Re: libstdc++/3443: target CONFIG_SITE

["Golubev I. N." <gin at mo dot msk dot ru>]

I shall give more detail about `libtool' configuration for target
module (such as `libstdc++-3').  Sometimes `libtool' configuration
algorithm as in bundled `configure' is not sufficient.  For example,
it does not compute $lt_cv_cc_needs_belf or $ac_cv_func_dlopen
correctly.  Rerunning `autoconf' with updated libtool macros is not
always acceptable.

In most other packages using libtool there exists a simple
work-around: put right assignments of vars in question in one of files
enumerated in $CONFIG_SITE (see autoconf documentation about this
environment var).

$CONFIG_SITE also may contain many other things, e. g., CPPFLAGS or
CFLAGS assignments.  So to `config.status --r' in build dir correctly,
you do not need to set all of those vars explicitly.  You just need to
ensure right $CONFIG_SITE value.

And currently such a convenience is totally disabled in gcc.

When you build cross compiler, right `configure' settings for target
modules may certainly be not the same as for native ones.  But this
should not be done by switching $CONFIG_SITE off completely.  We might
have some hints in it even for code intended to work on target.
Perhaps some environment var should say that we are configuring to run
on target, not on native system.