This is a drive-by improvement that I stumbled backwards into while
looking into
* https://github.com/astral-sh/ty/issues/296
I was writing some simple tests for "thing not in old version of stdlib"
diagnostics and checked what was added in 3.14, and saw
`compression.zstd` and to my surprise discovered that `import
compression.zstd` and `from compression import zstd` had completely
different quality diagnostics.
This is because `compression` and `compression.zstd` were *both*
introduced in 3.14, and so per VERSIONS policy only an entry for
`compression` was added, and so we don't actually have any definite info
on `compression.zstd` and give up on producing a diagnostic. However the
`from compression import zstd` form fails on looking up `compression`
and we *do* have an exact match for that, so it gets a better
diagnostic!
(aside: I have now learned about the VERSIONS format and I *really* wish
they would just enumerate all the submodules but, oh well!)
The fix is, when handling an import failure, if we fail to find an exact
match *we requery with the parent module*. In cases like
`compression.zstd` this lets us at least identify that, hey, not even
`compression` exists, and luckily that fixes the whole issue. In cases
where the parent module and submodule were introduced at different times
then we may discover that the parent module is in-range and that's fine,
we don't produce the richer stdlib diagnostic.
Aria Desires
Carl Meyer
Alex Waygood
Charlie Marsh
Micha Reiser