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• I havesearched for related issues and found none that match my proposal.
• I have searched thecurrent rule list and found no rules that match my proposal.
• I haveread the FAQ and my problem is not listed.

Relevant Package

parser

My proposal is suitable for this project

• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Description

I've heard of two requests aroundEXPERIMENTAL_useProjectService:

• Customize the default options in the case of atsconfig.json not existing:https://discord.com/channels/508357248330760243/640177429775777792/1163326359100199012
• Warn if it's being used:feat(typescript-estree): add allowDefaultProjectForFiles project service allowlist option #7752 (comment)

These are technically two requests, but I think it'd be good to discuss them together. Whatever API we end up going with may need to accommodate both.

Proposal: how about afallbackCompilerOptions?

typeFallbackCompilerOptions=/* Don't allow fallback/inferred projects at all */|"error"/* Allow fallback/inferred projects but log a warning */|"warn"/* Directly use these */ts.CompilerOptions;// (approximation of the shape we'd allow)interfaceProjectServiceParserOptions{EXPERIMENTAL_useProjectService:true;// If undefined, go with TypeScript's defaultsfallbackCompilerOptions?:FallbackCompilerOptions;}

Additional Info

Courtesy of@jakebailey inhttps://discord.com/channels/508357248330760243/1163326359100199012/1163526441103802398: project services have asetCompilerOptionsForInferredProjects we can use.

#7752 largely enables the case of an inferred project in the first place.

Edit: oh, and also mentioned here:#6575 (comment)