mirror of
https://github.com/astral-sh/ruff.git
synced 2025-08-10 05:39:12 +00:00
0ede831a3f
## Summary Add a new diagnostic hint if you try to use PEP 604 `X | Y` union syntax in a non-type-expression before 3.10. closes https://github.com/astral-sh/ty/issues/437 ## Test Plan New snapshot test
3.5 KiB
3.5 KiB
Assignment with annotations
Annotation only transparent to local inference
x = 1
x: int
y = x
reveal_type(y) # revealed: Literal[1]
Violates own annotation
x: int = "foo" # error: [invalid-assignment] "Object of type `Literal["foo"]` is not assignable to `int`"
Violates previous annotation
x: int
x = "foo" # error: [invalid-assignment] "Object of type `Literal["foo"]` is not assignable to `int`"
Tuple annotations are understood
[environment]
python-version = "3.12"
module.py:
from typing_extensions import Unpack
a: tuple[()] = ()
b: tuple[int] = (42,)
c: tuple[str, int] = ("42", 42)
d: tuple[tuple[str, str], tuple[int, int]] = (("foo", "foo"), (42, 42))
e: tuple[str, ...] = ()
f: tuple[str, *tuple[int, ...], bytes] = ("42", b"42")
g: tuple[str, Unpack[tuple[int, ...]], bytes] = ("42", b"42")
h: tuple[list[int], list[int]] = ([], [])
i: tuple[str | int, str | int] = (42, 42)
j: tuple[str | int] = (42,)
script.py:
from module import a, b, c, d, e, f, g, h, i, j
reveal_type(a) # revealed: tuple[()]
reveal_type(b) # revealed: tuple[int]
reveal_type(c) # revealed: tuple[str, int]
reveal_type(d) # revealed: tuple[tuple[str, str], tuple[int, int]]
reveal_type(e) # revealed: tuple[str, ...]
reveal_type(f) # revealed: @Todo(PEP 646)
reveal_type(g) # revealed: @Todo(PEP 646)
reveal_type(h) # revealed: tuple[list[int], list[int]]
reveal_type(i) # revealed: tuple[str | int, str | int]
reveal_type(j) # revealed: tuple[str | int]
Incorrect tuple assignments are complained about
# error: [invalid-assignment] "Object of type `tuple[Literal[1], Literal[2]]` is not assignable to `tuple[()]`"
a: tuple[()] = (1, 2)
# error: [invalid-assignment] "Object of type `tuple[Literal["foo"]]` is not assignable to `tuple[int]`"
b: tuple[int] = ("foo",)
# error: [invalid-assignment] "Object of type `tuple[list[Unknown], Literal["foo"]]` is not assignable to `tuple[str | int, str]`"
c: tuple[str | int, str] = ([], "foo")
PEP-604 annotations are supported
def foo(v: str | int | None, w: str | str | None, x: str | str):
reveal_type(v) # revealed: str | int | None
reveal_type(w) # revealed: str | None
reveal_type(x) # revealed: str
PEP-604 in non-type-expression context
In Python 3.10 and later
[environment]
python-version = "3.10"
IntOrStr = int | str
Earlier versions
[environment]
python-version = "3.9"
# error: [unsupported-operator]
IntOrStr = int | str
Attribute expressions in type annotations are understood
import builtins
int = "foo"
a: builtins.int = 42
# error: [invalid-assignment] "Object of type `Literal["bar"]` is not assignable to `int`"
b: builtins.int = "bar"
c: builtins.tuple[builtins.tuple[builtins.int, builtins.int], builtins.int] = ((42, 42), 42)
# error: [invalid-assignment] "Object of type `Literal["foo"]` is not assignable to `tuple[tuple[int, int], int]`"
c: builtins.tuple[builtins.tuple[builtins.int, builtins.int], builtins.int] = "foo"
Future annotations are deferred
from __future__ import annotations
x: Foo
class Foo: ...
x = Foo()
reveal_type(x) # revealed: Foo
Annotations in stub files are deferred
x: Foo
class Foo: ...
x = Foo()
reveal_type(x) # revealed: Foo
Annotated assignments in stub files are inferred correctly
x: int = 1
reveal_type(x) # revealed: Literal[1]