[Bug fortran/88579] Calculating power of powers of two

[anlauf at gmx dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88579

--- Comment #4 from Harald Anlauf <anlauf at gmx dot de> ---
Patch submitted here:

https://gcc.gnu.org/ml/fortran/2019-01/msg00163.html