Allow specifying TReturn and TNext for AsyncIterableIterator and AsyncIterable

[Brian Terlson (bterlson)]

Partially fixes#33932 by giving a way to provide a better type than any for TReturn. Implementation is simply adding and plumbing the TReturn and TNext parameters for both AsyncIterableIterator and AsyncIterable, and updating baselines.

[Daniel Rosenwasser (DanielRosenwasser)]

TypeScript Bot (@typescript-bot) test this
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TypeScript Bot (@typescript-bot) run dt

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the extended test suite on this PR at 3b69bf2. You can monitor the build here. It should now contribute to this PR's status checks.

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the parallelized Definitely Typed test suite on this PR at 3b69bf2. You can monitor the build here. It should now contribute to this PR's status checks.

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the parallelized community code test suite on this PR at 3b69bf2. You can monitor the build here. It should now contribute to this PR's status checks.

[TypeScript Bot (typescript-bot)]

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

[Brian Terlson (bterlson)]

TypeScript Bot (@typescript-bot) test this
TypeScript Bot (@typescript-bot) user test this
TypeScript Bot (@typescript-bot) run dt

[TypeScript Bot (typescript-bot)]

Heya Brian Terlson (@bterlson), I've started to run the parallelized Definitely Typed test suite on this PR at aa0f332. You can monitor the build here. It should now contribute to this PR's status checks.

[TypeScript Bot (typescript-bot)]

Heya Brian Terlson (@bterlson), I've started to run the parallelized community code test suite on this PR at aa0f332. You can monitor the build here. It should now contribute to this PR's status checks.

[TypeScript Bot (typescript-bot)]

Heya Brian Terlson (@bterlson), I've started to run the extended test suite on this PR at aa0f332. You can monitor the build here. It should now contribute to this PR's status checks.

[ExE Boss (ExE-Boss)]

What about Iterable and IterableIterator?

Also, do note that this was originally rejected in #30790 (comment) by Ron Buckton (@rbuckton).

[Brian Terlson (bterlson)]

ExE Boss (@ExE-Boss) I would argue for similar treatment, but given Ron Buckton (@rbuckton)'s trepidation I think we should wait and see what he thinks. If adding Iterable and IterableIterator to this PR would help, I will do it!

[Ron Buckton (rbuckton)]

At one point in #30790 I was using unknown instead of any. The problem with undefined as a default is that not everyIterator can be assumed to return undefined, and making the type anything other than any or unknown caused a significant number of breaks in assignability where people were rolling their own custom iterators.

We also had issues with the fact that we were conflating T in Iterator and Iterable to include both the yielded and the returned type, and the fact that Iterator<T> was originally typed with return?(value?: any):

I am considering my concerns about adding TReturn and TNext to Iterable. My main concern is that it would dramatically increase .d.ts file output if suddenly every inferred Iterable<number> in the output became Iterable<number, void, undefined> because we fill in the default types at the time of compilation.

[Nathan Shively-Sanders (sandersn)]

Unfortunately, we never finished reviewing this PR. It is pretty old now, so I'm going to close it to reduce the number of open PRs.