Run coc.nvim on Bun, and failed

[jackielii]

Hi,

Since bun has caught quite a bit of attention, I figured why not try running coc.nvim using Bun? And here is the journey and spoilers: I failed

I started with bun esbuild.js. It obviously worked because it just uses esbuild. However, since bun's build API is borrowed from esbuild, so making a bunbuild.js is simple enough and it also worked.

So that was a good start. Next let's run the bundled js directly with bun build/index.js, and there is our first error:

The code is inside factory.ts and reading through it, this is the extension loading mechanism. It uses Node's internal Module._compile API, in the newest version, it lives under lib/internal/modules/cjs/loader.js. Although depending on an internal API is not very good, but it seems others does the same: jsonpath.

OK, I was about to give up: Bun says it's compatible with Node, with lots of asterisks. Understandably this is not public API since it's prefixed with _. But just as I was moving away from it and refresh the page. The issue got closed by a PR that adds the _compile method: oven-sh/bun#5840! Feeling rather lucky, I ran bun upgrade --canary, and continued...

So reading the factory.ts, it seems that the getProtoWithCompile is only used to extract the _compile method from Module so that it can be monkey patched in the createSandbox function. I don't fully get why this approach was taken. But it seems to rely on how require and _compile works internally in Nodejs's Module implementation. I don't know if this will work in Bun as Bun uses a native implementation in Zig, and it's not attached to the prototype Although this shouldn't stop us as we're not loading any extension yet. Let's just get this part happy, we won't hit it yet. To work around it, I just modify the top level ModuleProto with:

const ModuleProto = new Module('fake')

Re-run bun build/index.js now gives some text:

Since coc.nvim uses stdin and stdout to communicate with neovim, this is good news, it looks like the msgPack messages. I eagerly fired up nvim with minimal config:

set nocompatible
let g:coc_node_path = 'bun'
" let g:node_client_debug = 1
let g:coc_node_args = []
let $NODE_CLIENT_LOG_FILE = '/tmp/coc.log'
set runtimepath^=$PWD
filetype plugin indent on
syntax on
set hidden

Importantly let g:coc_node_args = [] is needed because bun doesn't have --no-warnings which is the default option added to the start up args. Then error:

At this point, I don't have any clue what is going on. So I figured I'll park this for now and share it just in case someone else find this interesting and want to continue

[chemzqm]

It's expected. An internal method of the module module is hacked to load extensions

coc.nvim/src/util/factory.ts

Line 151 in 06d5dfd

ModuleProto._compile = compileInSandbox(sandbox, cocExports)

[jackielii]

Some further findings forgot to share:

The full error message shown after running above is:

It looks like the problem lies within the neovim's node-client. So I used this program to check (borrowed from neovim node-client):

const cp = require('child_process')
const attach = require('neovim').attach // replaced neovim with @chemzqm/neovim to cross check

const nvim_proc = cp.spawn('nvim', ['-u', 'NONE', '-N', '--embed'], {})

// Attach to neovim process
;(async function () {
  const nvim = await attach({ proc: nvim_proc })
  nvim.command('vsp')
  nvim.command('vsp')
  nvim.command('vsp')
  const windows = await nvim.windows

  // expect(windows.length).toEqual(4);
  // expect(windows[0] instanceof nvim.Window).toEqual(true);
  // expect(windows[1] instanceof nvim.Window).toEqual(true);

  nvim.window = windows[2]
  const win = await nvim.window

  // expect(win).not.toEqual(windows[0]);
  // expect(win).toEqual(windows[2]);

  const buf = await nvim.buffer
  // expect(buf instanceof nvim.Buffer).toEqual(true);

  const lines = await buf.lines
  // expect(lines).toEqual(['']);

  await buf.replace(['line1', 'line2'], 0)
  const newLines = await buf.lines
  // expect(newLines).toEqual(['line1', 'line2']);

  nvim.quit()
  // nvim_proc.disconnect()
})()

So as shown above, I ran the script with neovim package and @chemzqm/neovim package, and compared the result. The neovim package exited without error, the @chemzqm/neovim package showed error:

Lastly I replaced all reference of @chemzqm/neovim to neovim, rebuilt, and re-run nvim -u mini.vim I get:

Albeit the error, checkhealth reports it's running:

Although I don't think it's actually working as none of the commands works. e.g. CocInfo

[meinzer1899]

Hey, any updates on this? bun 1.1.2 got released recently.