Fix ground truth for inheritance/MRO benchmarks (Liskov substitution)

[jaltmayerpizzorno]

Hi! Thanks again for creating and maintaining TypeEvalPy — it has been an invaluable resource for our work evaluating type inference tools.

While running the benchmarks, we noticed that 5 inheritance/MRO ground truth annotations use only each method body's return type, without accounting for the Liskov substitution principle. When annotated as given, mypy --strict reports incompatible override errors on all of them. Widening the parent method return types to include the subclass override types resolves this and makes the annotations consistent with what a type-safe program requires.

Affected benchmarks

Benchmark	Function	Before	After
classes/inheritance_overriding	MyClass.func	str	int|str
mro/parents_same_superclass	A.func	str	int|str
mro/self_assignment	B.func	int	int|str
mro/two_parents	B.func	str	int|str
mro/two_parents_method_defined	A.func	float	float|str
mro/two_parents_method_defined	B.func	int	int|str

Note: B.func in two_parents_method_defined is widened to int|str (not float|int|str), because float comes from A.func and A is not in B's class hierarchy — they are unrelated sibling co-parents of C. The LSP widening should only include overrides from B's own subclass chain.

We verified with mypy --strict that the original annotations produce override errors and the corrected ones pass cleanly.

Thanks for considering this!

[Copilot]

Pull request overview

Updates TypeEvalPy micro-benchmark ground-truth annotations for inheritance/MRO cases so method return types respect Liskov substitution (i.e., base method types are widened to accommodate override return types), aligning the benchmarks with what a type-safe program requires under strict type checking.

Changes:

• Widen base-class method return types in inheritance overriding to include subclass override return types.
• Adjust MRO/multiple-inheritance ground truth return types to avoid incompatible override relationships.
• Expand affected main_gt.json entries to represent unions of valid polymorphic return types.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
micro-benchmark/python_features/mro/two_parents_method_defined/main_gt.json	Widens A.func and B.func return types to unions to account for overrides in the hierarchy.
micro-benchmark/python_features/mro/two_parents/main_gt.json	Widens B.func return type to include the type introduced via MRO in subclass C.
micro-benchmark/python_features/mro/self_assignment/main_gt.json	Widens B.func return type to include the subclass override type.
micro-benchmark/python_features/mro/parents_same_superclass/main_gt.json	Widens A.func return type to include the overriding subclass return type.
micro-benchmark/python_features/classes/inheritance_overriding/main_gt.json	Widens MyClass.func return type to include the subclass override type.

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