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;
70 isa<clang::sema::LambdaScopeInfo>(
71 FunctionScopes[FunctionScopes.size() - 1]) &&
72 "The function on the top of sema's function-info stack must be a lambda");
74 // If VarToCapture is null, we are attempting to capture 'this'.
75 const bool IsCapturingThis = !VarToCapture;
76 const bool IsCapturingVariable = !IsCapturingThis;
78 // Start with the current lambda at the top of the stack (highest index).
79 unsigned CurScopeIndex = FunctionScopes.size() - 1;
80 DeclContext *EnclosingDC =
81 cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex])->CallOperator;
84 const clang::sema::LambdaScopeInfo *LSI =
85 cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]);
86 // IF we have climbed down to an intervening enclosing lambda that contains
87 // the variable declaration - it obviously can/must not capture the
89 // Since its enclosing DC is dependent, all the lambdas between it and the
90 // innermost nested lambda are dependent (otherwise we wouldn't have
91 // arrived here) - so we don't yet have a lambda that can capture the
93 if (IsCapturingVariable &&
94 VarToCapture->getDeclContext()->Equals(EnclosingDC))
95 return NoLambdaIsCaptureReady;
97 // For an enclosing lambda to be capture ready for an entity, all
98 // intervening lambda's have to be able to capture that entity. If even
99 // one of the intervening lambda's is not capable of capturing the entity
100 // then no enclosing lambda can ever capture that entity.
104 // [](auto b) { #2 <-- an intervening lambda that can never capture 'x'
106 // f(x, c); <-- can not lead to x's speculative capture by #1 or #2
108 // If they do not have a default implicit capture, check to see
109 // if the entity has already been explicitly captured.
110 // If even a single dependent enclosing lambda lacks the capability
111 // to ever capture this variable, there is no further enclosing
112 // non-dependent lambda that can capture this variable.
113 if (LSI->ImpCaptureStyle == sema::LambdaScopeInfo::ImpCap_None) {
114 if (IsCapturingVariable && !LSI->isCaptured(VarToCapture))
115 return NoLambdaIsCaptureReady;
116 if (IsCapturingThis && !LSI->isCXXThisCaptured())
117 return NoLambdaIsCaptureReady;
119 EnclosingDC = getLambdaAwareParentOfDeclContext(EnclosingDC);
121 assert(CurScopeIndex);
123 } while (!EnclosingDC->isTranslationUnit() &&
124 EnclosingDC->isDependentContext() &&
125 isLambdaCallOperator(EnclosingDC));
127 assert(CurScopeIndex < (FunctionScopes.size() - 1));
128 // If the enclosingDC is not dependent, then the immediately nested lambda
129 // (one index above) is capture-ready.
130 if (!EnclosingDC->isDependentContext())
131 return CurScopeIndex + 1;
132 return NoLambdaIsCaptureReady;
135 /// \brief Examines the FunctionScopeInfo stack to determine the nearest
136 /// enclosing lambda (to the current lambda) that is 'capture-capable' for
137 /// the variable referenced in the current lambda (i.e. \p VarToCapture).
138 /// If successful, returns the index into Sema's FunctionScopeInfo stack
139 /// of the capture-capable lambda's LambdaScopeInfo.
141 /// Given the current stack of lambdas being processed by Sema and
142 /// the variable of interest, to identify the nearest enclosing lambda (to the
143 /// current lambda at the top of the stack) that can truly capture
144 /// a variable, it has to have the following two properties:
145 /// a) 'capture-ready' - be the innermost lambda that is 'capture-ready':
146 /// - climb down the stack (i.e. starting from the innermost and examining
147 /// each outer lambda step by step) checking if each enclosing
148 /// lambda can either implicitly or explicitly capture the variable.
149 /// Record the first such lambda that is enclosed in a non-dependent
150 /// context. If no such lambda currently exists return failure.
151 /// b) 'capture-capable' - make sure the 'capture-ready' lambda can truly
152 /// capture the variable by checking all its enclosing lambdas:
153 /// - check if all outer lambdas enclosing the 'capture-ready' lambda
154 /// identified above in 'a' can also capture the variable (this is done
155 /// via tryCaptureVariable for variables and CheckCXXThisCapture for
156 /// 'this' by passing in the index of the Lambda identified in step 'a')
158 /// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
159 /// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
160 /// is at the top of the stack.
162 /// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
165 /// \returns An Optional<unsigned> Index that if evaluates to 'true' contains
166 /// the index (into Sema's FunctionScopeInfo stack) of the innermost lambda
167 /// which is capture-capable. If the return value evaluates to 'false' then
168 /// no lambda is capture-capable for \p VarToCapture.
170 Optional<unsigned> clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
171 ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
172 VarDecl *VarToCapture, Sema &S) {
174 const Optional<unsigned> NoLambdaIsCaptureCapable;
176 const Optional<unsigned> OptionalStackIndex =
177 getStackIndexOfNearestEnclosingCaptureReadyLambda(FunctionScopes,
179 if (!OptionalStackIndex)
180 return NoLambdaIsCaptureCapable;
182 const unsigned IndexOfCaptureReadyLambda = OptionalStackIndex.getValue();
183 assert(((IndexOfCaptureReadyLambda != (FunctionScopes.size() - 1)) ||
184 S.getCurGenericLambda()) &&
185 "The capture ready lambda for a potential capture can only be the "
186 "current lambda if it is a generic lambda");
188 const sema::LambdaScopeInfo *const CaptureReadyLambdaLSI =
189 cast<sema::LambdaScopeInfo>(FunctionScopes[IndexOfCaptureReadyLambda]);
191 // If VarToCapture is null, we are attempting to capture 'this'
192 const bool IsCapturingThis = !VarToCapture;
193 const bool IsCapturingVariable = !IsCapturingThis;
195 if (IsCapturingVariable) {
196 // Check if the capture-ready lambda can truly capture the variable, by
197 // checking whether all enclosing lambdas of the capture-ready lambda allow
198 // the capture - i.e. make sure it is capture-capable.
199 QualType CaptureType, DeclRefType;
200 const bool CanCaptureVariable =
201 !S.tryCaptureVariable(VarToCapture,
202 /*ExprVarIsUsedInLoc*/ SourceLocation(),
203 clang::Sema::TryCapture_Implicit,
204 /*EllipsisLoc*/ SourceLocation(),
205 /*BuildAndDiagnose*/ false, CaptureType,
206 DeclRefType, &IndexOfCaptureReadyLambda);
207 if (!CanCaptureVariable)
208 return NoLambdaIsCaptureCapable;
210 // Check if the capture-ready lambda can truly capture 'this' by checking
211 // whether all enclosing lambdas of the capture-ready lambda can capture
213 const bool CanCaptureThis =
214 !S.CheckCXXThisCapture(
215 CaptureReadyLambdaLSI->PotentialThisCaptureLocation,
216 /*Explicit*/ false, /*BuildAndDiagnose*/ false,
217 &IndexOfCaptureReadyLambda);
219 return NoLambdaIsCaptureCapable;
221 return IndexOfCaptureReadyLambda;
224 static inline TemplateParameterList *
225 getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) {
226 if (LSI->GLTemplateParameterList)
227 return LSI->GLTemplateParameterList;
229 if (!LSI->AutoTemplateParams.empty()) {
230 SourceRange IntroRange = LSI->IntroducerRange;
231 SourceLocation LAngleLoc = IntroRange.getBegin();
232 SourceLocation RAngleLoc = IntroRange.getEnd();
233 LSI->GLTemplateParameterList = TemplateParameterList::Create(
235 /*Template kw loc*/ SourceLocation(), LAngleLoc,
236 llvm::makeArrayRef((NamedDecl *const *)LSI->AutoTemplateParams.data(),
237 LSI->AutoTemplateParams.size()),
240 return LSI->GLTemplateParameterList;
243 CXXRecordDecl *Sema::createLambdaClosureType(SourceRange IntroducerRange,
244 TypeSourceInfo *Info,
246 LambdaCaptureDefault CaptureDefault) {
247 DeclContext *DC = CurContext;
248 while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
249 DC = DC->getParent();
250 bool IsGenericLambda = getGenericLambdaTemplateParameterList(getCurLambda(),
252 // Start constructing the lambda class.
253 CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(Context, DC, Info,
254 IntroducerRange.getBegin(),
263 /// \brief Determine whether the given context is or is enclosed in an inline
265 static bool isInInlineFunction(const DeclContext *DC) {
266 while (!DC->isFileContext()) {
267 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
271 DC = DC->getLexicalParent();
277 MangleNumberingContext *
278 Sema::getCurrentMangleNumberContext(const DeclContext *DC,
279 Decl *&ManglingContextDecl) {
280 // Compute the context for allocating mangling numbers in the current
281 // expression, if the ABI requires them.
282 ManglingContextDecl = ExprEvalContexts.back().ManglingContextDecl;
291 // Default arguments of member function parameters that appear in a class
292 // definition, as well as the initializers of data members, receive special
293 // treatment. Identify them.
294 if (ManglingContextDecl) {
295 if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(ManglingContextDecl)) {
296 if (const DeclContext *LexicalDC
297 = Param->getDeclContext()->getLexicalParent())
298 if (LexicalDC->isRecord())
299 Kind = DefaultArgument;
300 } else if (VarDecl *Var = dyn_cast<VarDecl>(ManglingContextDecl)) {
301 if (Var->getDeclContext()->isRecord())
302 Kind = StaticDataMember;
303 } else if (isa<FieldDecl>(ManglingContextDecl)) {
308 // Itanium ABI [5.1.7]:
309 // In the following contexts [...] the one-definition rule requires closure
310 // types in different translation units to "correspond":
311 bool IsInNonspecializedTemplate =
312 !ActiveTemplateInstantiations.empty() || CurContext->isDependentContext();
315 // -- the bodies of non-exported nonspecialized template functions
316 // -- the bodies of inline functions
317 if ((IsInNonspecializedTemplate &&
318 !(ManglingContextDecl && isa<ParmVarDecl>(ManglingContextDecl))) ||
319 isInInlineFunction(CurContext)) {
320 ManglingContextDecl = nullptr;
321 return &Context.getManglingNumberContext(DC);
324 ManglingContextDecl = nullptr;
327 case StaticDataMember:
328 // -- the initializers of nonspecialized static members of template classes
329 if (!IsInNonspecializedTemplate) {
330 ManglingContextDecl = nullptr;
333 // Fall through to get the current context.
336 // -- the in-class initializers of class members
337 case DefaultArgument:
338 // -- default arguments appearing in class definitions
339 return &ExprEvalContexts.back().getMangleNumberingContext(Context);
342 llvm_unreachable("unexpected context");
345 MangleNumberingContext &
346 Sema::ExpressionEvaluationContextRecord::getMangleNumberingContext(
348 assert(ManglingContextDecl && "Need to have a context declaration");
349 if (!MangleNumbering)
350 MangleNumbering = Ctx.createMangleNumberingContext();
351 return *MangleNumbering;
354 CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
355 SourceRange IntroducerRange,
356 TypeSourceInfo *MethodTypeInfo,
357 SourceLocation EndLoc,
358 ArrayRef<ParmVarDecl *> Params) {
359 QualType MethodType = MethodTypeInfo->getType();
360 TemplateParameterList *TemplateParams =
361 getGenericLambdaTemplateParameterList(getCurLambda(), *this);
362 // If a lambda appears in a dependent context or is a generic lambda (has
363 // template parameters) and has an 'auto' return type, deduce it to a
365 if (Class->isDependentContext() || TemplateParams) {
366 const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
367 QualType Result = FPT->getReturnType();
368 if (Result->isUndeducedType()) {
369 Result = SubstAutoType(Result, Context.DependentTy);
370 MethodType = Context.getFunctionType(Result, FPT->getParamTypes(),
371 FPT->getExtProtoInfo());
375 // C++11 [expr.prim.lambda]p5:
376 // The closure type for a lambda-expression has a public inline function
377 // call operator (13.5.4) whose parameters and return type are described by
378 // the lambda-expression's parameter-declaration-clause and
379 // trailing-return-type respectively.
380 DeclarationName MethodName
381 = Context.DeclarationNames.getCXXOperatorName(OO_Call);
382 DeclarationNameLoc MethodNameLoc;
383 MethodNameLoc.CXXOperatorName.BeginOpNameLoc
384 = IntroducerRange.getBegin().getRawEncoding();
385 MethodNameLoc.CXXOperatorName.EndOpNameLoc
386 = IntroducerRange.getEnd().getRawEncoding();
387 CXXMethodDecl *Method
388 = CXXMethodDecl::Create(Context, Class, EndLoc,
389 DeclarationNameInfo(MethodName,
390 IntroducerRange.getBegin(),
392 MethodType, MethodTypeInfo,
395 /*isConstExpr=*/false,
397 Method->setAccess(AS_public);
399 // Temporarily set the lexical declaration context to the current
400 // context, so that the Scope stack matches the lexical nesting.
401 Method->setLexicalDeclContext(CurContext);
402 // Create a function template if we have a template parameter list
403 FunctionTemplateDecl *const TemplateMethod = TemplateParams ?
404 FunctionTemplateDecl::Create(Context, Class,
405 Method->getLocation(), MethodName,
408 if (TemplateMethod) {
409 TemplateMethod->setLexicalDeclContext(CurContext);
410 TemplateMethod->setAccess(AS_public);
411 Method->setDescribedFunctionTemplate(TemplateMethod);
415 if (!Params.empty()) {
416 Method->setParams(Params);
417 CheckParmsForFunctionDef(const_cast<ParmVarDecl **>(Params.begin()),
418 const_cast<ParmVarDecl **>(Params.end()),
419 /*CheckParameterNames=*/false);
421 for (auto P : Method->params())
422 P->setOwningFunction(Method);
425 Decl *ManglingContextDecl;
426 if (MangleNumberingContext *MCtx =
427 getCurrentMangleNumberContext(Class->getDeclContext(),
428 ManglingContextDecl)) {
429 unsigned ManglingNumber = MCtx->getManglingNumber(Method);
430 Class->setLambdaMangling(ManglingNumber, ManglingContextDecl);
436 void Sema::buildLambdaScope(LambdaScopeInfo *LSI,
437 CXXMethodDecl *CallOperator,
438 SourceRange IntroducerRange,
439 LambdaCaptureDefault CaptureDefault,
440 SourceLocation CaptureDefaultLoc,
442 bool ExplicitResultType,
444 LSI->CallOperator = CallOperator;
445 CXXRecordDecl *LambdaClass = CallOperator->getParent();
446 LSI->Lambda = LambdaClass;
447 if (CaptureDefault == LCD_ByCopy)
448 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
449 else if (CaptureDefault == LCD_ByRef)
450 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
451 LSI->CaptureDefaultLoc = CaptureDefaultLoc;
452 LSI->IntroducerRange = IntroducerRange;
453 LSI->ExplicitParams = ExplicitParams;
454 LSI->Mutable = Mutable;
456 if (ExplicitResultType) {
457 LSI->ReturnType = CallOperator->getReturnType();
459 if (!LSI->ReturnType->isDependentType() &&
460 !LSI->ReturnType->isVoidType()) {
461 if (RequireCompleteType(CallOperator->getLocStart(), LSI->ReturnType,
462 diag::err_lambda_incomplete_result)) {
467 LSI->HasImplicitReturnType = true;
471 void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
472 LSI->finishedExplicitCaptures();
475 void Sema::addLambdaParameters(CXXMethodDecl *CallOperator, Scope *CurScope) {
476 // Introduce our parameters into the function scope
477 for (unsigned p = 0, NumParams = CallOperator->getNumParams();
478 p < NumParams; ++p) {
479 ParmVarDecl *Param = CallOperator->getParamDecl(p);
481 // If this has an identifier, add it to the scope stack.
482 if (CurScope && Param->getIdentifier()) {
483 CheckShadow(CurScope, Param);
485 PushOnScopeChains(Param, CurScope);
490 /// If this expression is an enumerator-like expression of some type
491 /// T, return the type T; otherwise, return null.
493 /// Pointer comparisons on the result here should always work because
494 /// it's derived from either the parent of an EnumConstantDecl
495 /// (i.e. the definition) or the declaration returned by
496 /// EnumType::getDecl() (i.e. the definition).
497 static EnumDecl *findEnumForBlockReturn(Expr *E) {
498 // An expression is an enumerator-like expression of type T if,
499 // ignoring parens and parens-like expressions:
500 E = E->IgnoreParens();
502 // - it is an enumerator whose enum type is T or
503 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
504 if (EnumConstantDecl *D
505 = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
506 return cast<EnumDecl>(D->getDeclContext());
511 // - it is a comma expression whose RHS is an enumerator-like
512 // expression of type T or
513 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
514 if (BO->getOpcode() == BO_Comma)
515 return findEnumForBlockReturn(BO->getRHS());
519 // - it is a statement-expression whose value expression is an
520 // enumerator-like expression of type T or
521 if (StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
522 if (Expr *last = dyn_cast_or_null<Expr>(SE->getSubStmt()->body_back()))
523 return findEnumForBlockReturn(last);
527 // - it is a ternary conditional operator (not the GNU ?:
528 // extension) whose second and third operands are
529 // enumerator-like expressions of type T or
530 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
531 if (EnumDecl *ED = findEnumForBlockReturn(CO->getTrueExpr()))
532 if (ED == findEnumForBlockReturn(CO->getFalseExpr()))
538 // - it is an implicit integral conversion applied to an
539 // enumerator-like expression of type T or
540 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
541 // We can sometimes see integral conversions in valid
542 // enumerator-like expressions.
543 if (ICE->getCastKind() == CK_IntegralCast)
544 return findEnumForBlockReturn(ICE->getSubExpr());
546 // Otherwise, just rely on the type.
549 // - it is an expression of that formal enum type.
550 if (const EnumType *ET = E->getType()->getAs<EnumType>()) {
551 return ET->getDecl();
558 /// Attempt to find a type T for which the returned expression of the
559 /// given statement is an enumerator-like expression of that type.
560 static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
561 if (Expr *retValue = ret->getRetValue())
562 return findEnumForBlockReturn(retValue);
566 /// Attempt to find a common type T for which all of the returned
567 /// expressions in a block are enumerator-like expressions of that
569 static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
570 ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
572 // Try to find one for the first return.
573 EnumDecl *ED = findEnumForBlockReturn(*i);
574 if (!ED) return nullptr;
576 // Check that the rest of the returns have the same enum.
577 for (++i; i != e; ++i) {
578 if (findEnumForBlockReturn(*i) != ED)
582 // Never infer an anonymous enum type.
583 if (!ED->hasNameForLinkage()) return nullptr;
588 /// Adjust the given return statements so that they formally return
589 /// the given type. It should require, at most, an IntegralCast.
590 static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
591 QualType returnType) {
592 for (ArrayRef<ReturnStmt*>::iterator
593 i = returns.begin(), e = returns.end(); i != e; ++i) {
594 ReturnStmt *ret = *i;
595 Expr *retValue = ret->getRetValue();
596 if (S.Context.hasSameType(retValue->getType(), returnType))
599 // Right now we only support integral fixup casts.
600 assert(returnType->isIntegralOrUnscopedEnumerationType());
601 assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
603 ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(retValue);
605 Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
606 E = ImplicitCastExpr::Create(S.Context, returnType, CK_IntegralCast,
607 E, /*base path*/ nullptr, VK_RValue);
609 cleanups->setSubExpr(E);
616 void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
617 assert(CSI.HasImplicitReturnType);
618 // If it was ever a placeholder, it had to been deduced to DependentTy.
619 assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
621 // C++ core issue 975:
622 // If a lambda-expression does not include a trailing-return-type,
623 // it is as if the trailing-return-type denotes the following type:
624 // - if there are no return statements in the compound-statement,
625 // or all return statements return either an expression of type
626 // void or no expression or braced-init-list, the type void;
627 // - otherwise, if all return statements return an expression
628 // and the types of the returned expressions after
629 // lvalue-to-rvalue conversion (4.1 [conv.lval]),
630 // array-to-pointer conversion (4.2 [conv.array]), and
631 // function-to-pointer conversion (4.3 [conv.func]) are the
632 // same, that common type;
633 // - otherwise, the program is ill-formed.
635 // C++ core issue 1048 additionally removes top-level cv-qualifiers
636 // from the types of returned expressions to match the C++14 auto
639 // In addition, in blocks in non-C++ modes, if all of the return
640 // statements are enumerator-like expressions of some type T, where
641 // T has a name for linkage, then we infer the return type of the
642 // block to be that type.
644 // First case: no return statements, implicit void return type.
645 ASTContext &Ctx = getASTContext();
646 if (CSI.Returns.empty()) {
647 // It's possible there were simply no /valid/ return statements.
648 // In this case, the first one we found may have at least given us a type.
649 if (CSI.ReturnType.isNull())
650 CSI.ReturnType = Ctx.VoidTy;
654 // Second case: at least one return statement has dependent type.
655 // Delay type checking until instantiation.
656 assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
657 if (CSI.ReturnType->isDependentType())
660 // Try to apply the enum-fuzz rule.
661 if (!getLangOpts().CPlusPlus) {
662 assert(isa<BlockScopeInfo>(CSI));
663 const EnumDecl *ED = findCommonEnumForBlockReturns(CSI.Returns);
665 CSI.ReturnType = Context.getTypeDeclType(ED);
666 adjustBlockReturnsToEnum(*this, CSI.Returns, CSI.ReturnType);
671 // Third case: only one return statement. Don't bother doing extra work!
672 SmallVectorImpl<ReturnStmt*>::iterator I = CSI.Returns.begin(),
673 E = CSI.Returns.end();
677 // General case: many return statements.
678 // Check that they all have compatible return types.
680 // We require the return types to strictly match here.
681 // Note that we've already done the required promotions as part of
682 // processing the return statement.
683 for (; I != E; ++I) {
684 const ReturnStmt *RS = *I;
685 const Expr *RetE = RS->getRetValue();
687 QualType ReturnType =
688 (RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
689 if (Context.getCanonicalFunctionResultType(ReturnType) ==
690 Context.getCanonicalFunctionResultType(CSI.ReturnType))
693 // FIXME: This is a poor diagnostic for ReturnStmts without expressions.
694 // TODO: It's possible that the *first* return is the divergent one.
695 Diag(RS->getLocStart(),
696 diag::err_typecheck_missing_return_type_incompatible)
697 << ReturnType << CSI.ReturnType
698 << isa<LambdaScopeInfo>(CSI);
699 // Continue iterating so that we keep emitting diagnostics.
703 QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
708 // Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
710 QualType DeductType = Context.getAutoDeductType();
712 TLB.pushTypeSpec(DeductType).setNameLoc(Loc);
714 DeductType = BuildReferenceType(DeductType, true, Loc, Id);
715 assert(!DeductType.isNull() && "can't build reference to auto");
716 TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
718 TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
720 // Deduce the type of the init capture.
721 QualType DeducedType = deduceVarTypeFromInitializer(
722 /*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
723 SourceRange(Loc, Loc), IsDirectInit, Init);
724 if (DeducedType.isNull())
727 // Are we a non-list direct initialization?
728 ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
730 // Perform initialization analysis and ensure any implicit conversions
731 // (such as lvalue-to-rvalue) are enforced.
732 InitializedEntity Entity =
733 InitializedEntity::InitializeLambdaCapture(Id, DeducedType, Loc);
734 InitializationKind Kind =
736 ? (CXXDirectInit ? InitializationKind::CreateDirect(
737 Loc, Init->getLocStart(), Init->getLocEnd())
738 : InitializationKind::CreateDirectList(Loc))
739 : InitializationKind::CreateCopy(Loc, Init->getLocStart());
741 MultiExprArg Args = Init;
744 MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
746 InitializationSequence InitSeq(*this, Entity, Kind, Args);
747 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
749 if (Result.isInvalid())
751 Init = Result.getAs<Expr>();
753 // The init-capture initialization is a full-expression that must be
754 // processed as one before we enter the declcontext of the lambda's
756 Result = ActOnFinishFullExpr(Init, Loc, /*DiscardedValue*/ false,
757 /*IsConstexpr*/ false,
758 /*IsLambdaInitCaptureInitalizer*/ true);
759 if (Result.isInvalid())
762 Init = Result.getAs<Expr>();
766 VarDecl *Sema::createLambdaInitCaptureVarDecl(SourceLocation Loc,
767 QualType InitCaptureType,
769 unsigned InitStyle, Expr *Init) {
770 TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType,
772 // Create a dummy variable representing the init-capture. This is not actually
773 // used as a variable, and only exists as a way to name and refer to the
775 // FIXME: Pass in separate source locations for '&' and identifier.
776 VarDecl *NewVD = VarDecl::Create(Context, CurContext, Loc,
777 Loc, Id, InitCaptureType, TSI, SC_Auto);
778 NewVD->setInitCapture(true);
779 NewVD->setReferenced(true);
780 // FIXME: Pass in a VarDecl::InitializationStyle.
781 NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
782 NewVD->markUsed(Context);
783 NewVD->setInit(Init);
787 FieldDecl *Sema::buildInitCaptureField(LambdaScopeInfo *LSI, VarDecl *Var) {
788 FieldDecl *Field = FieldDecl::Create(
789 Context, LSI->Lambda, Var->getLocation(), Var->getLocation(),
790 nullptr, Var->getType(), Var->getTypeSourceInfo(), nullptr, false,
792 Field->setImplicit(true);
793 Field->setAccess(AS_private);
794 LSI->Lambda->addDecl(Field);
796 LSI->addCapture(Var, /*isBlock*/false, Var->getType()->isReferenceType(),
797 /*isNested*/false, Var->getLocation(), SourceLocation(),
798 Var->getType(), Var->getInit());
802 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
803 Declarator &ParamInfo,
805 // Determine if we're within a context where we know that the lambda will
806 // be dependent, because there are template parameters in scope.
807 bool KnownDependent = false;
808 LambdaScopeInfo *const LSI = getCurLambda();
809 assert(LSI && "LambdaScopeInfo should be on stack!");
810 TemplateParameterList *TemplateParams =
811 getGenericLambdaTemplateParameterList(LSI, *this);
813 if (Scope *TmplScope = CurScope->getTemplateParamParent()) {
814 // Since we have our own TemplateParams, so check if an outer scope
815 // has template params, only then are we in a dependent scope.
816 if (TemplateParams) {
817 TmplScope = TmplScope->getParent();
818 TmplScope = TmplScope ? TmplScope->getTemplateParamParent() : nullptr;
820 if (TmplScope && !TmplScope->decl_empty())
821 KnownDependent = true;
823 // Determine the signature of the call operator.
824 TypeSourceInfo *MethodTyInfo;
825 bool ExplicitParams = true;
826 bool ExplicitResultType = true;
827 bool ContainsUnexpandedParameterPack = false;
828 SourceLocation EndLoc;
829 SmallVector<ParmVarDecl *, 8> Params;
830 if (ParamInfo.getNumTypeObjects() == 0) {
831 // C++11 [expr.prim.lambda]p4:
832 // If a lambda-expression does not include a lambda-declarator, it is as
833 // if the lambda-declarator were ().
834 FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(
835 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
836 EPI.HasTrailingReturn = true;
837 EPI.TypeQuals |= DeclSpec::TQ_const;
838 // C++1y [expr.prim.lambda]:
839 // The lambda return type is 'auto', which is replaced by the
840 // trailing-return type if provided and/or deduced from 'return'
842 // We don't do this before C++1y, because we don't support deduced return
844 QualType DefaultTypeForNoTrailingReturn =
845 getLangOpts().CPlusPlus14 ? Context.getAutoDeductType()
846 : Context.DependentTy;
848 Context.getFunctionType(DefaultTypeForNoTrailingReturn, None, EPI);
849 MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy);
850 ExplicitParams = false;
851 ExplicitResultType = false;
852 EndLoc = Intro.Range.getEnd();
854 assert(ParamInfo.isFunctionDeclarator() &&
855 "lambda-declarator is a function");
856 DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
858 // C++11 [expr.prim.lambda]p5:
859 // This function call operator is declared const (9.3.1) if and only if
860 // the lambda-expression's parameter-declaration-clause is not followed
861 // by mutable. It is neither virtual nor declared volatile. [...]
862 if (!FTI.hasMutableQualifier())
863 FTI.TypeQuals |= DeclSpec::TQ_const;
865 MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope);
866 assert(MethodTyInfo && "no type from lambda-declarator");
867 EndLoc = ParamInfo.getSourceRange().getEnd();
869 ExplicitResultType = FTI.hasTrailingReturnType();
871 if (FTIHasNonVoidParameters(FTI)) {
872 Params.reserve(FTI.NumParams);
873 for (unsigned i = 0, e = FTI.NumParams; i != e; ++i)
874 Params.push_back(cast<ParmVarDecl>(FTI.Params[i].Param));
877 // Check for unexpanded parameter packs in the method type.
878 if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
879 ContainsUnexpandedParameterPack = true;
882 CXXRecordDecl *Class = createLambdaClosureType(Intro.Range, MethodTyInfo,
883 KnownDependent, Intro.Default);
885 CXXMethodDecl *Method = startLambdaDefinition(Class, Intro.Range,
886 MethodTyInfo, EndLoc, Params);
888 CheckCXXDefaultArguments(Method);
890 // Attributes on the lambda apply to the method.
891 ProcessDeclAttributes(CurScope, Method, ParamInfo);
893 // Introduce the function call operator as the current declaration context.
894 PushDeclContext(CurScope, Method);
896 // Build the lambda scope.
897 buildLambdaScope(LSI, Method, Intro.Range, Intro.Default, Intro.DefaultLoc,
898 ExplicitParams, ExplicitResultType, !Method->isConst());
900 // C++11 [expr.prim.lambda]p9:
901 // A lambda-expression whose smallest enclosing scope is a block scope is a
902 // local lambda expression; any other lambda expression shall not have a
903 // capture-default or simple-capture in its lambda-introducer.
905 // For simple-captures, this is covered by the check below that any named
906 // entity is a variable that can be captured.
908 // For DR1632, we also allow a capture-default in any context where we can
909 // odr-use 'this' (in particular, in a default initializer for a non-static
911 if (Intro.Default != LCD_None && !Class->getParent()->isFunctionOrMethod() &&
912 (getCurrentThisType().isNull() ||
913 CheckCXXThisCapture(SourceLocation(), /*Explicit*/true,
914 /*BuildAndDiagnose*/false)))
915 Diag(Intro.DefaultLoc, diag::err_capture_default_non_local);
917 // Distinct capture names, for diagnostics.
918 llvm::SmallSet<IdentifierInfo*, 8> CaptureNames;
920 // Handle explicit captures.
921 SourceLocation PrevCaptureLoc
922 = Intro.Default == LCD_None? Intro.Range.getBegin() : Intro.DefaultLoc;
923 for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
924 PrevCaptureLoc = C->Loc, ++C) {
925 if (C->Kind == LCK_This) {
926 // C++11 [expr.prim.lambda]p8:
927 // An identifier or this shall not appear more than once in a
929 if (LSI->isCXXThisCaptured()) {
930 Diag(C->Loc, diag::err_capture_more_than_once)
931 << "'this'" << SourceRange(LSI->getCXXThisCapture().getLocation())
932 << FixItHint::CreateRemoval(
933 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
937 // C++11 [expr.prim.lambda]p8:
938 // If a lambda-capture includes a capture-default that is =, the
939 // lambda-capture shall not contain this [...].
940 if (Intro.Default == LCD_ByCopy) {
941 Diag(C->Loc, diag::err_this_capture_with_copy_default)
942 << FixItHint::CreateRemoval(
943 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
947 // C++11 [expr.prim.lambda]p12:
948 // If this is captured by a local lambda expression, its nearest
949 // enclosing function shall be a non-static member function.
950 QualType ThisCaptureType = getCurrentThisType();
951 if (ThisCaptureType.isNull()) {
952 Diag(C->Loc, diag::err_this_capture) << true;
956 CheckCXXThisCapture(C->Loc, /*Explicit=*/true);
960 assert(C->Id && "missing identifier for capture");
962 if (C->Init.isInvalid())
965 VarDecl *Var = nullptr;
966 if (C->Init.isUsable()) {
967 Diag(C->Loc, getLangOpts().CPlusPlus14
968 ? diag::warn_cxx11_compat_init_capture
969 : diag::ext_init_capture);
971 if (C->Init.get()->containsUnexpandedParameterPack())
972 ContainsUnexpandedParameterPack = true;
973 // If the initializer expression is usable, but the InitCaptureType
974 // is not, then an error has occurred - so ignore the capture for now.
975 // for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
976 // FIXME: we should create the init capture variable and mark it invalid
978 if (C->InitCaptureType.get().isNull())
982 switch (C->InitKind) {
983 case LambdaCaptureInitKind::NoInit:
984 llvm_unreachable("not an init-capture?");
985 case LambdaCaptureInitKind::CopyInit:
986 InitStyle = VarDecl::CInit;
988 case LambdaCaptureInitKind::DirectInit:
989 InitStyle = VarDecl::CallInit;
991 case LambdaCaptureInitKind::ListInit:
992 InitStyle = VarDecl::ListInit;
995 Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
996 C->Id, InitStyle, C->Init.get());
997 // C++1y [expr.prim.lambda]p11:
998 // An init-capture behaves as if it declares and explicitly
999 // captures a variable [...] whose declarative region is the
1000 // lambda-expression's compound-statement
1002 PushOnScopeChains(Var, CurScope, false);
1004 assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
1005 "init capture has valid but null init?");
1007 // C++11 [expr.prim.lambda]p8:
1008 // If a lambda-capture includes a capture-default that is &, the
1009 // identifiers in the lambda-capture shall not be preceded by &.
1010 // If a lambda-capture includes a capture-default that is =, [...]
1011 // each identifier it contains shall be preceded by &.
1012 if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
1013 Diag(C->Loc, diag::err_reference_capture_with_reference_default)
1014 << FixItHint::CreateRemoval(
1015 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1017 } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
1018 Diag(C->Loc, diag::err_copy_capture_with_copy_default)
1019 << FixItHint::CreateRemoval(
1020 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1024 // C++11 [expr.prim.lambda]p10:
1025 // The identifiers in a capture-list are looked up using the usual
1026 // rules for unqualified name lookup (3.4.1)
1027 DeclarationNameInfo Name(C->Id, C->Loc);
1028 LookupResult R(*this, Name, LookupOrdinaryName);
1029 LookupName(R, CurScope);
1030 if (R.isAmbiguous())
1033 // FIXME: Disable corrections that would add qualification?
1034 CXXScopeSpec ScopeSpec;
1035 if (DiagnoseEmptyLookup(CurScope, ScopeSpec, R,
1036 llvm::make_unique<DeclFilterCCC<VarDecl>>()))
1040 Var = R.getAsSingle<VarDecl>();
1041 if (Var && DiagnoseUseOfDecl(Var, C->Loc))
1045 // C++11 [expr.prim.lambda]p8:
1046 // An identifier or this shall not appear more than once in a
1048 if (!CaptureNames.insert(C->Id).second) {
1049 if (Var && LSI->isCaptured(Var)) {
1050 Diag(C->Loc, diag::err_capture_more_than_once)
1051 << C->Id << SourceRange(LSI->getCapture(Var).getLocation())
1052 << FixItHint::CreateRemoval(
1053 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1055 // Previous capture captured something different (one or both was
1056 // an init-cpature): no fixit.
1057 Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
1061 // C++11 [expr.prim.lambda]p10:
1062 // [...] each such lookup shall find a variable with automatic storage
1063 // duration declared in the reaching scope of the local lambda expression.
1064 // Note that the 'reaching scope' check happens in tryCaptureVariable().
1066 Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id;
1070 // Ignore invalid decls; they'll just confuse the code later.
1071 if (Var->isInvalidDecl())
1074 if (!Var->hasLocalStorage()) {
1075 Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id;
1076 Diag(Var->getLocation(), diag::note_previous_decl) << C->Id;
1080 // C++11 [expr.prim.lambda]p23:
1081 // A capture followed by an ellipsis is a pack expansion (14.5.3).
1082 SourceLocation EllipsisLoc;
1083 if (C->EllipsisLoc.isValid()) {
1084 if (Var->isParameterPack()) {
1085 EllipsisLoc = C->EllipsisLoc;
1087 Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
1088 << SourceRange(C->Loc);
1090 // Just ignore the ellipsis.
1092 } else if (Var->isParameterPack()) {
1093 ContainsUnexpandedParameterPack = true;
1096 if (C->Init.isUsable()) {
1097 buildInitCaptureField(LSI, Var);
1099 TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef :
1100 TryCapture_ExplicitByVal;
1101 tryCaptureVariable(Var, C->Loc, Kind, EllipsisLoc);
1104 finishLambdaExplicitCaptures(LSI);
1106 LSI->ContainsUnexpandedParameterPack = ContainsUnexpandedParameterPack;
1108 // Add lambda parameters into scope.
1109 addLambdaParameters(Method, CurScope);
1111 // Enter a new evaluation context to insulate the lambda from any
1112 // cleanups from the enclosing full-expression.
1113 PushExpressionEvaluationContext(PotentiallyEvaluated);
1116 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
1117 bool IsInstantiation) {
1118 LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
1120 // Leave the expression-evaluation context.
1121 DiscardCleanupsInEvaluationContext();
1122 PopExpressionEvaluationContext();
1124 // Leave the context of the lambda.
1125 if (!IsInstantiation)
1128 // Finalize the lambda.
1129 CXXRecordDecl *Class = LSI->Lambda;
1130 Class->setInvalidDecl();
1131 SmallVector<Decl*, 4> Fields(Class->fields());
1132 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1133 SourceLocation(), nullptr);
1134 CheckCompletedCXXClass(Class);
1136 PopFunctionScopeInfo();
1139 /// \brief Add a lambda's conversion to function pointer, as described in
1140 /// C++11 [expr.prim.lambda]p6.
1141 static void addFunctionPointerConversion(Sema &S,
1142 SourceRange IntroducerRange,
1143 CXXRecordDecl *Class,
1144 CXXMethodDecl *CallOperator) {
1145 // This conversion is explicitly disabled if the lambda's function has
1146 // pass_object_size attributes on any of its parameters.
1147 if (std::any_of(CallOperator->param_begin(), CallOperator->param_end(),
1148 std::mem_fn(&ParmVarDecl::hasAttr<PassObjectSizeAttr>)))
1151 // Add the conversion to function pointer.
1152 const FunctionProtoType *CallOpProto =
1153 CallOperator->getType()->getAs<FunctionProtoType>();
1154 const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
1155 CallOpProto->getExtProtoInfo();
1156 QualType PtrToFunctionTy;
1157 QualType InvokerFunctionTy;
1159 FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
1160 CallingConv CC = S.Context.getDefaultCallingConvention(
1161 CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
1162 InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(CC);
1163 InvokerExtInfo.TypeQuals = 0;
1164 assert(InvokerExtInfo.RefQualifier == RQ_None &&
1165 "Lambda's call operator should not have a reference qualifier");
1167 S.Context.getFunctionType(CallOpProto->getReturnType(),
1168 CallOpProto->getParamTypes(), InvokerExtInfo);
1169 PtrToFunctionTy = S.Context.getPointerType(InvokerFunctionTy);
1172 // Create the type of the conversion function.
1173 FunctionProtoType::ExtProtoInfo ConvExtInfo(
1174 S.Context.getDefaultCallingConvention(
1175 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1176 // The conversion function is always const.
1177 ConvExtInfo.TypeQuals = Qualifiers::Const;
1179 S.Context.getFunctionType(PtrToFunctionTy, None, ConvExtInfo);
1181 SourceLocation Loc = IntroducerRange.getBegin();
1182 DeclarationName ConversionName
1183 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1184 S.Context.getCanonicalType(PtrToFunctionTy));
1185 DeclarationNameLoc ConvNameLoc;
1186 // Construct a TypeSourceInfo for the conversion function, and wire
1187 // all the parameters appropriately for the FunctionProtoTypeLoc
1188 // so that everything works during transformation/instantiation of
1190 // The main reason for wiring up the parameters of the conversion
1191 // function with that of the call operator is so that constructs
1192 // like the following work:
1193 // auto L = [](auto b) { <-- 1
1194 // return [](auto a) -> decltype(a) { <-- 2
1198 // int (*fp)(int) = L(5);
1199 // Because the trailing return type can contain DeclRefExprs that refer
1200 // to the original call operator's variables, we hijack the call
1201 // operators ParmVarDecls below.
1202 TypeSourceInfo *ConvNamePtrToFunctionTSI =
1203 S.Context.getTrivialTypeSourceInfo(PtrToFunctionTy, Loc);
1204 ConvNameLoc.NamedType.TInfo = ConvNamePtrToFunctionTSI;
1206 // The conversion function is a conversion to a pointer-to-function.
1207 TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(ConvTy, Loc);
1208 FunctionProtoTypeLoc ConvTL =
1209 ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
1210 // Get the result of the conversion function which is a pointer-to-function.
1211 PointerTypeLoc PtrToFunctionTL =
1212 ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
1213 // Do the same for the TypeSourceInfo that is used to name the conversion
1215 PointerTypeLoc ConvNamePtrToFunctionTL =
1216 ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
1218 // Get the underlying function types that the conversion function will
1219 // be converting to (should match the type of the call operator).
1220 FunctionProtoTypeLoc CallOpConvTL =
1221 PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1222 FunctionProtoTypeLoc CallOpConvNameTL =
1223 ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1225 // Wire up the FunctionProtoTypeLocs with the call operator's parameters.
1226 // These parameter's are essentially used to transform the name and
1227 // the type of the conversion operator. By using the same parameters
1228 // as the call operator's we don't have to fix any back references that
1229 // the trailing return type of the call operator's uses (such as
1230 // decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
1231 // - we can simply use the return type of the call operator, and
1232 // everything should work.
1233 SmallVector<ParmVarDecl *, 4> InvokerParams;
1234 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1235 ParmVarDecl *From = CallOperator->getParamDecl(I);
1237 InvokerParams.push_back(ParmVarDecl::Create(S.Context,
1238 // Temporarily add to the TU. This is set to the invoker below.
1239 S.Context.getTranslationUnitDecl(),
1240 From->getLocStart(),
1241 From->getLocation(),
1242 From->getIdentifier(),
1244 From->getTypeSourceInfo(),
1245 From->getStorageClass(),
1246 /*DefaultArg=*/nullptr));
1247 CallOpConvTL.setParam(I, From);
1248 CallOpConvNameTL.setParam(I, From);
1251 CXXConversionDecl *Conversion
1252 = CXXConversionDecl::Create(S.Context, Class, Loc,
1253 DeclarationNameInfo(ConversionName,
1257 /*isInline=*/true, /*isExplicit=*/false,
1258 /*isConstexpr=*/false,
1259 CallOperator->getBody()->getLocEnd());
1260 Conversion->setAccess(AS_public);
1261 Conversion->setImplicit(true);
1263 if (Class->isGenericLambda()) {
1264 // Create a template version of the conversion operator, using the template
1265 // parameter list of the function call operator.
1266 FunctionTemplateDecl *TemplateCallOperator =
1267 CallOperator->getDescribedFunctionTemplate();
1268 FunctionTemplateDecl *ConversionTemplate =
1269 FunctionTemplateDecl::Create(S.Context, Class,
1270 Loc, ConversionName,
1271 TemplateCallOperator->getTemplateParameters(),
1273 ConversionTemplate->setAccess(AS_public);
1274 ConversionTemplate->setImplicit(true);
1275 Conversion->setDescribedFunctionTemplate(ConversionTemplate);
1276 Class->addDecl(ConversionTemplate);
1278 Class->addDecl(Conversion);
1279 // Add a non-static member function that will be the result of
1280 // the conversion with a certain unique ID.
1281 DeclarationName InvokerName = &S.Context.Idents.get(
1282 getLambdaStaticInvokerName());
1283 // FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
1284 // we should get a prebuilt TrivialTypeSourceInfo from Context
1285 // using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
1286 // then rewire the parameters accordingly, by hoisting up the InvokeParams
1287 // loop below and then use its Params to set Invoke->setParams(...) below.
1288 // This would avoid the 'const' qualifier of the calloperator from
1289 // contaminating the type of the invoker, which is currently adjusted
1290 // in SemaTemplateDeduction.cpp:DeduceTemplateArguments. Fixing the
1291 // trailing return type of the invoker would require a visitor to rebuild
1292 // the trailing return type and adjusting all back DeclRefExpr's to refer
1293 // to the new static invoker parameters - not the call operator's.
1294 CXXMethodDecl *Invoke
1295 = CXXMethodDecl::Create(S.Context, Class, Loc,
1296 DeclarationNameInfo(InvokerName, Loc),
1298 CallOperator->getTypeSourceInfo(),
1299 SC_Static, /*IsInline=*/true,
1300 /*IsConstexpr=*/false,
1301 CallOperator->getBody()->getLocEnd());
1302 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
1303 InvokerParams[I]->setOwningFunction(Invoke);
1304 Invoke->setParams(InvokerParams);
1305 Invoke->setAccess(AS_private);
1306 Invoke->setImplicit(true);
1307 if (Class->isGenericLambda()) {
1308 FunctionTemplateDecl *TemplateCallOperator =
1309 CallOperator->getDescribedFunctionTemplate();
1310 FunctionTemplateDecl *StaticInvokerTemplate = FunctionTemplateDecl::Create(
1311 S.Context, Class, Loc, InvokerName,
1312 TemplateCallOperator->getTemplateParameters(),
1314 StaticInvokerTemplate->setAccess(AS_private);
1315 StaticInvokerTemplate->setImplicit(true);
1316 Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
1317 Class->addDecl(StaticInvokerTemplate);
1319 Class->addDecl(Invoke);
1322 /// \brief Add a lambda's conversion to block pointer.
1323 static void addBlockPointerConversion(Sema &S,
1324 SourceRange IntroducerRange,
1325 CXXRecordDecl *Class,
1326 CXXMethodDecl *CallOperator) {
1327 const FunctionProtoType *Proto =
1328 CallOperator->getType()->getAs<FunctionProtoType>();
1330 // The function type inside the block pointer type is the same as the call
1331 // operator with some tweaks. The calling convention is the default free
1332 // function convention, and the type qualifications are lost.
1333 FunctionProtoType::ExtProtoInfo BlockEPI = Proto->getExtProtoInfo();
1335 BlockEPI.ExtInfo.withCallingConv(S.Context.getDefaultCallingConvention(
1336 Proto->isVariadic(), /*IsCXXMethod=*/false));
1337 BlockEPI.TypeQuals = 0;
1338 QualType FunctionTy = S.Context.getFunctionType(
1339 Proto->getReturnType(), Proto->getParamTypes(), BlockEPI);
1340 QualType BlockPtrTy = S.Context.getBlockPointerType(FunctionTy);
1342 FunctionProtoType::ExtProtoInfo ConversionEPI(
1343 S.Context.getDefaultCallingConvention(
1344 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1345 ConversionEPI.TypeQuals = Qualifiers::Const;
1346 QualType ConvTy = S.Context.getFunctionType(BlockPtrTy, None, ConversionEPI);
1348 SourceLocation Loc = IntroducerRange.getBegin();
1349 DeclarationName Name
1350 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1351 S.Context.getCanonicalType(BlockPtrTy));
1352 DeclarationNameLoc NameLoc;
1353 NameLoc.NamedType.TInfo = S.Context.getTrivialTypeSourceInfo(BlockPtrTy, Loc);
1354 CXXConversionDecl *Conversion
1355 = CXXConversionDecl::Create(S.Context, Class, Loc,
1356 DeclarationNameInfo(Name, Loc, NameLoc),
1358 S.Context.getTrivialTypeSourceInfo(ConvTy, Loc),
1359 /*isInline=*/true, /*isExplicit=*/false,
1360 /*isConstexpr=*/false,
1361 CallOperator->getBody()->getLocEnd());
1362 Conversion->setAccess(AS_public);
1363 Conversion->setImplicit(true);
1364 Class->addDecl(Conversion);
1367 static ExprResult performLambdaVarCaptureInitialization(
1368 Sema &S, LambdaScopeInfo::Capture &Capture,
1370 SmallVectorImpl<VarDecl *> &ArrayIndexVars,
1371 SmallVectorImpl<unsigned> &ArrayIndexStarts) {
1372 assert(Capture.isVariableCapture() && "not a variable capture");
1374 auto *Var = Capture.getVariable();
1375 SourceLocation Loc = Capture.getLocation();
1377 // C++11 [expr.prim.lambda]p21:
1378 // When the lambda-expression is evaluated, the entities that
1379 // are captured by copy are used to direct-initialize each
1380 // corresponding non-static data member of the resulting closure
1381 // object. (For array members, the array elements are
1382 // direct-initialized in increasing subscript order.) These
1383 // initializations are performed in the (unspecified) order in
1384 // which the non-static data members are declared.
1386 // C++ [expr.prim.lambda]p12:
1387 // An entity captured by a lambda-expression is odr-used (3.2) in
1388 // the scope containing the lambda-expression.
1389 ExprResult RefResult = S.BuildDeclarationNameExpr(
1390 CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
1391 if (RefResult.isInvalid())
1393 Expr *Ref = RefResult.get();
1395 QualType FieldType = Field->getType();
1397 // When the variable has array type, create index variables for each
1398 // dimension of the array. We use these index variables to subscript
1399 // the source array, and other clients (e.g., CodeGen) will perform
1400 // the necessary iteration with these index variables.
1402 // FIXME: This is dumb. Add a proper AST representation for array
1403 // copy-construction and use it here.
1404 SmallVector<VarDecl *, 4> IndexVariables;
1405 QualType BaseType = FieldType;
1406 QualType SizeType = S.Context.getSizeType();
1407 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1408 while (const ConstantArrayType *Array
1409 = S.Context.getAsConstantArrayType(BaseType)) {
1410 // Create the iteration variable for this array index.
1411 IdentifierInfo *IterationVarName = nullptr;
1414 llvm::raw_svector_ostream OS(Str);
1415 OS << "__i" << IndexVariables.size();
1416 IterationVarName = &S.Context.Idents.get(OS.str());
1418 VarDecl *IterationVar = VarDecl::Create(
1419 S.Context, S.CurContext, Loc, Loc, IterationVarName, SizeType,
1420 S.Context.getTrivialTypeSourceInfo(SizeType, Loc), SC_None);
1421 IterationVar->setImplicit();
1422 IndexVariables.push_back(IterationVar);
1423 ArrayIndexVars.push_back(IterationVar);
1425 // Create a reference to the iteration variable.
1426 ExprResult IterationVarRef =
1427 S.BuildDeclRefExpr(IterationVar, SizeType, VK_LValue, Loc);
1428 assert(!IterationVarRef.isInvalid() &&
1429 "Reference to invented variable cannot fail!");
1430 IterationVarRef = S.DefaultLvalueConversion(IterationVarRef.get());
1431 assert(!IterationVarRef.isInvalid() &&
1432 "Conversion of invented variable cannot fail!");
1434 // Subscript the array with this iteration variable.
1435 ExprResult Subscript =
1436 S.CreateBuiltinArraySubscriptExpr(Ref, Loc, IterationVarRef.get(), Loc);
1437 if (Subscript.isInvalid())
1440 Ref = Subscript.get();
1441 BaseType = Array->getElementType();
1444 // Construct the entity that we will be initializing. For an array, this
1445 // will be first element in the array, which may require several levels
1446 // of array-subscript entities.
1447 SmallVector<InitializedEntity, 4> Entities;
1448 Entities.reserve(1 + IndexVariables.size());
1449 Entities.push_back(InitializedEntity::InitializeLambdaCapture(
1450 Var->getIdentifier(), FieldType, Loc));
1451 for (unsigned I = 0, N = IndexVariables.size(); I != N; ++I)
1453 InitializedEntity::InitializeElement(S.Context, 0, Entities.back()));
1455 InitializationKind InitKind = InitializationKind::CreateDirect(Loc, Loc, Loc);
1456 InitializationSequence Init(S, Entities.back(), InitKind, Ref);
1457 return Init.Perform(S, Entities.back(), InitKind, Ref);
1460 ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
1462 LambdaScopeInfo LSI = *cast<LambdaScopeInfo>(FunctionScopes.back());
1463 ActOnFinishFunctionBody(LSI.CallOperator, Body);
1464 return BuildLambdaExpr(StartLoc, Body->getLocEnd(), &LSI);
1467 static LambdaCaptureDefault
1468 mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
1470 case CapturingScopeInfo::ImpCap_None:
1472 case CapturingScopeInfo::ImpCap_LambdaByval:
1474 case CapturingScopeInfo::ImpCap_CapturedRegion:
1475 case CapturingScopeInfo::ImpCap_LambdaByref:
1477 case CapturingScopeInfo::ImpCap_Block:
1478 llvm_unreachable("block capture in lambda");
1480 llvm_unreachable("Unknown implicit capture style");
1483 ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
1484 LambdaScopeInfo *LSI) {
1485 // Collect information from the lambda scope.
1486 SmallVector<LambdaCapture, 4> Captures;
1487 SmallVector<Expr *, 4> CaptureInits;
1488 SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
1489 LambdaCaptureDefault CaptureDefault =
1490 mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
1491 CXXRecordDecl *Class;
1492 CXXMethodDecl *CallOperator;
1493 SourceRange IntroducerRange;
1494 bool ExplicitParams;
1495 bool ExplicitResultType;
1496 bool LambdaExprNeedsCleanups;
1497 bool ContainsUnexpandedParameterPack;
1498 SmallVector<VarDecl *, 4> ArrayIndexVars;
1499 SmallVector<unsigned, 4> ArrayIndexStarts;
1501 CallOperator = LSI->CallOperator;
1502 Class = LSI->Lambda;
1503 IntroducerRange = LSI->IntroducerRange;
1504 ExplicitParams = LSI->ExplicitParams;
1505 ExplicitResultType = !LSI->HasImplicitReturnType;
1506 LambdaExprNeedsCleanups = LSI->ExprNeedsCleanups;
1507 ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
1509 CallOperator->setLexicalDeclContext(Class);
1510 Decl *TemplateOrNonTemplateCallOperatorDecl =
1511 CallOperator->getDescribedFunctionTemplate()
1512 ? CallOperator->getDescribedFunctionTemplate()
1513 : cast<Decl>(CallOperator);
1515 TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
1516 Class->addDecl(TemplateOrNonTemplateCallOperatorDecl);
1518 PopExpressionEvaluationContext();
1520 // Translate captures.
1521 auto CurField = Class->field_begin();
1522 for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I, ++CurField) {
1523 LambdaScopeInfo::Capture From = LSI->Captures[I];
1524 assert(!From.isBlockCapture() && "Cannot capture __block variables");
1525 bool IsImplicit = I >= LSI->NumExplicitCaptures;
1527 // Handle 'this' capture.
1528 if (From.isThisCapture()) {
1530 LambdaCapture(From.getLocation(), IsImplicit, LCK_This));
1531 CaptureInits.push_back(new (Context) CXXThisExpr(From.getLocation(),
1532 getCurrentThisType(),
1533 /*isImplicit=*/true));
1534 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1537 if (From.isVLATypeCapture()) {
1539 LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType));
1540 CaptureInits.push_back(nullptr);
1541 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1545 VarDecl *Var = From.getVariable();
1546 LambdaCaptureKind Kind = From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
1547 Captures.push_back(LambdaCapture(From.getLocation(), IsImplicit, Kind,
1548 Var, From.getEllipsisLoc()));
1549 Expr *Init = From.getInitExpr();
1551 auto InitResult = performLambdaVarCaptureInitialization(
1552 *this, From, *CurField, ArrayIndexVars, ArrayIndexStarts);
1553 if (InitResult.isInvalid())
1555 Init = InitResult.get();
1557 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1559 CaptureInits.push_back(Init);
1562 // C++11 [expr.prim.lambda]p6:
1563 // The closure type for a lambda-expression with no lambda-capture
1564 // has a public non-virtual non-explicit const conversion function
1565 // to pointer to function having the same parameter and return
1566 // types as the closure type's function call operator.
1567 if (Captures.empty() && CaptureDefault == LCD_None)
1568 addFunctionPointerConversion(*this, IntroducerRange, Class,
1572 // The closure type for a lambda-expression has a public non-virtual
1573 // non-explicit const conversion function to a block pointer having the
1574 // same parameter and return types as the closure type's function call
1576 // FIXME: Fix generic lambda to block conversions.
1577 if (getLangOpts().Blocks && getLangOpts().ObjC1 &&
1578 !Class->isGenericLambda())
1579 addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
1581 // Finalize the lambda class.
1582 SmallVector<Decl*, 4> Fields(Class->fields());
1583 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1584 SourceLocation(), nullptr);
1585 CheckCompletedCXXClass(Class);
1588 if (LambdaExprNeedsCleanups)
1589 ExprNeedsCleanups = true;
1591 LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange,
1592 CaptureDefault, CaptureDefaultLoc,
1594 ExplicitParams, ExplicitResultType,
1595 CaptureInits, ArrayIndexVars,
1596 ArrayIndexStarts, EndLoc,
1597 ContainsUnexpandedParameterPack);
1599 if (!CurContext->isDependentContext()) {
1600 switch (ExprEvalContexts.back().Context) {
1601 // C++11 [expr.prim.lambda]p2:
1602 // A lambda-expression shall not appear in an unevaluated operand
1605 case UnevaluatedAbstract:
1606 // C++1y [expr.const]p2:
1607 // A conditional-expression e is a core constant expression unless the
1608 // evaluation of e, following the rules of the abstract machine, would
1609 // evaluate [...] a lambda-expression.
1611 // This is technically incorrect, there are some constant evaluated contexts
1612 // where this should be allowed. We should probably fix this when DR1607 is
1613 // ratified, it lays out the exact set of conditions where we shouldn't
1614 // allow a lambda-expression.
1615 case ConstantEvaluated:
1616 // We don't actually diagnose this case immediately, because we
1617 // could be within a context where we might find out later that
1618 // the expression is potentially evaluated (e.g., for typeid).
1619 ExprEvalContexts.back().Lambdas.push_back(Lambda);
1622 case PotentiallyEvaluated:
1623 case PotentiallyEvaluatedIfUsed:
1628 return MaybeBindToTemporary(Lambda);
1631 ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
1632 SourceLocation ConvLocation,
1633 CXXConversionDecl *Conv,
1635 // Make sure that the lambda call operator is marked used.
1636 CXXRecordDecl *Lambda = Conv->getParent();
1637 CXXMethodDecl *CallOperator
1638 = cast<CXXMethodDecl>(
1640 Context.DeclarationNames.getCXXOperatorName(OO_Call)).front());
1641 CallOperator->setReferenced();
1642 CallOperator->markUsed(Context);
1644 ExprResult Init = PerformCopyInitialization(
1645 InitializedEntity::InitializeBlock(ConvLocation,
1648 CurrentLocation, Src);
1649 if (!Init.isInvalid())
1650 Init = ActOnFinishFullExpr(Init.get());
1652 if (Init.isInvalid())
1655 // Create the new block to be returned.
1656 BlockDecl *Block = BlockDecl::Create(Context, CurContext, ConvLocation);
1658 // Set the type information.
1659 Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
1660 Block->setIsVariadic(CallOperator->isVariadic());
1661 Block->setBlockMissingReturnType(false);
1664 SmallVector<ParmVarDecl *, 4> BlockParams;
1665 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1666 ParmVarDecl *From = CallOperator->getParamDecl(I);
1667 BlockParams.push_back(ParmVarDecl::Create(Context, Block,
1668 From->getLocStart(),
1669 From->getLocation(),
1670 From->getIdentifier(),
1672 From->getTypeSourceInfo(),
1673 From->getStorageClass(),
1674 /*DefaultArg=*/nullptr));
1676 Block->setParams(BlockParams);
1678 Block->setIsConversionFromLambda(true);
1680 // Add capture. The capture uses a fake variable, which doesn't correspond
1681 // to any actual memory location. However, the initializer copy-initializes
1682 // the lambda object.
1683 TypeSourceInfo *CapVarTSI =
1684 Context.getTrivialTypeSourceInfo(Src->getType());
1685 VarDecl *CapVar = VarDecl::Create(Context, Block, ConvLocation,
1686 ConvLocation, nullptr,
1687 Src->getType(), CapVarTSI,
1689 BlockDecl::Capture Capture(/*Variable=*/CapVar, /*ByRef=*/false,
1690 /*Nested=*/false, /*Copy=*/Init.get());
1691 Block->setCaptures(Context, Capture, /*CapturesCXXThis=*/false);
1693 // Add a fake function body to the block. IR generation is responsible
1694 // for filling in the actual body, which cannot be expressed as an AST.
1695 Block->setBody(new (Context) CompoundStmt(ConvLocation));
1697 // Create the block literal expression.
1698 Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
1699 ExprCleanupObjects.push_back(Block);
1700 ExprNeedsCleanups = true;