## Summary
This PR makes the behavior in https://github.com/astral-sh/uv/pull/9827
the default: we try to select the latest supported package version for
each supported Python version, but we still optimize for choosing fewer
versions when stratifying by platform.
However, you can opt out with `--fork-strategy fewest`.
Closes https://github.com/astral-sh/uv/issues/7190.
## Summary
These were moved as part of a broader refactor to create a single
integration test module. That "single integration test module" did
indeed have a big impact on compile times, which is great! But we aren't
seeing any benefit from moving these tests into their own files (despite
the claim in [this blog
post](https://matklad.github.io/2021/02/27/delete-cargo-integration-tests.html),
I see the same compilation pattern regardless of where the tests are
located). Plus, we don't have many of these, and same-file tests is such
a strong Rust convention.
As per
https://matklad.github.io/2021/02/27/delete-cargo-integration-tests.html
Before that, there were 91 separate integration tests binary.
(As discussed on Discord — I've done the `uv` crate, there's still a few
more commits coming before this is mergeable, and I want to see how it
performs in CI and locally).
## Summary
This is similar to https://github.com/astral-sh/uv/pull/6171 but more
expansive... _Anywhere_ that we test requirements for platform
compatibility, we _need_ to respect the resolver-friendly markers. In
fixing the motivating issue (#6621), I also realized that we had a bunch
of bugs here around `pip install` with `--python-platform` and
`--python-version`, because we always performed our `satisfy` and `Plan`
operations on the interpreter's markers, not the adjusted markers!
Closes https://github.com/astral-sh/uv/issues/6621.
Whew this is a lot.
The user-facing changes are:
- `uv toolchain` to `uv python` e.g. `uv python find`, `uv python
install`, ...
- `UV_TOOLCHAIN_DIR` to` UV_PYTHON_INSTALL_DIR`
- `<UV_STATE_DIR>/toolchains` to `<UV_STATE_DIR>/python` (with
[automatic
migration](https://github.com/astral-sh/uv/pull/4735/files#r1663029330))
- User-facing messages no longer refer to toolchains, instead using
"Python", "Python versions" or "Python installations"
The internal changes are:
- `uv-toolchain` crate to `uv-python`
- `Toolchain` no longer referenced in type names
- Dropped unused `SystemPython` type (previously replaced)
- Clarified the type names for "managed Python installations"
- (more little things)