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llvm / llvm-project / clang / refs/heads/master / . / lib / Sema / SemaLambda.cpp
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//===--- SemaLambda.cpp - Semantic Analysis for C++11 Lambdas -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for C++ lambda expressions.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/SemaLambda.h"
#include "TypeLocBuilder.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/MangleNumberingContext.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaARM.h"
#include "clang/Sema/SemaCUDA.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/SemaOpenMP.h"
#include "clang/Sema/SemaSYCL.h"
#include "clang/Sema/Template.h"
#include "llvm/ADT/STLExtras.h"
#include <optional>
using namespace clang;
using namespace sema;
/// Examines the FunctionScopeInfo stack to determine the nearest
/// enclosing lambda (to the current lambda) that is 'capture-ready' for
/// the variable referenced in the current lambda (i.e. \p VarToCapture).
/// If successful, returns the index into Sema's FunctionScopeInfo stack
/// of the capture-ready lambda's LambdaScopeInfo.
///
/// Climbs down the stack of lambdas (deepest nested lambda - i.e. current
/// lambda - is on top) to determine the index of the nearest enclosing/outer
/// lambda that is ready to capture the \p VarToCapture being referenced in
/// the current lambda.
/// As we climb down the stack, we want the index of the first such lambda -
/// that is the lambda with the highest index that is 'capture-ready'.
///
/// A lambda 'L' is capture-ready for 'V' (var or this) if:
/// - its enclosing context is non-dependent
/// - and if the chain of lambdas between L and the lambda in which
/// V is potentially used (i.e. the lambda at the top of the scope info
/// stack), can all capture or have already captured V.
/// If \p VarToCapture is 'null' then we are trying to capture 'this'.
///
/// Note that a lambda that is deemed 'capture-ready' still needs to be checked
/// for whether it is 'capture-capable' (see
/// getStackIndexOfNearestEnclosingCaptureCapableLambda), before it can truly
/// capture.
///
/// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
/// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
/// is at the top of the stack and has the highest index.
/// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
///
/// \returns An UnsignedOrNone Index that if evaluates to 'true'
/// contains the index (into Sema's FunctionScopeInfo stack) of the innermost
/// lambda which is capture-ready. If the return value evaluates to 'false'
/// then no lambda is capture-ready for \p VarToCapture.
static inline UnsignedOrNone getStackIndexOfNearestEnclosingCaptureReadyLambda(
ArrayRef<const clang::sema::FunctionScopeInfo *> FunctionScopes,
ValueDecl *VarToCapture) {
// Label failure to capture.
const UnsignedOrNone NoLambdaIsCaptureReady = std::nullopt;
// Ignore all inner captured regions.
unsigned CurScopeIndex = FunctionScopes.size() - 1;
while (CurScopeIndex > 0 && isa<clang::sema::CapturedRegionScopeInfo>(
FunctionScopes[CurScopeIndex]))
--CurScopeIndex;
assert(
isa<clang::sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]) &&
"The function on the top of sema's function-info stack must be a lambda");
// If VarToCapture is null, we are attempting to capture 'this'.
const bool IsCapturingThis = !VarToCapture;
const bool IsCapturingVariable = !IsCapturingThis;
// Start with the current lambda at the top of the stack (highest index).
DeclContext *EnclosingDC =
cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex])->CallOperator;
do {
const clang::sema::LambdaScopeInfo *LSI =
cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]);
// IF we have climbed down to an intervening enclosing lambda that contains
// the variable declaration - it obviously can/must not capture the
// variable.
// Since its enclosing DC is dependent, all the lambdas between it and the
// innermost nested lambda are dependent (otherwise we wouldn't have
// arrived here) - so we don't yet have a lambda that can capture the
// variable.
if (IsCapturingVariable &&
VarToCapture->getDeclContext()->Equals(EnclosingDC))
return NoLambdaIsCaptureReady;
// For an enclosing lambda to be capture ready for an entity, all
// intervening lambda's have to be able to capture that entity. If even
// one of the intervening lambda's is not capable of capturing the entity
// then no enclosing lambda can ever capture that entity.
// For e.g.
// const int x = 10;
// [=](auto a) { #1
// [](auto b) { #2 <-- an intervening lambda that can never capture 'x'
// [=](auto c) { #3
// f(x, c); <-- can not lead to x's speculative capture by #1 or #2
// }; }; };
// If they do not have a default implicit capture, check to see
// if the entity has already been explicitly captured.
// If even a single dependent enclosing lambda lacks the capability
// to ever capture this variable, there is no further enclosing
// non-dependent lambda that can capture this variable.
if (LSI->ImpCaptureStyle == sema::LambdaScopeInfo::ImpCap_None) {
if (IsCapturingVariable && !LSI->isCaptured(VarToCapture))
return NoLambdaIsCaptureReady;
if (IsCapturingThis && !LSI->isCXXThisCaptured())
return NoLambdaIsCaptureReady;
}
EnclosingDC = getLambdaAwareParentOfDeclContext(EnclosingDC);
assert(CurScopeIndex);
--CurScopeIndex;
} while (!EnclosingDC->isTranslationUnit() &&
EnclosingDC->isDependentContext() &&
isLambdaCallOperator(EnclosingDC));
assert(CurScopeIndex < (FunctionScopes.size() - 1));
// If the enclosingDC is not dependent, then the immediately nested lambda
// (one index above) is capture-ready.
if (!EnclosingDC->isDependentContext())
return CurScopeIndex + 1;
return NoLambdaIsCaptureReady;
}
/// Examines the FunctionScopeInfo stack to determine the nearest
/// enclosing lambda (to the current lambda) that is 'capture-capable' for
/// the variable referenced in the current lambda (i.e. \p VarToCapture).
/// If successful, returns the index into Sema's FunctionScopeInfo stack
/// of the capture-capable lambda's LambdaScopeInfo.
///
/// Given the current stack of lambdas being processed by Sema and
/// the variable of interest, to identify the nearest enclosing lambda (to the
/// current lambda at the top of the stack) that can truly capture
/// a variable, it has to have the following two properties:
/// a) 'capture-ready' - be the innermost lambda that is 'capture-ready':
/// - climb down the stack (i.e. starting from the innermost and examining
/// each outer lambda step by step) checking if each enclosing
/// lambda can either implicitly or explicitly capture the variable.
/// Record the first such lambda that is enclosed in a non-dependent
/// context. If no such lambda currently exists return failure.
/// b) 'capture-capable' - make sure the 'capture-ready' lambda can truly
/// capture the variable by checking all its enclosing lambdas:
/// - check if all outer lambdas enclosing the 'capture-ready' lambda
/// identified above in 'a' can also capture the variable (this is done
/// via tryCaptureVariable for variables and CheckCXXThisCapture for
/// 'this' by passing in the index of the Lambda identified in step 'a')
///
/// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
/// LambdaScopeInfo inherits from). The current/deepest/innermost lambda
/// is at the top of the stack.
///
/// \param VarToCapture - the variable to capture. If NULL, capture 'this'.
///
///
/// \returns An UnsignedOrNone Index that if evaluates to 'true'
/// contains the index (into Sema's FunctionScopeInfo stack) of the innermost
/// lambda which is capture-capable. If the return value evaluates to 'false'
/// then no lambda is capture-capable for \p VarToCapture.
UnsignedOrNone clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
ValueDecl *VarToCapture, Sema &S) {
const UnsignedOrNone NoLambdaIsCaptureCapable = std::nullopt;
const UnsignedOrNone OptionalStackIndex =
getStackIndexOfNearestEnclosingCaptureReadyLambda(FunctionScopes,
VarToCapture);
if (!OptionalStackIndex)
return NoLambdaIsCaptureCapable;
const unsigned IndexOfCaptureReadyLambda = *OptionalStackIndex;
assert(((IndexOfCaptureReadyLambda != (FunctionScopes.size() - 1)) ||
S.getCurGenericLambda()) &&
"The capture ready lambda for a potential capture can only be the "
"current lambda if it is a generic lambda");
const sema::LambdaScopeInfo *const CaptureReadyLambdaLSI =
cast<sema::LambdaScopeInfo>(FunctionScopes[IndexOfCaptureReadyLambda]);
// If VarToCapture is null, we are attempting to capture 'this'
const bool IsCapturingThis = !VarToCapture;
const bool IsCapturingVariable = !IsCapturingThis;
if (IsCapturingVariable) {
// Check if the capture-ready lambda can truly capture the variable, by
// checking whether all enclosing lambdas of the capture-ready lambda allow
// the capture - i.e. make sure it is capture-capable.
QualType CaptureType, DeclRefType;
const bool CanCaptureVariable = !S.tryCaptureVariable(
VarToCapture,
/*ExprVarIsUsedInLoc*/ SourceLocation(), TryCaptureKind::Implicit,
/*EllipsisLoc*/ SourceLocation(),
/*BuildAndDiagnose*/ false, CaptureType, DeclRefType,
&IndexOfCaptureReadyLambda);
if (!CanCaptureVariable)
return NoLambdaIsCaptureCapable;
} else {
// Check if the capture-ready lambda can truly capture 'this' by checking
// whether all enclosing lambdas of the capture-ready lambda can capture
// 'this'.
const bool CanCaptureThis =
!S.CheckCXXThisCapture(
CaptureReadyLambdaLSI->PotentialThisCaptureLocation,
/*Explicit*/ false, /*BuildAndDiagnose*/ false,
&IndexOfCaptureReadyLambda);
if (!CanCaptureThis)
return NoLambdaIsCaptureCapable;
}
return IndexOfCaptureReadyLambda;
}
static inline TemplateParameterList *
getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) {
if (!LSI->GLTemplateParameterList && !LSI->TemplateParams.empty()) {
LSI->GLTemplateParameterList = TemplateParameterList::Create(
SemaRef.Context,
/*Template kw loc*/ SourceLocation(),
/*L angle loc*/ LSI->ExplicitTemplateParamsRange.getBegin(),
LSI->TemplateParams,
/*R angle loc*/LSI->ExplicitTemplateParamsRange.getEnd(),
LSI->RequiresClause.get());
}
return LSI->GLTemplateParameterList;
}
CXXRecordDecl *
Sema::createLambdaClosureType(SourceRange IntroducerRange, TypeSourceInfo *Info,
unsigned LambdaDependencyKind,
LambdaCaptureDefault CaptureDefault) {
DeclContext *DC = CurContext;
bool IsGenericLambda =
Info && getGenericLambdaTemplateParameterList(getCurLambda(), *this);
// Start constructing the lambda class.
CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(
Context, DC, Info, IntroducerRange.getBegin(), LambdaDependencyKind,
IsGenericLambda, CaptureDefault);
DC->addDecl(Class);
return Class;
}
/// Determine whether the given context is or is enclosed in an inline
/// function.
static bool isInInlineFunction(const DeclContext *DC) {
while (!DC->isFileContext()) {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
if (FD->isInlined())
return true;
DC = DC->getLexicalParent();
}
return false;
}
std::tuple<MangleNumberingContext *, Decl *>
Sema::getCurrentMangleNumberContext(const DeclContext *DC) {
// Compute the context for allocating mangling numbers in the current
// expression, if the ABI requires them.
Decl *ManglingContextDecl = ExprEvalContexts.back().ManglingContextDecl;
enum ContextKind {
Normal,
DefaultArgument,
DataMember,
InlineVariable,
TemplatedVariable,
Concept,
NonInlineInModulePurview
} Kind = Normal;
bool IsInNonspecializedTemplate =
inTemplateInstantiation() || CurContext->isDependentContext();
// 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.
Kind = [&]() {
if (!ManglingContextDecl)
return Normal;
if (auto *ND = dyn_cast<NamedDecl>(ManglingContextDecl)) {
// See discussion in https://github.com/itanium-cxx-abi/cxx-abi/issues/186
//
// zygoloid:
// Yeah, I think the only cases left where lambdas don't need a
// mangling are when they have (effectively) internal linkage or appear
// in a non-inline function in a non-module translation unit.
Module *M = ManglingContextDecl->getOwningModule();
if (M && M->getTopLevelModule()->isNamedModuleUnit() &&
ND->isExternallyVisible())
return NonInlineInModulePurview;
}
if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(ManglingContextDecl)) {
if (const DeclContext *LexicalDC
= Param->getDeclContext()->getLexicalParent())
if (LexicalDC->isRecord())
return DefaultArgument;
} else if (VarDecl *Var = dyn_cast<VarDecl>(ManglingContextDecl)) {
if (Var->getMostRecentDecl()->isInline())
return InlineVariable;
if (Var->getDeclContext()->isRecord() && IsInNonspecializedTemplate)
return TemplatedVariable;
if (Var->getDescribedVarTemplate())
return TemplatedVariable;
if (auto *VTS = dyn_cast<VarTemplateSpecializationDecl>(Var)) {
if (!VTS->isExplicitSpecialization())
return TemplatedVariable;
}
} else if (isa<FieldDecl>(ManglingContextDecl)) {
return DataMember;
} else if (isa<ImplicitConceptSpecializationDecl>(ManglingContextDecl)) {
return Concept;
}
return Normal;
}();
// Itanium ABI [5.1.7]:
// In the following contexts [...] the one-definition rule requires closure
// types in different translation units to "correspond":
switch (Kind) {
case Normal: {
// -- the bodies of inline or templated functions
if ((IsInNonspecializedTemplate &&
!(ManglingContextDecl && isa<ParmVarDecl>(ManglingContextDecl))) ||
isInInlineFunction(CurContext)) {
while (auto *CD = dyn_cast<CapturedDecl>(DC))
DC = CD->getParent();
return std::make_tuple(&Context.getManglingNumberContext(DC), nullptr);
}
return std::make_tuple(nullptr, nullptr);
}
case NonInlineInModulePurview:
case Concept:
// Concept definitions aren't code generated and thus aren't mangled,
// however the ManglingContextDecl is important for the purposes of
// re-forming the template argument list of the lambda for constraint
// evaluation.
case DataMember:
// -- default member initializers
case DefaultArgument:
// -- default arguments appearing in class definitions
case InlineVariable:
case TemplatedVariable:
// -- the initializers of inline or templated variables
return std::make_tuple(
&Context.getManglingNumberContext(ASTContext::NeedExtraManglingDecl,
ManglingContextDecl),
ManglingContextDecl);
}
llvm_unreachable("unexpected context");
}
static QualType
buildTypeForLambdaCallOperator(Sema &S, clang::CXXRecordDecl *Class,
TemplateParameterList *TemplateParams,
TypeSourceInfo *MethodTypeInfo) {
assert(MethodTypeInfo && "expected a non null type");
QualType MethodType = MethodTypeInfo->getType();
// If a lambda appears in a dependent context or is a generic lambda (has
// template parameters) and has an 'auto' return type, deduce it to a
// dependent type.
if (Class->isDependentContext() || TemplateParams) {
const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
QualType Result = FPT->getReturnType();
if (Result->isUndeducedType()) {
Result = S.SubstAutoTypeDependent(Result);
MethodType = S.Context.getFunctionType(Result, FPT->getParamTypes(),
FPT->getExtProtoInfo());
}
}
return MethodType;
}
// [C++2b] [expr.prim.lambda.closure] p4
// Given a lambda with a lambda-capture, the type of the explicit object
// parameter, if any, of the lambda's function call operator (possibly
// instantiated from a function call operator template) shall be either:
// - the closure type,
// - class type publicly and unambiguously derived from the closure type, or
// - a reference to a possibly cv-qualified such type.
bool Sema::DiagnoseInvalidExplicitObjectParameterInLambda(
CXXMethodDecl *Method, SourceLocation CallLoc) {
if (!isLambdaCallWithExplicitObjectParameter(Method))
return false;
CXXRecordDecl *RD = Method->getParent();
if (Method->getType()->isDependentType())
return false;
if (RD->isCapturelessLambda())
return false;
ParmVarDecl *Param = Method->getParamDecl(0);
QualType ExplicitObjectParameterType = Param->getType()
.getNonReferenceType()
.getUnqualifiedType()
.getDesugaredType(getASTContext());
CanQualType LambdaType = getASTContext().getCanonicalTagType(RD);
if (LambdaType == ExplicitObjectParameterType)
return false;
// Don't check the same instantiation twice.
//
// If this call operator is ill-formed, there is no point in issuing
// a diagnostic every time it is called because the problem is in the
// definition of the derived type, not at the call site.
//
// FIXME: Move this check to where we instantiate the method? This should
// be possible, but the naive approach of just marking the method as invalid
// leads to us emitting more diagnostics than we should have to for this case
// (1 error here *and* 1 error about there being no matching overload at the
// call site). It might be possible to avoid that by also checking if there
// is an empty cast path for the method stored in the context (signalling that
// we've already diagnosed it) and then just not building the call, but that
// doesn't really seem any simpler than diagnosing it at the call site...
auto [It, Inserted] = Context.LambdaCastPaths.try_emplace(Method);
if (!Inserted)
return It->second.empty();
CXXCastPath &Path = It->second;
CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
/*DetectVirtual=*/false);
if (!IsDerivedFrom(RD->getLocation(), ExplicitObjectParameterType, LambdaType,
Paths)) {
Diag(Param->getLocation(), diag::err_invalid_explicit_object_type_in_lambda)
<< ExplicitObjectParameterType;
return true;
}
if (Paths.isAmbiguous(LambdaType)) {
std::string PathsDisplay = getAmbiguousPathsDisplayString(Paths);
Diag(CallLoc, diag::err_explicit_object_lambda_ambiguous_base)
<< LambdaType << PathsDisplay;
return true;
}
if (CheckBaseClassAccess(CallLoc, LambdaType, ExplicitObjectParameterType,
Paths.front(),
diag::err_explicit_object_lambda_inaccessible_base))
return true;
BuildBasePathArray(Paths, Path);
return false;
}
void Sema::handleLambdaNumbering(
CXXRecordDecl *Class, CXXMethodDecl *Method,
std::optional<CXXRecordDecl::LambdaNumbering> NumberingOverride) {
if (NumberingOverride) {
Class->setLambdaNumbering(*NumberingOverride);
return;
}
ContextRAII ManglingContext(*this, Class->getDeclContext());
auto getMangleNumberingContext =
[this](CXXRecordDecl *Class,
Decl *ManglingContextDecl) -> MangleNumberingContext * {
// Get mangle numbering context if there's any extra decl context.
if (ManglingContextDecl)
return &Context.getManglingNumberContext(
ASTContext::NeedExtraManglingDecl, ManglingContextDecl);
// Otherwise, from that lambda's decl context.
auto DC = Class->getDeclContext();
while (auto *CD = dyn_cast<CapturedDecl>(DC))
DC = CD->getParent();
return &Context.getManglingNumberContext(DC);
};
CXXRecordDecl::LambdaNumbering Numbering;
MangleNumberingContext *MCtx;
std::tie(MCtx, Numbering.ContextDecl) =
getCurrentMangleNumberContext(Class->getDeclContext());
if (!MCtx && (getLangOpts().CUDA || getLangOpts().SYCLIsDevice ||
getLangOpts().SYCLIsHost)) {
// Force lambda numbering in CUDA/HIP as we need to name lambdas following
// ODR. Both device- and host-compilation need to have a consistent naming
// on kernel functions. As lambdas are potential part of these `__global__`
// function names, they needs numbering following ODR.
// Also force for SYCL, since we need this for the
// __builtin_sycl_unique_stable_name implementation, which depends on lambda
// mangling.
MCtx = getMangleNumberingContext(Class, Numbering.ContextDecl);
assert(MCtx && "Retrieving mangle numbering context failed!");
Numbering.HasKnownInternalLinkage = true;
}
if (MCtx) {
Numbering.IndexInContext = MCtx->getNextLambdaIndex();
Numbering.ManglingNumber = MCtx->getManglingNumber(Method);
Numbering.DeviceManglingNumber = MCtx->getDeviceManglingNumber(Method);
Class->setLambdaNumbering(Numbering);
if (auto *Source =
dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
Source->AssignedLambdaNumbering(Class);
}
}
static void buildLambdaScopeReturnType(Sema &S, LambdaScopeInfo *LSI,
CXXMethodDecl *CallOperator,
bool ExplicitResultType) {
if (ExplicitResultType) {
LSI->HasImplicitReturnType = false;
LSI->ReturnType = CallOperator->getReturnType();
if (!LSI->ReturnType->isDependentType() && !LSI->ReturnType->isVoidType())
S.RequireCompleteType(CallOperator->getBeginLoc(), LSI->ReturnType,
diag::err_lambda_incomplete_result);
} else {
LSI->HasImplicitReturnType = true;
}
}
void Sema::buildLambdaScope(LambdaScopeInfo *LSI, CXXMethodDecl *CallOperator,
SourceRange IntroducerRange,
LambdaCaptureDefault CaptureDefault,
SourceLocation CaptureDefaultLoc,
bool ExplicitParams, bool Mutable) {
LSI->CallOperator = CallOperator;
CXXRecordDecl *LambdaClass = CallOperator->getParent();
LSI->Lambda = LambdaClass;
if (CaptureDefault == LCD_ByCopy)
LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
else if (CaptureDefault == LCD_ByRef)
LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
LSI->CaptureDefaultLoc = CaptureDefaultLoc;
LSI->IntroducerRange = IntroducerRange;
LSI->ExplicitParams = ExplicitParams;
LSI->Mutable = Mutable;
}
void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
LSI->finishedExplicitCaptures();
}
void Sema::ActOnLambdaExplicitTemplateParameterList(
LambdaIntroducer &Intro, SourceLocation LAngleLoc,
ArrayRef<NamedDecl *> TParams, SourceLocation RAngleLoc,
ExprResult RequiresClause) {
LambdaScopeInfo *LSI = getCurLambda();
assert(LSI && "Expected a lambda scope");
assert(LSI->NumExplicitTemplateParams == 0 &&
"Already acted on explicit template parameters");
assert(LSI->TemplateParams.empty() &&
"Explicit template parameters should come "
"before invented (auto) ones");
assert(!TParams.empty() &&
"No template parameters to act on");
LSI->TemplateParams.append(TParams.begin(), TParams.end());
LSI->NumExplicitTemplateParams = TParams.size();
LSI->ExplicitTemplateParamsRange = {LAngleLoc, RAngleLoc};
LSI->RequiresClause = RequiresClause;
}
/// If this expression is an enumerator-like expression of some type
/// T, return the type T; otherwise, return null.
///
/// Pointer comparisons on the result here should always work because
/// it's derived from either the parent of an EnumConstantDecl
/// (i.e. the definition) or the declaration returned by
/// EnumType::getDecl() (i.e. the definition).
static EnumDecl *findEnumForBlockReturn(Expr *E) {
// An expression is an enumerator-like expression of type T if,
// ignoring parens and parens-like expressions:
E = E->IgnoreParens();
// - it is an enumerator whose enum type is T or
if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
if (EnumConstantDecl *D
= dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
return cast<EnumDecl>(D->getDeclContext());
}
return nullptr;
}
// - it is a comma expression whose RHS is an enumerator-like
// expression of type T or
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
if (BO->getOpcode() == BO_Comma)
return findEnumForBlockReturn(BO->getRHS());
return nullptr;
}
// - it is a statement-expression whose value expression is an
// enumerator-like expression of type T or
if (StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
if (Expr *last = dyn_cast_or_null<Expr>(SE->getSubStmt()->body_back()))
return findEnumForBlockReturn(last);
return nullptr;
}
// - it is a ternary conditional operator (not the GNU ?:
// extension) whose second and third operands are
// enumerator-like expressions of type T or
if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
if (EnumDecl *ED = findEnumForBlockReturn(CO->getTrueExpr()))
if (ED == findEnumForBlockReturn(CO->getFalseExpr()))
return ED;
return nullptr;
}
// (implicitly:)
// - it is an implicit integral conversion applied to an
// enumerator-like expression of type T or
if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
// We can sometimes see integral conversions in valid
// enumerator-like expressions.
if (ICE->getCastKind() == CK_IntegralCast)
return findEnumForBlockReturn(ICE->getSubExpr());
// Otherwise, just rely on the type.
}
// - it is an expression of that formal enum type.
if (auto *ED = E->getType()->getAsEnumDecl())
return ED;
// Otherwise, nope.
return nullptr;
}
/// Attempt to find a type T for which the returned expression of the
/// given statement is an enumerator-like expression of that type.
static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
if (Expr *retValue = ret->getRetValue())
return findEnumForBlockReturn(retValue);
return nullptr;
}
/// Attempt to find a common type T for which all of the returned
/// expressions in a block are enumerator-like expressions of that
/// type.
static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
// Try to find one for the first return.
EnumDecl *ED = findEnumForBlockReturn(*i);
if (!ED) return nullptr;
// Check that the rest of the returns have the same enum.
for (++i; i != e; ++i) {
if (findEnumForBlockReturn(*i) != ED)
return nullptr;
}
// Never infer an anonymous enum type.
if (!ED->hasNameForLinkage()) return nullptr;
return ED;
}
/// Adjust the given return statements so that they formally return
/// the given type. It should require, at most, an IntegralCast.
static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
QualType returnType) {
for (ArrayRef<ReturnStmt*>::iterator
i = returns.begin(), e = returns.end(); i != e; ++i) {
ReturnStmt *ret = *i;
Expr *retValue = ret->getRetValue();
if (S.Context.hasSameType(retValue->getType(), returnType))
continue;
// Right now we only support integral fixup casts.
assert(returnType->isIntegralOrUnscopedEnumerationType());
assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(retValue);
Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
E = ImplicitCastExpr::Create(S.Context, returnType, CK_IntegralCast, E,
/*base path*/ nullptr, VK_PRValue,
FPOptionsOverride());
if (cleanups) {
cleanups->setSubExpr(E);
} else {
ret->setRetValue(E);
}
}
}
void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
assert(CSI.HasImplicitReturnType);
// If it was ever a placeholder, it had to been deduced to DependentTy.
assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
assert((!isa<LambdaScopeInfo>(CSI) || !getLangOpts().CPlusPlus14) &&
"lambda expressions use auto deduction in C++14 onwards");
// C++ core issue 975:
// If a lambda-expression does not include a trailing-return-type,
// it is as if the trailing-return-type denotes the following type:
// - 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;
// - otherwise, if all return statements return an expression
// and the types of the returned expressions after
// lvalue-to-rvalue conversion (4.1 [conv.lval]),
// array-to-pointer conversion (4.2 [conv.array]), and
// function-to-pointer conversion (4.3 [conv.func]) are the
// same, that common type;
// - otherwise, the program is ill-formed.
//
// C++ core issue 1048 additionally removes top-level cv-qualifiers
// from the types of returned expressions to match the C++14 auto
// deduction rules.
//
// In addition, in blocks in non-C++ modes, if all of the return
// statements are enumerator-like expressions of some type T, where
// T has a name for linkage, then we infer the return type of the
// block to be that type.
// First case: no return statements, implicit void return type.
ASTContext &Ctx = getASTContext();
if (CSI.Returns.empty()) {
// It's possible there were simply no /valid/ return statements.
// In this case, the first one we found may have at least given us a type.
if (CSI.ReturnType.isNull())
CSI.ReturnType = Ctx.VoidTy;
return;
}
// Second case: at least one return statement has dependent type.
// Delay type checking until instantiation.
assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
if (CSI.ReturnType->isDependentType())
return;
// Try to apply the enum-fuzz rule.
if (!getLangOpts().CPlusPlus) {
assert(isa<BlockScopeInfo>(CSI));
const EnumDecl *ED = findCommonEnumForBlockReturns(CSI.Returns);
if (ED) {
CSI.ReturnType = Context.getCanonicalTagType(ED);
adjustBlockReturnsToEnum(*this, CSI.Returns, CSI.ReturnType);
return;
}
}
// Third case: only one return statement. Don't bother doing extra work!
if (CSI.Returns.size() == 1)
return;
// General case: many return statements.
// Check that they all have compatible return types.
// We require the return types to strictly match here.
// Note that we've already done the required promotions as part of
// processing the return statement.
for (const ReturnStmt *RS : CSI.Returns) {
const Expr *RetE = RS->getRetValue();
QualType ReturnType =
(RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
if (Context.getCanonicalFunctionResultType(ReturnType) ==
Context.getCanonicalFunctionResultType(CSI.ReturnType)) {
// Use the return type with the strictest possible nullability annotation.
auto RetTyNullability = ReturnType->getNullability();
auto BlockNullability = CSI.ReturnType->getNullability();
if (BlockNullability &&
(!RetTyNullability ||
hasWeakerNullability(*RetTyNullability, *BlockNullability)))
CSI.ReturnType = ReturnType;
continue;
}
// FIXME: This is a poor diagnostic for ReturnStmts without expressions.
// TODO: It's possible that the *first* return is the divergent one.
Diag(RS->getBeginLoc(),
diag::err_typecheck_missing_return_type_incompatible)
<< ReturnType << CSI.ReturnType << isa<LambdaScopeInfo>(CSI);
// Continue iterating so that we keep emitting diagnostics.
}
}
QualType Sema::buildLambdaInitCaptureInitialization(
SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
UnsignedOrNone NumExpansions, IdentifierInfo *Id, bool IsDirectInit,
Expr *&Init) {
// Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
// deduce against.
QualType DeductType = Context.getAutoDeductType();
TypeLocBuilder TLB;
AutoTypeLoc TL = TLB.push<AutoTypeLoc>(DeductType);
TL.setNameLoc(Loc);
if (ByRef) {
DeductType = BuildReferenceType(DeductType, true, Loc, Id);
assert(!DeductType.isNull() && "can't build reference to auto");
TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
}
if (EllipsisLoc.isValid()) {
if (Init->containsUnexpandedParameterPack()) {
Diag(EllipsisLoc, getLangOpts().CPlusPlus20
? diag::warn_cxx17_compat_init_capture_pack
: diag::ext_init_capture_pack);
DeductType = Context.getPackExpansionType(DeductType, NumExpansions,
/*ExpectPackInType=*/false);
TLB.push<PackExpansionTypeLoc>(DeductType).setEllipsisLoc(EllipsisLoc);
} else {
// Just ignore the ellipsis for now and form a non-pack variable. We'll
// diagnose this later when we try to capture it.
}
}
TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
// Deduce the type of the init capture.
QualType DeducedType = deduceVarTypeFromInitializer(
/*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
SourceRange(Loc, Loc), IsDirectInit, Init);
if (DeducedType.isNull())
return QualType();
// Are we a non-list direct initialization?
ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
// Perform initialization analysis and ensure any implicit conversions
// (such as lvalue-to-rvalue) are enforced.
InitializedEntity Entity =
InitializedEntity::InitializeLambdaCapture(Id, DeducedType, Loc);
InitializationKind Kind =
IsDirectInit
? (CXXDirectInit ? InitializationKind::CreateDirect(
Loc, Init->getBeginLoc(), Init->getEndLoc())
: InitializationKind::CreateDirectList(Loc))
: InitializationKind::CreateCopy(Loc, Init->getBeginLoc());
MultiExprArg Args = Init;
if (CXXDirectInit)
Args =
MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
QualType DclT;
InitializationSequence InitSeq(*this, Entity, Kind, Args);
ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
if (Result.isInvalid())
return QualType();
Init = Result.getAs<Expr>();
return DeducedType;
}
VarDecl *Sema::createLambdaInitCaptureVarDecl(
SourceLocation Loc, QualType InitCaptureType, SourceLocation EllipsisLoc,
IdentifierInfo *Id, unsigned InitStyle, Expr *Init, DeclContext *DeclCtx) {
// FIXME: Retain the TypeSourceInfo from buildLambdaInitCaptureInitialization
// rather than reconstructing it here.
TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType, Loc);
if (auto PETL = TSI->getTypeLoc().getAs<PackExpansionTypeLoc>())
PETL.setEllipsisLoc(EllipsisLoc);
// Create a dummy variable representing the init-capture. This is not actually
// used as a variable, and only exists as a way to name and refer to the
// init-capture.
// FIXME: Pass in separate source locations for '&' and identifier.
VarDecl *NewVD = VarDecl::Create(Context, DeclCtx, Loc, Loc, Id,
InitCaptureType, TSI, SC_Auto);
NewVD->setInitCapture(true);
NewVD->setReferenced(true);
// FIXME: Pass in a VarDecl::InitializationStyle.
NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
NewVD->markUsed(Context);
NewVD->setInit(Init);
if (NewVD->isParameterPack())
getCurLambda()->LocalPacks.push_back(NewVD);
return NewVD;
}
void Sema::addInitCapture(LambdaScopeInfo *LSI, VarDecl *Var, bool ByRef) {
assert(Var->isInitCapture() && "init capture flag should be set");
LSI->addCapture(Var, /*isBlock=*/false, ByRef,
/*isNested=*/false, Var->getLocation(), SourceLocation(),
Var->getType(), /*Invalid=*/false);
}
// Unlike getCurLambda, getCurrentLambdaScopeUnsafe doesn't
// check that the current lambda is in a consistent or fully constructed state.
static LambdaScopeInfo *getCurrentLambdaScopeUnsafe(Sema &S) {
assert(!S.FunctionScopes.empty());
return cast<LambdaScopeInfo>(S.FunctionScopes[S.FunctionScopes.size() - 1]);
}
static TypeSourceInfo *
getDummyLambdaType(Sema &S, SourceLocation Loc = SourceLocation()) {
// 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(S.Context.getDefaultCallingConvention(
/*IsVariadic=*/false, /*IsCXXMethod=*/true));
EPI.HasTrailingReturn = true;
EPI.TypeQuals.addConst();
LangAS AS = S.getDefaultCXXMethodAddrSpace();
if (AS != LangAS::Default)
EPI.TypeQuals.addAddressSpace(AS);
// C++1y [expr.prim.lambda]:
// The lambda return type is 'auto', which is replaced by the
// trailing-return type if provided and/or deduced from 'return'
// statements
// We don't do this before C++1y, because we don't support deduced return
// types there.
QualType DefaultTypeForNoTrailingReturn = S.getLangOpts().CPlusPlus14
? S.Context.getAutoDeductType()
: S.Context.DependentTy;
QualType MethodTy =
S.Context.getFunctionType(DefaultTypeForNoTrailingReturn, {}, EPI);
return S.Context.getTrivialTypeSourceInfo(MethodTy, Loc);
}
static TypeSourceInfo *getLambdaType(Sema &S, LambdaIntroducer &Intro,
Declarator &ParamInfo, Scope *CurScope,
SourceLocation Loc,
bool &ExplicitResultType) {
ExplicitResultType = false;
assert(
(ParamInfo.getDeclSpec().getStorageClassSpec() ==
DeclSpec::SCS_unspecified ||
ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static) &&
"Unexpected storage specifier");
bool IsLambdaStatic =
ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static;
TypeSourceInfo *MethodTyInfo;
if (ParamInfo.getNumTypeObjects() == 0) {
MethodTyInfo = getDummyLambdaType(S, Loc);
} else {
// Check explicit parameters
S.CheckExplicitObjectLambda(ParamInfo);
DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
bool HasExplicitObjectParameter =
ParamInfo.isExplicitObjectMemberFunction();
ExplicitResultType = FTI.hasTrailingReturnType();
if (!FTI.hasMutableQualifier() && !IsLambdaStatic &&
!HasExplicitObjectParameter)
FTI.getOrCreateMethodQualifiers().SetTypeQual(DeclSpec::TQ_const, Loc);
if (ExplicitResultType && S.getLangOpts().HLSL) {
QualType RetTy = FTI.getTrailingReturnType().get();
if (!RetTy.isNull()) {
// HLSL does not support specifying an address space on a lambda return
// type.
LangAS AddressSpace = RetTy.getAddressSpace();
if (AddressSpace != LangAS::Default)
S.Diag(FTI.getTrailingReturnTypeLoc(),
diag::err_return_value_with_address_space);
}
}
MethodTyInfo = S.GetTypeForDeclarator(ParamInfo);
assert(MethodTyInfo && "no type from lambda-declarator");
// Check for unexpanded parameter packs in the method type.
if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
S.DiagnoseUnexpandedParameterPack(Intro.Range.getBegin(), MethodTyInfo,
S.UPPC_DeclarationType);
}
return MethodTyInfo;
}
CXXMethodDecl *Sema::CreateLambdaCallOperator(SourceRange IntroducerRange,
CXXRecordDecl *Class) {
// C++20 [expr.prim.lambda.closure]p3:
// The closure type for a lambda-expression has a public inline function
// call operator (for a non-generic lambda) or function call operator
// template (for a generic lambda) 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 =
DeclarationNameLoc::makeCXXOperatorNameLoc(IntroducerRange.getBegin());
CXXMethodDecl *Method = CXXMethodDecl::Create(
Context, Class, SourceLocation(),
DeclarationNameInfo(MethodName, IntroducerRange.getBegin(),
MethodNameLoc),
QualType(), /*Tinfo=*/nullptr, SC_None,
getCurFPFeatures().isFPConstrained(),
/*isInline=*/true, ConstexprSpecKind::Unspecified, SourceLocation(),
/*TrailingRequiresClause=*/{});
Method->setAccess(AS_public);
return Method;
}
void Sema::AddTemplateParametersToLambdaCallOperator(
CXXMethodDecl *CallOperator, CXXRecordDecl *Class,
TemplateParameterList *TemplateParams) {
assert(TemplateParams && "no template parameters");
FunctionTemplateDecl *TemplateMethod = FunctionTemplateDecl::Create(
Context, Class, CallOperator->getLocation(), CallOperator->getDeclName(),
TemplateParams, CallOperator);
TemplateMethod->setAccess(AS_public);
CallOperator->setDescribedFunctionTemplate(TemplateMethod);
}
void Sema::CompleteLambdaCallOperator(
CXXMethodDecl *Method, SourceLocation LambdaLoc,
SourceLocation CallOperatorLoc,
const AssociatedConstraint &TrailingRequiresClause,
TypeSourceInfo *MethodTyInfo, ConstexprSpecKind ConstexprKind,
StorageClass SC, ArrayRef<ParmVarDecl *> Params,
bool HasExplicitResultType) {
LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
if (TrailingRequiresClause)
Method->setTrailingRequiresClause(TrailingRequiresClause);
TemplateParameterList *TemplateParams =
getGenericLambdaTemplateParameterList(LSI, *this);
DeclContext *DC = Method->getLexicalDeclContext();
// DeclContext::addDecl() assumes that the DeclContext we're adding to is the
// lexical context of the Method. Do so.
Method->setLexicalDeclContext(LSI->Lambda);
if (TemplateParams) {
FunctionTemplateDecl *TemplateMethod =
Method->getDescribedFunctionTemplate();
assert(TemplateMethod &&
"AddTemplateParametersToLambdaCallOperator should have been called");
LSI->Lambda->addDecl(TemplateMethod);
TemplateMethod->setLexicalDeclContext(DC);
} else {
LSI->Lambda->addDecl(Method);
}
LSI->Lambda->setLambdaIsGeneric(TemplateParams);
LSI->Lambda->setLambdaTypeInfo(MethodTyInfo);
Method->setLexicalDeclContext(DC);
Method->setLocation(LambdaLoc);
Method->setInnerLocStart(CallOperatorLoc);
Method->setTypeSourceInfo(MethodTyInfo);
Method->setType(buildTypeForLambdaCallOperator(*this, LSI->Lambda,
TemplateParams, MethodTyInfo));
Method->setConstexprKind(ConstexprKind);
Method->setStorageClass(SC);
if (!Params.empty()) {
CheckParmsForFunctionDef(Params, /*CheckParameterNames=*/false);
Method->setParams(Params);
for (auto P : Method->parameters()) {
assert(P && "null in a parameter list");
P->setOwningFunction(Method);
}
}
buildLambdaScopeReturnType(*this, LSI, Method, HasExplicitResultType);
}
void Sema::ActOnLambdaExpressionAfterIntroducer(LambdaIntroducer &Intro,
Scope *CurrentScope) {
LambdaScopeInfo *LSI = getCurLambda();
assert(LSI && "LambdaScopeInfo should be on stack!");
if (Intro.Default == LCD_ByCopy)
LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
else if (Intro.Default == LCD_ByRef)
LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
LSI->CaptureDefaultLoc = Intro.DefaultLoc;
LSI->IntroducerRange = Intro.Range;
LSI->AfterParameterList = false;
assert(LSI->NumExplicitTemplateParams == 0);
// Determine if we're within a context where we know that the lambda will
// be dependent, because there are template parameters in scope.
CXXRecordDecl::LambdaDependencyKind LambdaDependencyKind =
CXXRecordDecl::LDK_Unknown;
if (CurScope->getTemplateParamParent() != nullptr) {
LambdaDependencyKind = CXXRecordDecl::LDK_AlwaysDependent;
} else if (Scope *P = CurScope->getParent()) {
// Given a lambda defined inside a requires expression,
//
// struct S {
// S(auto var) requires requires { [&] -> decltype(var) { }; }
// {}
// };
//
// The parameter var is not injected into the function Decl at the point of
// parsing lambda. In such scenarios, perceiving it as dependent could
// result in the constraint being evaluated, which matches what GCC does.
while (P->getEntity() && P->getEntity()->isRequiresExprBody())
P = P->getParent();
if (P->isFunctionDeclarationScope() &&
llvm::any_of(P->decls(), [](Decl *D) {
return isa<ParmVarDecl>(D) &&
cast<ParmVarDecl>(D)->getType()->isTemplateTypeParmType();
}))
LambdaDependencyKind = CXXRecordDecl::LDK_AlwaysDependent;
}
CXXRecordDecl *Class = createLambdaClosureType(
Intro.Range, /*Info=*/nullptr, LambdaDependencyKind, Intro.Default);
LSI->Lambda = Class;
CXXMethodDecl *Method = CreateLambdaCallOperator(Intro.Range, Class);
LSI->CallOperator = Method;
// Temporarily set the lexical declaration context to the current
// context, so that the Scope stack matches the lexical nesting.
Method->setLexicalDeclContext(CurContext);
PushDeclContext(CurScope, Method);
bool ContainsUnexpandedParameterPack = false;
// Distinct capture names, for diagnostics.
llvm::DenseMap<IdentifierInfo *, ValueDecl *> CaptureNames;
// Handle explicit captures.
SourceLocation PrevCaptureLoc =
Intro.Default == LCD_None ? Intro.Range.getBegin() : Intro.DefaultLoc;
for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
PrevCaptureLoc = C->Loc, ++C) {
if (C->Kind == LCK_This || C->Kind == LCK_StarThis) {
if (C->Kind == LCK_StarThis)
Diag(C->Loc, !getLangOpts().CPlusPlus17
? diag::ext_star_this_lambda_capture_cxx17
: diag::warn_cxx14_compat_star_this_lambda_capture);
// 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(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
continue;
}
// C++20 [expr.prim.lambda]p8:
// If a lambda-capture includes a capture-default that is =,
// each simple-capture of that lambda-capture shall be of the form
// "&identifier", "this", or "* this". [ Note: The form [&,this] is
// redundant but accepted for compatibility with ISO C++14. --end note ]
if (Intro.Default == LCD_ByCopy && C->Kind != LCK_StarThis)
Diag(C->Loc, !getLangOpts().CPlusPlus20
? diag::ext_equals_this_lambda_capture_cxx20
: diag::warn_cxx17_compat_equals_this_lambda_capture);
// 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, /*BuildAndDiagnose*/ true,
/*FunctionScopeIndexToStopAtPtr*/ nullptr,
C->Kind == LCK_StarThis);
if (!LSI->Captures.empty())
LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
continue;
}
assert(C->Id && "missing identifier for capture");
if (C->Init.isInvalid())
continue;
ValueDecl *Var = nullptr;
if (C->Init.isUsable()) {
Diag(C->Loc, getLangOpts().CPlusPlus14
? diag::warn_cxx11_compat_init_capture
: diag::ext_init_capture);
// If the initializer expression is usable, but the InitCaptureType
// is not, then an error has occurred - so ignore the capture for now.
// for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
// FIXME: we should create the init capture variable and mark it invalid
// in this case.
if (C->InitCaptureType.get().isNull())
continue;
if (C->Init.get()->containsUnexpandedParameterPack() &&
!C->InitCaptureType.get()->getAs<PackExpansionType>())
DiagnoseUnexpandedParameterPack(C->Init.get(), UPPC_Initializer);
unsigned InitStyle;
switch (C->InitKind) {
case LambdaCaptureInitKind::NoInit:
llvm_unreachable("not an init-capture?");
case LambdaCaptureInitKind::CopyInit:
InitStyle = VarDecl::CInit;
break;
case LambdaCaptureInitKind::DirectInit:
InitStyle = VarDecl::CallInit;
break;
case LambdaCaptureInitKind::ListInit:
InitStyle = VarDecl::ListInit;
break;
}
Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
C->EllipsisLoc, C->Id, InitStyle,
C->Init.get(), Method);
assert(Var && "createLambdaInitCaptureVarDecl returned a null VarDecl?");
if (auto *V = dyn_cast<VarDecl>(Var))
CheckShadow(CurrentScope, V);
PushOnScopeChains(Var, CurrentScope, false);
} else {
assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
"init capture has valid but null init?");
// 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(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(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
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)
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;
}
if (auto *BD = R.getAsSingle<BindingDecl>())
Var = BD;
else if (R.getAsSingle<FieldDecl>()) {
Diag(C->Loc, diag::err_capture_class_member_does_not_name_variable)
<< C->Id;
continue;
} else
Var = R.getAsSingle<VarDecl>();
if (Var && DiagnoseUseOfDecl(Var, C->Loc))
continue;
}
// C++11 [expr.prim.lambda]p10:
// [...] each such lookup shall find a variable with automatic storage
// duration declared in the reaching scope of the local lambda expression.
// Note that the 'reaching scope' check happens in tryCaptureVariable().
if (!Var) {
Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id;
continue;
}
// C++11 [expr.prim.lambda]p8:
// An identifier or this shall not appear more than once in a
// lambda-capture.
if (auto [It, Inserted] = CaptureNames.insert(std::pair{C->Id, Var});
!Inserted) {
if (C->InitKind == LambdaCaptureInitKind::NoInit &&
!Var->isInitCapture()) {
Diag(C->Loc, diag::err_capture_more_than_once)
<< C->Id << It->second->getBeginLoc()
<< FixItHint::CreateRemoval(
SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
Var->setInvalidDecl();
} else if (Var && Var->isPlaceholderVar(getLangOpts())) {
DiagPlaceholderVariableDefinition(C->Loc);
} else {
// Previous capture captured something different (one or both was
// an init-capture): no fixit.
Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
continue;
}
}
// Ignore invalid decls; they'll just confuse the code later.
if (Var->isInvalidDecl())
continue;
VarDecl *Underlying = Var->getPotentiallyDecomposedVarDecl();
if (!Underlying->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]p23:
// A capture followed by an ellipsis is a pack expansion (14.5.3).
SourceLocation EllipsisLoc;
if (C->EllipsisLoc.isValid()) {
if (Var->isParameterPack()) {
EllipsisLoc = C->EllipsisLoc;
} else {
Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
<< (C->Init.isUsable() ? C->Init.get()->getSourceRange()
: SourceRange(C->Loc));
// Just ignore the ellipsis.
}
} else if (Var->isParameterPack()) {
ContainsUnexpandedParameterPack = true;
}
if (C->Init.isUsable()) {
addInitCapture(LSI, cast<VarDecl>(Var), C->Kind == LCK_ByRef);
} else {
TryCaptureKind Kind = C->Kind == LCK_ByRef
? TryCaptureKind::ExplicitByRef
: TryCaptureKind::ExplicitByVal;
tryCaptureVariable(Var, C->Loc, Kind, EllipsisLoc);
}
if (!LSI->Captures.empty())
LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
}
finishLambdaExplicitCaptures(LSI);
LSI->ContainsUnexpandedParameterPack |= ContainsUnexpandedParameterPack;
PopDeclContext();
}
void Sema::ActOnLambdaClosureQualifiers(LambdaIntroducer &Intro,
SourceLocation MutableLoc) {
LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
LSI->Mutable = MutableLoc.isValid();
ContextRAII Context(*this, LSI->CallOperator, /*NewThisContext*/ false);
// C++11 [expr.prim.lambda]p9:
// A lambda-expression whose smallest enclosing scope is a block scope is a
// local lambda expression; any other lambda expression shall not have a
// capture-default or simple-capture in its lambda-introducer.
//
// For simple-captures, this is covered by the check below that any named
// entity is a variable that can be captured.
//
// For DR1632, we also allow a capture-default in any context where we can
// odr-use 'this' (in particular, in a default initializer for a non-static
// data member).
if (Intro.Default != LCD_None &&
!LSI->Lambda->getParent()->isFunctionOrMethod() &&
(getCurrentThisType().isNull() ||
CheckCXXThisCapture(SourceLocation(), /*Explicit=*/true,
/*BuildAndDiagnose=*/false)))
Diag(Intro.DefaultLoc, diag::err_capture_default_non_local);
}
void Sema::ActOnLambdaClosureParameters(
Scope *LambdaScope, MutableArrayRef<DeclaratorChunk::ParamInfo> Params) {
LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
PushDeclContext(LambdaScope, LSI->CallOperator);
for (const DeclaratorChunk::ParamInfo &P : Params) {
auto *Param = cast<ParmVarDecl>(P.Param);
Param->setOwningFunction(LSI->CallOperator);
if (Param->getIdentifier())
PushOnScopeChains(Param, LambdaScope, false);
}
// After the parameter list, we may parse a noexcept/requires/trailing return
// type which need to know whether the call operator constiture a dependent
// context, so we need to setup the FunctionTemplateDecl of generic lambdas
// now.
TemplateParameterList *TemplateParams =
getGenericLambdaTemplateParameterList(LSI, *this);
if (TemplateParams) {
AddTemplateParametersToLambdaCallOperator(LSI->CallOperator, LSI->Lambda,
TemplateParams);
LSI->Lambda->setLambdaIsGeneric(true);
LSI->ContainsUnexpandedParameterPack |=
TemplateParams->containsUnexpandedParameterPack();
}
LSI->AfterParameterList = true;
}
void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
Declarator &ParamInfo,
const DeclSpec &DS) {
LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
LSI->CallOperator->setConstexprKind(DS.getConstexprSpecifier());
SmallVector<ParmVarDecl *, 8> Params;
bool ExplicitResultType;
SourceLocation TypeLoc, CallOperatorLoc;
if (ParamInfo.getNumTypeObjects() == 0) {
CallOperatorLoc = TypeLoc = Intro.Range.getEnd();
} else {
unsigned Index;
ParamInfo.isFunctionDeclarator(Index);
const auto &Object = ParamInfo.getTypeObject(Index);
TypeLoc =
Object.Loc.isValid() ? Object.Loc : ParamInfo.getSourceRange().getEnd();
CallOperatorLoc = ParamInfo.getSourceRange().getEnd();
}
CXXRecordDecl *Class = LSI->Lambda;
CXXMethodDecl *Method = LSI->CallOperator;
TypeSourceInfo *MethodTyInfo = getLambdaType(
*this, Intro, ParamInfo, getCurScope(), TypeLoc, ExplicitResultType);
LSI->ExplicitParams = ParamInfo.getNumTypeObjects() != 0;
if (ParamInfo.isFunctionDeclarator() != 0 &&
!FTIHasSingleVoidParameter(ParamInfo.getFunctionTypeInfo())) {
const auto &FTI = ParamInfo.getFunctionTypeInfo();
Params.reserve(Params.size());
for (unsigned I = 0; I < FTI.NumParams; ++I) {
auto *Param = cast<ParmVarDecl>(FTI.Params[I].Param);
Param->setScopeInfo(0, Params.size());
Params.push_back(Param);
}
}
bool IsLambdaStatic =
ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static;
CompleteLambdaCallOperator(
Method, Intro.Range.getBegin(), CallOperatorLoc,
AssociatedConstraint(ParamInfo.getTrailingRequiresClause()), MethodTyInfo,
ParamInfo.getDeclSpec().getConstexprSpecifier(),
IsLambdaStatic ? SC_Static : SC_None, Params, ExplicitResultType);
CheckCXXDefaultArguments(Method);
// This represents the function body for the lambda function, check if we
// have to apply optnone due to a pragma.
AddRangeBasedOptnone(Method);
// code_seg attribute on lambda apply to the method.
if (Attr *A = getImplicitCodeSegOrSectionAttrForFunction(
Method, /*IsDefinition=*/true))
Method->addAttr(A);
// Attributes on the lambda apply to the method.
ProcessDeclAttributes(CurScope, Method, ParamInfo);
if (Context.getTargetInfo().getTriple().isAArch64())
ARM().CheckSMEFunctionDefAttributes(Method);
// CUDA lambdas get implicit host and device attributes.
if (getLangOpts().CUDA)
CUDA().SetLambdaAttrs(Method);
// OpenMP lambdas might get assumumption attributes.
if (LangOpts.OpenMP)
OpenMP().ActOnFinishedFunctionDefinitionInOpenMPAssumeScope(Method);
handleLambdaNumbering(Class, Method);
for (auto &&C : LSI->Captures) {
if (!C.isVariableCapture())
continue;
ValueDecl *Var = C.getVariable();
if (Var && Var->isInitCapture()) {
PushOnScopeChains(Var, CurScope, false);
}
}
auto CheckRedefinition = [&](ParmVarDecl *Param) {
for (const auto &Capture : Intro.Captures) {
if (Capture.Id == Param->getIdentifier()) {
Diag(Param->getLocation(), diag::err_parameter_shadow_capture);
Diag(Capture.Loc, diag::note_var_explicitly_captured_here)
<< Capture.Id << true;
return false;
}
}
return true;
};
for (ParmVarDecl *P : Params) {
if (!P->getIdentifier())
continue;
if (CheckRedefinition(P))
CheckShadow(CurScope, P);
PushOnScopeChains(P, CurScope);
}
// C++23 [expr.prim.lambda.capture]p5:
// If an identifier in a capture appears as the declarator-id of a parameter
// of the lambda-declarator's parameter-declaration-clause or as the name of a
// template parameter of the lambda-expression's template-parameter-list, the
// program is ill-formed.
TemplateParameterList *TemplateParams =
getGenericLambdaTemplateParameterList(LSI, *this);
if (TemplateParams) {
for (const auto *TP : TemplateParams->asArray()) {
if (!TP->getIdentifier())
continue;
for (const auto &Capture : Intro.Captures) {
if (Capture.Id == TP->getIdentifier()) {
Diag(Capture.Loc, diag::err_template_param_shadow) << Capture.Id;
NoteTemplateParameterLocation(*TP);
}
}
}
}
// C++20: dcl.decl.general p4:
// The optional requires-clause ([temp.pre]) in an init-declarator or
// member-declarator shall be present only if the declarator declares a
// templated function ([dcl.fct]).
if (const AssociatedConstraint &TRC = Method->getTrailingRequiresClause()) {
// [temp.pre]/8:
// An entity is templated if it is
// - a template,
// - an entity defined ([basic.def]) or created ([class.temporary]) in a
// templated entity,
// - a member of a templated entity,
// - an enumerator for an enumeration that is a templated entity, or
// - the closure type of a lambda-expression ([expr.prim.lambda.closure])
// appearing in the declaration of a templated entity. [Note 6: A local
// class, a local or block variable, or a friend function defined in a
// templated entity is a templated entity. — end note]
//
// A templated function is a function template or a function that is
// templated. A templated class is a class template or a class that is
// templated. A templated variable is a variable template or a variable
// that is templated.
// Note: we only have to check if this is defined in a template entity, OR
// if we are a template, since the rest don't apply. The requires clause
// applies to the call operator, which we already know is a member function,
// AND defined.
if (!Method->getDescribedFunctionTemplate() && !Method->isTemplated()) {
Diag(TRC.ConstraintExpr->getBeginLoc(),
diag::err_constrained_non_templated_function);
}
}
// Enter a new evaluation context to insulate the lambda from any
// cleanups from the enclosing full-expression.
PushExpressionEvaluationContextForFunction(
ExpressionEvaluationContext::PotentiallyEvaluated, LSI->CallOperator);
}
void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
bool IsInstantiation) {
LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
// Leave the expression-evaluation context.
DiscardCleanupsInEvaluationContext();
PopExpressionEvaluationContext();
// Leave the context of the lambda.
if (!IsInstantiation)
PopDeclContext();
// Finalize the lambda.
CXXRecordDecl *Class = LSI->Lambda;
Class->setInvalidDecl();
SmallVector<Decl*, 4> Fields(Class->fields());
ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
SourceLocation(), ParsedAttributesView());
CheckCompletedCXXClass(nullptr, Class);
PopFunctionScopeInfo();
}
template <typename Func>
static void repeatForLambdaConversionFunctionCallingConvs(
Sema &S, const FunctionProtoType &CallOpProto, Func F) {
CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
CallOpProto.isVariadic(), /*IsCXXMethod=*/false);
CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
CallOpProto.isVariadic(), /*IsCXXMethod=*/true);
CallingConv CallOpCC = CallOpProto.getCallConv();
/// Implement emitting a version of the operator for many of the calling
/// conventions for MSVC, as described here:
/// https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623.
/// Experimentally, we determined that cdecl, stdcall, fastcall, and
/// vectorcall are generated by MSVC when it is supported by the target.
/// Additionally, we are ensuring that the default-free/default-member and
/// call-operator calling convention are generated as well.
/// NOTE: We intentionally generate a 'thiscall' on Win32 implicitly from the
/// 'member default', despite MSVC not doing so. We do this in order to ensure
/// that someone who intentionally places 'thiscall' on the lambda call
/// operator will still get that overload, since we don't have the a way of
/// detecting the attribute by the time we get here.
if (S.getLangOpts().MSVCCompat) {
CallingConv Convs[] = {
CC_C, CC_X86StdCall, CC_X86FastCall, CC_X86VectorCall,
DefaultFree, DefaultMember, CallOpCC};
llvm::sort(Convs);
llvm::iterator_range<CallingConv *> Range(std::begin(Convs),
llvm::unique(Convs));
const TargetInfo &TI = S.getASTContext().getTargetInfo();
for (CallingConv C : Range) {
if (TI.checkCallingConvention(C) == TargetInfo::CCCR_OK)
F(C);
}
return;
}
if (CallOpCC == DefaultMember && DefaultMember != DefaultFree) {
F(DefaultFree);
F(DefaultMember);
} else {
F(CallOpCC);
}
}
// Returns the 'standard' calling convention to be used for the lambda
// conversion function, that is, the 'free' function calling convention unless
// it is overridden by a non-default calling convention attribute.
static CallingConv
getLambdaConversionFunctionCallConv(Sema &S,
const FunctionProtoType *CallOpProto) {
CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
CallOpProto->isVariadic(), /*IsCXXMethod=*/true);
CallingConv CallOpCC = CallOpProto->getCallConv();
// If the call-operator hasn't been changed, return both the 'free' and
// 'member' function calling convention.
if (CallOpCC == DefaultMember && DefaultMember != DefaultFree)
return DefaultFree;
return CallOpCC;
}
QualType Sema::getLambdaConversionFunctionResultType(
const FunctionProtoType *CallOpProto, CallingConv CC) {
const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
CallOpProto->getExtProtoInfo();
FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(CC);
InvokerExtInfo.TypeQuals = Qualifiers();
assert(InvokerExtInfo.RefQualifier == RQ_None &&
"Lambda's call operator should not have a reference qualifier");
return Context.getFunctionType(CallOpProto->getReturnType(),
CallOpProto->getParamTypes(), InvokerExtInfo);
}
/// Add a lambda's conversion to function pointer, as described in
/// C++11 [expr.prim.lambda]p6.
static void addFunctionPointerConversion(Sema &S, SourceRange IntroducerRange,
CXXRecordDecl *Class,
CXXMethodDecl *CallOperator,
QualType InvokerFunctionTy) {
// This conversion is explicitly disabled if the lambda's function has
// pass_object_size attributes on any of its parameters.
auto HasPassObjectSizeAttr = [](const ParmVarDecl *P) {
return P->hasAttr<PassObjectSizeAttr>();
};
if (llvm::any_of(CallOperator->parameters(), HasPassObjectSizeAttr))
return;
// Add the conversion to function pointer.
QualType PtrToFunctionTy = S.Context.getPointerType(InvokerFunctionTy);
// Create the type of the conversion function.
FunctionProtoType::ExtProtoInfo ConvExtInfo(
S.Context.getDefaultCallingConvention(
/*IsVariadic=*/false, /*IsCXXMethod=*/true));
// The conversion function is always const and noexcept.
ConvExtInfo.TypeQuals = Qualifiers();
ConvExtInfo.TypeQuals.addConst();
ConvExtInfo.ExceptionSpec.Type = EST_BasicNoexcept;
QualType ConvTy = S.Context.getFunctionType(PtrToFunctionTy, {}, ConvExtInfo);
SourceLocation Loc = IntroducerRange.getBegin();
DeclarationName ConversionName
= S.Context.DeclarationNames.getCXXConversionFunctionName(
S.Context.getCanonicalType(PtrToFunctionTy));
// Construct a TypeSourceInfo for the conversion function, and wire
// all the parameters appropriately for the FunctionProtoTypeLoc
// so that everything works during transformation/instantiation of
// generic lambdas.
// The main reason for wiring up the parameters of the conversion
// function with that of the call operator is so that constructs
// like the following work:
// auto L = [](auto b) { <-- 1
// return [](auto a) -> decltype(a) { <-- 2
// return a;
// };
// };
// int (*fp)(int) = L(5);
// Because the trailing return type can contain DeclRefExprs that refer
// to the original call operator's variables, we hijack the call
// operators ParmVarDecls below.
TypeSourceInfo *ConvNamePtrToFunctionTSI =
S.Context.getTrivialTypeSourceInfo(PtrToFunctionTy, Loc);
DeclarationNameLoc ConvNameLoc =
DeclarationNameLoc::makeNamedTypeLoc(ConvNamePtrToFunctionTSI);
// The conversion function is a conversion to a pointer-to-function.
TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(ConvTy, Loc);
FunctionProtoTypeLoc ConvTL =
ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
// Get the result of the conversion function which is a pointer-to-function.
PointerTypeLoc PtrToFunctionTL =
ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
// Do the same for the TypeSourceInfo that is used to name the conversion
// operator.
PointerTypeLoc ConvNamePtrToFunctionTL =
ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
// Get the underlying function types that the conversion function will
// be converting to (should match the type of the call operator).
FunctionProtoTypeLoc CallOpConvTL =
PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
FunctionProtoTypeLoc CallOpConvNameTL =
ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
// Wire up the FunctionProtoTypeLocs with the call operator's parameters.
// These parameter's are essentially used to transform the name and
// the type of the conversion operator. By using the same parameters
// as the call operator's we don't have to fix any back references that
// the trailing return type of the call operator's uses (such as
// decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
// - we can simply use the return type of the call operator, and
// everything should work.
SmallVector<ParmVarDecl *, 4> InvokerParams;
for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
ParmVarDecl *From = CallOperator->getParamDecl(I);
InvokerParams.push_back(ParmVarDecl::Create(
S.Context,
// Temporarily add to the TU. This is set to the invoker below.
S.Context.getTranslationUnitDecl(), From->getBeginLoc(),
From->getLocation(), From->getIdentifier(), From->getType(),
From->getTypeSourceInfo(), From->getStorageClass(),
/*DefArg=*/nullptr));
CallOpConvTL.setParam(I, From);
CallOpConvNameTL.setParam(I, From);
}
CXXConversionDecl *Conversion = CXXConversionDecl::Create(
S.Context, Class, Loc,
DeclarationNameInfo(ConversionName, Loc, ConvNameLoc), ConvTy, ConvTSI,
S.getCurFPFeatures().isFPConstrained(),
/*isInline=*/true, ExplicitSpecifier(),
S.getLangOpts().CPlusPlus17 ? ConstexprSpecKind::Constexpr
: ConstexprSpecKind::Unspecified,
CallOperator->getBody()->getEndLoc());
Conversion->setAccess(AS_public);
Conversion->setImplicit(true);
// A non-generic lambda may still be a templated entity. We need to preserve
// constraints when converting the lambda to a function pointer. See GH63181.
if (const AssociatedConstraint &Requires =
CallOperator->getTrailingRequiresClause())
Conversion->setTrailingRequiresClause(Requires);
if (Class->isGenericLambda()) {
// Create a template version of the conversion operator, using the template
// parameter list of the function call operator.
FunctionTemplateDecl *TemplateCallOperator =
CallOperator->getDescribedFunctionTemplate();
FunctionTemplateDecl *ConversionTemplate =
FunctionTemplateDecl::Create(S.Context, Class,
Loc, ConversionName,
TemplateCallOperator->getTemplateParameters(),
Conversion);
ConversionTemplate->setAccess(AS_public);
ConversionTemplate->setImplicit(true);
Conversion->setDescribedFunctionTemplate(ConversionTemplate);
Class->addDecl(ConversionTemplate);
} else
Class->addDecl(Conversion);
// If the lambda is not static, we need to add a static member
// function that will be the result of the conversion with a
// certain unique ID.
// When it is static we just return the static call operator instead.
if (CallOperator->isImplicitObjectMemberFunction()) {
DeclarationName InvokerName =
&S.Context.Idents.get(getLambdaStaticInvokerName());
// FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
// we should get a prebuilt TrivialTypeSourceInfo from Context
// using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
// then rewire the parameters accordingly, by hoisting up the InvokeParams
// loop below and then use its Params to set Invoke->setParams(...) below.
// This would avoid the 'const' qualifier of the calloperator from
// contaminating the type of the invoker, which is currently adjusted
// in SemaTemplateDeduction.cpp:DeduceTemplateArguments. Fixing the
// trailing return type of the invoker would require a visitor to rebuild
// the trailing return type and adjusting all back DeclRefExpr's to refer
// to the new static invoker parameters - not the call operator's.
CXXMethodDecl *Invoke = CXXMethodDecl::Create(
S.Context, Class, Loc, DeclarationNameInfo(InvokerName, Loc),
InvokerFunctionTy, CallOperator->getTypeSourceInfo(), SC_Static,
S.getCurFPFeatures().isFPConstrained(),
/*isInline=*/true, CallOperator->getConstexprKind(),
CallOperator->getBody()->getEndLoc());
for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
InvokerParams[I]->setOwningFunction(Invoke);
Invoke->setParams(InvokerParams);
Invoke->setAccess(AS_private);
Invoke->setImplicit(true);
if (Class->isGenericLambda()) {
FunctionTemplateDecl *TemplateCallOperator =
CallOperator->getDescribedFunctionTemplate();
FunctionTemplateDecl *StaticInvokerTemplate =
FunctionTemplateDecl::Create(
S.Context, Class, Loc, InvokerName,
TemplateCallOperator->getTemplateParameters(), Invoke);
StaticInvokerTemplate->setAccess(AS_private);
StaticInvokerTemplate->setImplicit(true);
Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
Class->addDecl(StaticInvokerTemplate);
} else
Class->addDecl(Invoke);
}
}
/// Add a lambda's conversion to function pointers, as described in
/// C++11 [expr.prim.lambda]p6. Note that in most cases, this should emit only a
/// single pointer conversion. In the event that the default calling convention
/// for free and member functions is different, it will emit both conventions.
static void addFunctionPointerConversions(Sema &S, SourceRange IntroducerRange,
CXXRecordDecl *Class,
CXXMethodDecl *CallOperator) {
const FunctionProtoType *CallOpProto =
CallOperator->getType()->castAs<FunctionProtoType>();
repeatForLambdaConversionFunctionCallingConvs(
S, *CallOpProto, [&](CallingConv CC) {
QualType InvokerFunctionTy =
S.getLambdaConversionFunctionResultType(CallOpProto, CC);
addFunctionPointerConversion(S, IntroducerRange, Class, CallOperator,
InvokerFunctionTy);
});
}
/// Add a lambda's conversion to block pointer.
static void addBlockPointerConversion(Sema &S,
SourceRange IntroducerRange,
CXXRecordDecl *Class,
CXXMethodDecl *CallOperator) {
const FunctionProtoType *CallOpProto =
CallOperator->getType()->castAs<FunctionProtoType>();
QualType FunctionTy = S.getLambdaConversionFunctionResultType(
CallOpProto, getLambdaConversionFunctionCallConv(S, CallOpProto));
QualType BlockPtrTy = S.Context.getBlockPointerType(FunctionTy);
FunctionProtoType::ExtProtoInfo ConversionEPI(
S.Context.getDefaultCallingConvention(
/*IsVariadic=*/false, /*IsCXXMethod=*/true));
ConversionEPI.TypeQuals = Qualifiers();
ConversionEPI.TypeQuals.addConst();
QualType ConvTy = S.Context.getFunctionType(BlockPtrTy, {}, ConversionEPI);
SourceLocation Loc = IntroducerRange.getBegin();
DeclarationName Name
= S.Context.DeclarationNames.getCXXConversionFunctionName(
S.Context.getCanonicalType(BlockPtrTy));
DeclarationNameLoc NameLoc = DeclarationNameLoc::makeNamedTypeLoc(
S.Context.getTrivialTypeSourceInfo(BlockPtrTy, Loc));
CXXConversionDecl *Conversion = CXXConversionDecl::Create(
S.Context, Class, Loc, DeclarationNameInfo(Name, Loc, NameLoc), ConvTy,
S.Context.getTrivialTypeSourceInfo(ConvTy, Loc),
S.getCurFPFeatures().isFPConstrained(),
/*isInline=*/true, ExplicitSpecifier(), ConstexprSpecKind::Unspecified,
CallOperator->getBody()->getEndLoc());
Conversion->setAccess(AS_public);
Conversion->setImplicit(true);
Class->addDecl(Conversion);
}
ExprResult Sema::BuildCaptureInit(const Capture &Cap,
SourceLocation ImplicitCaptureLoc,
bool IsOpenMPMapping) {
// VLA captures don't have a stored initialization expression.
if (Cap.isVLATypeCapture())
return ExprResult();
// An init-capture is initialized directly from its stored initializer.
if (Cap.isInitCapture())
return cast<VarDecl>(Cap.getVariable())->getInit();
// For anything else, build an initialization expression. For an implicit
// capture, the capture notionally happens at the capture-default, so use
// that location here.
SourceLocation Loc =
ImplicitCaptureLoc.isValid() ? ImplicitCaptureLoc : Cap.getLocation();
// C++11 [expr.prim.lambda]p21:
// When the lambda-expression is evaluated, the entities that
// are captured by copy are used to direct-initialize each
// corresponding non-static data member of the resulting closure
// object. (For array members, the array elements are
// direct-initialized in increasing subscript order.) These
// initializations are performed in the (unspecified) order in
// which the non-static data members are declared.
// C++ [expr.prim.lambda]p12:
// An entity captured by a lambda-expression is odr-used (3.2) in
// the scope containing the lambda-expression.
ExprResult Init;
IdentifierInfo *Name = nullptr;
if (Cap.isThisCapture()) {
QualType ThisTy = getCurrentThisType();
Expr *This = BuildCXXThisExpr(Loc, ThisTy, ImplicitCaptureLoc.isValid());
if (Cap.isCopyCapture())
Init = CreateBuiltinUnaryOp(Loc, UO_Deref, This);
else
Init = This;
} else {
assert(Cap.isVariableCapture() && "unknown kind of capture");
ValueDecl *Var = Cap.getVariable();
Name = Var->getIdentifier();
Init = BuildDeclarationNameExpr(
CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
}
// In OpenMP, the capture kind doesn't actually describe how to capture:
// variables are "mapped" onto the device in a process that does not formally
// make a copy, even for a "copy capture".
if (IsOpenMPMapping)
return Init;
if (Init.isInvalid())
return ExprError();
Expr *InitExpr = Init.get();
InitializedEntity Entity = InitializedEntity::InitializeLambdaCapture(
Name, Cap.getCaptureType(), Loc);
InitializationKind InitKind =
InitializationKind::CreateDirect(Loc, Loc, Loc);
InitializationSequence InitSeq(*this, Entity, InitKind, InitExpr);
return InitSeq.Perform(*this, Entity, InitKind, InitExpr);
}
ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body) {
LambdaScopeInfo &LSI = *cast<LambdaScopeInfo>(FunctionScopes.back());
if (LSI.CallOperator->hasAttr<SYCLKernelEntryPointAttr>())
SYCL().CheckSYCLEntryPointFunctionDecl(LSI.CallOperator);
ActOnFinishFunctionBody(LSI.CallOperator, Body, /*IsInstantiation=*/false,
/*RetainFunctionScopeInfo=*/true);
return BuildLambdaExpr(StartLoc, Body->getEndLoc());
}
static LambdaCaptureDefault
mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
switch (ICS) {
case CapturingScopeInfo::ImpCap_None:
return LCD_None;
case CapturingScopeInfo::ImpCap_LambdaByval:
return LCD_ByCopy;
case CapturingScopeInfo::ImpCap_CapturedRegion:
case CapturingScopeInfo::ImpCap_LambdaByref:
return LCD_ByRef;
case CapturingScopeInfo::ImpCap_Block:
llvm_unreachable("block capture in lambda");
}
llvm_unreachable("Unknown implicit capture style");
}
bool Sema::CaptureHasSideEffects(const Capture &From) {
if (From.isInitCapture()) {
Expr *Init = cast<VarDecl>(From.getVariable())->getInit();
if (Init && Init->HasSideEffects(Context))
return true;
}
if (!From.isCopyCapture())
return false;
const QualType T = From.isThisCapture()
? getCurrentThisType()->getPointeeType()
: From.getCaptureType();
if (T.isVolatileQualified())
return true;
const Type *BaseT = T->getBaseElementTypeUnsafe();
if (const CXXRecordDecl *RD = BaseT->getAsCXXRecordDecl())
return !RD->isCompleteDefinition() || !RD->hasTrivialCopyConstructor() ||
!RD->hasTrivialDestructor();
return false;
}
bool Sema::DiagnoseUnusedLambdaCapture(SourceRange CaptureRange,
SourceRange FixItRange,
const Capture &From) {
if (CaptureHasSideEffects(From))
return false;
if (From.isVLATypeCapture())
return false;
// FIXME: maybe we should warn on these if we can find a sensible diagnostic
// message
if (From.isInitCapture() &&
From.getVariable()->isPlaceholderVar(getLangOpts()))
return false;
auto diag = Diag(From.getLocation(), diag::warn_unused_lambda_capture);
if (From.isThisCapture())
diag << "'this'";
else
diag << From.getVariable();
diag << From.isNonODRUsed();
// If we were able to resolve the fixit range we'll create a fixit,
// otherwise we just use the raw capture range for the diagnostic.
if (FixItRange.isValid())
diag << FixItHint::CreateRemoval(FixItRange);
else
diag << CaptureRange;
return true;
}
/// Create a field within the lambda class or captured statement record for the
/// given capture.
FieldDecl *Sema::BuildCaptureField(RecordDecl *RD,
const sema::Capture &Capture) {
SourceLocation Loc = Capture.getLocation();
QualType FieldType = Capture.getCaptureType();
TypeSourceInfo *TSI = nullptr;
if (Capture.isVariableCapture()) {
const auto *Var = dyn_cast_or_null<VarDecl>(Capture.getVariable());
if (Var && Var->isInitCapture())
TSI = Var->getTypeSourceInfo();
}
// FIXME: Should we really be doing this? A null TypeSourceInfo seems more
// appropriate, at least for an implicit capture.
if (!TSI)
TSI = Context.getTrivialTypeSourceInfo(FieldType, Loc);
// Build the non-static data member.
FieldDecl *Field =
FieldDecl::Create(Context, RD, /*StartLoc=*/Loc, /*IdLoc=*/Loc,
/*Id=*/nullptr, FieldType, TSI, /*BW=*/nullptr,
/*Mutable=*/false, ICIS_NoInit);
// If the variable being captured has an invalid type, mark the class as
// invalid as well.
if (!FieldType->isDependentType()) {
if (RequireCompleteSizedType(Loc, FieldType,
diag::err_field_incomplete_or_sizeless)) {
RD->setInvalidDecl();
Field->setInvalidDecl();
} else {
NamedDecl *Def;
FieldType->isIncompleteType(&Def);
if (Def && Def->isInvalidDecl()) {
RD->setInvalidDecl();
Field->setInvalidDecl();
}
}
}
Field->setImplicit(true);
Field->setAccess(AS_private);
RD->addDecl(Field);
if (Capture.isVLATypeCapture())
Field->setCapturedVLAType(Capture.getCapturedVLAType());
return Field;
}
static SourceRange
ConstructFixItRangeForUnusedCapture(Sema &S, SourceRange CaptureRange,
SourceLocation PrevCaptureLoc,
bool CurHasPreviousCapture, bool IsLast) {
if (!CaptureRange.isValid())
return SourceRange();
auto GetTrailingEndLocation = [&](SourceLocation StartPoint) {
SourceRange NextToken = S.getRangeForNextToken(
StartPoint, /*IncludeMacros=*/false, /*IncludeComments=*/true);
if (!NextToken.isValid())
return SourceLocation();
// Return the last location preceding the next token
return NextToken.getBegin().getLocWithOffset(-1);
};
if (!CurHasPreviousCapture && !IsLast) {
// If there are no captures preceding this capture, remove the
// trailing comma and anything up to the next token
SourceRange CommaRange =
S.getRangeForNextToken(CaptureRange.getEnd(), /*IncludeMacros=*/false,
/*IncludeComments=*/false, tok::comma);
SourceLocation FixItEnd = GetTrailingEndLocation(CommaRange.getBegin());
return SourceRange(CaptureRange.getBegin(), FixItEnd);
}
// Otherwise, remove the comma since the last used capture, and
// anything up to the next token
SourceLocation FixItStart = S.getLocForEndOfToken(PrevCaptureLoc);
SourceLocation FixItEnd = GetTrailingEndLocation(CaptureRange.getEnd());
return SourceRange(FixItStart, FixItEnd);
}
ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc,
SourceLocation EndLoc) {
LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
// Collect information from the lambda scope.
SmallVector<LambdaCapture, 4> Captures;
SmallVector<Expr *, 4> CaptureInits;
SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
LambdaCaptureDefault CaptureDefault =
mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
CXXRecordDecl *Class = LSI->Lambda;
CXXMethodDecl *CallOperator = LSI->CallOperator;
SourceRange IntroducerRange = LSI->IntroducerRange;
bool ExplicitParams = LSI->ExplicitParams;
bool ExplicitResultType = !LSI->HasImplicitReturnType;
CleanupInfo LambdaCleanup = LSI->Cleanup;
bool ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
bool IsGenericLambda = Class->isGenericLambda();
CallOperator->setLexicalDeclContext(Class);
Decl *TemplateOrNonTemplateCallOperatorDecl =
CallOperator->getDescribedFunctionTemplate()
? CallOperator->getDescribedFunctionTemplate()
: cast<Decl>(CallOperator);
// FIXME: Is this really the best choice? Keeping the lexical decl context
// set as CurContext seems more faithful to the source.
TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
PopExpressionEvaluationContext();
sema::AnalysisBasedWarnings::Policy WP =
AnalysisWarnings.getPolicyInEffectAt(EndLoc);
// We cannot release LSI until we finish computing captures, which
// requires the scope to be popped.
Sema::PoppedFunctionScopePtr _ = PopFunctionScopeInfo(&WP, LSI->CallOperator);
// True if the current capture has a used capture or default before it.
bool CurHasPreviousCapture = CaptureDefault != LCD_None;
SourceLocation PrevCaptureLoc =
CurHasPreviousCapture ? CaptureDefaultLoc : IntroducerRange.getBegin();
for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I) {
const Capture &From = LSI->Captures[I];
if (From.isInvalid())
return ExprError();
assert(!From.isBlockCapture() && "Cannot capture __block variables");
bool IsImplicit = I >= LSI->NumExplicitCaptures;
SourceLocation ImplicitCaptureLoc =
IsImplicit ? CaptureDefaultLoc : SourceLocation();
// Use source ranges of explicit captures for fixits where available.
SourceRange CaptureRange = LSI->ExplicitCaptureRanges[I];
// Warn about unused explicit captures.
bool IsCaptureUsed = true;
if (!CurContext->isDependentContext() && !IsImplicit && !From.isODRUsed()) {
// Initialized captures that are non-ODR used may not be eliminated.
// FIXME: Where did the IsGenericLambda here come from?
bool NonODRUsedInitCapture =
IsGenericLambda && From.isNonODRUsed() && From.isInitCapture();
if (!NonODRUsedInitCapture) {
bool IsLast = (I + 1) == LSI->NumExplicitCaptures;
SourceRange FixItRange = ConstructFixItRangeForUnusedCapture(
*this, CaptureRange, PrevCaptureLoc, CurHasPreviousCapture, IsLast);
IsCaptureUsed =
!DiagnoseUnusedLambdaCapture(CaptureRange, FixItRange, From);
}
}
if (CaptureRange.isValid()) {
CurHasPreviousCapture |= IsCaptureUsed;
PrevCaptureLoc = CaptureRange.getEnd();
}
// Map the capture to our AST representation.
LambdaCapture Capture = [&] {
if (From.isThisCapture()) {
// Capturing 'this' implicitly with a default of '[=]' is deprecated,
// because it results in a reference capture. Don't warn prior to
// C++2a; there's nothing that can be done about it before then.
if (getLangOpts().CPlusPlus20 && IsImplicit &&
CaptureDefault == LCD_ByCopy) {
Diag(From.getLocation(), diag::warn_deprecated_this_capture);
Diag(CaptureDefaultLoc, diag::note_deprecated_this_capture)
<< FixItHint::CreateInsertion(
getLocForEndOfToken(CaptureDefaultLoc), ", this");
}
return LambdaCapture(From.getLocation(), IsImplicit,
From.isCopyCapture() ? LCK_StarThis : LCK_This);
} else if (From.isVLATypeCapture()) {
return LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType);
} else {
assert(From.isVariableCapture() && "unknown kind of capture");
ValueDecl *Var = From.getVariable();
LambdaCaptureKind Kind = From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
return LambdaCapture(From.getLocation(), IsImplicit, Kind, Var,
From.getEllipsisLoc());
}
}();
// Form the initializer for the capture field.
ExprResult Init = BuildCaptureInit(From, ImplicitCaptureLoc);
// FIXME: Skip this capture if the capture is not used, the initializer
// has no side-effects, the type of the capture is trivial, and the
// lambda is not externally visible.
// Add a FieldDecl for the capture and form its initializer.
BuildCaptureField(Class, From);
Captures.push_back(Capture);
CaptureInits.push_back(Init.get());
if (LangOpts.CUDA)
CUDA().CheckLambdaCapture(CallOperator, From);
}
Class->setCaptures(Context, Captures);
// 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)
addFunctionPointerConversions(*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.
// FIXME: Fix generic lambda to block conversions.
if (getLangOpts().Blocks && getLangOpts().ObjC && !IsGenericLambda)
addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
// Finalize the lambda class.
SmallVector<Decl *, 4> Fields(Class->fields());
ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
SourceLocation(), ParsedAttributesView());
CheckCompletedCXXClass(nullptr, Class);
Cleanup.mergeFrom(LambdaCleanup);
LambdaExpr *Lambda =
LambdaExpr::Create(Context, Class, IntroducerRange, CaptureDefault,
CaptureDefaultLoc, ExplicitParams, ExplicitResultType,
CaptureInits, EndLoc, ContainsUnexpandedParameterPack);
// If the lambda expression's call operator is not explicitly marked constexpr
// and is not dependent, analyze the call operator to infer
// its constexpr-ness, suppressing diagnostics while doing so.
if (getLangOpts().CPlusPlus17 && !CallOperator->isInvalidDecl() &&
!CallOperator->isConstexpr() &&
!isa<CoroutineBodyStmt>(CallOperator->getBody()) &&
!Class->isDependentContext()) {
CallOperator->setConstexprKind(
CheckConstexprFunctionDefinition(CallOperator,
CheckConstexprKind::CheckValid)
? ConstexprSpecKind::Constexpr
: ConstexprSpecKind::Unspecified);
}
// Emit delayed shadowing warnings now that the full capture list is known.
DiagnoseShadowingLambdaDecls(LSI);
if (!CurContext->isDependentContext()) {
switch (ExprEvalContexts.back().Context) {
// C++11 [expr.prim.lambda]p2:
// A lambda-expression shall not appear in an unevaluated operand
// (Clause 5).
case ExpressionEvaluationContext::Unevaluated:
case ExpressionEvaluationContext::UnevaluatedList:
case ExpressionEvaluationContext::UnevaluatedAbstract:
// C++1y [expr.const]p2:
// A conditional-expression e is a core constant expression unless the
// evaluation of e, following the rules of the abstract machine, would
// evaluate [...] a lambda-expression.
//
// This is technically incorrect, there are some constant evaluated contexts
// where this should be allowed. We should probably fix this when DR1607 is
// ratified, it lays out the exact set of conditions where we shouldn't
// allow a lambda-expression.
case ExpressionEvaluationContext::ConstantEvaluated:
case ExpressionEvaluationContext::ImmediateFunctionContext:
// 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 ExpressionEvaluationContext::DiscardedStatement:
case ExpressionEvaluationContext::PotentiallyEvaluated:
case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
break;
}
maybeAddDeclWithEffects(LSI->CallOperator);
}
return MaybeBindToTemporary(Lambda);
}
ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
SourceLocation ConvLocation,
CXXConversionDecl *Conv,
Expr *Src) {
// Make sure that the lambda call operator is marked used.
CXXRecordDecl *Lambda = Conv->getParent();
CXXMethodDecl *CallOperator
= cast<CXXMethodDecl>(
Lambda->lookup(
Context.DeclarationNames.getCXXOperatorName(OO_Call)).front());
CallOperator->setReferenced();
CallOperator->markUsed(Context);
ExprResult Init = PerformCopyInitialization(
InitializedEntity::InitializeLambdaToBlock(ConvLocation, Src->getType()),
CurrentLocation, Src);
if (!Init.isInvalid())
Init = ActOnFinishFullExpr(Init.get(), /*DiscardedValue*/ false);
if (Init.isInvalid())
return ExprError();
// Create the new block to be returned.
BlockDecl *Block = BlockDecl::Create(Context, CurContext, ConvLocation);
// Set the type information.
Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
Block->setIsVariadic(CallOperator->isVariadic());
Block->setBlockMissingReturnType(false);
// Add parameters.
SmallVector<ParmVarDecl *, 4> BlockParams;
for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
ParmVarDecl *From = CallOperator->getParamDecl(I);
BlockParams.push_back(ParmVarDecl::Create(
Context, Block, From->getBeginLoc(), From->getLocation(),
From->getIdentifier(), From->getType(), From->getTypeSourceInfo(),
From->getStorageClass(),
/*DefArg=*/nullptr));
}
Block->setParams(BlockParams);
Block->setIsConversionFromLambda(true);
// Add capture. The capture uses a fake variable, which doesn't correspond
// to any actual memory location. However, the initializer copy-initializes
// the lambda object.
TypeSourceInfo *CapVarTSI =
Context.getTrivialTypeSourceInfo(Src->getType());
VarDecl *CapVar = VarDecl::Create(Context, Block, ConvLocation,
ConvLocation, nullptr,
Src->getType(), CapVarTSI,
SC_None);
BlockDecl::Capture Capture(/*variable=*/CapVar, /*byRef=*/false,
/*nested=*/false, /*copy=*/Init.get());
Block->setCaptures(Context, Capture, /*CapturesCXXThis=*/false);
// Add a fake function body to the block. IR generation is responsible
// for filling in the actual body, which cannot be expressed as an AST.
Block->setBody(new (Context) CompoundStmt(ConvLocation));
// Create the block literal expression.
// TODO: Do we ever get here if we have unexpanded packs in the lambda???
Expr *BuildBlock =
new (Context) BlockExpr(Block, Conv->getConversionType(),
/*ContainsUnexpandedParameterPack=*/false);
ExprCleanupObjects.push_back(Block);
Cleanup.setExprNeedsCleanups(true);
return BuildBlock;
}
static FunctionDecl *getPatternFunctionDecl(FunctionDecl *FD) {
if (FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization) {
while (FD->getInstantiatedFromMemberFunction())
FD = FD->getInstantiatedFromMemberFunction();
return FD;
}
if (FD->getTemplatedKind() == FunctionDecl::TK_DependentNonTemplate)
return FD->getInstantiatedFromDecl();
FunctionTemplateDecl *FTD = FD->getPrimaryTemplate();
if (!FTD)
return nullptr;
while (FTD->getInstantiatedFromMemberTemplate())
FTD = FTD->getInstantiatedFromMemberTemplate();
return FTD->getTemplatedDecl();
}
bool Sema::addInstantiatedCapturesToScope(
FunctionDecl *Function, const FunctionDecl *PatternDecl,
LocalInstantiationScope &Scope,
const MultiLevelTemplateArgumentList &TemplateArgs) {
const auto *LambdaClass = cast<CXXMethodDecl>(Function)->getParent();
const auto *LambdaPattern = cast<CXXMethodDecl>(PatternDecl)->getParent();
unsigned Instantiated = 0;
// FIXME: This is a workaround for not having deferred lambda body
// instantiation.
// When transforming a lambda's body, if we encounter another call to a
// nested lambda that contains a constraint expression, we add all of the
// outer lambda's instantiated captures to the current instantiation scope to
// facilitate constraint evaluation. However, these captures don't appear in
// the CXXRecordDecl until after the lambda expression is rebuilt, so we
// pull them out from the corresponding LSI.
LambdaScopeInfo *InstantiatingScope = nullptr;
if (LambdaPattern->capture_size() && !LambdaClass->capture_size()) {
for (FunctionScopeInfo *Scope : llvm::reverse(FunctionScopes)) {
auto *LSI = dyn_cast<LambdaScopeInfo>(Scope);
if (!LSI || getPatternFunctionDecl(LSI->CallOperator) != PatternDecl)
continue;
InstantiatingScope = LSI;
break;
}
assert(InstantiatingScope);
}
auto AddSingleCapture = [&](const ValueDecl *CapturedPattern,
unsigned Index) {
ValueDecl *CapturedVar =
InstantiatingScope ? InstantiatingScope->Captures[Index].getVariable()
: LambdaClass->getCapture(Index)->getCapturedVar();
assert(CapturedVar->isInitCapture());
Scope.InstantiatedLocal(CapturedPattern, CapturedVar);
};
for (const LambdaCapture &CapturePattern : LambdaPattern->captures()) {
if (!CapturePattern.capturesVariable()) {
Instantiated++;
continue;
}
ValueDecl *CapturedPattern = CapturePattern.getCapturedVar();
if (!CapturedPattern->isInitCapture()) {
Instantiated++;
continue;
}
if (!CapturedPattern->isParameterPack()) {
AddSingleCapture(CapturedPattern, Instantiated++);
} else {
Scope.MakeInstantiatedLocalArgPack(CapturedPattern);
SmallVector<UnexpandedParameterPack, 2> Unexpanded;
SemaRef.collectUnexpandedParameterPacks(
dyn_cast<VarDecl>(CapturedPattern)->getInit(), Unexpanded);
auto NumArgumentsInExpansion =
getNumArgumentsInExpansionFromUnexpanded(Unexpanded, TemplateArgs);
if (!NumArgumentsInExpansion)
continue;
for (unsigned Arg = 0; Arg < *NumArgumentsInExpansion; ++Arg)
AddSingleCapture(CapturedPattern, Instantiated++);
}
}
return false;
}
Sema::LambdaScopeForCallOperatorInstantiationRAII::
LambdaScopeForCallOperatorInstantiationRAII(
Sema &SemaRef, FunctionDecl *FD, MultiLevelTemplateArgumentList MLTAL,
LocalInstantiationScope &Scope, bool ShouldAddDeclsFromParentScope)
: FunctionScopeRAII(SemaRef) {
if (!isLambdaCallOperator(FD)) {
FunctionScopeRAII::disable();
return;
}
SemaRef.RebuildLambdaScopeInfo(cast<CXXMethodDecl>(FD));
FunctionDecl *FDPattern = getPatternFunctionDecl(FD);
if (!FDPattern)
return;
if (!ShouldAddDeclsFromParentScope)
return;
llvm::SmallVector<std::pair<FunctionDecl *, FunctionDecl *>, 4>
InstantiationAndPatterns;
while (FDPattern && FD) {
InstantiationAndPatterns.emplace_back(FDPattern, FD);
FDPattern =
dyn_cast<FunctionDecl>(getLambdaAwareParentOfDeclContext(FDPattern));
FD = dyn_cast<FunctionDecl>(getLambdaAwareParentOfDeclContext(FD));
}
// Add instantiated parameters and local vars to scopes, starting from the
// outermost lambda to the innermost lambda. This ordering ensures that
// the outer instantiations can be found when referenced from within inner
// lambdas.
//
// auto L = [](auto... x) {
// return [](decltype(x)... y) { }; // Instantiating y needs x
// };
//
for (auto [FDPattern, FD] : llvm::reverse(InstantiationAndPatterns)) {
SemaRef.addInstantiatedParametersToScope(FD, FDPattern, Scope, MLTAL);
SemaRef.addInstantiatedLocalVarsToScope(FD, FDPattern, Scope);
if (isLambdaCallOperator(FD))
SemaRef.addInstantiatedCapturesToScope(FD, FDPattern, Scope, MLTAL);
}
}