Codify linkcheck status codes into a Literal

[AA-Turner]

Alternative to #13039. This changes nothing in the runtime other than narrowing the current str to a Literal. Note that Literal[''] is needed in a couple of places because of this.

cc @jayaddison

A

[jayaddison]

Alternative to #13039. This changes nothing in the runtime other than narrowing the current str to a Literal. Note that Literal[''] is needed in a couple of places because of this.

Yep, sounds good. What do you think about introducing an unknown status to initialize to instead of '' in a subsequent change? In practice I don't think it should ever not be assigned to a valid value, but empty-string does look a bit quirky (again, agreed with the refactor-only idea though).

[AA-Turner]

Thanks!

What do you think about introducing an unknown status to initialize to instead of '' in a subsequent change?

In practice, '' is a logic error. It is only reached if retries is 0, which is an illegal value (though seemingly allowed at present). The logic is to return the first non-failing result or the final result if all fail. (Edit: but adding 'unknown' sounds good!)

A

[jayaddison]

I like it 👍

As an aside: I think I may have misunderstood the incompatibility of Literal with StrEnum - perhaps both can be combined effectively here after all.