Re: diff.el now uses diff-mode

[Stefan Monnier <monnier@iro.umontreal.ca>]

>     I've just installed a change that makes diff.el use diff-mode.
>     It considerably simplifies the code of diff.el while at the same time
>     bringing a whole bunch of improvements to diff.el.  It's also part of the
>     effort to clear the way for the new compile.el.
> Thank you.

Note that it was mostly Daniel's work.
Also using diff-mode implies that things work differently.
I think the benefit is worth the cost.

> I'm eager to see the new compile.el installed.

Same here.

> Daniel, what obstacles still remain?

The only packages that might still suffer are tex-mode and ada-xref.
The tex-mode part is code that works very poorly as it is, so I doubt people
use it much.  I expect most people who need such feature use AUCTeX instead,
so I think it's OK to just junk it.

We may be able to implement a better replacement afterwards using the new
compile.el, actually.  But I don't think this should stop us from
installing the new compile.el.

As for ada-xref.el, I'll let Daniel explain what might be broken, because
I don't know.  It's not even clear to me whether it would be broken
or not.  Also the ada-xref.el code does some really fishy things which
might break other packages.  See the example of code I appended.
I think th best way to get this code working with the new compile.el is to
install the new code and wait for someone to complain, because I don't know
anyone who understands what bugs might be introduced.  Once/if we have an
actual bug-report we'll be better able to go about fixing things.


        Stefan


      ;;  Temporarily replaces the definition of `comint-exec' so that we
      ;;  can execute commands before running gdb.
      ;;  FIXME: This is evil and not temporary !!!  -stef
      (fset 'comint-exec
	    `(lambda (buffer name command startfile switches)
	       (let (compilation-buffer-name-function)
		 (save-excursion
		   (set 'compilation-buffer-name-function
			(lambda(x) (buffer-name buffer)))
		   (compile (ada-quote-cmd
			     (concat ,pre-cmd
				     command " "
				     (mapconcat 'identity switches " "))))))
	       ))