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;
294 // Default arguments of member function parameters that appear in a class
295 // definition, as well as the initializers of data members, receive special
296 // treatment. Identify them.
297 if (ManglingContextDecl) {
298 if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(ManglingContextDecl)) {
299 if (const DeclContext *LexicalDC
300 = Param->getDeclContext()->getLexicalParent())
301 if (LexicalDC->isRecord())
302 Kind = DefaultArgument;
303 } else if (VarDecl *Var = dyn_cast<VarDecl>(ManglingContextDecl)) {
304 if (Var->getDeclContext()->isRecord())
305 Kind = StaticDataMember;
306 } else if (isa<FieldDecl>(ManglingContextDecl)) {
311 // Itanium ABI [5.1.7]:
312 // In the following contexts [...] the one-definition rule requires closure
313 // types in different translation units to "correspond":
314 bool IsInNonspecializedTemplate =
315 !ActiveTemplateInstantiations.empty() || CurContext->isDependentContext();
318 // -- the bodies of non-exported nonspecialized template functions
319 // -- the bodies of inline functions
320 if ((IsInNonspecializedTemplate &&
321 !(ManglingContextDecl && isa<ParmVarDecl>(ManglingContextDecl))) ||
322 isInInlineFunction(CurContext)) {
323 ManglingContextDecl = nullptr;
324 while (auto *CD = dyn_cast<CapturedDecl>(DC))
325 DC = CD->getParent();
326 return &Context.getManglingNumberContext(DC);
329 ManglingContextDecl = nullptr;
333 case StaticDataMember:
334 // -- the initializers of nonspecialized static members of template classes
335 if (!IsInNonspecializedTemplate) {
336 ManglingContextDecl = nullptr;
339 // Fall through to get the current context.
342 // -- the in-class initializers of class members
343 case DefaultArgument:
344 // -- default arguments appearing in class definitions
345 return &ExprEvalContexts.back().getMangleNumberingContext(Context);
348 llvm_unreachable("unexpected context");
351 MangleNumberingContext &
352 Sema::ExpressionEvaluationContextRecord::getMangleNumberingContext(
354 assert(ManglingContextDecl && "Need to have a context declaration");
355 if (!MangleNumbering)
356 MangleNumbering = Ctx.createMangleNumberingContext();
357 return *MangleNumbering;
360 CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
361 SourceRange IntroducerRange,
362 TypeSourceInfo *MethodTypeInfo,
363 SourceLocation EndLoc,
364 ArrayRef<ParmVarDecl *> Params,
365 const bool IsConstexprSpecified) {
366 QualType MethodType = MethodTypeInfo->getType();
367 TemplateParameterList *TemplateParams =
368 getGenericLambdaTemplateParameterList(getCurLambda(), *this);
369 // If a lambda appears in a dependent context or is a generic lambda (has
370 // template parameters) and has an 'auto' return type, deduce it to a
372 if (Class->isDependentContext() || TemplateParams) {
373 const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
374 QualType Result = FPT->getReturnType();
375 if (Result->isUndeducedType()) {
376 Result = SubstAutoType(Result, Context.DependentTy);
377 MethodType = Context.getFunctionType(Result, FPT->getParamTypes(),
378 FPT->getExtProtoInfo());
382 // C++11 [expr.prim.lambda]p5:
383 // The closure type for a lambda-expression has a public inline function
384 // call operator (13.5.4) whose parameters and return type are described by
385 // the lambda-expression's parameter-declaration-clause and
386 // trailing-return-type respectively.
387 DeclarationName MethodName
388 = Context.DeclarationNames.getCXXOperatorName(OO_Call);
389 DeclarationNameLoc MethodNameLoc;
390 MethodNameLoc.CXXOperatorName.BeginOpNameLoc
391 = IntroducerRange.getBegin().getRawEncoding();
392 MethodNameLoc.CXXOperatorName.EndOpNameLoc
393 = IntroducerRange.getEnd().getRawEncoding();
394 CXXMethodDecl *Method
395 = CXXMethodDecl::Create(Context, Class, EndLoc,
396 DeclarationNameInfo(MethodName,
397 IntroducerRange.getBegin(),
399 MethodType, MethodTypeInfo,
402 IsConstexprSpecified,
404 Method->setAccess(AS_public);
406 // Temporarily set the lexical declaration context to the current
407 // context, so that the Scope stack matches the lexical nesting.
408 Method->setLexicalDeclContext(CurContext);
409 // Create a function template if we have a template parameter list
410 FunctionTemplateDecl *const TemplateMethod = TemplateParams ?
411 FunctionTemplateDecl::Create(Context, Class,
412 Method->getLocation(), MethodName,
415 if (TemplateMethod) {
416 TemplateMethod->setLexicalDeclContext(CurContext);
417 TemplateMethod->setAccess(AS_public);
418 Method->setDescribedFunctionTemplate(TemplateMethod);
422 if (!Params.empty()) {
423 Method->setParams(Params);
424 CheckParmsForFunctionDef(Params,
425 /*CheckParameterNames=*/false);
427 for (auto P : Method->parameters())
428 P->setOwningFunction(Method);
431 Decl *ManglingContextDecl;
432 if (MangleNumberingContext *MCtx =
433 getCurrentMangleNumberContext(Class->getDeclContext(),
434 ManglingContextDecl)) {
435 unsigned ManglingNumber = MCtx->getManglingNumber(Method);
436 Class->setLambdaMangling(ManglingNumber, ManglingContextDecl);
442 void Sema::buildLambdaScope(LambdaScopeInfo *LSI,
443 CXXMethodDecl *CallOperator,
444 SourceRange IntroducerRange,
445 LambdaCaptureDefault CaptureDefault,
446 SourceLocation CaptureDefaultLoc,
448 bool ExplicitResultType,
450 LSI->CallOperator = CallOperator;
451 CXXRecordDecl *LambdaClass = CallOperator->getParent();
452 LSI->Lambda = LambdaClass;
453 if (CaptureDefault == LCD_ByCopy)
454 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
455 else if (CaptureDefault == LCD_ByRef)
456 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
457 LSI->CaptureDefaultLoc = CaptureDefaultLoc;
458 LSI->IntroducerRange = IntroducerRange;
459 LSI->ExplicitParams = ExplicitParams;
460 LSI->Mutable = Mutable;
462 if (ExplicitResultType) {
463 LSI->ReturnType = CallOperator->getReturnType();
465 if (!LSI->ReturnType->isDependentType() &&
466 !LSI->ReturnType->isVoidType()) {
467 if (RequireCompleteType(CallOperator->getLocStart(), LSI->ReturnType,
468 diag::err_lambda_incomplete_result)) {
473 LSI->HasImplicitReturnType = true;
477 void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
478 LSI->finishedExplicitCaptures();
481 void Sema::addLambdaParameters(CXXMethodDecl *CallOperator, Scope *CurScope) {
482 // Introduce our parameters into the function scope
483 for (unsigned p = 0, NumParams = CallOperator->getNumParams();
484 p < NumParams; ++p) {
485 ParmVarDecl *Param = CallOperator->getParamDecl(p);
487 // If this has an identifier, add it to the scope stack.
488 if (CurScope && Param->getIdentifier()) {
489 CheckShadow(CurScope, Param);
491 PushOnScopeChains(Param, CurScope);
496 /// If this expression is an enumerator-like expression of some type
497 /// T, return the type T; otherwise, return null.
499 /// Pointer comparisons on the result here should always work because
500 /// it's derived from either the parent of an EnumConstantDecl
501 /// (i.e. the definition) or the declaration returned by
502 /// EnumType::getDecl() (i.e. the definition).
503 static EnumDecl *findEnumForBlockReturn(Expr *E) {
504 // An expression is an enumerator-like expression of type T if,
505 // ignoring parens and parens-like expressions:
506 E = E->IgnoreParens();
508 // - it is an enumerator whose enum type is T or
509 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
510 if (EnumConstantDecl *D
511 = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
512 return cast<EnumDecl>(D->getDeclContext());
517 // - it is a comma expression whose RHS is an enumerator-like
518 // expression of type T or
519 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
520 if (BO->getOpcode() == BO_Comma)
521 return findEnumForBlockReturn(BO->getRHS());
525 // - it is a statement-expression whose value expression is an
526 // enumerator-like expression of type T or
527 if (StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
528 if (Expr *last = dyn_cast_or_null<Expr>(SE->getSubStmt()->body_back()))
529 return findEnumForBlockReturn(last);
533 // - it is a ternary conditional operator (not the GNU ?:
534 // extension) whose second and third operands are
535 // enumerator-like expressions of type T or
536 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
537 if (EnumDecl *ED = findEnumForBlockReturn(CO->getTrueExpr()))
538 if (ED == findEnumForBlockReturn(CO->getFalseExpr()))
544 // - it is an implicit integral conversion applied to an
545 // enumerator-like expression of type T or
546 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
547 // We can sometimes see integral conversions in valid
548 // enumerator-like expressions.
549 if (ICE->getCastKind() == CK_IntegralCast)
550 return findEnumForBlockReturn(ICE->getSubExpr());
552 // Otherwise, just rely on the type.
555 // - it is an expression of that formal enum type.
556 if (const EnumType *ET = E->getType()->getAs<EnumType>()) {
557 return ET->getDecl();
564 /// Attempt to find a type T for which the returned expression of the
565 /// given statement is an enumerator-like expression of that type.
566 static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
567 if (Expr *retValue = ret->getRetValue())
568 return findEnumForBlockReturn(retValue);
572 /// Attempt to find a common type T for which all of the returned
573 /// expressions in a block are enumerator-like expressions of that
575 static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
576 ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
578 // Try to find one for the first return.
579 EnumDecl *ED = findEnumForBlockReturn(*i);
580 if (!ED) return nullptr;
582 // Check that the rest of the returns have the same enum.
583 for (++i; i != e; ++i) {
584 if (findEnumForBlockReturn(*i) != ED)
588 // Never infer an anonymous enum type.
589 if (!ED->hasNameForLinkage()) return nullptr;
594 /// Adjust the given return statements so that they formally return
595 /// the given type. It should require, at most, an IntegralCast.
596 static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
597 QualType returnType) {
598 for (ArrayRef<ReturnStmt*>::iterator
599 i = returns.begin(), e = returns.end(); i != e; ++i) {
600 ReturnStmt *ret = *i;
601 Expr *retValue = ret->getRetValue();
602 if (S.Context.hasSameType(retValue->getType(), returnType))
605 // Right now we only support integral fixup casts.
606 assert(returnType->isIntegralOrUnscopedEnumerationType());
607 assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
609 ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(retValue);
611 Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
612 E = ImplicitCastExpr::Create(S.Context, returnType, CK_IntegralCast,
613 E, /*base path*/ nullptr, VK_RValue);
615 cleanups->setSubExpr(E);
622 void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
623 assert(CSI.HasImplicitReturnType);
624 // If it was ever a placeholder, it had to been deduced to DependentTy.
625 assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
626 assert((!isa<LambdaScopeInfo>(CSI) || !getLangOpts().CPlusPlus14) &&
627 "lambda expressions use auto deduction in C++14 onwards");
629 // C++ core issue 975:
630 // If a lambda-expression does not include a trailing-return-type,
631 // it is as if the trailing-return-type denotes the following type:
632 // - if there are no return statements in the compound-statement,
633 // or all return statements return either an expression of type
634 // void or no expression or braced-init-list, the type void;
635 // - otherwise, if all return statements return an expression
636 // and the types of the returned expressions after
637 // lvalue-to-rvalue conversion (4.1 [conv.lval]),
638 // array-to-pointer conversion (4.2 [conv.array]), and
639 // function-to-pointer conversion (4.3 [conv.func]) are the
640 // same, that common type;
641 // - otherwise, the program is ill-formed.
643 // C++ core issue 1048 additionally removes top-level cv-qualifiers
644 // from the types of returned expressions to match the C++14 auto
647 // In addition, in blocks in non-C++ modes, if all of the return
648 // statements are enumerator-like expressions of some type T, where
649 // T has a name for linkage, then we infer the return type of the
650 // block to be that type.
652 // First case: no return statements, implicit void return type.
653 ASTContext &Ctx = getASTContext();
654 if (CSI.Returns.empty()) {
655 // It's possible there were simply no /valid/ return statements.
656 // In this case, the first one we found may have at least given us a type.
657 if (CSI.ReturnType.isNull())
658 CSI.ReturnType = Ctx.VoidTy;
662 // Second case: at least one return statement has dependent type.
663 // Delay type checking until instantiation.
664 assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
665 if (CSI.ReturnType->isDependentType())
668 // Try to apply the enum-fuzz rule.
669 if (!getLangOpts().CPlusPlus) {
670 assert(isa<BlockScopeInfo>(CSI));
671 const EnumDecl *ED = findCommonEnumForBlockReturns(CSI.Returns);
673 CSI.ReturnType = Context.getTypeDeclType(ED);
674 adjustBlockReturnsToEnum(*this, CSI.Returns, CSI.ReturnType);
679 // Third case: only one return statement. Don't bother doing extra work!
680 SmallVectorImpl<ReturnStmt*>::iterator I = CSI.Returns.begin(),
681 E = CSI.Returns.end();
685 // General case: many return statements.
686 // Check that they all have compatible return types.
688 // We require the return types to strictly match here.
689 // Note that we've already done the required promotions as part of
690 // processing the return statement.
691 for (; I != E; ++I) {
692 const ReturnStmt *RS = *I;
693 const Expr *RetE = RS->getRetValue();
695 QualType ReturnType =
696 (RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
697 if (Context.getCanonicalFunctionResultType(ReturnType) ==
698 Context.getCanonicalFunctionResultType(CSI.ReturnType))
701 // FIXME: This is a poor diagnostic for ReturnStmts without expressions.
702 // TODO: It's possible that the *first* return is the divergent one.
703 Diag(RS->getLocStart(),
704 diag::err_typecheck_missing_return_type_incompatible)
705 << ReturnType << CSI.ReturnType
706 << isa<LambdaScopeInfo>(CSI);
707 // Continue iterating so that we keep emitting diagnostics.
711 QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
716 // Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
718 QualType DeductType = Context.getAutoDeductType();
720 TLB.pushTypeSpec(DeductType).setNameLoc(Loc);
722 DeductType = BuildReferenceType(DeductType, true, Loc, Id);
723 assert(!DeductType.isNull() && "can't build reference to auto");
724 TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
726 TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
728 // Deduce the type of the init capture.
729 QualType DeducedType = deduceVarTypeFromInitializer(
730 /*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
731 SourceRange(Loc, Loc), IsDirectInit, Init);
732 if (DeducedType.isNull())
735 // Are we a non-list direct initialization?
736 ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
738 // Perform initialization analysis and ensure any implicit conversions
739 // (such as lvalue-to-rvalue) are enforced.
740 InitializedEntity Entity =
741 InitializedEntity::InitializeLambdaCapture(Id, DeducedType, Loc);
742 InitializationKind Kind =
744 ? (CXXDirectInit ? InitializationKind::CreateDirect(
745 Loc, Init->getLocStart(), Init->getLocEnd())
746 : InitializationKind::CreateDirectList(Loc))
747 : InitializationKind::CreateCopy(Loc, Init->getLocStart());
749 MultiExprArg Args = Init;
752 MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
754 InitializationSequence InitSeq(*this, Entity, Kind, Args);
755 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
757 if (Result.isInvalid())
759 Init = Result.getAs<Expr>();
761 // The init-capture initialization is a full-expression that must be
762 // processed as one before we enter the declcontext of the lambda's
764 Result = ActOnFinishFullExpr(Init, Loc, /*DiscardedValue*/ false,
765 /*IsConstexpr*/ false,
766 /*IsLambdaInitCaptureInitalizer*/ true);
767 if (Result.isInvalid())
770 Init = Result.getAs<Expr>();
774 VarDecl *Sema::createLambdaInitCaptureVarDecl(SourceLocation Loc,
775 QualType InitCaptureType,
777 unsigned InitStyle, Expr *Init) {
778 TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType,
780 // Create a dummy variable representing the init-capture. This is not actually
781 // used as a variable, and only exists as a way to name and refer to the
783 // FIXME: Pass in separate source locations for '&' and identifier.
784 VarDecl *NewVD = VarDecl::Create(Context, CurContext, Loc,
785 Loc, Id, InitCaptureType, TSI, SC_Auto);
786 NewVD->setInitCapture(true);
787 NewVD->setReferenced(true);
788 // FIXME: Pass in a VarDecl::InitializationStyle.
789 NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
790 NewVD->markUsed(Context);
791 NewVD->setInit(Init);
795 FieldDecl *Sema::buildInitCaptureField(LambdaScopeInfo *LSI, VarDecl *Var) {
796 FieldDecl *Field = FieldDecl::Create(
797 Context, LSI->Lambda, Var->getLocation(), Var->getLocation(),
798 nullptr, Var->getType(), Var->getTypeSourceInfo(), nullptr, false,
800 Field->setImplicit(true);
801 Field->setAccess(AS_private);
802 LSI->Lambda->addDecl(Field);
804 LSI->addCapture(Var, /*isBlock*/false, Var->getType()->isReferenceType(),
805 /*isNested*/false, Var->getLocation(), SourceLocation(),
806 Var->getType(), Var->getInit());
810 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
811 Declarator &ParamInfo,
813 // Determine if we're within a context where we know that the lambda will
814 // be dependent, because there are template parameters in scope.
815 bool KnownDependent = false;
816 LambdaScopeInfo *const LSI = getCurLambda();
817 assert(LSI && "LambdaScopeInfo should be on stack!");
819 // The lambda-expression's closure type might be dependent even if its
820 // semantic context isn't, if it appears within a default argument of a
821 // function template.
822 if (CurScope->getTemplateParamParent())
823 KnownDependent = true;
825 // Determine the signature of the call operator.
826 TypeSourceInfo *MethodTyInfo;
827 bool ExplicitParams = true;
828 bool ExplicitResultType = true;
829 bool ContainsUnexpandedParameterPack = false;
830 SourceLocation EndLoc;
831 SmallVector<ParmVarDecl *, 8> Params;
832 if (ParamInfo.getNumTypeObjects() == 0) {
833 // C++11 [expr.prim.lambda]p4:
834 // If a lambda-expression does not include a lambda-declarator, it is as
835 // if the lambda-declarator were ().
836 FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(
837 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
838 EPI.HasTrailingReturn = true;
839 EPI.TypeQuals |= DeclSpec::TQ_const;
840 // C++1y [expr.prim.lambda]:
841 // The lambda return type is 'auto', which is replaced by the
842 // trailing-return type if provided and/or deduced from 'return'
844 // We don't do this before C++1y, because we don't support deduced return
846 QualType DefaultTypeForNoTrailingReturn =
847 getLangOpts().CPlusPlus14 ? Context.getAutoDeductType()
848 : Context.DependentTy;
850 Context.getFunctionType(DefaultTypeForNoTrailingReturn, None, EPI);
851 MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy);
852 ExplicitParams = false;
853 ExplicitResultType = false;
854 EndLoc = Intro.Range.getEnd();
856 assert(ParamInfo.isFunctionDeclarator() &&
857 "lambda-declarator is a function");
858 DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
860 // C++11 [expr.prim.lambda]p5:
861 // This function call operator is declared const (9.3.1) if and only if
862 // the lambda-expression's parameter-declaration-clause is not followed
863 // by mutable. It is neither virtual nor declared volatile. [...]
864 if (!FTI.hasMutableQualifier())
865 FTI.TypeQuals |= DeclSpec::TQ_const;
867 MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope);
868 assert(MethodTyInfo && "no type from lambda-declarator");
869 EndLoc = ParamInfo.getSourceRange().getEnd();
871 ExplicitResultType = FTI.hasTrailingReturnType();
873 if (FTIHasNonVoidParameters(FTI)) {
874 Params.reserve(FTI.NumParams);
875 for (unsigned i = 0, e = FTI.NumParams; i != e; ++i)
876 Params.push_back(cast<ParmVarDecl>(FTI.Params[i].Param));
879 // Check for unexpanded parameter packs in the method type.
880 if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
881 ContainsUnexpandedParameterPack = true;
884 CXXRecordDecl *Class = createLambdaClosureType(Intro.Range, MethodTyInfo,
885 KnownDependent, Intro.Default);
887 CXXMethodDecl *Method =
888 startLambdaDefinition(Class, Intro.Range, MethodTyInfo, EndLoc, Params,
889 ParamInfo.getDeclSpec().isConstexprSpecified());
891 CheckCXXDefaultArguments(Method);
893 // Attributes on the lambda apply to the method.
894 ProcessDeclAttributes(CurScope, Method, ParamInfo);
896 // CUDA lambdas get implicit attributes based on the scope in which they're
898 if (getLangOpts().CUDA)
899 CUDASetLambdaAttrs(Method);
901 // Introduce the function call operator as the current declaration context.
902 PushDeclContext(CurScope, Method);
904 // Build the lambda scope.
905 buildLambdaScope(LSI, Method, Intro.Range, Intro.Default, Intro.DefaultLoc,
906 ExplicitParams, ExplicitResultType, !Method->isConst());
908 // C++11 [expr.prim.lambda]p9:
909 // A lambda-expression whose smallest enclosing scope is a block scope is a
910 // local lambda expression; any other lambda expression shall not have a
911 // capture-default or simple-capture in its lambda-introducer.
913 // For simple-captures, this is covered by the check below that any named
914 // entity is a variable that can be captured.
916 // For DR1632, we also allow a capture-default in any context where we can
917 // odr-use 'this' (in particular, in a default initializer for a non-static
919 if (Intro.Default != LCD_None && !Class->getParent()->isFunctionOrMethod() &&
920 (getCurrentThisType().isNull() ||
921 CheckCXXThisCapture(SourceLocation(), /*Explicit*/true,
922 /*BuildAndDiagnose*/false)))
923 Diag(Intro.DefaultLoc, diag::err_capture_default_non_local);
925 // Distinct capture names, for diagnostics.
926 llvm::SmallSet<IdentifierInfo*, 8> CaptureNames;
928 // Handle explicit captures.
929 SourceLocation PrevCaptureLoc
930 = Intro.Default == LCD_None? Intro.Range.getBegin() : Intro.DefaultLoc;
931 for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
932 PrevCaptureLoc = C->Loc, ++C) {
933 if (C->Kind == LCK_This || C->Kind == LCK_StarThis) {
934 if (C->Kind == LCK_StarThis)
935 Diag(C->Loc, !getLangOpts().CPlusPlus1z
936 ? diag::ext_star_this_lambda_capture_cxx1z
937 : diag::warn_cxx14_compat_star_this_lambda_capture);
939 // C++11 [expr.prim.lambda]p8:
940 // An identifier or this shall not appear more than once in a
942 if (LSI->isCXXThisCaptured()) {
943 Diag(C->Loc, diag::err_capture_more_than_once)
944 << "'this'" << SourceRange(LSI->getCXXThisCapture().getLocation())
945 << FixItHint::CreateRemoval(
946 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
950 // C++1z [expr.prim.lambda]p8:
951 // If a lambda-capture includes a capture-default that is =, each
952 // simple-capture of that lambda-capture shall be of the form "&
953 // identifier" or "* this". [ Note: The form [&,this] is redundant but
954 // accepted for compatibility with ISO C++14. --end note ]
955 if (Intro.Default == LCD_ByCopy && C->Kind != LCK_StarThis) {
956 Diag(C->Loc, diag::err_this_capture_with_copy_default)
957 << FixItHint::CreateRemoval(
958 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
962 // C++11 [expr.prim.lambda]p12:
963 // If this is captured by a local lambda expression, its nearest
964 // enclosing function shall be a non-static member function.
965 QualType ThisCaptureType = getCurrentThisType();
966 if (ThisCaptureType.isNull()) {
967 Diag(C->Loc, diag::err_this_capture) << true;
971 CheckCXXThisCapture(C->Loc, /*Explicit=*/true, /*BuildAndDiagnose*/ true,
972 /*FunctionScopeIndexToStopAtPtr*/ nullptr,
973 C->Kind == LCK_StarThis);
977 assert(C->Id && "missing identifier for capture");
979 if (C->Init.isInvalid())
982 VarDecl *Var = nullptr;
983 if (C->Init.isUsable()) {
984 Diag(C->Loc, getLangOpts().CPlusPlus14
985 ? diag::warn_cxx11_compat_init_capture
986 : diag::ext_init_capture);
988 if (C->Init.get()->containsUnexpandedParameterPack())
989 ContainsUnexpandedParameterPack = true;
990 // If the initializer expression is usable, but the InitCaptureType
991 // is not, then an error has occurred - so ignore the capture for now.
992 // for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
993 // FIXME: we should create the init capture variable and mark it invalid
995 if (C->InitCaptureType.get().isNull())
999 switch (C->InitKind) {
1000 case LambdaCaptureInitKind::NoInit:
1001 llvm_unreachable("not an init-capture?");
1002 case LambdaCaptureInitKind::CopyInit:
1003 InitStyle = VarDecl::CInit;
1005 case LambdaCaptureInitKind::DirectInit:
1006 InitStyle = VarDecl::CallInit;
1008 case LambdaCaptureInitKind::ListInit:
1009 InitStyle = VarDecl::ListInit;
1012 Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
1013 C->Id, InitStyle, C->Init.get());
1014 // C++1y [expr.prim.lambda]p11:
1015 // An init-capture behaves as if it declares and explicitly
1016 // captures a variable [...] whose declarative region is the
1017 // lambda-expression's compound-statement
1019 PushOnScopeChains(Var, CurScope, false);
1021 assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
1022 "init capture has valid but null init?");
1024 // C++11 [expr.prim.lambda]p8:
1025 // If a lambda-capture includes a capture-default that is &, the
1026 // identifiers in the lambda-capture shall not be preceded by &.
1027 // If a lambda-capture includes a capture-default that is =, [...]
1028 // each identifier it contains shall be preceded by &.
1029 if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
1030 Diag(C->Loc, diag::err_reference_capture_with_reference_default)
1031 << FixItHint::CreateRemoval(
1032 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1034 } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
1035 Diag(C->Loc, diag::err_copy_capture_with_copy_default)
1036 << FixItHint::CreateRemoval(
1037 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1041 // C++11 [expr.prim.lambda]p10:
1042 // The identifiers in a capture-list are looked up using the usual
1043 // rules for unqualified name lookup (3.4.1)
1044 DeclarationNameInfo Name(C->Id, C->Loc);
1045 LookupResult R(*this, Name, LookupOrdinaryName);
1046 LookupName(R, CurScope);
1047 if (R.isAmbiguous())
1050 // FIXME: Disable corrections that would add qualification?
1051 CXXScopeSpec ScopeSpec;
1052 if (DiagnoseEmptyLookup(CurScope, ScopeSpec, R,
1053 llvm::make_unique<DeclFilterCCC<VarDecl>>()))
1057 Var = R.getAsSingle<VarDecl>();
1058 if (Var && DiagnoseUseOfDecl(Var, C->Loc))
1062 // C++11 [expr.prim.lambda]p8:
1063 // An identifier or this shall not appear more than once in a
1065 if (!CaptureNames.insert(C->Id).second) {
1066 if (Var && LSI->isCaptured(Var)) {
1067 Diag(C->Loc, diag::err_capture_more_than_once)
1068 << C->Id << SourceRange(LSI->getCapture(Var).getLocation())
1069 << FixItHint::CreateRemoval(
1070 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1072 // Previous capture captured something different (one or both was
1073 // an init-cpature): no fixit.
1074 Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
1078 // C++11 [expr.prim.lambda]p10:
1079 // [...] each such lookup shall find a variable with automatic storage
1080 // duration declared in the reaching scope of the local lambda expression.
1081 // Note that the 'reaching scope' check happens in tryCaptureVariable().
1083 Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id;
1087 // Ignore invalid decls; they'll just confuse the code later.
1088 if (Var->isInvalidDecl())
1091 if (!Var->hasLocalStorage()) {
1092 Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id;
1093 Diag(Var->getLocation(), diag::note_previous_decl) << C->Id;
1097 // C++11 [expr.prim.lambda]p23:
1098 // A capture followed by an ellipsis is a pack expansion (14.5.3).
1099 SourceLocation EllipsisLoc;
1100 if (C->EllipsisLoc.isValid()) {
1101 if (Var->isParameterPack()) {
1102 EllipsisLoc = C->EllipsisLoc;
1104 Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
1105 << SourceRange(C->Loc);
1107 // Just ignore the ellipsis.
1109 } else if (Var->isParameterPack()) {
1110 ContainsUnexpandedParameterPack = true;
1113 if (C->Init.isUsable()) {
1114 buildInitCaptureField(LSI, Var);
1116 TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef :
1117 TryCapture_ExplicitByVal;
1118 tryCaptureVariable(Var, C->Loc, Kind, EllipsisLoc);
1121 finishLambdaExplicitCaptures(LSI);
1123 LSI->ContainsUnexpandedParameterPack = ContainsUnexpandedParameterPack;
1125 // Add lambda parameters into scope.
1126 addLambdaParameters(Method, CurScope);
1128 // Enter a new evaluation context to insulate the lambda from any
1129 // cleanups from the enclosing full-expression.
1130 PushExpressionEvaluationContext(PotentiallyEvaluated);
1133 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
1134 bool IsInstantiation) {
1135 LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
1137 // Leave the expression-evaluation context.
1138 DiscardCleanupsInEvaluationContext();
1139 PopExpressionEvaluationContext();
1141 // Leave the context of the lambda.
1142 if (!IsInstantiation)
1145 // Finalize the lambda.
1146 CXXRecordDecl *Class = LSI->Lambda;
1147 Class->setInvalidDecl();
1148 SmallVector<Decl*, 4> Fields(Class->fields());
1149 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1150 SourceLocation(), nullptr);
1151 CheckCompletedCXXClass(Class);
1153 PopFunctionScopeInfo();
1156 /// \brief Add a lambda's conversion to function pointer, as described in
1157 /// C++11 [expr.prim.lambda]p6.
1158 static void addFunctionPointerConversion(Sema &S,
1159 SourceRange IntroducerRange,
1160 CXXRecordDecl *Class,
1161 CXXMethodDecl *CallOperator) {
1162 // This conversion is explicitly disabled if the lambda's function has
1163 // pass_object_size attributes on any of its parameters.
1164 auto HasPassObjectSizeAttr = [](const ParmVarDecl *P) {
1165 return P->hasAttr<PassObjectSizeAttr>();
1167 if (llvm::any_of(CallOperator->parameters(), HasPassObjectSizeAttr))
1170 // Add the conversion to function pointer.
1171 const FunctionProtoType *CallOpProto =
1172 CallOperator->getType()->getAs<FunctionProtoType>();
1173 const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
1174 CallOpProto->getExtProtoInfo();
1175 QualType PtrToFunctionTy;
1176 QualType InvokerFunctionTy;
1178 FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
1179 CallingConv CC = S.Context.getDefaultCallingConvention(
1180 CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
1181 InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(CC);
1182 InvokerExtInfo.TypeQuals = 0;
1183 assert(InvokerExtInfo.RefQualifier == RQ_None &&
1184 "Lambda's call operator should not have a reference qualifier");
1186 S.Context.getFunctionType(CallOpProto->getReturnType(),
1187 CallOpProto->getParamTypes(), InvokerExtInfo);
1188 PtrToFunctionTy = S.Context.getPointerType(InvokerFunctionTy);
1191 // Create the type of the conversion function.
1192 FunctionProtoType::ExtProtoInfo ConvExtInfo(
1193 S.Context.getDefaultCallingConvention(
1194 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1195 // The conversion function is always const.
1196 ConvExtInfo.TypeQuals = Qualifiers::Const;
1198 S.Context.getFunctionType(PtrToFunctionTy, None, ConvExtInfo);
1200 SourceLocation Loc = IntroducerRange.getBegin();
1201 DeclarationName ConversionName
1202 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1203 S.Context.getCanonicalType(PtrToFunctionTy));
1204 DeclarationNameLoc ConvNameLoc;
1205 // Construct a TypeSourceInfo for the conversion function, and wire
1206 // all the parameters appropriately for the FunctionProtoTypeLoc
1207 // so that everything works during transformation/instantiation of
1209 // The main reason for wiring up the parameters of the conversion
1210 // function with that of the call operator is so that constructs
1211 // like the following work:
1212 // auto L = [](auto b) { <-- 1
1213 // return [](auto a) -> decltype(a) { <-- 2
1217 // int (*fp)(int) = L(5);
1218 // Because the trailing return type can contain DeclRefExprs that refer
1219 // to the original call operator's variables, we hijack the call
1220 // operators ParmVarDecls below.
1221 TypeSourceInfo *ConvNamePtrToFunctionTSI =
1222 S.Context.getTrivialTypeSourceInfo(PtrToFunctionTy, Loc);
1223 ConvNameLoc.NamedType.TInfo = ConvNamePtrToFunctionTSI;
1225 // The conversion function is a conversion to a pointer-to-function.
1226 TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(ConvTy, Loc);
1227 FunctionProtoTypeLoc ConvTL =
1228 ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
1229 // Get the result of the conversion function which is a pointer-to-function.
1230 PointerTypeLoc PtrToFunctionTL =
1231 ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
1232 // Do the same for the TypeSourceInfo that is used to name the conversion
1234 PointerTypeLoc ConvNamePtrToFunctionTL =
1235 ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
1237 // Get the underlying function types that the conversion function will
1238 // be converting to (should match the type of the call operator).
1239 FunctionProtoTypeLoc CallOpConvTL =
1240 PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1241 FunctionProtoTypeLoc CallOpConvNameTL =
1242 ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1244 // Wire up the FunctionProtoTypeLocs with the call operator's parameters.
1245 // These parameter's are essentially used to transform the name and
1246 // the type of the conversion operator. By using the same parameters
1247 // as the call operator's we don't have to fix any back references that
1248 // the trailing return type of the call operator's uses (such as
1249 // decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
1250 // - we can simply use the return type of the call operator, and
1251 // everything should work.
1252 SmallVector<ParmVarDecl *, 4> InvokerParams;
1253 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1254 ParmVarDecl *From = CallOperator->getParamDecl(I);
1256 InvokerParams.push_back(ParmVarDecl::Create(S.Context,
1257 // Temporarily add to the TU. This is set to the invoker below.
1258 S.Context.getTranslationUnitDecl(),
1259 From->getLocStart(),
1260 From->getLocation(),
1261 From->getIdentifier(),
1263 From->getTypeSourceInfo(),
1264 From->getStorageClass(),
1265 /*DefaultArg=*/nullptr));
1266 CallOpConvTL.setParam(I, From);
1267 CallOpConvNameTL.setParam(I, From);
1270 CXXConversionDecl *Conversion
1271 = CXXConversionDecl::Create(S.Context, Class, Loc,
1272 DeclarationNameInfo(ConversionName,
1276 /*isInline=*/true, /*isExplicit=*/false,
1277 /*isConstexpr=*/S.getLangOpts().CPlusPlus1z,
1278 CallOperator->getBody()->getLocEnd());
1279 Conversion->setAccess(AS_public);
1280 Conversion->setImplicit(true);
1282 if (Class->isGenericLambda()) {
1283 // Create a template version of the conversion operator, using the template
1284 // parameter list of the function call operator.
1285 FunctionTemplateDecl *TemplateCallOperator =
1286 CallOperator->getDescribedFunctionTemplate();
1287 FunctionTemplateDecl *ConversionTemplate =
1288 FunctionTemplateDecl::Create(S.Context, Class,
1289 Loc, ConversionName,
1290 TemplateCallOperator->getTemplateParameters(),
1292 ConversionTemplate->setAccess(AS_public);
1293 ConversionTemplate->setImplicit(true);
1294 Conversion->setDescribedFunctionTemplate(ConversionTemplate);
1295 Class->addDecl(ConversionTemplate);
1297 Class->addDecl(Conversion);
1298 // Add a non-static member function that will be the result of
1299 // the conversion with a certain unique ID.
1300 DeclarationName InvokerName = &S.Context.Idents.get(
1301 getLambdaStaticInvokerName());
1302 // FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
1303 // we should get a prebuilt TrivialTypeSourceInfo from Context
1304 // using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
1305 // then rewire the parameters accordingly, by hoisting up the InvokeParams
1306 // loop below and then use its Params to set Invoke->setParams(...) below.
1307 // This would avoid the 'const' qualifier of the calloperator from
1308 // contaminating the type of the invoker, which is currently adjusted
1309 // in SemaTemplateDeduction.cpp:DeduceTemplateArguments. Fixing the
1310 // trailing return type of the invoker would require a visitor to rebuild
1311 // the trailing return type and adjusting all back DeclRefExpr's to refer
1312 // to the new static invoker parameters - not the call operator's.
1313 CXXMethodDecl *Invoke
1314 = CXXMethodDecl::Create(S.Context, Class, Loc,
1315 DeclarationNameInfo(InvokerName, Loc),
1317 CallOperator->getTypeSourceInfo(),
1318 SC_Static, /*IsInline=*/true,
1319 /*IsConstexpr=*/false,
1320 CallOperator->getBody()->getLocEnd());
1321 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
1322 InvokerParams[I]->setOwningFunction(Invoke);
1323 Invoke->setParams(InvokerParams);
1324 Invoke->setAccess(AS_private);
1325 Invoke->setImplicit(true);
1326 if (Class->isGenericLambda()) {
1327 FunctionTemplateDecl *TemplateCallOperator =
1328 CallOperator->getDescribedFunctionTemplate();
1329 FunctionTemplateDecl *StaticInvokerTemplate = FunctionTemplateDecl::Create(
1330 S.Context, Class, Loc, InvokerName,
1331 TemplateCallOperator->getTemplateParameters(),
1333 StaticInvokerTemplate->setAccess(AS_private);
1334 StaticInvokerTemplate->setImplicit(true);
1335 Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
1336 Class->addDecl(StaticInvokerTemplate);
1338 Class->addDecl(Invoke);
1341 /// \brief Add a lambda's conversion to block pointer.
1342 static void addBlockPointerConversion(Sema &S,
1343 SourceRange IntroducerRange,
1344 CXXRecordDecl *Class,
1345 CXXMethodDecl *CallOperator) {
1346 const FunctionProtoType *Proto =
1347 CallOperator->getType()->getAs<FunctionProtoType>();
1349 // The function type inside the block pointer type is the same as the call
1350 // operator with some tweaks. The calling convention is the default free
1351 // function convention, and the type qualifications are lost.
1352 FunctionProtoType::ExtProtoInfo BlockEPI = Proto->getExtProtoInfo();
1354 BlockEPI.ExtInfo.withCallingConv(S.Context.getDefaultCallingConvention(
1355 Proto->isVariadic(), /*IsCXXMethod=*/false));
1356 BlockEPI.TypeQuals = 0;
1357 QualType FunctionTy = S.Context.getFunctionType(
1358 Proto->getReturnType(), Proto->getParamTypes(), BlockEPI);
1359 QualType BlockPtrTy = S.Context.getBlockPointerType(FunctionTy);
1361 FunctionProtoType::ExtProtoInfo ConversionEPI(
1362 S.Context.getDefaultCallingConvention(
1363 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1364 ConversionEPI.TypeQuals = Qualifiers::Const;
1365 QualType ConvTy = S.Context.getFunctionType(BlockPtrTy, None, ConversionEPI);
1367 SourceLocation Loc = IntroducerRange.getBegin();
1368 DeclarationName Name
1369 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1370 S.Context.getCanonicalType(BlockPtrTy));
1371 DeclarationNameLoc NameLoc;
1372 NameLoc.NamedType.TInfo = S.Context.getTrivialTypeSourceInfo(BlockPtrTy, Loc);
1373 CXXConversionDecl *Conversion
1374 = CXXConversionDecl::Create(S.Context, Class, Loc,
1375 DeclarationNameInfo(Name, Loc, NameLoc),
1377 S.Context.getTrivialTypeSourceInfo(ConvTy, Loc),
1378 /*isInline=*/true, /*isExplicit=*/false,
1379 /*isConstexpr=*/false,
1380 CallOperator->getBody()->getLocEnd());
1381 Conversion->setAccess(AS_public);
1382 Conversion->setImplicit(true);
1383 Class->addDecl(Conversion);
1386 static ExprResult performLambdaVarCaptureInitialization(
1387 Sema &S, LambdaScopeInfo::Capture &Capture, FieldDecl *Field) {
1388 assert(Capture.isVariableCapture() && "not a variable capture");
1390 auto *Var = Capture.getVariable();
1391 SourceLocation Loc = Capture.getLocation();
1393 // C++11 [expr.prim.lambda]p21:
1394 // When the lambda-expression is evaluated, the entities that
1395 // are captured by copy are used to direct-initialize each
1396 // corresponding non-static data member of the resulting closure
1397 // object. (For array members, the array elements are
1398 // direct-initialized in increasing subscript order.) These
1399 // initializations are performed in the (unspecified) order in
1400 // which the non-static data members are declared.
1402 // C++ [expr.prim.lambda]p12:
1403 // An entity captured by a lambda-expression is odr-used (3.2) in
1404 // the scope containing the lambda-expression.
1405 ExprResult RefResult = S.BuildDeclarationNameExpr(
1406 CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
1407 if (RefResult.isInvalid())
1409 Expr *Ref = RefResult.get();
1411 auto Entity = InitializedEntity::InitializeLambdaCapture(
1412 Var->getIdentifier(), Field->getType(), Loc);
1413 InitializationKind InitKind = InitializationKind::CreateDirect(Loc, Loc, Loc);
1414 InitializationSequence Init(S, Entity, InitKind, Ref);
1415 return Init.Perform(S, Entity, InitKind, Ref);
1418 ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
1420 LambdaScopeInfo LSI = *cast<LambdaScopeInfo>(FunctionScopes.back());
1421 ActOnFinishFunctionBody(LSI.CallOperator, Body);
1422 return BuildLambdaExpr(StartLoc, Body->getLocEnd(), &LSI);
1425 static LambdaCaptureDefault
1426 mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
1428 case CapturingScopeInfo::ImpCap_None:
1430 case CapturingScopeInfo::ImpCap_LambdaByval:
1432 case CapturingScopeInfo::ImpCap_CapturedRegion:
1433 case CapturingScopeInfo::ImpCap_LambdaByref:
1435 case CapturingScopeInfo::ImpCap_Block:
1436 llvm_unreachable("block capture in lambda");
1438 llvm_unreachable("Unknown implicit capture style");
1441 ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
1442 LambdaScopeInfo *LSI) {
1443 // Collect information from the lambda scope.
1444 SmallVector<LambdaCapture, 4> Captures;
1445 SmallVector<Expr *, 4> CaptureInits;
1446 SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
1447 LambdaCaptureDefault CaptureDefault =
1448 mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
1449 CXXRecordDecl *Class;
1450 CXXMethodDecl *CallOperator;
1451 SourceRange IntroducerRange;
1452 bool ExplicitParams;
1453 bool ExplicitResultType;
1454 CleanupInfo LambdaCleanup;
1455 bool ContainsUnexpandedParameterPack;
1457 CallOperator = LSI->CallOperator;
1458 Class = LSI->Lambda;
1459 IntroducerRange = LSI->IntroducerRange;
1460 ExplicitParams = LSI->ExplicitParams;
1461 ExplicitResultType = !LSI->HasImplicitReturnType;
1462 LambdaCleanup = LSI->Cleanup;
1463 ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
1465 CallOperator->setLexicalDeclContext(Class);
1466 Decl *TemplateOrNonTemplateCallOperatorDecl =
1467 CallOperator->getDescribedFunctionTemplate()
1468 ? CallOperator->getDescribedFunctionTemplate()
1469 : cast<Decl>(CallOperator);
1471 TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
1472 Class->addDecl(TemplateOrNonTemplateCallOperatorDecl);
1474 PopExpressionEvaluationContext();
1476 // Translate captures.
1477 auto CurField = Class->field_begin();
1478 for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I, ++CurField) {
1479 LambdaScopeInfo::Capture From = LSI->Captures[I];
1480 assert(!From.isBlockCapture() && "Cannot capture __block variables");
1481 bool IsImplicit = I >= LSI->NumExplicitCaptures;
1483 // Handle 'this' capture.
1484 if (From.isThisCapture()) {
1486 LambdaCapture(From.getLocation(), IsImplicit,
1487 From.isCopyCapture() ? LCK_StarThis : LCK_This));
1488 CaptureInits.push_back(From.getInitExpr());
1491 if (From.isVLATypeCapture()) {
1493 LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType));
1494 CaptureInits.push_back(nullptr);
1498 VarDecl *Var = From.getVariable();
1499 LambdaCaptureKind Kind = From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
1500 Captures.push_back(LambdaCapture(From.getLocation(), IsImplicit, Kind,
1501 Var, From.getEllipsisLoc()));
1502 Expr *Init = From.getInitExpr();
1505 performLambdaVarCaptureInitialization(*this, From, *CurField);
1506 if (InitResult.isInvalid())
1508 Init = InitResult.get();
1510 CaptureInits.push_back(Init);
1513 // C++11 [expr.prim.lambda]p6:
1514 // The closure type for a lambda-expression with no lambda-capture
1515 // has a public non-virtual non-explicit const conversion function
1516 // to pointer to function having the same parameter and return
1517 // types as the closure type's function call operator.
1518 if (Captures.empty() && CaptureDefault == LCD_None)
1519 addFunctionPointerConversion(*this, IntroducerRange, Class,
1523 // The closure type for a lambda-expression has a public non-virtual
1524 // non-explicit const conversion function to a block pointer having the
1525 // same parameter and return types as the closure type's function call
1527 // FIXME: Fix generic lambda to block conversions.
1528 if (getLangOpts().Blocks && getLangOpts().ObjC1 &&
1529 !Class->isGenericLambda())
1530 addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
1532 // Finalize the lambda class.
1533 SmallVector<Decl*, 4> Fields(Class->fields());
1534 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1535 SourceLocation(), nullptr);
1536 CheckCompletedCXXClass(Class);
1539 Cleanup.mergeFrom(LambdaCleanup);
1541 LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange,
1542 CaptureDefault, CaptureDefaultLoc,
1544 ExplicitParams, ExplicitResultType,
1545 CaptureInits, EndLoc,
1546 ContainsUnexpandedParameterPack);
1547 // If the lambda expression's call operator is not explicitly marked constexpr
1548 // and we are not in a dependent context, analyze the call operator to infer
1549 // its constexpr-ness, supressing diagnostics while doing so.
1550 if (getLangOpts().CPlusPlus1z && !CallOperator->isInvalidDecl() &&
1551 !CallOperator->isConstexpr() &&
1552 !Class->getDeclContext()->isDependentContext()) {
1553 TentativeAnalysisScope DiagnosticScopeGuard(*this);
1554 CallOperator->setConstexpr(
1555 CheckConstexprFunctionDecl(CallOperator) &&
1556 CheckConstexprFunctionBody(CallOperator, CallOperator->getBody()));
1559 // Emit delayed shadowing warnings now that the full capture list is known.
1560 DiagnoseShadowingLambdaDecls(LSI);
1562 if (!CurContext->isDependentContext()) {
1563 switch (ExprEvalContexts.back().Context) {
1564 // C++11 [expr.prim.lambda]p2:
1565 // A lambda-expression shall not appear in an unevaluated operand
1568 case UnevaluatedList:
1569 case UnevaluatedAbstract:
1570 // C++1y [expr.const]p2:
1571 // A conditional-expression e is a core constant expression unless the
1572 // evaluation of e, following the rules of the abstract machine, would
1573 // evaluate [...] a lambda-expression.
1575 // This is technically incorrect, there are some constant evaluated contexts
1576 // where this should be allowed. We should probably fix this when DR1607 is
1577 // ratified, it lays out the exact set of conditions where we shouldn't
1578 // allow a lambda-expression.
1579 case ConstantEvaluated:
1580 // We don't actually diagnose this case immediately, because we
1581 // could be within a context where we might find out later that
1582 // the expression is potentially evaluated (e.g., for typeid).
1583 ExprEvalContexts.back().Lambdas.push_back(Lambda);
1586 case DiscardedStatement:
1587 case PotentiallyEvaluated:
1588 case PotentiallyEvaluatedIfUsed:
1593 return MaybeBindToTemporary(Lambda);
1596 ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
1597 SourceLocation ConvLocation,
1598 CXXConversionDecl *Conv,
1600 // Make sure that the lambda call operator is marked used.
1601 CXXRecordDecl *Lambda = Conv->getParent();
1602 CXXMethodDecl *CallOperator
1603 = cast<CXXMethodDecl>(
1605 Context.DeclarationNames.getCXXOperatorName(OO_Call)).front());
1606 CallOperator->setReferenced();
1607 CallOperator->markUsed(Context);
1609 ExprResult Init = PerformCopyInitialization(
1610 InitializedEntity::InitializeBlock(ConvLocation,
1613 CurrentLocation, Src);
1614 if (!Init.isInvalid())
1615 Init = ActOnFinishFullExpr(Init.get());
1617 if (Init.isInvalid())
1620 // Create the new block to be returned.
1621 BlockDecl *Block = BlockDecl::Create(Context, CurContext, ConvLocation);
1623 // Set the type information.
1624 Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
1625 Block->setIsVariadic(CallOperator->isVariadic());
1626 Block->setBlockMissingReturnType(false);
1629 SmallVector<ParmVarDecl *, 4> BlockParams;
1630 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1631 ParmVarDecl *From = CallOperator->getParamDecl(I);
1632 BlockParams.push_back(ParmVarDecl::Create(Context, Block,
1633 From->getLocStart(),
1634 From->getLocation(),
1635 From->getIdentifier(),
1637 From->getTypeSourceInfo(),
1638 From->getStorageClass(),
1639 /*DefaultArg=*/nullptr));
1641 Block->setParams(BlockParams);
1643 Block->setIsConversionFromLambda(true);
1645 // Add capture. The capture uses a fake variable, which doesn't correspond
1646 // to any actual memory location. However, the initializer copy-initializes
1647 // the lambda object.
1648 TypeSourceInfo *CapVarTSI =
1649 Context.getTrivialTypeSourceInfo(Src->getType());
1650 VarDecl *CapVar = VarDecl::Create(Context, Block, ConvLocation,
1651 ConvLocation, nullptr,
1652 Src->getType(), CapVarTSI,
1654 BlockDecl::Capture Capture(/*Variable=*/CapVar, /*ByRef=*/false,
1655 /*Nested=*/false, /*Copy=*/Init.get());
1656 Block->setCaptures(Context, Capture, /*CapturesCXXThis=*/false);
1658 // Add a fake function body to the block. IR generation is responsible
1659 // for filling in the actual body, which cannot be expressed as an AST.
1660 Block->setBody(new (Context) CompoundStmt(ConvLocation));
1662 // Create the block literal expression.
1663 Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
1664 ExprCleanupObjects.push_back(Block);
1665 Cleanup.setExprNeedsCleanups(true);