Helix crashed on "Undo change" (u) [undo]

[souserge]

Summary

I had an opened JS file in helix. I accidentally pasted some text from the system clipboard several times by making a three-finger gesture swiping from right to left (the pasting action is probably due to me using tmux). I pressed 'u' to undo it and it said "Already at oldest change". After pressing Escape, I could undo the change but after pressing it a few times, Helix crashed with the error message presented in the Helix log. I may have tried writing the file with :w (don't remember exactly).

Additionally, I have the JavaScript language server running, and auto-format using prettier.

Reproduction Steps

I tried this:

1. tmux
2. hx file.js
3. paste something form the system's clipboard.
4. press u
5. press <Esc>
6. press u a few times
7. press :w

I expected this to happen:

Changes are undone and the file is saved with formatting

Instead, this happened:

The editor has crashed.

Helix log

No related logs were recorded but the program crashed with the following error outputed to the terminal:

thread 'main' panicked at 'assertion failed: original_doc.len_chars() == self.len', helix-core/src/transaction.rs:265:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Platform

Linux (Fedora 37)

Terminal Emulator

alacritty 0.10.1

Helix Version

helix 22.12

[pascalkuthe]

A bit of a longshot but the problem maybe fixed by #5711 if your file contains any non-ascii chars. Could you try again with that PR? Otherwise please post your file with which you experienced the crash so we can reproduce and test the problem ourselfs.

[gabydd]

#1410 has the same panic, it seems to have to do with paste and then undo

[pascalkuthe]

#1410 has the same panic, it seems to have to do with paste and then undo

Any kind of incorrect transaction applied to a document can cause crashes like these. A ton of different bugs can cause incorrect transactions to be produced so the panic message doesn't tell us much about the cause. Since #1410 was reported most of these issues have been fixed (many by @the-mikedavis). So this is likely a different bug. It sounds like it's LSP related hence I suggested #5711 since I had similar crashes while testing that (before I finally fixed them all)

[the-mikedavis]

I can't reproduce this with just those steps: can you reliably reproduce this with some exact clipboard contents? If you can reproduce could you capture the full backtrace by setting RUST_BACKTRACE=1?

Also: do you have a language server installed for javascript and have you configured it to format on save?

[pascalkuthe]

Also: do you have a language server installed for javascript and have you configured it to format on save?

I think he does, from the issue description:

Additionally, I have the JavaScript language server running, and auto-format using prettier.

Which reminded me of #4791 (hence my guess that #5711 may fix this)

[archseer]

I had a similar crash lately, it happened when I was pasting via middle click (and I might have been in insert mode?) then undo. It was a Go file in my case

[souserge]

@pascalkuthe @the-mikedavis I'm not sure if I reproduced the same bug I had last time, since now the panic output looks different. Nevertheless, the circumstances are very similar so it's probably caused by the same issue.

Some observations

• The bug also appears with no user configuration file present (vanilla Helix settings).
• I could not replicate it when having the mouse disabled via the config.toml --> [editor] --> mouse property.
• It probably has to do with the LSP since I wasn't able to achieve the same error when the result of the pasting was valid JS code, or when I renamed the file to testHelixBug.txt. Since I was able to replicate it without saving, I think auto-format here is not involved.
• It doesn't seem to depend on the shell (tried bash, zsh, and fish) or the terminal emulator (tried with alacritty, tilix, and the default GNOME terminal). Also tmux doesn't influence the result. I was able to replicate it in all cases (For the record, I haven't tried all possible combinations though).

Environment:

• Fedora 37 running on Lenovo ThinkPad E590
• Node v19.4.0 (installed via nvm v2.2.11)
• Globally installed [email protected]
• Helix editor version 22.12 (installed via the COPR dnf package varlad/helix)
• JavaScript LSP set up (green tick box in hx --heath)
• No user configuration. Specifically, [editor] --> mouse NOT set to false

Steps to replicate

(I also recorded it using asciinema).

1. create a JS file (e.g. testHelixbug.js) with the following contents:

// Make sure the mouse isn't disabled (editor.mouse in config.toml)
// Steps to reproduce:
//   * Click on the last line (marked with tilde)
//   * Press: <middle-click> <middle-click> <middle-click> u <middle-click> u

function test() {
  return "Hello, world!";
}

2. Copy the following text to your system clipboard: helix editor
3. Open the file: $ RUST_BACKTRACE=full hx testHelixBug.js
4. Click somewhere on the last line (should be marked with a tilda) with a mouse. You don't need to actually click it as long as you have the cursor there.
5. Press: <middle-click> <middle-click> <middle-click> u <middle-click> u
6. Observe the crash (Position and len might differ):

thread 'main' panicked at 'Position 307 is out of range for changeset len 302!', helix-core/src/transaction.rs:397:13
stack backtrace:
   0:     0x558872968465 - <unknown>
   1:     0x5588720489ae - <unknown>
   2:     0x558872962105 - <unknown>
   3:     0x558872969de3 - <unknown>
   4:     0x558872969aef - <unknown>
   5:     0x55887296a4af - <unknown>
   6:     0x55887296a314 - <unknown>
   7:     0x55887296896c - <unknown>
   8:     0x55887296a062 - <unknown>
   9:     0x558871fb5e43 - <unknown>
  10:     0x558872158572 - <unknown>
  11:     0x558872712a8f - <unknown>
  12:     0x558872714034 - <unknown>
  13:     0x558872608159 - <unknown>
  14:     0x55887248e646 - <unknown>
  15:     0x55887248e56e - <unknown>
  16:     0x558872490e5b - <unknown>
  17:     0x5588725c7845 - <unknown>
  18:     0x5588727afcc7 - <unknown>
  19:     0x5588727d058f - <unknown>
  20:     0x558872809a79 - <unknown>
  21:     0x55887282aa70 - <unknown>
  22:     0x5588727d1301 - <unknown>
  23:     0x5588728110f3 - <unknown>
  24:     0x5588728215f9 - <unknown>
  25:     0x55887295d6ba - <unknown>
  26:     0x5588727d1408 - <unknown>
  27:     0x7f5558d05510 - __libc_start_call_main
  28:     0x7f5558d055c9 - __libc_start_main@GLIBC_2.2.5
  29:     0x558871ff21d5 - <unknown>
  30:                0x0 - <unknown>

[pascalkuthe]

Thank you so much for following up on this! I can reproduce this easily on the latest master and am looking into a fix. Detail reproduction cases like this are greatly appreciated. Not LSP related tough as this also occurs with :language text

[pascalkuthe]

turns out all paste commands don't append to history when called as a typable commands (which is a well known cause of crashes in combination with undo). Middle mouse just call :clipboard-paste-before, the same crash can also be reproduced by just using the typable command directly. #5790 fixes the problem

[scimas]

I have managed to get a panic very similar to this issue.

thread 'main' panicked at D:\a\helix\helix\helix-core\src\transaction.rs:461:9:
Positions [(8682, After)] are out of range for changeset len 8674!
note: run with `RUST...

Happened on an undo after a clipboard-paste-replace. I didn't open a new issue because I don't have reproduction steps.