Language service: open Type.id

I am using language service to "traverse" the program, and I would like very much to "remember" which types and symbols I already saw, and to cache my computation results for them. Performance boost and avoiding infinite loops.

The compiler very helpfully supplies id for Type, Symbol and Node, and it seems to be "really, really" unique for symbols and nodes, and "relatively unique" (i.e. within a given typechecker) for types.

The problem is, however, that, unlike nodes and symbols, types hide their ids behind the "internal" qualifier and the lack of accessor function, making them not legally visible to me as a consumer of the language service. Of course, this being JavaScript, nothing prevents me from accessing them anyway, and that is what I currently do, but this is not ideal, because I am not protected from the code evolution in the future.

So it seems to me that nothing stands in the way of adding a getTypeId method to the typechecker, unless I'm missing something very important.

Beginne mit src/compiler/checker.ts und src/compiler/types.ts, insbesondere mit der Type-Definition und der bestehenden Identity-Behandlung des Typecheckers, die im Issue beschrieben wird. Verfolge, wie öffentliche Language-Service- und Type-Checker-APIs deklariert und getestet werden, ermittle dann, was für einen unterstützten Zugriff auf den Typbezeichner erforderlich ist, und überprüfe, ob der offengelegte Bezeichner innerhalb eines Typecheckers weiterhin nützlich ist.