build: switch to node 20, add back loader param

[quisquous]

Instead of:
ts-node util/sync_files.ts
Now we must do:
node --loader=ts-node/esm util/sync_files.ts

This should work on both node 18 and node 20 (tested locally).

Git workflows were pinned to 18.18.2 via #5991, but are now updated to 20 for constency. It's possible that ts-node will fix this in the future and we can remove (again) the loader param.

Fixes #5910.
Fixes #5989.

[quisquous]

@xiashtra why the confused emoji?

[quisquous]

An alternative to this PR is to switch to using --loader instead of --import which will work on node 18 and node 20. However, every script run will spit out this blob of text about how we should be using --import instead.

$ npm run test

> [email protected] test
> mocha

(node:19160) ExperimentalWarning: `--experimental-loader` may be removed in the futur
e; instead use `register()`:
--import 'data:text/javascript,import { register } from "node:module"; import { pathT
oFileURL } from "node:url"; register("ts-node/esm", pathToFileURL("./"));'
(Use `node --trace-warnings ...` to show where the warning was created)

  [▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬..............]

[xiashtra]

@xiashtra why the confused emoji?

Nothing you are responsible for. I don't follow Node's development, so I'm just confused why the upstream change. It seems like a lot of tedious boilerplate just to run the utility scripts, and on top of that, if it's considered deprecated, what is the intended long-term solution?

[quisquous]

@xiashtra why the confused emoji?

Nothing you are responsible for. I don't follow Node's development, so I'm just confused why the upstream change. It seems like a lot of tedious boilerplate just to run the utility scripts, and on top of that, if it's considered deprecated, what is the intended long-term solution?

My understanding here is that node20 (or really node 18.19.x) introduced a breaking change for loaders: https://nodejs.org/en/blog/announcements/v20-release-announce#custom-esm-loader-hooks-nearing-stable

This broke ts-node, see issue 1997 in https://github.com/TypeStrong/ts-node/issues (not linking directly to avoid more noise on that issue).

So, I think node --loader is deprecated. node --import is the long-term solution (as indicated by the error message I printed above). It's also possible that ts-node gets fixed and we can just run ts-node again in the future.

Edit: other people suggest switching to tsx but tsx uses esbuild, which is probably way faster but also doesn't support quite a few options that our tsconfig.json is using.

[quisquous]

The --loader parameter is deprecated and prints out an error. The way to get around this is to add a file (e.g. ./loader.js) with these contents:

import { register } from 'node:module';
import url from 'node:url';

const __filename = url.fileURLToPath(import.meta.url);
register('ts-node/esm', url.pathToFileURL(__filename));

and then instead of saying node --loader=ts-node/esm util/sync_files.ts you write node --import ./loader.js util/sync_files.ts

However, this doesn't work on node 18, and so we should only switch to it in the future once people stop using node 18.

See: a0679c9