Pylance features are not working when debugger is attached to file outside workspace

[Andrej730]

1. Save the snippet below, set breakpoint at bar() and then run it (not in debug mode).
2. Attach debugger.
3. Try to go to definition for bar or foo. ctrl-click is not working and go to definition is not present in context menu.
4. If you hover over variable it says use 'Alt' to show editor language tooltip but it's not working.
   
5. Syntax highlight itself looks weirdly - apparently the problem is that symbols are not recognizes as such and modules / methods / functions appear just as white, making it harder to read.

Snippet:

import debugpy


def foo():
    print("hello")


def bar():
    foo()


debugpy.listen(5678)
debugpy.wait_for_client()
bar()

Issue demo:

Code_-_Insiders_4bX4iRJKcA.mp4

Expected result (for it to work in similar way to starting debug mode from editor):

Code_-_Insiders_y5fA2ARhqm.mp4

[Andrej730]

I was able to narrow it down further - the issue occurs when python file you attach to is outside the current workspace (justMyCode setting is disabled, so it shoudn't get in the way).

In my case I have a main repository I'm working on (e.g. C:\repo\xxx) and for the development I need to see the changes live as part of another software yyy.
To achieve it, I've symlinked C:\yyy\xxx to C:\repo\xxx. But since I use C:\yyy\main.py to start the program, then from debugger's POV it appears like I'm working with the files outside of my workspace (C:\yyy\xxx), which leads me to this issue.

[eleanorjboyd]

@rchiodo thoughts here? Is this debugpy then since after starting the debugging process or is that link resolution expected to be provided by the debugger extension?

[rchiodo]

This should be a pylance issue. Debugpy doesn't participate in goto def. My only guess is that the file opened by the debugger doesn't have a 'file' scheme, so Pylance doesn't understand it. It sure looks like it does, but it would be hard to tell just from the UI.

Setting "python.trace.server": "compact" should output in the pylance log what the URI is being sent for the goto def command.