ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
Scope *CurScope,
bool IsInstantiation) {
// 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 ExplicitResultType;
bool LambdaExprNeedsCleanups;
bool ContainsUnexpandedParameterPack;
llvm::SmallVector<VarDecl *, 4> ArrayIndexVars;
llvm::SmallVector<unsigned, 4> ArrayIndexStarts;
{
LambdaScopeInfo *LSI = getCurLambda();
CallOperator = LSI->CallOperator;
Class = LSI->Lambda;
IntroducerRange = LSI->IntroducerRange;
ExplicitParams = LSI->ExplicitParams;
ExplicitResultType = !LSI->HasImplicitReturnType;
LambdaExprNeedsCleanups = LSI->ExprNeedsCleanups;
ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
ArrayIndexVars.swap(LSI->ArrayIndexVars);
ArrayIndexStarts.swap(LSI->ArrayIndexStarts);
// 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();
LambdaCaptureKind Kind = From.isCopyCapture()? LCK_ByCopy : LCK_ByRef;
Captures.push_back(LambdaExpr::Capture(From.getLocation(), IsImplicit,
Kind, Var, From.getEllipsisLoc()));
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) {
deduceClosureReturnType(*LSI);
// - 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;
}
// 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, IsInstantiation);
CallOperator->setLexicalDeclContext(Class);
Class->addDecl(CallOperator);
PopExpressionEvaluationContext();
// 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)
addFunctionPointerConversion(*this, IntroducerRange, Class,
CallOperator);
// Objective-C++:
// The closure type for a lambda-expression has a public non-virtual
// non-explicit const conversion function to a block pointer having the
// same parameter and return types as the closure type's function call
// operator.
if (getLangOpts().Blocks && getLangOpts().ObjC1)
addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
// Finalize the lambda class.
SmallVector<Decl*, 4> Fields;
for (RecordDecl::field_iterator i = Class->field_begin(),
e = Class->field_end(); i != e; ++i)
Fields.push_back(*i);
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, ExplicitResultType,
CaptureInits, ArrayIndexVars,
ArrayIndexStarts, Body->getLocEnd(),
ContainsUnexpandedParameterPack);
// C++11 [expr.prim.lambda]p2:
// A lambda-expression shall not appear in an unevaluated operand
// (Clause 5).
if (!CurContext->isDependentContext()) {
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);
}
ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
Scope *CurScope,
llvm::Optional<unsigned> ManglingNumber,
Decl *ContextDecl,
bool IsInstantiation) {
// 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 ExplicitResultType;
bool LambdaExprNeedsCleanups;
llvm::SmallVector<VarDecl *, 4> ArrayIndexVars;
llvm::SmallVector<unsigned, 4> ArrayIndexStarts;
{
LambdaScopeInfo *LSI = getCurLambda();
CallOperator = LSI->CallOperator;
Class = LSI->Lambda;
IntroducerRange = LSI->IntroducerRange;
ExplicitParams = LSI->ExplicitParams;
ExplicitResultType = !LSI->HasImplicitReturnType;
LambdaExprNeedsCleanups = LSI->ExprNeedsCleanups;
ArrayIndexVars.swap(LSI->ArrayIndexVars);
ArrayIndexStarts.swap(LSI->ArrayIndexStarts);
// 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();
LambdaCaptureKind Kind = From.isCopyCapture()? LCK_ByCopy : LCK_ByRef;
Captures.push_back(LambdaExpr::Capture(From.getLocation(), IsImplicit,
Kind, Var, From.getEllipsisLoc()));
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, IsInstantiation);
CallOperator->setLexicalDeclContext(Class);
Class->addDecl(CallOperator);
PopExpressionEvaluationContext();
// 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)
addFunctionPointerConversion(*this, IntroducerRange, Class,
CallOperator);
// Objective-C++:
// The closure type for a lambda-expression has a public non-virtual
// non-explicit const conversion function to a block pointer having the
// same parameter and return types as the closure type's function call
// operator.
if (getLangOpts().Blocks && getLangOpts().ObjC1)
addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
// 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;
// If we don't already have a mangling number for this lambda expression,
// allocate one now.
if (!ManglingNumber) {
ContextDecl = ExprEvalContexts.back().LambdaContextDecl;
enum ContextKind {
Normal,
DefaultArgument,
DataMember,
StaticDataMember
} Kind = Normal;
// Default arguments of member function parameters that appear in a class
// definition, as well as the initializers of data members, receive special
// treatment. Identify them.
if (ContextDecl) {
if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(ContextDecl)) {
if (const DeclContext *LexicalDC
= Param->getDeclContext()->getLexicalParent())
if (LexicalDC->isRecord())
Kind = DefaultArgument;
} else if (VarDecl *Var = dyn_cast<VarDecl>(ContextDecl)) {
if (Var->getDeclContext()->isRecord())
Kind = StaticDataMember;
} else if (isa<FieldDecl>(ContextDecl)) {
Kind = DataMember;
}
}
switch (Kind) {
case Normal:
if (CurContext->isDependentContext() || isInInlineFunction(CurContext))
ManglingNumber = Context.getLambdaManglingNumber(CallOperator);
else
ManglingNumber = 0;
// There is no special context for this lambda.
ContextDecl = 0;
break;
case StaticDataMember:
if (!CurContext->isDependentContext()) {
ManglingNumber = 0;
ContextDecl = 0;
break;
}
// Fall through to assign a mangling number.
case DataMember:
case DefaultArgument:
ManglingNumber = ExprEvalContexts.back().getLambdaMangleContext()
.getManglingNumber(CallOperator);
break;
}
}
LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange,
CaptureDefault, Captures,
ExplicitParams, ExplicitResultType,
CaptureInits, ArrayIndexVars,
ArrayIndexStarts, Body->getLocEnd(),
*ManglingNumber, ContextDecl);
// C++11 [expr.prim.lambda]p2:
// A lambda-expression shall not appear in an unevaluated operand
// (Clause 5).
if (!CurContext->isDependentContext()) {
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);
}