private class field declaration generates #private in dts

[dnalborczyk]

TypeScript Version: 3.8.3 and v3.9.0 nightly

repro:

// ts
class FooBar {
    #foo = 'foo'

    bar() {
        return this.#foo
    }
}

Expected behavior:

// dts
declare class FooBar {
    bar(): string;
}

Actual behavior:

// dts
declare class FooBar {
    #private;
    bar(): string;
}

playground:
https://www.typescriptlang.org/play?ts=3.9.0-dev.20200418#code/MYGwhgzhAEBiD28BCYBO0DeAoavoGIAzRaAXmgHJj4Ksc8AjNACgEpN689UBTAFwCuqAHbQ+ACwCWEAHRFEnaAF8sSoA

Related Issues:
#36963
#36640
#36630

[RyanCavanaugh]

This is the intended behavior so that classes with #p private fields retain their nominal typing behavior when emitted to a .d.ts file

[pikadun]

@RyanCavanaugh

I used a npm package with d.ts containing #private, the compiler issues some errors, such as : '#private' is declared here., Property '#private' is missing in type xxx.

The #private in lib/api/Element.d.ts