language-servers/ruff
1
0
Fork 0
mirror of https://github.com/astral-sh/ruff.git synced 2025-10-31 12:05:57 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 3

[ty] Disallow assignment to Final class attributes (#19457)

Browse source 
## Summary

Emit errors for the following assignments:
```py
class C:
    CLASS_LEVEL_CONSTANT: Final[int] = 1

C.CLASS_LEVEL_CONSTANT = 2
C().CLASS_LEVEL_CONSTANT = 2
```

## Test Plan

Updated and new MD tests
This commit is contained in:
David Peter 2025-07-21 14:27:56 +02:00 • committed by GitHub
parent f063c0e874
commit b6579eaf04
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
3 changed files with 63 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

2
crates/ty_python_semantic/resources/mdtest/dataclasses/dataclasses.md
View file

@ -498,7 +498,7 @@ class C:
reveal_type(C.__init__) # revealed: (self: C, instance_variable_no_default: int, instance_variable: int = Literal[1]) -> None
c = C(1)
# TODO: this should be an error
# error: [invalid-assignment] "Cannot assign to final attribute `instance_variable` on type `C`"
c.instance_variable = 2
```

41
crates/ty_python_semantic/resources/mdtest/type_qualifiers/final.md
View file

@ -170,26 +170,37 @@ Assignments to attributes qualified with `Final` are also not allowed:
```py
from typing import Final
class C:
FINAL_A: Final[int] = 1
FINAL_B: Final = 1
class Meta(type):
META_FINAL_A: Final[int] = 1
META_FINAL_B: Final = 1
class C(metaclass=Meta):
CLASS_FINAL_A: Final[int] = 1
CLASS_FINAL_B: Final = 1
def __init__(self):
self.FINAL_C: Final[int] = 1
self.FINAL_D: Final = 1
self.INSTANCE_FINAL_A: Final[int] = 1
self.INSTANCE_FINAL_B: Final = 1
# TODO: these should be errors (that mention `Final`)
C.FINAL_A = 2
# error: [invalid-assignment] "Object of type `Literal[2]` is not assignable to attribute `FINAL_B` of type `Literal[1]`"
C.FINAL_B = 2
# error: [invalid-assignment] "Cannot assign to final attribute `META_FINAL_A` on type `<class 'C'>`"
C.META_FINAL_A = 2
# error: [invalid-assignment] "Cannot assign to final attribute `META_FINAL_B` on type `<class 'C'>`"
C.META_FINAL_B = 2
# error: [invalid-assignment] "Cannot assign to final attribute `CLASS_FINAL_A` on type `<class 'C'>`"
C.CLASS_FINAL_A = 2
# error: [invalid-assignment] "Cannot assign to final attribute `CLASS_FINAL_B` on type `<class 'C'>`"
C.CLASS_FINAL_B = 2
# TODO: these should be errors (that mention `Final`)
c = C()
c.FINAL_A = 2
# error: [invalid-assignment] "Object of type `Literal[2]` is not assignable to attribute `FINAL_B` of type `Literal[1]`"
c.FINAL_B = 2
c.FINAL_C = 2
c.FINAL_D = 2
# error: [invalid-assignment] "Cannot assign to final attribute `CLASS_FINAL_A` on type `C`"
c.CLASS_FINAL_A = 2
# error: [invalid-assignment] "Cannot assign to final attribute `CLASS_FINAL_B` on type `C`"
c.CLASS_FINAL_B = 2
# TODO: this should be an error
c.INSTANCE_FINAL_A = 2
# TODO: this should be an error
c.INSTANCE_FINAL_B = 2
```
## Mutability