TypeTraits.cpp

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//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
 
#include "TypeTraits.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include <optional>
 
namespace clang::tidy::utils::type_traits {
 
static bool classHasTrivialCopyAndDestroy(QualType Type) {
  auto *Record = Type->getAsCXXRecordDecl();
  return Record && Record->hasDefinition() &&
         !Record->hasNonTrivialCopyConstructor() &&
         !Record->hasNonTrivialDestructor();
}
 
static bool hasDeletedCopyConstructor(QualType Type) {
  auto *Record = Type->getAsCXXRecordDecl();
  if (!Record || !Record->hasDefinition())
    return false;
  for (const auto *Constructor : Record->ctors()) {
    if (Constructor->isCopyConstructor() && Constructor->isDeleted())
      return true;
  }
  return false;
}
 
std::optional<bool> isExpensiveToCopy(QualType Type,
                                      const ASTContext &Context) {
  if (Type->isDependentType() || Type->isIncompleteType())
    return std::nullopt;
  return !Type.isTriviallyCopyableType(Context) &&
         !classHasTrivialCopyAndDestroy(Type) &&
         !hasDeletedCopyConstructor(Type) && !Type->isObjCLifetimeType();
}
 
bool recordIsTriviallyDefaultConstructible(const RecordDecl &RecordDecl,
                                           const ASTContext &Context) {
  const auto *ClassDecl = dyn_cast<CXXRecordDecl>(&RecordDecl);
  // Non-C++ records are always trivially constructible.
  if (!ClassDecl)
    return true;
  // It is impossible to determine whether an ill-formed decl is trivially
  // constructible.
  if (RecordDecl.isInvalidDecl())
    return false;
  // A class with a user-provided default constructor is not trivially
  // constructible.
  if (ClassDecl->hasUserProvidedDefaultConstructor())
    return false;
  // A polymorphic class is not trivially constructible
  if (ClassDecl->isPolymorphic())
    return false;
  // A class is trivially constructible if it has a trivial default constructor.
  if (ClassDecl->hasTrivialDefaultConstructor())
    return true;
 
  // If all its fields are trivially constructible and have no default
  // initializers.
  for (const FieldDecl *Field : ClassDecl->fields()) {
    if (Field->hasInClassInitializer())
      return false;
    if (!isTriviallyDefaultConstructible(Field->getType(), Context))
      return false;
  }
  // If all its direct bases are trivially constructible.
  for (const CXXBaseSpecifier &Base : ClassDecl->bases()) {
    if (!isTriviallyDefaultConstructible(Base.getType(), Context))
      return false;
    if (Base.isVirtual())
      return false;
  }
 
  return true;
}
 
// Based on QualType::isTrivial.
bool isTriviallyDefaultConstructible(QualType Type, const ASTContext &Context) {
  if (Type.isNull())
    return false;
 
  if (Type->isArrayType())
    return isTriviallyDefaultConstructible(Context.getBaseElementType(Type),
                                           Context);
 
  // Return false for incomplete types after skipping any incomplete array
  // types which are expressly allowed by the standard and thus our API.
  if (Type->isIncompleteType())
    return false;
 
  if (Context.getLangOpts().ObjCAutoRefCount) {
    switch (Type.getObjCLifetime()) {
    case Qualifiers::OCL_ExplicitNone:
      return true;
 
    case Qualifiers::OCL_Strong:
    case Qualifiers::OCL_Weak:
    case Qualifiers::OCL_Autoreleasing:
      return false;
 
    case Qualifiers::OCL_None:
      if (Type->isObjCLifetimeType())
        return false;
      break;
    }
  }
 
  QualType CanonicalType = Type.getCanonicalType();
  if (CanonicalType->isDependentType())
    return false;
 
  // As an extension, Clang treats vector types as Scalar types.
  if (CanonicalType->isScalarType() || CanonicalType->isVectorType())
    return true;
 
  if (const auto *RD = CanonicalType->getAsRecordDecl()) {
    return recordIsTriviallyDefaultConstructible(*RD, Context);
  }
 
  // No other types can match.
  return false;
}
 
// Based on QualType::isDestructedType.
bool isTriviallyDestructible(QualType Type) {
  if (Type.isNull())
    return false;
 
  if (Type->isIncompleteType())
    return false;
 
  if (Type.getCanonicalType()->isDependentType())
    return false;
 
  return Type.isDestructedType() == QualType::DK_none;
}
 
bool hasNonTrivialMoveConstructor(QualType Type) {
  auto *Record = Type->getAsCXXRecordDecl();
  return Record && Record->hasDefinition() &&
         Record->hasNonTrivialMoveConstructor();
}
 
bool hasNonTrivialMoveAssignment(QualType Type) {
  auto *Record = Type->getAsCXXRecordDecl();
  return Record && Record->hasDefinition() &&
         Record->hasNonTrivialMoveAssignment();
}
 
} // namespace clang::tidy::utils::type_traits