@typescript-bot test this

Heya @weswigham, I've started to run the extended test suite on this PR at 2c47d31. You can monitor the build here. It should now contribute to this PR's status checks.

@RyanCavanaugh I see you marked this for TS 3.2. Is that still the plan?

@typescript-bot pack this

Heya @orta, I've started to run the tarball bundle task on this PR at 05f63f6. You can monitor the build here.

Hey @orta, 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/98697/artifacts?artifactName=tgz&fileId=FCFFE06ACEDE5A9CF492C0B487ADB414731BE223F7CF66D693D5A513375E6B9102&fileName=/typescript-4.3.0-insiders.20210318.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@4.3.0-pr-26797-61".;

Hello, I found this PR and I am looking forward to its release.

A question about this PR.
I want to define an object type that can only accept a numeric string as a key.
In the following code, why does an error occur for the key "100"?

type NumStr = `${number}`
type Obj = { [key: `${NumStr}`]: string }
const obj: Obj = { 
    "0xff": "", // OK
    "100e10": "", // OK
    "100": "", // NG, but why?
}
// Type '{ "0xff": string; "100e10": string; "100": string; }' is not assignable to type 'Obj'.
// Object literal may only specify known properties, and '"100"' does not exist in type 'Obj'.

Playground Link

#41821

Could this support optional indexers? This seems to work with the in operator but not the : operator.

type OptionalKeyedType = {
  [k in typeof ENUM[keyof typeof ENUM]]?: unknown;
};
interface DirectOptionalKeyed {
  [k: typeof ENUM[keyof typeof ENUM]]?: unknown; // ';' expected.(1005)
}

Playground link

@weswigham What's the status of this? The PR is still open and has the "Backlog" milestone, yet on the roadmap it's marked as done and already part of typescript@next.

What's the status of this?

It's been superseded by #44512.