Multi-process debugging: dap-python and debugpyAttach/startDebugging about dap-mode HOT 7 OPEN

I noticed in the latest dap-mode code - testing and integrating some of my changes there is support for the startDebugging request. This isn't enabled within the initialisation parameters and also currently doesn't work with debugpy. The processing filter returns:

error in process filter: or: :debugServer or :dap-server-path should be present
error in process filter: :debugServer or :dap-server-path should be present

I'm not sure what the current status of this work is? For this to work dap-server-path would have to be nil and debugServer should be set to the port from the original message. Looks like this function was added as part of 'Initial integration of new node js debugger' by @yyoncho .

from dap-mode.

This is an example startDebugging request message sent by debugpy in a multi-process scenario. In this case the launch-args are different from the scenario tested with the node js debugger. Here we may have launched a process with a straight command line (no attach), but the second process spawned is now requesting that we create a new session and attach to the sub-process.

{
  "seq": 22,
  "type": "request",
  "command": "startDebugging",
  "arguments": {
    "request": "attach",
    "configuration": {
      "type": "python-run-with-python-path",
      "name": "Subprocess 21490",
      "module": "package.runner",
      "cwd": "/home/dsyzling/dev/dap-multi-process",
      "python": [
        "/home/dsyzling/miniconda3/envs/dap-multi-process/bin/python"
      ],
      "isOutputRedirected": null,
      "subProcessId": 21490,
      "connect": {
        "host": "127.0.0.1",
        "port": 57819
      }
    }
  }
}

from dap-mode.

Something like this (excuse the poor emacs lisp and dash binding), which checks to see if there's a nested "connect" key and uses this to initiate the new session. However I think this still fails when the child session terminates and doesn't restore the current connection back to the parent?

(lsp-defun dap--start-debugging ((debug-session &as &dap-session 'launch-args 'proc 'name)
                                 (&hash "seq" "arguments"
                                        (&hash "configuration" (&hash "connect")
                                               "request" "configuration")))
  (-let* (((&plist :debugServer port :host) launch-args)
          (new-launch-args (list
                            :host (if connect (gethash "host" connect) host)
                            :debugServer (if connect (gethash "port" connect) port)
                            :request request
                            :name (format "Child of %s" name))))
    (ht-aeach (plist-put new-launch-args (intern (concat ":" key)) value) configuration)
    (dap-start-debugging-noexpand new-launch-args)

    (dap--send-message (dap--make-success-response
                        seq "startDebugging")
                       (dap--resp-handler) debug-session)))

from dap-mode.