| //===--- SemaLambda.cpp - Semantic Analysis for C++11 Lambdas -------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements semantic analysis for C++ lambda expressions. |
| // |
| //===----------------------------------------------------------------------===// |
| #include "clang/Sema/DeclSpec.h" |
| #include "clang/Sema/Initialization.h" |
| #include "clang/Sema/Lookup.h" |
| #include "clang/Sema/ScopeInfo.h" |
| #include "clang/Sema/SemaInternal.h" |
| #include "clang/Lex/Preprocessor.h" |
| #include "clang/AST/ExprCXX.h" |
| using namespace clang; |
| using namespace sema; |
| |
| void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro, |
| Declarator &ParamInfo, |
| Scope *CurScope) { |
| DeclContext *DC = CurContext; |
| while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext())) |
| DC = DC->getParent(); |
| |
| // Start constructing the lambda class. |
| CXXRecordDecl *Class = CXXRecordDecl::Create(Context, TTK_Class, DC, |
| Intro.Range.getBegin(), |
| /*IdLoc=*/Intro.Range.getBegin(), |
| /*Id=*/0); |
| Class->startDefinition(); |
| Class->makeLambda(); |
| CurContext->addDecl(Class); |
| |
| // Build the call operator; we don't really have all the relevant information |
| // at this point, but we need something to attach child declarations to. |
| QualType MethodTy; |
| TypeSourceInfo *MethodTyInfo; |
| bool ExplicitParams = true; |
| SourceLocation EndLoc; |
| if (ParamInfo.getNumTypeObjects() == 0) { |
| // C++11 [expr.prim.lambda]p4: |
| // If a lambda-expression does not include a lambda-declarator, it is as |
| // if the lambda-declarator were (). |
| FunctionProtoType::ExtProtoInfo EPI; |
| EPI.HasTrailingReturn = true; |
| EPI.TypeQuals |= DeclSpec::TQ_const; |
| MethodTy = Context.getFunctionType(Context.DependentTy, |
| /*Args=*/0, /*NumArgs=*/0, EPI); |
| MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy); |
| ExplicitParams = false; |
| EndLoc = Intro.Range.getEnd(); |
| } else { |
| assert(ParamInfo.isFunctionDeclarator() && |
| "lambda-declarator is a function"); |
| DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo(); |
| |
| // C++11 [expr.prim.lambda]p5: |
| // This function call operator is declared const (9.3.1) if and only if |
| // the lambda-expression's parameter-declaration-clause is not followed |
| // by mutable. It is neither virtual nor declared volatile. [...] |
| if (!FTI.hasMutableQualifier()) |
| FTI.TypeQuals |= DeclSpec::TQ_const; |
| |
| // C++11 [expr.prim.lambda]p5: |
| // [...] Default arguments (8.3.6) shall not be specified in the |
| // parameter-declaration-clause of a lambda-declarator. |
| CheckExtraCXXDefaultArguments(ParamInfo); |
| |
| MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope); |
| // FIXME: Can these asserts actually fail? |
| assert(MethodTyInfo && "no type from lambda-declarator"); |
| MethodTy = MethodTyInfo->getType(); |
| assert(!MethodTy.isNull() && "no type from lambda declarator"); |
| EndLoc = ParamInfo.getSourceRange().getEnd(); |
| } |
| |
| // C++11 [expr.prim.lambda]p5: |
| // The closure type for a lambda-expression has a public inline function |
| // call operator (13.5.4) whose parameters and return type are described by |
| // the lambda-expression's parameter-declaration-clause and |
| // trailing-return-type respectively. |
| DeclarationName MethodName |
| = Context.DeclarationNames.getCXXOperatorName(OO_Call); |
| DeclarationNameLoc MethodNameLoc; |
| MethodNameLoc.CXXOperatorName.BeginOpNameLoc |
| = Intro.Range.getBegin().getRawEncoding(); |
| MethodNameLoc.CXXOperatorName.EndOpNameLoc |
| = Intro.Range.getEnd().getRawEncoding(); |
| CXXMethodDecl *Method |
| = CXXMethodDecl::Create(Context, Class, EndLoc, |
| DeclarationNameInfo(MethodName, |
| Intro.Range.getBegin(), |
| MethodNameLoc), |
| MethodTy, MethodTyInfo, |
| /*isStatic=*/false, |
| SC_None, |
| /*isInline=*/true, |
| /*isConstExpr=*/false, |
| EndLoc); |
| Method->setAccess(AS_public); |
| |
| // Temporarily set the lexical declaration context to the current |
| // context, so that the Scope stack matches the lexical nesting. |
| Method->setLexicalDeclContext(DC); |
| |
| // Attributes on the lambda apply to the method. |
| ProcessDeclAttributes(CurScope, Method, ParamInfo); |
| |
| // Introduce the function call operator as the current declaration context. |
| PushDeclContext(CurScope, Method); |
| |
| // Introduce the lambda scope. |
| PushLambdaScope(Class, Method); |
| LambdaScopeInfo *LSI = getCurLambda(); |
| if (Intro.Default == LCD_ByCopy) |
| LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval; |
| else if (Intro.Default == LCD_ByRef) |
| LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref; |
| LSI->IntroducerRange = Intro.Range; |
| LSI->ExplicitParams = ExplicitParams; |
| LSI->Mutable = (Method->getTypeQualifiers() & Qualifiers::Const) == 0; |
| |
| // Handle explicit captures. |
| SourceLocation PrevCaptureLoc |
| = Intro.Default == LCD_None? Intro.Range.getBegin() : Intro.DefaultLoc; |
| for (llvm::SmallVector<LambdaCapture, 4>::const_iterator |
| C = Intro.Captures.begin(), |
| E = Intro.Captures.end(); |
| C != E; |
| PrevCaptureLoc = C->Loc, ++C) { |
| if (C->Kind == LCK_This) { |
| // C++11 [expr.prim.lambda]p8: |
| // An identifier or this shall not appear more than once in a |
| // lambda-capture. |
| if (LSI->isCXXThisCaptured()) { |
| Diag(C->Loc, diag::err_capture_more_than_once) |
| << "'this'" |
| << SourceRange(LSI->getCXXThisCapture().getLocation()) |
| << FixItHint::CreateRemoval( |
| SourceRange(PP.getLocForEndOfToken(PrevCaptureLoc), C->Loc)); |
| continue; |
| } |
| |
| // C++11 [expr.prim.lambda]p8: |
| // If a lambda-capture includes a capture-default that is =, the |
| // lambda-capture shall not contain this [...]. |
| if (Intro.Default == LCD_ByCopy) { |
| Diag(C->Loc, diag::err_this_capture_with_copy_default) |
| << FixItHint::CreateRemoval( |
| SourceRange(PP.getLocForEndOfToken(PrevCaptureLoc), C->Loc)); |
| continue; |
| } |
| |
| // C++11 [expr.prim.lambda]p12: |
| // If this is captured by a local lambda expression, its nearest |
| // enclosing function shall be a non-static member function. |
| QualType ThisCaptureType = getCurrentThisType(); |
| if (ThisCaptureType.isNull()) { |
| Diag(C->Loc, diag::err_this_capture) << true; |
| continue; |
| } |
| |
| CheckCXXThisCapture(C->Loc, /*Explicit=*/true); |
| continue; |
| } |
| |
| assert(C->Id && "missing identifier for capture"); |
| |
| // C++11 [expr.prim.lambda]p8: |
| // If a lambda-capture includes a capture-default that is &, the |
| // identifiers in the lambda-capture shall not be preceded by &. |
| // If a lambda-capture includes a capture-default that is =, [...] |
| // each identifier it contains shall be preceded by &. |
| if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) { |
| Diag(C->Loc, diag::err_reference_capture_with_reference_default) |
| << FixItHint::CreateRemoval( |
| SourceRange(PP.getLocForEndOfToken(PrevCaptureLoc), C->Loc)); |
| continue; |
| } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) { |
| Diag(C->Loc, diag::err_copy_capture_with_copy_default) |
| << FixItHint::CreateRemoval( |
| SourceRange(PP.getLocForEndOfToken(PrevCaptureLoc), C->Loc)); |
| continue; |
| } |
| |
| DeclarationNameInfo Name(C->Id, C->Loc); |
| LookupResult R(*this, Name, LookupOrdinaryName); |
| LookupName(R, CurScope); |
| if (R.isAmbiguous()) |
| continue; |
| if (R.empty()) { |
| // FIXME: Disable corrections that would add qualification? |
| CXXScopeSpec ScopeSpec; |
| DeclFilterCCC<VarDecl> Validator; |
| if (DiagnoseEmptyLookup(CurScope, ScopeSpec, R, Validator)) |
| continue; |
| } |
| |
| // C++11 [expr.prim.lambda]p10: |
| // The identifiers in a capture-list are looked up using the usual rules |
| // for unqualified name lookup (3.4.1); each such lookup shall find a |
| // variable with automatic storage duration declared in the reaching |
| // scope of the local lambda expression. |
| // FIXME: Check reaching scope. |
| VarDecl *Var = R.getAsSingle<VarDecl>(); |
| if (!Var) { |
| Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id; |
| continue; |
| } |
| |
| if (!Var->hasLocalStorage()) { |
| Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id; |
| Diag(Var->getLocation(), diag::note_previous_decl) << C->Id; |
| continue; |
| } |
| |
| // C++11 [expr.prim.lambda]p8: |
| // An identifier or this shall not appear more than once in a |
| // lambda-capture. |
| if (LSI->isCaptured(Var)) { |
| Diag(C->Loc, diag::err_capture_more_than_once) |
| << C->Id |
| << SourceRange(LSI->getCapture(Var).getLocation()) |
| << FixItHint::CreateRemoval( |
| SourceRange(PP.getLocForEndOfToken(PrevCaptureLoc), C->Loc)); |
| continue; |
| } |
| |
| TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef : |
| TryCapture_ExplicitByVal; |
| TryCaptureVar(Var, C->Loc, Kind); |
| } |
| LSI->finishedExplicitCaptures(); |
| |
| // Set the parameters on the decl, if specified. |
| if (isa<FunctionProtoTypeLoc>(MethodTyInfo->getTypeLoc())) { |
| FunctionProtoTypeLoc Proto = |
| cast<FunctionProtoTypeLoc>(MethodTyInfo->getTypeLoc()); |
| Method->setParams(Proto.getParams()); |
| CheckParmsForFunctionDef(Method->param_begin(), |
| Method->param_end(), |
| /*CheckParameterNames=*/false); |
| |
| // Introduce our parameters into the function scope |
| for (unsigned p = 0, NumParams = Method->getNumParams(); p < NumParams; ++p) { |
| ParmVarDecl *Param = Method->getParamDecl(p); |
| Param->setOwningFunction(Method); |
| |
| // If this has an identifier, add it to the scope stack. |
| if (Param->getIdentifier()) { |
| CheckShadow(CurScope, Param); |
| |
| PushOnScopeChains(Param, CurScope); |
| } |
| } |
| } |
| |
| const FunctionType *Fn = MethodTy->getAs<FunctionType>(); |
| QualType RetTy = Fn->getResultType(); |
| if (RetTy != Context.DependentTy) { |
| LSI->ReturnType = RetTy; |
| } else { |
| LSI->HasImplicitReturnType = true; |
| } |
| |
| // FIXME: Check return type is complete, !isObjCObjectType |
| |
| // Enter a new evaluation context to insulate the block from any |
| // cleanups from the enclosing full-expression. |
| PushExpressionEvaluationContext(PotentiallyEvaluated); |
| } |
| |
| void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope) { |
| // Leave the expression-evaluation context. |
| DiscardCleanupsInEvaluationContext(); |
| PopExpressionEvaluationContext(); |
| |
| // Leave the context of the lambda. |
| PopDeclContext(); |
| |
| // Finalize the lambda. |
| LambdaScopeInfo *LSI = getCurLambda(); |
| CXXRecordDecl *Class = LSI->Lambda; |
| Class->setInvalidDecl(); |
| SmallVector<Decl*, 4> Fields(Class->field_begin(), Class->field_end()); |
| ActOnFields(0, Class->getLocation(), Class, Fields, |
| SourceLocation(), SourceLocation(), 0); |
| CheckCompletedCXXClass(Class); |
| |
| PopFunctionScopeInfo(); |
| } |
| |
| ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, |
| Stmt *Body, Scope *CurScope) { |
| // Leave the expression-evaluation context. |
| DiscardCleanupsInEvaluationContext(); |
| PopExpressionEvaluationContext(); |
| |
| // Collect information from the lambda scope. |
| llvm::SmallVector<LambdaExpr::Capture, 4> Captures; |
| llvm::SmallVector<Expr *, 4> CaptureInits; |
| LambdaCaptureDefault CaptureDefault; |
| CXXRecordDecl *Class; |
| CXXMethodDecl *CallOperator; |
| SourceRange IntroducerRange; |
| bool ExplicitParams; |
| bool LambdaExprNeedsCleanups; |
| { |
| LambdaScopeInfo *LSI = getCurLambda(); |
| CallOperator = LSI->CallOperator; |
| Class = LSI->Lambda; |
| IntroducerRange = LSI->IntroducerRange; |
| ExplicitParams = LSI->ExplicitParams; |
| LambdaExprNeedsCleanups = LSI->ExprNeedsCleanups; |
| |
| // Translate captures. |
| for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I) { |
| LambdaScopeInfo::Capture From = LSI->Captures[I]; |
| assert(!From.isBlockCapture() && "Cannot capture __block variables"); |
| bool IsImplicit = I >= LSI->NumExplicitCaptures; |
| |
| // Handle 'this' capture. |
| if (From.isThisCapture()) { |
| Captures.push_back(LambdaExpr::Capture(From.getLocation(), |
| IsImplicit, |
| LCK_This)); |
| CaptureInits.push_back(new (Context) CXXThisExpr(From.getLocation(), |
| getCurrentThisType(), |
| /*isImplicit=*/true)); |
| continue; |
| } |
| |
| VarDecl *Var = From.getVariable(); |
| // FIXME: Handle pack expansions. |
| LambdaCaptureKind Kind = From.isCopyCapture()? LCK_ByCopy : LCK_ByRef; |
| Captures.push_back(LambdaExpr::Capture(From.getLocation(), IsImplicit, |
| Kind, Var)); |
| CaptureInits.push_back(From.getCopyExpr()); |
| } |
| |
| switch (LSI->ImpCaptureStyle) { |
| case CapturingScopeInfo::ImpCap_None: |
| CaptureDefault = LCD_None; |
| break; |
| |
| case CapturingScopeInfo::ImpCap_LambdaByval: |
| CaptureDefault = LCD_ByCopy; |
| break; |
| |
| case CapturingScopeInfo::ImpCap_LambdaByref: |
| CaptureDefault = LCD_ByRef; |
| break; |
| |
| case CapturingScopeInfo::ImpCap_Block: |
| llvm_unreachable("block capture in lambda"); |
| break; |
| } |
| |
| // C++11 [expr.prim.lambda]p4: |
| // If a lambda-expression does not include a |
| // trailing-return-type, it is as if the trailing-return-type |
| // denotes the following type: |
| // FIXME: Assumes current resolution to core issue 975. |
| if (LSI->HasImplicitReturnType) { |
| // - if there are no return statements in the |
| // compound-statement, or all return statements return |
| // either an expression of type void or no expression or |
| // braced-init-list, the type void; |
| if (LSI->ReturnType.isNull()) { |
| LSI->ReturnType = Context.VoidTy; |
| } else { |
| // C++11 [expr.prim.lambda]p4: |
| // - if the compound-statement is of the form |
| // |
| // { attribute-specifier-seq[opt] return expression ; } |
| // |
| // the type of the returned expression after |
| // lvalue-to-rvalue conversion (4.1), array-to-pointer |
| // conver- sion (4.2), and function-to-pointer conversion |
| // (4.3); |
| // |
| // Since we're accepting the resolution to a post-C++11 core |
| // issue with a non-trivial extension, provide a warning (by |
| // default). |
| CompoundStmt *CompoundBody = cast<CompoundStmt>(Body); |
| if (!(CompoundBody->size() == 1 && |
| isa<ReturnStmt>(*CompoundBody->body_begin())) && |
| !Context.hasSameType(LSI->ReturnType, Context.VoidTy)) |
| Diag(IntroducerRange.getBegin(), |
| diag::ext_lambda_implies_void_return); |
| } |
| |
| // Create a function type with the inferred return type. |
| const FunctionProtoType *Proto |
| = CallOperator->getType()->getAs<FunctionProtoType>(); |
| QualType FunctionTy |
| = Context.getFunctionType(LSI->ReturnType, |
| Proto->arg_type_begin(), |
| Proto->getNumArgs(), |
| Proto->getExtProtoInfo()); |
| CallOperator->setType(FunctionTy); |
| } |
| |
| // C++ [expr.prim.lambda]p7: |
| // The lambda-expression's compound-statement yields the |
| // function-body (8.4) of the function call operator [...]. |
| ActOnFinishFunctionBody(CallOperator, Body, /*IsInstantation=*/false); |
| CallOperator->setLexicalDeclContext(Class); |
| Class->addDecl(CallOperator); |
| |
| // C++11 [expr.prim.lambda]p6: |
| // The closure type for a lambda-expression with no lambda-capture |
| // has a public non-virtual non-explicit const conversion function |
| // to pointer to function having the same parameter and return |
| // types as the closure type's function call operator. |
| if (Captures.empty() && CaptureDefault == LCD_None) { |
| const FunctionProtoType *Proto |
| = CallOperator->getType()->getAs<FunctionProtoType>(); |
| QualType FunctionPtrTy; |
| { |
| FunctionProtoType::ExtProtoInfo ExtInfo = Proto->getExtProtoInfo(); |
| ExtInfo.TypeQuals = 0; |
| QualType FunctionTy |
| = Context.getFunctionType(Proto->getResultType(), |
| Proto->arg_type_begin(), |
| Proto->getNumArgs(), |
| ExtInfo); |
| FunctionPtrTy = Context.getPointerType(FunctionTy); |
| } |
| |
| FunctionProtoType::ExtProtoInfo ExtInfo; |
| ExtInfo.TypeQuals = Qualifiers::Const; |
| QualType ConvTy = Context.getFunctionType(FunctionPtrTy, 0, 0, ExtInfo); |
| |
| SourceLocation Loc = IntroducerRange.getBegin(); |
| DeclarationName Name |
| = Context.DeclarationNames.getCXXConversionFunctionName( |
| Context.getCanonicalType(FunctionPtrTy)); |
| DeclarationNameLoc NameLoc; |
| NameLoc.NamedType.TInfo = Context.getTrivialTypeSourceInfo(FunctionPtrTy, |
| Loc); |
| CXXConversionDecl *Conversion |
| = CXXConversionDecl::Create(Context, Class, Loc, |
| DeclarationNameInfo(Name, Loc, NameLoc), |
| ConvTy, |
| Context.getTrivialTypeSourceInfo(ConvTy, |
| Loc), |
| /*isInline=*/false, /*isExplicit=*/false, |
| /*isConstexpr=*/false, Body->getLocEnd()); |
| Conversion->setAccess(AS_public); |
| Conversion->setImplicit(true); |
| Class->addDecl(Conversion); |
| } |
| |
| // Finalize the lambda class. |
| SmallVector<Decl*, 4> Fields(Class->field_begin(), Class->field_end()); |
| ActOnFields(0, Class->getLocation(), Class, Fields, |
| SourceLocation(), SourceLocation(), 0); |
| CheckCompletedCXXClass(Class); |
| |
| } |
| |
| if (LambdaExprNeedsCleanups) |
| ExprNeedsCleanups = true; |
| |
| LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange, |
| CaptureDefault, Captures, |
| ExplicitParams, CaptureInits, |
| Body->getLocEnd()); |
| Class->setLambda(Lambda); |
| |
| // C++11 [expr.prim.lambda]p2: |
| // A lambda-expression shall not appear in an unevaluated operand |
| // (Clause 5). |
| switch (ExprEvalContexts.back().Context) { |
| case Unevaluated: |
| // We don't actually diagnose this case immediately, because we |
| // could be within a context where we might find out later that |
| // the expression is potentially evaluated (e.g., for typeid). |
| ExprEvalContexts.back().Lambdas.push_back(Lambda); |
| break; |
| |
| case ConstantEvaluated: |
| case PotentiallyEvaluated: |
| case PotentiallyEvaluatedIfUsed: |
| break; |
| } |
| |
| return MaybeBindToTemporary(Lambda); |
| } |
