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Fix inheriting from generic @frozen attrs class #15700

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merged 3 commits into from Aug 12, 2023
Merged

Fix inheriting from generic @frozen attrs class #15700

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3b9a4c5
Add regression test
ikonst Jul 18, 2023
cb188b4
Fix
ikonst Jul 18, 2023
bdda350
add converter to testFrozenInheritFromGeneric
ikonst Jul 31, 2023
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2 changes: 1 addition & 1 deletion mypy/plugins/attrs.py
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Expand Up @@ -803,7 +803,7 @@ def _make_frozen(ctx: mypy.plugin.ClassDefContext, attributes: list[Attribute])
else:
# This variable belongs to a super class so create new Var so we
# can modify it.
var = Var(attribute.name, ctx.cls.info[attribute.name].type)
var = Var(attribute.name, attribute.init_type)
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Actually, this is problematic with converters, e.g.

def converter(s: str) -> int:
    return int(s)

@attrs.define
class C:
    x: int = attrs.field(converter=converter)

The attribute.init_type will be str here :(

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Ahh, nm, by the time it's deserialized, it's int again (there's also converter_init_type).

var.info = ctx.cls.info
var._fullname = f"{ctx.cls.info.fullname}.{var.name}"
ctx.cls.info.names[var.name] = SymbolTableNode(MDEF, var)
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24 changes: 24 additions & 0 deletions test-data/unit/check-plugin-attrs.test
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Expand Up @@ -2250,3 +2250,27 @@ c = attrs.assoc(c, name=42) # E: Argument "name" to "assoc" of "C" has incompat

[builtins fixtures/plugin_attrs.pyi]
[typing fixtures/typing-medium.pyi]

[case testFrozenInheritFromGeneric]
from typing import Generic, TypeVar
from attrs import field, frozen

T = TypeVar('T')

def f(s: str) -> int:
...

@frozen
class A(Generic[T]):
x: T
y: int = field(converter=f)

@frozen
class B(A[int]):
pass

b = B(42, 'spam')
reveal_type(b.x) # N: Revealed type is "builtins.int"
reveal_type(b.y) # N: Revealed type is "builtins.int"

[builtins fixtures/plugin_attrs.pyi]