10.44.2 stdc_bit_floor

Documentation:
ISO C23 (latest free draft https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf) section 7.18.15.

Gnulib module: stdc_bit_floor

Portability problems fixed by Gnulib:

Portability problems not fixed by Gnulib: