Disabling dynamic update due to error: circular-list

[kurnevsky]

Sometimes I get this error when both ido-ubiquitous-mode and flx-ido-mode are active:

Warning (ido-cr+): Disabling dynamic update due to error: (circular-list (...

The best way to reproduce - describe function with "C-h f", enter some letters to flx start working (like "aaa") and then type left/right multiple times with any order (it uses ido-prev-match/ido-next-match).

Here is my full emacs config if anything: https://github.com/kurnevsky/dotfiles/blob/master/.emacs.d/init.el

[phst]

I've also seen this, it seems to be new in Emacs 26. I couldn't debug it though – whenever I use debug-on-error the debugger hangs when triggering the issue (potentially due to the circular list).

[DarwinAwardWinner]

Does ido continue to function after seeing that warning, or does it actually throw an error after that?

[DarwinAwardWinner]

As for what could be causing it, my guess is that both ido-cr+ and flx-ido are mutating the completion list in place, and both of them are assuming that they are the only one doing so. The easy fix is to have ido-cr+ disable flx-ido when dynamic updates are being used, but this is suboptimal because it means that ido will work differently based on the internals of which function is calling it.

[kurnevsky]

After this warning ido continue to function (without dynamic updates).

[DarwinAwardWinner]

Well, at least it's good to know that the error-catching facilities I added are working as intended.

[kurnevsky]

In case if somebody is interested - implemented workaround (turning off flx-ido-mode) for my config: https://github.com/kurnevsky/dotfiles/commit/b4daed5ea3d554b816767dbb1284bf5ea7e82de9

[DarwinAwardWinner]

Wow, add-variable-watcher looks like a really useful addition to Emacs 26. If everyone is sure that this is only a problem that occurs in Emacs 26, I can go ahead and put this fix directly into ido-cr+.

[DarwinAwardWinner]

By the way, can I ask why you're adding save-buffer to the function blacklist? I don't think that function should involve ido-cr+ at all.

[kurnevsky]

Sure, I have function to create new empty buffer: https://github.com/kurnevsky/dotfiles/blob/master/.emacs.d/init.el#L627 and when I save it with save-buffer it asks file name (emacs uses read-file-name inside basic-save-buffer function which is called from save-buffer). If ido is enabled it suggests only existent files, so I have to disable ido to type a new file name.

[kurnevsky]

If everyone is sure that this is only a problem that occurs in Emacs 26, I can go ahead and put this fix directly into ido-cr+.

Actually I didn't try to reproduce with emacs 25. But I've seen this in both 26 and 27 versions.

[DarwinAwardWinner]

Ido-cr+ has nothing to do with file completion, so I don't think adding save-buffer to the ido-cr+ blacklist would have any effect. You would want to disable ido-mode for that function, not ido-ubiquitous-mode.

[DarwinAwardWinner]

Anyway, as for fixing this issue properly, it will have to wait until Emacs 26 is released and I upgrade to it, or until they fix some issues preventing testing with Emacs 26 on Travis: https://github.com/cask/cask/issues/417

[kurnevsky]

Hm, indeed, it doesn't change anything. I added this when moved from helm to ido-cr+, because helm-mode affects read-file-name function as well (and it has similar blacklist). Perhaps I was misled when activated helm-mode and saw similar behaviour :)

[DarwinAwardWinner]

This should be fully fixed by 6861547.

[kurnevsky]

@DarwinAwardWinner does it mean that this workaround can be removed?

[DarwinAwardWinner]

Possibly. I'll have to check. Thanks for the reminder.