Request: Omitting experimental flags from new config file

[jasnell]

Opening this issue on behalf of several individuals with whom I spoke about the new configuration file landed in #57016 ...

The specific request from three separate people in separate conversations is to specifically omit --experimental-* flags from the configuration file format, even if hose flags are otherwise allowed in NODE_OPTIONS.

/cc @marco-ippolito @ljharb @ShogunPanda @anonrig @joyeecheung @mhdawson @bnb (as the folks who authored/reviewed that PR)

[marco-ippolito]

I'm not against it but I would like the decision to be properly motivated.
Experimental options are already hardcoded in .env files and package.json

[jasnell]

Absolutely fair... I opened the issue so that we can discuss the motivation. I can see it both ways so not sure I'm best to articulate the motivation. I'm sending this issue link to multiple people with the hope they will weigh in.

[pmarchini]

A thought regarding a specific use case: the test runner has many experimental flags and is, in fact, largely experimental.
The configuration file potentially has a strong application in this specific area.

I wonder, for this reason, if it might make sense to consider handling exceptions when it comes to not allowing experimental flags to be managed via the file.

[joyeecheung]

I wonder if we can solve the problem by:

• Make sure experimental features that we don't want widespread usage always lead to a runtime warning
• Make sure this warning cannot be disabled via the config file (if the --no-warnings or other warning flags specifically come from the config file, they are not effective for experimental warnings...or deprecation warnings, for that matter).
• When we want experimental features to get wider usage, we either remove the warning, or allow it to be disabled by files