[ty] support super() in metaclass methods#24483
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Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 87.72%. The percentage of expected errors that received a diagnostic held steady at 82.85%. The number of fully passing files held steady at 74/132. |
Memory usage reportMemory usage unchanged ✅ |
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charliermarsh
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Apr 8, 2026
AlexWaygood
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Apr 8, 2026
AlexWaygood
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Apr 9, 2026
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| pub(crate) fn as_type(self, db: &'db dyn Db) -> Type<'db> { | ||
| match self { | ||
| TypeVarBoundOrConstraints::UpperBound(bound) => bound, | ||
| TypeVarBoundOrConstraints::Constraints(constraints) => constraints.as_type(db), | ||
| } | ||
| } |
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I worry that this method will be a bit of a performance footgun, because it's a very convenient API, but TypeVarConstraints::as_type (which invokes the UnionBuilder) seems unnecessarily expensive for lots of operations where you can get the same result by explicitly mapping over the typevar constraints
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I see that, but I'm not sure it justifies not providing the method, when we have valid use cases for it. What would you suggest? I can add a doc comment to it.
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
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* main: [ty] Fix bad diagnostic range for incorrect implicit `__init_subclass__` calls (#24541) [ty] Add a `SupportedPythonVersion` enum (#24412) [ty] Ignore unsupported editor-selected Python versions (#24498) [ty] Add snapshots for `__init_subclass__` diagnostics (#24539) [ty] Minor fix in tests (#24538) [ty] Allow `Final` variable assignments in `__post_init__` (#24529) [ty] Expand test suite for assignment errors (#24537) [ty] Use `map`, not `__map`, as the name of the mapping parameter in `TypedDict` `__init__` methods (#24535) [ty] Rework logic for synthesizing `TypedDict` methods (#24534) [flake8-bandit] Fix S103 false positives and negatives in mask analysis (#24424) [ty] mdtest.py: update dependencies (#24533) Rename patterns and arguments source order iterator method (#24532) [ty] Omit invalid keyword arguments from `TypedDict` signature (#24522) [ty] support super() in metaclass methods (#24483) [ty] Synthesize `__init__` for `TypedDict` (#24476)
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* main: Bump typing conformance suite commit to latest upstream (#24553) [ty] Reject deleting`Final` attributes (#24508) [ty] Respect property deleters in attribute deletion checks (#24500) [ty] stop unioning Unknown into types of un-annotated attributes (#24531) [ty] Fix bad diagnostic range for incorrect implicit `__init_subclass__` calls (#24541) [ty] Add a `SupportedPythonVersion` enum (#24412) [ty] Ignore unsupported editor-selected Python versions (#24498) [ty] Add snapshots for `__init_subclass__` diagnostics (#24539) [ty] Minor fix in tests (#24538) [ty] Allow `Final` variable assignments in `__post_init__` (#24529) [ty] Expand test suite for assignment errors (#24537) [ty] Use `map`, not `__map`, as the name of the mapping parameter in `TypedDict` `__init__` methods (#24535) [ty] Rework logic for synthesizing `TypedDict` methods (#24534) [flake8-bandit] Fix S103 false positives and negatives in mask analysis (#24424) [ty] mdtest.py: update dependencies (#24533) Rename patterns and arguments source order iterator method (#24532) [ty] Omit invalid keyword arguments from `TypedDict` signature (#24522) [ty] support super() in metaclass methods (#24483) [ty] Synthesize `__init__` for `TypedDict` (#24476)
ibraheemdev
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Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
This was referenced Apr 27, 2026
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Summary
Fixes astral-sh/ty#3231.
Explicit
super()calls come in two varieties (zero-argumentsuper()is just syntactic sugar for the two explicit forms, with the arguments automatically derived from context):super(ThisClass, instance), whereinstancemust be an instance ofThisClass; this is typically found in instance methods as e.g.super(ThisClass, self), orsuper(ThisClass, SubClass), whereSubClassmust be a subclass ofThisClass; this is typically found in classmethods, as e.g.super(ThisClass, cls).The two cases are handled distinctly at runtime. In the first case we look for
ThisClass(the "pivot class") in the MRO oftype(instance)to decide where to start our MRO walk; in the second case we look for the pivot in the MRO ofSubClassitself (not its type).We previously distinguished these cases by checking whether the second argument (
owner) was a class or not. This fails in the case ofsuper()calls in a metaclass, where the second argument can be a class, but we may still have the "instance" form ofsuper, because the first argument is a metaclass. For example, we havesuper(ThisMetaClass, cls), whereclsis a class, but it is an instance ofThisMetaClass, not a subclass of it.This PR refactors our representation of bound super objects to more clearly represent these two varieties, and more closely match the runtime representation, while eliminating some distinctions we previously tracked as variants of
SuperOwnerKindthat aren't actually necessary to correctly implementing the semantics.Test Plan
Passes all existing tests, plus newly added mdtests for metaclass
super()which fail on main.