Given requirements like:
```
black==23.1.0
black[colorama]
```
The resolver will (on `main`) add a dependency on Black, and then try to
use the most recent version of Black to satisfy `black[colorama]`. For
sake of example, assume `black==24.0.0` is the most recent version. Once
the selects this most recent version, it'll fetch the metadata, then
return the dependencies for `black==24.0.0` with the `colorama` extra
enabled. Finally, it will tack on `black==24.0.0` (a dependency on the
base package). The resolver will then detect a conflict between
`black==23.1.0` and `black==24.0.0`, and throw out
`black[colorama]==24.0.0`, trying to next most-recent version.
This is both wasteful and can cause problems, since we're fetching
metadata for versions that will _never_ satisfy the resolver. In the
`apache-airflow[all]` case, I also ran into an issue whereby we were
attempting to build very old versions of `apache-airflow` due to
`apache-airflow[pandas]`, which in turn led to resolution failures.
The solution proposed here is that we create a new proxy package with
exactly two dependencies: one on `black` and one of `black[colorama]`.
Both of these packages must be at the same version as the proxy package,
so the resolver knows much _earlier_ that (in the above example) the
extra variant _must_ match `23.1.0`.
Address a few pedantic lints
lints are separated into separate commits so they can be reviewed
individually.
I've not added enforcement for any of these lints, but that could be
added if desirable.
## Summary
This revives a PR from long ago
(https://github.com/astral-sh/uv/pull/383 and
https://github.com/zanieb/pubgrub/pull/24) that modifies how we deal
with dependencies that are declared multiple times within a single
package.
To quote from the originating PR:
> Uses an experimental pubgrub branch (#370) that allows us to handle
multiple version ranges for a single dependency to the solver which
results in better error messages because the derivation tree contains
all of the relevant versions. Previously, the version ranges were merged
(by us) in the resolver before handing them to pubgrub since only one
range could be provided per package. Since we don't merge the versions
anymore, we no longer give the solver an empty range for conflicting
requirements; instead the solver comes to that conclusion from the
provided versions. You can see the improved error message for direct
dependencies in [this
snapshot](https://github.com/astral-sh/puffin/pull/383/files#diff-a0437f2c20cde5e2f15199a3bf81a102b92580063268417847ec9c793a115bd0).
The main issue with that PR was around its handling of URL dependencies,
so this PR _also_ refactors how we handle those. Previously, we stored
URL dependencies on `PubGrubPackage`, but they were omitted from the
hash and equality implementations of `PubGrubPackage`. This led to some
really careful codepaths wherein we had to ensure that we always visited
URLs before non-URL packages, so that the URL-inclusive versions were
included in any hashmaps, etc. I considered preserving this approach,
but it would require us to rely on lots of internal details of PubGrub
(since we'd now be relying on PubGrub to merge those packages in the
"right" order).
So, instead, we now _always_ set the URL on a given package, whenever
that package was _given_ a URL upfront. I think this is easier to reason
about: if the user provided a URL for `flask`, then we should just
always add the URL for `flask`. If we see some other URL for `flask`, we
error, like before. If we see some unknown URL for `flask`, we error,
like before.
Closes https://github.com/astral-sh/uv/issues/1522.
Closes https://github.com/astral-sh/uv/issues/1821.
Closes https://github.com/astral-sh/uv/issues/1615.
First, replace all usages in files in-place. I used my editor for this.
If someone wants to add a one-liner that'd be fun.
Then, update directory and file names:
```
# Run twice for nested directories
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
# Update files
find . -type f -print0 | xargs -0 rename s/puffin/uv/g
```
Then add all the files again
```
# Add all the files again
git add crates
git add python/uv
# This one needs a force-add
git add -f crates/uv-trampoline
```