// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "member_pointer_traits.h"

#include <type_traits>

#include <gtest/gtest.h>

namespace bt_lib_cpp_type {
namespace {

TEST(TypeTest, MemberPointerTraits) {
  struct Foo {
    bool scalar_bool_member;
    double scalar_double_member;
    double array_double_member[1];
    struct InnerStruct {
      int nested_scalar_int_member;
    } struct_member;
  };

  static_assert(std::is_same_v<Foo, MemberPointerTraits<&Foo::scalar_bool_member>::ClassType>);
  static_assert(std::is_same_v<Foo, MemberPointerTraits<&Foo::scalar_double_member>::ClassType>);
  static_assert(std::is_same_v<Foo, MemberPointerTraits<&Foo::array_double_member>::ClassType>);
  static_assert(std::is_same_v<Foo, MemberPointerTraits<&Foo::struct_member>::ClassType>);
  static_assert(
      std::is_same_v<Foo::InnerStruct,
                     MemberPointerTraits<&Foo::InnerStruct::nested_scalar_int_member>::ClassType>);

  static_assert(std::is_same_v<bool, MemberPointerTraits<&Foo::scalar_bool_member>::MemberType>);
  static_assert(
      std::is_same_v<double, MemberPointerTraits<&Foo::scalar_double_member>::MemberType>);
  static_assert(
      std::is_same_v<double[1], MemberPointerTraits<&Foo::array_double_member>::MemberType>);
  static_assert(
      std::is_same_v<Foo::InnerStruct, MemberPointerTraits<&Foo::struct_member>::MemberType>);
  static_assert(
      std::is_same_v<int,
                     MemberPointerTraits<&Foo::InnerStruct::nested_scalar_int_member>::MemberType>);

  EXPECT_EQ(offsetof(Foo, scalar_bool_member),
            MemberPointerTraits<&Foo::scalar_bool_member>::offset());
  EXPECT_EQ(offsetof(Foo, scalar_double_member),
            MemberPointerTraits<&Foo::scalar_double_member>::offset());
  EXPECT_EQ(offsetof(Foo, array_double_member),
            MemberPointerTraits<&Foo::array_double_member>::offset());
  EXPECT_EQ(offsetof(Foo, struct_member), MemberPointerTraits<&Foo::struct_member>::offset());

  // offsetof can be used with non-anonymous nested members because it refers to member identifiers,
  // not types.
  EXPECT_LT(0U, offsetof(Foo, struct_member.nested_scalar_int_member));

  // |Foo::InnerStruct| is the qualified name of a type so |nested_scalar_int_member|'s offset
  // within it is 0.
  EXPECT_EQ(0U, MemberPointerTraits<&Foo::InnerStruct::nested_scalar_int_member>::offset());
}

}  // namespace
}  // namespace bt_lib_cpp_type