https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111639
--- Comment #9 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> since float, double and long double all seem to be the same size on avr
Not necessarily. Since GCC v10, the default for long double is 64 bit (IEEE
double), but [long] double is also switchable per -m[long-]double={32,64}.
https://gcc.gnu.org/gcc-10/changes.html#avr
https://gcc.gnu.org/onlinedocs/gcc-14.1.0/gcc/AVR-Options.html#index-mdouble
