llvm/clang/lib/Sema/SemaLambda.cpp

//===--- 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/SemaCUDA.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/SemaOpenMP.h"
#include "clang/Sema/Template.h"
#include "llvm/ADT/STLExtras.h"
#include <optional>
usingnamespaceclang;
usingnamespacesema;

/// 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 std::optional<unsigned> 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 std::optional<unsigned>
getStackIndexOfNearestEnclosingCaptureReadyLambda(
    ArrayRef<const clang::sema::FunctionScopeInfo *> FunctionScopes,
    ValueDecl *VarToCapture) { … }

/// 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 std::optional<unsigned> 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.

std::optional<unsigned>
clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
    ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
    ValueDecl *VarToCapture, Sema &S) { … }

static inline TemplateParameterList *
getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) { … }

CXXRecordDecl *
Sema::createLambdaClosureType(SourceRange IntroducerRange, TypeSourceInfo *Info,
                              unsigned LambdaDependencyKind,
                              LambdaCaptureDefault CaptureDefault) { … }

/// Determine whether the given context is or is enclosed in an inline
/// function.
static bool isInInlineFunction(const DeclContext *DC) { … }

std::tuple<MangleNumberingContext *, Decl *>
Sema::getCurrentMangleNumberContext(const DeclContext *DC) { … }

static QualType
buildTypeForLambdaCallOperator(Sema &S, clang::CXXRecordDecl *Class,
                               TemplateParameterList *TemplateParams,
                               TypeSourceInfo *MethodTypeInfo) { … }

// [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) { … }

void Sema::handleLambdaNumbering(
    CXXRecordDecl *Class, CXXMethodDecl *Method,
    std::optional<CXXRecordDecl::LambdaNumbering> NumberingOverride) { … }

static void buildLambdaScopeReturnType(Sema &S, LambdaScopeInfo *LSI,
                                       CXXMethodDecl *CallOperator,
                                       bool ExplicitResultType) { … }

void Sema::buildLambdaScope(LambdaScopeInfo *LSI, CXXMethodDecl *CallOperator,
                            SourceRange IntroducerRange,
                            LambdaCaptureDefault CaptureDefault,
                            SourceLocation CaptureDefaultLoc,
                            bool ExplicitParams, bool Mutable) { … }

void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) { … }

void Sema::ActOnLambdaExplicitTemplateParameterList(
    LambdaIntroducer &Intro, SourceLocation LAngleLoc,
    ArrayRef<NamedDecl *> TParams, SourceLocation RAngleLoc,
    ExprResult 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) { … }

/// 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) { … }

/// 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) { … }

/// 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) { … }

void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) { … }

QualType Sema::buildLambdaInitCaptureInitialization(
    SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
    std::optional<unsigned> NumExpansions, IdentifierInfo *Id,
    bool IsDirectInit, Expr *&Init) { … }

VarDecl *Sema::createLambdaInitCaptureVarDecl(
    SourceLocation Loc, QualType InitCaptureType, SourceLocation EllipsisLoc,
    IdentifierInfo *Id, unsigned InitStyle, Expr *Init, DeclContext *DeclCtx) { … }

void Sema::addInitCapture(LambdaScopeInfo *LSI, VarDecl *Var, bool ByRef) { … }

// Unlike getCurLambda, getCurrentLambdaScopeUnsafe doesn't
// check that the current lambda is in a consistent or fully constructed state.
static LambdaScopeInfo *getCurrentLambdaScopeUnsafe(Sema &S) { … }

static TypeSourceInfo *
getDummyLambdaType(Sema &S, SourceLocation Loc = SourceLocation()) { … }

static TypeSourceInfo *getLambdaType(Sema &S, LambdaIntroducer &Intro,
                                     Declarator &ParamInfo, Scope *CurScope,
                                     SourceLocation Loc,
                                     bool &ExplicitResultType) { … }

CXXMethodDecl *Sema::CreateLambdaCallOperator(SourceRange IntroducerRange,
                                              CXXRecordDecl *Class) { … }

void Sema::AddTemplateParametersToLambdaCallOperator(
    CXXMethodDecl *CallOperator, CXXRecordDecl *Class,
    TemplateParameterList *TemplateParams) { … }

void Sema::CompleteLambdaCallOperator(
    CXXMethodDecl *Method, SourceLocation LambdaLoc,
    SourceLocation CallOperatorLoc, Expr *TrailingRequiresClause,
    TypeSourceInfo *MethodTyInfo, ConstexprSpecKind ConstexprKind,
    StorageClass SC, ArrayRef<ParmVarDecl *> Params,
    bool HasExplicitResultType) { … }

void Sema::ActOnLambdaExpressionAfterIntroducer(LambdaIntroducer &Intro,
                                                Scope *CurrentScope) { … }

void Sema::ActOnLambdaClosureQualifiers(LambdaIntroducer &Intro,
                                        SourceLocation MutableLoc) { … }

void Sema::ActOnLambdaClosureParameters(
    Scope *LambdaScope, MutableArrayRef<DeclaratorChunk::ParamInfo> Params) { … }

void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
                                        Declarator &ParamInfo,
                                        const DeclSpec &DS) { … }

void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
                            bool IsInstantiation) { … }

template <typename Func>
static void repeatForLambdaConversionFunctionCallingConvs(
    Sema &S, const FunctionProtoType &CallOpProto, Func F) { … }

// 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) { … }

QualType Sema::getLambdaConversionFunctionResultType(
    const FunctionProtoType *CallOpProto, CallingConv CC) { … }

/// 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) { … }

/// 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) { … }

/// Add a lambda's conversion to block pointer.
static void addBlockPointerConversion(Sema &S,
                                      SourceRange IntroducerRange,
                                      CXXRecordDecl *Class,
                                      CXXMethodDecl *CallOperator) { … }

ExprResult Sema::BuildCaptureInit(const Capture &Cap,
                                  SourceLocation ImplicitCaptureLoc,
                                  bool IsOpenMPMapping) { … }

ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body) { … }

static LambdaCaptureDefault
mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) { … }

bool Sema::CaptureHasSideEffects(const Capture &From) { … }

bool Sema::DiagnoseUnusedLambdaCapture(SourceRange CaptureRange,
                                       const Capture &From) { … }

/// Create a field within the lambda class or captured statement record for the
/// given capture.
FieldDecl *Sema::BuildCaptureField(RecordDecl *RD,
                                   const sema::Capture &Capture) { … }

ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
                                 LambdaScopeInfo *LSI) { … }

ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
                                               SourceLocation ConvLocation,
                                               CXXConversionDecl *Conv,
                                               Expr *Src) { … }

static FunctionDecl *getPatternFunctionDecl(FunctionDecl *FD) { … }

Sema::LambdaScopeForCallOperatorInstantiationRAII::
    LambdaScopeForCallOperatorInstantiationRAII(
        Sema &SemaRef, FunctionDecl *FD, MultiLevelTemplateArgumentList MLTAL,
        LocalInstantiationScope &Scope, bool ShouldAddDeclsFromParentScope)
    : … { … }