SemaTemplateDeductionGuide.cpp | Explore in Territory

//===- SemaTemplateDeductionGude.cpp - Template Argument Deduction---------===//
//
// 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 deduction guides for C++ class template argument
// deduction.
//
//===----------------------------------------------------------------------===//

#include "TreeTransform.h"
#include "TypeLocBuilder.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclFriend.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclarationName.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/OperationKinds.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/TemplateBase.h"
#include "clang/AST/TemplateName.h"
#include "clang/AST/Type.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Basic/TypeTraits.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/Overload.h"
#include "clang/Sema/Ownership.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/Template.h"
#include "clang/Sema/TemplateDeduction.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
#include <cassert>
#include <optional>
#include <utility>

usingnamespaceclang;
usingnamespacesema;

namespace {
/// Tree transform to "extract" a transformed type from a class template's
/// constructor to a deduction guide.
class ExtractTypeForDeductionGuide
    : public TreeTransform<ExtractTypeForDeductionGuide> { … };

// Build a deduction guide using the provided information.
//
// A deduction guide can be either a template or a non-template function
// declaration. If \p TemplateParams is null, a non-template function
// declaration will be created.
NamedDecl *buildDeductionGuide(
    Sema &SemaRef, TemplateDecl *OriginalTemplate,
    TemplateParameterList *TemplateParams, CXXConstructorDecl *Ctor,
    ExplicitSpecifier ES, TypeSourceInfo *TInfo, SourceLocation LocStart,
    SourceLocation Loc, SourceLocation LocEnd, bool IsImplicit,
    llvm::ArrayRef<TypedefNameDecl *> MaterializedTypedefs = { … }

// Transform a given template type parameter `TTP`.
TemplateTypeParmDecl *transformTemplateTypeParam(
    Sema &SemaRef, DeclContext *DC, TemplateTypeParmDecl *TTP,
    MultiLevelTemplateArgumentList &Args, unsigned NewDepth, unsigned NewIndex,
    bool EvaluateConstraint) { … }
// Similar to above, but for non-type template or template template parameters.
template <typename NonTypeTemplateOrTemplateTemplateParmDecl>
NonTypeTemplateOrTemplateTemplateParmDecl *
transformTemplateParam(Sema &SemaRef, DeclContext *DC,
                       NonTypeTemplateOrTemplateTemplateParmDecl *OldParam,
                       MultiLevelTemplateArgumentList &Args, unsigned NewIndex,
                       unsigned NewDepth) { … }

NamedDecl *transformTemplateParameter(Sema &SemaRef, DeclContext *DC,
                                      NamedDecl *TemplateParam,
                                      MultiLevelTemplateArgumentList &Args,
                                      unsigned NewIndex, unsigned NewDepth,
                                      bool EvaluateConstraint = true) { … }

/// Transform to convert portions of a constructor declaration into the
/// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
struct ConvertConstructorToDeductionGuideTransform { … };

// Find all template parameters that appear in the given DeducedArgs.
// Return the indices of the template parameters in the TemplateParams.
SmallVector<unsigned> TemplateParamsReferencedInTemplateArgumentList(
    const TemplateParameterList *TemplateParamsList,
    ArrayRef<TemplateArgument> DeducedArgs) { … }

bool hasDeclaredDeductionGuides(DeclarationName Name, DeclContext *DC) { … }

// Build the associated constraints for the alias deduction guides.
// C++ [over.match.class.deduct]p3.3:
//   The associated constraints ([temp.constr.decl]) are the conjunction of the
//   associated constraints of g and a constraint that is satisfied if and only
//   if the arguments of A are deducible (see below) from the return type.
//
// The return result is expected to be the require-clause for the synthesized
// alias deduction guide.
Expr *
buildAssociatedConstraints(Sema &SemaRef, FunctionTemplateDecl *F,
                           TypeAliasTemplateDecl *AliasTemplate,
                           ArrayRef<DeducedTemplateArgument> DeduceResults,
                           unsigned FirstUndeducedParamIdx, Expr *IsDeducible) { … }
// Build the is_deducible constraint for the alias deduction guides.
// [over.match.class.deduct]p3.3:
//    ... and a constraint that is satisfied if and only if the arguments
//    of A are deducible (see below) from the return type.
Expr *buildIsDeducibleConstraint(Sema &SemaRef,
                                 TypeAliasTemplateDecl *AliasTemplate,
                                 QualType ReturnType,
                                 SmallVector<NamedDecl *> TemplateParams) { … }

std::pair<TemplateDecl *, llvm::ArrayRef<TemplateArgument>>
getRHSTemplateDeclAndArgs(Sema &SemaRef, TypeAliasTemplateDecl *AliasTemplate) { … }

// Build deduction guides for a type alias template from the given underlying
// deduction guide F.
FunctionTemplateDecl *
BuildDeductionGuideForTypeAlias(Sema &SemaRef,
                                TypeAliasTemplateDecl *AliasTemplate,
                                FunctionTemplateDecl *F, SourceLocation Loc) { … }

void DeclareImplicitDeductionGuidesForTypeAlias(
    Sema &SemaRef, TypeAliasTemplateDecl *AliasTemplate, SourceLocation Loc) { … }

// Build an aggregate deduction guide for a type alias template.
FunctionTemplateDecl *DeclareAggregateDeductionGuideForTypeAlias(
    Sema &SemaRef, TypeAliasTemplateDecl *AliasTemplate,
    MutableArrayRef<QualType> ParamTypes, SourceLocation Loc) { … }

} // namespace

FunctionTemplateDecl *Sema::DeclareAggregateDeductionGuideFromInitList(
    TemplateDecl *Template, MutableArrayRef<QualType> ParamTypes,
    SourceLocation Loc) { … }

void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,
                                          SourceLocation Loc) { … }
llvm/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
