1 //===--- SemaLambda.cpp - Semantic Analysis for C++11 Lambdas -------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements semantic analysis for C++ lambda expressions.
12 //===----------------------------------------------------------------------===//
13 #include "clang/Sema/DeclSpec.h"
14 #include "TypeLocBuilder.h"
15 #include "clang/AST/ASTLambda.h"
16 #include "clang/AST/ExprCXX.h"
17 #include "clang/Basic/TargetInfo.h"
18 #include "clang/Sema/Initialization.h"
19 #include "clang/Sema/Lookup.h"
20 #include "clang/Sema/Scope.h"
21 #include "clang/Sema/ScopeInfo.h"
22 #include "clang/Sema/SemaInternal.h"
23 #include "clang/Sema/SemaLambda.h"
24 using namespace clang;
27 /// \brief Examines the FunctionScopeInfo stack to determine the nearest
28 /// enclosing lambda (to the current lambda) that is 'capture-ready' for
29 /// the variable referenced in the current lambda (i.e. \p VarToCapture).
30 /// If successful, returns the index into Sema's FunctionScopeInfo stack
31 /// of the capture-ready lambda's LambdaScopeInfo.
33 /// Climbs down the stack of lambdas (deepest nested lambda - i.e. current
34 /// lambda - is on top) to determine the index of the nearest enclosing/outer
35 /// lambda that is ready to capture the \p VarToCapture being referenced in
36 /// the current lambda.
37 /// As we climb down the stack, we want the index of the first such lambda -
38 /// that is the lambda with the highest index that is 'capture-ready'.
40 /// A lambda 'L' is capture-ready for 'V' (var or this) if:
41 /// - its enclosing context is non-dependent
42 /// - and if the chain of lambdas between L and the lambda in which
43 /// V is potentially used (i.e. the lambda at the top of the scope info
44 /// stack), can all capture or have already captured V.
45 /// If \p VarToCapture is 'null' then we are trying to capture 'this'.
47 /// Note that a lambda that is deemed 'capture-ready' still needs to be checked
48 /// for whether it is 'capture-capable' (see
49 /// getStackIndexOfNearestEnclosingCaptureCapableLambda), before it can truly
52 /// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
53 /// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
54 /// is at the top of the stack and has the highest index.
55 /// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
57 /// \returns An Optional<unsigned> Index that if evaluates to 'true' contains
58 /// the index (into Sema's FunctionScopeInfo stack) of the innermost lambda
59 /// which is capture-ready. If the return value evaluates to 'false' then
60 /// no lambda is capture-ready for \p VarToCapture.
62 static inline Optional<unsigned>
63 getStackIndexOfNearestEnclosingCaptureReadyLambda(
64 ArrayRef<const clang::sema::FunctionScopeInfo *> FunctionScopes,
65 VarDecl *VarToCapture) {
66 // Label failure to capture.
67 const Optional<unsigned> NoLambdaIsCaptureReady;
69 // Ignore all inner captured regions.
70 unsigned CurScopeIndex = FunctionScopes.size() - 1;
71 while (CurScopeIndex > 0 && isa<clang::sema::CapturedRegionScopeInfo>(
72 FunctionScopes[CurScopeIndex]))
75 isa<clang::sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]) &&
76 "The function on the top of sema's function-info stack must be a lambda");
78 // If VarToCapture is null, we are attempting to capture 'this'.
79 const bool IsCapturingThis = !VarToCapture;
80 const bool IsCapturingVariable = !IsCapturingThis;
82 // Start with the current lambda at the top of the stack (highest index).
83 DeclContext *EnclosingDC =
84 cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex])->CallOperator;
87 const clang::sema::LambdaScopeInfo *LSI =
88 cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]);
89 // IF we have climbed down to an intervening enclosing lambda that contains
90 // the variable declaration - it obviously can/must not capture the
92 // Since its enclosing DC is dependent, all the lambdas between it and the
93 // innermost nested lambda are dependent (otherwise we wouldn't have
94 // arrived here) - so we don't yet have a lambda that can capture the
96 if (IsCapturingVariable &&
97 VarToCapture->getDeclContext()->Equals(EnclosingDC))
98 return NoLambdaIsCaptureReady;
100 // For an enclosing lambda to be capture ready for an entity, all
101 // intervening lambda's have to be able to capture that entity. If even
102 // one of the intervening lambda's is not capable of capturing the entity
103 // then no enclosing lambda can ever capture that entity.
107 // [](auto b) { #2 <-- an intervening lambda that can never capture 'x'
109 // f(x, c); <-- can not lead to x's speculative capture by #1 or #2
111 // If they do not have a default implicit capture, check to see
112 // if the entity has already been explicitly captured.
113 // If even a single dependent enclosing lambda lacks the capability
114 // to ever capture this variable, there is no further enclosing
115 // non-dependent lambda that can capture this variable.
116 if (LSI->ImpCaptureStyle == sema::LambdaScopeInfo::ImpCap_None) {
117 if (IsCapturingVariable && !LSI->isCaptured(VarToCapture))
118 return NoLambdaIsCaptureReady;
119 if (IsCapturingThis && !LSI->isCXXThisCaptured())
120 return NoLambdaIsCaptureReady;
122 EnclosingDC = getLambdaAwareParentOfDeclContext(EnclosingDC);
124 assert(CurScopeIndex);
126 } while (!EnclosingDC->isTranslationUnit() &&
127 EnclosingDC->isDependentContext() &&
128 isLambdaCallOperator(EnclosingDC));
130 assert(CurScopeIndex < (FunctionScopes.size() - 1));
131 // If the enclosingDC is not dependent, then the immediately nested lambda
132 // (one index above) is capture-ready.
133 if (!EnclosingDC->isDependentContext())
134 return CurScopeIndex + 1;
135 return NoLambdaIsCaptureReady;
138 /// \brief Examines the FunctionScopeInfo stack to determine the nearest
139 /// enclosing lambda (to the current lambda) that is 'capture-capable' for
140 /// the variable referenced in the current lambda (i.e. \p VarToCapture).
141 /// If successful, returns the index into Sema's FunctionScopeInfo stack
142 /// of the capture-capable lambda's LambdaScopeInfo.
144 /// Given the current stack of lambdas being processed by Sema and
145 /// the variable of interest, to identify the nearest enclosing lambda (to the
146 /// current lambda at the top of the stack) that can truly capture
147 /// a variable, it has to have the following two properties:
148 /// a) 'capture-ready' - be the innermost lambda that is 'capture-ready':
149 /// - climb down the stack (i.e. starting from the innermost and examining
150 /// each outer lambda step by step) checking if each enclosing
151 /// lambda can either implicitly or explicitly capture the variable.
152 /// Record the first such lambda that is enclosed in a non-dependent
153 /// context. If no such lambda currently exists return failure.
154 /// b) 'capture-capable' - make sure the 'capture-ready' lambda can truly
155 /// capture the variable by checking all its enclosing lambdas:
156 /// - check if all outer lambdas enclosing the 'capture-ready' lambda
157 /// identified above in 'a' can also capture the variable (this is done
158 /// via tryCaptureVariable for variables and CheckCXXThisCapture for
159 /// 'this' by passing in the index of the Lambda identified in step 'a')
161 /// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
162 /// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
163 /// is at the top of the stack.
165 /// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
168 /// \returns An Optional<unsigned> Index that if evaluates to 'true' contains
169 /// the index (into Sema's FunctionScopeInfo stack) of the innermost lambda
170 /// which is capture-capable. If the return value evaluates to 'false' then
171 /// no lambda is capture-capable for \p VarToCapture.
173 Optional<unsigned> clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
174 ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
175 VarDecl *VarToCapture, Sema &S) {
177 const Optional<unsigned> NoLambdaIsCaptureCapable;
179 const Optional<unsigned> OptionalStackIndex =
180 getStackIndexOfNearestEnclosingCaptureReadyLambda(FunctionScopes,
182 if (!OptionalStackIndex)
183 return NoLambdaIsCaptureCapable;
185 const unsigned IndexOfCaptureReadyLambda = OptionalStackIndex.getValue();
186 assert(((IndexOfCaptureReadyLambda != (FunctionScopes.size() - 1)) ||
187 S.getCurGenericLambda()) &&
188 "The capture ready lambda for a potential capture can only be the "
189 "current lambda if it is a generic lambda");
191 const sema::LambdaScopeInfo *const CaptureReadyLambdaLSI =
192 cast<sema::LambdaScopeInfo>(FunctionScopes[IndexOfCaptureReadyLambda]);
194 // If VarToCapture is null, we are attempting to capture 'this'
195 const bool IsCapturingThis = !VarToCapture;
196 const bool IsCapturingVariable = !IsCapturingThis;
198 if (IsCapturingVariable) {
199 // Check if the capture-ready lambda can truly capture the variable, by
200 // checking whether all enclosing lambdas of the capture-ready lambda allow
201 // the capture - i.e. make sure it is capture-capable.
202 QualType CaptureType, DeclRefType;
203 const bool CanCaptureVariable =
204 !S.tryCaptureVariable(VarToCapture,
205 /*ExprVarIsUsedInLoc*/ SourceLocation(),
206 clang::Sema::TryCapture_Implicit,
207 /*EllipsisLoc*/ SourceLocation(),
208 /*BuildAndDiagnose*/ false, CaptureType,
209 DeclRefType, &IndexOfCaptureReadyLambda);
210 if (!CanCaptureVariable)
211 return NoLambdaIsCaptureCapable;
213 // Check if the capture-ready lambda can truly capture 'this' by checking
214 // whether all enclosing lambdas of the capture-ready lambda can capture
216 const bool CanCaptureThis =
217 !S.CheckCXXThisCapture(
218 CaptureReadyLambdaLSI->PotentialThisCaptureLocation,
219 /*Explicit*/ false, /*BuildAndDiagnose*/ false,
220 &IndexOfCaptureReadyLambda);
222 return NoLambdaIsCaptureCapable;
224 return IndexOfCaptureReadyLambda;
227 static inline TemplateParameterList *
228 getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) {
229 if (LSI->GLTemplateParameterList)
230 return LSI->GLTemplateParameterList;
232 if (!LSI->AutoTemplateParams.empty()) {
233 SourceRange IntroRange = LSI->IntroducerRange;
234 SourceLocation LAngleLoc = IntroRange.getBegin();
235 SourceLocation RAngleLoc = IntroRange.getEnd();
236 LSI->GLTemplateParameterList = TemplateParameterList::Create(
238 /*Template kw loc*/ SourceLocation(), LAngleLoc,
239 llvm::makeArrayRef((NamedDecl *const *)LSI->AutoTemplateParams.data(),
240 LSI->AutoTemplateParams.size()),
243 return LSI->GLTemplateParameterList;
246 CXXRecordDecl *Sema::createLambdaClosureType(SourceRange IntroducerRange,
247 TypeSourceInfo *Info,
249 LambdaCaptureDefault CaptureDefault) {
250 DeclContext *DC = CurContext;
251 while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
252 DC = DC->getParent();
253 bool IsGenericLambda = getGenericLambdaTemplateParameterList(getCurLambda(),
255 // Start constructing the lambda class.
256 CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(Context, DC, Info,
257 IntroducerRange.getBegin(),
266 /// \brief Determine whether the given context is or is enclosed in an inline
268 static bool isInInlineFunction(const DeclContext *DC) {
269 while (!DC->isFileContext()) {
270 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
274 DC = DC->getLexicalParent();
280 MangleNumberingContext *
281 Sema::getCurrentMangleNumberContext(const DeclContext *DC,
282 Decl *&ManglingContextDecl) {
283 // Compute the context for allocating mangling numbers in the current
284 // expression, if the ABI requires them.
285 ManglingContextDecl = ExprEvalContexts.back().ManglingContextDecl;
296 // Default arguments of member function parameters that appear in a class
297 // definition, as well as the initializers of data members, receive special
298 // treatment. Identify them.
299 if (ManglingContextDecl) {
300 if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(ManglingContextDecl)) {
301 if (const DeclContext *LexicalDC
302 = Param->getDeclContext()->getLexicalParent())
303 if (LexicalDC->isRecord())
304 Kind = DefaultArgument;
305 } else if (VarDecl *Var = dyn_cast<VarDecl>(ManglingContextDecl)) {
306 if (Var->getDeclContext()->isRecord())
307 Kind = StaticDataMember;
308 else if (Var->getMostRecentDecl()->isInline())
309 Kind = InlineVariable;
310 else if (Var->getDescribedVarTemplate())
311 Kind = VariableTemplate;
312 else if (auto *VTS = dyn_cast<VarTemplateSpecializationDecl>(Var)) {
313 if (!VTS->isExplicitSpecialization())
314 Kind = VariableTemplate;
316 } else if (isa<FieldDecl>(ManglingContextDecl)) {
321 // Itanium ABI [5.1.7]:
322 // In the following contexts [...] the one-definition rule requires closure
323 // types in different translation units to "correspond":
324 bool IsInNonspecializedTemplate =
325 inTemplateInstantiation() || CurContext->isDependentContext();
328 // -- the bodies of non-exported nonspecialized template functions
329 // -- the bodies of inline functions
330 if ((IsInNonspecializedTemplate &&
331 !(ManglingContextDecl && isa<ParmVarDecl>(ManglingContextDecl))) ||
332 isInInlineFunction(CurContext)) {
333 ManglingContextDecl = nullptr;
334 while (auto *CD = dyn_cast<CapturedDecl>(DC))
335 DC = CD->getParent();
336 return &Context.getManglingNumberContext(DC);
339 ManglingContextDecl = nullptr;
343 case StaticDataMember:
344 // -- the initializers of nonspecialized static members of template classes
345 if (!IsInNonspecializedTemplate) {
346 ManglingContextDecl = nullptr;
349 // Fall through to get the current context.
353 // -- the in-class initializers of class members
354 case DefaultArgument:
355 // -- default arguments appearing in class definitions
357 // -- the initializers of inline variables
358 case VariableTemplate:
359 // -- the initializers of templated variables
360 return &ExprEvalContexts.back().getMangleNumberingContext(Context);
363 llvm_unreachable("unexpected context");
366 MangleNumberingContext &
367 Sema::ExpressionEvaluationContextRecord::getMangleNumberingContext(
369 assert(ManglingContextDecl && "Need to have a context declaration");
370 if (!MangleNumbering)
371 MangleNumbering = Ctx.createMangleNumberingContext();
372 return *MangleNumbering;
375 CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
376 SourceRange IntroducerRange,
377 TypeSourceInfo *MethodTypeInfo,
378 SourceLocation EndLoc,
379 ArrayRef<ParmVarDecl *> Params,
380 const bool IsConstexprSpecified) {
381 QualType MethodType = MethodTypeInfo->getType();
382 TemplateParameterList *TemplateParams =
383 getGenericLambdaTemplateParameterList(getCurLambda(), *this);
384 // If a lambda appears in a dependent context or is a generic lambda (has
385 // template parameters) and has an 'auto' return type, deduce it to a
387 if (Class->isDependentContext() || TemplateParams) {
388 const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
389 QualType Result = FPT->getReturnType();
390 if (Result->isUndeducedType()) {
391 Result = SubstAutoType(Result, Context.DependentTy);
392 MethodType = Context.getFunctionType(Result, FPT->getParamTypes(),
393 FPT->getExtProtoInfo());
397 // C++11 [expr.prim.lambda]p5:
398 // The closure type for a lambda-expression has a public inline function
399 // call operator (13.5.4) whose parameters and return type are described by
400 // the lambda-expression's parameter-declaration-clause and
401 // trailing-return-type respectively.
402 DeclarationName MethodName
403 = Context.DeclarationNames.getCXXOperatorName(OO_Call);
404 DeclarationNameLoc MethodNameLoc;
405 MethodNameLoc.CXXOperatorName.BeginOpNameLoc
406 = IntroducerRange.getBegin().getRawEncoding();
407 MethodNameLoc.CXXOperatorName.EndOpNameLoc
408 = IntroducerRange.getEnd().getRawEncoding();
409 CXXMethodDecl *Method
410 = CXXMethodDecl::Create(Context, Class, EndLoc,
411 DeclarationNameInfo(MethodName,
412 IntroducerRange.getBegin(),
414 MethodType, MethodTypeInfo,
417 IsConstexprSpecified,
419 Method->setAccess(AS_public);
421 // Temporarily set the lexical declaration context to the current
422 // context, so that the Scope stack matches the lexical nesting.
423 Method->setLexicalDeclContext(CurContext);
424 // Create a function template if we have a template parameter list
425 FunctionTemplateDecl *const TemplateMethod = TemplateParams ?
426 FunctionTemplateDecl::Create(Context, Class,
427 Method->getLocation(), MethodName,
430 if (TemplateMethod) {
431 TemplateMethod->setLexicalDeclContext(CurContext);
432 TemplateMethod->setAccess(AS_public);
433 Method->setDescribedFunctionTemplate(TemplateMethod);
437 if (!Params.empty()) {
438 Method->setParams(Params);
439 CheckParmsForFunctionDef(Params,
440 /*CheckParameterNames=*/false);
442 for (auto P : Method->parameters())
443 P->setOwningFunction(Method);
446 Decl *ManglingContextDecl;
447 if (MangleNumberingContext *MCtx =
448 getCurrentMangleNumberContext(Class->getDeclContext(),
449 ManglingContextDecl)) {
450 unsigned ManglingNumber = MCtx->getManglingNumber(Method);
451 Class->setLambdaMangling(ManglingNumber, ManglingContextDecl);
457 void Sema::buildLambdaScope(LambdaScopeInfo *LSI,
458 CXXMethodDecl *CallOperator,
459 SourceRange IntroducerRange,
460 LambdaCaptureDefault CaptureDefault,
461 SourceLocation CaptureDefaultLoc,
463 bool ExplicitResultType,
465 LSI->CallOperator = CallOperator;
466 CXXRecordDecl *LambdaClass = CallOperator->getParent();
467 LSI->Lambda = LambdaClass;
468 if (CaptureDefault == LCD_ByCopy)
469 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
470 else if (CaptureDefault == LCD_ByRef)
471 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
472 LSI->CaptureDefaultLoc = CaptureDefaultLoc;
473 LSI->IntroducerRange = IntroducerRange;
474 LSI->ExplicitParams = ExplicitParams;
475 LSI->Mutable = Mutable;
477 if (ExplicitResultType) {
478 LSI->ReturnType = CallOperator->getReturnType();
480 if (!LSI->ReturnType->isDependentType() &&
481 !LSI->ReturnType->isVoidType()) {
482 if (RequireCompleteType(CallOperator->getLocStart(), LSI->ReturnType,
483 diag::err_lambda_incomplete_result)) {
488 LSI->HasImplicitReturnType = true;
492 void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
493 LSI->finishedExplicitCaptures();
496 void Sema::addLambdaParameters(CXXMethodDecl *CallOperator, Scope *CurScope) {
497 // Introduce our parameters into the function scope
498 for (unsigned p = 0, NumParams = CallOperator->getNumParams();
499 p < NumParams; ++p) {
500 ParmVarDecl *Param = CallOperator->getParamDecl(p);
502 // If this has an identifier, add it to the scope stack.
503 if (CurScope && Param->getIdentifier()) {
504 CheckShadow(CurScope, Param);
506 PushOnScopeChains(Param, CurScope);
511 /// If this expression is an enumerator-like expression of some type
512 /// T, return the type T; otherwise, return null.
514 /// Pointer comparisons on the result here should always work because
515 /// it's derived from either the parent of an EnumConstantDecl
516 /// (i.e. the definition) or the declaration returned by
517 /// EnumType::getDecl() (i.e. the definition).
518 static EnumDecl *findEnumForBlockReturn(Expr *E) {
519 // An expression is an enumerator-like expression of type T if,
520 // ignoring parens and parens-like expressions:
521 E = E->IgnoreParens();
523 // - it is an enumerator whose enum type is T or
524 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
525 if (EnumConstantDecl *D
526 = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
527 return cast<EnumDecl>(D->getDeclContext());
532 // - it is a comma expression whose RHS is an enumerator-like
533 // expression of type T or
534 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
535 if (BO->getOpcode() == BO_Comma)
536 return findEnumForBlockReturn(BO->getRHS());
540 // - it is a statement-expression whose value expression is an
541 // enumerator-like expression of type T or
542 if (StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
543 if (Expr *last = dyn_cast_or_null<Expr>(SE->getSubStmt()->body_back()))
544 return findEnumForBlockReturn(last);
548 // - it is a ternary conditional operator (not the GNU ?:
549 // extension) whose second and third operands are
550 // enumerator-like expressions of type T or
551 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
552 if (EnumDecl *ED = findEnumForBlockReturn(CO->getTrueExpr()))
553 if (ED == findEnumForBlockReturn(CO->getFalseExpr()))
559 // - it is an implicit integral conversion applied to an
560 // enumerator-like expression of type T or
561 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
562 // We can sometimes see integral conversions in valid
563 // enumerator-like expressions.
564 if (ICE->getCastKind() == CK_IntegralCast)
565 return findEnumForBlockReturn(ICE->getSubExpr());
567 // Otherwise, just rely on the type.
570 // - it is an expression of that formal enum type.
571 if (const EnumType *ET = E->getType()->getAs<EnumType>()) {
572 return ET->getDecl();
579 /// Attempt to find a type T for which the returned expression of the
580 /// given statement is an enumerator-like expression of that type.
581 static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
582 if (Expr *retValue = ret->getRetValue())
583 return findEnumForBlockReturn(retValue);
587 /// Attempt to find a common type T for which all of the returned
588 /// expressions in a block are enumerator-like expressions of that
590 static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
591 ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
593 // Try to find one for the first return.
594 EnumDecl *ED = findEnumForBlockReturn(*i);
595 if (!ED) return nullptr;
597 // Check that the rest of the returns have the same enum.
598 for (++i; i != e; ++i) {
599 if (findEnumForBlockReturn(*i) != ED)
603 // Never infer an anonymous enum type.
604 if (!ED->hasNameForLinkage()) return nullptr;
609 /// Adjust the given return statements so that they formally return
610 /// the given type. It should require, at most, an IntegralCast.
611 static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
612 QualType returnType) {
613 for (ArrayRef<ReturnStmt*>::iterator
614 i = returns.begin(), e = returns.end(); i != e; ++i) {
615 ReturnStmt *ret = *i;
616 Expr *retValue = ret->getRetValue();
617 if (S.Context.hasSameType(retValue->getType(), returnType))
620 // Right now we only support integral fixup casts.
621 assert(returnType->isIntegralOrUnscopedEnumerationType());
622 assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
624 ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(retValue);
626 Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
627 E = ImplicitCastExpr::Create(S.Context, returnType, CK_IntegralCast,
628 E, /*base path*/ nullptr, VK_RValue);
630 cleanups->setSubExpr(E);
637 void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
638 assert(CSI.HasImplicitReturnType);
639 // If it was ever a placeholder, it had to been deduced to DependentTy.
640 assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
641 assert((!isa<LambdaScopeInfo>(CSI) || !getLangOpts().CPlusPlus14) &&
642 "lambda expressions use auto deduction in C++14 onwards");
644 // C++ core issue 975:
645 // If a lambda-expression does not include a trailing-return-type,
646 // it is as if the trailing-return-type denotes the following type:
647 // - if there are no return statements in the compound-statement,
648 // or all return statements return either an expression of type
649 // void or no expression or braced-init-list, the type void;
650 // - otherwise, if all return statements return an expression
651 // and the types of the returned expressions after
652 // lvalue-to-rvalue conversion (4.1 [conv.lval]),
653 // array-to-pointer conversion (4.2 [conv.array]), and
654 // function-to-pointer conversion (4.3 [conv.func]) are the
655 // same, that common type;
656 // - otherwise, the program is ill-formed.
658 // C++ core issue 1048 additionally removes top-level cv-qualifiers
659 // from the types of returned expressions to match the C++14 auto
662 // In addition, in blocks in non-C++ modes, if all of the return
663 // statements are enumerator-like expressions of some type T, where
664 // T has a name for linkage, then we infer the return type of the
665 // block to be that type.
667 // First case: no return statements, implicit void return type.
668 ASTContext &Ctx = getASTContext();
669 if (CSI.Returns.empty()) {
670 // It's possible there were simply no /valid/ return statements.
671 // In this case, the first one we found may have at least given us a type.
672 if (CSI.ReturnType.isNull())
673 CSI.ReturnType = Ctx.VoidTy;
677 // Second case: at least one return statement has dependent type.
678 // Delay type checking until instantiation.
679 assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
680 if (CSI.ReturnType->isDependentType())
683 // Try to apply the enum-fuzz rule.
684 if (!getLangOpts().CPlusPlus) {
685 assert(isa<BlockScopeInfo>(CSI));
686 const EnumDecl *ED = findCommonEnumForBlockReturns(CSI.Returns);
688 CSI.ReturnType = Context.getTypeDeclType(ED);
689 adjustBlockReturnsToEnum(*this, CSI.Returns, CSI.ReturnType);
694 // Third case: only one return statement. Don't bother doing extra work!
695 SmallVectorImpl<ReturnStmt*>::iterator I = CSI.Returns.begin(),
696 E = CSI.Returns.end();
700 // General case: many return statements.
701 // Check that they all have compatible return types.
703 // We require the return types to strictly match here.
704 // Note that we've already done the required promotions as part of
705 // processing the return statement.
706 for (; I != E; ++I) {
707 const ReturnStmt *RS = *I;
708 const Expr *RetE = RS->getRetValue();
710 QualType ReturnType =
711 (RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
712 if (Context.getCanonicalFunctionResultType(ReturnType) ==
713 Context.getCanonicalFunctionResultType(CSI.ReturnType))
716 // FIXME: This is a poor diagnostic for ReturnStmts without expressions.
717 // TODO: It's possible that the *first* return is the divergent one.
718 Diag(RS->getLocStart(),
719 diag::err_typecheck_missing_return_type_incompatible)
720 << ReturnType << CSI.ReturnType
721 << isa<LambdaScopeInfo>(CSI);
722 // Continue iterating so that we keep emitting diagnostics.
726 QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
731 // Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
733 QualType DeductType = Context.getAutoDeductType();
735 TLB.pushTypeSpec(DeductType).setNameLoc(Loc);
737 DeductType = BuildReferenceType(DeductType, true, Loc, Id);
738 assert(!DeductType.isNull() && "can't build reference to auto");
739 TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
741 TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
743 // Deduce the type of the init capture.
744 QualType DeducedType = deduceVarTypeFromInitializer(
745 /*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
746 SourceRange(Loc, Loc), IsDirectInit, Init);
747 if (DeducedType.isNull())
750 // Are we a non-list direct initialization?
751 ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
753 // Perform initialization analysis and ensure any implicit conversions
754 // (such as lvalue-to-rvalue) are enforced.
755 InitializedEntity Entity =
756 InitializedEntity::InitializeLambdaCapture(Id, DeducedType, Loc);
757 InitializationKind Kind =
759 ? (CXXDirectInit ? InitializationKind::CreateDirect(
760 Loc, Init->getLocStart(), Init->getLocEnd())
761 : InitializationKind::CreateDirectList(Loc))
762 : InitializationKind::CreateCopy(Loc, Init->getLocStart());
764 MultiExprArg Args = Init;
767 MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
769 InitializationSequence InitSeq(*this, Entity, Kind, Args);
770 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
772 if (Result.isInvalid())
774 Init = Result.getAs<Expr>();
776 // The init-capture initialization is a full-expression that must be
777 // processed as one before we enter the declcontext of the lambda's
779 Result = ActOnFinishFullExpr(Init, Loc, /*DiscardedValue*/ false,
780 /*IsConstexpr*/ false,
781 /*IsLambdaInitCaptureInitializer*/ true);
782 if (Result.isInvalid())
785 Init = Result.getAs<Expr>();
789 VarDecl *Sema::createLambdaInitCaptureVarDecl(SourceLocation Loc,
790 QualType InitCaptureType,
792 unsigned InitStyle, Expr *Init) {
793 TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType,
795 // Create a dummy variable representing the init-capture. This is not actually
796 // used as a variable, and only exists as a way to name and refer to the
798 // FIXME: Pass in separate source locations for '&' and identifier.
799 VarDecl *NewVD = VarDecl::Create(Context, CurContext, Loc,
800 Loc, Id, InitCaptureType, TSI, SC_Auto);
801 NewVD->setInitCapture(true);
802 NewVD->setReferenced(true);
803 // FIXME: Pass in a VarDecl::InitializationStyle.
804 NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
805 NewVD->markUsed(Context);
806 NewVD->setInit(Init);
810 FieldDecl *Sema::buildInitCaptureField(LambdaScopeInfo *LSI, VarDecl *Var) {
811 FieldDecl *Field = FieldDecl::Create(
812 Context, LSI->Lambda, Var->getLocation(), Var->getLocation(),
813 nullptr, Var->getType(), Var->getTypeSourceInfo(), nullptr, false,
815 Field->setImplicit(true);
816 Field->setAccess(AS_private);
817 LSI->Lambda->addDecl(Field);
819 LSI->addCapture(Var, /*isBlock*/false, Var->getType()->isReferenceType(),
820 /*isNested*/false, Var->getLocation(), SourceLocation(),
821 Var->getType(), Var->getInit());
825 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
826 Declarator &ParamInfo,
828 // Determine if we're within a context where we know that the lambda will
829 // be dependent, because there are template parameters in scope.
830 bool KnownDependent = false;
831 LambdaScopeInfo *const LSI = getCurLambda();
832 assert(LSI && "LambdaScopeInfo should be on stack!");
834 // The lambda-expression's closure type might be dependent even if its
835 // semantic context isn't, if it appears within a default argument of a
836 // function template.
837 if (CurScope->getTemplateParamParent())
838 KnownDependent = true;
840 // Determine the signature of the call operator.
841 TypeSourceInfo *MethodTyInfo;
842 bool ExplicitParams = true;
843 bool ExplicitResultType = true;
844 bool ContainsUnexpandedParameterPack = false;
845 SourceLocation EndLoc;
846 SmallVector<ParmVarDecl *, 8> Params;
847 if (ParamInfo.getNumTypeObjects() == 0) {
848 // C++11 [expr.prim.lambda]p4:
849 // If a lambda-expression does not include a lambda-declarator, it is as
850 // if the lambda-declarator were ().
851 FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(
852 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
853 EPI.HasTrailingReturn = true;
854 EPI.TypeQuals |= DeclSpec::TQ_const;
855 // C++1y [expr.prim.lambda]:
856 // The lambda return type is 'auto', which is replaced by the
857 // trailing-return type if provided and/or deduced from 'return'
859 // We don't do this before C++1y, because we don't support deduced return
861 QualType DefaultTypeForNoTrailingReturn =
862 getLangOpts().CPlusPlus14 ? Context.getAutoDeductType()
863 : Context.DependentTy;
865 Context.getFunctionType(DefaultTypeForNoTrailingReturn, None, EPI);
866 MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy);
867 ExplicitParams = false;
868 ExplicitResultType = false;
869 EndLoc = Intro.Range.getEnd();
871 assert(ParamInfo.isFunctionDeclarator() &&
872 "lambda-declarator is a function");
873 DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
875 // C++11 [expr.prim.lambda]p5:
876 // This function call operator is declared const (9.3.1) if and only if
877 // the lambda-expression's parameter-declaration-clause is not followed
878 // by mutable. It is neither virtual nor declared volatile. [...]
879 if (!FTI.hasMutableQualifier())
880 FTI.TypeQuals |= DeclSpec::TQ_const;
882 MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope);
883 assert(MethodTyInfo && "no type from lambda-declarator");
884 EndLoc = ParamInfo.getSourceRange().getEnd();
886 ExplicitResultType = FTI.hasTrailingReturnType();
888 if (FTIHasNonVoidParameters(FTI)) {
889 Params.reserve(FTI.NumParams);
890 for (unsigned i = 0, e = FTI.NumParams; i != e; ++i)
891 Params.push_back(cast<ParmVarDecl>(FTI.Params[i].Param));
894 // Check for unexpanded parameter packs in the method type.
895 if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
896 ContainsUnexpandedParameterPack = true;
899 CXXRecordDecl *Class = createLambdaClosureType(Intro.Range, MethodTyInfo,
900 KnownDependent, Intro.Default);
902 CXXMethodDecl *Method =
903 startLambdaDefinition(Class, Intro.Range, MethodTyInfo, EndLoc, Params,
904 ParamInfo.getDeclSpec().isConstexprSpecified());
906 CheckCXXDefaultArguments(Method);
908 // Attributes on the lambda apply to the method.
909 ProcessDeclAttributes(CurScope, Method, ParamInfo);
911 // CUDA lambdas get implicit attributes based on the scope in which they're
913 if (getLangOpts().CUDA)
914 CUDASetLambdaAttrs(Method);
916 // Introduce the function call operator as the current declaration context.
917 PushDeclContext(CurScope, Method);
919 // Build the lambda scope.
920 buildLambdaScope(LSI, Method, Intro.Range, Intro.Default, Intro.DefaultLoc,
921 ExplicitParams, ExplicitResultType, !Method->isConst());
923 // C++11 [expr.prim.lambda]p9:
924 // A lambda-expression whose smallest enclosing scope is a block scope is a
925 // local lambda expression; any other lambda expression shall not have a
926 // capture-default or simple-capture in its lambda-introducer.
928 // For simple-captures, this is covered by the check below that any named
929 // entity is a variable that can be captured.
931 // For DR1632, we also allow a capture-default in any context where we can
932 // odr-use 'this' (in particular, in a default initializer for a non-static
934 if (Intro.Default != LCD_None && !Class->getParent()->isFunctionOrMethod() &&
935 (getCurrentThisType().isNull() ||
936 CheckCXXThisCapture(SourceLocation(), /*Explicit*/true,
937 /*BuildAndDiagnose*/false)))
938 Diag(Intro.DefaultLoc, diag::err_capture_default_non_local);
940 // Distinct capture names, for diagnostics.
941 llvm::SmallSet<IdentifierInfo*, 8> CaptureNames;
943 // Handle explicit captures.
944 SourceLocation PrevCaptureLoc
945 = Intro.Default == LCD_None? Intro.Range.getBegin() : Intro.DefaultLoc;
946 for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
947 PrevCaptureLoc = C->Loc, ++C) {
948 if (C->Kind == LCK_This || C->Kind == LCK_StarThis) {
949 if (C->Kind == LCK_StarThis)
950 Diag(C->Loc, !getLangOpts().CPlusPlus17
951 ? diag::ext_star_this_lambda_capture_cxx17
952 : diag::warn_cxx14_compat_star_this_lambda_capture);
954 // C++11 [expr.prim.lambda]p8:
955 // An identifier or this shall not appear more than once in a
957 if (LSI->isCXXThisCaptured()) {
958 Diag(C->Loc, diag::err_capture_more_than_once)
959 << "'this'" << SourceRange(LSI->getCXXThisCapture().getLocation())
960 << FixItHint::CreateRemoval(
961 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
965 // C++2a [expr.prim.lambda]p8:
966 // If a lambda-capture includes a capture-default that is =,
967 // each simple-capture of that lambda-capture shall be of the form
968 // "&identifier", "this", or "* this". [ Note: The form [&,this] is
969 // redundant but accepted for compatibility with ISO C++14. --end note ]
970 if (Intro.Default == LCD_ByCopy && C->Kind != LCK_StarThis)
971 Diag(C->Loc, !getLangOpts().CPlusPlus2a
972 ? diag::ext_equals_this_lambda_capture_cxx2a
973 : diag::warn_cxx17_compat_equals_this_lambda_capture);
975 // C++11 [expr.prim.lambda]p12:
976 // If this is captured by a local lambda expression, its nearest
977 // enclosing function shall be a non-static member function.
978 QualType ThisCaptureType = getCurrentThisType();
979 if (ThisCaptureType.isNull()) {
980 Diag(C->Loc, diag::err_this_capture) << true;
984 CheckCXXThisCapture(C->Loc, /*Explicit=*/true, /*BuildAndDiagnose*/ true,
985 /*FunctionScopeIndexToStopAtPtr*/ nullptr,
986 C->Kind == LCK_StarThis);
990 assert(C->Id && "missing identifier for capture");
992 if (C->Init.isInvalid())
995 VarDecl *Var = nullptr;
996 if (C->Init.isUsable()) {
997 Diag(C->Loc, getLangOpts().CPlusPlus14
998 ? diag::warn_cxx11_compat_init_capture
999 : diag::ext_init_capture);
1001 if (C->Init.get()->containsUnexpandedParameterPack())
1002 ContainsUnexpandedParameterPack = true;
1003 // If the initializer expression is usable, but the InitCaptureType
1004 // is not, then an error has occurred - so ignore the capture for now.
1005 // for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
1006 // FIXME: we should create the init capture variable and mark it invalid
1008 if (C->InitCaptureType.get().isNull())
1012 switch (C->InitKind) {
1013 case LambdaCaptureInitKind::NoInit:
1014 llvm_unreachable("not an init-capture?");
1015 case LambdaCaptureInitKind::CopyInit:
1016 InitStyle = VarDecl::CInit;
1018 case LambdaCaptureInitKind::DirectInit:
1019 InitStyle = VarDecl::CallInit;
1021 case LambdaCaptureInitKind::ListInit:
1022 InitStyle = VarDecl::ListInit;
1025 Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
1026 C->Id, InitStyle, C->Init.get());
1027 // C++1y [expr.prim.lambda]p11:
1028 // An init-capture behaves as if it declares and explicitly
1029 // captures a variable [...] whose declarative region is the
1030 // lambda-expression's compound-statement
1032 PushOnScopeChains(Var, CurScope, false);
1034 assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
1035 "init capture has valid but null init?");
1037 // C++11 [expr.prim.lambda]p8:
1038 // If a lambda-capture includes a capture-default that is &, the
1039 // identifiers in the lambda-capture shall not be preceded by &.
1040 // If a lambda-capture includes a capture-default that is =, [...]
1041 // each identifier it contains shall be preceded by &.
1042 if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
1043 Diag(C->Loc, diag::err_reference_capture_with_reference_default)
1044 << FixItHint::CreateRemoval(
1045 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1047 } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
1048 Diag(C->Loc, diag::err_copy_capture_with_copy_default)
1049 << FixItHint::CreateRemoval(
1050 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1054 // C++11 [expr.prim.lambda]p10:
1055 // The identifiers in a capture-list are looked up using the usual
1056 // rules for unqualified name lookup (3.4.1)
1057 DeclarationNameInfo Name(C->Id, C->Loc);
1058 LookupResult R(*this, Name, LookupOrdinaryName);
1059 LookupName(R, CurScope);
1060 if (R.isAmbiguous())
1063 // FIXME: Disable corrections that would add qualification?
1064 CXXScopeSpec ScopeSpec;
1065 if (DiagnoseEmptyLookup(CurScope, ScopeSpec, R,
1066 llvm::make_unique<DeclFilterCCC<VarDecl>>()))
1070 Var = R.getAsSingle<VarDecl>();
1071 if (Var && DiagnoseUseOfDecl(Var, C->Loc))
1075 // C++11 [expr.prim.lambda]p8:
1076 // An identifier or this shall not appear more than once in a
1078 if (!CaptureNames.insert(C->Id).second) {
1079 if (Var && LSI->isCaptured(Var)) {
1080 Diag(C->Loc, diag::err_capture_more_than_once)
1081 << C->Id << SourceRange(LSI->getCapture(Var).getLocation())
1082 << FixItHint::CreateRemoval(
1083 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1085 // Previous capture captured something different (one or both was
1086 // an init-cpature): no fixit.
1087 Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
1091 // C++11 [expr.prim.lambda]p10:
1092 // [...] each such lookup shall find a variable with automatic storage
1093 // duration declared in the reaching scope of the local lambda expression.
1094 // Note that the 'reaching scope' check happens in tryCaptureVariable().
1096 Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id;
1100 // Ignore invalid decls; they'll just confuse the code later.
1101 if (Var->isInvalidDecl())
1104 if (!Var->hasLocalStorage()) {
1105 Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id;
1106 Diag(Var->getLocation(), diag::note_previous_decl) << C->Id;
1110 // C++11 [expr.prim.lambda]p23:
1111 // A capture followed by an ellipsis is a pack expansion (14.5.3).
1112 SourceLocation EllipsisLoc;
1113 if (C->EllipsisLoc.isValid()) {
1114 if (Var->isParameterPack()) {
1115 EllipsisLoc = C->EllipsisLoc;
1117 Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
1118 << SourceRange(C->Loc);
1120 // Just ignore the ellipsis.
1122 } else if (Var->isParameterPack()) {
1123 ContainsUnexpandedParameterPack = true;
1126 if (C->Init.isUsable()) {
1127 buildInitCaptureField(LSI, Var);
1129 TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef :
1130 TryCapture_ExplicitByVal;
1131 tryCaptureVariable(Var, C->Loc, Kind, EllipsisLoc);
1134 finishLambdaExplicitCaptures(LSI);
1136 LSI->ContainsUnexpandedParameterPack = ContainsUnexpandedParameterPack;
1138 // Add lambda parameters into scope.
1139 addLambdaParameters(Method, CurScope);
1141 // Enter a new evaluation context to insulate the lambda from any
1142 // cleanups from the enclosing full-expression.
1143 PushExpressionEvaluationContext(
1144 ExpressionEvaluationContext::PotentiallyEvaluated);
1147 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
1148 bool IsInstantiation) {
1149 LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
1151 // Leave the expression-evaluation context.
1152 DiscardCleanupsInEvaluationContext();
1153 PopExpressionEvaluationContext();
1155 // Leave the context of the lambda.
1156 if (!IsInstantiation)
1159 // Finalize the lambda.
1160 CXXRecordDecl *Class = LSI->Lambda;
1161 Class->setInvalidDecl();
1162 SmallVector<Decl*, 4> Fields(Class->fields());
1163 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1164 SourceLocation(), nullptr);
1165 CheckCompletedCXXClass(Class);
1167 PopFunctionScopeInfo();
1170 QualType Sema::getLambdaConversionFunctionResultType(
1171 const FunctionProtoType *CallOpProto) {
1172 // The function type inside the pointer type is the same as the call
1173 // operator with some tweaks. The calling convention is the default free
1174 // function convention, and the type qualifications are lost.
1175 const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
1176 CallOpProto->getExtProtoInfo();
1177 FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
1178 CallingConv CC = Context.getDefaultCallingConvention(
1179 CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
1180 InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(CC);
1181 InvokerExtInfo.TypeQuals = 0;
1182 assert(InvokerExtInfo.RefQualifier == RQ_None &&
1183 "Lambda's call operator should not have a reference qualifier");
1184 return Context.getFunctionType(CallOpProto->getReturnType(),
1185 CallOpProto->getParamTypes(), InvokerExtInfo);
1188 /// \brief Add a lambda's conversion to function pointer, as described in
1189 /// C++11 [expr.prim.lambda]p6.
1190 static void addFunctionPointerConversion(Sema &S,
1191 SourceRange IntroducerRange,
1192 CXXRecordDecl *Class,
1193 CXXMethodDecl *CallOperator) {
1194 // This conversion is explicitly disabled if the lambda's function has
1195 // pass_object_size attributes on any of its parameters.
1196 auto HasPassObjectSizeAttr = [](const ParmVarDecl *P) {
1197 return P->hasAttr<PassObjectSizeAttr>();
1199 if (llvm::any_of(CallOperator->parameters(), HasPassObjectSizeAttr))
1202 // Add the conversion to function pointer.
1203 QualType InvokerFunctionTy = S.getLambdaConversionFunctionResultType(
1204 CallOperator->getType()->castAs<FunctionProtoType>());
1205 QualType PtrToFunctionTy = S.Context.getPointerType(InvokerFunctionTy);
1207 // Create the type of the conversion function.
1208 FunctionProtoType::ExtProtoInfo ConvExtInfo(
1209 S.Context.getDefaultCallingConvention(
1210 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1211 // The conversion function is always const.
1212 ConvExtInfo.TypeQuals = Qualifiers::Const;
1214 S.Context.getFunctionType(PtrToFunctionTy, None, ConvExtInfo);
1216 SourceLocation Loc = IntroducerRange.getBegin();
1217 DeclarationName ConversionName
1218 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1219 S.Context.getCanonicalType(PtrToFunctionTy));
1220 DeclarationNameLoc ConvNameLoc;
1221 // Construct a TypeSourceInfo for the conversion function, and wire
1222 // all the parameters appropriately for the FunctionProtoTypeLoc
1223 // so that everything works during transformation/instantiation of
1225 // The main reason for wiring up the parameters of the conversion
1226 // function with that of the call operator is so that constructs
1227 // like the following work:
1228 // auto L = [](auto b) { <-- 1
1229 // return [](auto a) -> decltype(a) { <-- 2
1233 // int (*fp)(int) = L(5);
1234 // Because the trailing return type can contain DeclRefExprs that refer
1235 // to the original call operator's variables, we hijack the call
1236 // operators ParmVarDecls below.
1237 TypeSourceInfo *ConvNamePtrToFunctionTSI =
1238 S.Context.getTrivialTypeSourceInfo(PtrToFunctionTy, Loc);
1239 ConvNameLoc.NamedType.TInfo = ConvNamePtrToFunctionTSI;
1241 // The conversion function is a conversion to a pointer-to-function.
1242 TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(ConvTy, Loc);
1243 FunctionProtoTypeLoc ConvTL =
1244 ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
1245 // Get the result of the conversion function which is a pointer-to-function.
1246 PointerTypeLoc PtrToFunctionTL =
1247 ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
1248 // Do the same for the TypeSourceInfo that is used to name the conversion
1250 PointerTypeLoc ConvNamePtrToFunctionTL =
1251 ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
1253 // Get the underlying function types that the conversion function will
1254 // be converting to (should match the type of the call operator).
1255 FunctionProtoTypeLoc CallOpConvTL =
1256 PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1257 FunctionProtoTypeLoc CallOpConvNameTL =
1258 ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1260 // Wire up the FunctionProtoTypeLocs with the call operator's parameters.
1261 // These parameter's are essentially used to transform the name and
1262 // the type of the conversion operator. By using the same parameters
1263 // as the call operator's we don't have to fix any back references that
1264 // the trailing return type of the call operator's uses (such as
1265 // decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
1266 // - we can simply use the return type of the call operator, and
1267 // everything should work.
1268 SmallVector<ParmVarDecl *, 4> InvokerParams;
1269 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1270 ParmVarDecl *From = CallOperator->getParamDecl(I);
1272 InvokerParams.push_back(ParmVarDecl::Create(S.Context,
1273 // Temporarily add to the TU. This is set to the invoker below.
1274 S.Context.getTranslationUnitDecl(),
1275 From->getLocStart(),
1276 From->getLocation(),
1277 From->getIdentifier(),
1279 From->getTypeSourceInfo(),
1280 From->getStorageClass(),
1281 /*DefaultArg=*/nullptr));
1282 CallOpConvTL.setParam(I, From);
1283 CallOpConvNameTL.setParam(I, From);
1286 CXXConversionDecl *Conversion
1287 = CXXConversionDecl::Create(S.Context, Class, Loc,
1288 DeclarationNameInfo(ConversionName,
1292 /*isInline=*/true, /*isExplicit=*/false,
1293 /*isConstexpr=*/S.getLangOpts().CPlusPlus17,
1294 CallOperator->getBody()->getLocEnd());
1295 Conversion->setAccess(AS_public);
1296 Conversion->setImplicit(true);
1298 if (Class->isGenericLambda()) {
1299 // Create a template version of the conversion operator, using the template
1300 // parameter list of the function call operator.
1301 FunctionTemplateDecl *TemplateCallOperator =
1302 CallOperator->getDescribedFunctionTemplate();
1303 FunctionTemplateDecl *ConversionTemplate =
1304 FunctionTemplateDecl::Create(S.Context, Class,
1305 Loc, ConversionName,
1306 TemplateCallOperator->getTemplateParameters(),
1308 ConversionTemplate->setAccess(AS_public);
1309 ConversionTemplate->setImplicit(true);
1310 Conversion->setDescribedFunctionTemplate(ConversionTemplate);
1311 Class->addDecl(ConversionTemplate);
1313 Class->addDecl(Conversion);
1314 // Add a non-static member function that will be the result of
1315 // the conversion with a certain unique ID.
1316 DeclarationName InvokerName = &S.Context.Idents.get(
1317 getLambdaStaticInvokerName());
1318 // FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
1319 // we should get a prebuilt TrivialTypeSourceInfo from Context
1320 // using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
1321 // then rewire the parameters accordingly, by hoisting up the InvokeParams
1322 // loop below and then use its Params to set Invoke->setParams(...) below.
1323 // This would avoid the 'const' qualifier of the calloperator from
1324 // contaminating the type of the invoker, which is currently adjusted
1325 // in SemaTemplateDeduction.cpp:DeduceTemplateArguments. Fixing the
1326 // trailing return type of the invoker would require a visitor to rebuild
1327 // the trailing return type and adjusting all back DeclRefExpr's to refer
1328 // to the new static invoker parameters - not the call operator's.
1329 CXXMethodDecl *Invoke
1330 = CXXMethodDecl::Create(S.Context, Class, Loc,
1331 DeclarationNameInfo(InvokerName, Loc),
1333 CallOperator->getTypeSourceInfo(),
1334 SC_Static, /*IsInline=*/true,
1335 /*IsConstexpr=*/false,
1336 CallOperator->getBody()->getLocEnd());
1337 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
1338 InvokerParams[I]->setOwningFunction(Invoke);
1339 Invoke->setParams(InvokerParams);
1340 Invoke->setAccess(AS_private);
1341 Invoke->setImplicit(true);
1342 if (Class->isGenericLambda()) {
1343 FunctionTemplateDecl *TemplateCallOperator =
1344 CallOperator->getDescribedFunctionTemplate();
1345 FunctionTemplateDecl *StaticInvokerTemplate = FunctionTemplateDecl::Create(
1346 S.Context, Class, Loc, InvokerName,
1347 TemplateCallOperator->getTemplateParameters(),
1349 StaticInvokerTemplate->setAccess(AS_private);
1350 StaticInvokerTemplate->setImplicit(true);
1351 Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
1352 Class->addDecl(StaticInvokerTemplate);
1354 Class->addDecl(Invoke);
1357 /// \brief Add a lambda's conversion to block pointer.
1358 static void addBlockPointerConversion(Sema &S,
1359 SourceRange IntroducerRange,
1360 CXXRecordDecl *Class,
1361 CXXMethodDecl *CallOperator) {
1362 QualType FunctionTy = S.getLambdaConversionFunctionResultType(
1363 CallOperator->getType()->castAs<FunctionProtoType>());
1364 QualType BlockPtrTy = S.Context.getBlockPointerType(FunctionTy);
1366 FunctionProtoType::ExtProtoInfo ConversionEPI(
1367 S.Context.getDefaultCallingConvention(
1368 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1369 ConversionEPI.TypeQuals = Qualifiers::Const;
1370 QualType ConvTy = S.Context.getFunctionType(BlockPtrTy, None, ConversionEPI);
1372 SourceLocation Loc = IntroducerRange.getBegin();
1373 DeclarationName Name
1374 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1375 S.Context.getCanonicalType(BlockPtrTy));
1376 DeclarationNameLoc NameLoc;
1377 NameLoc.NamedType.TInfo = S.Context.getTrivialTypeSourceInfo(BlockPtrTy, Loc);
1378 CXXConversionDecl *Conversion
1379 = CXXConversionDecl::Create(S.Context, Class, Loc,
1380 DeclarationNameInfo(Name, Loc, NameLoc),
1382 S.Context.getTrivialTypeSourceInfo(ConvTy, Loc),
1383 /*isInline=*/true, /*isExplicit=*/false,
1384 /*isConstexpr=*/false,
1385 CallOperator->getBody()->getLocEnd());
1386 Conversion->setAccess(AS_public);
1387 Conversion->setImplicit(true);
1388 Class->addDecl(Conversion);
1391 static ExprResult performLambdaVarCaptureInitialization(
1392 Sema &S, const LambdaScopeInfo::Capture &Capture, FieldDecl *Field) {
1393 assert(Capture.isVariableCapture() && "not a variable capture");
1395 auto *Var = Capture.getVariable();
1396 SourceLocation Loc = Capture.getLocation();
1398 // C++11 [expr.prim.lambda]p21:
1399 // When the lambda-expression is evaluated, the entities that
1400 // are captured by copy are used to direct-initialize each
1401 // corresponding non-static data member of the resulting closure
1402 // object. (For array members, the array elements are
1403 // direct-initialized in increasing subscript order.) These
1404 // initializations are performed in the (unspecified) order in
1405 // which the non-static data members are declared.
1407 // C++ [expr.prim.lambda]p12:
1408 // An entity captured by a lambda-expression is odr-used (3.2) in
1409 // the scope containing the lambda-expression.
1410 ExprResult RefResult = S.BuildDeclarationNameExpr(
1411 CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
1412 if (RefResult.isInvalid())
1414 Expr *Ref = RefResult.get();
1416 auto Entity = InitializedEntity::InitializeLambdaCapture(
1417 Var->getIdentifier(), Field->getType(), Loc);
1418 InitializationKind InitKind = InitializationKind::CreateDirect(Loc, Loc, Loc);
1419 InitializationSequence Init(S, Entity, InitKind, Ref);
1420 return Init.Perform(S, Entity, InitKind, Ref);
1423 ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
1425 LambdaScopeInfo LSI = *cast<LambdaScopeInfo>(FunctionScopes.back());
1426 ActOnFinishFunctionBody(LSI.CallOperator, Body);
1427 return BuildLambdaExpr(StartLoc, Body->getLocEnd(), &LSI);
1430 static LambdaCaptureDefault
1431 mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
1433 case CapturingScopeInfo::ImpCap_None:
1435 case CapturingScopeInfo::ImpCap_LambdaByval:
1437 case CapturingScopeInfo::ImpCap_CapturedRegion:
1438 case CapturingScopeInfo::ImpCap_LambdaByref:
1440 case CapturingScopeInfo::ImpCap_Block:
1441 llvm_unreachable("block capture in lambda");
1443 llvm_unreachable("Unknown implicit capture style");
1446 bool Sema::CaptureHasSideEffects(const LambdaScopeInfo::Capture &From) {
1447 if (!From.isVLATypeCapture()) {
1448 Expr *Init = From.getInitExpr();
1449 if (Init && Init->HasSideEffects(Context))
1453 if (!From.isCopyCapture())
1456 const QualType T = From.isThisCapture()
1457 ? getCurrentThisType()->getPointeeType()
1458 : From.getCaptureType();
1460 if (T.isVolatileQualified())
1463 const Type *BaseT = T->getBaseElementTypeUnsafe();
1464 if (const CXXRecordDecl *RD = BaseT->getAsCXXRecordDecl())
1465 return !RD->isCompleteDefinition() || !RD->hasTrivialCopyConstructor() ||
1466 !RD->hasTrivialDestructor();
1471 void Sema::DiagnoseUnusedLambdaCapture(const LambdaScopeInfo::Capture &From) {
1472 if (CaptureHasSideEffects(From))
1475 if (From.isVLATypeCapture())
1478 auto diag = Diag(From.getLocation(), diag::warn_unused_lambda_capture);
1479 if (From.isThisCapture())
1482 diag << From.getVariable();
1483 diag << From.isNonODRUsed();
1486 ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
1487 LambdaScopeInfo *LSI) {
1488 // Collect information from the lambda scope.
1489 SmallVector<LambdaCapture, 4> Captures;
1490 SmallVector<Expr *, 4> CaptureInits;
1491 SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
1492 LambdaCaptureDefault CaptureDefault =
1493 mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
1494 CXXRecordDecl *Class;
1495 CXXMethodDecl *CallOperator;
1496 SourceRange IntroducerRange;
1497 bool ExplicitParams;
1498 bool ExplicitResultType;
1499 CleanupInfo LambdaCleanup;
1500 bool ContainsUnexpandedParameterPack;
1501 bool IsGenericLambda;
1503 CallOperator = LSI->CallOperator;
1504 Class = LSI->Lambda;
1505 IntroducerRange = LSI->IntroducerRange;
1506 ExplicitParams = LSI->ExplicitParams;
1507 ExplicitResultType = !LSI->HasImplicitReturnType;
1508 LambdaCleanup = LSI->Cleanup;
1509 ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
1510 IsGenericLambda = Class->isGenericLambda();
1512 CallOperator->setLexicalDeclContext(Class);
1513 Decl *TemplateOrNonTemplateCallOperatorDecl =
1514 CallOperator->getDescribedFunctionTemplate()
1515 ? CallOperator->getDescribedFunctionTemplate()
1516 : cast<Decl>(CallOperator);
1518 TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
1519 Class->addDecl(TemplateOrNonTemplateCallOperatorDecl);
1521 PopExpressionEvaluationContext();
1523 // Translate captures.
1524 auto CurField = Class->field_begin();
1525 for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I, ++CurField) {
1526 const LambdaScopeInfo::Capture &From = LSI->Captures[I];
1527 assert(!From.isBlockCapture() && "Cannot capture __block variables");
1528 bool IsImplicit = I >= LSI->NumExplicitCaptures;
1530 // Warn about unused explicit captures.
1531 if (!CurContext->isDependentContext() && !IsImplicit && !From.isODRUsed()) {
1532 // Initialized captures that are non-ODR used may not be eliminated.
1533 bool NonODRUsedInitCapture =
1534 IsGenericLambda && From.isNonODRUsed() && From.getInitExpr();
1535 if (!NonODRUsedInitCapture)
1536 DiagnoseUnusedLambdaCapture(From);
1539 // Handle 'this' capture.
1540 if (From.isThisCapture()) {
1542 LambdaCapture(From.getLocation(), IsImplicit,
1543 From.isCopyCapture() ? LCK_StarThis : LCK_This));
1544 CaptureInits.push_back(From.getInitExpr());
1547 if (From.isVLATypeCapture()) {
1549 LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType));
1550 CaptureInits.push_back(nullptr);
1554 VarDecl *Var = From.getVariable();
1555 LambdaCaptureKind Kind = From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
1556 Captures.push_back(LambdaCapture(From.getLocation(), IsImplicit, Kind,
1557 Var, From.getEllipsisLoc()));
1558 Expr *Init = From.getInitExpr();
1561 performLambdaVarCaptureInitialization(*this, From, *CurField);
1562 if (InitResult.isInvalid())
1564 Init = InitResult.get();
1566 CaptureInits.push_back(Init);
1569 // C++11 [expr.prim.lambda]p6:
1570 // The closure type for a lambda-expression with no lambda-capture
1571 // has a public non-virtual non-explicit const conversion function
1572 // to pointer to function having the same parameter and return
1573 // types as the closure type's function call operator.
1574 if (Captures.empty() && CaptureDefault == LCD_None)
1575 addFunctionPointerConversion(*this, IntroducerRange, Class,
1579 // The closure type for a lambda-expression has a public non-virtual
1580 // non-explicit const conversion function to a block pointer having the
1581 // same parameter and return types as the closure type's function call
1583 // FIXME: Fix generic lambda to block conversions.
1584 if (getLangOpts().Blocks && getLangOpts().ObjC1 && !IsGenericLambda)
1585 addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
1587 // Finalize the lambda class.
1588 SmallVector<Decl*, 4> Fields(Class->fields());
1589 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1590 SourceLocation(), nullptr);
1591 CheckCompletedCXXClass(Class);
1594 Cleanup.mergeFrom(LambdaCleanup);
1596 LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange,
1597 CaptureDefault, CaptureDefaultLoc,
1599 ExplicitParams, ExplicitResultType,
1600 CaptureInits, EndLoc,
1601 ContainsUnexpandedParameterPack);
1602 // If the lambda expression's call operator is not explicitly marked constexpr
1603 // and we are not in a dependent context, analyze the call operator to infer
1604 // its constexpr-ness, suppressing diagnostics while doing so.
1605 if (getLangOpts().CPlusPlus17 && !CallOperator->isInvalidDecl() &&
1606 !CallOperator->isConstexpr() &&
1607 !isa<CoroutineBodyStmt>(CallOperator->getBody()) &&
1608 !Class->getDeclContext()->isDependentContext()) {
1609 TentativeAnalysisScope DiagnosticScopeGuard(*this);
1610 CallOperator->setConstexpr(
1611 CheckConstexprFunctionDecl(CallOperator) &&
1612 CheckConstexprFunctionBody(CallOperator, CallOperator->getBody()));
1615 // Emit delayed shadowing warnings now that the full capture list is known.
1616 DiagnoseShadowingLambdaDecls(LSI);
1618 if (!CurContext->isDependentContext()) {
1619 switch (ExprEvalContexts.back().Context) {
1620 // C++11 [expr.prim.lambda]p2:
1621 // A lambda-expression shall not appear in an unevaluated operand
1623 case ExpressionEvaluationContext::Unevaluated:
1624 case ExpressionEvaluationContext::UnevaluatedList:
1625 case ExpressionEvaluationContext::UnevaluatedAbstract:
1626 // C++1y [expr.const]p2:
1627 // A conditional-expression e is a core constant expression unless the
1628 // evaluation of e, following the rules of the abstract machine, would
1629 // evaluate [...] a lambda-expression.
1631 // This is technically incorrect, there are some constant evaluated contexts
1632 // where this should be allowed. We should probably fix this when DR1607 is
1633 // ratified, it lays out the exact set of conditions where we shouldn't
1634 // allow a lambda-expression.
1635 case ExpressionEvaluationContext::ConstantEvaluated:
1636 // We don't actually diagnose this case immediately, because we
1637 // could be within a context where we might find out later that
1638 // the expression is potentially evaluated (e.g., for typeid).
1639 ExprEvalContexts.back().Lambdas.push_back(Lambda);
1642 case ExpressionEvaluationContext::DiscardedStatement:
1643 case ExpressionEvaluationContext::PotentiallyEvaluated:
1644 case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
1649 return MaybeBindToTemporary(Lambda);
1652 ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
1653 SourceLocation ConvLocation,
1654 CXXConversionDecl *Conv,
1656 // Make sure that the lambda call operator is marked used.
1657 CXXRecordDecl *Lambda = Conv->getParent();
1658 CXXMethodDecl *CallOperator
1659 = cast<CXXMethodDecl>(
1661 Context.DeclarationNames.getCXXOperatorName(OO_Call)).front());
1662 CallOperator->setReferenced();
1663 CallOperator->markUsed(Context);
1665 ExprResult Init = PerformCopyInitialization(
1666 InitializedEntity::InitializeLambdaToBlock(ConvLocation, Src->getType(),
1668 CurrentLocation, Src);
1669 if (!Init.isInvalid())
1670 Init = ActOnFinishFullExpr(Init.get());
1672 if (Init.isInvalid())
1675 // Create the new block to be returned.
1676 BlockDecl *Block = BlockDecl::Create(Context, CurContext, ConvLocation);
1678 // Set the type information.
1679 Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
1680 Block->setIsVariadic(CallOperator->isVariadic());
1681 Block->setBlockMissingReturnType(false);
1684 SmallVector<ParmVarDecl *, 4> BlockParams;
1685 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1686 ParmVarDecl *From = CallOperator->getParamDecl(I);
1687 BlockParams.push_back(ParmVarDecl::Create(Context, Block,
1688 From->getLocStart(),
1689 From->getLocation(),
1690 From->getIdentifier(),
1692 From->getTypeSourceInfo(),
1693 From->getStorageClass(),
1694 /*DefaultArg=*/nullptr));
1696 Block->setParams(BlockParams);
1698 Block->setIsConversionFromLambda(true);
1700 // Add capture. The capture uses a fake variable, which doesn't correspond
1701 // to any actual memory location. However, the initializer copy-initializes
1702 // the lambda object.
1703 TypeSourceInfo *CapVarTSI =
1704 Context.getTrivialTypeSourceInfo(Src->getType());
1705 VarDecl *CapVar = VarDecl::Create(Context, Block, ConvLocation,
1706 ConvLocation, nullptr,
1707 Src->getType(), CapVarTSI,
1709 BlockDecl::Capture Capture(/*Variable=*/CapVar, /*ByRef=*/false,
1710 /*Nested=*/false, /*Copy=*/Init.get());
1711 Block->setCaptures(Context, Capture, /*CapturesCXXThis=*/false);
1713 // Add a fake function body to the block. IR generation is responsible
1714 // for filling in the actual body, which cannot be expressed as an AST.
1715 Block->setBody(new (Context) CompoundStmt(ConvLocation));
1717 // Create the block literal expression.
1718 Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
1719 ExprCleanupObjects.push_back(Block);
1720 Cleanup.setExprNeedsCleanups(true);