mirror of
https://github.com/astral-sh/ruff.git
synced 2025-09-29 05:15:12 +00:00
9c47b6dbb0
## Summary This PR extends version-related syntax error detection to red-knot. The main changes here are: 1. Passing `ParseOptions` specifying a `PythonVersion` to parser calls 2. Adding a `python_version` method to the `Db` trait to make this possible 3. Converting `UnsupportedSyntaxError`s to `Diagnostic`s 4. Updating existing mdtests to avoid unrelated syntax errors My initial draft of (1) and (2) in #16090 instead tried passing a `PythonVersion` down to every parser call, but @MichaReiser suggested the `Db` approach instead [here](https://github.com/astral-sh/ruff/pull/16090#discussion_r1969198407), and I think it turned out much nicer. All of the new `python_version` methods look like this: ```rust fn python_version(&self) -> ruff_python_ast::PythonVersion { Program::get(self).python_version(self) } ``` with the exception of the `TestDb` in `ruff_db`, which hard-codes `PythonVersion::latest()`. ## Test Plan Existing mdtests, plus a new mdtest to see at least one of the new diagnostics.
5.4 KiB
5.4 KiB
Pattern matching
[environment]
python-version = "3.10"
With wildcard
def _(target: int):
match target:
case 1:
y = 2
case _:
y = 3
reveal_type(y) # revealed: Literal[2, 3]
Without wildcard
def _(target: int):
match target:
case 1:
y = 2
case 2:
y = 3
# revealed: Literal[2, 3]
# error: [possibly-unresolved-reference]
reveal_type(y)
Basic match
def _(target: int):
y = 1
y = 2
match target:
case 1:
y = 3
case 2:
y = 4
reveal_type(y) # revealed: Literal[2, 3, 4]
Value match
A value pattern matches based on equality: the first case branch here will be taken if subject
is equal to 2, even if subject is not an instance of int. We can't know whether C here has a
custom __eq__ implementation that might cause it to compare equal to 2, so we have to consider
the possibility that the case branch might be taken even though the type C is disjoint from the
type Literal[2].
This leads us to infer Literal[1, 3] as the type of y after the match statement, rather than
Literal[1]:
from typing import final
@final
class C:
pass
def _(subject: C):
y = 1
match subject:
case 2:
y = 3
reveal_type(y) # revealed: Literal[1, 3]
Class match
A case branch with a class pattern is taken if the subject is an instance of the given class, and
all subpatterns in the class pattern match.
from typing import final
class Foo:
pass
class FooSub(Foo):
pass
class Bar:
pass
@final
class Baz:
pass
def _(target: FooSub):
y = 1
match target:
case Baz():
y = 2
case Foo():
y = 3
case Bar():
y = 4
reveal_type(y) # revealed: Literal[3]
def _(target: FooSub):
y = 1
match target:
case Baz():
y = 2
case Bar():
y = 3
case Foo():
y = 4
reveal_type(y) # revealed: Literal[3, 4]
def _(target: FooSub | str):
y = 1
match target:
case Baz():
y = 2
case Foo():
y = 3
case Bar():
y = 4
reveal_type(y) # revealed: Literal[1, 3, 4]
Singleton match
Singleton patterns are matched based on identity, not equality comparisons or isinstance() checks.
from typing import Literal
def _(target: Literal[True, False]):
y = 1
match target:
case True:
y = 2
case False:
y = 3
case None:
y = 4
# TODO: with exhaustiveness checking, this should be Literal[2, 3]
reveal_type(y) # revealed: Literal[1, 2, 3]
def _(target: bool):
y = 1
match target:
case True:
y = 2
case False:
y = 3
case None:
y = 4
# TODO: with exhaustiveness checking, this should be Literal[2, 3]
reveal_type(y) # revealed: Literal[1, 2, 3]
def _(target: None):
y = 1
match target:
case True:
y = 2
case False:
y = 3
case None:
y = 4
reveal_type(y) # revealed: Literal[4]
def _(target: None | Literal[True]):
y = 1
match target:
case True:
y = 2
case False:
y = 3
case None:
y = 4
# TODO: with exhaustiveness checking, this should be Literal[2, 4]
reveal_type(y) # revealed: Literal[1, 2, 4]
# bool is an int subclass
def _(target: int):
y = 1
match target:
case True:
y = 2
case False:
y = 3
case None:
y = 4
reveal_type(y) # revealed: Literal[1, 2, 3]
def _(target: str):
y = 1
match target:
case True:
y = 2
case False:
y = 3
case None:
y = 4
reveal_type(y) # revealed: Literal[1]
Or match
A | pattern matches if any of the subpatterns match.
from typing import Literal, final
def _(target: Literal["foo", "baz"]):
y = 1
match target:
case "foo" | "bar":
y = 2
case "baz":
y = 3
# TODO: with exhaustiveness, this should be Literal[2, 3]
reveal_type(y) # revealed: Literal[1, 2, 3]
def _(target: None):
y = 1
match target:
case None | 3:
y = 2
case "foo" | 4 | True:
y = 3
reveal_type(y) # revealed: Literal[2]
@final
class Baz:
pass
def _(target: int | None | float):
y = 1
match target:
case None | 3:
y = 2
case Baz():
y = 3
reveal_type(y) # revealed: Literal[1, 2]
def _(target: None | str):
y = 1
match target:
case Baz() | True | False:
y = 2
case int():
y = 3
reveal_type(y) # revealed: Literal[1, 3]
Guard with object that implements __bool__ incorrectly
class NotBoolable:
__bool__: int = 3
def _(target: int, flag: NotBoolable):
y = 1
match target:
# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`; its `__bool__` method isn't callable"
case 1 if flag:
y = 2
case 2:
y = 3
reveal_type(y) # revealed: Literal[1, 2, 3]