RE: Problem compiling Emacs 21.1 - coff.h not found in src/unexec.c on ISC 4.1a

[Andrew Wiseman]

> Could you please look into the 20.6 source directory where you built
> Emacs on that system, and post here what system configuration did the
> configure script pick up, and what header files in src/m and src/s
> did it include?  Perhaps your system was treated as a different one
> back there?

Unfortunately, after I had emacs-20.6 working I then removed all of the
distribution source to save space. (But I did leave the files that were
changed by the configure.)

However, as an experiment, I have now re-loaded the source for both 20.6
(actually 20.6.1 was the release I used) and 21.1 and have tried to
recompile both from scratch.

For both I did,

     configure --prefix=/var --with-x=no
     make -k

And in both cases, configure picked up "i386-pc-4.1a".

For emacs-20.6.1 there was a problem in sysdep.c, (I remember this from
before, and I think I reported it as a bug). I corrected this as
follows...

emacs-20.6/src/sysdep.c line 2607
changed from
     nread = (*read_socket_hook) (0, buf, 256, 1, 0);
to
     nread = (*read_socket_hook) (0, buf, 256, 1);

I then did make -k again, and emacs 20.6.1 compiled.

But back in emacs-21.1, I got the same problem as before:

     unexec.c:175: coff.h: No such file or directory

(In emacs-20.6.1, unexec.c compiled perfectly.)

Just to confirm, in both distributions, src/config.h included s/isc4-1.h
and m/intel386.h.

So it would seem that in both 20.6.1 and 21.1 on my machine, COFF is
defined to be 1. But in emacs 21.1, it is assumed in src/unexec.c that
this implies <coff.h> is present when it isn't. If my reading of
emacs-20.6/src/unexec.c is correct, <coff.h> is only included #ifdef
MSDOS.

As a wild stab in the dark, I made the following change
emacs-21.1/src/unexec.c line 175
changed from
     #include <coff.h>
to
     #include <a.out.h>

The compile then goes right through to the end, but gives this error:

     undefined                       first referenced
      symbol                             in file
     wait3                               process.o

So I thought I'd better stop tinkering there :-)

As before, any help gratefully received.

Regards,
Andrew Wiseman