vm-pipe-message-to-command gives: Command 'foo' produced no output

[John Hein]

Rev 1355 on the trunk introduced new behavior for vm-pipe-message-to-command. It produces "Command 'foo' produced no output".

Workaround: mark the message (e.g., with M M) and invoke vm-next-command-uses-marks (M N) before vm-pipe-message-to-command. That doesn't work well if you want to operate on just the current message.

[Uday Reddy (reddyuday)]

Are you sure it was in rev. 1355? I don't see any changes in 1355 that
could have caused it. Moreover, I recall seeing that message for ages, even
in Kyle Jones's releases.

Why is it a bug, anyway?

Cheers,
Uday

[John Hein (xpqheqdvq4)]

Works with 1354.
'no output' with 1355.

Manually reverting this hunk when using 1355 makes it "work" again...

<pre>
--- lisp/vm-save.el 2012-02-05 17:09:18 +0000
+++ lisp/vm-save.el 2012-02-12 20:29:09 +0000
@@ -645,7 +645,7 @@
        (pop-up-windows (and pop-up-windows (eq vm-mutable-window-configuration t)))
        ;; prefix arg doesn't have "normal" meaning here, so only call
        ;; vm-select-operable-messages for marks and threads.
- (mlist (vm-select-operable-messages 1 (vm-interactive-p) "Pipe")))
+ (mlist (vm-select-operable-messages 0 (vm-interactive-p) "Pipe")))
     (vm-retrieve-operable-messages 1 mlist)
     (save-excursion
       (set-buffer buffer)
</pre>

All the versions I've tried over the years have been happy to pipe the current message to a command. Since that's a sparse mapping, it may be that some other versions produced 'no output' but none that I recall.

[Uday Reddy (reddyuday)]

It looks like the "produced no output" message was introduced in revision
454, way back when. See vm-save.el. It is likely that it didn't fire due
to some other bug and, when that was fixed, it started firing again.

In any case, why should this message be blocked?

Cheers,
Uday

[John Hein (xpqheqdvq4)]

Sorry if I wasn't clear. It's not the message that is a problem except that it's unfortunately quite accurate. It really is producing _no output_ because, well, the command is not being invoked at all.

Try, for instance, '| | wc' to see what I mean.

[Uday Reddy (reddyuday)]

John, if you are still having this problem, can you please do M-x vm-submit-bug-report? I am not able to reproduce it.

[John Hein (xpqheqdvq4)]

Fixed somewhere between revno 1450 (has bug) & 1460 (doesn't have bug).

[John Hein (xpqheqdvq4)]

1457 has bug, 1458 doesn't

[John Hein (xpqheqdvq4)]

fixed on trunk in revno 1458

[John Hein (xpqheqdvq4)]

So it was the addition of the check for (= prefix 0) in vm-select-operable-messages in vm-folder.el (revno 1458) that fixes this bug.

[John Hein (xpqheqdvq4)]

Hmm... but now it tries to run the command many times. Still a bug, but different symptoms now.

[John Hein (xpqheqdvq4)]

Never mind, it doesn't do that behavior (running the command multiple times) in revno 1476.

[Uday Reddy (reddyuday)]

Well, it was really fixed in rev. 1461 when I did a general scan of all calls to vm-select-operable-messages.

It is firmly fixed now.