Richard Sandiford writes: Thanks much for reviewing this series. I really appreciate it. > should there be a default case that raises an error for unrecognised > libcs? Command-line checking for configure isn't very tight, but we > do raise similar errors for things like invalid --enable-threads > values. Good thinking. It's way to easy to introduce a typo somewhere and have it get missed. > On balance I think it would be better to accept > --with-default-libc=newlib but set default_libc to the empty string. That also makes good sense -- leave existing configurations unchanged. > - Should we raise an error for toolchains that don't support the given > C library? It feels like we should, but I realise that could be > difficult to do. That would be nice, but it also feels like making it reliable enough to be useful would be difficult to maintain in the future, even if we did manage to make it mostly work today. > - Very minor, but in lines like: > > +#if defined(DEFAULT_LIBC) && defined(LIBC_PICOLIBC) && DEFAULT_LIBC == LIBC_PICOLIBC > > is LIBC_PICOLIB ever undefined? It looks like config.gcc provides > an unconditional definition. If it is always defined then: > > #if DEFAULT_LIBC == LIBC_PICOLIB > > would be clearer. Agreed. Thanks again for taking a look; I'll send a new series with these issues fixed shortly. -- -keith