Provide better completions when comparing literal

[rchl]

Is your feature request related to a problem? Please describe.

It would be nice if pyright would provide completions in a comparison expression if one side has literal value(s).

An example will best describe my feature request:

from typing import Literal, Union


def get_drink() -> Union[Literal['cola'], Literal['pepsi']]:
    return 'cola'


is_pepsi = get_drink() == 'pepsi'

Describe the solution you'd like

When on the last line, after the == operator, triggering completions could bring up completions for 'cola' and 'pepsi'.

This would just speed up writing and make it clear what the value can be compared to.

Additional context

I found microsoft/pyright#335 which is very similar and was implemented but it doesn't work in that context.

(Also the comparison operator could raise a notice if the compared operands don't have any type in common as then the comparison should never result in True but it seems like a completely separate feature request.)

[erictraut]

Since this enhancement request is a language service feature rather than a core type checking feature, I'm going to transfer it to the pylance repo. It will get the appropriate discussion and consideration there.

[judej]

Moving this issue to discussion as an enhancement request for comments and upvotes.