Tighten numpy.linalg.qr annotation

[NeilGirdhar]

No description provided.

[NeilGirdhar]

@jakevdp (Sorry if this is too many annotation PRs)

[dfm]

Looks ok to me, but it's not totally obvious to me that there's a huge benefit to including all the supported literals in the type as demonstrated by the fact that this is already inconsistent with the runtime values that are supported. What do you think?

[dfm]

It looks like "full" is also supported. I wonder if we should add that too, but this also means that we need to keep this annotation in sync with runtime values supported. Is it possible to annotate "any string except the literal "r""?

[jakevdp]

I've typically avoided Literal in type annotations outside specific overloads, because then if you do something like this:

mode: str = "reduced"
qr(..., mode=mode)

it will result in a type error, becuase str is not a valid type for mode. In my experience this kind of pattern is used often enough that changes like this lead to many downstream failures, and the effort required to land them outweighs the benefit.