Defer conditional types with parenthesized multi-element tuple types in extends clause

[Andarist]

fixes #56270

[ahejlsberg]

As per my comments here I don't think we want this to change.

[Andarist]

Reopening on @jakebailey’s request

[jakebailey]

@typescript-bot pack this

[typescript-bot]

Heya @jakebailey, I've started to run the tarball bundle task on this PR at ec113c0. You can monitor the build here.

[typescript-bot]

Hey @jakebailey, I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/158427/artifacts?artifactName=tgz&fileId=3F0CBC6645E4050DB9EB24473D159E55AE9EC546D964A9872D9BE8BC0677FB1802&fileName=/typescript-5.3.0-insiders.20231101.tgz"
    }
}

and then running npm install.

---

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@5.3.0-pr-56271-4".;

[craigphicks]

If we were resolving from the inside out, rather than the outside in, we would also cover cases like [...[<something>],...[<something>]] which may resolve to simple tuples.

[jakebailey]

I'm not sure if this is what you mean, but potentially a better fix would have been to strip parens around anything passed into isSimpleTupleType and any node it examines.

[jakebailey]

Well, that can't be the actual implementation, but almost. I'll send a PR for discussion as the parens inside are still significant (and my intention was to not have that be the case).

[jakebailey]

I am confusing myself; this doesn't matter; isSimpleTupleType looks at the elements and only cares about optional/rest/named members, which cannot be parenthesized. So maybe you meant something else?

Basically, the intent is just "parens don't affect semantics"; anything else is out of scope.

[craigphicks]

I think "out of scope" covers it. But what I meant was an inside-to-outside order processing of nodes to types. That would include stripping parens, but also more.