Type aliases not marked as such

[denisw]

The httpx2._types module (re-exported by httpx2) contains several type aliases such as QueryParamTypes, defined like so:

QueryParamTypes = Union[
    "QueryParams",
    Mapping[str, PrimitiveData | Sequence[PrimitiveData]],
    list[tuple[str, PrimitiveData]],
    tuple[tuple[str, PrimitiveData], ...],
    str,
    bytes,
]

The issue is that these aliases are not marked as such, neither using typing.TypeAlias (availabl since Python 3.10) nor with the type statement introduced in Python 3.12. This results in e.g. ty complaining "Variable of type object is not allowed in a parameter annotation" when trying to use one of these meant-to-be type aliases as a function parameter type.

Given that Python 3.10 is the declared minimum Python version for httpx2 currently, my suggestion would be to annotate these aliases with TypeAlias, e.g.:

QueryParamTypes: TypeAlias = Union[...]

[harshagarwalnyu]

You are right, the aliases in src/httpx2/httpx2/_types.py are all plain assignments:

QueryParamTypes = Union[
    "QueryParams",
    Mapping[str, PrimitiveData | Sequence[PrimitiveData]],
    ...
]

mypy and pyright infer implicit type aliases heuristically, which is why they stay quiet, but stricter checkers like ty want the explicit PEP 613 form before they treat the name as an alias rather than a module-level variable. That matters extra here because most of these unions contain forward-reference strings like "QueryParams".

Since the package declares requires-python >= 3.10, the 3.12 type statement is out, but PEP 613 works fine:

from typing import TypeAlias

QueryParamTypes: TypeAlias = Union[
    "QueryParams",
    Mapping[str, PrimitiveData | Sequence[PrimitiveData]],
    list[tuple[str, PrimitiveData]],
    tuple[tuple[str, PrimitiveData], ...],
    str,
    bytes,
]

Mechanical change across the ~15 aliases in that file, no runtime impact. Seems like a reasonable small PR if the maintainers are open to it.