<type_traits> std::is_trivially_copyable_v returns incorrect value in the presence of conditionally enabled constructors #62555
Description
Repro:
template <bool IS_CONST>
struct MyIterator
{
constexpr MyIterator() noexcept = default;
constexpr MyIterator(const MyIterator&) = default;
constexpr MyIterator(MyIterator&&) noexcept = default;
constexpr MyIterator& operator=(const MyIterator&) = default;
constexpr MyIterator& operator=(MyIterator&&) noexcept = default;
constexpr MyIterator(const MyIterator<false>&) noexcept
requires IS_CONST
: MyIterator{}
{
}
// This works:
// template <bool IS_CONST2>
// constexpr MyIterator(const MyIterator<IS_CONST2>&) noexcept
// requires (IS_CONST and not IS_CONST2)
// : MyIterator{}
// {
// }
};
static_assert(std::is_trivially_copy_assignable_v<MyIterator<true>>);
static_assert(std::is_trivially_move_assignable_v<MyIterator<true>>);
static_assert(std::is_trivially_copy_constructible_v<MyIterator<true>>);
static_assert(std::is_trivially_move_constructible_v<MyIterator<true>>);
static_assert(std::is_standard_layout_v<MyIterator<true>>);
static_assert(std::is_trivially_destructible_v<MyIterator<true>>);
static_assert(std::is_trivially_copyable_v<MyIterator<true>>);
static_assert(std::is_trivially_copy_assignable_v<MyIterator<false>>);
static_assert(std::is_trivially_move_assignable_v<MyIterator<false>>);
static_assert(std::is_trivially_copy_constructible_v<MyIterator<false>>);
static_assert(std::is_trivially_move_constructible_v<MyIterator<false>>);
static_assert(std::is_standard_layout_v<MyIterator<false>>);
static_assert(std::is_trivially_destructible_v<MyIterator<false>>);
static_assert(std::is_trivially_copyable_v<MyIterator<false>>); // FAILS with clangThe last line fails for clang, but is accepted by msvc/gcc.
Demo: https://godbolt.org/z/7sWPh5xYG
The alternative of using a template parameter that is constrained to be false instead of hard-coding false (see commented-out code) works.