = ME->getMethodDecl();
331 if (MD) {
332 if (DiagnoseNoDiscard(*this, MD->getAttr<WarnUnusedResultAttr>(), Loc, R1,
333 R2, /*isCtor=*/false))
334 return;
335 }
336 } else if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
337 const Expr *Source = POE->getSyntacticForm();
338 // Handle the actually selected call of an OpenMP specialized call.
339 if (LangOpts.OpenMP && isa<CallExpr>(Source) &&
340 POE->getNumSemanticExprs() == 1 &&
341 isa<CallExpr>(POE->getSemanticExpr(0)))
342 return DiagnoseUnusedExprResult(POE->getSemanticExpr(0));
343 if (isa<ObjCSubscriptRefExpr>(Source))
344 DiagID = diag::warn_unused_container_subscript_expr;
345 else
346 DiagID = diag::warn_unused_property_expr;
347 } else if (const CXXFunctionalCastExpr *FC
348 = dyn_cast<CXXFunctionalCastExpr>(E)) {
349 const Expr *E = FC->getSubExpr();
350 if (const CXXBindTemporaryExpr *TE = dyn_cast<CXXBindTemporaryExpr>(E))
351 E = TE->getSubExpr();
352 if (isa<CXXTemporaryObjectExpr>(E))
353 return;
354 if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(E))
355 if (const CXXRecordDecl *RD = CE->getType()->getAsCXXRecordDecl())
356 if (!RD->getAttr<WarnUnusedAttr>())
357 return;
358 }
359 // Diagnose "(void*) blah" as a typo for "(void) blah".
360 else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
361 TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
362 QualType T = TI->getType();
363
364 // We really do want to use the non-canonical type here.
365 if (T == Context.VoidPtrTy) {
366 PointerTypeLoc TL = TI->getTypeLoc().castAs<PointerTypeLoc>();
367
368 Diag(Loc, diag::warn_unused_voidptr)
369 << FixItHint::CreateRemoval(TL.getStarLoc());
370 return;
371 }
372 }
373
374 // Tell the user to assign it into a variable to force a volatile load if this
375 // isn't an array.
376 if (E->isGLValue() && E->getType().isVolatileQualified() &&
377 !E->getType()->isArrayType()) {
378 Diag(Loc, diag::warn_unused_volatile) << R1 << R2;
379 return;
380 }
381
382 DiagRuntimeBehavior(Loc, nullptr, PDiag(DiagID) << R1 << R2);
383 }
384
ActOnStartOfCompoundStmt(bool IsStmtExpr)385 void Sema::ActOnStartOfCompoundStmt(bool IsStmtExpr) {
386 PushCompoundScope(IsStmtExpr);
387 }
388
ActOnAfterCompoundStatementLeadingPragmas()389 void Sema::ActOnAfterCompoundStatementLeadingPragmas() {
390 if (getCurFPFeatures().isFPConstrained()) {
391 FunctionScopeInfo *FSI = getCurFunction();
392 assert(FSI);
393 FSI->setUsesFPIntrin();
394 }
395 }
396
ActOnFinishOfCompoundStmt()397 void Sema::ActOnFinishOfCompoundStmt() {
398 PopCompoundScope();
399 }
400
getCurCompoundScope() const401 sema::CompoundScopeInfo &Sema::getCurCompoundScope() const {
402 return getCurFunction()->CompoundScopes.back();
403 }
404
ActOnCompoundStmt(SourceLocation L,SourceLocation R,ArrayRef<Stmt * > Elts,bool isStmtExpr)405 StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
406 ArrayRef<Stmt *> Elts, bool isStmtExpr) {
407 const unsigned NumElts = Elts.size();
408
409 // If we're in C89 mode, check that we don't have any decls after stmts. If
410 // so, emit an extension diagnostic.
411 if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) {
412 // Note that __extension__ can be around a decl.
413 unsigned i = 0;
414 // Skip over all declarations.
415 for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
416 /*empty*/;
417
418 // We found the end of the list or a statement. Scan for another declstmt.
419 for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
420 /*empty*/;
421
422 if (i != NumElts) {
423 Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
424 Diag(D->getLocation(), diag::ext_mixed_decls_code);
425 }
426 }
427
428 // Check for suspicious empty body (null statement) in `for' and `while'
429 // statements. Don't do anything for template instantiations, this just adds
430 // noise.
431 if (NumElts != 0 && !CurrentInstantiationScope &&
432 getCurCompoundScope().HasEmptyLoopBodies) {
433 for (unsigned i = 0; i != NumElts - 1; ++i)
434 DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]);
435 }
436
437 return CompoundStmt::Create(Context, Elts, L, R);
438 }
439
440 ExprResult
ActOnCaseExpr(SourceLocation CaseLoc,ExprResult Val)441 Sema::ActOnCaseExpr(SourceLocation CaseLoc, ExprResult Val) {
442 if (!Val.get())
443 return Val;
444
445 if (DiagnoseUnexpandedParameterPack(Val.get()))
446 return ExprError();
447
448 // If we're not inside a switch, let the 'case' statement handling diagnose
449 // this. Just clean up after the expression as best we can.
450 if (getCurFunction()->SwitchStack.empty())
451 return ActOnFinishFullExpr(Val.get(), Val.get()->getExprLoc(), false,
452 getLangOpts().CPlusPlus11);
453
454 Expr *CondExpr =
455 getCurFunction()->SwitchStack.back().getPointer()->getCond();
456 if (!CondExpr)
457 return ExprError();
458 QualType CondType = CondExpr->getType();
459
460 auto CheckAndFinish = [&](Expr *E) {
461 if (CondType->isDependentType() || E->isTypeDependent())
462 return ExprResult(E);
463
464 if (getLangOpts().CPlusPlus11) {
465 // C++11 [stmt.switch]p2: the constant-expression shall be a converted
466 // constant expression of the promoted type of the switch condition.
467 llvm::APSInt TempVal;
468 return CheckConvertedConstantExpression(E, CondType, TempVal,
469 CCEK_CaseValue);
470 }
471
472 ExprResult ER = E;
473 if (!E->isValueDependent())
474 ER = VerifyIntegerConstantExpression(E, AllowFold);
475 if (!ER.isInvalid())
476 ER = DefaultLvalueConversion(ER.get());
477 if (!ER.isInvalid())
478 ER = ImpCastExprToType(ER.get(), CondType, CK_IntegralCast);
479 if (!ER.isInvalid())
480 ER = ActOnFinishFullExpr(ER.get(), ER.get()->getExprLoc(), false);
481 return ER;
482 };
483
484 ExprResult Converted = CorrectDelayedTyposInExpr(
485 Val, /*InitDecl=*/nullptr, /*RecoverUncorrectedTypos=*/false,
486 CheckAndFinish);
487 if (Converted.get() == Val.get())
488 Converted = CheckAndFinish(Val.get());
489 return Converted;
490 }
491
492 StmtResult
ActOnCaseStmt(SourceLocation CaseLoc,ExprResult LHSVal,SourceLocation DotDotDotLoc,ExprResult RHSVal,SourceLocation ColonLoc)493 Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHSVal,
494 SourceLocation DotDotDotLoc, ExprResult RHSVal,
495 SourceLocation ColonLoc) {
496 assert((LHSVal.isInvalid() || LHSVal.get()) && "missing LHS value");
497 assert((DotDotDotLoc.isInvalid() ? RHSVal.isUnset()
498 : RHSVal.isInvalid() || RHSVal.get()) &&
499 "missing RHS value");
500
501 if (getCurFunction()->SwitchStack.empty()) {
502 Diag(CaseLoc, diag::err_case_not_in_switch);
503 return StmtError();
504 }
505
506 if (LHSVal.isInvalid() || RHSVal.isInvalid()) {
507 getCurFunction()->SwitchStack.back().setInt(true);
508 return StmtError();
509 }
510
511 auto *CS = CaseStmt::Create(Context, LHSVal.get(), RHSVal.get(),
512 CaseLoc, DotDotDotLoc, ColonLoc);
513 getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(CS);
514 return CS;
515 }
516
517 /// ActOnCaseStmtBody - This installs a statement as the body of a case.
ActOnCaseStmtBody(Stmt * S,Stmt * SubStmt)518 void Sema::ActOnCaseStmtBody(Stmt *S, Stmt *SubStmt) {
519 cast<CaseStmt>(S)->setSubStmt(SubStmt);
520 }
521
522 StmtResult
ActOnDefaultStmt(SourceLocation DefaultLoc,SourceLocation ColonLoc,Stmt * SubStmt,Scope * CurScope)523 Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
524 Stmt *SubStmt, Scope *CurScope) {
525 if (getCurFunction()->SwitchStack.empty()) {
526 Diag(DefaultLoc, diag::err_default_not_in_switch);
527 return SubStmt;
528 }
529
530 DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
531 getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(DS);
532 return DS;
533 }
534
535 StmtResult
ActOnLabelStmt(SourceLocation IdentLoc,LabelDecl * TheDecl,SourceLocation ColonLoc,Stmt * SubStmt)536 Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
537 SourceLocation ColonLoc, Stmt *SubStmt) {
538 // If the label was multiply defined, reject it now.
539 if (TheDecl->getStmt()) {
540 Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName();
541 Diag(TheDecl->getLocation(), diag::note_previous_definition);
542 return SubStmt;
543 }
544
545 ReservedIdentifierStatus Status = TheDecl->isReserved(getLangOpts());
546 if (Status != ReservedIdentifierStatus::NotReserved &&
547 !Context.getSourceManager().isInSystemHeader(IdentLoc))
548 Diag(IdentLoc, diag::warn_reserved_extern_symbol)
549 << TheDecl << static_cast<int>(Status);
550
551 // Otherwise, things are good. Fill in the declaration and return it.
552 LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt);
553 TheDecl->setStmt(LS);
554 if (!TheDecl->isGnuLocal()) {
555 TheDecl->setLocStart(IdentLoc);
556 if (!TheDecl->isMSAsmLabel()) {
557 // Don't update the location of MS ASM labels. These will result in
558 // a diagnostic, and changing the location here will mess that up.
559 TheDecl->setLocation(IdentLoc);
560 }
561 }
562 return LS;
563 }
564
BuildAttributedStmt(SourceLocation AttrsLoc,ArrayRef<const Attr * > Attrs,Stmt * SubStmt)565 StmtResult Sema::BuildAttributedStmt(SourceLocation AttrsLoc,
566 ArrayRef<const Attr *> Attrs,
567 Stmt *SubStmt) {
568 // FIXME: this code should move when a planned refactoring around statement
569 // attributes lands.
570 for (const auto *A : Attrs) {
571 if (A->getKind() == attr::MustTail) {
572 if (!checkAndRewriteMustTailAttr(SubStmt, *A)) {
573 return SubStmt;
574 }
575 setFunctionHasMustTail();
576 }
577 }
578
579 return AttributedStmt::Create(Context, AttrsLoc, Attrs, SubStmt);
580 }
581
ActOnAttributedStmt(const ParsedAttributesWithRange & Attrs,Stmt * SubStmt)582 StmtResult Sema::ActOnAttributedStmt(const ParsedAttributesWithRange &Attrs,
583 Stmt *SubStmt) {
584 SmallVector<const Attr *, 1> SemanticAttrs;
585 ProcessStmtAttributes(SubStmt, Attrs, SemanticAttrs);
586 if (!SemanticAttrs.empty())
587 return BuildAttributedStmt(Attrs.Range.getBegin(), SemanticAttrs, SubStmt);
588 // If none of the attributes applied, that's fine, we can recover by
589 // returning the substatement directly instead of making an AttributedStmt
590 // with no attributes on it.
591 return SubStmt;
592 }
593
checkAndRewriteMustTailAttr(Stmt * St,const Attr & MTA)594 bool Sema::checkAndRewriteMustTailAttr(Stmt *St, const Attr &MTA) {
595 ReturnStmt *R = cast<ReturnStmt>(St);
596 Expr *E = R->getRetValue();
597
598 if (CurContext->isDependentContext() || (E && E->isInstantiationDependent()))
599 // We have to suspend our check until template instantiation time.
600 return true;
601
602 if (!checkMustTailAttr(St, MTA))
603 return false;
604
605 // FIXME: Replace Expr::IgnoreImplicitAsWritten() with this function.
606 // Currently it does not skip implicit constructors in an initialization
607 // context.
608 auto IgnoreImplicitAsWritten = [](Expr *E) -> Expr * {
609 return IgnoreExprNodes(E, IgnoreImplicitAsWrittenSingleStep,
610 IgnoreElidableImplicitConstructorSingleStep);
611 };
612
613 // Now that we have verified that 'musttail' is valid here, rewrite the
614 // return value to remove all implicit nodes, but retain parentheses.
615 R->setRetValue(IgnoreImplicitAsWritten(E));
616 return true;
617 }
618
checkMustTailAttr(const Stmt * St,const Attr & MTA)619 bool Sema::checkMustTailAttr(const Stmt *St, const Attr &MTA) {
620 assert(!CurContext->isDependentContext() &&
621 "musttail cannot be checked from a dependent context");
622
623 // FIXME: Add Expr::IgnoreParenImplicitAsWritten() with this definition.
624 auto IgnoreParenImplicitAsWritten = [](const Expr *E) -> const Expr * {
625 return IgnoreExprNodes(const_cast<Expr *>(E), IgnoreParensSingleStep,
626 IgnoreImplicitAsWrittenSingleStep,
627 IgnoreElidableImplicitConstructorSingleStep);
628 };
629
630 const Expr *E = cast<ReturnStmt>(St)->getRetValue();
631 const auto *CE = dyn_cast_or_null<CallExpr>(IgnoreParenImplicitAsWritten(E));
632
633 if (!CE) {
634 Diag(St->getBeginLoc(), diag::err_musttail_needs_call) << &MTA;
635 return false;
636 }
637
638 if (const auto *EWC = dyn_cast<ExprWithCleanups>(E)) {
639 if (EWC->cleanupsHaveSideEffects()) {
640 Diag(St->getBeginLoc(), diag::err_musttail_needs_trivial_args) << &MTA;
641 return false;
642 }
643 }
644
645 // We need to determine the full function type (including "this" type, if any)
646 // for both caller and callee.
647 struct FuncType {
648 enum {
649 ft_non_member,
650 ft_static_member,
651 ft_non_static_member,
652 ft_pointer_to_member,
653 } MemberType = ft_non_member;
654
655 QualType This;
656 const FunctionProtoType *Func;
657 const CXXMethodDecl *Method = nullptr;
658 } CallerType, CalleeType;
659
660 auto GetMethodType = [this, St, MTA](const CXXMethodDecl *CMD, FuncType &Type,
661 bool IsCallee) -> bool {
662 if (isa<CXXConstructorDecl, CXXDestructorDecl>(CMD)) {
663 Diag(St->getBeginLoc(), diag::err_musttail_structors_forbidden)
664 << IsCallee << isa<CXXDestructorDecl>(CMD);
665 if (IsCallee)
666 Diag(CMD->getBeginLoc(), diag::note_musttail_structors_forbidden)
667 << isa<CXXDestructorDecl>(CMD);
668 Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
669 return false;
670 }
671 if (CMD->isStatic())
672 Type.MemberType = FuncType::ft_static_member;
673 else {
674 Type.This = CMD->getThisType()->getPointeeType();
675 Type.MemberType = FuncType::ft_non_static_member;
676 }
677 Type.Func = CMD->getType()->castAs<FunctionProtoType>();
678 return true;
679 };
680
681 const auto *CallerDecl = dyn_cast<FunctionDecl>(CurContext);
682
683 // Find caller function signature.
684 if (!CallerDecl) {
685 int ContextType;
686 if (isa<BlockDecl>(CurContext))
687 ContextType = 0;
688 else if (isa<ObjCMethodDecl>(CurContext))
689 ContextType = 1;
690 else
691 ContextType = 2;
692 Diag(St->getBeginLoc(), diag::err_musttail_forbidden_from_this_context)
693 << &MTA << ContextType;
694 return false;
695 } else if (const auto *CMD = dyn_cast<CXXMethodDecl>(CurContext)) {
696 // Caller is a class/struct method.
697 if (!GetMethodType(CMD, CallerType, false))
698 return false;
699 } else {
700 // Caller is a non-method function.
701 CallerType.Func = CallerDecl->getType()->getAs<FunctionProtoType>();
702 }
703
704 const Expr *CalleeExpr = CE->getCallee()->IgnoreParens();
705 const auto *CalleeBinOp = dyn_cast<BinaryOperator>(CalleeExpr);
706 SourceLocation CalleeLoc = CE->getCalleeDecl()
707 ? CE->getCalleeDecl()->getBeginLoc()
708 : St->getBeginLoc();
709
710 // Find callee function signature.
711 if (const CXXMethodDecl *CMD =
712 dyn_cast_or_null<CXXMethodDecl>(CE->getCalleeDecl())) {
713 // Call is: obj.method(), obj->method(), functor(), etc.
714 if (!GetMethodType(CMD, CalleeType, true))
715 return false;
716 } else if (CalleeBinOp && CalleeBinOp->isPtrMemOp()) {
717 // Call is: obj->*method_ptr or obj.*method_ptr
718 const auto *MPT =
719 CalleeBinOp->getRHS()->getType()->castAs<MemberPointerType>();
720 CalleeType.This = QualType(MPT->getClass(), 0);
721 CalleeType.Func = MPT->getPointeeType()->castAs<FunctionProtoType>();
722 CalleeType.MemberType = FuncType::ft_pointer_to_member;
723 } else if (isa<CXXPseudoDestructorExpr>(CalleeExpr)) {
724 Diag(St->getBeginLoc(), diag::err_musttail_structors_forbidden)
725 << /* IsCallee = */ 1 << /* IsDestructor = */ 1;
726 Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
727 return false;
728 } else {
729 // Non-method function.
730 CalleeType.Func =
731 CalleeExpr->getType()->getPointeeType()->getAs<FunctionProtoType>();
732 }
733
734 // Both caller and callee must have a prototype (no K&R declarations).
735 if (!CalleeType.Func || !CallerType.Func) {
736 Diag(St->getBeginLoc(), diag::err_musttail_needs_prototype) << &MTA;
737 if (!CalleeType.Func && CE->getDirectCallee()) {
738 Diag(CE->getDirectCallee()->getBeginLoc(),
739 diag::note_musttail_fix_non_prototype);
740 }
741 if (!CallerType.Func)
742 Diag(CallerDecl->getBeginLoc(), diag::note_musttail_fix_non_prototype);
743 return false;
744 }
745
746 // Caller and callee must have matching calling conventions.
747 //
748 // Some calling conventions are physically capable of supporting tail calls
749 // even if the function types don't perfectly match. LLVM is currently too
750 // strict to allow this, but if LLVM added support for this in the future, we
751 // could exit early here and skip the remaining checks if the functions are
752 // using such a calling convention.
753 if (CallerType.Func->getCallConv() != CalleeType.Func->getCallConv()) {
754 if (const auto *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl()))
755 Diag(St->getBeginLoc(), diag::err_musttail_callconv_mismatch)
756 << true << ND->getDeclName();
757 else
758 Diag(St->getBeginLoc(), diag::err_musttail_callconv_mismatch) << false;
759 Diag(CalleeLoc, diag::note_musttail_callconv_mismatch)
760 << FunctionType::getNameForCallConv(CallerType.Func->getCallConv())
761 << FunctionType::getNameForCallConv(CalleeType.Func->getCallConv());
762 Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
763 return false;
764 }
765
766 if (CalleeType.Func->isVariadic() || CallerType.Func->isVariadic()) {
767 Diag(St->getBeginLoc(), diag::err_musttail_no_variadic) << &MTA;
768 return false;
769 }
770
771 // Caller and callee must match in whether they have a "this" parameter.
772 if (CallerType.This.isNull() != CalleeType.This.isNull()) {
773 if (const auto *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
774 Diag(St->getBeginLoc(), diag::err_musttail_member_mismatch)
775 << CallerType.MemberType << CalleeType.MemberType << true
776 << ND->getDeclName();
777 Diag(CalleeLoc, diag::note_musttail_callee_defined_here)
778 << ND->getDeclName();
779 } else
780 Diag(St->getBeginLoc(), diag::err_musttail_member_mismatch)
781 << CallerType.MemberType << CalleeType.MemberType << false;
782 Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
783 return false;
784 }
785
786 auto CheckTypesMatch = [this](FuncType CallerType, FuncType CalleeType,
787 PartialDiagnostic &PD) -> bool {
788 enum {
789 ft_different_class,
790 ft_parameter_arity,
791 ft_parameter_mismatch,
792 ft_return_type,
793 };
794
795 auto DoTypesMatch = [this, &PD](QualType A, QualType B,
796 unsigned Select) -> bool {
797 if (!Context.hasSimilarType(A, B)) {
798 PD << Select << A.getUnqualifiedType() << B.getUnqualifiedType();
799 return false;
800 }
801 return true;
802 };
803
804 if (!CallerType.This.isNull() &&
805 !DoTypesMatch(CallerType.This, CalleeType.This, ft_different_class))
806 return false;
807
808 if (!DoTypesMatch(CallerType.Func->getReturnType(),
809 CalleeType.Func->getReturnType(), ft_return_type))
810 return false;
811
812 if (CallerType.Func->getNumParams() != CalleeType.Func->getNumParams()) {
813 PD << ft_parameter_arity << CallerType.Func->getNumParams()
814 << CalleeType.Func->getNumParams();
815 return false;
816 }
817
818 ArrayRef<QualType> CalleeParams = CalleeType.Func->getParamTypes();
819 ArrayRef<QualType> CallerParams = CallerType.Func->getParamTypes();
820 size_t N = CallerType.Func->getNumParams();
821 for (size_t I = 0; I < N; I++) {
822 if (!DoTypesMatch(CalleeParams[I], CallerParams[I],
823 ft_parameter_mismatch)) {
824 PD << static_cast<int>(I) + 1;
825 return false;
826 }
827 }
828
829 return true;
830 };
831
832 PartialDiagnostic PD = PDiag(diag::note_musttail_mismatch);
833 if (!CheckTypesMatch(CallerType, CalleeType, PD)) {
834 if (const auto *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl()))
835 Diag(St->getBeginLoc(), diag::err_musttail_mismatch)
836 << true << ND->getDeclName();
837 else
838 Diag(St->getBeginLoc(), diag::err_musttail_mismatch) << false;
839 Diag(CalleeLoc, PD);
840 Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA;
841 return false;
842 }
843
844 return true;
845 }
846
847 namespace {
848 class CommaVisitor : public EvaluatedExprVisitor<CommaVisitor> {
849 typedef EvaluatedExprVisitor<CommaVisitor> Inherited;
850 Sema &SemaRef;
851 public:
CommaVisitor(Sema & SemaRef)852 CommaVisitor(Sema &SemaRef) : Inherited(SemaRef.Context), SemaRef(SemaRef) {}
VisitBinaryOperator(BinaryOperator * E)853 void VisitBinaryOperator(BinaryOperator *E) {
854 if (E->getOpcode() == BO_Comma)
855 SemaRef.DiagnoseCommaOperator(E->getLHS(), E->getExprLoc());
856 EvaluatedExprVisitor<CommaVisitor>::VisitBinaryOperator(E);
857 }
858 };
859 }
860
ActOnIfStmt(SourceLocation IfLoc,bool IsConstexpr,SourceLocation LParenLoc,Stmt * InitStmt,ConditionResult Cond,SourceLocation RParenLoc,Stmt * thenStmt,SourceLocation ElseLoc,Stmt * elseStmt)861 StmtResult Sema::ActOnIfStmt(SourceLocation IfLoc, bool IsConstexpr,
862 SourceLocation LParenLoc, Stmt *InitStmt,
863 ConditionResult Cond, SourceLocation RParenLoc,
864 Stmt *thenStmt, SourceLocation ElseLoc,
865 Stmt *elseStmt) {
866 if (Cond.isInvalid())
867 Cond = ConditionResult(
868 *this, nullptr,
869 MakeFullExpr(new (Context) OpaqueValueExpr(SourceLocation(),
870 Context.BoolTy, VK_RValue),
871 IfLoc),
872 false);
873
874 Expr *CondExpr = Cond.get().second;
875 // Only call the CommaVisitor when not C89 due to differences in scope flags.
876 if ((getLangOpts().C99 || getLangOpts().CPlusPlus) &&
877 !Diags.isIgnored(diag::warn_comma_operator, CondExpr->getExprLoc()))
878 CommaVisitor(*this).Visit(CondExpr);
879
880 if (!elseStmt)
881 DiagnoseEmptyStmtBody(CondExpr->getEndLoc(), thenStmt,
882 diag::warn_empty_if_body);
883
884 if (IsConstexpr) {
885 auto DiagnoseLikelihood = [&](const Stmt *S) {
886 if (const Attr *A = Stmt::getLikelihoodAttr(S)) {
887 Diags.Report(A->getLocation(),
888 diag::warn_attribute_has_no_effect_on_if_constexpr)
889 << A << A->getRange();
890 Diags.Report(IfLoc,
891 diag::note_attribute_has_no_effect_on_if_constexpr_here)
892 << SourceRange(IfLoc, LParenLoc.getLocWithOffset(-1));
893 }
894 };
895 DiagnoseLikelihood(thenStmt);
896 DiagnoseLikelihood(elseStmt);
897 } else {
898 std::tuple<bool, const Attr *, const Attr *> LHC =
899 Stmt::determineLikelihoodConflict(thenStmt, elseStmt);
900 if (std::get<0>(LHC)) {
901 const Attr *ThenAttr = std::get<1>(LHC);
902 const Attr *ElseAttr = std::get<2>(LHC);
903 Diags.Report(ThenAttr->getLocation(),
904 diag::warn_attributes_likelihood_ifstmt_conflict)
905 << ThenAttr << ThenAttr->getRange();
906 Diags.Report(ElseAttr->getLocation(), diag::note_conflicting_attribute)
907 << ElseAttr << ElseAttr->getRange();
908 }
909 }
910
911 return BuildIfStmt(IfLoc, IsConstexpr, LParenLoc, InitStmt, Cond, RParenLoc,
912 thenStmt, ElseLoc, elseStmt);
913 }
914
BuildIfStmt(SourceLocation IfLoc,bool IsConstexpr,SourceLocation LParenLoc,Stmt * InitStmt,ConditionResult Cond,SourceLocation RParenLoc,Stmt * thenStmt,SourceLocation ElseLoc,Stmt * elseStmt)915 StmtResult Sema::BuildIfStmt(SourceLocation IfLoc, bool IsConstexpr,
916 SourceLocation LParenLoc, Stmt *InitStmt,
917 ConditionResult Cond, SourceLocation RParenLoc,
918 Stmt *thenStmt, SourceLocation ElseLoc,
919 Stmt *elseStmt) {
920 if (Cond.isInvalid())
921 return StmtError();
922
923 if (IsConstexpr || isa<ObjCAvailabilityCheckExpr>(Cond.get().second))
924 setFunctionHasBranchProtectedScope();
925
926 return IfStmt::Create(Context, IfLoc, IsConstexpr, InitStmt, Cond.get().first,
927 Cond.get().second, LParenLoc, RParenLoc, thenStmt,
928 ElseLoc, elseStmt);
929 }
930
931 namespace {
932 struct CaseCompareFunctor {
operator ()__anon58d0223e0c11::CaseCompareFunctor933 bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
934 const llvm::APSInt &RHS) {
935 return LHS.first < RHS;
936 }
operator ()__anon58d0223e0c11::CaseCompareFunctor937 bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
938 const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
939 return LHS.first < RHS.first;
940 }
operator ()__anon58d0223e0c11::CaseCompareFunctor941 bool operator()(const llvm::APSInt &LHS,
942 const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
943 return LHS < RHS.first;
944 }
945 };
946 }
947
948 /// CmpCaseVals - Comparison predicate for sorting case values.
949 ///
CmpCaseVals(const std::pair<llvm::APSInt,CaseStmt * > & lhs,const std::pair<llvm::APSInt,CaseStmt * > & rhs)950 static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
951 const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
952 if (lhs.first < rhs.first)
953 return true;
954
955 if (lhs.first == rhs.first &&
956 lhs.second->getCaseLoc() < rhs.second->getCaseLoc())
957 return true;
958 return false;
959 }
960
961 /// CmpEnumVals - Comparison predicate for sorting enumeration values.
962 ///
CmpEnumVals(const std::pair<llvm::APSInt,EnumConstantDecl * > & lhs,const std::pair<llvm::APSInt,EnumConstantDecl * > & rhs)963 static bool CmpEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
964 const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
965 {
966 return lhs.first < rhs.first;
967 }
968
969 /// EqEnumVals - Comparison preficate for uniqing enumeration values.
970 ///
EqEnumVals(const std::pair<llvm::APSInt,EnumConstantDecl * > & lhs,const std::pair<llvm::APSInt,EnumConstantDecl * > & rhs)971 static bool EqEnumVals(const std::pair<llvm::APSInt, EnumConstantDecl*>& lhs,
972 const std::pair<llvm::APSInt, EnumConstantDecl*>& rhs)
973 {
974 return lhs.first == rhs.first;
975 }
976
977 /// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
978 /// potentially integral-promoted expression @p expr.
GetTypeBeforeIntegralPromotion(const Expr * & E)979 static QualType GetTypeBeforeIntegralPromotion(const Expr *&E) {
980 if (const auto *FE = dyn_cast<FullExpr>(E))
981 E = FE->getSubExpr();
982 while (const auto *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
983 if (ImpCast->getCastKind() != CK_IntegralCast) break;
984 E = ImpCast->getSubExpr();
985 }
986 return E->getType();
987 }
988
CheckSwitchCondition(SourceLocation SwitchLoc,Expr * Cond)989 ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) {
990 class SwitchConvertDiagnoser : public ICEConvertDiagnoser {
991 Expr *Cond;
992
993 public:
994 SwitchConvertDiagnoser(Expr *Cond)
995 : ICEConvertDiagnoser(/*AllowScopedEnumerations*/true, false, true),
996 Cond(Cond) {}
997
998 SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
999 QualType T) override {
1000 return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T;
1001 }
1002
1003 SemaDiagnosticBuilder diagnoseIncomplete(
1004 Sema &S, SourceLocation Loc, QualType T) override {
1005 return S.Diag(Loc, diag::err_switch_incomplete_class_type)
1006 << T << Cond->getSourceRange();
1007 }
1008
1009 SemaDiagnosticBuilder diagnoseExplicitConv(
1010 Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
1011 return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy;
1012 }
1013
1014 SemaDiagnosticBuilder noteExplicitConv(
1015 Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
1016 return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
1017 << ConvTy->isEnumeralType() << ConvTy;
1018 }
1019
1020 SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
1021 QualType T) override {
1022 return S.Diag(Loc, diag::err_switch_multiple_conversions) << T;
1023 }
1024
1025 SemaDiagnosticBuilder noteAmbiguous(
1026 Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
1027 return S.Diag(Conv->getLocation(), diag::note_switch_conversion)
1028 << ConvTy->isEnumeralType() << ConvTy;
1029 }
1030
1031 SemaDiagnosticBuilder diagnoseConversion(
1032 Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
1033 llvm_unreachable("conversion functions are permitted");
1034 }
1035 } SwitchDiagnoser(Cond);
1036
1037 ExprResult CondResult =
1038 PerformContextualImplicitConversion(SwitchLoc, Cond, SwitchDiagnoser);
1039 if (CondResult.isInvalid())
1040 return ExprError();
1041
1042 // FIXME: PerformContextualImplicitConversion doesn't always tell us if it
1043 // failed and produced a diagnostic.
1044 Cond = CondResult.get();
1045 if (!Cond->isTypeDependent() &&
1046 !Cond->getType()->isIntegralOrEnumerationType())
1047 return ExprError();
1048
1049 // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
1050 return UsualUnaryConversions(Cond);
1051 }
1052
ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,SourceLocation LParenLoc,Stmt * InitStmt,ConditionResult Cond,SourceLocation RParenLoc)1053 StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
1054 SourceLocation LParenLoc,
1055 Stmt *InitStmt, ConditionResult Cond,
1056 SourceLocation RParenLoc) {
1057 Expr *CondExpr = Cond.get().second;
1058 assert((Cond.isInvalid() || CondExpr) && "switch with no condition");
1059
1060 if (CondExpr && !CondExpr->isTypeDependent()) {
1061 // We have already converted the expression to an integral or enumeration
1062 // type, when we parsed the switch condition. There are cases where we don't
1063 // have an appropriate type, e.g. a typo-expr Cond was corrected to an
1064 // inappropriate-type expr, we just return an error.
1065 if (!CondExpr->getType()->isIntegralOrEnumerationType())
1066 return StmtError();
1067 if (CondExpr->isKnownToHaveBooleanValue()) {
1068 // switch(bool_expr) {...} is often a programmer error, e.g.
1069 // switch(n && mask) { ... } // Doh - should be "n & mask".
1070 // One can always use an if statement instead of switch(bool_expr).
1071 Diag(SwitchLoc, diag::warn_bool_switch_condition)
1072 << CondExpr->getSourceRange();
1073 }
1074 }
1075
1076 setFunctionHasBranchIntoScope();
1077
1078 auto *SS = SwitchStmt::Create(Context, InitStmt, Cond.get().first, CondExpr,
1079 LParenLoc, RParenLoc);
1080 getCurFunction()->SwitchStack.push_back(
1081 FunctionScopeInfo::SwitchInfo(SS, false));
1082 return SS;
1083 }
1084
AdjustAPSInt(llvm::APSInt & Val,unsigned BitWidth,bool IsSigned)1085 static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) {
1086 Val = Val.extOrTrunc(BitWidth);
1087 Val.setIsSigned(IsSigned);
1088 }
1089
1090 /// Check the specified case value is in range for the given unpromoted switch
1091 /// type.
checkCaseValue(Sema & S,SourceLocation Loc,const llvm::APSInt & Val,unsigned UnpromotedWidth,bool UnpromotedSign)1092 static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val,
1093 unsigned UnpromotedWidth, bool UnpromotedSign) {
1094 // In C++11 onwards, this is checked by the language rules.
1095 if (S.getLangOpts().CPlusPlus11)
1096 return;
1097
1098 // If the case value was signed and negative and the switch expression is
1099 // unsigned, don't bother to warn: this is implementation-defined behavior.
1100 // FIXME: Introduce a second, default-ignored warning for this case?
1101 if (UnpromotedWidth < Val.getBitWidth()) {
1102 llvm::APSInt ConvVal(Val);
1103 AdjustAPSInt(ConvVal, UnpromotedWidth, UnpromotedSign);
1104 AdjustAPSInt(ConvVal, Val.getBitWidth(), Val.isSigned());
1105 // FIXME: Use different diagnostics for overflow in conversion to promoted
1106 // type versus "switch expression cannot have this value". Use proper
1107 // IntRange checking rather than just looking at the unpromoted type here.
1108 if (ConvVal != Val)
1109 S.Diag(Loc, diag::warn_case_value_overflow) << Val.toString(10)
1110 << ConvVal.toString(10);
1111 }
1112 }
1113
1114 typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl*>, 64> EnumValsTy;
1115
1116 /// Returns true if we should emit a diagnostic about this case expression not
1117 /// 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)1118 static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
1119 const EnumDecl *ED,
1120 const Expr *CaseExpr,
1121 EnumValsTy::iterator &EI,
1122 EnumValsTy::iterator &EIEnd,
1123 const llvm::APSInt &Val) {
1124 if (!ED->isClosed())
1125 return false;
1126
1127 if (const DeclRefExpr *DRE =
1128 dyn_cast<DeclRefExpr>(CaseExpr->IgnoreParenImpCasts())) {
1129 if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
1130 QualType VarType = VD->getType();
1131 QualType EnumType = S.Context.getTypeDeclType(ED);
1132 if (VD->hasGlobalStorage() && VarType.isConstQualified() &&
1133 S.Context.hasSameUnqualifiedType(EnumType, VarType))
1134 return false;
1135 }
1136 }
1137
1138 if (ED->hasAttr<FlagEnumAttr>())
1139 return !S.IsValueInFlagEnum(ED, Val, false);
1140
1141 while (EI != EIEnd && EI->first < Val)
1142 EI++;
1143
1144 if (EI != EIEnd && EI->first == Val)
1145 return false;
1146
1147 return true;
1148 }
1149
checkEnumTypesInSwitchStmt(Sema & S,const Expr * Cond,const Expr * Case)1150 static void checkEnumTypesInSwitchStmt(Sema &S, const Expr *Cond,
1151 const Expr *Case) {
1152 QualType CondType = Cond->getType();
1153 QualType CaseType = Case->getType();
1154
1155 const EnumType *CondEnumType = CondType->getAs<EnumType>();
1156 const EnumType *CaseEnumType = CaseType->getAs<EnumType>();
1157 if (!CondEnumType || !CaseEnumType)
1158 return;
1159
1160 // Ignore anonymous enums.
1161 if (!CondEnumType->getDecl()->getIdentifier() &&
1162 !CondEnumType->getDecl()->getTypedefNameForAnonDecl())
1163 return;
1164 if (!CaseEnumType->getDecl()->getIdentifier() &&
1165 !CaseEnumType->getDecl()->getTypedefNameForAnonDecl())
1166 return;
1167
1168 if (S.Context.hasSameUnqualifiedType(CondType, CaseType))
1169 return;
1170
1171 S.Diag(Case->getExprLoc(), diag::warn_comparison_of_mixed_enum_types_switch)
1172 << CondType << CaseType << Cond->getSourceRange()
1173 << Case->getSourceRange();
1174 }
1175
1176 StmtResult
ActOnFinishSwitchStmt(SourceLocation SwitchLoc,Stmt * Switch,Stmt * BodyStmt)1177 Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
1178 Stmt *BodyStmt) {
1179 SwitchStmt *SS = cast<SwitchStmt>(Switch);
1180 bool CaseListIsIncomplete = getCurFunction()->SwitchStack.back().getInt();
1181 assert(SS == getCurFunction()->SwitchStack.back().getPointer() &&
1182 "switch stack missing push/pop!");
1183
1184 getCurFunction()->SwitchStack.pop_back();
1185
1186 if (!BodyStmt) return StmtError();
1187 SS->setBody(BodyStmt, SwitchLoc);
1188
1189 Expr *CondExpr = SS->getCond();
1190 if (!CondExpr) return StmtError();
1191
1192 QualType CondType = CondExpr->getType();
1193
1194 // C++ 6.4.2.p2:
1195 // Integral promotions are performed (on the switch condition).
1196 //
1197 // A case value unrepresentable by the original switch condition
1198 // type (before the promotion) doesn't make sense, even when it can
1199 // be represented by the promoted type. Therefore we need to find
1200 // the pre-promotion type of the switch condition.
1201 const Expr *CondExprBeforePromotion = CondExpr;
1202 QualType CondTypeBeforePromotion =
1203 GetTypeBeforeIntegralPromotion(CondExprBeforePromotion);
1204
1205 // Get the bitwidth of the switched-on value after promotions. We must
1206 // convert the integer case values to this width before comparison.
1207 bool HasDependentValue
1208 = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
1209 unsigned CondWidth = HasDependentValue ? 0 : Context.getIntWidth(CondType);
1210 bool CondIsSigned = CondType->isSignedIntegerOrEnumerationType();
1211
1212 // Get the width and signedness that the condition might actually have, for
1213 // warning purposes.
1214 // FIXME: Grab an IntRange for the condition rather than using the unpromoted
1215 // type.
1216 unsigned CondWidthBeforePromotion
1217 = HasDependentValue ? 0 : Context.getIntWidth(CondTypeBeforePromotion);
1218 bool CondIsSignedBeforePromotion
1219 = CondTypeBeforePromotion->isSignedIntegerOrEnumerationType();
1220
1221 // Accumulate all of the case values in a vector so that we can sort them
1222 // and detect duplicates. This vector contains the APInt for the case after
1223 // it has been converted to the condition type.
1224 typedef SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
1225 CaseValsTy CaseVals;
1226
1227 // Keep track of any GNU case ranges we see. The APSInt is the low value.
1228 typedef std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRangesTy;
1229 CaseRangesTy CaseRanges;
1230
1231 DefaultStmt *TheDefaultStmt = nullptr;
1232
1233 bool CaseListIsErroneous = false;
1234
1235 for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
1236 SC = SC->getNextSwitchCase()) {
1237
1238 if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
1239 if (TheDefaultStmt) {
1240 Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
1241 Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
1242
1243 // FIXME: Remove the default statement from the switch block so that
1244 // we'll return a valid AST. This requires recursing down the AST and
1245 // finding it, not something we are set up to do right now. For now,
1246 // just lop the entire switch stmt out of the AST.
1247 CaseListIsErroneous = true;
1248 }
1249 TheDefaultStmt = DS;
1250
1251 } else {
1252 CaseStmt *CS = cast<CaseStmt>(SC);
1253
1254 Expr *Lo = CS->getLHS();
1255
1256 if (Lo->isValueDependent()) {
1257 HasDependentValue = true;
1258 break;
1259 }
1260
1261 // We already verified that the expression has a constant value;
1262 // get that value (prior to conversions).
1263 const Expr *LoBeforePromotion = Lo;
1264 GetTypeBeforeIntegralPromotion(LoBeforePromotion);
1265 llvm::APSInt LoVal = LoBeforePromotion->EvaluateKnownConstInt(Context);
1266
1267 // Check the unconverted value is within the range of possible values of
1268 // the switch expression.
1269 checkCaseValue(*this, Lo->getBeginLoc(), LoVal, CondWidthBeforePromotion,
1270 CondIsSignedBeforePromotion);
1271
1272 // FIXME: This duplicates the check performed for warn_not_in_enum below.
1273 checkEnumTypesInSwitchStmt(*this, CondExprBeforePromotion,
1274 LoBeforePromotion);
1275
1276 // Convert the value to the same width/sign as the condition.
1277 AdjustAPSInt(LoVal, CondWidth, CondIsSigned);
1278
1279 // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
1280 if (CS->getRHS()) {
1281 if (CS->getRHS()->isValueDependent()) {
1282 HasDependentValue = true;
1283 break;
1284 }
1285 CaseRanges.push_back(std::make_pair(LoVal, CS));
1286 } else
1287 CaseVals.push_back(std::make_pair(LoVal, CS));
1288 }
1289 }
1290
1291 if (!HasDependentValue) {
1292 // If we don't have a default statement, check whether the
1293 // condition is constant.
1294 llvm::APSInt ConstantCondValue;
1295 bool HasConstantCond = false;
1296 if (!TheDefaultStmt) {
1297 Expr::EvalResult Result;
1298 HasConstantCond = CondExpr->EvaluateAsInt(Result, Context,
1299 Expr::SE_AllowSideEffects);
1300 if (Result.Val.isInt())
1301 ConstantCondValue = Result.Val.getInt();
1302 assert(!HasConstantCond ||
1303 (ConstantCondValue.getBitWidth() == CondWidth &&
1304 ConstantCondValue.isSigned() == CondIsSigned));
1305 }
1306 bool ShouldCheckConstantCond = HasConstantCond;
1307
1308 // Sort all the scalar case values so we can easily detect duplicates.
1309 llvm::stable_sort(CaseVals, CmpCaseVals);
1310
1311 if (!CaseVals.empty()) {
1312 for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) {
1313 if (ShouldCheckConstantCond &&
1314 CaseVals[i].first == ConstantCondValue)
1315 ShouldCheckConstantCond = false;
1316
1317 if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) {
1318 // If we have a duplicate, report it.
1319 // First, determine if either case value has a name
1320 StringRef PrevString, CurrString;
1321 Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts();
1322 Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts();
1323 if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(PrevCase)) {
1324 PrevString = DeclRef->getDecl()->getName();
1325 }
1326 if (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(CurrCase)) {
1327 CurrString = DeclRef->getDecl()->getName();
1328 }
1329 SmallString<16> CaseValStr;
1330 CaseVals[i-1].first.toString(CaseValStr);
1331
1332 if (PrevString == CurrString)
1333 Diag(CaseVals[i].second->getLHS()->getBeginLoc(),
1334 diag::err_duplicate_case)
1335 << (PrevString.empty() ? StringRef(CaseValStr) : PrevString);
1336 else
1337 Diag(CaseVals[i].second->getLHS()->getBeginLoc(),
1338 diag::err_duplicate_case_differing_expr)
1339 << (PrevString.empty() ? StringRef(CaseValStr) : PrevString)
1340 << (CurrString.empty() ? StringRef(CaseValStr) : CurrString)
1341 << CaseValStr;
1342
1343 Diag(CaseVals[i - 1].second->getLHS()->getBeginLoc(),
1344 diag::note_duplicate_case_prev);
1345 // FIXME: We really want to remove the bogus case stmt from the
1346 // substmt, but we have no way to do this right now.
1347 CaseListIsErroneous = true;
1348 }
1349 }
1350 }
1351
1352 // Detect duplicate case ranges, which usually don't exist at all in
1353 // the first place.
1354 if (!CaseRanges.empty()) {
1355 // Sort all the case ranges by their low value so we can easily detect
1356 // overlaps between ranges.
1357 llvm::stable_sort(CaseRanges);
1358
1359 // Scan the ranges, computing the high values and removing empty ranges.
1360 std::vector<llvm::APSInt> HiVals;
1361 for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1362 llvm::APSInt &LoVal = CaseRanges[i].first;
1363 CaseStmt *CR = CaseRanges[i].second;
1364 Expr *Hi = CR->getRHS();
1365
1366 const Expr *HiBeforePromotion = Hi;
1367 GetTypeBeforeIntegralPromotion(HiBeforePromotion);
1368 llvm::APSInt HiVal = HiBeforePromotion->EvaluateKnownConstInt(Context);
1369
1370 // Check the unconverted value is within the range of possible values of
1371 // the switch expression.
1372 checkCaseValue(*this, Hi->getBeginLoc(), HiVal,
1373 CondWidthBeforePromotion, CondIsSignedBeforePromotion);
1374
1375 // Convert the value to the same width/sign as the condition.
1376 AdjustAPSInt(HiVal, CondWidth, CondIsSigned);
1377
1378 // If the low value is bigger than the high value, the case is empty.
1379 if (LoVal > HiVal) {
1380 Diag(CR->getLHS()->getBeginLoc(), diag::warn_case_empty_range)
1381 << SourceRange(CR->getLHS()->getBeginLoc(), Hi->getEndLoc());
1382 CaseRanges.erase(CaseRanges.begin()+i);
1383 --i;
1384 --e;
1385 continue;
1386 }
1387
1388 if (ShouldCheckConstantCond &&
1389 LoVal <= ConstantCondValue &&
1390 ConstantCondValue <= HiVal)
1391 ShouldCheckConstantCond = false;
1392
1393 HiVals.push_back(HiVal);
1394 }
1395
1396 // Rescan the ranges, looking for overlap with singleton values and other
1397 // ranges. Since the range list is sorted, we only need to compare case
1398 // ranges with their neighbors.
1399 for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
1400 llvm::APSInt &CRLo = CaseRanges[i].first;
1401 llvm::APSInt &CRHi = HiVals[i];
1402 CaseStmt *CR = CaseRanges[i].second;
1403
1404 // Check to see whether the case range overlaps with any
1405 // singleton cases.
1406 CaseStmt *OverlapStmt = nullptr;
1407 llvm::APSInt OverlapVal(32);
1408
1409 // Find the smallest value >= the lower bound. If I is in the
1410 // case range, then we have overlap.
1411 CaseValsTy::iterator I =
1412 llvm::lower_bound(CaseVals, CRLo, CaseCompareFunctor());
1413 if (I != CaseVals.end() && I->first < CRHi) {
1414 OverlapVal = I->first; // Found overlap with scalar.
1415 OverlapStmt = I->second;
1416 }
1417
1418 // Find the smallest value bigger than the upper bound.
1419 I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
1420 if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
1421 OverlapVal = (I-1)->first; // Found overlap with scalar.
1422 OverlapStmt = (I-1)->second;
1423 }
1424
1425 // Check to see if this case stmt overlaps with the subsequent
1426 // case range.
1427 if (i && CRLo <= HiVals[i-1]) {
1428 OverlapVal = HiVals[i-1]; // Found overlap with range.
1429 OverlapStmt = CaseRanges[i-1].second;
1430 }
1431
1432 if (OverlapStmt) {
1433 // If we have a duplicate, report it.
1434 Diag(CR->getLHS()->getBeginLoc(), diag::err_duplicate_case)
1435 << OverlapVal.toString(10);
1436 Diag(OverlapStmt->getLHS()->getBeginLoc(),
1437 diag::note_duplicate_case_prev);
1438 // FIXME: We really want to remove the bogus case stmt from the
1439 // substmt, but we have no way to do this right now.
1440 CaseListIsErroneous = true;
1441 }
1442 }
1443 }
1444
1445 // Complain if we have a constant condition and we didn't find a match.
1446 if (!CaseListIsErroneous && !CaseListIsIncomplete &&
1447 ShouldCheckConstantCond) {
1448 // TODO: it would be nice if we printed enums as enums, chars as
1449 // chars, etc.
1450 Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition)
1451 << ConstantCondValue.toString(10)
1452 << CondExpr->getSourceRange();
1453 }
1454
1455 // Check to see if switch is over an Enum and handles all of its
1456 // values. We only issue a warning if there is not 'default:', but
1457 // we still do the analysis to preserve this information in the AST
1458 // (which can be used by flow-based analyes).
1459 //
1460 const EnumType *ET = CondTypeBeforePromotion->getAs<EnumType>();
1461
1462 // If switch has default case, then ignore it.
1463 if (!CaseListIsErroneous && !CaseListIsIncomplete && !HasConstantCond &&
1464 ET && ET->getDecl()->isCompleteDefinition()) {
1465 const EnumDecl *ED = ET->getDecl();
1466 EnumValsTy EnumVals;
1467
1468 // Gather all enum values, set their type and sort them,
1469 // allowing easier comparison with CaseVals.
1470 for (auto *EDI : ED->enumerators()) {
1471 llvm::APSInt Val = EDI->getInitVal();
1472 AdjustAPSInt(Val, CondWidth, CondIsSigned);
1473 EnumVals.push_back(std::make_pair(Val, EDI));
1474 }
1475 llvm::stable_sort(EnumVals, CmpEnumVals);
1476 auto EI = EnumVals.begin(), EIEnd =
1477 std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1478
1479 // See which case values aren't in enum.
1480 for (CaseValsTy::const_iterator CI = CaseVals.begin();
1481 CI != CaseVals.end(); CI++) {
1482 Expr *CaseExpr = CI->second->getLHS();
1483 if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1484 CI->first))
1485 Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1486 << CondTypeBeforePromotion;
1487 }
1488
1489 // See which of case ranges aren't in enum
1490 EI = EnumVals.begin();
1491 for (CaseRangesTy::const_iterator RI = CaseRanges.begin();
1492 RI != CaseRanges.end(); RI++) {
1493 Expr *CaseExpr = RI->second->getLHS();
1494 if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1495 RI->first))
1496 Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1497 << CondTypeBeforePromotion;
1498
1499 llvm::APSInt Hi =
1500 RI->second->getRHS()->EvaluateKnownConstInt(Context);
1501 AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1502
1503 CaseExpr = RI->second->getRHS();
1504 if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd,
1505 Hi))
1506 Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum)
1507 << CondTypeBeforePromotion;
1508 }
1509
1510 // Check which enum vals aren't in switch
1511 auto CI = CaseVals.begin();
1512 auto RI = CaseRanges.begin();
1513 bool hasCasesNotInSwitch = false;
1514
1515 SmallVector<DeclarationName,8> UnhandledNames;
1516
1517 for (EI = EnumVals.begin(); EI != EIEnd; EI++) {
1518 // Don't warn about omitted unavailable EnumConstantDecls.
1519 switch (EI->second->getAvailability()) {
1520 case AR_Deprecated:
1521 // Omitting a deprecated constant is ok; it should never materialize.
1522 case AR_Unavailable:
1523 continue;
1524
1525 case AR_NotYetIntroduced:
1526 // Partially available enum constants should be present. Note that we
1527 // suppress -Wunguarded-availability diagnostics for such uses.
1528 case AR_Available:
1529 break;
1530 }
1531
1532 if (EI->second->hasAttr<UnusedAttr>())
1533 continue;
1534
1535 // Drop unneeded case values
1536 while (CI != CaseVals.end() && CI->first < EI->first)
1537 CI++;
1538
1539 if (CI != CaseVals.end() && CI->first == EI->first)
1540 continue;
1541
1542 // Drop unneeded case ranges
1543 for (; RI != CaseRanges.end(); RI++) {
1544 llvm::APSInt Hi =
1545 RI->second->getRHS()->EvaluateKnownConstInt(Context);
1546 AdjustAPSInt(Hi, CondWidth, CondIsSigned);
1547 if (EI->first <= Hi)
1548 break;
1549 }
1550
1551 if (RI == CaseRanges.end() || EI->first < RI->first) {
1552 hasCasesNotInSwitch = true;
1553 UnhandledNames.push_back(EI->second->getDeclName());
1554 }
1555 }
1556
1557 if (TheDefaultStmt && UnhandledNames.empty() && ED->isClosedNonFlag())
1558 Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
1559
1560 // Produce a nice diagnostic if multiple values aren't handled.
1561 if (!UnhandledNames.empty()) {
1562 auto DB = Diag(CondExpr->getExprLoc(), TheDefaultStmt
1563 ? diag::warn_def_missing_case
1564 : diag::warn_missing_case)
1565 << (int)UnhandledNames.size();
1566
1567 for (size_t I = 0, E = std::min(UnhandledNames.size(), (size_t)3);
1568 I != E; ++I)
1569 DB << UnhandledNames[I];
1570 }
1571
1572 if (!hasCasesNotInSwitch)
1573 SS->setAllEnumCasesCovered();
1574 }
1575 }
1576
1577 if (BodyStmt)
1578 DiagnoseEmptyStmtBody(CondExpr->getEndLoc(), BodyStmt,
1579 diag::warn_empty_switch_body);
1580
1581 // FIXME: If the case list was broken is some way, we don't have a good system
1582 // to patch it up. Instead, just return the whole substmt as broken.
1583 if (CaseListIsErroneous)
1584 return StmtError();
1585
1586 return SS;
1587 }
1588
1589 void
DiagnoseAssignmentEnum(QualType DstType,QualType SrcType,Expr * SrcExpr)1590 Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
1591 Expr *SrcExpr) {
1592 if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc()))
1593 return;
1594
1595 if (const EnumType *ET = DstType->getAs<EnumType>())
1596 if (!Context.hasSameUnqualifiedType(SrcType, DstType) &&
1597 SrcType->isIntegerType()) {
1598 if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() &&
1599 SrcExpr->isIntegerConstantExpr(Context)) {
1600 // Get the bitwidth of the enum value before promotions.
1601 unsigned DstWidth = Context.getIntWidth(DstType);
1602 bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType();
1603
1604 llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context);
1605 AdjustAPSInt(RhsVal, DstWidth, DstIsSigned);
1606 const EnumDecl *ED = ET->getDecl();
1607
1608 if (!ED->isClosed())
1609 return;
1610
1611 if (ED->hasAttr<FlagEnumAttr>()) {
1612 if (!IsValueInFlagEnum(ED, RhsVal, true))
1613 Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1614 << DstType.getUnqualifiedType();
1615 } else {
1616 typedef SmallVector<std::pair<llvm::APSInt, EnumConstantDecl *>, 64>
1617 EnumValsTy;
1618 EnumValsTy EnumVals;
1619
1620 // Gather all enum values, set their type and sort them,
1621 // allowing easier comparison with rhs constant.
1622 for (auto *EDI : ED->enumerators()) {
1623 llvm::APSInt Val = EDI->getInitVal();
1624 AdjustAPSInt(Val, DstWidth, DstIsSigned);
1625 EnumVals.push_back(std::make_pair(Val, EDI));
1626 }
1627 if (EnumVals.empty())
1628 return;
1629 llvm::stable_sort(EnumVals, CmpEnumVals);
1630 EnumValsTy::iterator EIend =
1631 std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals);
1632
1633 // See which values aren't in the enum.
1634 EnumValsTy::const_iterator EI = EnumVals.begin();
1635 while (EI != EIend && EI->first < RhsVal)
1636 EI++;
1637 if (EI == EIend || EI->first != RhsVal) {
1638 Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
1639 << DstType.getUnqualifiedType();
1640 }
1641 }
1642 }
1643 }
1644 }
1645
ActOnWhileStmt(SourceLocation WhileLoc,SourceLocation LParenLoc,ConditionResult Cond,SourceLocation RParenLoc,Stmt * Body)1646 StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc,
1647 SourceLocation LParenLoc, ConditionResult Cond,
1648 SourceLocation RParenLoc, Stmt *Body) {
1649 if (Cond.isInvalid())
1650 return StmtError();
1651
1652 auto CondVal = Cond.get();
1653 CheckBreakContinueBinding(CondVal.second);
1654
1655 if (CondVal.second &&
1656 !Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc()))
1657 CommaVisitor(*this).Visit(CondVal.second);
1658
1659 if (isa<NullStmt>(Body))
1660 getCurCompoundScope().setHasEmptyLoopBodies();
1661
1662 return WhileStmt::Create(Context, CondVal.first, CondVal.second, Body,
1663 WhileLoc, LParenLoc, RParenLoc);
1664 }
1665
1666 StmtResult
ActOnDoStmt(SourceLocation DoLoc,Stmt * Body,SourceLocation WhileLoc,SourceLocation CondLParen,Expr * Cond,SourceLocation CondRParen)1667 Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
1668 SourceLocation WhileLoc, SourceLocation CondLParen,
1669 Expr *Cond, SourceLocation CondRParen) {
1670 assert(Cond && "ActOnDoStmt(): missing expression");
1671
1672 CheckBreakContinueBinding(Cond);
1673 ExprResult CondResult = CheckBooleanCondition(DoLoc, Cond);
1674 if (CondResult.isInvalid())
1675 return StmtError();
1676 Cond = CondResult.get();
1677
1678 CondResult = ActOnFinishFullExpr(Cond, DoLoc, /*DiscardedValue*/ false);
1679 if (CondResult.isInvalid())
1680 return StmtError();
1681 Cond = CondResult.get();
1682
1683 // Only call the CommaVisitor for C89 due to differences in scope flags.
1684 if (Cond && !getLangOpts().C99 && !getLangOpts().CPlusPlus &&
1685 !Diags.isIgnored(diag::warn_comma_operator, Cond->getExprLoc()))
1686 CommaVisitor(*this).Visit(Cond);
1687
1688 return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen);
1689 }
1690
1691 namespace {
1692 // Use SetVector since the diagnostic cares about the ordering of the Decl's.
1693 using DeclSetVector =
1694 llvm::SetVector<VarDecl *, llvm::SmallVector<VarDecl *, 8>,
1695 llvm::SmallPtrSet<VarDecl *, 8>>;
1696
1697 // This visitor will traverse a conditional statement and store all
1698 // the evaluated decls into a vector. Simple is set to true if none
1699 // of the excluded constructs are used.
1700 class DeclExtractor : public EvaluatedExprVisitor<DeclExtractor> {
1701 DeclSetVector &Decls;
1702 SmallVectorImpl<SourceRange> &Ranges;
1703 bool Simple;
1704 public:
1705 typedef EvaluatedExprVisitor<DeclExtractor> Inherited;
1706
DeclExtractor(Sema & S,DeclSetVector & Decls,SmallVectorImpl<SourceRange> & Ranges)1707 DeclExtractor(Sema &S, DeclSetVector &Decls,
1708 SmallVectorImpl<SourceRange> &Ranges) :
1709 Inherited(S.Context),
1710 Decls(Decls),
1711 Ranges(Ranges),
1712 Simple(true) {}
1713
isSimple()1714 bool isSimple() { return Simple; }
1715
1716 // Replaces the method in EvaluatedExprVisitor.
VisitMemberExpr(MemberExpr * E)1717 void VisitMemberExpr(MemberExpr* E) {
1718 Simple = false;
1719 }
1720
1721 // Any Stmt not explicitly listed will cause the condition to be marked
1722 // complex.
VisitStmt(Stmt * S)1723 void VisitStmt(Stmt *S) { Simple = false; }
1724
VisitBinaryOperator(BinaryOperator * E)1725 void VisitBinaryOperator(BinaryOperator *E) {
1726 Visit(E->getLHS());
1727 Visit(E->getRHS());
1728 }
1729
VisitCastExpr(CastExpr * E)1730 void VisitCastExpr(CastExpr *E) {
1731 Visit(E->getSubExpr());
1732 }
1733
VisitUnaryOperator(UnaryOperator * E)1734 void VisitUnaryOperator(UnaryOperator *E) {
1735 // Skip checking conditionals with derefernces.
1736 if (E->getOpcode() == UO_Deref)
1737 Simple = false;
1738 else
1739 Visit(E->getSubExpr());
1740 }
1741
VisitConditionalOperator(ConditionalOperator * E)1742 void VisitConditionalOperator(ConditionalOperator *E) {
1743 Visit(E->getCond());
1744 Visit(E->getTrueExpr());
1745 Visit(E->getFalseExpr());
1746 }
1747
VisitParenExpr(ParenExpr * E)1748 void VisitParenExpr(ParenExpr *E) {
1749 Visit(E->getSubExpr());
1750 }
1751
VisitBinaryConditionalOperator(BinaryConditionalOperator * E)1752 void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
1753 Visit(E->getOpaqueValue()->getSourceExpr());
1754 Visit(E->getFalseExpr());
1755 }
1756
VisitIntegerLiteral(IntegerLiteral * E)1757 void VisitIntegerLiteral(IntegerLiteral *E) { }
VisitFloatingLiteral(FloatingLiteral * E)1758 void VisitFloatingLiteral(FloatingLiteral *E) { }
VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr * E)1759 void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { }
VisitCharacterLiteral(CharacterLiteral * E)1760 void VisitCharacterLiteral(CharacterLiteral *E) { }
VisitGNUNullExpr(GNUNullExpr * E)1761 void VisitGNUNullExpr(GNUNullExpr *E) { }
VisitImaginaryLiteral(ImaginaryLiteral * E)1762 void VisitImaginaryLiteral(ImaginaryLiteral *E) { }
1763
VisitDeclRefExpr(DeclRefExpr * E)1764 void VisitDeclRefExpr(DeclRefExpr *E) {
1765 VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
1766 if (!VD) {
1767 // Don't allow unhandled Decl types.
1768 Simple = false;
1769 return;
1770 }
1771
1772 Ranges.push_back(E->getSourceRange());
1773
1774 Decls.insert(VD);
1775 }
1776
1777 }; // end class DeclExtractor
1778
1779 // DeclMatcher checks to see if the decls are used in a non-evaluated
1780 // context.
1781 class DeclMatcher : public EvaluatedExprVisitor<DeclMatcher> {
1782 DeclSetVector &Decls;
1783 bool FoundDecl;
1784
1785 public:
1786 typedef EvaluatedExprVisitor<DeclMatcher> Inherited;
1787
DeclMatcher(Sema & S,DeclSetVector & Decls,Stmt * Statement)1788 DeclMatcher(Sema &S, DeclSetVector &Decls, Stmt *Statement) :
1789 Inherited(S.Context), Decls(Decls), FoundDecl(false) {
1790 if (!Statement) return;
1791
1792 Visit(Statement);
1793 }
1794
VisitReturnStmt(ReturnStmt * S)1795 void VisitReturnStmt(ReturnStmt *S) {
1796 FoundDecl = true;
1797 }
1798
VisitBreakStmt(BreakStmt * S)1799 void VisitBreakStmt(BreakStmt *S) {
1800 FoundDecl = true;
1801 }
1802
VisitGotoStmt(GotoStmt * S)1803 void VisitGotoStmt(GotoStmt *S) {
1804 FoundDecl = true;
1805 }
1806
VisitCastExpr(CastExpr * E)1807 void VisitCastExpr(CastExpr *E) {
1808 if (E->getCastKind() == CK_LValueToRValue)
1809 CheckLValueToRValueCast(E->getSubExpr());
1810 else
1811 Visit(E->getSubExpr());
1812 }
1813
CheckLValueToRValueCast(Expr * E)1814 void CheckLValueToRValueCast(Expr *E) {
1815 E = E->IgnoreParenImpCasts();
1816
1817 if (isa<DeclRefExpr>(E)) {
1818 return;
1819 }
1820
1821 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
1822 Visit(CO->getCond());
1823 CheckLValueToRValueCast(CO->getTrueExpr());
1824 CheckLValueToRValueCast(CO->getFalseExpr());
1825 return;
1826 }
1827
1828 if (BinaryConditionalOperator *BCO =
1829 dyn_cast<BinaryConditionalOperator>(E)) {
1830 CheckLValueToRValueCast(BCO->getOpaqueValue()->getSourceExpr());
1831 CheckLValueToRValueCast(BCO->getFalseExpr());
1832 return;
1833 }
1834
1835 Visit(E);
1836 }
1837
VisitDeclRefExpr(DeclRefExpr * E)1838 void VisitDeclRefExpr(DeclRefExpr *E) {
1839 if (VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
1840 if (Decls.count(VD))
1841 FoundDecl = true;
1842 }
1843
VisitPseudoObjectExpr(PseudoObjectExpr * POE)1844 void VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
1845 // Only need to visit the semantics for POE.
1846 // SyntaticForm doesn't really use the Decal.
1847 for (auto *S : POE->semantics()) {
1848 if (auto *OVE = dyn_cast<OpaqueValueExpr>(S))
1849 // Look past the OVE into the expression it binds.
1850 Visit(OVE->getSourceExpr());
1851 else
1852 Visit(S);
1853 }
1854 }
1855
FoundDeclInUse()1856 bool FoundDeclInUse() { return FoundDecl; }
1857
1858 }; // end class DeclMatcher
1859
CheckForLoopConditionalStatement(Sema & S,Expr * Second,Expr * Third,Stmt * Body)1860 void CheckForLoopConditionalStatement(Sema &S, Expr *Second,
1861 Expr *Third, Stmt *Body) {
1862 // Condition is empty
1863 if (!Second) return;
1864
1865 if (S.Diags.isIgnored(diag::warn_variables_not_in_loop_body,
1866 Second->getBeginLoc()))
1867 return;
1868
1869 PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body);
1870 DeclSetVector Decls;
1871 SmallVector<SourceRange, 10> Ranges;
1872 DeclExtractor DE(S, Decls, Ranges);
1873 DE.Visit(Second);
1874
1875 // Don't analyze complex conditionals.
1876 if (!DE.isSimple()) return;
1877
1878 // No decls found.
1879 if (Decls.size() == 0) return;
1880
1881 // Don't warn on volatile, static, or global variables.
1882 for (auto *VD : Decls)
1883 if (VD->getType().isVolatileQualified() || VD->hasGlobalStorage())
1884 return;
1885
1886 if (DeclMatcher(S, Decls, Second).FoundDeclInUse() ||
1887 DeclMatcher(S, Decls, Third).FoundDeclInUse() ||
1888 DeclMatcher(S, Decls, Body).FoundDeclInUse())
1889 return;
1890
1891 // Load decl names into diagnostic.
1892 if (Decls.size() > 4) {
1893 PDiag << 0;
1894 } else {
1895 PDiag << (unsigned)Decls.size();
1896 for (auto *VD : Decls)
1897 PDiag << VD->getDeclName();
1898 }
1899
1900 for (auto Range : Ranges)
1901 PDiag << Range;
1902
1903 S.Diag(Ranges.begin()->getBegin(), PDiag);
1904 }
1905
1906 // If Statement is an incemement or decrement, return true and sets the
1907 // variables Increment and DRE.
ProcessIterationStmt(Sema & S,Stmt * Statement,bool & Increment,DeclRefExpr * & DRE)1908 bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment,
1909 DeclRefExpr *&DRE) {
1910 if (auto Cleanups = dyn_cast<ExprWithCleanups>(Statement))
1911 if (!Cleanups->cleanupsHaveSideEffects())
1912 Statement = Cleanups->getSubExpr();
1913
1914 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(Statement)) {
1915 switch (UO->getOpcode()) {
1916 default: return false;
1917 case UO_PostInc:
1918 case UO_PreInc:
1919 Increment = true;
1920 break;
1921 case UO_PostDec:
1922 case UO_PreDec:
1923 Increment = false;
1924 break;
1925 }
1926 DRE = dyn_cast<DeclRefExpr>(UO->getSubExpr());
1927 return DRE;
1928 }
1929
1930 if (CXXOperatorCallExpr *Call = dyn_cast<CXXOperatorCallExpr>(Statement)) {
1931 FunctionDecl *FD = Call->getDirectCallee();
1932 if (!FD || !FD->isOverloadedOperator()) return false;
1933 switch (FD->getOverloadedOperator()) {
1934 default: return false;
1935 case OO_PlusPlus:
1936 Increment = true;
1937 break;
1938 case OO_MinusMinus:
1939 Increment = false;
1940 break;
1941 }
1942 DRE = dyn_cast<DeclRefExpr>(Call->getArg(0));
1943 return DRE;
1944 }
1945
1946 return false;
1947 }
1948
1949 // A visitor to determine if a continue or break statement is a
1950 // subexpression.
1951 class BreakContinueFinder : public ConstEvaluatedExprVisitor<BreakContinueFinder> {
1952 SourceLocation BreakLoc;
1953 SourceLocation ContinueLoc;
1954 bool InSwitch = false;
1955
1956 public:
BreakContinueFinder(Sema & S,const Stmt * Body)1957 BreakContinueFinder(Sema &S, const Stmt* Body) :
1958 Inherited(S.Context) {
1959 Visit(Body);
1960 }
1961
1962 typedef ConstEvaluatedExprVisitor<BreakContinueFinder> Inherited;
1963
VisitContinueStmt(const ContinueStmt * E)1964 void VisitContinueStmt(const ContinueStmt* E) {
1965 ContinueLoc = E->getContinueLoc();
1966 }
1967
VisitBreakStmt(const BreakStmt * E)1968 void VisitBreakStmt(const BreakStmt* E) {
1969 if (!InSwitch)
1970 BreakLoc = E->getBreakLoc();
1971 }
1972
VisitSwitchStmt(const SwitchStmt * S)1973 void VisitSwitchStmt(const SwitchStmt* S) {
1974 if (const Stmt *Init = S->getInit())
1975 Visit(Init);
1976 if (const Stmt *CondVar = S->getConditionVariableDeclStmt())
1977 Visit(CondVar);
1978 if (const Stmt *Cond = S->getCond())
1979 Visit(Cond);
1980
1981 // Don't return break statements from the body of a switch.
1982 InSwitch = true;
1983 if (const Stmt *Body = S->getBody())
1984 Visit(Body);
1985 InSwitch = false;
1986 }
1987
VisitForStmt(const ForStmt * S)1988 void VisitForStmt(const ForStmt *S) {
1989 // Only visit the init statement of a for loop; the body
1990 // has a different break/continue scope.
1991 if (const Stmt *Init = S->getInit())
1992 Visit(Init);
1993 }
1994
VisitWhileStmt(const WhileStmt *)1995 void VisitWhileStmt(const WhileStmt *) {
1996 // Do nothing; the children of a while loop have a different
1997 // break/continue scope.
1998 }
1999
VisitDoStmt(const DoStmt *)2000 void VisitDoStmt(const DoStmt *) {
2001 // Do nothing; the children of a while loop have a different
2002 // break/continue scope.
2003 }
2004
VisitCXXForRangeStmt(const CXXForRangeStmt * S)2005 void VisitCXXForRangeStmt(const CXXForRangeStmt *S) {
2006 // Only visit the initialization of a for loop; the body
2007 // has a different break/continue scope.
2008 if (const Stmt *Init = S->getInit())
2009 Visit(Init);
2010 if (const Stmt *Range = S->getRangeStmt())
2011 Visit(Range);
2012 if (const Stmt *Begin = S->getBeginStmt())
2013 Visit(Begin);
2014 if (const Stmt *End = S->getEndStmt())
2015 Visit(End);
2016 }
2017
VisitObjCForCollectionStmt(const ObjCForCollectionStmt * S)2018 void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S) {
2019 // Only visit the initialization of a for loop; the body
2020 // has a different break/continue scope.
2021 if (const Stmt *Element = S->getElement())
2022 Visit(Element);
2023 if (const Stmt *Collection = S->getCollection())
2024 Visit(Collection);
2025 }
2026
ContinueFound()2027 bool ContinueFound() { return ContinueLoc.isValid(); }
BreakFound()2028 bool BreakFound() { return BreakLoc.isValid(); }
GetContinueLoc()2029 SourceLocation GetContinueLoc() { return ContinueLoc; }
GetBreakLoc()2030 SourceLocation GetBreakLoc() { return BreakLoc; }
2031
2032 }; // end class BreakContinueFinder
2033
2034 // Emit a warning when a loop increment/decrement appears twice per loop
2035 // iteration. The conditions which trigger this warning are:
2036 // 1) The last statement in the loop body and the third expression in the
2037 // for loop are both increment or both decrement of the same variable
2038 // 2) No continue statements in the loop body.
CheckForRedundantIteration(Sema & S,Expr * Third,Stmt * Body)2039 void CheckForRedundantIteration(Sema &S, Expr *Third, Stmt *Body) {
2040 // Return when there is nothing to check.
2041 if (!Body || !Third) return;
2042
2043 if (S.Diags.isIgnored(diag::warn_redundant_loop_iteration,
2044 Third->getBeginLoc()))
2045 return;
2046
2047 // Get the last statement from the loop body.
2048 CompoundStmt *CS = dyn_cast<CompoundStmt>(Body);
2049 if (!CS || CS->body_empty()) return;
2050 Stmt *LastStmt = CS->body_back();
2051 if (!LastStmt) return;
2052
2053 bool LoopIncrement, LastIncrement;
2054 DeclRefExpr *LoopDRE, *LastDRE;
2055
2056 if (!ProcessIterationStmt(S, Third, LoopIncrement, LoopDRE)) return;
2057 if (!ProcessIterationStmt(S, LastStmt, LastIncrement, LastDRE)) return;
2058
2059 // Check that the two statements are both increments or both decrements
2060 // on the same variable.
2061 if (LoopIncrement != LastIncrement ||
2062 LoopDRE->getDecl() != LastDRE->getDecl()) return;
2063
2064 if (BreakContinueFinder(S, Body).ContinueFound()) return;
2065
2066 S.Diag(LastDRE->getLocation(), diag::warn_redundant_loop_iteration)
2067 << LastDRE->getDecl() << LastIncrement;
2068 S.Diag(LoopDRE->getLocation(), diag::note_loop_iteration_here)
2069 << LoopIncrement;
2070 }
2071
2072 } // end namespace
2073
2074
CheckBreakContinueBinding(Expr * E)2075 void Sema::CheckBreakContinueBinding(Expr *E) {
2076 if (!E || getLangOpts().CPlusPlus)
2077 return;
2078 BreakContinueFinder BCFinder(*this, E);
2079 Scope *BreakParent = CurScope->getBreakParent();
2080 if (BCFinder.BreakFound() && BreakParent) {
2081 if (BreakParent->getFlags() & Scope::SwitchScope) {
2082 Diag(BCFinder.GetBreakLoc(), diag::warn_break_binds_to_switch);
2083 } else {
2084 Diag(BCFinder.GetBreakLoc(), diag::warn_loop_ctrl_binds_to_inner)
2085 << "break";
2086 }
2087 } else if (BCFinder.ContinueFound() && CurScope->getContinueParent()) {
2088 Diag(BCFinder.GetContinueLoc(), diag::warn_loop_ctrl_binds_to_inner)
2089 << "continue";
2090 }
2091 }
2092
ActOnForStmt(SourceLocation ForLoc,SourceLocation LParenLoc,Stmt * First,ConditionResult Second,FullExprArg third,SourceLocation RParenLoc,Stmt * Body)2093 StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
2094 Stmt *First, ConditionResult Second,
2095 FullExprArg third, SourceLocation RParenLoc,
2096 Stmt *Body) {
2097 if (Second.isInvalid())
2098 return StmtError();
2099
2100 if (!getLangOpts().CPlusPlus) {
2101 if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
2102 // C99 6.8.5p3: The declaration part of a 'for' statement shall only
2103 // declare identifiers for objects having storage class 'auto' or
2104 // 'register'.
2105 const Decl *NonVarSeen = nullptr;
2106 bool VarDeclSeen = false;
2107 for (auto *DI : DS->decls()) {
2108 if (VarDecl *VD = dyn_cast<VarDecl>(DI)) {
2109 VarDeclSeen = true;
2110 if (VD->isLocalVarDecl() && !VD->hasLocalStorage()) {
2111 Diag(DI->getLocation(), diag::err_non_local_variable_decl_in_for);
2112 DI->setInvalidDecl();
2113 }
2114 } else if (!NonVarSeen) {
2115 // Keep track of the first non-variable declaration we saw so that
2116 // we can diagnose if we don't see any variable declarations. This
2117 // covers a case like declaring a typedef, function, or structure
2118 // type rather than a variable.
2119 NonVarSeen = DI;
2120 }
2121 }
2122 // Diagnose if we saw a non-variable declaration but no variable
2123 // declarations.
2124 if (NonVarSeen && !VarDeclSeen)
2125 Diag(NonVarSeen->getLocation(), diag::err_non_variable_decl_in_for);
2126 }
2127 }
2128
2129 CheckBreakContinueBinding(Second.get().second);
2130 CheckBreakContinueBinding(third.get());
2131
2132 if (!Second.get().first)
2133 CheckForLoopConditionalStatement(*this, Second.get().second, third.get(),
2134 Body);
2135 CheckForRedundantIteration(*this, third.get(), Body);
2136
2137 if (Second.get().second &&
2138 !Diags.isIgnored(diag::warn_comma_operator,
2139 Second.get().second->getExprLoc()))
2140 CommaVisitor(*this).Visit(Second.get().second);
2141
2142 Expr *Third = third.release().getAs<Expr>();
2143 if (isa<NullStmt>(Body))
2144 getCurCompoundScope().setHasEmptyLoopBodies();
2145
2146 return new (Context)
2147 ForStmt(Context, First, Second.get().second, Second.get().first, Third,
2148 Body, ForLoc, LParenLoc, RParenLoc);
2149 }
2150
2151 /// In an Objective C collection iteration statement:
2152 /// for (x in y)
2153 /// x can be an arbitrary l-value expression. Bind it up as a
2154 /// full-expression.
ActOnForEachLValueExpr(Expr * E)2155 StmtResult Sema::ActOnForEachLValueExpr(Expr *E) {
2156 // Reduce placeholder expressions here. Note that this rejects the
2157 // use of pseudo-object l-values in this position.
2158 ExprResult result = CheckPlaceholderExpr(E);
2159 if (result.isInvalid()) return StmtError();
2160 E = result.get();
2161
2162 ExprResult FullExpr = ActOnFinishFullExpr(E, /*DiscardedValue*/ false);
2163 if (FullExpr.isInvalid())
2164 return StmtError();
2165 return StmtResult(static_cast<Stmt*>(FullExpr.get()));
2166 }
2167
2168 ExprResult
CheckObjCForCollectionOperand(SourceLocation forLoc,Expr * collection)2169 Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) {
2170 if (!collection)
2171 return ExprError();
2172
2173 ExprResult result = CorrectDelayedTyposInExpr(collection);
2174 if (!result.isUsable())
2175 return ExprError();
2176 collection = result.get();
2177
2178 // Bail out early if we've got a type-dependent expression.
2179 if (collection->isTypeDependent()) return collection;
2180
2181 // Perform normal l-value conversion.
2182 result = DefaultFunctionArrayLvalueConversion(collection);
2183 if (result.isInvalid())
2184 return ExprError();
2185 collection = result.get();
2186
2187 // The operand needs to have object-pointer type.
2188 // TODO: should we do a contextual conversion?
2189 const ObjCObjectPointerType *pointerType =
2190 collection->getType()->getAs<ObjCObjectPointerType>();
2191 if (!pointerType)
2192 return Diag(forLoc, diag::err_collection_expr_type)
2193 << collection->getType() << collection->getSourceRange();
2194
2195 // Check that the operand provides
2196 // - countByEnumeratingWithState:objects:count:
2197 const ObjCObjectType *objectType = pointerType->getObjectType();
2198 ObjCInterfaceDecl *iface = objectType->getInterface();
2199
2200 // If we have a forward-declared type, we can't do this check.
2201 // Under ARC, it is an error not to have a forward-declared class.
2202 if (iface &&
2203 (getLangOpts().ObjCAutoRefCount
2204 ? RequireCompleteType(forLoc, QualType(objectType, 0),
2205 diag::err_arc_collection_forward, collection)
2206 : !isCompleteType(forLoc, QualType(objectType, 0)))) {
2207 // Otherwise, if we have any useful type information, check that
2208 // the type declares the appropriate method.
2209 } else if (iface || !objectType->qual_empty()) {
2210 IdentifierInfo *selectorIdents[] = {
2211 &Context.Idents.get("countByEnumeratingWithState"),
2212 &Context.Idents.get("objects"),
2213 &Context.Idents.get("count")
2214 };
2215 Selector selector = Context.Selectors.getSelector(3, &selectorIdents[0]);
2216
2217 ObjCMethodDecl *method = nullptr;
2218
2219 // If there's an interface, look in both the public and private APIs.
2220 if (iface) {
2221 method = iface->lookupInstanceMethod(selector);
2222 if (!method) method = iface->lookupPrivateMethod(selector);
2223 }
2224
2225 // Also check protocol qualifiers.
2226 if (!method)
2227 method = LookupMethodInQualifiedType(selector, pointerType,
2228 /*instance*/ true);
2229
2230 // If we didn't find it anywhere, give up.
2231 if (!method) {
2232 Diag(forLoc, diag::warn_collection_expr_type)
2233 << collection->getType() << selector << collection->getSourceRange();
2234 }
2235
2236 // TODO: check for an incompatible signature?
2237 }
2238
2239 // Wrap up any cleanups in the expression.
2240 return collection;
2241 }
2242
2243 StmtResult
ActOnObjCForCollectionStmt(SourceLocation ForLoc,Stmt * First,Expr * collection,SourceLocation RParenLoc)2244 Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
2245 Stmt *First, Expr *collection,
2246 SourceLocation RParenLoc) {
2247 setFunctionHasBranchProtectedScope();
2248
2249 ExprResult CollectionExprResult =
2250 CheckObjCForCollectionOperand(ForLoc, collection);
2251
2252 if (First) {
2253 QualType FirstType;
2254 if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
2255 if (!DS->isSingleDecl())
2256 return StmtError(Diag((*DS->decl_begin())->getLocation(),
2257 diag::err_toomany_element_decls));
2258
2259 VarDecl *D = dyn_cast<VarDecl>(DS->getSingleDecl());
2260 if (!D || D->isInvalidDecl())
2261 return StmtError();
2262
2263 FirstType = D->getType();
2264 // C99 6.8.5p3: The declaration part of a 'for' statement shall only
2265 // declare identifiers for objects having storage class 'auto' or
2266 // 'register'.
2267 if (!D->hasLocalStorage())
2268 return StmtError(Diag(D->getLocation(),
2269 diag::err_non_local_variable_decl_in_for));
2270
2271 // If the type contained 'auto', deduce the 'auto' to 'id'.
2272 if (FirstType->getContainedAutoType()) {
2273 OpaqueValueExpr OpaqueId(D->getLocation(), Context.getObjCIdType(),
2274 VK_RValue);
2275 Expr *DeducedInit = &OpaqueId;
2276 if (DeduceAutoType(D->getTypeSourceInfo(), DeducedInit, FirstType) ==
2277 DAR_Failed)
2278 DiagnoseAutoDeductionFailure(D, DeducedInit);
2279 if (FirstType.isNull()) {
2280 D->setInvalidDecl();
2281 return StmtError();
2282 }
2283
2284 D->setType(FirstType);
2285
2286 if (!inTemplateInstantiation()) {
2287 SourceLocation Loc =
2288 D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
2289 Diag(Loc, diag::warn_auto_var_is_id)
2290 << D->getDeclName();
2291 }
2292 }
2293
2294 } else {
2295 Expr *FirstE = cast<Expr>(First);
2296 if (!FirstE->isTypeDependent() && !FirstE->isLValue())
2297 return StmtError(
2298 Diag(First->getBeginLoc(), diag::err_selector_element_not_lvalue)
2299 << First->getSourceRange());
2300
2301 FirstType = static_cast<Expr*>(First)->getType();
2302 if (FirstType.isConstQualified())
2303 Diag(ForLoc, diag::err_selector_element_const_type)
2304 << FirstType << First->getSourceRange();
2305 }
2306 if (!FirstType->isDependentType() &&
2307 !FirstType->isObjCObjectPointerType() &&
2308 !FirstType->isBlockPointerType())
2309 return StmtError(Diag(ForLoc, diag::err_selector_element_type)
2310 << FirstType << First->getSourceRange());
2311 }
2312
2313 if (CollectionExprResult.isInvalid())
2314 return StmtError();
2315
2316 CollectionExprResult =
2317 ActOnFinishFullExpr(CollectionExprResult.get(), /*DiscardedValue*/ false);
2318 if (CollectionExprResult.isInvalid())
2319 return StmtError();
2320
2321 return new (Context) ObjCForCollectionStmt(First, CollectionExprResult.get(),
2322 nullptr, ForLoc, RParenLoc);
2323 }
2324
2325 /// Finish building a variable declaration for a for-range statement.
2326 /// \return true if an error occurs.
FinishForRangeVarDecl(Sema & SemaRef,VarDecl * Decl,Expr * Init,SourceLocation Loc,int DiagID)2327 static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
2328 SourceLocation Loc, int DiagID) {
2329 if (Decl->getType()->isUndeducedType()) {
2330 ExprResult Res = SemaRef.CorrectDelayedTyposInExpr(Init);
2331 if (!Res.isUsable()) {
2332 Decl->setInvalidDecl();
2333 return true;
2334 }
2335 Init = Res.get();
2336 }
2337
2338 // Deduce the type for the iterator variable now rather than leaving it to
2339 // AddInitializerToDecl, so we can produce a more suitable diagnostic.
2340 QualType InitType;
2341 if ((!isa<InitListExpr>(Init) && Init->getType()->isVoidType()) ||
2342 SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitType) ==
2343 Sema::DAR_Failed)
2344 SemaRef.Diag(Loc, DiagID) << Init->getType();
2345 if (InitType.isNull()) {
2346 Decl->setInvalidDecl();
2347 return true;
2348 }
2349 Decl->setType(InitType);
2350
2351 // In ARC, infer lifetime.
2352 // FIXME: ARC may want to turn this into 'const __unsafe_unretained' if
2353 // we're doing the equivalent of fast iteration.
2354 if (SemaRef.getLangOpts().ObjCAutoRefCount &&
2355 SemaRef.inferObjCARCLifetime(Decl))
2356 Decl->setInvalidDecl();
2357
2358 SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false);
2359 SemaRef.FinalizeDeclaration(Decl);
2360 SemaRef.CurContext->addHiddenDecl(Decl);
2361 return false;
2362 }
2363
2364 namespace {
2365 // An enum to represent whether something is dealing with a call to begin()
2366 // or a call to end() in a range-based for loop.
2367 enum BeginEndFunction {
2368 BEF_begin,
2369 BEF_end
2370 };
2371
2372 /// Produce a note indicating which begin/end function was implicitly called
2373 /// by a C++11 for-range statement. This is often not obvious from the code,
2374 /// nor from the diagnostics produced when analysing the implicit expressions
2375 /// required in a for-range statement.
NoteForRangeBeginEndFunction(Sema & SemaRef,Expr * E,BeginEndFunction BEF)2376 void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E,
2377 BeginEndFunction BEF) {
2378 CallExpr *CE = dyn_cast<CallExpr>(E);
2379 if (!CE)
2380 return;
2381 FunctionDecl *D = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
2382 if (!D)
2383 return;
2384 SourceLocation Loc = D->getLocation();
2385
2386 std::string Description;
2387 bool IsTemplate = false;
2388 if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) {
2389 Description = SemaRef.getTemplateArgumentBindingsText(
2390 FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs());
2391 IsTemplate = true;
2392 }
2393
2394 SemaRef.Diag(Loc, diag::note_for_range_begin_end)
2395 << BEF << IsTemplate << Description << E->getType();
2396 }
2397
2398 /// Build a variable declaration for a for-range statement.
BuildForRangeVarDecl(Sema & SemaRef,SourceLocation Loc,QualType Type,StringRef Name)2399 VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc,
2400 QualType Type, StringRef Name) {
2401 DeclContext *DC = SemaRef.CurContext;
2402 IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name);
2403 TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc);
2404 VarDecl *Decl = VarDecl::Create(SemaRef.Context, DC, Loc, Loc, II, Type,
2405 TInfo, SC_None);
2406 Decl->setImplicit();
2407 return Decl;
2408 }
2409
2410 }
2411
ObjCEnumerationCollection(Expr * Collection)2412 static bool ObjCEnumerationCollection(Expr *Collection) {
2413 return !Collection->isTypeDependent()
2414 && Collection->getType()->getAs<ObjCObjectPointerType>() != nullptr;
2415 }
2416
2417 /// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement.
2418 ///
2419 /// C++11 [stmt.ranged]:
2420 /// A range-based for statement is equivalent to
2421 ///
2422 /// {
2423 /// auto && __range = range-init;
2424 /// for ( auto __begin = begin-expr,
2425 /// __end = end-expr;
2426 /// __begin != __end;
2427 /// ++__begin ) {
2428 /// for-range-declaration = *__begin;
2429 /// statement
2430 /// }
2431 /// }
2432 ///
2433 /// The body of the loop is not available yet, since it cannot be analysed until
2434 /// we have determined the type of the for-range-declaration.
ActOnCXXForRangeStmt(Scope * S,SourceLocation ForLoc,SourceLocation CoawaitLoc,Stmt * InitStmt,Stmt * First,SourceLocation ColonLoc,Expr * Range,SourceLocation RParenLoc,BuildForRangeKind Kind)2435 StmtResult Sema::ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc,
2436 SourceLocation CoawaitLoc, Stmt *InitStmt,
2437 Stmt *First, SourceLocation ColonLoc,
2438 Expr *Range, SourceLocation RParenLoc,
2439 BuildForRangeKind Kind) {
2440 if (!First)
2441 return StmtError();
2442
2443 if (Range && ObjCEnumerationCollection(Range)) {
2444 // FIXME: Support init-statements in Objective-C++20 ranged for statement.
2445 if (InitStmt)
2446 return Diag(InitStmt->getBeginLoc(), diag::err_objc_for_range_init_stmt)
2447 << InitStmt->getSourceRange();
2448 return ActOnObjCForCollectionStmt(ForLoc, First, Range, RParenLoc);
2449 }
2450
2451 DeclStmt *DS = dyn_cast<DeclStmt>(First);
2452 assert(DS && "first part of for range not a decl stmt");
2453
2454 if (!DS->isSingleDecl()) {
2455 Diag(DS->getBeginLoc(), diag::err_type_defined_in_for_range);
2456 return StmtError();
2457 }
2458
2459 // This function is responsible for attaching an initializer to LoopVar. We
2460 // must call ActOnInitializerError if we fail to do so.
2461 Decl *LoopVar = DS->getSingleDecl();
2462 if (LoopVar->isInvalidDecl() || !Range ||
2463 DiagnoseUnexpandedParameterPack(Range, UPPC_Expression)) {
2464 ActOnInitializerError(LoopVar);
2465 return StmtError();
2466 }
2467
2468 // Build the coroutine state immediately and not later during template
2469 // instantiation
2470 if (!CoawaitLoc.isInvalid()) {
2471 if (!ActOnCoroutineBodyStart(S, CoawaitLoc, "co_await")) {
2472 ActOnInitializerError(LoopVar);
2473 return StmtError();
2474 }
2475 }
2476
2477 // Build auto && __range = range-init
2478 // Divide by 2, since the variables are in the inner scope (loop body).
2479 const auto DepthStr = std::to_string(S->getDepth() / 2);
2480 SourceLocation RangeLoc = Range->getBeginLoc();
2481 VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc,
2482 Context.getAutoRRefDeductType(),
2483 std::string("__range") + DepthStr);
2484 if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc,
2485 diag::err_for_range_deduction_failure)) {
2486 ActOnInitializerError(LoopVar);
2487 return StmtError();
2488 }
2489
2490 // Claim the type doesn't contain auto: we've already done the checking.
2491 DeclGroupPtrTy RangeGroup =
2492 BuildDeclaratorGroup(MutableArrayRef<Decl *>((Decl **)&RangeVar, 1));
2493 StmtResult RangeDecl = ActOnDeclStmt(RangeGroup, RangeLoc, RangeLoc);
2494 if (RangeDecl.isInvalid()) {
2495 ActOnInitializerError(LoopVar);
2496 return StmtError();
2497 }
2498
2499 StmtResult R = BuildCXXForRangeStmt(
2500 ForLoc, CoawaitLoc, InitStmt, ColonLoc, RangeDecl.get(),
2501 /*BeginStmt=*/nullptr, /*EndStmt=*/nullptr,
2502 /*Cond=*/nullptr, /*Inc=*/nullptr, DS, RParenLoc, Kind);
2503 if (R.isInvalid()) {
2504 ActOnInitializerError(LoopVar);
2505 return StmtError();
2506 }
2507
2508 return R;
2509 }
2510
2511 /// Create the initialization, compare, and increment steps for
2512 /// the range-based for loop expression.
2513 /// This function does not handle array-based for loops,
2514 /// which are created in Sema::BuildCXXForRangeStmt.
2515 ///
2516 /// \returns a ForRangeStatus indicating success or what kind of error occurred.
2517 /// BeginExpr and EndExpr are set and FRS_Success is returned on success;
2518 /// CandidateSet and BEF are set and some non-success value is returned on
2519 /// failure.
2520 static Sema::ForRangeStatus
BuildNonArrayForRange(Sema & SemaRef,Expr * BeginRange,Expr * EndRange,QualType RangeType,VarDecl * BeginVar,VarDecl * EndVar,SourceLocation ColonLoc,SourceLocation CoawaitLoc,OverloadCandidateSet * CandidateSet,ExprResult * BeginExpr,ExprResult * EndExpr,BeginEndFunction * BEF)2521 BuildNonArrayForRange(Sema &SemaRef, Expr *BeginRange, Expr *EndRange,
2522 QualType RangeType, VarDecl *BeginVar, VarDecl *EndVar,
2523 SourceLocation ColonLoc, SourceLocation CoawaitLoc,
2524 OverloadCandidateSet *CandidateSet, ExprResult *BeginExpr,
2525 ExprResult *EndExpr, BeginEndFunction *BEF) {
2526 DeclarationNameInfo BeginNameInfo(
2527 &SemaRef.PP.getIdentifierTable().get("begin"), ColonLoc);
2528 DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get("end"),
2529 ColonLoc);
2530
2531 LookupResult BeginMemberLookup(SemaRef, BeginNameInfo,
2532 Sema::LookupMemberName);
2533 LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName);
2534
2535 auto BuildBegin = [&] {
2536 *BEF = BEF_begin;
2537 Sema::ForRangeStatus RangeStatus =
2538 SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, BeginNameInfo,
2539 BeginMemberLookup, CandidateSet,
2540 BeginRange, BeginExpr);
2541
2542 if (RangeStatus != Sema::FRS_Success) {
2543 if (RangeStatus == Sema::FRS_DiagnosticIssued)
2544 SemaRef.Diag(BeginRange->getBeginLoc(), diag::note_in_for_range)
2545 << ColonLoc << BEF_begin << BeginRange->getType();
2546 return RangeStatus;
2547 }
2548 if (!CoawaitLoc.isInvalid()) {
2549 // FIXME: getCurScope() should not be used during template instantiation.
2550 // We should pick up the set of unqualified lookup results for operator
2551 // co_await during the initial parse.
2552 *BeginExpr = SemaRef.ActOnCoawaitExpr(SemaRef.getCurScope(), ColonLoc,
2553 BeginExpr->get());
2554 if (BeginExpr->isInvalid())
2555 return Sema::FRS_DiagnosticIssued;
2556 }
2557 if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc,
2558 diag::err_for_range_iter_deduction_failure)) {
2559 NoteForRangeBeginEndFunction(SemaRef, BeginExpr->get(), *BEF);
2560 return Sema::FRS_DiagnosticIssued;
2561 }
2562 return Sema::FRS_Success;
2563 };
2564
2565 auto BuildEnd = [&] {
2566 *BEF = BEF_end;
2567 Sema::ForRangeStatus RangeStatus =
2568 SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, EndNameInfo,
2569 EndMemberLookup, CandidateSet,
2570 EndRange, EndExpr);
2571 if (RangeStatus != Sema::FRS_Success) {
2572 if (RangeStatus == Sema::FRS_DiagnosticIssued)
2573 SemaRef.Diag(EndRange->getBeginLoc(), diag::note_in_for_range)
2574 << ColonLoc << BEF_end << EndRange->getType();
2575 return RangeStatus;
2576 }
2577 if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc,
2578 diag::err_for_range_iter_deduction_failure)) {
2579 NoteForRangeBeginEndFunction(SemaRef, EndExpr->get(), *BEF);
2580 return Sema::FRS_DiagnosticIssued;
2581 }
2582 return Sema::FRS_Success;
2583 };
2584
2585 if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) {
2586 // - if _RangeT is a class type, the unqualified-ids begin and end are
2587 // looked up in the scope of class _RangeT as if by class member access
2588 // lookup (3.4.5), and if either (or both) finds at least one
2589 // declaration, begin-expr and end-expr are __range.begin() and
2590 // __range.end(), respectively;
2591 SemaRef.LookupQualifiedName(BeginMemberLookup, D);
2592 if (BeginMemberLookup.isAmbiguous())
2593 return Sema::FRS_DiagnosticIssued;
2594
2595 SemaRef.LookupQualifiedName(EndMemberLookup, D);
2596 if (EndMemberLookup.isAmbiguous())
2597 return Sema::FRS_DiagnosticIssued;
2598
2599 if (BeginMemberLookup.empty() != EndMemberLookup.empty()) {
2600 // Look up the non-member form of the member we didn't find, first.
2601 // This way we prefer a "no viable 'end'" diagnostic over a "i found
2602 // a 'begin' but ignored it because there was no member 'end'"
2603 // diagnostic.
2604 auto BuildNonmember = [&](
2605 BeginEndFunction BEFFound, LookupResult &Found,
2606 llvm::function_ref<Sema::ForRangeStatus()> BuildFound,
2607 llvm::function_ref<Sema::ForRangeStatus()> BuildNotFound) {
2608 LookupResult OldFound = std::move(Found);
2609 Found.clear();
2610
2611 if (Sema::ForRangeStatus Result = BuildNotFound())
2612 return Result;
2613
2614 switch (BuildFound()) {
2615 case Sema::FRS_Success:
2616 return Sema::FRS_Success;
2617
2618 case Sema::FRS_NoViableFunction:
2619 CandidateSet->NoteCandidates(
2620 PartialDiagnosticAt(BeginRange->getBeginLoc(),
2621 SemaRef.PDiag(diag::err_for_range_invalid)
2622 << BeginRange->getType() << BEFFound),
2623 SemaRef, OCD_AllCandidates, BeginRange);
2624 LLVM_FALLTHROUGH;
2625
2626 case Sema::FRS_DiagnosticIssued:
2627 for (NamedDecl *D : OldFound) {
2628 SemaRef.Diag(D->getLocation(),
2629 diag::note_for_range_member_begin_end_ignored)
2630 << BeginRange->getType() << BEFFound;
2631 }
2632 return Sema::FRS_DiagnosticIssued;
2633 }
2634 llvm_unreachable("unexpected ForRangeStatus");
2635 };
2636 if (BeginMemberLookup.empty())
2637 return BuildNonmember(BEF_end, EndMemberLookup, BuildEnd, BuildBegin);
2638 return BuildNonmember(BEF_begin, BeginMemberLookup, BuildBegin, BuildEnd);
2639 }
2640 } else {
2641 // - otherwise, begin-expr and end-expr are begin(__range) and
2642 // end(__range), respectively, where begin and end are looked up with
2643 // argument-dependent lookup (3.4.2). For the purposes of this name
2644 // lookup, namespace std is an associated namespace.
2645 }
2646
2647 if (Sema::ForRangeStatus Result = BuildBegin())
2648 return Result;
2649 return BuildEnd();
2650 }
2651
2652 /// Speculatively attempt to dereference an invalid range expression.
2653 /// If the attempt fails, this function will return a valid, null StmtResult
2654 /// and emit no diagnostics.
RebuildForRangeWithDereference(Sema & SemaRef,Scope * S,SourceLocation ForLoc,SourceLocation CoawaitLoc,Stmt * InitStmt,Stmt * LoopVarDecl,SourceLocation ColonLoc,Expr * Range,SourceLocation RangeLoc,SourceLocation RParenLoc)2655 static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S,
2656 SourceLocation ForLoc,
2657 SourceLocation CoawaitLoc,
2658 Stmt *InitStmt,
2659 Stmt *LoopVarDecl,
2660 SourceLocation ColonLoc,
2661 Expr *Range,
2662 SourceLocation RangeLoc,
2663 SourceLocation RParenLoc) {
2664 // Determine whether we can rebuild the for-range statement with a
2665 // dereferenced range expression.
2666 ExprResult AdjustedRange;
2667 {
2668 Sema::SFINAETrap Trap(SemaRef);
2669
2670 AdjustedRange = SemaRef.BuildUnaryOp(S, RangeLoc, UO_Deref, Range);
2671 if (AdjustedRange.isInvalid())
2672 return StmtResult();
2673
2674 StmtResult SR = SemaRef.ActOnCXXForRangeStmt(
2675 S, ForLoc, CoawaitLoc, InitStmt, LoopVarDecl, ColonLoc,
2676 AdjustedRange.get(), RParenLoc, Sema::BFRK_Check);
2677 if (SR.isInvalid())
2678 return StmtResult();
2679 }
2680
2681 // The attempt to dereference worked well enough that it could produce a valid
2682 // loop. Produce a fixit, and rebuild the loop with diagnostics enabled, in
2683 // case there are any other (non-fatal) problems with it.
2684 SemaRef.Diag(RangeLoc, diag::err_for_range_dereference)
2685 << Range->getType() << FixItHint::CreateInsertion(RangeLoc, "*");
2686 return SemaRef.ActOnCXXForRangeStmt(
2687 S, ForLoc, CoawaitLoc, InitStmt, LoopVarDecl, ColonLoc,
2688 AdjustedRange.get(), RParenLoc, Sema::BFRK_Rebuild);
2689 }
2690
2691 /// BuildCXXForRangeStmt - Build or instantiate a C++11 for-range statement.
BuildCXXForRangeStmt(SourceLocation ForLoc,SourceLocation CoawaitLoc,Stmt * InitStmt,SourceLocation ColonLoc,Stmt * RangeDecl,Stmt * Begin,Stmt * End,Expr * Cond,Expr * Inc,Stmt * LoopVarDecl,SourceLocation RParenLoc,BuildForRangeKind Kind)2692 StmtResult Sema::BuildCXXForRangeStmt(SourceLocation ForLoc,
2693 SourceLocation CoawaitLoc, Stmt *InitStmt,
2694 SourceLocation ColonLoc, Stmt *RangeDecl,
2695 Stmt *Begin, Stmt *End, Expr *Cond,
2696 Expr *Inc, Stmt *LoopVarDecl,
2697 SourceLocation RParenLoc,
2698 BuildForRangeKind Kind) {
2699 // FIXME: This should not be used during template instantiation. We should
2700 // pick up the set of unqualified lookup results for the != and + operators
2701 // in the initial parse.
2702 //
2703 // Testcase (accepts-invalid):
2704 // template<typename T> void f() { for (auto x : T()) {} }
2705 // namespace N { struct X { X begin(); X end(); int operator*(); }; }
2706 // bool operator!=(N::X, N::X); void operator++(N::X);
2707 // void g() { f<N::X>(); }
2708 Scope *S = getCurScope();
2709
2710 DeclStmt *RangeDS = cast<DeclStmt>(RangeDecl);
2711 VarDecl *RangeVar = cast<VarDecl>(RangeDS->getSingleDecl());
2712 QualType RangeVarType = RangeVar->getType();
2713
2714 DeclStmt *LoopVarDS = cast<DeclStmt>(LoopVarDecl);
2715 VarDecl *LoopVar = cast<VarDecl>(LoopVarDS->getSingleDecl());
2716
2717 StmtResult BeginDeclStmt = Begin;
2718 StmtResult EndDeclStmt = End;
2719 ExprResult NotEqExpr = Cond, IncrExpr = Inc;
2720
2721 if (RangeVarType->isDependentType()) {
2722 // The range is implicitly used as a placeholder when it is dependent.
2723 RangeVar->markUsed(Context);
2724
2725 // Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill
2726 // them in properly when we instantiate the loop.
2727 if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
2728 if (auto *DD = dyn_cast<DecompositionDecl>(LoopVar))
2729 for (auto *Binding : DD->bindings())
2730 Binding->setType(Context.DependentTy);
2731 LoopVar->setType(SubstAutoType(LoopVar->getType(), Context.DependentTy));
2732 }
2733 } else if (!BeginDeclStmt.get()) {
2734 SourceLocation RangeLoc = RangeVar->getLocation();
2735
2736 const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType();
2737
2738 ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2739 VK_LValue, ColonLoc);
2740 if (BeginRangeRef.isInvalid())
2741 return StmtError();
2742
2743 ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType,
2744 VK_LValue, ColonLoc);
2745 if (EndRangeRef.isInvalid())
2746 return StmtError();
2747
2748 QualType AutoType = Context.getAutoDeductType();
2749 Expr *Range = RangeVar->getInit();
2750 if (!Range)
2751 return StmtError();
2752 QualType RangeType = Range->getType();
2753
2754 if (RequireCompleteType(RangeLoc, RangeType,
2755 diag::err_for_range_incomplete_type))
2756 return StmtError();
2757
2758 // Build auto __begin = begin-expr, __end = end-expr.
2759 // Divide by 2, since the variables are in the inner scope (loop body).
2760 const auto DepthStr = std::to_string(S->getDepth() / 2);
2761 VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2762 std::string("__begin") + DepthStr);
2763 VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType,
2764 std::string("__end") + DepthStr);
2765
2766 // Build begin-expr and end-expr and attach to __begin and __end variables.
2767 ExprResult BeginExpr, EndExpr;
2768 if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) {
2769 // - if _RangeT is an array type, begin-expr and end-expr are __range and
2770 // __range + __bound, respectively, where __bound is the array bound. If
2771 // _RangeT is an array of unknown size or an array of incomplete type,
2772 // the program is ill-formed;
2773
2774 // begin-expr is __range.
2775 BeginExpr = BeginRangeRef;
2776 if (!CoawaitLoc.isInvalid()) {
2777 BeginExpr = ActOnCoawaitExpr(S, ColonLoc, BeginExpr.get());
2778 if (BeginExpr.isInvalid())
2779 return StmtError();
2780 }
2781 if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc,
2782 diag::err_for_range_iter_deduction_failure)) {
2783 NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2784 return StmtError();
2785 }
2786
2787 // Find the array bound.
2788 ExprResult BoundExpr;
2789 if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(UnqAT))
2790 BoundExpr = IntegerLiteral::Create(
2791 Context, CAT->getSize(), Context.getPointerDiffType(), RangeLoc);
2792 else if (const VariableArrayType *VAT =
2793 dyn_cast<VariableArrayType>(UnqAT)) {
2794 // For a variably modified type we can't just use the expression within
2795 // the array bounds, since we don't want that to be re-evaluated here.
2796 // Rather, we need to determine what it was when the array was first
2797 // created - so we resort to using sizeof(vla)/sizeof(element).
2798 // For e.g.
2799 // void f(int b) {
2800 // int vla[b];
2801 // b = -1; <-- This should not affect the num of iterations below
2802 // for (int &c : vla) { .. }
2803 // }
2804
2805 // FIXME: This results in codegen generating IR that recalculates the
2806 // run-time number of elements (as opposed to just using the IR Value
2807 // that corresponds to the run-time value of each bound that was
2808 // generated when the array was created.) If this proves too embarrassing
2809 // even for unoptimized IR, consider passing a magic-value/cookie to
2810 // codegen that then knows to simply use that initial llvm::Value (that
2811 // corresponds to the bound at time of array creation) within
2812 // getelementptr. But be prepared to pay the price of increasing a
2813 // customized form of coupling between the two components - which could
2814 // be hard to maintain as the codebase evolves.
2815
2816 ExprResult SizeOfVLAExprR = ActOnUnaryExprOrTypeTraitExpr(
2817 EndVar->getLocation(), UETT_SizeOf,
2818 /*IsType=*/true,
2819 CreateParsedType(VAT->desugar(), Context.getTrivialTypeSourceInfo(
2820 VAT->desugar(), RangeLoc))
2821 .getAsOpaquePtr(),
2822 EndVar->getSourceRange());
2823 if (SizeOfVLAExprR.isInvalid())
2824 return StmtError();
2825
2826 ExprResult SizeOfEachElementExprR = ActOnUnaryExprOrTypeTraitExpr(
2827 EndVar->getLocation(), UETT_SizeOf,
2828 /*IsType=*/true,
2829 CreateParsedType(VAT->desugar(),
2830 Context.getTrivialTypeSourceInfo(
2831 VAT->getElementType(), RangeLoc))
2832 .getAsOpaquePtr(),
2833 EndVar->getSourceRange());
2834 if (SizeOfEachElementExprR.isInvalid())
2835 return StmtError();
2836
2837 BoundExpr =
2838 ActOnBinOp(S, EndVar->getLocation(), tok::slash,
2839 SizeOfVLAExprR.get(), SizeOfEachElementExprR.get());
2840 if (BoundExpr.isInvalid())
2841 return StmtError();
2842
2843 } else {
2844 // Can't be a DependentSizedArrayType or an IncompleteArrayType since
2845 // UnqAT is not incomplete and Range is not type-dependent.
2846 llvm_unreachable("Unexpected array type in for-range");
2847 }
2848
2849 // end-expr is __range + __bound.
2850 EndExpr = ActOnBinOp(S, ColonLoc, tok::plus, EndRangeRef.get(),
2851 BoundExpr.get());
2852 if (EndExpr.isInvalid())
2853 return StmtError();
2854 if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc,
2855 diag::err_for_range_iter_deduction_failure)) {
2856 NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2857 return StmtError();
2858 }
2859 } else {
2860 OverloadCandidateSet CandidateSet(RangeLoc,
2861 OverloadCandidateSet::CSK_Normal);
2862 BeginEndFunction BEFFailure;
2863 ForRangeStatus RangeStatus = BuildNonArrayForRange(
2864 *this, BeginRangeRef.get(), EndRangeRef.get(), RangeType, BeginVar,
2865 EndVar, ColonLoc, CoawaitLoc, &CandidateSet, &BeginExpr, &EndExpr,
2866 &BEFFailure);
2867
2868 if (Kind == BFRK_Build && RangeStatus == FRS_NoViableFunction &&
2869 BEFFailure == BEF_begin) {
2870 // If the range is being built from an array parameter, emit a
2871 // a diagnostic that it is being treated as a pointer.
2872 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Range)) {
2873 if (ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
2874 QualType ArrayTy = PVD->getOriginalType();
2875 QualType PointerTy = PVD->getType();
2876 if (PointerTy->isPointerType() && ArrayTy->isArrayType()) {
2877 Diag(Range->getBeginLoc(), diag::err_range_on_array_parameter)
2878 << RangeLoc << PVD << ArrayTy << PointerTy;
2879 Diag(PVD->getLocation(), diag::note_declared_at);
2880 return StmtError();
2881 }
2882 }
2883 }
2884
2885 // If building the range failed, try dereferencing the range expression
2886 // unless a diagnostic was issued or the end function is problematic.
2887 StmtResult SR = RebuildForRangeWithDereference(*this, S, ForLoc,
2888 CoawaitLoc, InitStmt,
2889 LoopVarDecl, ColonLoc,
2890 Range, RangeLoc,
2891 RParenLoc);
2892 if (SR.isInvalid() || SR.isUsable())
2893 return SR;
2894 }
2895
2896 // Otherwise, emit diagnostics if we haven't already.
2897 if (RangeStatus == FRS_NoViableFunction) {
2898 Expr *Range = BEFFailure ? EndRangeRef.get() : BeginRangeRef.get();
2899 CandidateSet.NoteCandidates(
2900 PartialDiagnosticAt(Range->getBeginLoc(),
2901 PDiag(diag::err_for_range_invalid)
2902 << RangeLoc << Range->getType()
2903 << BEFFailure),
2904 *this, OCD_AllCandidates, Range);
2905 }
2906 // Return an error if no fix was discovered.
2907 if (RangeStatus != FRS_Success)
2908 return StmtError();
2909 }
2910
2911 assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() &&
2912 "invalid range expression in for loop");
2913
2914 // C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same.
2915 // C++1z removes this restriction.
2916 QualType BeginType = BeginVar->getType(), EndType = EndVar->getType();
2917 if (!Context.hasSameType(BeginType, EndType)) {
2918 Diag(RangeLoc, getLangOpts().CPlusPlus17
2919 ? diag::warn_for_range_begin_end_types_differ
2920 : diag::ext_for_range_begin_end_types_differ)
2921 << BeginType << EndType;
2922 NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2923 NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2924 }
2925
2926 BeginDeclStmt =
2927 ActOnDeclStmt(ConvertDeclToDeclGroup(BeginVar), ColonLoc, ColonLoc);
2928 EndDeclStmt =
2929 ActOnDeclStmt(ConvertDeclToDeclGroup(EndVar), ColonLoc, ColonLoc);
2930
2931 const QualType BeginRefNonRefType = BeginType.getNonReferenceType();
2932 ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2933 VK_LValue, ColonLoc);
2934 if (BeginRef.isInvalid())
2935 return StmtError();
2936
2937 ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(),
2938 VK_LValue, ColonLoc);
2939 if (EndRef.isInvalid())
2940 return StmtError();
2941
2942 // Build and check __begin != __end expression.
2943 NotEqExpr = ActOnBinOp(S, ColonLoc, tok::exclaimequal,
2944 BeginRef.get(), EndRef.get());
2945 if (!NotEqExpr.isInvalid())
2946 NotEqExpr = CheckBooleanCondition(ColonLoc, NotEqExpr.get());
2947 if (!NotEqExpr.isInvalid())
2948 NotEqExpr =
2949 ActOnFinishFullExpr(NotEqExpr.get(), /*DiscardedValue*/ false);
2950 if (NotEqExpr.isInvalid()) {
2951 Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2952 << RangeLoc << 0 << BeginRangeRef.get()->getType();
2953 NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2954 if (!Context.hasSameType(BeginType, EndType))
2955 NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end);
2956 return StmtError();
2957 }
2958
2959 // Build and check ++__begin expression.
2960 BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2961 VK_LValue, ColonLoc);
2962 if (BeginRef.isInvalid())
2963 return StmtError();
2964
2965 IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get());
2966 if (!IncrExpr.isInvalid() && CoawaitLoc.isValid())
2967 // FIXME: getCurScope() should not be used during template instantiation.
2968 // We should pick up the set of unqualified lookup results for operator
2969 // co_await during the initial parse.
2970 IncrExpr = ActOnCoawaitExpr(S, CoawaitLoc, IncrExpr.get());
2971 if (!IncrExpr.isInvalid())
2972 IncrExpr = ActOnFinishFullExpr(IncrExpr.get(), /*DiscardedValue*/ false);
2973 if (IncrExpr.isInvalid()) {
2974 Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2975 << RangeLoc << 2 << BeginRangeRef.get()->getType() ;
2976 NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2977 return StmtError();
2978 }
2979
2980 // Build and check *__begin expression.
2981 BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType,
2982 VK_LValue, ColonLoc);
2983 if (BeginRef.isInvalid())
2984 return StmtError();
2985
2986 ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get());
2987 if (DerefExpr.isInvalid()) {
2988 Diag(RangeLoc, diag::note_for_range_invalid_iterator)
2989 << RangeLoc << 1 << BeginRangeRef.get()->getType();
2990 NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
2991 return StmtError();
2992 }
2993
2994 // Attach *__begin as initializer for VD. Don't touch it if we're just
2995 // trying to determine whether this would be a valid range.
2996 if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) {
2997 AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false);
2998 if (LoopVar->isInvalidDecl() ||
2999 (LoopVar->getInit() && LoopVar->getInit()->containsErrors()))
3000 NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin);
3001 }
3002 }
3003
3004 // Don't bother to actually allocate the result if we're just trying to
3005 // determine whether it would be valid.
3006 if (Kind == BFRK_Check)
3007 return StmtResult();
3008
3009 // In OpenMP loop region loop control variable must be private. Perform
3010 // analysis of first part (if any).
3011 if (getLangOpts().OpenMP >= 50 && BeginDeclStmt.isUsable())
3012 ActOnOpenMPLoopInitialization(ForLoc, BeginDeclStmt.get());
3013
3014 return new (Context) CXXForRangeStmt(
3015 InitStmt, RangeDS, cast_or_null<DeclStmt>(BeginDeclStmt.get()),
3016 cast_or_null<DeclStmt>(EndDeclStmt.get()), NotEqExpr.get(),
3017 IncrExpr.get(), LoopVarDS, /*Body=*/nullptr, ForLoc, CoawaitLoc,
3018 ColonLoc, RParenLoc);
3019 }
3020
3021 /// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach
3022 /// statement.
FinishObjCForCollectionStmt(Stmt * S,Stmt * B)3023 StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) {
3024 if (!S || !B)
3025 return StmtError();
3026 ObjCForCollectionStmt * ForStmt = cast<ObjCForCollectionStmt>(S);
3027
3028 ForStmt->setBody(B);
3029 return S;
3030 }
3031
3032 // Warn when the loop variable is a const reference that creates a copy.
3033 // Suggest using the non-reference type for copies. If a copy can be prevented
3034 // suggest the const reference type that would do so.
3035 // For instance, given "for (const &Foo : Range)", suggest
3036 // "for (const Foo : Range)" to denote a copy is made for the loop. If
3037 // possible, also suggest "for (const &Bar : Range)" if this type prevents
3038 // the copy altogether.
DiagnoseForRangeReferenceVariableCopies(Sema & SemaRef,const VarDecl * VD,QualType RangeInitType)3039 static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef,
3040 const VarDecl *VD,
3041 QualType RangeInitType) {
3042 const Expr *InitExpr = VD->getInit();
3043 if (!InitExpr)
3044 return;
3045
3046 QualType VariableType = VD->getType();
3047
3048 if (auto Cleanups = dyn_cast<ExprWithCleanups>(InitExpr))
3049 if (!Cleanups->cleanupsHaveSideEffects())
3050 InitExpr = Cleanups->getSubExpr();
3051
3052 const MaterializeTemporaryExpr *MTE =
3053 dyn_cast<MaterializeTemporaryExpr>(InitExpr);
3054
3055 // No copy made.
3056 if (!MTE)
3057 return;
3058
3059 const Expr *E = MTE->getSubExpr()->IgnoreImpCasts();
3060
3061 // Searching for either UnaryOperator for dereference of a pointer or
3062 // CXXOperatorCallExpr for handling iterators.
3063 while (!isa<CXXOperatorCallExpr>(E) && !isa<UnaryOperator>(E)) {
3064 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(E)) {
3065 E = CCE->getArg(0);
3066 } else if (const CXXMemberCallExpr *Call = dyn_cast<CXXMemberCallExpr>(E)) {
3067 const MemberExpr *ME = cast<MemberExpr>(Call->getCallee());
3068 E = ME->getBase();
3069 } else {
3070 const MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E);
3071 E = MTE->getSubExpr();
3072 }
3073 E = E->IgnoreImpCasts();
3074 }
3075
3076 QualType ReferenceReturnType;
3077 if (isa<UnaryOperator>(E)) {
3078 ReferenceReturnType = SemaRef.Context.getLValueReferenceType(E->getType());
3079 } else {
3080 const CXXOperatorCallExpr *Call = cast<CXXOperatorCallExpr>(E);
3081 const FunctionDecl *FD = Call->getDirectCallee();
3082 QualType ReturnType = FD->getReturnType();
3083 if (ReturnType->isReferenceType())
3084 ReferenceReturnType = ReturnType;
3085 }
3086
3087 if (!ReferenceReturnType.isNull()) {
3088 // Loop variable creates a temporary. Suggest either to go with
3089 // non-reference loop variable to indicate a copy is made, or
3090 // the correct type to bind a const reference.
3091 SemaRef.Diag(VD->getLocation(),
3092 diag::warn_for_range_const_ref_binds_temp_built_from_ref)
3093 << VD << VariableType << ReferenceReturnType;
3094 QualType NonReferenceType = VariableType.getNonReferenceType();
3095 NonReferenceType.removeLocalConst();
3096 QualType NewReferenceType =
3097 SemaRef.Context.getLValueReferenceType(E->getType().withConst());
3098 SemaRef.Diag(VD->getBeginLoc(), diag::note_use_type_or_non_reference)
3099 << NonReferenceType << NewReferenceType << VD->getSourceRange()
3100 << FixItHint::CreateRemoval(VD->getTypeSpecEndLoc());
3101 } else if (!VariableType->isRValueReferenceType()) {
3102 // The range always returns a copy, so a temporary is always created.
3103 // Suggest removing the reference from the loop variable.
3104 // If the type is a rvalue reference do not warn since that changes the
3105 // semantic of the code.
3106 SemaRef.Diag(VD->getLocation(), diag::warn_for_range_ref_binds_ret_temp)
3107 << VD << RangeInitType;
3108 QualType NonReferenceType = VariableType.getNonReferenceType();
3109 NonReferenceType.removeLocalConst();
3110 SemaRef.Diag(VD->getBeginLoc(), diag::note_use_non_reference_type)
3111 << NonReferenceType << VD->getSourceRange()
3112 << FixItHint::CreateRemoval(VD->getTypeSpecEndLoc());
3113 }
3114 }
3115
3116 /// Determines whether the @p VariableType's declaration is a record with the
3117 /// clang::trivial_abi attribute.
hasTrivialABIAttr(QualType VariableType)3118 static bool hasTrivialABIAttr(QualType VariableType) {
3119 if (CXXRecordDecl *RD = VariableType->getAsCXXRecordDecl())
3120 return RD->hasAttr<TrivialABIAttr>();
3121
3122 return false;
3123 }
3124
3125 // Warns when the loop variable can be changed to a reference type to
3126 // prevent a copy. For instance, if given "for (const Foo x : Range)" suggest
3127 // "for (const Foo &x : Range)" if this form does not make a copy.
DiagnoseForRangeConstVariableCopies(Sema & SemaRef,const VarDecl * VD)3128 static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef,
3129 const VarDecl *VD) {
3130 const Expr *InitExpr = VD->getInit();
3131 if (!InitExpr)
3132 return;
3133
3134 QualType VariableType = VD->getType();
3135
3136 if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(InitExpr)) {
3137 if (!CE->getConstructor()->isCopyConstructor())
3138 return;
3139 } else if (const CastExpr *CE = dyn_cast<CastExpr>(InitExpr)) {
3140 if (CE->getCastKind() != CK_LValueToRValue)
3141 return;
3142 } else {
3143 return;
3144 }
3145
3146 // Small trivially copyable types are cheap to copy. Do not emit the
3147 // diagnostic for these instances. 64 bytes is a common size of a cache line.
3148 // (The function `getTypeSize` returns the size in bits.)
3149 ASTContext &Ctx = SemaRef.Context;
3150 if (Ctx.getTypeSize(VariableType) <= 64 * 8 &&
3151 (VariableType.isTriviallyCopyableType(Ctx) ||
3152 hasTrivialABIAttr(VariableType)))
3153 return;
3154
3155 // Suggest changing from a const variable to a const reference variable
3156 // if doing so will prevent a copy.
3157 SemaRef.Diag(VD->getLocation(), diag::warn_for_range_copy)
3158 << VD << VariableType;
3159 SemaRef.Diag(VD->getBeginLoc(), diag::note_use_reference_type)
3160 << SemaRef.Context.getLValueReferenceType(VariableType)
3161 << VD->getSourceRange()
3162 << FixItHint::CreateInsertion(VD->getLocation(), "&");
3163 }
3164
3165 /// DiagnoseForRangeVariableCopies - Diagnose three cases and fixes for them.
3166 /// 1) for (const foo &x : foos) where foos only returns a copy. Suggest
3167 /// using "const foo x" to show that a copy is made
3168 /// 2) for (const bar &x : foos) where bar is a temporary initialized by bar.
3169 /// Suggest either "const bar x" to keep the copying or "const foo& x" to
3170 /// prevent the copy.
3171 /// 3) for (const foo x : foos) where x is constructed from a reference foo.
3172 /// Suggest "const foo &x" to prevent the copy.
DiagnoseForRangeVariableCopies(Sema & SemaRef,const CXXForRangeStmt * ForStmt)3173 static void DiagnoseForRangeVariableCopies(Sema &SemaRef,
3174 const CXXForRangeStmt *ForStmt) {
3175 if (SemaRef.inTemplateInstantiation())
3176 return;
3177
3178 if (SemaRef.Diags.isIgnored(
3179 diag::warn_for_range_const_ref_binds_temp_built_from_ref,
3180 ForStmt->getBeginLoc()) &&
3181 SemaRef.Diags.isIgnored(diag::warn_for_range_ref_binds_ret_temp,
3182 ForStmt->getBeginLoc()) &&
3183 SemaRef.Diags.isIgnored(diag::warn_for_range_copy,
3184 ForStmt->getBeginLoc())) {
3185 return;
3186 }
3187
3188 const VarDecl *VD = ForStmt->getLoopVariable();
3189 if (!VD)
3190 return;
3191
3192 QualType VariableType = VD->getType();
3193
3194 if (VariableType->isIncompleteType())
3195 return;
3196
3197 const Expr *InitExpr = VD->getInit();
3198 if (!InitExpr)
3199 return;
3200
3201 if (InitExpr->getExprLoc().isMacroID())
3202 return;
3203
3204 if (VariableType->isReferenceType()) {
3205 DiagnoseForRangeReferenceVariableCopies(SemaRef, VD,
3206 ForStmt->getRangeInit()->getType());
3207 } else if (VariableType.isConstQualified()) {
3208 DiagnoseForRangeConstVariableCopies(SemaRef, VD);
3209 }
3210 }
3211
3212 /// FinishCXXForRangeStmt - Attach the body to a C++0x for-range statement.
3213 /// This is a separate step from ActOnCXXForRangeStmt because analysis of the
3214 /// body cannot be performed until after the type of the range variable is
3215 /// determined.
FinishCXXForRangeStmt(Stmt * S,Stmt * B)3216 StmtResult Sema::FinishCXXForRangeStmt(Stmt *S, Stmt *B) {
3217 if (!S || !B)
3218 return StmtError();
3219
3220 if (isa<ObjCForCollectionStmt>(S))
3221 return FinishObjCForCollectionStmt(S, B);
3222
3223 CXXForRangeStmt *ForStmt = cast<CXXForRangeStmt>(S);
3224 ForStmt->setBody(B);
3225
3226 DiagnoseEmptyStmtBody(ForStmt->getRParenLoc(), B,
3227 diag::warn_empty_range_based_for_body);
3228
3229 DiagnoseForRangeVariableCopies(*this, ForStmt);
3230
3231 return S;
3232 }
3233
ActOnGotoStmt(SourceLocation GotoLoc,SourceLocation LabelLoc,LabelDecl * TheDecl)3234 StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc,
3235 SourceLocation LabelLoc,
3236 LabelDecl *TheDecl) {
3237 setFunctionHasBranchIntoScope();
3238 TheDecl->markUsed(Context);
3239 return new (Context) GotoStmt(TheDecl, GotoLoc, LabelLoc);
3240 }
3241
3242 StmtResult
ActOnIndirectGotoStmt(SourceLocation GotoLoc,SourceLocation StarLoc,Expr * E)3243 Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
3244 Expr *E) {
3245 // Convert operand to void*
3246 if (!E->isTypeDependent()) {
3247 QualType ETy = E->getType();
3248 QualType DestTy = Context.getPointerType(Context.VoidTy.withConst());
3249 ExprResult ExprRes = E;
3250 AssignConvertType ConvTy =
3251 CheckSingleAssignmentConstraints(DestTy, ExprRes);
3252 if (ExprRes.isInvalid())
3253 return StmtError();
3254 E = ExprRes.get();
3255 if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing))
3256 return StmtError();
3257 }
3258
3259 ExprResult ExprRes = ActOnFinishFullExpr(E, /*DiscardedValue*/ false);
3260 if (ExprRes.isInvalid())
3261 return StmtError();
3262 E = ExprRes.get();
3263
3264 setFunctionHasIndirectGoto();
3265
3266 return new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E);
3267 }
3268
CheckJumpOutOfSEHFinally(Sema & S,SourceLocation Loc,const Scope & DestScope)3269 static void CheckJumpOutOfSEHFinally(Sema &S, SourceLocation Loc,
3270 const Scope &DestScope) {
3271 if (!S.CurrentSEHFinally.empty() &&
3272 DestScope.Contains(*S.CurrentSEHFinally.back())) {
3273 S.Diag(Loc, diag::warn_jump_out_of_seh_finally);
3274 }
3275 }
3276
3277 StmtResult
ActOnContinueStmt(SourceLocation ContinueLoc,Scope * CurScope)3278 Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
3279 Scope *S = CurScope->getContinueParent();
3280 if (!S) {
3281 // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
3282 return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
3283 }
3284 if (S->getFlags() & Scope::ConditionVarScope) {
3285 // We cannot 'continue;' from within a statement expression in the
3286 // initializer of a condition variable because we would jump past the
3287 // initialization of that variable.
3288 return StmtError(Diag(ContinueLoc, diag::err_continue_from_cond_var_init));
3289 }
3290 CheckJumpOutOfSEHFinally(*this, ContinueLoc, *S);
3291
3292 return new (Context) ContinueStmt(ContinueLoc);
3293 }
3294
3295 StmtResult
ActOnBreakStmt(SourceLocation BreakLoc,Scope * CurScope)3296 Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
3297 Scope *S = CurScope->getBreakParent();
3298 if (!S) {
3299 // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
3300 return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
3301 }
3302 if (S->isOpenMPLoopScope())
3303 return StmtError(Diag(BreakLoc, diag::err_omp_loop_cannot_use_stmt)
3304 << "break");
3305 CheckJumpOutOfSEHFinally(*this, BreakLoc, *S);
3306
3307 return new (Context) BreakStmt(BreakLoc);
3308 }
3309
3310 /// Determine whether the given expression is a candidate for
3311 /// copy elision in either a return statement or a throw expression.
3312 ///
3313 /// \param ReturnType If we're determining the copy elision candidate for
3314 /// a return statement, this is the return type of the function. If we're
3315 /// determining the copy elision candidate for a throw expression, this will
3316 /// be a NULL type.
3317 ///
3318 /// \param E The expression being returned from the function or block, or
3319 /// being thrown.
3320 ///
3321 /// \param CESK Whether we allow function parameters or
3322 /// id-expressions that could be moved out of the function to be considered NRVO
3323 /// candidates. C++ prohibits these for NRVO itself, but we re-use this logic to
3324 /// determine whether we should try to move as part of a return or throw (which
3325 /// does allow function parameters).
3326 ///
3327 /// \returns The NRVO candidate variable, if the return statement may use the
3328 /// NRVO, or NULL if there is no such candidate.
getCopyElisionCandidate(QualType ReturnType,Expr * E,CopyElisionSemanticsKind CESK)3329 VarDecl *Sema::getCopyElisionCandidate(QualType ReturnType, Expr *E,
3330 CopyElisionSemanticsKind CESK) {
3331 // - in a return statement in a function [where] ...
3332 // ... the expression is the name of a non-volatile automatic object ...
3333 DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E->IgnoreParens());
3334 if (!DR || DR->refersToEnclosingVariableOrCapture())
3335 return nullptr;
3336 VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
3337 if (!VD)
3338 return nullptr;
3339
3340 if (isCopyElisionCandidate(ReturnType, VD, CESK))
3341 return VD;
3342 return nullptr;
3343 }
3344
isCopyElisionCandidate(QualType ReturnType,const VarDecl * VD,CopyElisionSemanticsKind CESK)3345 bool Sema::isCopyElisionCandidate(QualType ReturnType, const VarDecl *VD,
3346 CopyElisionSemanticsKind CESK) {
3347 QualType VDType = VD->getType();
3348 // - in a return statement in a function with ...
3349 // ... a class return type ...
3350 if (!ReturnType.isNull() && !ReturnType->isDependentType()) {
3351 if (!ReturnType->isRecordType())
3352 return false;
3353 // ... the same cv-unqualified type as the function return type ...
3354 // When considering moving this expression out, allow dissimilar types.
3355 if (!(CESK & CES_AllowDifferentTypes) && !VDType->isDependentType() &&
3356 !Context.hasSameUnqualifiedType(ReturnType, VDType))
3357 return false;
3358 }
3359
3360 // ...object (other than a function or catch-clause parameter)...
3361 if (VD->getKind() != Decl::Var &&
3362 !((CESK & CES_AllowParameters) && VD->getKind() == Decl::ParmVar))
3363 return false;
3364 if (!(CESK & CES_AllowExceptionVariables) && VD->isExceptionVariable())
3365 return false;
3366
3367 // ...automatic...
3368 if (!VD->hasLocalStorage()) return false;
3369
3370 // Return false if VD is a __block variable. We don't want to implicitly move
3371 // out of a __block variable during a return because we cannot assume the
3372 // variable will no longer be used.
3373 if (VD->hasAttr<BlocksAttr>())
3374 return false;
3375
3376 if (VDType->isObjectType()) {
3377 // C++17 [class.copy.elision]p3:
3378 // ...non-volatile automatic object...
3379 if (VDType.isVolatileQualified())
3380 return false;
3381 } else if (VDType->isRValueReferenceType()) {
3382 // C++20 [class.copy.elision]p3:
3383 // ...either a non-volatile object or an rvalue reference to a non-volatile object type...
3384 if (!(CESK & CES_AllowRValueReferenceType))
3385 return false;
3386 QualType VDReferencedType = VDType.getNonReferenceType();
3387 if (VDReferencedType.isVolatileQualified() || !VDReferencedType->isObjectType())
3388 return false;
3389 } else {
3390 return false;
3391 }
3392
3393 if (CESK & CES_AllowDifferentTypes)
3394 return true;
3395
3396 // Variables with higher required alignment than their type's ABI
3397 // alignment cannot use NRVO.
3398 if (!VDType->isDependentType() && VD->hasAttr<AlignedAttr>() &&
3399 Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VDType))
3400 return false;
3401
3402 return true;
3403 }
3404
3405 /// Try to perform the initialization of a potentially-movable value,
3406 /// which is the operand to a return or throw statement.
3407 ///
3408 /// This routine implements C++20 [class.copy.elision]p3, which attempts to
3409 /// treat returned lvalues as rvalues in certain cases (to prefer move
3410 /// construction), then falls back to treating them as lvalues if that failed.
3411 ///
3412 /// \param ConvertingConstructorsOnly If true, follow [class.copy.elision]p3 and
3413 /// reject resolutions that find non-constructors, such as derived-to-base
3414 /// conversions or `operator T()&&` member functions. If false, do consider such
3415 /// conversion sequences.
3416 ///
3417 /// \param Res We will fill this in if move-initialization was possible.
3418 /// If move-initialization is not possible, such that we must fall back to
3419 /// treating the operand as an lvalue, we will leave Res in its original
3420 /// invalid state.
3421 ///
3422 /// \returns Whether we need to do the second overload resolution. If the first
3423 /// overload resolution fails, or if the first overload resolution succeeds but
3424 /// the selected constructor/operator doesn't match the additional criteria, we
3425 /// need to do the second overload resolution.
TryMoveInitialization(Sema & S,const InitializedEntity & Entity,const VarDecl * NRVOCandidate,QualType ResultType,Expr * & Value,bool ConvertingConstructorsOnly,bool IsDiagnosticsCheck,ExprResult & Res)3426 static bool TryMoveInitialization(Sema &S, const InitializedEntity &Entity,
3427 const VarDecl *NRVOCandidate,
3428 QualType ResultType, Expr *&Value,
3429 bool ConvertingConstructorsOnly,
3430 bool IsDiagnosticsCheck, ExprResult &Res) {
3431 ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(),
3432 CK_NoOp, Value, VK_XValue, FPOptionsOverride());
3433
3434 Expr *InitExpr = &AsRvalue;
3435
3436 InitializationKind Kind = InitializationKind::CreateCopy(
3437 Value->getBeginLoc(), Value->getBeginLoc());
3438
3439 InitializationSequence Seq(S, Entity, Kind, InitExpr);
3440
3441 bool NeedSecondOverloadResolution = true;
3442 if (!Seq &&
3443 (IsDiagnosticsCheck || Seq.getFailedOverloadResult() != OR_Deleted)) {
3444 return NeedSecondOverloadResolution;
3445 }
3446
3447 for (const InitializationSequence::Step &Step : Seq.steps()) {
3448 if (Step.Kind != InitializationSequence::SK_ConstructorInitialization &&
3449 Step.Kind != InitializationSequence::SK_UserConversion)
3450 continue;
3451
3452 FunctionDecl *FD = Step.Function.Function;
3453 if (ConvertingConstructorsOnly) {
3454 if (isa<CXXConstructorDecl>(FD)) {
3455 // C++11 [class.copy]p32:
3456 // C++14 [class.copy]p32:
3457 // C++17 [class.copy.elision]p3:
3458 // [...] if the type of the first parameter of the selected constructor
3459 // is not an rvalue reference to the object's type (possibly
3460 // cv-qualified), overload resolution is performed again, considering
3461 // the object as an lvalue.
3462 const RValueReferenceType *RRefType =
3463 FD->getParamDecl(0)->getType()->getAs<RValueReferenceType>();
3464 if (!RRefType)
3465 break;
3466 if (!S.Context.hasSameUnqualifiedType(RRefType->getPointeeType(),
3467 NRVOCandidate->getType()))
3468 break;
3469 } else {
3470 continue;
3471 }
3472 } else {
3473 if (isa<CXXConstructorDecl>(FD)) {
3474 // Check that overload resolution selected a constructor taking an
3475 // rvalue reference. If it selected an lvalue reference, then we
3476 // didn't need to cast this thing to an rvalue in the first place.
3477 if (IsDiagnosticsCheck &&
3478 !isa<RValueReferenceType>(FD->getParamDecl(0)->getType()))
3479 break;
3480 } else if (isa<CXXMethodDecl>(FD)) {
3481 // Check that overload resolution selected a conversion operator
3482 // taking an rvalue reference.
3483 if (cast<CXXMethodDecl>(FD)->getRefQualifier() != RQ_RValue)
3484 break;
3485 } else {
3486 continue;
3487 }
3488 }
3489
3490 NeedSecondOverloadResolution = false;
3491 // Promote "AsRvalue" to the heap, since we now need this
3492 // expression node to persist.
3493 Value =
3494 ImplicitCastExpr::Create(S.Context, Value->getType(), CK_NoOp, Value,
3495 nullptr, VK_XValue, FPOptionsOverride());
3496
3497 // Complete type-checking the initialization of the return type
3498 // using the constructor we found.
3499 Res = Seq.Perform(S, Entity, Kind, Value);
3500 }
3501
3502 return NeedSecondOverloadResolution;
3503 }
3504
3505 /// Perform the initialization of a potentially-movable value, which
3506 /// is the result of return value.
3507 ///
3508 /// This routine implements C++20 [class.copy.elision]p3, which attempts to
3509 /// treat returned lvalues as rvalues in certain cases (to prefer move
3510 /// construction), then falls back to treating them as lvalues if that failed.
PerformMoveOrCopyInitialization(const InitializedEntity & Entity,const VarDecl * NRVOCandidate,QualType ResultType,Expr * Value,bool AllowNRVO)3511 ExprResult Sema::PerformMoveOrCopyInitialization(
3512 const InitializedEntity &Entity, const VarDecl *NRVOCandidate,
3513 QualType ResultType, Expr *Value, bool AllowNRVO) {
3514 ExprResult Res = ExprError();
3515 bool NeedSecondOverloadResolution = true;
3516
3517 if (AllowNRVO) {
3518 CopyElisionSemanticsKind CESK = CES_Strict;
3519 if (getLangOpts().CPlusPlus20) {
3520 CESK = CES_ImplicitlyMovableCXX20;
3521 } else if (getLangOpts().CPlusPlus11) {
3522 CESK = CES_ImplicitlyMovableCXX11CXX14CXX17;
3523 }
3524
3525 if (!NRVOCandidate) {
3526 NRVOCandidate = getCopyElisionCandidate(ResultType, Value, CESK);
3527 }
3528
3529 if (NRVOCandidate) {
3530 NeedSecondOverloadResolution =
3531 TryMoveInitialization(*this, Entity, NRVOCandidate, ResultType, Value,
3532 !getLangOpts().CPlusPlus20, false, Res);
3533 }
3534
3535 if (!getLangOpts().CPlusPlus20 && NeedSecondOverloadResolution &&
3536 !getDiagnostics().isIgnored(diag::warn_return_std_move,
3537 Value->getExprLoc())) {
3538 const VarDecl *FakeNRVOCandidate = getCopyElisionCandidate(
3539 QualType(), Value, CES_ImplicitlyMovableCXX20);
3540 if (FakeNRVOCandidate) {
3541 QualType QT = FakeNRVOCandidate->getType();
3542 if (QT->isLValueReferenceType()) {
3543 // Adding 'std::move' around an lvalue reference variable's name is
3544 // dangerous. Don't suggest it.
3545 } else if (QT.getNonReferenceType()
3546 .getUnqualifiedType()
3547 .isTriviallyCopyableType(Context)) {
3548 // Adding 'std::move' around a trivially copyable variable is probably
3549 // pointless. Don't suggest it.
3550 } else {
3551 ExprResult FakeRes = ExprError();
3552 Expr *FakeValue = Value;
3553 TryMoveInitialization(*this, Entity, FakeNRVOCandidate, ResultType,
3554 FakeValue, false, true, FakeRes);
3555 if (!FakeRes.isInvalid()) {
3556 bool IsThrow =
3557 (Entity.getKind() == InitializedEntity::EK_Exception);
3558 SmallString<32> Str;
3559 Str += "std::move(";
3560 Str += FakeNRVOCandidate->getDeclName().getAsString();
3561 Str += ")";
3562 Diag(Value->getExprLoc(), diag::warn_return_std_move)
3563 << Value->getSourceRange()
3564 << FakeNRVOCandidate->getDeclName() << IsThrow;
3565 Diag(Value->getExprLoc(), diag::note_add_std_move)
3566 << FixItHint::CreateReplacement(Value->getSourceRange(), Str);
3567 }
3568 }
3569 }
3570 }
3571 }
3572
3573 // Either we didn't meet the criteria for treating an lvalue as an rvalue,
3574 // above, or overload resolution failed. Either way, we need to try
3575 // (again) now with the return value expression as written.
3576 if (NeedSecondOverloadResolution)
3577 Res = PerformCopyInitialization(Entity, SourceLocation(), Value);
3578
3579 return Res;
3580 }
3581
3582 /// Determine whether the declared return type of the specified function
3583 /// contains 'auto'.
hasDeducedReturnType(FunctionDecl * FD)3584 static bool hasDeducedReturnType(FunctionDecl *FD) {
3585 const FunctionProtoType *FPT =
3586 FD->getTypeSourceInfo()->getType()->castAs<FunctionProtoType>();
3587 return FPT->getReturnType()->isUndeducedType();
3588 }
3589
3590 /// ActOnCapScopeReturnStmt - Utility routine to type-check return statements
3591 /// for capturing scopes.
3592 ///
3593 StmtResult
ActOnCapScopeReturnStmt(SourceLocation ReturnLoc,Expr * RetValExp)3594 Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
3595 // If this is the first return we've seen, infer the return type.
3596 // [expr.prim.lambda]p4 in C++11; block literals follow the same rules.
3597 CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
3598 QualType FnRetType = CurCap->ReturnType;
3599 LambdaScopeInfo *CurLambda = dyn_cast<LambdaScopeInfo>(CurCap);
3600 bool HasDeducedReturnType =
3601 CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
3602
3603 if (ExprEvalContexts.back().Context ==
3604 ExpressionEvaluationContext::DiscardedStatement &&
3605 (HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
3606 if (RetValExp) {
3607 ExprResult ER =
3608 ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3609 if (ER.isInvalid())
3610 return StmtError();
3611 RetValExp = ER.get();
3612 }
3613 return ReturnStmt::Create(Context, ReturnLoc, RetValExp,
3614 /* NRVOCandidate=*/nullptr);
3615 }
3616
3617 if (HasDeducedReturnType) {
3618 FunctionDecl *FD = CurLambda->CallOperator;
3619 // If we've already decided this lambda is invalid, e.g. because
3620 // we saw a `return` whose expression had an error, don't keep
3621 // trying to deduce its return type.
3622 if (FD->isInvalidDecl())
3623 return StmtError();
3624 // In C++1y, the return type may involve 'auto'.
3625 // FIXME: Blocks might have a return type of 'auto' explicitly specified.
3626 if (CurCap->ReturnType.isNull())
3627 CurCap->ReturnType = FD->getReturnType();
3628
3629 AutoType *AT = CurCap->ReturnType->getContainedAutoType();
3630 assert(AT && "lost auto type from lambda return type");
3631 if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
3632 FD->setInvalidDecl();
3633 // FIXME: preserve the ill-formed return expression.
3634 return StmtError();
3635 }
3636 CurCap->ReturnType = FnRetType = FD->getReturnType();
3637 } else if (CurCap->HasImplicitReturnType) {
3638 // For blocks/lambdas with implicit return types, we check each return
3639 // statement individually, and deduce the common return type when the block
3640 // or lambda is completed.
3641 // FIXME: Fold this into the 'auto' codepath above.
3642 if (RetValExp && !isa<InitListExpr>(RetValExp)) {
3643 ExprResult Result = DefaultFunctionArrayLvalueConversion(RetValExp);
3644 if (Result.isInvalid())
3645 return StmtError();
3646 RetValExp = Result.get();
3647
3648 // DR1048: even prior to C++14, we should use the 'auto' deduction rules
3649 // when deducing a return type for a lambda-expression (or by extension
3650 // for a block). These rules differ from the stated C++11 rules only in
3651 // that they remove top-level cv-qualifiers.
3652 if (!CurContext->isDependentContext())
3653 FnRetType = RetValExp->getType().getUnqualifiedType();
3654 else
3655 FnRetType = CurCap->ReturnType = Context.DependentTy;
3656 } else {
3657 if (RetValExp) {
3658 // C++11 [expr.lambda.prim]p4 bans inferring the result from an
3659 // initializer list, because it is not an expression (even
3660 // though we represent it as one). We still deduce 'void'.
3661 Diag(ReturnLoc, diag::err_lambda_return_init_list)
3662 << RetValExp->getSourceRange();
3663 }
3664
3665 FnRetType = Context.VoidTy;
3666 }
3667
3668 // Although we'll properly infer the type of the block once it's completed,
3669 // make sure we provide a return type now for better error recovery.
3670 if (CurCap->ReturnType.isNull())
3671 CurCap->ReturnType = FnRetType;
3672 }
3673 assert(!FnRetType.isNull());
3674
3675 if (auto *CurBlock = dyn_cast<BlockScopeInfo>(CurCap)) {
3676 if (CurBlock->FunctionType->castAs<FunctionType>()->getNoReturnAttr()) {
3677 Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr);
3678 return StmtError();
3679 }
3680 } else if (auto *CurRegion = dyn_cast<CapturedRegionScopeInfo>(CurCap)) {
3681 Diag(ReturnLoc, diag::err_return_in_captured_stmt) << CurRegion->getRegionName();
3682 return StmtError();
3683 } else {
3684 assert(CurLambda && "unknown kind of captured scope");
3685 if (CurLambda->CallOperator->getType()
3686 ->castAs<FunctionType>()
3687 ->getNoReturnAttr()) {
3688 Diag(ReturnLoc, diag::err_noreturn_lambda_has_return_expr);
3689 return StmtError();
3690 }
3691 }
3692
3693 // Otherwise, verify that this result type matches the previous one. We are
3694 // pickier with blocks than for normal functions because we don't have GCC
3695 // compatibility to worry about here.
3696 const VarDecl *NRVOCandidate = nullptr;
3697 if (FnRetType->isDependentType()) {
3698 // Delay processing for now. TODO: there are lots of dependent
3699 // types we can conclusively prove aren't void.
3700 } else if (FnRetType->isVoidType()) {
3701 if (RetValExp && !isa<InitListExpr>(RetValExp) &&
3702 !(getLangOpts().CPlusPlus &&
3703 (RetValExp->isTypeDependent() ||
3704 RetValExp->getType()->isVoidType()))) {
3705 if (!getLangOpts().CPlusPlus &&
3706 RetValExp->getType()->isVoidType())
3707 Diag(ReturnLoc, diag::ext_return_has_void_expr) << "literal" << 2;
3708 else {
3709 Diag(ReturnLoc, diag::err_return_block_has_expr);
3710 RetValExp = nullptr;
3711 }
3712 }
3713 } else if (!RetValExp) {
3714 return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
3715 } else if (!RetValExp->isTypeDependent()) {
3716 // we have a non-void block with an expression, continue checking
3717
3718 // C99 6.8.6.4p3(136): The return statement is not an assignment. The
3719 // overlap restriction of subclause 6.5.16.1 does not apply to the case of
3720 // function return.
3721
3722 // In C++ the return statement is handled via a copy initialization.
3723 // the C version of which boils down to CheckSingleAssignmentConstraints.
3724 NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
3725 InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
3726 FnRetType,
3727 NRVOCandidate != nullptr);
3728 ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
3729 FnRetType, RetValExp);
3730 if (Res.isInvalid()) {
3731 // FIXME: Cleanup temporaries here, anyway?
3732 return StmtError();
3733 }
3734 RetValExp = Res.get();
3735 CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc);
3736 } else {
3737 NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
3738 }
3739
3740 if (RetValExp) {
3741 ExprResult ER =
3742 ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3743 if (ER.isInvalid())
3744 return StmtError();
3745 RetValExp = ER.get();
3746 }
3747 auto *Result =
3748 ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate);
3749
3750 // If we need to check for the named return value optimization,
3751 // or if we need to infer the return type,
3752 // save the return statement in our scope for later processing.
3753 if (CurCap->HasImplicitReturnType || NRVOCandidate)
3754 FunctionScopes.back()->Returns.push_back(Result);
3755
3756 if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
3757 FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
3758
3759 return Result;
3760 }
3761
3762 namespace {
3763 /// Marks all typedefs in all local classes in a type referenced.
3764 ///
3765 /// In a function like
3766 /// auto f() {
3767 /// struct S { typedef int a; };
3768 /// return S();
3769 /// }
3770 ///
3771 /// the local type escapes and could be referenced in some TUs but not in
3772 /// others. Pretend that all local typedefs are always referenced, to not warn
3773 /// on this. This isn't necessary if f has internal linkage, or the typedef
3774 /// is private.
3775 class LocalTypedefNameReferencer
3776 : public RecursiveASTVisitor<LocalTypedefNameReferencer> {
3777 public:
LocalTypedefNameReferencer(Sema & S)3778 LocalTypedefNameReferencer(Sema &S) : S(S) {}
3779 bool VisitRecordType(const RecordType *RT);
3780 private:
3781 Sema &S;
3782 };
VisitRecordType(const RecordType * RT)3783 bool LocalTypedefNameReferencer::VisitRecordType(const RecordType *RT) {
3784 auto *R = dyn_cast<CXXRecordDecl>(RT->getDecl());
3785 if (!R || !R->isLocalClass() || !R->isLocalClass()->isExternallyVisible() ||
3786 R->isDependentType())
3787 return true;
3788 for (auto *TmpD : R->decls())
3789 if (auto *T = dyn_cast<TypedefNameDecl>(TmpD))
3790 if (T->getAccess() != AS_private || R->hasFriends())
3791 S.MarkAnyDeclReferenced(T->getLocation(), T, /*OdrUse=*/false);
3792 return true;
3793 }
3794 }
3795
getReturnTypeLoc(FunctionDecl * FD) const3796 TypeLoc Sema::getReturnTypeLoc(FunctionDecl *FD) const {
3797 return FD->getTypeSourceInfo()
3798 ->getTypeLoc()
3799 .getAsAdjusted<FunctionProtoTypeLoc>()
3800 .getReturnLoc();
3801 }
3802
3803 /// Deduce the return type for a function from a returned expression, per
3804 /// C++1y [dcl.spec.auto]p6.
DeduceFunctionTypeFromReturnExpr(FunctionDecl * FD,SourceLocation ReturnLoc,Expr * & RetExpr,AutoType * AT)3805 bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
3806 SourceLocation ReturnLoc,
3807 Expr *&RetExpr,
3808 AutoType *AT) {
3809 // If this is the conversion function for a lambda, we choose to deduce it
3810 // type from the corresponding call operator, not from the synthesized return
3811 // statement within it. See Sema::DeduceReturnType.
3812 if (isLambdaConversionOperator(FD))
3813 return false;
3814
3815 TypeLoc OrigResultType = getReturnTypeLoc(FD);
3816 QualType Deduced;
3817
3818 if (RetExpr && isa<InitListExpr>(RetExpr)) {
3819 // If the deduction is for a return statement and the initializer is
3820 // a braced-init-list, the program is ill-formed.
3821 Diag(RetExpr->getExprLoc(),
3822 getCurLambda() ? diag::err_lambda_return_init_list
3823 : diag::err_auto_fn_return_init_list)
3824 << RetExpr->getSourceRange();
3825 return true;
3826 }
3827
3828 if (FD->isDependentContext()) {
3829 // C++1y [dcl.spec.auto]p12:
3830 // Return type deduction [...] occurs when the definition is
3831 // instantiated even if the function body contains a return
3832 // statement with a non-type-dependent operand.
3833 assert(AT->isDeduced() && "should have deduced to dependent type");
3834 return false;
3835 }
3836
3837 if (RetExpr) {
3838 // Otherwise, [...] deduce a value for U using the rules of template
3839 // argument deduction.
3840 DeduceAutoResult DAR = DeduceAutoType(OrigResultType, RetExpr, Deduced);
3841
3842 if (DAR == DAR_Failed && !FD->isInvalidDecl())
3843 Diag(RetExpr->getExprLoc(), diag::err_auto_fn_deduction_failure)
3844 << OrigResultType.getType() << RetExpr->getType();
3845
3846 if (DAR != DAR_Succeeded)
3847 return true;
3848
3849 // If a local type is part of the returned type, mark its fields as
3850 // referenced.
3851 LocalTypedefNameReferencer Referencer(*this);
3852 Referencer.TraverseType(RetExpr->getType());
3853 } else {
3854 // In the case of a return with no operand, the initializer is considered
3855 // to be void().
3856 //
3857 // Deduction here can only succeed if the return type is exactly 'cv auto'
3858 // or 'decltype(auto)', so just check for that case directly.
3859 if (!OrigResultType.getType()->getAs<AutoType>()) {
3860 Diag(ReturnLoc, diag::err_auto_fn_return_void_but_not_auto)
3861 << OrigResultType.getType();
3862 return true;
3863 }
3864 // We always deduce U = void in this case.
3865 Deduced = SubstAutoType(OrigResultType.getType(), Context.VoidTy);
3866 if (Deduced.isNull())
3867 return true;
3868 }
3869
3870 // CUDA: Kernel function must have 'void' return type.
3871 if (getLangOpts().CUDA)
3872 if (FD->hasAttr<CUDAGlobalAttr>() && !Deduced->isVoidType()) {
3873 Diag(FD->getLocation(), diag::err_kern_type_not_void_return)
3874 << FD->getType() << FD->getSourceRange();
3875 return true;
3876 }
3877
3878 // If a function with a declared return type that contains a placeholder type
3879 // has multiple return statements, the return type is deduced for each return
3880 // statement. [...] if the type deduced is not the same in each deduction,
3881 // the program is ill-formed.
3882 QualType DeducedT = AT->getDeducedType();
3883 if (!DeducedT.isNull() && !FD->isInvalidDecl()) {
3884 AutoType *NewAT = Deduced->getContainedAutoType();
3885 // It is possible that NewAT->getDeducedType() is null. When that happens,
3886 // we should not crash, instead we ignore this deduction.
3887 if (NewAT->getDeducedType().isNull())
3888 return false;
3889
3890 CanQualType OldDeducedType = Context.getCanonicalFunctionResultType(
3891 DeducedT);
3892 CanQualType NewDeducedType = Context.getCanonicalFunctionResultType(
3893 NewAT->getDeducedType());
3894 if (!FD->isDependentContext() && OldDeducedType != NewDeducedType) {
3895 const LambdaScopeInfo *LambdaSI = getCurLambda();
3896 if (LambdaSI && LambdaSI->HasImplicitReturnType) {
3897 Diag(ReturnLoc, diag::err_typecheck_missing_return_type_incompatible)
3898 << NewAT->getDeducedType() << DeducedT
3899 << true /*IsLambda*/;
3900 } else {
3901 Diag(ReturnLoc, diag::err_auto_fn_different_deductions)
3902 << (AT->isDecltypeAuto() ? 1 : 0)
3903 << NewAT->getDeducedType() << DeducedT;
3904 }
3905 return true;
3906 }
3907 } else if (!FD->isInvalidDecl()) {
3908 // Update all declarations of the function to have the deduced return type.
3909 Context.adjustDeducedFunctionResultType(FD, Deduced);
3910 }
3911
3912 return false;
3913 }
3914
3915 StmtResult
ActOnReturnStmt(SourceLocation ReturnLoc,Expr * RetValExp,Scope * CurScope)3916 Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
3917 Scope *CurScope) {
3918 // Correct typos, in case the containing function returns 'auto' and
3919 // RetValExp should determine the deduced type.
3920 ExprResult RetVal = CorrectDelayedTyposInExpr(
3921 RetValExp, nullptr, /*RecoverUncorrectedTypos=*/true);
3922 if (RetVal.isInvalid())
3923 return StmtError();
3924 StmtResult R = BuildReturnStmt(ReturnLoc, RetVal.get());
3925 if (R.isInvalid() || ExprEvalContexts.back().Context ==
3926 ExpressionEvaluationContext::DiscardedStatement)
3927 return R;
3928
3929 if (VarDecl *VD =
3930 const_cast<VarDecl*>(cast<ReturnStmt>(R.get())->getNRVOCandidate())) {
3931 CurScope->addNRVOCandidate(VD);
3932 } else {
3933 CurScope->setNoNRVO();
3934 }
3935
3936 CheckJumpOutOfSEHFinally(*this, ReturnLoc, *CurScope->getFnParent());
3937
3938 return R;
3939 }
3940
BuildReturnStmt(SourceLocation ReturnLoc,Expr * RetValExp)3941 StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
3942 // Check for unexpanded parameter packs.
3943 if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp))
3944 return StmtError();
3945
3946 if (isa<CapturingScopeInfo>(getCurFunction()))
3947 return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp);
3948
3949 QualType FnRetType;
3950 QualType RelatedRetType;
3951 const AttrVec *Attrs = nullptr;
3952 bool isObjCMethod = false;
3953
3954 if (const FunctionDecl *FD = getCurFunctionDecl()) {
3955 FnRetType = FD->getReturnType();
3956 if (FD->hasAttrs())
3957 Attrs = &FD->getAttrs();
3958 if (FD->isNoReturn())
3959 Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr) << FD;
3960 if (FD->isMain() && RetValExp)
3961 if (isa<CXXBoolLiteralExpr>(RetValExp))
3962 Diag(ReturnLoc, diag::warn_main_returns_bool_literal)
3963 << RetValExp->getSourceRange();
3964 if (FD->hasAttr<CmseNSEntryAttr>() && RetValExp) {
3965 if (const auto *RT = dyn_cast<RecordType>(FnRetType.getCanonicalType())) {
3966 if (RT->getDecl()->isOrContainsUnion())
3967 Diag(RetValExp->getBeginLoc(), diag::warn_cmse_nonsecure_union) << 1;
3968 }
3969 }
3970 } else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
3971 FnRetType = MD->getReturnType();
3972 isObjCMethod = true;
3973 if (MD->hasAttrs())
3974 Attrs = &MD->getAttrs();
3975 if (MD->hasRelatedResultType() && MD->getClassInterface()) {
3976 // In the implementation of a method with a related return type, the
3977 // type used to type-check the validity of return statements within the
3978 // method body is a pointer to the type of the class being implemented.
3979 RelatedRetType = Context.getObjCInterfaceType(MD->getClassInterface());
3980 RelatedRetType = Context.getObjCObjectPointerType(RelatedRetType);
3981 }
3982 } else // If we don't have a function/method context, bail.
3983 return StmtError();
3984
3985 // C++1z: discarded return statements are not considered when deducing a
3986 // return type.
3987 if (ExprEvalContexts.back().Context ==
3988 ExpressionEvaluationContext::DiscardedStatement &&
3989 FnRetType->getContainedAutoType()) {
3990 if (RetValExp) {
3991 ExprResult ER =
3992 ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
3993 if (ER.isInvalid())
3994 return StmtError();
3995 RetValExp = ER.get();
3996 }
3997 return ReturnStmt::Create(Context, ReturnLoc, RetValExp,
3998 /* NRVOCandidate=*/nullptr);
3999 }
4000
4001 // FIXME: Add a flag to the ScopeInfo to indicate whether we're performing
4002 // deduction.
4003 if (getLangOpts().CPlusPlus14) {
4004 if (AutoType *AT = FnRetType->getContainedAutoType()) {
4005 FunctionDecl *FD = cast<FunctionDecl>(CurContext);
4006 // If we've already decided this function is invalid, e.g. because
4007 // we saw a `return` whose expression had an error, don't keep
4008 // trying to deduce its return type.
4009 if (FD->isInvalidDecl())
4010 return StmtError();
4011 if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) {
4012 FD->setInvalidDecl();
4013 return StmtError();
4014 } else {
4015 FnRetType = FD->getReturnType();
4016 }
4017 }
4018 }
4019
4020 bool HasDependentReturnType = FnRetType->isDependentType();
4021
4022 ReturnStmt *Result = nullptr;
4023 if (FnRetType->isVoidType()) {
4024 if (RetValExp) {
4025 if (isa<InitListExpr>(RetValExp)) {
4026 // We simply never allow init lists as the return value of void
4027 // functions. This is compatible because this was never allowed before,
4028 // so there's no legacy code to deal with.
4029 NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4030 int FunctionKind = 0;
4031 if (isa<ObjCMethodDecl>(CurDecl))
4032 FunctionKind = 1;
4033 else if (isa<CXXConstructorDecl>(CurDecl))
4034 FunctionKind = 2;
4035 else if (isa<CXXDestructorDecl>(CurDecl))
4036 FunctionKind = 3;
4037
4038 Diag(ReturnLoc, diag::err_return_init_list)
4039 << CurDecl << FunctionKind << RetValExp->getSourceRange();
4040
4041 // Drop the expression.
4042 RetValExp = nullptr;
4043 } else if (!RetValExp->isTypeDependent()) {
4044 // C99 6.8.6.4p1 (ext_ since GCC warns)
4045 unsigned D = diag::ext_return_has_expr;
4046 if (RetValExp->getType()->isVoidType()) {
4047 NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4048 if (isa<CXXConstructorDecl>(CurDecl) ||
4049 isa<CXXDestructorDecl>(CurDecl))
4050 D = diag::err_ctor_dtor_returns_void;
4051 else
4052 D = diag::ext_return_has_void_expr;
4053 }
4054 else {
4055 ExprResult Result = RetValExp;
4056 Result = IgnoredValueConversions(Result.get());
4057 if (Result.isInvalid())
4058 return StmtError();
4059 RetValExp = Result.get();
4060 RetValExp = ImpCastExprToType(RetValExp,
4061 Context.VoidTy, CK_ToVoid).get();
4062 }
4063 // return of void in constructor/destructor is illegal in C++.
4064 if (D == diag::err_ctor_dtor_returns_void) {
4065 NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4066 Diag(ReturnLoc, D) << CurDecl << isa<CXXDestructorDecl>(CurDecl)
4067 << RetValExp->getSourceRange();
4068 }
4069 // return (some void expression); is legal in C++.
4070 else if (D != diag::ext_return_has_void_expr ||
4071 !getLangOpts().CPlusPlus) {
4072 NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
4073
4074 int FunctionKind = 0;
4075 if (isa<ObjCMethodDecl>(CurDecl))
4076 FunctionKind = 1;
4077 else if (isa<CXXConstructorDecl>(CurDecl))
4078 FunctionKind = 2;
4079 else if (isa<CXXDestructorDecl>(CurDecl))
4080 FunctionKind = 3;
4081
4082 Diag(ReturnLoc, D)
4083 << CurDecl << FunctionKind << RetValExp->getSourceRange();
4084 }
4085 }
4086
4087 if (RetValExp) {
4088 ExprResult ER =
4089 ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
4090 if (ER.isInvalid())
4091 return StmtError();
4092 RetValExp = ER.get();
4093 }
4094 }
4095
4096 Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp,
4097 /* NRVOCandidate=*/nullptr);
4098 } else if (!RetValExp && !HasDependentReturnType) {
4099 FunctionDecl *FD = getCurFunctionDecl();
4100
4101 if (getLangOpts().CPlusPlus11 && FD && FD->isConstexpr()) {
4102 // C++11 [stmt.return]p2
4103 Diag(ReturnLoc, diag::err_constexpr_return_missing_expr)
4104 << FD << FD->isConsteval();
4105 FD->setInvalidDecl();
4106 } else {
4107 // C99 6.8.6.4p1 (ext_ since GCC warns)
4108 // C90 6.6.6.4p4
4109 unsigned DiagID = getLangOpts().C99 ? diag::ext_return_missing_expr
4110 : diag::warn_return_missing_expr;
4111 // Note that at this point one of getCurFunctionDecl() or
4112 // getCurMethodDecl() must be non-null (see above).
4113 assert((getCurFunctionDecl() || getCurMethodDecl()) &&
4114 "Not in a FunctionDecl or ObjCMethodDecl?");
4115 bool IsMethod = FD == nullptr;
4116 const NamedDecl *ND =
4117 IsMethod ? cast<NamedDecl>(getCurMethodDecl()) : cast<NamedDecl>(FD);
4118 Diag(ReturnLoc, DiagID) << ND << IsMethod;
4119 }
4120
4121 Result = ReturnStmt::Create(Context, ReturnLoc, /* RetExpr=*/nullptr,
4122 /* NRVOCandidate=*/nullptr);
4123 } else {
4124 assert(RetValExp || HasDependentReturnType);
4125 const VarDecl *NRVOCandidate = nullptr;
4126
4127 QualType RetType = RelatedRetType.isNull() ? FnRetType : RelatedRetType;
4128
4129 // C99 6.8.6.4p3(136): The return statement is not an assignment. The
4130 // overlap restriction of subclause 6.5.16.1 does not apply to the case of
4131 // function return.
4132
4133 // In C++ the return statement is handled via a copy initialization,
4134 // the C version of which boils down to CheckSingleAssignmentConstraints.
4135 if (RetValExp)
4136 NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
4137 if (!HasDependentReturnType && !RetValExp->isTypeDependent()) {
4138 // we have a non-void function with an expression, continue checking
4139 InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
4140 RetType,
4141 NRVOCandidate != nullptr);
4142 ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
4143 RetType, RetValExp);
4144 if (Res.isInvalid()) {
4145 // FIXME: Clean up temporaries here anyway?
4146 return StmtError();
4147 }
4148 RetValExp = Res.getAs<Expr>();
4149
4150 // If we have a related result type, we need to implicitly
4151 // convert back to the formal result type. We can't pretend to
4152 // initialize the result again --- we might end double-retaining
4153 // --- so instead we initialize a notional temporary.
4154 if (!RelatedRetType.isNull()) {
4155 Entity = InitializedEntity::InitializeRelatedResult(getCurMethodDecl(),
4156 FnRetType);
4157 Res = PerformCopyInitialization(Entity, ReturnLoc, RetValExp);
4158 if (Res.isInvalid()) {
4159 // FIXME: Clean up temporaries here anyway?
4160 return StmtError();
4161 }
4162 RetValExp = Res.getAs<Expr>();
4163 }
4164
4165 CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc, isObjCMethod, Attrs,
4166 getCurFunctionDecl());
4167 }
4168
4169 if (RetValExp) {
4170 ExprResult ER =
4171 ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false);
4172 if (ER.isInvalid())
4173 return StmtError();
4174 RetValExp = ER.get();
4175 }
4176 Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate);
4177 }
4178
4179 // If we need to check for the named return value optimization, save the
4180 // return statement in our scope for later processing.
4181 if (Result->getNRVOCandidate())
4182 FunctionScopes.back()->Returns.push_back(Result);
4183
4184 if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
4185 FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
4186
4187 return Result;
4188 }
4189
4190 StmtResult
ActOnObjCAtCatchStmt(SourceLocation AtLoc,SourceLocation RParen,Decl * Parm,Stmt * Body)4191 Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
4192 SourceLocation RParen, Decl *Parm,
4193 Stmt *Body) {
4194 VarDecl *Var = cast_or_null<VarDecl>(Parm);
4195 if (Var && Var->isInvalidDecl())
4196 return StmtError();
4197
4198 return new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body);
4199 }
4200
4201 StmtResult
ActOnObjCAtFinallyStmt(SourceLocation AtLoc,Stmt * Body)4202 Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) {
4203 return new (Context) ObjCAtFinallyStmt(AtLoc, Body);
4204 }
4205
4206 StmtResult
ActOnObjCAtTryStmt(SourceLocation AtLoc,Stmt * Try,MultiStmtArg CatchStmts,Stmt * Finally)4207 Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
4208 MultiStmtArg CatchStmts, Stmt *Finally) {
4209 if (!getLangOpts().ObjCExceptions)
4210 Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@try";
4211
4212 setFunctionHasBranchProtectedScope();
4213 unsigned NumCatchStmts = CatchStmts.size();
4214 return ObjCAtTryStmt::Create(Context, AtLoc, Try, CatchStmts.data(),
4215 NumCatchStmts, Finally);
4216 }
4217
BuildObjCAtThrowStmt(SourceLocation AtLoc,Expr * Throw)4218 StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) {
4219 if (Throw) {
4220 ExprResult Result = DefaultLvalueConversion(Throw);
4221 if (Result.isInvalid())
4222 return StmtError();
4223
4224 Result = ActOnFinishFullExpr(Result.get(), /*DiscardedValue*/ false);
4225 if (Result.isInvalid())
4226 return StmtError();
4227 Throw = Result.get();
4228
4229 QualType ThrowType = Throw->getType();
4230 // Make sure the expression type is an ObjC pointer or "void *".
4231 if (!ThrowType->isDependentType() &&
4232 !ThrowType->isObjCObjectPointerType()) {
4233 const PointerType *PT = ThrowType->getAs<PointerType>();
4234 if (!PT || !PT->getPointeeType()->isVoidType())
4235 return StmtError(Diag(AtLoc, diag::err_objc_throw_expects_object)
4236 << Throw->getType() << Throw->getSourceRange());
4237 }
4238 }
4239
4240 return new (Context) ObjCAtThrowStmt(AtLoc, Throw);
4241 }
4242
4243 StmtResult
ActOnObjCAtThrowStmt(SourceLocation AtLoc,Expr * Throw,Scope * CurScope)4244 Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
4245 Scope *CurScope) {
4246 if (!getLangOpts().ObjCExceptions)
4247 Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@throw";
4248
4249 if (!Throw) {
4250 // @throw without an expression designates a rethrow (which must occur
4251 // in the context of an @catch clause).
4252 Scope *AtCatchParent = CurScope;
4253 while (AtCatchParent && !AtCatchParent->isAtCatchScope())
4254 AtCatchParent = AtCatchParent->getParent();
4255 if (!AtCatchParent)
4256 return StmtError(Diag(AtLoc, diag::err_rethrow_used_outside_catch));
4257 }
4258 return BuildObjCAtThrowStmt(AtLoc, Throw);
4259 }
4260
4261 ExprResult
ActOnObjCAtSynchronizedOperand(SourceLocation atLoc,Expr * operand)4262 Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
4263 ExprResult result = DefaultLvalueConversion(operand);
4264 if (result.isInvalid())
4265 return ExprError();
4266 operand = result.get();
4267
4268 // Make sure the expression type is an ObjC pointer or "void *".
4269 QualType type = operand->getType();
4270 if (!type->isDependentType() &&
4271 !type->isObjCObjectPointerType()) {
4272 const PointerType *pointerType = type->getAs<PointerType>();
4273 if (!pointerType || !pointerType->getPointeeType()->isVoidType()) {
4274 if (getLangOpts().CPlusPlus) {
4275 if (RequireCompleteType(atLoc, type,
4276 diag::err_incomplete_receiver_type))
4277 return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4278 << type << operand->getSourceRange();
4279
4280 ExprResult result = PerformContextuallyConvertToObjCPointer(operand);
4281 if (result.isInvalid())
4282 return ExprError();
4283 if (!result.isUsable())
4284 return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4285 << type << operand->getSourceRange();
4286
4287 operand = result.get();
4288 } else {
4289 return Diag(atLoc, diag::err_objc_synchronized_expects_object)
4290 << type << operand->getSourceRange();
4291 }
4292 }
4293 }
4294
4295 // The operand to @synchronized is a full-expression.
4296 return ActOnFinishFullExpr(operand, /*DiscardedValue*/ false);
4297 }
4298
4299 StmtResult
ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc,Expr * SyncExpr,Stmt * SyncBody)4300 Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr,
4301 Stmt *SyncBody) {
4302 // We can't jump into or indirect-jump out of a @synchronized block.
4303 setFunctionHasBranchProtectedScope();
4304 return new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody);
4305 }
4306
4307 /// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
4308 /// and creates a proper catch handler from them.
4309 StmtResult
ActOnCXXCatchBlock(SourceLocation CatchLoc,Decl * ExDecl,Stmt * HandlerBlock)4310 Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl,
4311 Stmt *HandlerBlock) {
4312 // There's nothing to test that ActOnExceptionDecl didn't already test.
4313 return new (Context)
4314 CXXCatchStmt(CatchLoc, cast_or_null<VarDecl>(ExDecl), HandlerBlock);
4315 }
4316
4317 StmtResult
ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc,Stmt * Body)4318 Sema::ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body) {
4319 setFunctionHasBranchProtectedScope();
4320 return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body);
4321 }
4322
4323 namespace {
4324 class CatchHandlerType {
4325 QualType QT;
4326 unsigned IsPointer : 1;
4327
4328 // This is a special constructor to be used only with DenseMapInfo's
4329 // getEmptyKey() and getTombstoneKey() functions.
4330 friend struct llvm::DenseMapInfo<CatchHandlerType>;
4331 enum Unique { ForDenseMap };
CatchHandlerType(QualType QT,Unique)4332 CatchHandlerType(QualType QT, Unique) : QT(QT), IsPointer(false) {}
4333
4334 public:
4335 /// Used when creating a CatchHandlerType from a handler type; will determine
4336 /// whether the type is a pointer or reference and will strip off the top
4337 /// level pointer and cv-qualifiers.
CatchHandlerType(QualType Q)4338 CatchHandlerType(QualType Q) : QT(Q), IsPointer(false) {
4339 if (QT->isPointerType())
4340 IsPointer = true;
4341
4342 if (IsPointer || QT->isReferenceType())
4343 QT = QT->getPointeeType();
4344 QT = QT.getUnqualifiedType();
4345 }
4346
4347 /// Used when creating a CatchHandlerType from a base class type; pretends the
4348 /// type passed in had the pointer qualifier, does not need to get an
4349 /// unqualified type.
CatchHandlerType(QualType QT,bool IsPointer)4350 CatchHandlerType(QualType QT, bool IsPointer)
4351 : QT(QT), IsPointer(IsPointer) {}
4352
underlying() const4353 QualType underlying() const { return QT; }
isPointer() const4354 bool isPointer() const { return IsPointer; }
4355
operator ==(const CatchHandlerType & LHS,const CatchHandlerType & RHS)4356 friend bool operator==(const CatchHandlerType &LHS,
4357 const CatchHandlerType &RHS) {
4358 // If the pointer qualification does not match, we can return early.
4359 if (LHS.IsPointer != RHS.IsPointer)
4360 return false;
4361 // Otherwise, check the underlying type without cv-qualifiers.
4362 return LHS.QT == RHS.QT;
4363 }
4364 };
4365 } // namespace
4366
4367 namespace llvm {
4368 template <> struct DenseMapInfo<CatchHandlerType> {
getEmptyKeyllvm::DenseMapInfo4369 static CatchHandlerType getEmptyKey() {
4370 return CatchHandlerType(DenseMapInfo<QualType>::getEmptyKey(),
4371 CatchHandlerType::ForDenseMap);
4372 }
4373
getTombstoneKeyllvm::DenseMapInfo4374 static CatchHandlerType getTombstoneKey() {
4375 return CatchHandlerType(DenseMapInfo<QualType>::getTombstoneKey(),
4376 CatchHandlerType::ForDenseMap);
4377 }
4378
getHashValuellvm::DenseMapInfo4379 static unsigned getHashValue(const CatchHandlerType &Base) {
4380 return DenseMapInfo<QualType>::getHashValue(Base.underlying());
4381 }
4382
isEqualllvm::DenseMapInfo4383 static bool isEqual(const CatchHandlerType &LHS,
4384 const CatchHandlerType &RHS) {
4385 return LHS == RHS;
4386 }
4387 };
4388 }
4389
4390 namespace {
4391 class CatchTypePublicBases {
4392 ASTContext &Ctx;
4393 const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &TypesToCheck;
4394 const bool CheckAgainstPointer;
4395
4396 CXXCatchStmt *FoundHandler;
4397 CanQualType FoundHandlerType;
4398
4399 public:
CatchTypePublicBases(ASTContext & Ctx,const llvm::DenseMap<CatchHandlerType,CXXCatchStmt * > & T,bool C)4400 CatchTypePublicBases(
4401 ASTContext &Ctx,
4402 const llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> &T, bool C)
4403 : Ctx(Ctx), TypesToCheck(T), CheckAgainstPointer(C),
4404 FoundHandler(nullptr) {}
4405
getFoundHandler() const4406 CXXCatchStmt *getFoundHandler() const { return FoundHandler; }
getFoundHandlerType() const4407 CanQualType getFoundHandlerType() const { return FoundHandlerType; }
4408
operator ()(const CXXBaseSpecifier * S,CXXBasePath &)4409 bool operator()(const CXXBaseSpecifier *S, CXXBasePath &) {
4410 if (S->getAccessSpecifier() == AccessSpecifier::AS_public) {
4411 CatchHandlerType Check(S->getType(), CheckAgainstPointer);
4412 const auto &M = TypesToCheck;
4413 auto I = M.find(Check);
4414 if (I != M.end()) {
4415 FoundHandler = I->second;
4416 FoundHandlerType = Ctx.getCanonicalType(S->getType());
4417 return true;
4418 }
4419 }
4420 return false;
4421 }
4422 };
4423 }
4424
4425 /// ActOnCXXTryBlock - Takes a try compound-statement and a number of
4426 /// handlers and creates a try statement from them.
ActOnCXXTryBlock(SourceLocation TryLoc,Stmt * TryBlock,ArrayRef<Stmt * > Handlers)4427 StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
4428 ArrayRef<Stmt *> Handlers) {
4429 // Don't report an error if 'try' is used in system headers.
4430 if (!getLangOpts().CXXExceptions &&
4431 !getSourceManager().isInSystemHeader(TryLoc) && !getLangOpts().CUDA) {
4432 // Delay error emission for the OpenMP device code.
4433 targetDiag(TryLoc, diag::err_exceptions_disabled) << "try";
4434 }
4435
4436 // Exceptions aren't allowed in CUDA device code.
4437 if (getLangOpts().CUDA)
4438 CUDADiagIfDeviceCode(TryLoc, diag::err_cuda_device_exceptions)
4439 << "try" << CurrentCUDATarget();
4440
4441 if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope())
4442 Diag(TryLoc, diag::err_omp_simd_region_cannot_use_stmt) << "try";
4443
4444 sema::FunctionScopeInfo *FSI = getCurFunction();
4445
4446 // C++ try is incompatible with SEH __try.
4447 if (!getLangOpts().Borland && FSI->FirstSEHTryLoc.isValid()) {
4448 Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
4449 Diag(FSI->FirstSEHTryLoc, diag::note_conflicting_try_here) << "'__try'";
4450 }
4451
4452 const unsigned NumHandlers = Handlers.size();
4453 assert(!Handlers.empty() &&
4454 "The parser shouldn't call this if there are no handlers.");
4455
4456 llvm::DenseMap<CatchHandlerType, CXXCatchStmt *> HandledTypes;
4457 for (unsigned i = 0; i < NumHandlers; ++i) {
4458 CXXCatchStmt *H = cast<CXXCatchStmt>(Handlers[i]);
4459
4460 // Diagnose when the handler is a catch-all handler, but it isn't the last
4461 // handler for the try block. [except.handle]p5. Also, skip exception
4462 // declarations that are invalid, since we can't usefully report on them.
4463 if (!H->getExceptionDecl()) {
4464 if (i < NumHandlers - 1)
4465 return StmtError(Diag(H->getBeginLoc(), diag::err_early_catch_all));
4466 continue;
4467 } else if (H->getExceptionDecl()->isInvalidDecl())
4468 continue;
4469
4470 // Walk the type hierarchy to diagnose when this type has already been
4471 // handled (duplication), or cannot be handled (derivation inversion). We
4472 // ignore top-level cv-qualifiers, per [except.handle]p3
4473 CatchHandlerType HandlerCHT =
4474 (QualType)Context.getCanonicalType(H->getCaughtType());
4475
4476 // We can ignore whether the type is a reference or a pointer; we need the
4477 // underlying declaration type in order to get at the underlying record
4478 // decl, if there is one.
4479 QualType Underlying = HandlerCHT.underlying();
4480 if (auto *RD = Underlying->getAsCXXRecordDecl()) {
4481 if (!RD->hasDefinition())
4482 continue;
4483 // Check that none of the public, unambiguous base classes are in the
4484 // map ([except.handle]p1). Give the base classes the same pointer
4485 // qualification as the original type we are basing off of. This allows
4486 // comparison against the handler type using the same top-level pointer
4487 // as the original type.
4488 CXXBasePaths Paths;
4489 Paths.setOrigin(RD);
4490 CatchTypePublicBases CTPB(Context, HandledTypes, HandlerCHT.isPointer());
4491 if (RD->lookupInBases(CTPB, Paths)) {
4492 const CXXCatchStmt *Problem = CTPB.getFoundHandler();
4493 if (!Paths.isAmbiguous(CTPB.getFoundHandlerType())) {
4494 Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
4495 diag::warn_exception_caught_by_earlier_handler)
4496 << H->getCaughtType();
4497 Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
4498 diag::note_previous_exception_handler)
4499 << Problem->getCaughtType();
4500 }
4501 }
4502 }
4503
4504 // Add the type the list of ones we have handled; diagnose if we've already
4505 // handled it.
4506 auto R = HandledTypes.insert(std::make_pair(H->getCaughtType(), H));
4507 if (!R.second) {
4508 const CXXCatchStmt *Problem = R.first->second;
4509 Diag(H->getExceptionDecl()->getTypeSpecStartLoc(),
4510 diag::warn_exception_caught_by_earlier_handler)
4511 << H->getCaughtType();
4512 Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(),
4513 diag::note_previous_exception_handler)
4514 << Problem->getCaughtType();
4515 }
4516 }
4517
4518 FSI->setHasCXXTry(TryLoc);
4519
4520 return CXXTryStmt::Create(Context, TryLoc, TryBlock, Handlers);
4521 }
4522
ActOnSEHTryBlock(bool IsCXXTry,SourceLocation TryLoc,Stmt * TryBlock,Stmt * Handler)4523 StmtResult Sema::ActOnSEHTryBlock(bool IsCXXTry, SourceLocation TryLoc,
4524 Stmt *TryBlock, Stmt *Handler) {
4525 assert(TryBlock && Handler);
4526
4527 sema::FunctionScopeInfo *FSI = getCurFunction();
4528
4529 // SEH __try is incompatible with C++ try. Borland appears to support this,
4530 // however.
4531 if (!getLangOpts().Borland) {
4532 if (FSI->FirstCXXTryLoc.isValid()) {
4533 Diag(TryLoc, diag::err_mixing_cxx_try_seh_try);
4534 Diag(FSI->FirstCXXTryLoc, diag::note_conflicting_try_here) << "'try'";
4535 }
4536 }
4537
4538 FSI->setHasSEHTry(TryLoc);
4539
4540 // Reject __try in Obj-C methods, blocks, and captured decls, since we don't
4541 // track if they use SEH.
4542 DeclContext *DC = CurContext;
4543 while (DC && !DC->isFunctionOrMethod())
4544 DC = DC->getParent();
4545 FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(DC);
4546 if (FD)
4547 FD->setUsesSEHTry(true);
4548 else
4549 Diag(TryLoc, diag::err_seh_try_outside_functions);
4550
4551 // Reject __try on unsupported targets.
4552 if (!Context.getTargetInfo().isSEHTrySupported())
4553 Diag(TryLoc, diag::err_seh_try_unsupported);
4554
4555 return SEHTryStmt::Create(Context, IsCXXTry, TryLoc, TryBlock, Handler);
4556 }
4557
ActOnSEHExceptBlock(SourceLocation Loc,Expr * FilterExpr,Stmt * Block)4558 StmtResult Sema::ActOnSEHExceptBlock(SourceLocation Loc, Expr *FilterExpr,
4559 Stmt *Block) {
4560 assert(FilterExpr && Block);
4561 QualType FTy = FilterExpr->getType();
4562 if (!FTy->isIntegerType() && !FTy->isDependentType()) {
4563 return StmtError(
4564 Diag(FilterExpr->getExprLoc(), diag::err_filter_expression_integral)
4565 << FTy);
4566 }
4567 return SEHExceptStmt::Create(Context, Loc, FilterExpr, Block);
4568 }
4569
ActOnStartSEHFinallyBlock()4570 void Sema::ActOnStartSEHFinallyBlock() {
4571 CurrentSEHFinally.push_back(CurScope);
4572 }
4573
ActOnAbortSEHFinallyBlock()4574 void Sema::ActOnAbortSEHFinallyBlock() {
4575 CurrentSEHFinally.pop_back();
4576 }
4577
ActOnFinishSEHFinallyBlock(SourceLocation Loc,Stmt * Block)4578 StmtResult Sema::ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block) {
4579 assert(Block);
4580 CurrentSEHFinally.pop_back();
4581 return SEHFinallyStmt::Create(Context, Loc, Block);
4582 }
4583
4584 StmtResult
ActOnSEHLeaveStmt(SourceLocation Loc,Scope * CurScope)4585 Sema::ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope) {
4586 Scope *SEHTryParent = CurScope;
4587 while (SEHTryParent && !SEHTryParent->isSEHTryScope())
4588 SEHTryParent = SEHTryParent->getParent();
4589 if (!SEHTryParent)
4590 return StmtError(Diag(Loc, diag::err_ms___leave_not_in___try));
4591 CheckJumpOutOfSEHFinally(*this, Loc, *SEHTryParent);
4592
4593 return new (Context) SEHLeaveStmt(Loc);
4594 }
4595
BuildMSDependentExistsStmt(SourceLocation KeywordLoc,bool IsIfExists,NestedNameSpecifierLoc QualifierLoc,DeclarationNameInfo NameInfo,Stmt * Nested)4596 StmtResult Sema::BuildMSDependentExistsStmt(SourceLocation KeywordLoc,
4597 bool IsIfExists,
4598 NestedNameSpecifierLoc QualifierLoc,
4599 DeclarationNameInfo NameInfo,
4600 Stmt *Nested)
4601 {
4602 return new (Context) MSDependentExistsStmt(KeywordLoc, IsIfExists,
4603 QualifierLoc, NameInfo,
4604 cast<CompoundStmt>(Nested));
4605 }
4606
4607
ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,bool IsIfExists,CXXScopeSpec & SS,UnqualifiedId & Name,Stmt * Nested)4608 StmtResult Sema::ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,
4609 bool IsIfExists,
4610 CXXScopeSpec &SS,
4611 UnqualifiedId &Name,
4612 Stmt *Nested) {
4613 return BuildMSDependentExistsStmt(KeywordLoc, IsIfExists,
4614 SS.getWithLocInContext(Context),
4615 GetNameFromUnqualifiedId(Name),
4616 Nested);
4617 }
4618
4619 RecordDecl*
CreateCapturedStmtRecordDecl(CapturedDecl * & CD,SourceLocation Loc,unsigned NumParams)4620 Sema::CreateCapturedStmtRecordDecl(CapturedDecl *&CD, SourceLocation Loc,
4621 unsigned NumParams) {
4622 DeclContext *DC = CurContext;
4623 while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
4624 DC = DC->getParent();
4625
4626 RecordDecl *RD = nullptr;
4627 if (getLangOpts().CPlusPlus)
4628 RD = CXXRecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc,
4629 /*Id=*/nullptr);
4630 else
4631 RD = RecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc, /*Id=*/nullptr);
4632
4633 RD->setCapturedRecord();
4634 DC->addDecl(RD);
4635 RD->setImplicit();
4636 RD->startDefinition();
4637
4638 assert(NumParams > 0 && "CapturedStmt requires context parameter");
4639 CD = CapturedDecl::Create(Context, CurContext, NumParams);
4640 DC->addDecl(CD);
4641 return RD;
4642 }
4643
4644 static bool
buildCapturedStmtCaptureList(Sema & S,CapturedRegionScopeInfo * RSI,SmallVectorImpl<CapturedStmt::Capture> & Captures,SmallVectorImpl<Expr * > & CaptureInits)4645 buildCapturedStmtCaptureList(Sema &S, CapturedRegionScopeInfo *RSI,
4646 SmallVectorImpl<CapturedStmt::Capture> &Captures,
4647 SmallVectorImpl<Expr *> &CaptureInits) {
4648 for (const sema::Capture &Cap : RSI->Captures) {
4649 if (Cap.isInvalid())
4650 continue;
4651
4652 // Form the initializer for the capture.
4653 ExprResult Init = S.BuildCaptureInit(Cap, Cap.getLocation(),
4654 RSI->CapRegionKind == CR_OpenMP);
4655
4656 // FIXME: Bail out now if the capture is not used and the initializer has
4657 // no side-effects.
4658
4659 // Create a field for this capture.
4660 FieldDecl *Field = S.BuildCaptureField(RSI->TheRecordDecl, Cap);
4661
4662 // Add the capture to our list of captures.
4663 if (Cap.isThisCapture()) {
4664 Captures.push_back(CapturedStmt::Capture(Cap.getLocation(),
4665 CapturedStmt::VCK_This));
4666 } else if (Cap.isVLATypeCapture()) {
4667 Captures.push_back(
4668 CapturedStmt::Capture(Cap.getLocation(), CapturedStmt::VCK_VLAType));
4669 } else {
4670 assert(Cap.isVariableCapture() && "unknown kind of capture");
4671
4672 if (S.getLangOpts().OpenMP && RSI->CapRegionKind == CR_OpenMP)
4673 S.setOpenMPCaptureKind(Field, Cap.getVariable(), RSI->OpenMPLevel);
4674
4675 Captures.push_back(CapturedStmt::Capture(Cap.getLocation(),
4676 Cap.isReferenceCapture()
4677 ? CapturedStmt::VCK_ByRef
4678 : CapturedStmt::VCK_ByCopy,
4679 Cap.getVariable()));
4680 }
4681 CaptureInits.push_back(Init.get());
4682 }
4683 return false;
4684 }
4685
ActOnCapturedRegionStart(SourceLocation Loc,Scope * CurScope,CapturedRegionKind Kind,unsigned NumParams)4686 void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
4687 CapturedRegionKind Kind,
4688 unsigned NumParams) {
4689 CapturedDecl *CD = nullptr;
4690 RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, NumParams);
4691
4692 // Build the context parameter
4693 DeclContext *DC = CapturedDecl::castToDeclContext(CD);
4694 IdentifierInfo *ParamName = &Context.Idents.get("__context");
4695 QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
4696 auto *Param =
4697 ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType,
4698 ImplicitParamDecl::CapturedContext);
4699 DC->addDecl(Param);
4700
4701 CD->setContextParam(0, Param);
4702
4703 // Enter the capturing scope for this captured region.
4704 PushCapturedRegionScope(CurScope, CD, RD, Kind);
4705
4706 if (CurScope)
4707 PushDeclContext(CurScope, CD);
4708 else
4709 CurContext = CD;
4710
4711 PushExpressionEvaluationContext(
4712 ExpressionEvaluationContext::PotentiallyEvaluated);
4713 }
4714
ActOnCapturedRegionStart(SourceLocation Loc,Scope * CurScope,CapturedRegionKind Kind,ArrayRef<CapturedParamNameType> Params,unsigned OpenMPCaptureLevel)4715 void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
4716 CapturedRegionKind Kind,
4717 ArrayRef<CapturedParamNameType> Params,
4718 unsigned OpenMPCaptureLevel) {
4719 CapturedDecl *CD = nullptr;
4720 RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, Params.size());
4721
4722 // Build the context parameter
4723 DeclContext *DC = CapturedDecl::castToDeclContext(CD);
4724 bool ContextIsFound = false;
4725 unsigned ParamNum = 0;
4726 for (ArrayRef<CapturedParamNameType>::iterator I = Params.begin(),
4727 E = Params.end();
4728 I != E; ++I, ++ParamNum) {
4729 if (I->second.isNull()) {
4730 assert(!ContextIsFound &&
4731 "null type has been found already for '__context' parameter");
4732 IdentifierInfo *ParamName = &Context.Idents.get("__context");
4733 QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD))
4734 .withConst()
4735 .withRestrict();
4736 auto *Param =
4737 ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType,
4738 ImplicitParamDecl::CapturedContext);
4739 DC->addDecl(Param);
4740 CD->setContextParam(ParamNum, Param);
4741 ContextIsFound = true;
4742 } else {
4743 IdentifierInfo *ParamName = &Context.Idents.get(I->first);
4744 auto *Param =
4745 ImplicitParamDecl::Create(Context, DC, Loc, ParamName, I->second,
4746 ImplicitParamDecl::CapturedContext);
4747 DC->addDecl(Param);
4748 CD->setParam(ParamNum, Param);
4749 }
4750 }
4751 assert(ContextIsFound && "no null type for '__context' parameter");
4752 if (!ContextIsFound) {
4753 // Add __context implicitly if it is not specified.
4754 IdentifierInfo *ParamName = &Context.Idents.get("__context");
4755 QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD));
4756 auto *Param =
4757 ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType,
4758 ImplicitParamDecl::CapturedContext);
4759 DC->addDecl(Param);
4760 CD->setContextParam(ParamNum, Param);
4761 }
4762 // Enter the capturing scope for this captured region.
4763 PushCapturedRegionScope(CurScope, CD, RD, Kind, OpenMPCaptureLevel);
4764
4765 if (CurScope)
4766 PushDeclContext(CurScope, CD);
4767 else
4768 CurContext = CD;
4769
4770 PushExpressionEvaluationContext(
4771 ExpressionEvaluationContext::PotentiallyEvaluated);
4772 }
4773
ActOnCapturedRegionError()4774 void Sema::ActOnCapturedRegionError() {
4775 DiscardCleanupsInEvaluationContext();
4776 PopExpressionEvaluationContext();
4777 PopDeclContext();
4778 PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo();
4779 CapturedRegionScopeInfo *RSI = cast<CapturedRegionScopeInfo>(ScopeRAII.get());
4780
4781 RecordDecl *Record = RSI->TheRecordDecl;
4782 Record->setInvalidDecl();
4783
4784 SmallVector<Decl*, 4> Fields(Record->fields());
4785 ActOnFields(/*Scope=*/nullptr, Record->getLocation(), Record, Fields,
4786 SourceLocation(), SourceLocation(), ParsedAttributesView());
4787 }
4788
ActOnCapturedRegionEnd(Stmt * S)4789 StmtResult Sema::ActOnCapturedRegionEnd(Stmt *S) {
4790 // Leave the captured scope before we start creating captures in the
4791 // enclosing scope.
4792 DiscardCleanupsInEvaluationContext();
4793 PopExpressionEvaluationContext();
4794 PopDeclContext();
4795 PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo();
4796 CapturedRegionScopeInfo *RSI = cast<CapturedRegionScopeInfo>(ScopeRAII.get());
4797
4798 SmallVector<CapturedStmt::Capture, 4> Captures;
4799 SmallVector<Expr *, 4> CaptureInits;
4800 if (buildCapturedStmtCaptureList(*this, RSI, Captures, CaptureInits))
4801 return StmtError();
4802
4803 CapturedDecl *CD = RSI->TheCapturedDecl;
4804 RecordDecl *RD = RSI->TheRecordDecl;
4805
4806 CapturedStmt *Res = CapturedStmt::Create(
4807 getASTContext(), S, static_cast<CapturedRegionKind>(RSI->CapRegionKind),
4808 Captures, CaptureInits, CD, RD);
4809
4810 CD->setBody(Res->getCapturedStmt());
4811 RD->completeDefinition();
4812
4813 return Res;
4814 }
4815