[Bug c++/64232] Derived class with implicitly declared assignment operator is std::is_assignable though base class is not std::is_assignable

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64232

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Not just GCC, but clang/libc++ gives the same results.