Currently, the fields, types and defaults used to define a typing.NamedTuple need to be retrieved from three different attributes: `_fields`, `_field_types`, and `_field_defaults` (the first two are combined in `__annotations__`, but that still misses the defaults).

However, there is a place where all this information can be naturally combined: in the Signature of the constructor (as returned by `inspect.signature(cls)`).  Currently, the Parameter objects in the signature have the information about the parameter names and defaults, but their annotation is not set.

Thus, I would like to propose setting the annotation of the Parameters in the Signature object as well.

This looks like a reasonable idea, if it is possible to implement this without complications. Would you like to submit a PR at https://github.com/python/typing ?

(We have a separate upstream repo for typing while it is provisional.)

I'll just repost the issue there for now (https://github.com/python/typing/issues/454).  May work on a patch at some point (looks relatively simple) but no guarantees, so if someone else wants to take over feel free to do so.

IMHO this issue can be closed with this commit (https://github.com/python/typing/commit/435b29470c7d3e87055531f65681bee9746ab999)

Thanks! It looks like this was fixed in typing and then forward ported to CPython.