[pyupgrade] Fix false positive for TypeVar with default on Python<3.13 (UP046,UP047)
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….13 (`UP046`,`UP047`) Type default for Type parameter was added in Python 3.13 (PEP 696). `typing_extensions.TypeVar` backports the default argument to earlier versions. `UP046` & `UP047` were getting triggered when typing_extensions.TypeVar with `default` argument was used on python version < 3.13 It shouldn't be triggered for python version < 3.13 This commit fixes the bug by adding a python version check before triggering them. Fixes astral-sh#20929. Signed-off-by: Prakhar Pratyush <prakhar1144@gmail.com>
ntBre
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ntBre
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Oct 23, 2025
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Thank you! The code change and new comments look great, but would you mind converting your manual tests into regression tests in the repo?
If you already have separate Python files, they would fit nicely as new test cases alongside files like UP046_1.py and test_case entries here:
ruff/crates/ruff_linter/src/rules/pyupgrade/mod.rs
Lines 114 to 126 in 83a3bc4
Although you may need a separate test function so that you can set the version like we do here:
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Thanks for the review! As an update - I got busy with festivals around; I plan to complete this in the next 2-3 days. |
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Summary
Type default for Type parameter was added in Python 3.13 (PEP 696).
typing_extensions.TypeVarbackports the default argument to earlier versions.UP046&UP047were getting triggered whentyping_extensions.TypeVarwithdefaultargument was used on python version < 3.13It shouldn't be triggered for python version < 3.13
This commit fixes the bug by adding a python version check before triggering them.
Fixes #20929.
Test Plan
Manual testing 1
As the issue author pointed out in #20929 (comment), ran the following on
mainbranch:Output
Compiling ruff_linter v0.14.1 (/Users/prakhar/ruff/crates/ruff_linter) Compiling ruff v0.14.1 (/Users/prakhar/ruff/crates/ruff) Compiling ruff_graph v0.1.0 (/Users/prakhar/ruff/crates/ruff_graph) Compiling ruff_workspace v0.0.0 (/Users/prakhar/ruff/crates/ruff_workspace) Compiling ruff_server v0.2.2 (/Users/prakhar/ruff/crates/ruff_server) Finished `dev` profile [unoptimized + debuginfo] target(s) in 6.72s Running `target/debug/ruff check ../efax/ --target-version py312 --no-cache` UP046 Generic class `ExpectationParametrization` uses `Generic` subclass instead of type parameters --> /Users/prakhar/efax/efax/_src/expectation_parametrization.py:17:48 | 17 | class ExpectationParametrization(Distribution, Generic[NP]): | ^^^^^^^^^^^ 18 | """The expectation parametrization of an exponential family distribution. | help: Use type parameters UP046 Generic class `ExpToNat` uses `Generic` subclass instead of type parameters --> /Users/prakhar/efax/efax/_src/mixins/exp_to_nat/exp_to_nat.py:27:68 | 26 | @dataclass 27 | class ExpToNat(ExpectationParametrization[NP], SimpleDistribution, Generic[NP]): | ^^^^^^^^^^^ 28 | """This mixin implements the conversion from expectation to natural parameters. | help: Use type parameters UP046 Generic class `HasEntropyEP` uses `Generic` subclass instead of type parameters --> /Users/prakhar/efax/efax/_src/mixins/has_entropy.py:25:20 | 23 | HasEntropy, 24 | JaxAbstractClass, 25 | Generic[NP]): | ^^^^^^^^^^^ 26 | @abstract_jit 27 | @abstractmethod | help: Use type parameters UP046 Generic class `HasEntropyNP` uses `Generic` subclass instead of type parameters --> /Users/prakhar/efax/efax/_src/mixins/has_entropy.py:64:20 | 62 | class HasEntropyNP(NaturalParametrization[EP], 63 | HasEntropy, 64 | Generic[EP]): | ^^^^^^^^^^^ 65 | @jit 66 | @final | help: Use type parameters UP046 Generic class `NaturalParametrization` uses `Generic` subclass instead of type parameters --> /Users/prakhar/efax/efax/_src/natural_parametrization.py:43:30 | 41 | class NaturalParametrization(Distribution, 42 | JaxAbstractClass, 43 | Generic[EP, Domain]): | ^^^^^^^^^^^^^^^^^^^ 44 | """The natural parametrization of an exponential family distribution. | help: Use type parameters UP046 Generic class `Structure` uses `Generic` subclass instead of type parameters --> /Users/prakhar/efax/efax/_src/structure/structure.py:31:17 | 30 | @dataclass 31 | class Structure(Generic[P]): | ^^^^^^^^^^ 32 | """This class generalizes the notion of type for Distribution objects. | help: Use type parameters UP046 Generic class `DistributionInfo` uses `Generic` subclass instead of type parameters --> /Users/prakhar/efax/tests/distribution_info.py:20:24 | 20 | class DistributionInfo(Generic[NP, EP, Domain]): | ^^^^^^^^^^^^^^^^^^^^^^^ 21 | def __init__(self, dimensions: int = 1, safety: float = 0.0) -> None: 22 | super().__init__() | help: Use type parameters Found 7 errors. No fixes available (7 hidden fixes can be enabled with the `--unsafe-fixes` option).Running it after the changes:
ruff % cargo run -p ruff -- check ../efax/ --target-version py312 --no-cache Compiling ruff_linter v0.14.1 (/Users/prakhar/ruff/crates/ruff_linter) Compiling ruff v0.14.1 (/Users/prakhar/ruff/crates/ruff) Compiling ruff_graph v0.1.0 (/Users/prakhar/ruff/crates/ruff_graph) Compiling ruff_workspace v0.0.0 (/Users/prakhar/ruff/crates/ruff_workspace) Compiling ruff_server v0.2.2 (/Users/prakhar/ruff/crates/ruff_server) Finished `dev` profile [unoptimized + debuginfo] target(s) in 7.86s Running `target/debug/ruff check ../efax/ --target-version py312 --no-cache` All checks passed!Manual testing 2
Ran the check on the following script (mainly to verify
UP047):On
mainbranch:Output
Compiling ruff_linter v0.14.1 (/Users/prakhar/ruff/crates/ruff_linter) Compiling ruff v0.14.1 (/Users/prakhar/ruff/crates/ruff) Compiling ruff_graph v0.1.0 (/Users/prakhar/ruff/crates/ruff_graph) Compiling ruff_workspace v0.0.0 (/Users/prakhar/ruff/crates/ruff_workspace) Compiling ruff_server v0.2.2 (/Users/prakhar/ruff/crates/ruff_server) Finished `dev` profile [unoptimized + debuginfo] target(s) in 7.43s Running `target/debug/ruff check /Users/prakhar/up046.py --target-version py312 --preview --no-cache` UP047 Generic function `generic_function` should use type parameters --> /Users/prakhar/up046.py:10:5 | 10 | def generic_function(var: T) -> T: | ^^^^^^^^^^^^^^^^^^^^^^^^ 11 | return var | help: Use type parameters UP046 Generic class `GenericClass` uses `Generic` subclass instead of type parameters --> /Users/prakhar/up046.py:17:20 | 17 | class GenericClass(Generic[Q]): | ^^^^^^^^^^ 18 | var: Q | help: Use type parameters Found 2 errors. No fixes available (2 hidden fixes can be enabled with the `--unsafe-fixes` option).After the fix (this branch):