bug#14603: 24.3.50; Error while bootstrapping Emacs on Windows

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Cc: Dmitry Gutov <dgutov@yandex.ru>,  14603@debbugs.gnu.org
> Date: Thu, 13 Jun 2013 12:15:00 -0400
> 
> Eli Zaretskii wrote:
> 
> >> No arguments, just ./configure
> >
> > That will never work. 
> 
> Can you make it detect someone has done that and throw an error?

I don't know what to detect.  Looking at $0 is not going to fit the
bill, because it is quite alright to set CONFIG_SITE manually before
invoking ./configure.  You will see that the top-level Makefile.in
does precisely that, when it finds it needs to re-run configure.
Moreover, someone might even copy mingw-cfg.site to
$prefix/share/config.site, and I don't think they deserve to be
punished by throwing an error.  So testing that "$CONFIG_SITE" is
non-empty is also sub-optimal if not outright wrong.

I wrote detailed instructions in nt/INSTALL.MSYS so that people would
know how to avoid these.  If they don't follow, they will realize that
soon enough...

> Naively, I would expect quite a lot of people to do that

I would expect them to read the instructions first.  Maybe it's me who
is naive.

> maybe it's common knowledge

It isn't.