MPI_Comm_f2c(3) on Linux
The text ca69c53352e7, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
Convert a communicator handle from its Fortran representation to its C representation