Emitting type parameters (regression)

[falsandtru]

TypeScript Version: master

Search Terms:

Code

export class MyMap<K, V> {
	constructor(
		private readonly Map_: typeof Map = Map
	) {
	}
	private readonly store = new this.Map_<K, V>();
}

Expected behavior:

export class MyMap {
    constructor(Map_ = Map) {
        this.Map_ = Map_;
        this.store = new this.Map_();
    }
}

Actual behavior:

export class MyMap {
    constructor(Map_ = Map) {
        this.Map_ = Map_;
        this.store = new this.Map_<K, V>();
    }
}

Playground Link:

Related Issues:

[jcalz]

Wow, yeah. That's not great.

[fatcerberus]

Ouch.

[ahejlsberg]

Whatever the regression is, it causes 28 projects in the RWC test suite to break.

@andrewbranch I'd suggest bisecting this and reverting whichever PR caused the break.

[andrewbranch]

My theory is it's #30467. I'm stepping through now to see if there's a quick fix, but I'll revert the offending PR if I can't figure it out in the next 30 minutes or so.

[ahejlsberg]

@andrewbranch Yup, RWC looks to run clean on the last commit prior to #30467.

@rbuckton Ping.

[rbuckton]

I'll take a look. It looks like we didn't have a test for this case (in our normal tests).

[andrewbranch]

@rbuckton I've got a fix incoming.

[falsandtru]

Can you also take a look at another regression #31277?

[falsandtru]

@ahejlsberg You don't still have a test for this case.