zero elapsed time in history with certain preexec functions

[Michael Kaminsky <kaminsky@csail.mit.edu>]

I sent this message to zsh-users in August, but didn't see any response.
In case it fell through the cracks, I'm re-sending to zsh-workers.  Can
anyone say if this is a bug?  Is there a fix or work-around?

Note:  I re-tested everything below with "zsh -f" and the behavior is the
same.  After "zsh -f" you need to "setopt" the options list in the first
example: extendedhistory histignoredups histignorespace histnostore.

Please CC me on any responses as I'm not on the list.

Thanks,

Michael

-------------------------------------------------

I use zsh's preexec function to set the title of my terminal, similar to
many of the examples posted online.  After defining preexec, however, I
noticed that zsh wasn't recording the duration of commands anymore.
After much experimentation, I believe I've come up some simple examples
to illustrate this behavior:

   $ zsh --version
   zsh 4.3.4 (i686-pc-linux-gnu)
   $ setopt|grep hist
   extendedhistory
   histignoredups
   histignorespace
   histnostore
   $ unfunction preexec
   $ sleep 2
   $ fc -ldD |tail -1
   12004  11:16  0:02  sleep 2

(so far, so good)

   $ function preexec { echo $ZSH_VERSION }
   $ sleep 2
   4.3.4
   $ fc -ldD |tail -1
   4.3.4
   12014  11:18  0:02  sleep 2

(still good, but...)

   $ function preexec { echo $ZSH_VERSION[1] }
   4.3.4
   $ sleep 2
   4
   $ fc -ldD |tail -1
   4
   12016  11:20  0:00  sleep 2

It appears that subscripting a variable (or indexing into a zsh array)
inside of the preexec function causes zsh not to record the elapsed
time/duration of the command.  There may be other actions that trigger
this behavior.  Another quick example:

   $ function preexec() { echo $1 }
   $ sleep 2
   sleep 2
   $ fc -ldD |tail -1
   fc -ldD |tail -1
   12040  11:25  0:02  sleep 2

(but...)

   $ function preexec() { echo ${(z)1} }
   function preexec() { echo ${(z)1} }
   $ sleep 2
   sleep 2
   $ fc -ldD |tail -1
   fc -ldD | tail -1
   12044  11:27  0:00  sleep 2


Any ideas?

Michael