Fix name resolution in typedef and allow defaults for template tags

[rbuckton]

This adds support for Type Parameter defaults in JavaScript files using the JSDoc @template tag. The implementation borrows from the syntax used for parameter defaults in JSDoc (namely [foo=1]):

/**
 * @template {string} [T="hello"]
 * @typedef {T} Foo
 */

This also fixes a name resolution bug when checking the constraint of a @template tag.

Fixes #45480
Fixes #45481

[sandersn]

Looks good, one request in the parser and one in the tests.

[rbuckton]

I'm debating whether [T] should be allowed, and if so, if it should default to the constraint or unknown. Given the changes necessary to support that, I may look at that in a separate PR instead.

[rbuckton]

@sandersn can you take another look?

[rbuckton]

@typescript-bot test this
@typescript-bot user test this

[typescript-bot]

Heya @rbuckton, I've started to run the parallelized community code test suite on this PR at 9131c0c. You can monitor the build here.

[typescript-bot]

Heya @rbuckton, I've started to run the extended test suite on this PR at 9131c0c. You can monitor the build here.

[typescript-bot]

The user suite test run you requested has finished and failed. I've opened a PR with the baseline diff from master.

[rbuckton]

• User Tests: lots of diffs in baselines, but none seem related to this change.
  • NOTE: Prettier has same OOM as Adds 'Awaited' type alias and updates to Promise.all/race/allSettled/any #45350 (comment), so I think there's something unrelated to this PR or Adds 'Awaited' type alias and updates to Promise.all/race/allSettled/any #45350.
• RWC: no changes of note.

[andrewbranch]

@rbuckton FYI you can run @typescript-bot user test this inline to get a user test diff between this and current main, with results posted in the PR.

[typescript-bot]

Heya @andrewbranch, I've started to run the inline community code test suite on this PR at 9131c0c. You can monitor the build here.

Update: The results are in!

[typescript-bot]

@andrewbranch
Great news! no new errors were found between main..refs/pull/45483/merge

[rbuckton]

Wasn't aware of the inline, and I'm not sure why that's not the default behavior, tbh.

[rbuckton]

@DanielRosenwasser: Do we want to discuss the syntax for this in a design meeting, or is this ok to merge?

[rbuckton]

TODO:

• Verify JS declaration emit.

[DanielRosenwasser]

So the syntax

@template {string} [T="hello"]

means

T extends string = "hello"

I can't wait to never get this right. 😂

[thw0rted]

Hi @rbuckton , I noticed that none of the files changed in this PR seem to be documentation (HTML/MD). Is that hosted in a different repo? Is there a task / issue to track inclusion of this syntax in the handbook?

[orta]

Just noting that the new JSDoc reference on the site includes this