timing builtins etc.

[Peter Stephenson <pws@ifh.de>]

(Thought I'd sent this:  it looks like I exited Emacs before MH
finished sending it.)

I have been working on the bug that builtins and shell functions can't
be timed.  I found a neat way of doing it which simply involved adding
the current process to the job list.  This even supplied a more
natural way of fixing the previous bug that a builtin run at the end
of the pipeline lost its status to something before.  It was all very
swish, and it works fine for builtins.

Unfortunately it doesn't work for shell functions.  The culprit is the
list_pipe code in exec.c, which randomly deletes the job from the
table and it gets used for other purposes later (you can't simply
hijack the new current job).  So the code worked where the shell
function was inside a pipe, such as `echo foo | fn', but not on its
own.

Unfortunately, too, the list_pipe code is horrendously complicated and
completely uncommented and I've never understood any of it.  Can
anybody suggest anything?  Does anybody know why it randomly deletes
jobs?  Isn't there a neater way of fixing the original problem?

I'm tempted to pretend that the code is already in a pipeline when
`time' is used.  I'm not quite sure yet what effect this will have.

-- 
Peter Stephenson <pws@ifh.de>       Tel: +49 33762 77366
WWW:  http://www.ifh.de/~pws/       Fax: +49 33762 77330
Deutches Electronen-Synchrotron --- Institut fuer Hochenergiephysik Zeuthen
DESY-IfH, 15735 Zeuthen, Germany.