## Summary
closes#16615
This PR includes:
- Introduces a new type: `Type::BoundSuper`
- Implements member lookup for `Type::BoundSuper`, resolving attributes
by traversing the MRO starting from the specified class
- Adds support for inferring appropriate arguments (`pivot_class` and
`owner`) for `super()` when it is used without arguments
When `super(..)` appears in code, it can be inferred into one of the
following:
- `Type::Unknown`: when a runtime error would occur (e.g. calling
`super()` out of method scope, or when parameter validation inside
`super` fails)
- `KnownClass::Super::to_instance()`: when the result is an *unbound
super object* or when a dynamic type is used as parameters (MRO
traversing is meaningless)
- `Type::BoundSuper`: the common case, representing a properly
constructed `super` instance that is ready for MRO traversal and
attribute resolution
### Terminology
Python defines the terms *bound super object* and *unbound super
object*.
An **unbound super object** is created when `super` is called with only
one argument (e.g.
`super(A)`). This object may later be bound via the `super.__get__`
method. However, this form is rarely used in practice.
A **bound super object** is created either by calling
`super(pivot_class, owner)` or by using the implicit form `super()`,
where both arguments are inferred from the context. This is the most
common usage.
### Follow-ups
- Add diagnostics for `super()` calls that would result in runtime
errors (marked as TODO)
- Add property tests for `Type::BoundSuper`
## Test Plan
- Added `mdtest/class/super.md`
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Co-authored-by: Carl Meyer <carl@astral.sh>
649610cc98