[Bug c++/85270] Trivial assignment operator not considered such

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85270

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=87051
   Last reconfirmed|2021-12-28 00:00:00         |2023-3-14

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This breaks std::tuple<> due to new assignment operators in C++23:

https://godbolt.org/z/9EdPrdjhW

#include <type_traits>

template <class...> struct tuple;

template <>
struct tuple<> {
    tuple() = default;
    ~tuple() = default;

    tuple(const tuple&) = default;
    tuple(tuple&&) = default;

    tuple& operator=(const tuple&) = default;
    tuple& operator=(tuple&&) = default;

    constexpr const tuple& operator=(const tuple&) const noexcept { return
*this; }
    constexpr const tuple& operator=(tuple&&) const noexcept { return *this; }
};
static_assert(std::is_trivially_destructible_v<tuple<>>);
static_assert(std::is_trivially_default_constructible_v<tuple<>>);
static_assert(std::is_trivially_copy_constructible_v<tuple<>>);
static_assert(std::is_trivially_move_constructible_v<tuple<>>);
static_assert(std::is_trivially_copy_assignable_v<tuple<>>);
static_assert(std::is_trivially_move_assignable_v<tuple<>>);
static_assert(!std::is_trivially_copyable_v<tuple<>>);


<source>:23:20: error: static assertion failed
   23 | static_assert(std::is_trivially_copy_assignable_v<tuple<>>);
      |               ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:24:20: error: static assertion failed
   24 | static_assert(std::is_trivially_move_assignable_v<tuple<>>);
      |               ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 1