Date: Mon, 30 Dec 2002 20:51:36 +0300
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
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To: rich AT phekda DOT freeserve DOT co DOT uk
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In-reply-to: <3E1029E3.E679E723@phekda.freeserve.co.uk> (message from Richard
	Dawe on Mon, 30 Dec 2002 11:11:31 +0000)
Subject: Re: <sys/config.h>
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> Date: Mon, 30 Dec 2002 11:11:31 +0000
> From: Richard Dawe <rich AT phekda DOT freeserve DOT co DOT uk>
> 
> "/* config.h for DJGPP.
> 
>    This is usually generated automatically from config.h.in by the
>    configure script.  However, it is very hard to run that script under
>    MS-DOS, because of its extensive use of Unix shell features.  This
>    header file is provided so you can skip the autoconfigure step
>    altogether and go directly to the compilation step (after copying
>    Makefile.in to Makefile and setting the defaults there).
> 
>    There are several parts in this header file, which closely follow the
>    GNU Autoconf procedures."
> 
> (Rest of description omitted.)
> 
> I can see that this script was useful in earlier days, but why do we have it
> now? configure scripts run just fine now.

Emacs is traditionally built by running config.bat, not its Unix
configure script.  config.bat edits config.in and Makefile.in files
using a few Sed scripts in the `msdos' subdirectory (which see).

While moving to the configure script might be a Good Thing, it also
has some downsides (apart of the obvious one: the need to invest the
effort to make configure run on DJGPP platforms).  The most important
consideration is that Emacs is one of the few ``basic tools'' (which
include Make) that could benefit from the fact that you don't need too
many non-standard tools, let alone a fully operational DJGPP
installation, to build them.

> This header could be a maintenance problem.

In practice, it isn't.  We don't change anything in sys/config.h for a
long time.  It's a matter of relatively simple comparison and adding a
few lines to msdos/sed*.inp, to have a new release of Emacs build with
DJGPP.

Note that Emacs is not completely autoconfiscated yet; there are
headers like src/m/i386.h and src/s/msdos.h that are maintained
manually.