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 QualType MethodType = MethodTypeInfo->getType();
366 TemplateParameterList *TemplateParams =
367 getGenericLambdaTemplateParameterList(getCurLambda(), *this);
368 // If a lambda appears in a dependent context or is a generic lambda (has
369 // template parameters) and has an 'auto' return type, deduce it to a
371 if (Class->isDependentContext() || TemplateParams) {
372 const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
373 QualType Result = FPT->getReturnType();
374 if (Result->isUndeducedType()) {
375 Result = SubstAutoType(Result, Context.DependentTy);
376 MethodType = Context.getFunctionType(Result, FPT->getParamTypes(),
377 FPT->getExtProtoInfo());
381 // C++11 [expr.prim.lambda]p5:
382 // The closure type for a lambda-expression has a public inline function
383 // call operator (13.5.4) whose parameters and return type are described by
384 // the lambda-expression's parameter-declaration-clause and
385 // trailing-return-type respectively.
386 DeclarationName MethodName
387 = Context.DeclarationNames.getCXXOperatorName(OO_Call);
388 DeclarationNameLoc MethodNameLoc;
389 MethodNameLoc.CXXOperatorName.BeginOpNameLoc
390 = IntroducerRange.getBegin().getRawEncoding();
391 MethodNameLoc.CXXOperatorName.EndOpNameLoc
392 = IntroducerRange.getEnd().getRawEncoding();
393 CXXMethodDecl *Method
394 = CXXMethodDecl::Create(Context, Class, EndLoc,
395 DeclarationNameInfo(MethodName,
396 IntroducerRange.getBegin(),
398 MethodType, MethodTypeInfo,
401 /*isConstExpr=*/false,
403 Method->setAccess(AS_public);
405 // Temporarily set the lexical declaration context to the current
406 // context, so that the Scope stack matches the lexical nesting.
407 Method->setLexicalDeclContext(CurContext);
408 // Create a function template if we have a template parameter list
409 FunctionTemplateDecl *const TemplateMethod = TemplateParams ?
410 FunctionTemplateDecl::Create(Context, Class,
411 Method->getLocation(), MethodName,
414 if (TemplateMethod) {
415 TemplateMethod->setLexicalDeclContext(CurContext);
416 TemplateMethod->setAccess(AS_public);
417 Method->setDescribedFunctionTemplate(TemplateMethod);
421 if (!Params.empty()) {
422 Method->setParams(Params);
423 CheckParmsForFunctionDef(Params,
424 /*CheckParameterNames=*/false);
426 for (auto P : Method->parameters())
427 P->setOwningFunction(Method);
430 Decl *ManglingContextDecl;
431 if (MangleNumberingContext *MCtx =
432 getCurrentMangleNumberContext(Class->getDeclContext(),
433 ManglingContextDecl)) {
434 unsigned ManglingNumber = MCtx->getManglingNumber(Method);
435 Class->setLambdaMangling(ManglingNumber, ManglingContextDecl);
441 void Sema::buildLambdaScope(LambdaScopeInfo *LSI,
442 CXXMethodDecl *CallOperator,
443 SourceRange IntroducerRange,
444 LambdaCaptureDefault CaptureDefault,
445 SourceLocation CaptureDefaultLoc,
447 bool ExplicitResultType,
449 LSI->CallOperator = CallOperator;
450 CXXRecordDecl *LambdaClass = CallOperator->getParent();
451 LSI->Lambda = LambdaClass;
452 if (CaptureDefault == LCD_ByCopy)
453 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
454 else if (CaptureDefault == LCD_ByRef)
455 LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
456 LSI->CaptureDefaultLoc = CaptureDefaultLoc;
457 LSI->IntroducerRange = IntroducerRange;
458 LSI->ExplicitParams = ExplicitParams;
459 LSI->Mutable = Mutable;
461 if (ExplicitResultType) {
462 LSI->ReturnType = CallOperator->getReturnType();
464 if (!LSI->ReturnType->isDependentType() &&
465 !LSI->ReturnType->isVoidType()) {
466 if (RequireCompleteType(CallOperator->getLocStart(), LSI->ReturnType,
467 diag::err_lambda_incomplete_result)) {
472 LSI->HasImplicitReturnType = true;
476 void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
477 LSI->finishedExplicitCaptures();
480 void Sema::addLambdaParameters(CXXMethodDecl *CallOperator, Scope *CurScope) {
481 // Introduce our parameters into the function scope
482 for (unsigned p = 0, NumParams = CallOperator->getNumParams();
483 p < NumParams; ++p) {
484 ParmVarDecl *Param = CallOperator->getParamDecl(p);
486 // If this has an identifier, add it to the scope stack.
487 if (CurScope && Param->getIdentifier()) {
488 CheckShadow(CurScope, Param);
490 PushOnScopeChains(Param, CurScope);
495 /// If this expression is an enumerator-like expression of some type
496 /// T, return the type T; otherwise, return null.
498 /// Pointer comparisons on the result here should always work because
499 /// it's derived from either the parent of an EnumConstantDecl
500 /// (i.e. the definition) or the declaration returned by
501 /// EnumType::getDecl() (i.e. the definition).
502 static EnumDecl *findEnumForBlockReturn(Expr *E) {
503 // An expression is an enumerator-like expression of type T if,
504 // ignoring parens and parens-like expressions:
505 E = E->IgnoreParens();
507 // - it is an enumerator whose enum type is T or
508 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
509 if (EnumConstantDecl *D
510 = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
511 return cast<EnumDecl>(D->getDeclContext());
516 // - it is a comma expression whose RHS is an enumerator-like
517 // expression of type T or
518 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
519 if (BO->getOpcode() == BO_Comma)
520 return findEnumForBlockReturn(BO->getRHS());
524 // - it is a statement-expression whose value expression is an
525 // enumerator-like expression of type T or
526 if (StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
527 if (Expr *last = dyn_cast_or_null<Expr>(SE->getSubStmt()->body_back()))
528 return findEnumForBlockReturn(last);
532 // - it is a ternary conditional operator (not the GNU ?:
533 // extension) whose second and third operands are
534 // enumerator-like expressions of type T or
535 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
536 if (EnumDecl *ED = findEnumForBlockReturn(CO->getTrueExpr()))
537 if (ED == findEnumForBlockReturn(CO->getFalseExpr()))
543 // - it is an implicit integral conversion applied to an
544 // enumerator-like expression of type T or
545 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
546 // We can sometimes see integral conversions in valid
547 // enumerator-like expressions.
548 if (ICE->getCastKind() == CK_IntegralCast)
549 return findEnumForBlockReturn(ICE->getSubExpr());
551 // Otherwise, just rely on the type.
554 // - it is an expression of that formal enum type.
555 if (const EnumType *ET = E->getType()->getAs<EnumType>()) {
556 return ET->getDecl();
563 /// Attempt to find a type T for which the returned expression of the
564 /// given statement is an enumerator-like expression of that type.
565 static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
566 if (Expr *retValue = ret->getRetValue())
567 return findEnumForBlockReturn(retValue);
571 /// Attempt to find a common type T for which all of the returned
572 /// expressions in a block are enumerator-like expressions of that
574 static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
575 ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
577 // Try to find one for the first return.
578 EnumDecl *ED = findEnumForBlockReturn(*i);
579 if (!ED) return nullptr;
581 // Check that the rest of the returns have the same enum.
582 for (++i; i != e; ++i) {
583 if (findEnumForBlockReturn(*i) != ED)
587 // Never infer an anonymous enum type.
588 if (!ED->hasNameForLinkage()) return nullptr;
593 /// Adjust the given return statements so that they formally return
594 /// the given type. It should require, at most, an IntegralCast.
595 static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
596 QualType returnType) {
597 for (ArrayRef<ReturnStmt*>::iterator
598 i = returns.begin(), e = returns.end(); i != e; ++i) {
599 ReturnStmt *ret = *i;
600 Expr *retValue = ret->getRetValue();
601 if (S.Context.hasSameType(retValue->getType(), returnType))
604 // Right now we only support integral fixup casts.
605 assert(returnType->isIntegralOrUnscopedEnumerationType());
606 assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
608 ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(retValue);
610 Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
611 E = ImplicitCastExpr::Create(S.Context, returnType, CK_IntegralCast,
612 E, /*base path*/ nullptr, VK_RValue);
614 cleanups->setSubExpr(E);
621 void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
622 assert(CSI.HasImplicitReturnType);
623 // If it was ever a placeholder, it had to been deduced to DependentTy.
624 assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
625 assert((!isa<LambdaScopeInfo>(CSI) || !getLangOpts().CPlusPlus14) &&
626 "lambda expressions use auto deduction in C++14 onwards");
628 // C++ core issue 975:
629 // If a lambda-expression does not include a trailing-return-type,
630 // it is as if the trailing-return-type denotes the following type:
631 // - if there are no return statements in the compound-statement,
632 // or all return statements return either an expression of type
633 // void or no expression or braced-init-list, the type void;
634 // - otherwise, if all return statements return an expression
635 // and the types of the returned expressions after
636 // lvalue-to-rvalue conversion (4.1 [conv.lval]),
637 // array-to-pointer conversion (4.2 [conv.array]), and
638 // function-to-pointer conversion (4.3 [conv.func]) are the
639 // same, that common type;
640 // - otherwise, the program is ill-formed.
642 // C++ core issue 1048 additionally removes top-level cv-qualifiers
643 // from the types of returned expressions to match the C++14 auto
646 // In addition, in blocks in non-C++ modes, if all of the return
647 // statements are enumerator-like expressions of some type T, where
648 // T has a name for linkage, then we infer the return type of the
649 // block to be that type.
651 // First case: no return statements, implicit void return type.
652 ASTContext &Ctx = getASTContext();
653 if (CSI.Returns.empty()) {
654 // It's possible there were simply no /valid/ return statements.
655 // In this case, the first one we found may have at least given us a type.
656 if (CSI.ReturnType.isNull())
657 CSI.ReturnType = Ctx.VoidTy;
661 // Second case: at least one return statement has dependent type.
662 // Delay type checking until instantiation.
663 assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
664 if (CSI.ReturnType->isDependentType())
667 // Try to apply the enum-fuzz rule.
668 if (!getLangOpts().CPlusPlus) {
669 assert(isa<BlockScopeInfo>(CSI));
670 const EnumDecl *ED = findCommonEnumForBlockReturns(CSI.Returns);
672 CSI.ReturnType = Context.getTypeDeclType(ED);
673 adjustBlockReturnsToEnum(*this, CSI.Returns, CSI.ReturnType);
678 // Third case: only one return statement. Don't bother doing extra work!
679 SmallVectorImpl<ReturnStmt*>::iterator I = CSI.Returns.begin(),
680 E = CSI.Returns.end();
684 // General case: many return statements.
685 // Check that they all have compatible return types.
687 // We require the return types to strictly match here.
688 // Note that we've already done the required promotions as part of
689 // processing the return statement.
690 for (; I != E; ++I) {
691 const ReturnStmt *RS = *I;
692 const Expr *RetE = RS->getRetValue();
694 QualType ReturnType =
695 (RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
696 if (Context.getCanonicalFunctionResultType(ReturnType) ==
697 Context.getCanonicalFunctionResultType(CSI.ReturnType))
700 // FIXME: This is a poor diagnostic for ReturnStmts without expressions.
701 // TODO: It's possible that the *first* return is the divergent one.
702 Diag(RS->getLocStart(),
703 diag::err_typecheck_missing_return_type_incompatible)
704 << ReturnType << CSI.ReturnType
705 << isa<LambdaScopeInfo>(CSI);
706 // Continue iterating so that we keep emitting diagnostics.
710 QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
715 // Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
717 QualType DeductType = Context.getAutoDeductType();
719 TLB.pushTypeSpec(DeductType).setNameLoc(Loc);
721 DeductType = BuildReferenceType(DeductType, true, Loc, Id);
722 assert(!DeductType.isNull() && "can't build reference to auto");
723 TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
725 TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
727 // Deduce the type of the init capture.
728 QualType DeducedType = deduceVarTypeFromInitializer(
729 /*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
730 SourceRange(Loc, Loc), IsDirectInit, Init);
731 if (DeducedType.isNull())
734 // Are we a non-list direct initialization?
735 ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
737 // Perform initialization analysis and ensure any implicit conversions
738 // (such as lvalue-to-rvalue) are enforced.
739 InitializedEntity Entity =
740 InitializedEntity::InitializeLambdaCapture(Id, DeducedType, Loc);
741 InitializationKind Kind =
743 ? (CXXDirectInit ? InitializationKind::CreateDirect(
744 Loc, Init->getLocStart(), Init->getLocEnd())
745 : InitializationKind::CreateDirectList(Loc))
746 : InitializationKind::CreateCopy(Loc, Init->getLocStart());
748 MultiExprArg Args = Init;
751 MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
753 InitializationSequence InitSeq(*this, Entity, Kind, Args);
754 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
756 if (Result.isInvalid())
758 Init = Result.getAs<Expr>();
760 // The init-capture initialization is a full-expression that must be
761 // processed as one before we enter the declcontext of the lambda's
763 Result = ActOnFinishFullExpr(Init, Loc, /*DiscardedValue*/ false,
764 /*IsConstexpr*/ false,
765 /*IsLambdaInitCaptureInitalizer*/ true);
766 if (Result.isInvalid())
769 Init = Result.getAs<Expr>();
773 VarDecl *Sema::createLambdaInitCaptureVarDecl(SourceLocation Loc,
774 QualType InitCaptureType,
776 unsigned InitStyle, Expr *Init) {
777 TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType,
779 // Create a dummy variable representing the init-capture. This is not actually
780 // used as a variable, and only exists as a way to name and refer to the
782 // FIXME: Pass in separate source locations for '&' and identifier.
783 VarDecl *NewVD = VarDecl::Create(Context, CurContext, Loc,
784 Loc, Id, InitCaptureType, TSI, SC_Auto);
785 NewVD->setInitCapture(true);
786 NewVD->setReferenced(true);
787 // FIXME: Pass in a VarDecl::InitializationStyle.
788 NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
789 NewVD->markUsed(Context);
790 NewVD->setInit(Init);
794 FieldDecl *Sema::buildInitCaptureField(LambdaScopeInfo *LSI, VarDecl *Var) {
795 FieldDecl *Field = FieldDecl::Create(
796 Context, LSI->Lambda, Var->getLocation(), Var->getLocation(),
797 nullptr, Var->getType(), Var->getTypeSourceInfo(), nullptr, false,
799 Field->setImplicit(true);
800 Field->setAccess(AS_private);
801 LSI->Lambda->addDecl(Field);
803 LSI->addCapture(Var, /*isBlock*/false, Var->getType()->isReferenceType(),
804 /*isNested*/false, Var->getLocation(), SourceLocation(),
805 Var->getType(), Var->getInit());
809 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
810 Declarator &ParamInfo,
812 // Determine if we're within a context where we know that the lambda will
813 // be dependent, because there are template parameters in scope.
814 bool KnownDependent = false;
815 LambdaScopeInfo *const LSI = getCurLambda();
816 assert(LSI && "LambdaScopeInfo should be on stack!");
818 // The lambda-expression's closure type might be dependent even if its
819 // semantic context isn't, if it appears within a default argument of a
820 // function template.
821 if (CurScope->getTemplateParamParent())
822 KnownDependent = true;
824 // Determine the signature of the call operator.
825 TypeSourceInfo *MethodTyInfo;
826 bool ExplicitParams = true;
827 bool ExplicitResultType = true;
828 bool ContainsUnexpandedParameterPack = false;
829 SourceLocation EndLoc;
830 SmallVector<ParmVarDecl *, 8> Params;
831 if (ParamInfo.getNumTypeObjects() == 0) {
832 // C++11 [expr.prim.lambda]p4:
833 // If a lambda-expression does not include a lambda-declarator, it is as
834 // if the lambda-declarator were ().
835 FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(
836 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
837 EPI.HasTrailingReturn = true;
838 EPI.TypeQuals |= DeclSpec::TQ_const;
839 // C++1y [expr.prim.lambda]:
840 // The lambda return type is 'auto', which is replaced by the
841 // trailing-return type if provided and/or deduced from 'return'
843 // We don't do this before C++1y, because we don't support deduced return
845 QualType DefaultTypeForNoTrailingReturn =
846 getLangOpts().CPlusPlus14 ? Context.getAutoDeductType()
847 : Context.DependentTy;
849 Context.getFunctionType(DefaultTypeForNoTrailingReturn, None, EPI);
850 MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy);
851 ExplicitParams = false;
852 ExplicitResultType = false;
853 EndLoc = Intro.Range.getEnd();
855 assert(ParamInfo.isFunctionDeclarator() &&
856 "lambda-declarator is a function");
857 DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
859 // C++11 [expr.prim.lambda]p5:
860 // This function call operator is declared const (9.3.1) if and only if
861 // the lambda-expression's parameter-declaration-clause is not followed
862 // by mutable. It is neither virtual nor declared volatile. [...]
863 if (!FTI.hasMutableQualifier())
864 FTI.TypeQuals |= DeclSpec::TQ_const;
866 MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope);
867 assert(MethodTyInfo && "no type from lambda-declarator");
868 EndLoc = ParamInfo.getSourceRange().getEnd();
870 ExplicitResultType = FTI.hasTrailingReturnType();
872 if (FTIHasNonVoidParameters(FTI)) {
873 Params.reserve(FTI.NumParams);
874 for (unsigned i = 0, e = FTI.NumParams; i != e; ++i)
875 Params.push_back(cast<ParmVarDecl>(FTI.Params[i].Param));
878 // Check for unexpanded parameter packs in the method type.
879 if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
880 ContainsUnexpandedParameterPack = true;
883 CXXRecordDecl *Class = createLambdaClosureType(Intro.Range, MethodTyInfo,
884 KnownDependent, Intro.Default);
886 CXXMethodDecl *Method = startLambdaDefinition(Class, Intro.Range,
887 MethodTyInfo, EndLoc, Params);
889 CheckCXXDefaultArguments(Method);
891 // Attributes on the lambda apply to the method.
892 ProcessDeclAttributes(CurScope, Method, ParamInfo);
894 // Introduce the function call operator as the current declaration context.
895 PushDeclContext(CurScope, Method);
897 // Build the lambda scope.
898 buildLambdaScope(LSI, Method, Intro.Range, Intro.Default, Intro.DefaultLoc,
899 ExplicitParams, ExplicitResultType, !Method->isConst());
901 // C++11 [expr.prim.lambda]p9:
902 // A lambda-expression whose smallest enclosing scope is a block scope is a
903 // local lambda expression; any other lambda expression shall not have a
904 // capture-default or simple-capture in its lambda-introducer.
906 // For simple-captures, this is covered by the check below that any named
907 // entity is a variable that can be captured.
909 // For DR1632, we also allow a capture-default in any context where we can
910 // odr-use 'this' (in particular, in a default initializer for a non-static
912 if (Intro.Default != LCD_None && !Class->getParent()->isFunctionOrMethod() &&
913 (getCurrentThisType().isNull() ||
914 CheckCXXThisCapture(SourceLocation(), /*Explicit*/true,
915 /*BuildAndDiagnose*/false)))
916 Diag(Intro.DefaultLoc, diag::err_capture_default_non_local);
918 // Distinct capture names, for diagnostics.
919 llvm::SmallSet<IdentifierInfo*, 8> CaptureNames;
921 // Handle explicit captures.
922 SourceLocation PrevCaptureLoc
923 = Intro.Default == LCD_None? Intro.Range.getBegin() : Intro.DefaultLoc;
924 for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
925 PrevCaptureLoc = C->Loc, ++C) {
926 if (C->Kind == LCK_This || C->Kind == LCK_StarThis) {
927 if (C->Kind == LCK_StarThis)
928 Diag(C->Loc, !getLangOpts().CPlusPlus1z
929 ? diag::ext_star_this_lambda_capture_cxx1z
930 : diag::warn_cxx14_compat_star_this_lambda_capture);
932 // C++11 [expr.prim.lambda]p8:
933 // An identifier or this shall not appear more than once in a
935 if (LSI->isCXXThisCaptured()) {
936 Diag(C->Loc, diag::err_capture_more_than_once)
937 << "'this'" << SourceRange(LSI->getCXXThisCapture().getLocation())
938 << FixItHint::CreateRemoval(
939 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
943 // C++1z [expr.prim.lambda]p8:
944 // If a lambda-capture includes a capture-default that is =, each
945 // simple-capture of that lambda-capture shall be of the form "&
946 // identifier" or "* this". [ Note: The form [&,this] is redundant but
947 // accepted for compatibility with ISO C++14. --end note ]
948 if (Intro.Default == LCD_ByCopy && C->Kind != LCK_StarThis) {
949 Diag(C->Loc, diag::err_this_capture_with_copy_default)
950 << FixItHint::CreateRemoval(
951 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
955 // C++11 [expr.prim.lambda]p12:
956 // If this is captured by a local lambda expression, its nearest
957 // enclosing function shall be a non-static member function.
958 QualType ThisCaptureType = getCurrentThisType();
959 if (ThisCaptureType.isNull()) {
960 Diag(C->Loc, diag::err_this_capture) << true;
964 CheckCXXThisCapture(C->Loc, /*Explicit=*/true, /*BuildAndDiagnose*/ true,
965 /*FunctionScopeIndexToStopAtPtr*/ nullptr,
966 C->Kind == LCK_StarThis);
970 assert(C->Id && "missing identifier for capture");
972 if (C->Init.isInvalid())
975 VarDecl *Var = nullptr;
976 if (C->Init.isUsable()) {
977 Diag(C->Loc, getLangOpts().CPlusPlus14
978 ? diag::warn_cxx11_compat_init_capture
979 : diag::ext_init_capture);
981 if (C->Init.get()->containsUnexpandedParameterPack())
982 ContainsUnexpandedParameterPack = true;
983 // If the initializer expression is usable, but the InitCaptureType
984 // is not, then an error has occurred - so ignore the capture for now.
985 // for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
986 // FIXME: we should create the init capture variable and mark it invalid
988 if (C->InitCaptureType.get().isNull())
992 switch (C->InitKind) {
993 case LambdaCaptureInitKind::NoInit:
994 llvm_unreachable("not an init-capture?");
995 case LambdaCaptureInitKind::CopyInit:
996 InitStyle = VarDecl::CInit;
998 case LambdaCaptureInitKind::DirectInit:
999 InitStyle = VarDecl::CallInit;
1001 case LambdaCaptureInitKind::ListInit:
1002 InitStyle = VarDecl::ListInit;
1005 Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
1006 C->Id, InitStyle, C->Init.get());
1007 // C++1y [expr.prim.lambda]p11:
1008 // An init-capture behaves as if it declares and explicitly
1009 // captures a variable [...] whose declarative region is the
1010 // lambda-expression's compound-statement
1012 PushOnScopeChains(Var, CurScope, false);
1014 assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
1015 "init capture has valid but null init?");
1017 // C++11 [expr.prim.lambda]p8:
1018 // If a lambda-capture includes a capture-default that is &, the
1019 // identifiers in the lambda-capture shall not be preceded by &.
1020 // If a lambda-capture includes a capture-default that is =, [...]
1021 // each identifier it contains shall be preceded by &.
1022 if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
1023 Diag(C->Loc, diag::err_reference_capture_with_reference_default)
1024 << FixItHint::CreateRemoval(
1025 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1027 } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
1028 Diag(C->Loc, diag::err_copy_capture_with_copy_default)
1029 << FixItHint::CreateRemoval(
1030 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1034 // C++11 [expr.prim.lambda]p10:
1035 // The identifiers in a capture-list are looked up using the usual
1036 // rules for unqualified name lookup (3.4.1)
1037 DeclarationNameInfo Name(C->Id, C->Loc);
1038 LookupResult R(*this, Name, LookupOrdinaryName);
1039 LookupName(R, CurScope);
1040 if (R.isAmbiguous())
1043 // FIXME: Disable corrections that would add qualification?
1044 CXXScopeSpec ScopeSpec;
1045 if (DiagnoseEmptyLookup(CurScope, ScopeSpec, R,
1046 llvm::make_unique<DeclFilterCCC<VarDecl>>()))
1050 Var = R.getAsSingle<VarDecl>();
1051 if (Var && DiagnoseUseOfDecl(Var, C->Loc))
1055 // C++11 [expr.prim.lambda]p8:
1056 // An identifier or this shall not appear more than once in a
1058 if (!CaptureNames.insert(C->Id).second) {
1059 if (Var && LSI->isCaptured(Var)) {
1060 Diag(C->Loc, diag::err_capture_more_than_once)
1061 << C->Id << SourceRange(LSI->getCapture(Var).getLocation())
1062 << FixItHint::CreateRemoval(
1063 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
1065 // Previous capture captured something different (one or both was
1066 // an init-cpature): no fixit.
1067 Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
1071 // C++11 [expr.prim.lambda]p10:
1072 // [...] each such lookup shall find a variable with automatic storage
1073 // duration declared in the reaching scope of the local lambda expression.
1074 // Note that the 'reaching scope' check happens in tryCaptureVariable().
1076 Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id;
1080 // Ignore invalid decls; they'll just confuse the code later.
1081 if (Var->isInvalidDecl())
1084 if (!Var->hasLocalStorage()) {
1085 Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id;
1086 Diag(Var->getLocation(), diag::note_previous_decl) << C->Id;
1090 // C++11 [expr.prim.lambda]p23:
1091 // A capture followed by an ellipsis is a pack expansion (14.5.3).
1092 SourceLocation EllipsisLoc;
1093 if (C->EllipsisLoc.isValid()) {
1094 if (Var->isParameterPack()) {
1095 EllipsisLoc = C->EllipsisLoc;
1097 Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
1098 << SourceRange(C->Loc);
1100 // Just ignore the ellipsis.
1102 } else if (Var->isParameterPack()) {
1103 ContainsUnexpandedParameterPack = true;
1106 if (C->Init.isUsable()) {
1107 buildInitCaptureField(LSI, Var);
1109 TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef :
1110 TryCapture_ExplicitByVal;
1111 tryCaptureVariable(Var, C->Loc, Kind, EllipsisLoc);
1114 finishLambdaExplicitCaptures(LSI);
1116 LSI->ContainsUnexpandedParameterPack = ContainsUnexpandedParameterPack;
1118 // Add lambda parameters into scope.
1119 addLambdaParameters(Method, CurScope);
1121 // Enter a new evaluation context to insulate the lambda from any
1122 // cleanups from the enclosing full-expression.
1123 PushExpressionEvaluationContext(PotentiallyEvaluated);
1126 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
1127 bool IsInstantiation) {
1128 LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
1130 // Leave the expression-evaluation context.
1131 DiscardCleanupsInEvaluationContext();
1132 PopExpressionEvaluationContext();
1134 // Leave the context of the lambda.
1135 if (!IsInstantiation)
1138 // Finalize the lambda.
1139 CXXRecordDecl *Class = LSI->Lambda;
1140 Class->setInvalidDecl();
1141 SmallVector<Decl*, 4> Fields(Class->fields());
1142 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1143 SourceLocation(), nullptr);
1144 CheckCompletedCXXClass(Class);
1146 PopFunctionScopeInfo();
1149 /// \brief Add a lambda's conversion to function pointer, as described in
1150 /// C++11 [expr.prim.lambda]p6.
1151 static void addFunctionPointerConversion(Sema &S,
1152 SourceRange IntroducerRange,
1153 CXXRecordDecl *Class,
1154 CXXMethodDecl *CallOperator) {
1155 // This conversion is explicitly disabled if the lambda's function has
1156 // pass_object_size attributes on any of its parameters.
1157 if (llvm::any_of(CallOperator->parameters(),
1158 std::mem_fn(&ParmVarDecl::hasAttr<PassObjectSizeAttr>)))
1161 // Add the conversion to function pointer.
1162 const FunctionProtoType *CallOpProto =
1163 CallOperator->getType()->getAs<FunctionProtoType>();
1164 const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
1165 CallOpProto->getExtProtoInfo();
1166 QualType PtrToFunctionTy;
1167 QualType InvokerFunctionTy;
1169 FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
1170 CallingConv CC = S.Context.getDefaultCallingConvention(
1171 CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
1172 InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(CC);
1173 InvokerExtInfo.TypeQuals = 0;
1174 assert(InvokerExtInfo.RefQualifier == RQ_None &&
1175 "Lambda's call operator should not have a reference qualifier");
1177 S.Context.getFunctionType(CallOpProto->getReturnType(),
1178 CallOpProto->getParamTypes(), InvokerExtInfo);
1179 PtrToFunctionTy = S.Context.getPointerType(InvokerFunctionTy);
1182 // Create the type of the conversion function.
1183 FunctionProtoType::ExtProtoInfo ConvExtInfo(
1184 S.Context.getDefaultCallingConvention(
1185 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1186 // The conversion function is always const.
1187 ConvExtInfo.TypeQuals = Qualifiers::Const;
1189 S.Context.getFunctionType(PtrToFunctionTy, None, ConvExtInfo);
1191 SourceLocation Loc = IntroducerRange.getBegin();
1192 DeclarationName ConversionName
1193 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1194 S.Context.getCanonicalType(PtrToFunctionTy));
1195 DeclarationNameLoc ConvNameLoc;
1196 // Construct a TypeSourceInfo for the conversion function, and wire
1197 // all the parameters appropriately for the FunctionProtoTypeLoc
1198 // so that everything works during transformation/instantiation of
1200 // The main reason for wiring up the parameters of the conversion
1201 // function with that of the call operator is so that constructs
1202 // like the following work:
1203 // auto L = [](auto b) { <-- 1
1204 // return [](auto a) -> decltype(a) { <-- 2
1208 // int (*fp)(int) = L(5);
1209 // Because the trailing return type can contain DeclRefExprs that refer
1210 // to the original call operator's variables, we hijack the call
1211 // operators ParmVarDecls below.
1212 TypeSourceInfo *ConvNamePtrToFunctionTSI =
1213 S.Context.getTrivialTypeSourceInfo(PtrToFunctionTy, Loc);
1214 ConvNameLoc.NamedType.TInfo = ConvNamePtrToFunctionTSI;
1216 // The conversion function is a conversion to a pointer-to-function.
1217 TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(ConvTy, Loc);
1218 FunctionProtoTypeLoc ConvTL =
1219 ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
1220 // Get the result of the conversion function which is a pointer-to-function.
1221 PointerTypeLoc PtrToFunctionTL =
1222 ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
1223 // Do the same for the TypeSourceInfo that is used to name the conversion
1225 PointerTypeLoc ConvNamePtrToFunctionTL =
1226 ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
1228 // Get the underlying function types that the conversion function will
1229 // be converting to (should match the type of the call operator).
1230 FunctionProtoTypeLoc CallOpConvTL =
1231 PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1232 FunctionProtoTypeLoc CallOpConvNameTL =
1233 ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
1235 // Wire up the FunctionProtoTypeLocs with the call operator's parameters.
1236 // These parameter's are essentially used to transform the name and
1237 // the type of the conversion operator. By using the same parameters
1238 // as the call operator's we don't have to fix any back references that
1239 // the trailing return type of the call operator's uses (such as
1240 // decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
1241 // - we can simply use the return type of the call operator, and
1242 // everything should work.
1243 SmallVector<ParmVarDecl *, 4> InvokerParams;
1244 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1245 ParmVarDecl *From = CallOperator->getParamDecl(I);
1247 InvokerParams.push_back(ParmVarDecl::Create(S.Context,
1248 // Temporarily add to the TU. This is set to the invoker below.
1249 S.Context.getTranslationUnitDecl(),
1250 From->getLocStart(),
1251 From->getLocation(),
1252 From->getIdentifier(),
1254 From->getTypeSourceInfo(),
1255 From->getStorageClass(),
1256 /*DefaultArg=*/nullptr));
1257 CallOpConvTL.setParam(I, From);
1258 CallOpConvNameTL.setParam(I, From);
1261 CXXConversionDecl *Conversion
1262 = CXXConversionDecl::Create(S.Context, Class, Loc,
1263 DeclarationNameInfo(ConversionName,
1267 /*isInline=*/true, /*isExplicit=*/false,
1268 /*isConstexpr=*/false,
1269 CallOperator->getBody()->getLocEnd());
1270 Conversion->setAccess(AS_public);
1271 Conversion->setImplicit(true);
1273 if (Class->isGenericLambda()) {
1274 // Create a template version of the conversion operator, using the template
1275 // parameter list of the function call operator.
1276 FunctionTemplateDecl *TemplateCallOperator =
1277 CallOperator->getDescribedFunctionTemplate();
1278 FunctionTemplateDecl *ConversionTemplate =
1279 FunctionTemplateDecl::Create(S.Context, Class,
1280 Loc, ConversionName,
1281 TemplateCallOperator->getTemplateParameters(),
1283 ConversionTemplate->setAccess(AS_public);
1284 ConversionTemplate->setImplicit(true);
1285 Conversion->setDescribedFunctionTemplate(ConversionTemplate);
1286 Class->addDecl(ConversionTemplate);
1288 Class->addDecl(Conversion);
1289 // Add a non-static member function that will be the result of
1290 // the conversion with a certain unique ID.
1291 DeclarationName InvokerName = &S.Context.Idents.get(
1292 getLambdaStaticInvokerName());
1293 // FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
1294 // we should get a prebuilt TrivialTypeSourceInfo from Context
1295 // using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
1296 // then rewire the parameters accordingly, by hoisting up the InvokeParams
1297 // loop below and then use its Params to set Invoke->setParams(...) below.
1298 // This would avoid the 'const' qualifier of the calloperator from
1299 // contaminating the type of the invoker, which is currently adjusted
1300 // in SemaTemplateDeduction.cpp:DeduceTemplateArguments. Fixing the
1301 // trailing return type of the invoker would require a visitor to rebuild
1302 // the trailing return type and adjusting all back DeclRefExpr's to refer
1303 // to the new static invoker parameters - not the call operator's.
1304 CXXMethodDecl *Invoke
1305 = CXXMethodDecl::Create(S.Context, Class, Loc,
1306 DeclarationNameInfo(InvokerName, Loc),
1308 CallOperator->getTypeSourceInfo(),
1309 SC_Static, /*IsInline=*/true,
1310 /*IsConstexpr=*/false,
1311 CallOperator->getBody()->getLocEnd());
1312 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
1313 InvokerParams[I]->setOwningFunction(Invoke);
1314 Invoke->setParams(InvokerParams);
1315 Invoke->setAccess(AS_private);
1316 Invoke->setImplicit(true);
1317 if (Class->isGenericLambda()) {
1318 FunctionTemplateDecl *TemplateCallOperator =
1319 CallOperator->getDescribedFunctionTemplate();
1320 FunctionTemplateDecl *StaticInvokerTemplate = FunctionTemplateDecl::Create(
1321 S.Context, Class, Loc, InvokerName,
1322 TemplateCallOperator->getTemplateParameters(),
1324 StaticInvokerTemplate->setAccess(AS_private);
1325 StaticInvokerTemplate->setImplicit(true);
1326 Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
1327 Class->addDecl(StaticInvokerTemplate);
1329 Class->addDecl(Invoke);
1332 /// \brief Add a lambda's conversion to block pointer.
1333 static void addBlockPointerConversion(Sema &S,
1334 SourceRange IntroducerRange,
1335 CXXRecordDecl *Class,
1336 CXXMethodDecl *CallOperator) {
1337 const FunctionProtoType *Proto =
1338 CallOperator->getType()->getAs<FunctionProtoType>();
1340 // The function type inside the block pointer type is the same as the call
1341 // operator with some tweaks. The calling convention is the default free
1342 // function convention, and the type qualifications are lost.
1343 FunctionProtoType::ExtProtoInfo BlockEPI = Proto->getExtProtoInfo();
1345 BlockEPI.ExtInfo.withCallingConv(S.Context.getDefaultCallingConvention(
1346 Proto->isVariadic(), /*IsCXXMethod=*/false));
1347 BlockEPI.TypeQuals = 0;
1348 QualType FunctionTy = S.Context.getFunctionType(
1349 Proto->getReturnType(), Proto->getParamTypes(), BlockEPI);
1350 QualType BlockPtrTy = S.Context.getBlockPointerType(FunctionTy);
1352 FunctionProtoType::ExtProtoInfo ConversionEPI(
1353 S.Context.getDefaultCallingConvention(
1354 /*IsVariadic=*/false, /*IsCXXMethod=*/true));
1355 ConversionEPI.TypeQuals = Qualifiers::Const;
1356 QualType ConvTy = S.Context.getFunctionType(BlockPtrTy, None, ConversionEPI);
1358 SourceLocation Loc = IntroducerRange.getBegin();
1359 DeclarationName Name
1360 = S.Context.DeclarationNames.getCXXConversionFunctionName(
1361 S.Context.getCanonicalType(BlockPtrTy));
1362 DeclarationNameLoc NameLoc;
1363 NameLoc.NamedType.TInfo = S.Context.getTrivialTypeSourceInfo(BlockPtrTy, Loc);
1364 CXXConversionDecl *Conversion
1365 = CXXConversionDecl::Create(S.Context, Class, Loc,
1366 DeclarationNameInfo(Name, Loc, NameLoc),
1368 S.Context.getTrivialTypeSourceInfo(ConvTy, Loc),
1369 /*isInline=*/true, /*isExplicit=*/false,
1370 /*isConstexpr=*/false,
1371 CallOperator->getBody()->getLocEnd());
1372 Conversion->setAccess(AS_public);
1373 Conversion->setImplicit(true);
1374 Class->addDecl(Conversion);
1377 static ExprResult performLambdaVarCaptureInitialization(
1378 Sema &S, LambdaScopeInfo::Capture &Capture,
1380 SmallVectorImpl<VarDecl *> &ArrayIndexVars,
1381 SmallVectorImpl<unsigned> &ArrayIndexStarts) {
1382 assert(Capture.isVariableCapture() && "not a variable capture");
1384 auto *Var = Capture.getVariable();
1385 SourceLocation Loc = Capture.getLocation();
1387 // C++11 [expr.prim.lambda]p21:
1388 // When the lambda-expression is evaluated, the entities that
1389 // are captured by copy are used to direct-initialize each
1390 // corresponding non-static data member of the resulting closure
1391 // object. (For array members, the array elements are
1392 // direct-initialized in increasing subscript order.) These
1393 // initializations are performed in the (unspecified) order in
1394 // which the non-static data members are declared.
1396 // C++ [expr.prim.lambda]p12:
1397 // An entity captured by a lambda-expression is odr-used (3.2) in
1398 // the scope containing the lambda-expression.
1399 ExprResult RefResult = S.BuildDeclarationNameExpr(
1400 CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
1401 if (RefResult.isInvalid())
1403 Expr *Ref = RefResult.get();
1405 QualType FieldType = Field->getType();
1407 // When the variable has array type, create index variables for each
1408 // dimension of the array. We use these index variables to subscript
1409 // the source array, and other clients (e.g., CodeGen) will perform
1410 // the necessary iteration with these index variables.
1412 // FIXME: This is dumb. Add a proper AST representation for array
1413 // copy-construction and use it here.
1414 SmallVector<VarDecl *, 4> IndexVariables;
1415 QualType BaseType = FieldType;
1416 QualType SizeType = S.Context.getSizeType();
1417 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1418 while (const ConstantArrayType *Array
1419 = S.Context.getAsConstantArrayType(BaseType)) {
1420 // Create the iteration variable for this array index.
1421 IdentifierInfo *IterationVarName = nullptr;
1424 llvm::raw_svector_ostream OS(Str);
1425 OS << "__i" << IndexVariables.size();
1426 IterationVarName = &S.Context.Idents.get(OS.str());
1428 VarDecl *IterationVar = VarDecl::Create(
1429 S.Context, S.CurContext, Loc, Loc, IterationVarName, SizeType,
1430 S.Context.getTrivialTypeSourceInfo(SizeType, Loc), SC_None);
1431 IterationVar->setImplicit();
1432 IndexVariables.push_back(IterationVar);
1433 ArrayIndexVars.push_back(IterationVar);
1435 // Create a reference to the iteration variable.
1436 ExprResult IterationVarRef =
1437 S.BuildDeclRefExpr(IterationVar, SizeType, VK_LValue, Loc);
1438 assert(!IterationVarRef.isInvalid() &&
1439 "Reference to invented variable cannot fail!");
1440 IterationVarRef = S.DefaultLvalueConversion(IterationVarRef.get());
1441 assert(!IterationVarRef.isInvalid() &&
1442 "Conversion of invented variable cannot fail!");
1444 // Subscript the array with this iteration variable.
1445 ExprResult Subscript =
1446 S.CreateBuiltinArraySubscriptExpr(Ref, Loc, IterationVarRef.get(), Loc);
1447 if (Subscript.isInvalid())
1450 Ref = Subscript.get();
1451 BaseType = Array->getElementType();
1454 // Construct the entity that we will be initializing. For an array, this
1455 // will be first element in the array, which may require several levels
1456 // of array-subscript entities.
1457 SmallVector<InitializedEntity, 4> Entities;
1458 Entities.reserve(1 + IndexVariables.size());
1459 Entities.push_back(InitializedEntity::InitializeLambdaCapture(
1460 Var->getIdentifier(), FieldType, Loc));
1461 for (unsigned I = 0, N = IndexVariables.size(); I != N; ++I)
1463 InitializedEntity::InitializeElement(S.Context, 0, Entities.back()));
1465 InitializationKind InitKind = InitializationKind::CreateDirect(Loc, Loc, Loc);
1466 InitializationSequence Init(S, Entities.back(), InitKind, Ref);
1467 return Init.Perform(S, Entities.back(), InitKind, Ref);
1470 ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
1472 LambdaScopeInfo LSI = *cast<LambdaScopeInfo>(FunctionScopes.back());
1473 ActOnFinishFunctionBody(LSI.CallOperator, Body);
1474 return BuildLambdaExpr(StartLoc, Body->getLocEnd(), &LSI);
1477 static LambdaCaptureDefault
1478 mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
1480 case CapturingScopeInfo::ImpCap_None:
1482 case CapturingScopeInfo::ImpCap_LambdaByval:
1484 case CapturingScopeInfo::ImpCap_CapturedRegion:
1485 case CapturingScopeInfo::ImpCap_LambdaByref:
1487 case CapturingScopeInfo::ImpCap_Block:
1488 llvm_unreachable("block capture in lambda");
1490 llvm_unreachable("Unknown implicit capture style");
1493 ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
1494 LambdaScopeInfo *LSI) {
1495 // Collect information from the lambda scope.
1496 SmallVector<LambdaCapture, 4> Captures;
1497 SmallVector<Expr *, 4> CaptureInits;
1498 SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
1499 LambdaCaptureDefault CaptureDefault =
1500 mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
1501 CXXRecordDecl *Class;
1502 CXXMethodDecl *CallOperator;
1503 SourceRange IntroducerRange;
1504 bool ExplicitParams;
1505 bool ExplicitResultType;
1506 CleanupInfo LambdaCleanup;
1507 bool ContainsUnexpandedParameterPack;
1508 SmallVector<VarDecl *, 4> ArrayIndexVars;
1509 SmallVector<unsigned, 4> ArrayIndexStarts;
1511 CallOperator = LSI->CallOperator;
1512 Class = LSI->Lambda;
1513 IntroducerRange = LSI->IntroducerRange;
1514 ExplicitParams = LSI->ExplicitParams;
1515 ExplicitResultType = !LSI->HasImplicitReturnType;
1516 LambdaCleanup = LSI->Cleanup;
1517 ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
1519 CallOperator->setLexicalDeclContext(Class);
1520 Decl *TemplateOrNonTemplateCallOperatorDecl =
1521 CallOperator->getDescribedFunctionTemplate()
1522 ? CallOperator->getDescribedFunctionTemplate()
1523 : cast<Decl>(CallOperator);
1525 TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
1526 Class->addDecl(TemplateOrNonTemplateCallOperatorDecl);
1528 PopExpressionEvaluationContext();
1530 // Translate captures.
1531 auto CurField = Class->field_begin();
1532 for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I, ++CurField) {
1533 LambdaScopeInfo::Capture From = LSI->Captures[I];
1534 assert(!From.isBlockCapture() && "Cannot capture __block variables");
1535 bool IsImplicit = I >= LSI->NumExplicitCaptures;
1537 // Handle 'this' capture.
1538 if (From.isThisCapture()) {
1540 LambdaCapture(From.getLocation(), IsImplicit,
1541 From.isCopyCapture() ? LCK_StarThis : LCK_This));
1542 CaptureInits.push_back(From.getInitExpr());
1543 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1546 if (From.isVLATypeCapture()) {
1548 LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType));
1549 CaptureInits.push_back(nullptr);
1550 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1554 VarDecl *Var = From.getVariable();
1555 LambdaCaptureKind Kind = From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
1556 Captures.push_back(LambdaCapture(From.getLocation(), IsImplicit, Kind,
1557 Var, From.getEllipsisLoc()));
1558 Expr *Init = From.getInitExpr();
1560 auto InitResult = performLambdaVarCaptureInitialization(
1561 *this, From, *CurField, ArrayIndexVars, ArrayIndexStarts);
1562 if (InitResult.isInvalid())
1564 Init = InitResult.get();
1566 ArrayIndexStarts.push_back(ArrayIndexVars.size());
1568 CaptureInits.push_back(Init);
1571 // C++11 [expr.prim.lambda]p6:
1572 // The closure type for a lambda-expression with no lambda-capture
1573 // has a public non-virtual non-explicit const conversion function
1574 // to pointer to function having the same parameter and return
1575 // types as the closure type's function call operator.
1576 if (Captures.empty() && CaptureDefault == LCD_None)
1577 addFunctionPointerConversion(*this, IntroducerRange, Class,
1581 // The closure type for a lambda-expression has a public non-virtual
1582 // non-explicit const conversion function to a block pointer having the
1583 // same parameter and return types as the closure type's function call
1585 // FIXME: Fix generic lambda to block conversions.
1586 if (getLangOpts().Blocks && getLangOpts().ObjC1 &&
1587 !Class->isGenericLambda())
1588 addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
1590 // Finalize the lambda class.
1591 SmallVector<Decl*, 4> Fields(Class->fields());
1592 ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
1593 SourceLocation(), nullptr);
1594 CheckCompletedCXXClass(Class);
1597 Cleanup.mergeFrom(LambdaCleanup);
1599 LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange,
1600 CaptureDefault, CaptureDefaultLoc,
1602 ExplicitParams, ExplicitResultType,
1603 CaptureInits, ArrayIndexVars,
1604 ArrayIndexStarts, EndLoc,
1605 ContainsUnexpandedParameterPack);
1607 if (!CurContext->isDependentContext()) {
1608 switch (ExprEvalContexts.back().Context) {
1609 // C++11 [expr.prim.lambda]p2:
1610 // A lambda-expression shall not appear in an unevaluated operand
1613 case UnevaluatedAbstract:
1614 // C++1y [expr.const]p2:
1615 // A conditional-expression e is a core constant expression unless the
1616 // evaluation of e, following the rules of the abstract machine, would
1617 // evaluate [...] a lambda-expression.
1619 // This is technically incorrect, there are some constant evaluated contexts
1620 // where this should be allowed. We should probably fix this when DR1607 is
1621 // ratified, it lays out the exact set of conditions where we shouldn't
1622 // allow a lambda-expression.
1623 case ConstantEvaluated:
1624 // We don't actually diagnose this case immediately, because we
1625 // could be within a context where we might find out later that
1626 // the expression is potentially evaluated (e.g., for typeid).
1627 ExprEvalContexts.back().Lambdas.push_back(Lambda);
1630 case DiscardedStatement:
1631 case PotentiallyEvaluated:
1632 case PotentiallyEvaluatedIfUsed:
1637 return MaybeBindToTemporary(Lambda);
1640 ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
1641 SourceLocation ConvLocation,
1642 CXXConversionDecl *Conv,
1644 // Make sure that the lambda call operator is marked used.
1645 CXXRecordDecl *Lambda = Conv->getParent();
1646 CXXMethodDecl *CallOperator
1647 = cast<CXXMethodDecl>(
1649 Context.DeclarationNames.getCXXOperatorName(OO_Call)).front());
1650 CallOperator->setReferenced();
1651 CallOperator->markUsed(Context);
1653 ExprResult Init = PerformCopyInitialization(
1654 InitializedEntity::InitializeBlock(ConvLocation,
1657 CurrentLocation, Src);
1658 if (!Init.isInvalid())
1659 Init = ActOnFinishFullExpr(Init.get());
1661 if (Init.isInvalid())
1664 // Create the new block to be returned.
1665 BlockDecl *Block = BlockDecl::Create(Context, CurContext, ConvLocation);
1667 // Set the type information.
1668 Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
1669 Block->setIsVariadic(CallOperator->isVariadic());
1670 Block->setBlockMissingReturnType(false);
1673 SmallVector<ParmVarDecl *, 4> BlockParams;
1674 for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
1675 ParmVarDecl *From = CallOperator->getParamDecl(I);
1676 BlockParams.push_back(ParmVarDecl::Create(Context, Block,
1677 From->getLocStart(),
1678 From->getLocation(),
1679 From->getIdentifier(),
1681 From->getTypeSourceInfo(),
1682 From->getStorageClass(),
1683 /*DefaultArg=*/nullptr));
1685 Block->setParams(BlockParams);
1687 Block->setIsConversionFromLambda(true);
1689 // Add capture. The capture uses a fake variable, which doesn't correspond
1690 // to any actual memory location. However, the initializer copy-initializes
1691 // the lambda object.
1692 TypeSourceInfo *CapVarTSI =
1693 Context.getTrivialTypeSourceInfo(Src->getType());
1694 VarDecl *CapVar = VarDecl::Create(Context, Block, ConvLocation,
1695 ConvLocation, nullptr,
1696 Src->getType(), CapVarTSI,
1698 BlockDecl::Capture Capture(/*Variable=*/CapVar, /*ByRef=*/false,
1699 /*Nested=*/false, /*Copy=*/Init.get());
1700 Block->setCaptures(Context, Capture, /*CapturesCXXThis=*/false);
1702 // Add a fake function body to the block. IR generation is responsible
1703 // for filling in the actual body, which cannot be expressed as an AST.
1704 Block->setBody(new (Context) CompoundStmt(ConvLocation));
1706 // Create the block literal expression.
1707 Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
1708 ExprCleanupObjects.push_back(Block);
1709 Cleanup.setExprNeedsCleanups(true);