Hey all 👋 We have a custom plugin repo that was initially written to support pants 2.19, but now we want to add support for pants 2.24 and I'm seeing some weird

mypy

behavior when running

pants check ::

Partition #1 - pants-2-19, ['CPython==3.9.*']:
<my_file.py>: error: Unexpected keyword argument "paths" for "Sandbox"; did you mean "path"?  [call-arg]
Found 1 error in 1 file (checked 1 source file)

Partition #2 - pants-2-24, ['CPython==3.9.*']:
<my_file.py>: error: Unexpected keyword argument "path" for "Sandbox"; did you mean "paths"?  [call-arg]

My

my_file.py

looks like:

from pants.core.util_rules.adhoc_process_support import ExtraSandboxContents
from pants.version import Version, PANTS_SEMVER

class Sandbox(ExtraSandboxContents):

    @staticmethod
    def from_process(process: Process):
        env_with_out_path: dict[str, str] = dict()
        env_with_out_path.update(process.env)
        env_with_out_path.pop("PATH", None)

        if PANTS_SEMVER < Version("2.23.0"):
            return Sandbox(
                digest=process.input_digest,
                path=process.env.get("PATH", None),   <<< this is the prop when using pants<2.23.0
                immutable_input_digests=process.immutable_input_digests,
                append_only_caches=process.append_only_caches,
                extra_env=FrozenDict(env_with_out_path),
            )

        return Sandbox(
            digest=process.input_digest,
            paths=(process.env.get("PATH", None),),  <<< this is the new propery on pants>=2.23.0
            immutable_input_digests=process.immutable_input_digests,
            append_only_caches=process.append_only_caches,
            extra_env=FrozenDict(env_with_out_path),
        )

I had to add the

if

for the version because the

path

property of

Sandbox

was replaced with

paths

on pants 2.23 via https://github.com/pantsbuild/pants/commit/3b1ffb64bc2332e3925ffba387ce496143a4284d#diff-c440a5c58ef3255b75e7fb16e[…]7e2c3aba4567a95f44fa1edf8a4L139, but it looks like

mypy

is not being able to correctly run taking into consideration the pants version, as it fails on pants 2.19 with

paths

doesn't exist in

Sandbox

, and fails on pants 2.24 with

path

doesn't exist in

Sandbox

. I do have the

resolves

configured for each pants version, so that I can run lint, tests, check, etc, for both pants versions. Does anyone know how to correctly run

mypy

with multiple pants versions?

I think it'll be ~near impossible to get mypy to understand this sort of conditional control flow. That is, mypy would need to know that

PANTS_SEMVER

is connected to the API shape of

Sandbox

. So, I think a

# type: ignore[call-arg]

comment may be your best bet here: overrule mypy because you 'know more'

I see, that makes sense. Thanks for the explanation! Will try the first approach of commenting to ignore that specific rule for now.