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From: Bart Schaefer <schaefer@brasslantern.com>
To: Zsh hackers list <zsh-workers@zsh.org>
Subject: Bug: function calls with break in preexec
Date: Sat, 16 Sep 2023 08:08:12 -0700	[thread overview]
Message-ID: <CAH+w=7ZLvbJadBMgKrnMZZr70B55jjK0vkE=0LVNZgyi+H8hnQ@mail.gmail.com> (raw)

This nofork test is what got me here:

  repeat 3 do purr ${
   for x in 1 2 3 4
   do (( x == 3 )) && break 2; print $x
   } XX

This fails when added to the test suite because it produces no output at all.

"purr" is a function:
  purr() { print -r -- "$@" }

If "purr" is replaced by "print -r --" in the repeat loop, everything
works as expected, the output is

2 XX

Its important that the ${ ... } is expanded by preexec() before the
function is called.  After scratching my head for a while I came up
with a way to have that happen even without the nofork patches:

  repeat 3 print c*(oe:'break':)

prints all the files starting with "c" (e.g., run it in the zsh source
tree) but only once.  Conversely,

  repeat 3 purr c*(oe:'break':)

prints nothing.  "set -x" shows the function call being made, but it
immediately stops without executing any commands.

One of these cases has to be wrong:  Either the loop should break
immediately, so neither the builtin nor the function runs, or the
function should run and then the loop should break.  Or more
radically, a break occurring in the argument expansions should just be
discarded, but that seems wrong too.  I think it's the former:  The
builtin shouldn't run in this case.

                 reply	other threads:[~2023-09-16 15:09 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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