Re: gnulib does not always detect need for iconv() hack on musl

[Sergei Trofimovich <slyich@gmail.com>]

On Sun, Oct 17, 2021 at 07:18:51PM +0200, Bruno Haible wrote:
> Hello Sergei,
> 
> Sergei Trofimovich wrote:
> > The following fails bison-3.8.2 tests:
> >     $ ./configure && make && make check
> > The following succeeds:
> >     $ ./configure --host=x86_64-unknown-linux-musl && make && make check
> > 
> > The failure happens due to unexpected '*' output in report logs instead
> > of '%empty' on 'ASCII' locales.
> > 
> > These unexpected '*' pop back again because gnulib relies on '--host='
> > parameter for './configure' to detect musl target (for lack of better
> > signal?):
> > 
> >   https://git.savannah.gnu.org/cgit/gnulib.git/tree/m4/musl.m4#n16
> > 
> >     case "$host_os" in
> >       *-musl*) AC_DEFINE([MUSL_LIBC], [1], [Define to 1 on musl libc.]) ;;
> > 
> >   https://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/unicodeio.c#n151
> > 
> >     /* FreeBSD iconv(), NetBSD iconv(), and Solaris 11 iconv() insert
> >        a '?' if they cannot convert.  */
> >     # if !defined _LIBICONV_VERSION
> >               || (res > 0 && outptr - outbuf == 1 && *outbuf == '?')
> >     # endif
> >       /* musl libc iconv() inserts a '*' if it cannot convert.  */
> >     # if !defined _LIBICONV_VERSION && MUSL_LIBC
> >               || (res > 0 && outptr - outbuf == 1 && *outbuf == '*')
> >     # endif
> >          )
> >         return failure (code, NULL, callback_arg);
> > 
> > What do you think of enabling the workaround regardless of MUSL_LIBC
> > define?
> 
> The MUSL_LIBC symbol is supposed to be set on musl platforms; this is
> what musl.m4 is for. The difference between your two invocations is that
> in the first case, it used a $host triple inferred by config.guess,
> while in the second case, it used the $host that you specified on the
> command line.
> 
> When I try your two commands (just the configure step), the first one
> prints
>   checking for host system type... x86_64-pc-linux-musl
> while the second one prints
>   checking for host system type... x86_64-unknown-linux-musl
> 
> The next steps of the investigation are: In the first case,
>   - What did the "checking for host system type..." line look like?
>   - Which of the environment variables CC_FOR_BUILD, HOST_CC, CC,
>     CONFIG_SITE did you have defined, and to which values?

Aha, 'config.guess' clearly detects wrong libc here:

  checking build system type... x86_64-pc-linux-gnu
  checking host system type... x86_64-pc-linux-gnu

I did not realize 'config.guess' has the code to detect libc but it
clearly does. I'll dig from there and complain elsewhere.

Thank you!

-- 

  Sergei