[BUG]: Invalid typing for std::array?

[Holt59]

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Problem description

When returning a std::array, the typing information is invalid, e.g. List[str[2]] for the code below. This causes tool such as mypy's stubgen or pybind11-stubgen to produce invalid stubs.

I guess it would be valid to generate List[str] in this case since Python does not have information about the size anyway?

Reproducible example code

#include <pybind11/pybind11.h>
#include <pybind11/stl.h>

namespace py = pybind11;

PYBIND11_MODULE(cpp_module, m)
{
    m.def("arr", []() -> std::array<const char*, 2> {
        return {"foo", "bar"};
    });
}

[bricerebsamen]

@sizmailov for your attention please

[Skylion007]

Oddly enough, this is expected and tested behavior:

pybind11/tests/test_stl.py

Line 42 in 75007dd

assert doc(m.cast_array) == "cast_array() -> List[int[2]]"

. @rwgk @henryiii This doesn't seem to be a valid typing extension. Any idea why this data is included? We can use Annotated, but we need typing_extensions to backport that behavior. I guess we should remove that data or change the return type of a caster to a tuple / something that can handle it?

[Skylion007]

@henryiii Any idea how we can support typing extensions?