Re: configuration options policy (at toplevel or only inside gcc/)?

[Ian Lance Taylor <iant at google dot com>]

Basile STARYNKEVITCH <basile@starynkevitch.net> writes:

> This makes life much simpler to me, but then I do not understand how end-
> users compiling GCC are expected to configure it. Does this mean that the
> instructions on http://gcc.gnu.org/install/configure.html are no more valid
> for that case?

Note that configure options beginning with --with and --enable are
passed from the top level configure script to the subdirectory
configure scripts.  So the user just uses all the options at the top
level, and the subdirectories will see them.

I agree that new options should only be added at the appropriate
level, but there is one disadvantage: top level configure --help will
not display them.  But then configure --help is kind of useless anyhow
since it has so much boilerplate, so this is not a significant
problem.

> At last I do not understand why the MPFR & GMP stuff which has been
> discussed a lot is not already under the above scheme? Why is it cheched at
> toplevel and not only in gcc/ ? AFAIK the #include <gmp.h> appears only in
> gcc/real.h

It's at the top level because the original implementation envisioned
support for putting MPFR and GMP in the tree, alongside of the
directories gcc, libcpp, etc.  That may still happen.

Ian