Support for annotated_types

Pycroscope supports the annotated-types library, which provides a set of common primitives to use in Annotated metadata.

This is useful for restricting the value of an object:

from typing_extensions import Annotated
from annotated_types import Gt

def takes_gt_5(x: Annotated[int, Gt(5)]) -> None:
    assert x > 5, "number too small"

def caller() -> None:
    takes_gt_5(6)  # ok
    takes_gt_5(5)  # type checker error

Pycroscope enforces these annotations strictly: if it cannot determine whether or not a value fulfills the predicate, it shows an error. For example, the following will be rejected:

def caller(i: int) -> None:
    takes_gt_5(i)  # type checker error, as it may be less than 5

Notes on specific predicates

Pycroscope infers the interval attributes Gt, Ge, Lt, and Le based on comparisons with literals:

def caller(i: int) -> None:
    takes_gt_5(i)  # error

    if i > 5:
        takes_gt_5(i)  # accepted

Similarly, pycroscope infers the MinLen and MaxLen attributes after checks on len(). For tuple types, pycroscope narrows using these bounds:

• when both bounds imply an exact length, it narrows to a concrete fixed tuple shape (for example, tuple[int, ...] becomes tuple[int, int] after if len(x) == 2:)

• when a lower bound alone is available, it can still refine tuple structure (for example, tuple[*tuple[int, ...], str] becomes tuple[int, *tuple[int, ...], str] after if len(x) >= 2:)

Internally these checks are modeled as intersections with length predicates, which also allows narrowing of other values (for example, literal strings) and eliminates impossible TypedDict branches based on length constraints.

For the MultipleOf check, pycroscope follows Python semantics: values are accepted if value % multiple_of == 0.

For the Timezone check, support for requiring string-based timezones is not implemented.