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[attrs] Fix incorrect handling of attrib with init=False and default #5154

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Merged
merged 1 commit into from
Jun 5, 2018
Merged

[attrs] Fix incorrect handling of attrib with init=False and default #5154

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11 changes: 6 additions & 5 deletions mypy/plugins/attrs.py
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Original file line number Diff line number Diff line change
Expand Up @@ -240,11 +240,12 @@ def _analyze_class(ctx: 'mypy.plugin.ClassDefContext', auto_attribs: bool) -> Li
# attributes for all classes have been read, because subclasses can override parents.
last_default = False
for attribute in attributes:
if attribute.init and not attribute.has_default and last_default:
ctx.api.fail(
"Non-default attributes not allowed after default attributes.",
attribute.context)
last_default = attribute.has_default
if attribute.init:
if not attribute.has_default and last_default:
ctx.api.fail(
"Non-default attributes not allowed after default attributes.",
attribute.context)
last_default |= attribute.has_default

return attributes

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13 changes: 13 additions & 0 deletions test-data/unit/check-attr.test
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Expand Up @@ -844,3 +844,16 @@ class A:
x: int = attr.ib(factory=list) # E: Incompatible types in assignment (expression has type "List[T]", variable has type "int")
y: str = attr.ib(factory=my_factory) # E: Incompatible types in assignment (expression has type "int", variable has type "str")
[builtins fixtures/list.pyi]

[case testAttrsDefaultAndInit]
import attr

@attr.s
class C:
a = attr.ib(init=False, default=42)
b = attr.ib() # Ok because previous attribute is init=False
c = attr.ib(default=44)
d = attr.ib(init=False) # Ok because this attribute is init=False
e = attr.ib() # E: Non-default attributes not allowed after default attributes.

[builtins fixtures/bool.pyi]