top-level configure options, --help

[NightStrike]

On 1/6/08, Brian Dessent <brian@dessent.net> wrote:
> The real solution is supposed to be --help=recursive which in a normal
> autoconf project runs the --help in the top dir and then the --help of
> each existing subdir's configure.  But for whatever reason, this has
> never worked with the src/gcc toplevel configure, which is a shame
> because the number of options that are specific to various subdirs (i.e.
> not listed by the toplevel configure) is quite large.  But it's simple
> enough just to tell users to run e.g. gcc/configure --help or
> libstdc++-v3/configure --help or whatever until somebody fixes
> --help=recursive.

Ah, thank you for this.  Where is this recursive help documented?