this type in conditional type false clause is incorrectly typed

TypeScript Version: 3.7.3

Search Terms:
generic type this widening incorrect

Code

type Option1 = { run(this: { b: 1 }): void }

function f1(options: Option1) { return options }

// `this` is correctly typed as `{ b: 1 }`
f1({ run() { this.b } })

type Option2<Config> = Config extends Record<string, any> ? {
  config: Config,
  run(this: Config): void
} : {
  run(arg: { b: 1 }): void
}

function f2<Config>(options: Option2<Config>) { return options }

// `this` is correctly typed as `{ a: number }`
f2({ config: { a: 1 }, run() { this.a } })
// `arg` is correctly typed as `{ b: 1 }`
f2({ run(arg) { arg.b } })

type Option3<Config> = Config extends Record<string, any> ? {
  config: Config,
  run(this: Config): void
} : {
  run(this: { b: 1 }): void
}

function f3<Config>(options: Option3<Config>) { return options }

// `this` is correctly typed as `{ a: number }`
f3({ config: { a: 1 }, run() { this.a } })
// `this` is widen to what `Config` extends to. In this case `Record<string, any>`
f3({ run() { this.b } })

Expected behavior:
this in f3({ run() { this.b } }) should be typed as in this in f1() and arg in f2()

Actual behavior:
this in f3({ run() { this.b } }) is typed as the base type of Config (Record<string,any> in the example above)

Playground Link:
Playground Link

Related Issues:
Some maybe related issues:
https://github.com/microsoft/TypeScript/issues/32990
https://github.com/microsoft/TypeScript/issues/30152
https://github.com/microsoft/TypeScript/issues/13995

I also recall there were some discussion about type and Record<>, but that is in the gitter channel and I can't find relevant issue or doc about it.

I think this is different than the related issues above because this does not involve union type.

This is about the false condition of the conditional type Config extends Record<string, any> ? ... : ... do not use the generic type Config and should not be affected by it.

リンクされている TypeScript Playground の例を再現し、f1、f2、f3 における this のコンテキスト型を比較します。false 節に対する conditional type のコンテキスト型付けを調査します。f3 のコールバックの this が拡張されたベース型ではなく { b: 1 } として型付けされ、他の例にリグレッションが発生しないことが完了の条件です。