Generic type parameters considered private in protected methods when generating .d.ts

[jctitor]

The following code fails in TypeScript 1.4 with the below errors:

export class MyClass {
    protected myMethod<T>(val: T): T {
        return val;
    }
}

Parameter 'val' of public method from exported class has or is using private name 'T'.
Return type of public method from exported class has or is using private name 'T'.

[danquirk]

I'm not seeing this on the latest bits. Is there something more to the repro?

[jctitor]

I apologize, this only manifests if "Generate declaration files" is selected for the project.

[danquirk]

Ah, there we go :)

[jctitor]

This issue is a mismatch between the checker visibility rules and the emitter output rules.

The checker's determineIfDeclarationIsVisible function considers a Protected method to be not visible. However, the emitter's emitParameterDeclaration and emitSignatureDeclaration functions will emit parameter/return types for non-Private methods. Thus protected methods cause emitting of a non-visible type, resulting in a "of_public_method_from_exported_class_has_or_is_using_private_name" class of error.

I don't have sufficient knowledge of the codebase to submit a PR, but time-permitting it would be fantastic if a fix could make it into the 1.4 release. Our organization relies on .d.ts generation as a means of simulating .dlls, such that we can depend on a common set of "library" projects for our various application projects. This defect would in many instances prevent using protected in such libraries.

[danquirk]

This was broken by 1.4, it worked in 1.3.

[bluong]

We have an issue arising from the fact that this worked in 1.3 but not in 1.4. Is it possible for a fix for this to be made for the 1.4 release. Otherwise, we're gonna have a back-compat break.

[RyanCavanaugh]

Referenced PR got cherry-picked into 1.4

[derekcicerone-zz]

Awesome, thanks for the quick fix!