[Feature Request] Support dmypy `--status-file` flag

[Jasha10]

Hello,

I'd like to request support for setting the dmypy --status-file flag via the pylsp-mypy.cfg file.

The use case is to ensure that multiple instances of the dmypy server do not collide with eachother.

Desired behavior:

Setting e.g. "dmypy_status_file": ".dmypy-pylsp.json" in the pylsp-mypy.cfg file should cause this plugin's invocations of dmypy to pass an argument --status-file=.dmypy-pylsp.json.

[Jasha10]

One might think that the overrides key in the .pylsp-mypy.cfg could handle this use-case, but it does not, because the overrides are not consistently applied for all calls to dmypy. For example, the calls mypy_api.run_dmypy(["status"]) and mypy_api.run_dmypy(["kill"]) in this plugin's pylsp_lint function do not take into account the overrides.

The --status-file argument would need to be passed in consistently across all calls to dmypy.

[Richardk2n]

So passing the overrides consistently would also resolve this?

[Jasha10]

I do not think the overrides should be passed consistently.

Overrides that work with dmypy run -- src will not always work with dmypy status and dmypy kill. For example, dmypy run -- src --check-untyped-defs makes sense but dmypy kill --check-untyped-defs does not make sense.

Also, the --status-file flag needs to be passed to dmypy before the status or kill or run argument:

dmypy --status-file=foo run -- src  # this works
dmypy run --status-file=foo -- src  # this fails with an error
dmypy run -- src --status-file=foo  # this fails with an error

We would need to implement a separate dmypy_overrides configuration parameter that gets always passed to dmypy calls, even when the more general overrides parameter does not apply.

    ...
    # passing dmypy_overrides only:
    mypy_api.run_dmypy([*dmypy_overrides, "status"])
    ...
    # killing the daemon:
    mypy_api.run_dmypy([*dmypy_overrides, "kill"])
    ...
    # passing both dmypy_overrides and normal args+overrides:
    mypy_api.run_dmypy([*dmypy_overrides, "run", "--", *run_args])

[Jasha10]

@Richardk2n I'd be happy to open a PR implementing dmypy_overrides.

[Richardk2n]

Are there such overrides other than the status file that are relevant and are passed in this matter?

(asking for if we should implement and overrides dict or just the flag)

[Jasha10]

Good question. After looking through the other dmypy flags (here's a full list), I think only the --status-file flag makes sense to pass in this manner.

• The --log-file flag could be passed in this manner, but --log-file controls the destination of stdout/stderr. Passing --log-file via pylsp-mypy doesn't make sense since pylsp-mypy already handles dmypy's output streams itself.
• All the other flags (besides --status-file and --log-file) appear to be supported by only a subset of the dmypy commands, e.g. the --timeout flag only works with dmypy start / dmypy restart / dmypy run. This means e.g. applying --timeout=10 to dmypy kill or dmypy status wouldn't make sense. Thus --timeout would not work with an overrides dict.