ruff/crates/ty_python_semantic/resources/mdtest/annotations
Douglas Creager b892e4548e
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[ty] Track when type variables are inferable or not (#19786)
`Type::TypeVar` now distinguishes whether the typevar in question is
inferable or not.

A typevar is _not inferable_ inside the body of the generic class or
function that binds it:

```py
def f[T](t: T) -> T:
    return t
```

The infered type of `t` in the function body is `TypeVar(T,
NotInferable)`. This represents how e.g. assignability checks need to be
valid for all possible specializations of the typevar. Most of the
existing assignability/etc logic only applies to non-inferable typevars.

Outside of the function body, the typevar is _inferable_:

```py
f(4)
```

Here, the parameter type of `f` is `TypeVar(T, Inferable)`. This
represents how e.g. assignability doesn't need to hold for _all_
specializations; instead, we need to find the constraints under which
this specific assignability check holds.

This is in support of starting to perform specialization inference _as
part of_ performing the assignability check at the call site.

In the [[POPL2015][]] paper, this concept is called _monomorphic_ /
_polymorphic_, but I thought _non-inferable_ / _inferable_ would be
clearer for us.

Depends on #19784 

[POPL2015]: https://doi.org/10.1145/2676726.2676991

---------

Co-authored-by: Carl Meyer <carl@astral.sh>
2025-08-16 18:25:03 -04:00
..
annotated.md [ty] Add hints to invalid-type-form for common mistakes (#18543) 2025-06-09 00:40:05 +01:00
any.md [ty] Fix panics when pulling types for various special forms that have the wrong number of parameters (#18642) 2025-06-17 10:40:50 +01:00
callable.md [ty] Fallback to Unknown if no type is stored for an expression (#19517) 2025-07-25 02:05:32 +00:00
deferred.md Rename Red Knot (#17820) 2025-05-03 19:49:15 +02:00
int_float_complex.md [ty] Improve disjointness inference for NominalInstanceTypes and SubclassOfTypes (#18864) 2025-06-24 20:27:37 +00:00
invalid.md [ty] simplify return type of place_from_declarations (#19884) 2025-08-13 14:17:08 +00:00
literal.md Fix panic for illegal Literal[…] annotations with inner subscript expressions (#19489) 2025-07-22 14:07:20 +00:00
literal_string.md Rename Red Knot (#17820) 2025-05-03 19:49:15 +02:00
never.md Rename Red Knot (#17820) 2025-05-03 19:49:15 +02:00
new_types.md ty_python_semantic: add union type context to function call type errors 2025-05-09 13:40:51 -04:00
optional.md Rename Red Knot (#17820) 2025-05-03 19:49:15 +02:00
self.md [ty] Track when type variables are inferable or not (#19786) 2025-08-16 18:25:03 -04:00
starred.md [ty] Return Option<TupleType> from infer_tuple_type_expression (#19735) 2025-08-04 13:48:19 +01:00
stdlib_typing_aliases.md [ty] Support using legacy typing aliases for generic classes in type annotations (#18404) 2025-06-03 12:09:51 +01:00
string.md [ty] Emit error for invalid binary operations in type expressions (#18991) 2025-06-30 10:06:01 +02:00
union.md [ty] Consistent use of American english (in rules) (#19488) 2025-07-22 16:10:38 +02:00
unsupported_special_forms.md [ty] typing.Self is bound by the method, not the class (#19784) 2025-08-06 17:26:17 -04:00
unsupported_special_types.md Generalize special-casing for enums constructed with the functional syntax (#17885) 2025-05-06 11:02:55 +01:00
unsupported_type_qualifiers.md Rename Red Knot (#17820) 2025-05-03 19:49:15 +02:00