hx freezes with 100% CPU use editing a specific Elm file

[jhbrown-veradept]

Summary

Problem: hx freezes with 100% CPU use when I try to edit a specific Elm file. I have to kill the process manually.

Reproduction Steps

1. Save the Elm code below to a file named Bogus.elm.
2. Invoke hx Bogus.elm
3. Press i to enter insert mode
4. Type a few characters. hx will freeze.

(I have reduced the original file to this self-contained demo file. Reducing the file complexity further seems to make the freezing problem go away.)

module Bogus exposing (..)

import NotRealThing as El


type alias Model =
    { state : State
    }


type State
    = State (Result Err Data)


view shared model =
    case model.state of
        State outcome ->
            case outcome of
                Ok _ ->
                    [ El.text "Success!" ]

                Err (SubErr SubErrType) ->
                    [ El.text "Specific failure already in use" ]

                Err e ->
                    [ El.text "general failure" ]

Helix log

Log from running with -vvv attached
helix.log

Platform

MacOS 12.4 (21F79) Mac M1 Arm

Terminal Emulator

iterm2 3.4.16, and Mac Terminal 2.12.7 (445)

Helix Version

22.05-218-gb6122110

[jhbrown-veradept]

elm-language-server version info:

 npm ls -g
npm WARN config global `--global`, `--local` are deprecated. Use `--location=global` instead.
/Users/jhbrown/.nvm/versions/node/v16.15.1/lib
├── @elm-tooling/elm-language-server@2.4.1
├── corepack@0.10.0
└── npm@8.11.0

[SiriusStarr]

Cannot replicate this with helix 22.05 (27609f50), can replicate with master; currently git bisecting, but my computer builds very slowly... 😆

[SiriusStarr]

Okay, bisect done, this was introduced by bumping tree-sitter in fd644cc So maybe an infinite loop in https://github.com/elm-tooling/tree-sitter-elm that showed up with the new tree-sitter version?

[SiriusStarr]

Building with

[[package]]
name = "tree-sitter"
version = "0.20.7"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "549a9faf45679ad50b7f603253635598cf5e007d8ceb806a23f95355938f76a0"

solves the problem, so it was introduced in v0.20.8.

[SiriusStarr]

Poking around upstream, another bisect shows that tree-sitter/tree-sitter@d223a81 (between v0.20.7 and v0.20.8) breaks 3 tests in https://github.com/elm-tooling/tree-sitter-elm so it's possible that that is the offending commit, though I haven't been able to find any sort of infinite loop or anything playing around with tree-sitter outside of helix.

[archseer]

I'd recommend also opening an issue upstream and link to this tracking issue.