## Summary
I tried running `py-fuzzer` using executables in the current working
directory, but that failed with:
```
▶ uvx --from ./python/py-fuzzer --reinstall fuzz --test-executable ./ty_feature --bin=ty --baseline-executable ./ty_main --only-new-bugs 0-500
Usage: fuzz [-h] [--only-new-bugs] [--quiet] [--test-executable TEST_EXECUTABLE] [--baseline-executable BASELINE_EXECUTABLE] --bin {ruff,ty} seeds [seeds ...]
fuzz: error: Bad argument passed to `--baseline-executable`: no such file or executable PosixPath('ty_main')
"Bad argument passed to `--baseline-executable`: no such file or executable PosixPath('ty_main')"
```
Using `.absolute()` on the `Path` fixes this.
## Test Plan
Successful `py-fuzzer` run with the invocation above.
## Summary
Add cycle handling for `try_metaclass` and `pep695_generic_context`
queries, as well as adjusting the cycle handling for `try_mro` to ensure
that it short-circuits on cycles and won't grow MROs indefinitely.
This reduces the number of failing fuzzer seeds from 68 to 17. The
latter count includes fuzzer seeds 120, 160, and 335, all of which
previously panicked but now either hang or are very slow; I've
temporarily skipped those seeds in the fuzzer until I can dig into that
slowness further.
This also allows us to move some more ecosystem projects from `bad.txt`
to `good.txt`, which I've done in
https://github.com/astral-sh/ruff/pull/17903
## Test Plan
Added mdtests.
Summary
--
Updates `fuzz.py` to run with `--preview`, which should allow it to
catch semantic syntax errors.
Test Plan
--
@AlexWaygood and I temporarily made any named expression a semantic
syntax error and checked that this led to fuzzing errors. We also tested
that reverting the `--preview` addition did not show any errors.
We also ran the fuzzer on 500 seeds on `main` but didn't find any
issues, (un)fortunately.
The red-knot CLI changed since the fuzzer script was added; update it to
work with current red-knot CLI.
Also add some notes on how to ensure local changes to the fuzzer script
are picked up.
## Summary
This PR builds on the changes in #16220 to pass a target Python version
to the parser. It also adds the `Parser::unsupported_syntax_errors` field, which
collects version-related syntax errors while parsing. These syntax
errors are then turned into `Message`s in ruff (in preview mode).
This PR only detects one syntax error (`match` statement before Python
3.10), but it has been pretty quick to extend to several other simple
errors (see #16308 for example).
## Test Plan
The current tests are CLI tests in the linter crate, but these could be
supplemented with inline parser tests after #16357.
I also tested the display of these syntax errors in VS Code:
---------
Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
## Summary
This PR gets rid of the `requirements.in` and `requirements.txt` files
in the `scripts/fuzz-parser` directory, and replaces them with
`pyproject.toml` and `uv.lock` files. The script is renamed from
`fuzz-parser` to `py-fuzzer` (since it can now also be used to fuzz
red-knot as well as the parser, following
https://github.com/astral-sh/ruff/pull/14566), and moved from the
`scripts/` directory to the `python/` directory, since it's now a
(uv)-pip-installable project in its own right.
I've been resisting this for a while, because conceptually this script
just doesn't feel "complicated" enough to me for it to be a full-blown
package. However, I think it's time to do this. Making it a proper
package has several advantages:
- It means we can run it from the project root using `uv run` without
having to activate a virtual environment and ensure that all required
dependencies are installed into that environment
- Using a `pyproject.toml` file means that we can express that the
project requires Python 3.12+ to run properly; this wasn't possible
before
- I've been running mypy on the project locally when I've been working
on it or reviewing other people's PRs; now I can put the mypy config for
the project in the `pyproject.toml` file
## Test Plan
I manually tested that all the commands detailed in
`python/py-fuzzer/README.md` work for me locally.
---------
Co-authored-by: David Peter <sharkdp@users.noreply.github.com>
