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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Closes https://github.com/astral-sh/ty/issues/989
There are various situations where users expect the Python packages
installed in the same environment as ty itself to be considered during
type checking. A minimal example would look like:
```
uv venv my-env
uv pip install my-env ty httpx
echo "import httpx" > foo.py
./my-env/bin/ty check foo.py
```
or
```
uv tool install ty --with httpx
echo "import httpx" > foo.py
ty check foo.py
```
While these are a bit contrived, there are real-world situations where a
user would expect a similar behavior to work. Notably, all of the other
type checkers consider their own environment when determining search
paths (though I'll admit that I have not verified when they choose not
to do this).
One common situation where users are encountering this today is with
`uvx --with-requirements script.py ty check script.py` — which is
currently our "best" recommendation for type checking a PEP 723 script,
but it doesn't work.
Of the options discussed in
https://github.com/astral-sh/ty/issues/989#issuecomment-3307417985, I've
chosen (2) as our criteria for including ty's environment in the search
paths.
- If no virtual environment is discovered, we will always include ty's
environment.
- If a `.venv` is discovered in the working directory, we will _prepend_
ty's environment to the search paths. The dependencies in ty's
environment (e.g., from `uvx --with`) will take precedence.
- If a virtual environment is active, e.g., `VIRTUAL_ENV` (i.e.,
including conda prefixes) is set, we will not include ty's environment.
The reason we need to special case the `.venv` case is that we both
1. Recommend `uvx ty` today as a way to check your project
2. Want to enable `uvx --with <...> ty`
And I don't want (2) to break when you _happen_ to be in a project
(i.e., if we only included ty's environment when _no_ environment is
found) and don't want to remove support for (1).
I think long-term, I want to make `uvx <cmd>` layer the environment on
_top_ of the project environment (in uv), which would obviate the need
for this change when you're using uv. However, that change is breaking
and I think users will expect this behavior in contexts where they're
not using uv, so I think we should handle it in ty regardless.
I've opted not to include the environment if it's non-virtual (i.e., a
system environment) for now. It seems better to start by being more
restrictive. I left a comment in the code.
## Test Plan
I did some manual testing with the initial commit, then subsequently
added some unit tests.
```
❯ echo "import httpx" > example.py
❯ uvx --with httpx ty check example.py
Installed 8 packages in 19ms
error[unresolved-import]: Cannot resolve imported module `httpx`
--> foo/example.py:1:8
|
1 | import httpx
| ^^^^^
|
info: Searched in the following paths during module resolution:
info: 1. /Users/zb/workspace/ty/python (first-party code)
info: 2. /Users/zb/workspace/ty (first-party code)
info: 3. vendored://stdlib (stdlib typeshed stubs vendored by ty)
info: make sure your Python environment is properly configured: https://docs.astral.sh/ty/modules/#python-environment
info: rule `unresolved-import` is enabled by default
Found 1 diagnostic
❯ uvx --from . --with httpx ty check example.py
All checks passed!
```
```
❯ uv init --script foo.py
Initialized script at `foo.py`
❯ uv add --script foo.py httpx
warning: The Python request from `.python-version` resolved to Python 3.13.8, which is incompatible with the script's Python requirement: `>=3.14`
Updated `foo.py`
❯ echo "import httpx" >> foo.py
❯ uvx --with-requirements foo.py ty check foo.py
error[unresolved-import]: Cannot resolve imported module `httpx`
--> foo.py:15:8
|
13 | if __name__ == "__main__":
14 | main()
15 | import httpx
| ^^^^^
|
info: Searched in the following paths during module resolution:
info: 1. /Users/zb/workspace/ty/python (first-party code)
info: 2. /Users/zb/workspace/ty (first-party code)
info: 3. vendored://stdlib (stdlib typeshed stubs vendored by ty)
info: make sure your Python environment is properly configured: https://docs.astral.sh/ty/modules/#python-environment
info: rule `unresolved-import` is enabled by default
Found 1 diagnostic
❯ uvx --from . --with-requirements foo.py ty check foo.py
All checks passed!
```
Notice we do not include ty's environment if `VIRTUAL_ENV` is set
```
❯ VIRTUAL_ENV=.venv uvx --with httpx ty check foo/example.py
error[unresolved-import]: Cannot resolve imported module `httpx`
--> foo/example.py:1:8
|
1 | import httpx
| ^^^^^
|
info: Searched in the following paths during module resolution:
info: 1. /Users/zb/workspace/ty/python (first-party code)
info: 2. /Users/zb/workspace/ty (first-party code)
info: 3. vendored://stdlib (stdlib typeshed stubs vendored by ty)
info: 4. /Users/zb/workspace/ty/.venv/lib/python3.13/site-packages (site-packages)
info: make sure your Python environment is properly configured: https://docs.astral.sh/ty/modules/#python-environment
info: rule `unresolved-import` is enabled by default
Found 1 diagnostic
```
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## Summary
#19990 didn't completely fix the base vs. child conda environment
distinction, since it detected slightly different behavior than what I
usually see in conda. E.g., I see something like the following:
```
(didn't yet activate conda, but base is active)
➜ printenv | grep CONDA
CONDA_PYTHON_EXE=/opt/anaconda3/bin/python
CONDA_PREFIX=/opt/anaconda3
CONDA_DEFAULT_ENV=base
CONDA_EXE=/opt/anaconda3/bin/conda
CONDA_SHLVL=1
CONDA_PROMPT_MODIFIER=(base)
(activating conda)
➜ conda activate test
(test is an active conda environment)
❯ printenv | grep CONDA
CONDA_PREFIX=/opt/anaconda3/envs/test
CONDA_PYTHON_EXE=/opt/anaconda3/bin/python
CONDA_SHLVL=2
CONDA_PREFIX_1=/opt/anaconda3
CONDA_DEFAULT_ENV=test
CONDA_PROMPT_MODIFIER=(test)
CONDA_EXE=/opt/anaconda3/bin/conda
```
But the current behavior looks for `CONDA_DEFAULT_ENV =
basename(CONDA_PREFIX)` for the base environment instead of the child
environment, where we actually see this equality.
This pull request fixes that and updates the tests correspondingly.
## Test Plan
I updated the existing tests with the new behavior. Let me know if you
want more tests. Note: It shouldn't be necessary to test for the case
where we have `conda/envs/base`, since one should not be able to create
such an environment (one with the name of `CONDA_DEFAULT_ENV`).
---------
Co-authored-by: Aria Desires <aria.desires@gmail.com>
## Summary
We use the `System` abstraction in ty to abstract away the host/system
on which ty runs.
This has a few benefits:
* Tests can run in full isolation using a memory system (that uses an
in-memory file system)
* The LSP has a custom implementation where `read_to_string` returns the
content as seen by the editor (e.g. unsaved changes) instead of always
returning the content as it is stored on disk
* We don't require any file system polyfills for wasm in the browser
However, it does require extra care that we don't accidentally use
`std::fs` or `std::env` (etc.) methods in ty's code base (which is very
easy).
This PR sets up Clippy and disallows the most common methods, instead
pointing users towards the corresponding `System` methods.
The setup is a bit awkward because clippy doesn't support inheriting
configurations. That means, a crate can only override the entire
workspace configuration or not at all.
The approach taken in this PR is:
* Configure the disallowed methods at the workspace level
* Allow `disallowed_methods` at the workspace level
* Enable the lint at the crate level using the warn attribute (in code)
The obvious downside is that it won't work if we ever want to disallow
other methods, but we can figure that out once we reach that point.
What about false positives: Just add an `allow` and move on with your
life :) This isn't something that we have to enforce strictly; the goal
is to catch accidental misuse.
## Test Plan
Clippy found a place where we incorrectly used `std::fs::read_to_string`
This is a port of the logic in https://github.com/astral-sh/uv/pull/7691
The basic idea is we use CONDA_DEFAULT_ENV as a signal for whether
CONDA_PREFIX is just the ambient system conda install, or the user has
explicitly activated a custom one. If the former, then the conda is
treated like a system install (having lowest priority). If the latter,
the conda is treated like an activated venv (having priority over
everything but an Actual activated venv).
Fixes https://github.com/astral-sh/ty/issues/611
by using essentially the same logic for system site-packages, on the
assumption that system site-packages are always a subdir of the stdlib
we were looking for.
## Summary
Fixes https://github.com/astral-sh/ty/issues/640. If a user passes
`--python=<some-virtual-environment>/bin/python`, we must avoid
canonicalizing the path until we've traversed upwards to find the
`sys.prefix` directory (`<some-virtual-environment>`). On Unix systems,
`<sys.prefix>/bin/python` is often a symlink to a system interpreter; if
we resolve the symlink too easily then we'll add the system
interpreter's `site-packages` directory as a search path rather than the
virtual environment's directory.
## Test Plan
I added an integration test to
`crates/ty/tests/cli/python_environment.rs` which fails on `main`. I
also manually tested locally that running `cargo run -p ty check foo.py
--python=.venv/bin/python -vv` now prints this log to the terminal
```
2025-06-20 18:35:24.57702 DEBUG Resolved site-packages directories for this virtual environment are: SitePackagesPaths({"/Users/alexw/dev/ruff/.venv/lib/python3.13/site-packages"})
```
Whereas it previously resolved `site-packages` to my system
intallation's `site-packages` directory
## Summary
Fixes https://github.com/astral-sh/ty/issues/556.
On Windows, system installations have different layouts to virtual
environments. In Windows virtual environments, the Python executable is
found at `<sys.prefix>/Scripts/python.exe`. But in Windows system
installations, the Python executable is found at
`<sys.prefix>/python.exe`. That means that Windows users were able to
point to Python executables inside virtual environments with the
`--python` flag, but they weren't able to point to Python executables
inside system installations.
This PR fixes that issue. It also makes a couple of other changes:
- Nearly all `sys.prefix` resolution is moved inside `site_packages.rs`.
That was the original design of the `site-packages` resolution logic,
but features implemented since the initial implementation have added
some resolution and validation to `resolver.rs` inside the module
resolver. That means that we've ended up with a somewhat confusing code
structure and a situation where several checks are unnecessarily
duplicated between the two modules.
- I noticed that we had quite bad error messages if you e.g. pointed to
a path that didn't exist on disk with `--python` (we just gave a
somewhat impenetrable message saying that we "failed to canonicalize"
the path). I improved the error messages here and added CLI tests for
`--python` and the `environment.python` configuration setting.
## Test Plan
- Existing tests pass
- Added new CLI tests
- I manually checked that virtual-environment discovery still works if
no configuration is given
- Micha did some manual testing to check that pointing `--python` to a
system-installation executable now works on Windows
## Summary
- Convert tests demonstrating our resilience to malformed/absent
`version` fields in `pyvenf.cfg` files to mdtests. Also make them more
expansive.
- Convert the regression test I added in
https://github.com/astral-sh/ruff/pull/18157 to an mdtest
- Add comments next to unit tests that cannot be converted to mdtests
(but where it's not obvious why they can't) so I don't have to do this
exercise again 😄
- In `site_packages.rs`, factor out the logic for figuring out where we
expect the system-installation `site-packages` to be. Currently we have
the same logic twice.
## Test Plan
`cargo test -p ty_python_semantic`
Follow-up to https://github.com/astral-sh/ruff/pull/17991 ensuring we do
not allow detection of system environments when the origin is
`VIRTUAL_ENV` or a discovered `.venv` directory — i.e., those always
require a `pyvenv.cfg` file.
Adds test coverage for https://github.com/astral-sh/ruff/pull/17991,
which includes some minor refactoring of the virtual environment test
infrastructure.
I tried to minimize stylistic changes, but there are still a few because
I was a little confused by the setup. I could see this evolving more in
the future, as I don't think the existing model can capture all the test
coverage I'm looking for.
This adds basic support for non-virtual Python environments by accepting
a directory without a `pyvenv.cfg` which allows existing, subsequent
site-packages discovery logic to succeed. We can do better here in the
long-term, by adding more eager validation (for error messages) and
parsing the Python version from the discovered site-packages directory
(which isn't relevant yet, because we don't use the discovered Python
version from virtual environments as the default `--python-version` yet
either).
Related
- https://github.com/astral-sh/ty/issues/265
- https://github.com/astral-sh/ty/issues/193
You can review this commit by commit if it makes you happy.
I tested this manually; I think refactoring the test setup is going to
be a bit more invasive so I'll stack it on top (see
https://github.com/astral-sh/ruff/pull/17996).
```
❯ uv run ty check --python /Users/zb/.local/share/uv/python/cpython-3.10.17-macos-aarch64-none/ -vv example
2025-05-09 12:06:33.685911 DEBUG Version: 0.0.0-alpha.7 (f9c4c8999 2025-05-08)
2025-05-09 12:06:33.685987 DEBUG Architecture: aarch64, OS: macos, case-sensitive: case-insensitive
2025-05-09 12:06:33.686002 DEBUG Searching for a project in '/Users/zb/workspace/ty'
2025-05-09 12:06:33.686123 DEBUG Resolving requires-python constraint: `>=3.8`
2025-05-09 12:06:33.686129 DEBUG Resolved requires-python constraint to: 3.8
2025-05-09 12:06:33.686142 DEBUG Project without `tool.ty` section: '/Users/zb/workspace/ty'
2025-05-09 12:06:33.686147 DEBUG Searching for a user-level configuration at `/Users/zb/.config/ty/ty.toml`
2025-05-09 12:06:33.686156 INFO Defaulting to python-platform `darwin`
2025-05-09 12:06:33.68636 INFO Python version: Python 3.8, platform: darwin
2025-05-09 12:06:33.686375 DEBUG Adding first-party search path '/Users/zb/workspace/ty'
2025-05-09 12:06:33.68638 DEBUG Using vendored stdlib
2025-05-09 12:06:33.686634 DEBUG Discovering site-packages paths from sys-prefix `/Users/zb/.local/share/uv/python/cpython-3.10.17-macos-aarch64-none` (`--python` argument')
2025-05-09 12:06:33.686667 DEBUG Attempting to parse virtual environment metadata at '/Users/zb/.local/share/uv/python/cpython-3.10.17-macos-aarch64-none/pyvenv.cfg'
2025-05-09 12:06:33.686671 DEBUG Searching for site-packages directory in `sys.prefix` path `/Users/zb/.local/share/uv/python/cpython-3.10.17-macos-aarch64-none`
2025-05-09 12:06:33.686702 DEBUG Resolved site-packages directories for this environment are: ["/Users/zb/.local/share/uv/python/cpython-3.10.17-macos-aarch64-none/lib/python3.10/site-packages"]
2025-05-09 12:06:33.686706 DEBUG Adding site-packages search path '/Users/zb/.local/share/uv/python/cpython-3.10.17-macos-aarch64-none/lib/python3.10/site-packages'
...
❯ uv run ty check --python /tmp -vv example
2025-05-09 15:36:10.819416 DEBUG Version: 0.0.0-alpha.7 (f9c4c8999 2025-05-08)
2025-05-09 15:36:10.819708 DEBUG Architecture: aarch64, OS: macos, case-sensitive: case-insensitive
2025-05-09 15:36:10.820118 DEBUG Searching for a project in '/Users/zb/workspace/ty'
2025-05-09 15:36:10.821652 DEBUG Resolving requires-python constraint: `>=3.8`
2025-05-09 15:36:10.821667 DEBUG Resolved requires-python constraint to: 3.8
2025-05-09 15:36:10.8217 DEBUG Project without `tool.ty` section: '/Users/zb/workspace/ty'
2025-05-09 15:36:10.821888 DEBUG Searching for a user-level configuration at `/Users/zb/.config/ty/ty.toml`
2025-05-09 15:36:10.822072 INFO Defaulting to python-platform `darwin`
2025-05-09 15:36:10.822439 INFO Python version: Python 3.8, platform: darwin
2025-05-09 15:36:10.822773 DEBUG Adding first-party search path '/Users/zb/workspace/ty'
2025-05-09 15:36:10.822929 DEBUG Using vendored stdlib
2025-05-09 15:36:10.829872 DEBUG Discovering site-packages paths from sys-prefix `/tmp` (`--python` argument')
2025-05-09 15:36:10.829911 DEBUG Attempting to parse virtual environment metadata at '/private/tmp/pyvenv.cfg'
2025-05-09 15:36:10.829917 DEBUG Searching for site-packages directory in `sys.prefix` path `/private/tmp`
ty failed
Cause: Invalid search path settings
Cause: Failed to discover the site-packages directory: Failed to search the `lib` directory of the Python installation at `sys.prefix` path `/private/tmp` for `site-packages`
```
