bpo-32960: For dataclasses, disallow inheriting frozen from non-frozen classes and vice-versa, (GH-5919)
This restriction will be relaxed at a future date.
diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index db92b10..54478fe 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -623,14 +623,21 @@
else:
setattr(cls, f.name, f.default)
+ # We're inheriting from a frozen dataclass, but we're not frozen.
+ if cls.__setattr__ is _frozen_setattr and not frozen:
+ raise TypeError('cannot inherit non-frozen dataclass from a '
+ 'frozen one')
+
+ # We're inheriting from a non-frozen dataclass, but we're frozen.
+ if (hasattr(cls, _MARKER) and cls.__setattr__ is not _frozen_setattr
+ and frozen):
+ raise TypeError('cannot inherit frozen dataclass from a '
+ 'non-frozen one')
+
# Remember all of the fields on our class (including bases). This
# marks this class as being a dataclass.
setattr(cls, _MARKER, fields)
- # We also need to check if a parent class is frozen: frozen has to
- # be inherited down.
- is_frozen = frozen or cls.__setattr__ is _frozen_setattr
-
# Was this class defined with an explicit __hash__? Note that if
# __eq__ is defined in this class, then python will automatically
# set __hash__ to None. This is a heuristic, as it's possible
@@ -654,7 +661,7 @@
if f._field_type in (_FIELD, _FIELD_INITVAR)]
_set_new_attribute(cls, '__init__',
_init_fn(flds,
- is_frozen,
+ frozen,
has_post_init,
# The name to use for the "self" param
# in __init__. Use "self" if possible.
@@ -696,7 +703,7 @@
f'in class {cls.__name__}. Consider using '
'functools.total_ordering')
- if is_frozen:
+ if frozen:
for name, fn in [('__setattr__', _frozen_setattr),
('__delattr__', _frozen_delattr)]:
if _set_new_attribute(cls, name, fn):