[DeusData]

What

super() binds to the enclosing class's method resolution order, which is Python's C3 linearization. In
that order a common base follows every class that derives from it:

class RadarrCalendarEntity(RadarrEntity, CalendarEntity):
    # MRO: RadarrCalendarEntity, RadarrEntity, CoordinatorEntity, ..., CalendarEntity, Entity
    def _async_write_ha_state(self):
        super()._async_write_ha_state()   # CalendarEntity's override, not Entity's

The super() resolver walked the bases one at a time, each through its whole ancestry. So the first base
reached the shared Entity through CoordinatorEntity before CalendarEntity, which overrides it, was
ever looked at. For super().__init__() it consulted only the first base. When that base was a mixin
without a constructor, it synthesized <mixin>.__init__, a QN that matches no node, and the call was
dropped.

py_lsp.c now computes the C3 order. py_c3_linearize memoizes per lookup, is capped in depth and length,
and reports when a hierarchy has no C3 order. super() takes the first class after the enclosing class that
declares the member itself. A hierarchy without a C3 order keeps the previous base-by-base walk, and so does
the synthesized constructor of an undeclared __init__. Ordinary attribute lookup is unchanged.

No index-format change.

Evidence

Base main 1346ac4 vs this change, 26 Python repos (manifest v1), production builds, macOS arm64,
--repeat 2, every repeat byte-identical.

type	base	this PR	+added	-removed
CALLS	1,355,020	1,355,102	129	47

Every other edge type is identical, apart from SEMANTICALLY_RELATED, which is derived from the CALLS
neighbourhoods. All added edges are lsp_super (54) or lsp_super_init (75).

• Retargeted (47, same call line, new target): the C3 target is a class nearer in the MRO than the shared
  base the old walk reached first. Examples:
  • scikit-learn HuberRegressor.__sklearn_tags__ reaches RegressorMixin, not BaseEstimator.
  • sqlalchemy MSDialect.do_savepoint and MSDialect_pyodbc.do_executemany reach DefaultDialect, not
    the engine.interfaces.Dialect stub.
  • home-assistant Airtouch5AC.async_added_to_hass reaches Airtouch5Entity, not helpers.entity.Entity.
  • matplotlib FigureCanvasQTCairo.draw reaches FigureCanvasQT.draw.
  • pandas StringArray.__setitem__ reaches NDArrayBackedExtensionArray.
  • mypy CallableType.__init__ reaches FunctionLike.__init__.
• New (82, mostly lsp_super_init): super().__init__() in classes whose first base is a mixin without a
  constructor. Examples:
  • scikit-learn AdaBoostRegressor / AdaBoostClassifier reach BaseWeightBoosting.__init__.
  • django AdminUserCreationForm reaches BaseUserCreationForm.__init__, and GIS Scale reaches
    GeoFuncMixin.__init__.
  • sqlalchemy Update reaches ValuesBase.__init__.
• The radarr case itself: on main it already resolves to CalendarEntity, but only because
  RadarrEntity's ancestry is unresolved. Once relative imports resolve (fix(python): from . import x names the importing package, not its parent #2680), main resolves it to
  Entity._async_write_ha_state, and with this change to CalendarEntity._async_write_ha_state (checked
  on home-assistant with both changes merged).

Tests

• pipeline_python_super_follows_c3_mro{,_parallel}: the radarr shape across two files.
  super().write_state() and super().__init__() reach CalendarEntity, never Entity, and a
  single-inheritance class is the control. Sequential and parallel. RED without the fix (ASSERT(m_c3)).
• Affected suites (complexity, extraction, registry, pipeline, cross_repo, py_lsp, py_lsp_stress,
  py_lsp_scale, py_lsp_bench, lsp_resolution_probe, edge_types_probe, convergence_probe,
  matrix_known_classes, parallel, incremental, integration) pass.