JSDoc supports null, undefined and never types

[sandersn]

This was missing from the literal types PR.

[sandersn]

@mhegazy this was easier than I thought it would be, but no less annoying since I had to duplicate JSDoc type nodes for all three types.

[sandersn]

Looks like I need to edit baselines in some unit tests in src/harness/unittests/jsDocParsing.ts

[sandersn]

OK, unit tests should be fixed now.

[DanielRosenwasser]

It'd be good to see a test where you still get a completion list for all the members on null | undefined | { foo: number }.

Also, more of a general question (and I don't actually think you should take out the functionality), but what purpose does the never type really have in Salsa?

[DanielRosenwasser]

Actually, perhaps you shouldn't see the member list until you've narrowed down.

The bug that probably isn't taken care of here is that you do show the member list for something that's nullable because in Salsa we always show members from every type in a union.

[sandersn]

1. why never et al?

Jsdoc isn't just for salsa. It's also for --allowJs. You can pre-convert files that aren't ready to be .ts yet so that you can get good information and errors in the files that you have been able to convert to .ts. For example, you could even write assertNever in .js and use it from .ts.

2. Completion members

I'll add the test. I don't think --allowJs respects --strictNullChecks, but maybe that's an effect of the show-all-union-members behaviour you're talking about.

[sandersn]

OK, I added the fourslash test.

[mhegazy]

👍