Display message if active file being debugged is not a python file

[DonJayamanne]

This applies to both experimental & current debugger

Very often we have users attempting to debug python code with the launch.json file opened.
In such a situation, launch.json is treated as the active file and python debugger will attempt to debug this.

Proposed solution:

• Display a message if active file is not a python file
• If there are at least 2 python file opened in the editor, then display a file picker (or drop down list), allowing the user to select a file to debug
• If there is only one python file opened in the editor, use that for debugging

This will avoid a lot of confusion amongst users (I've seen our own devs get confused fall into this trap).

Might want to consider getting this into March release.

@brettcannon @qubitron
Thoughts

[qubitron]

@DonJayamanne I think a message is sufficient here: "Your debugging configuration is set to debug the current file, but the current file is not a Python file. Please open a Python file and try again". Once you realize what the problem is it is easy to fix, no need to add UI for displaying a file picker and if we try to be too smart it might be more of a headache to maintain.

[Anapo14]

We could add a link to this. It has info on trying to debug the launch.json file. Users may be curious to learn more.

[cpinamtz]

Does it makes sense to keep this issue opened (at the moment of writing this, VSCode v1.77.0 and vscode-python extension v2023.6.0) when the IDE distinguishes whether the current opened file is or not a Python file to display the Run Python File and sub-option Debug Python File?

[brettcannon]

@cpinamtz thanks for the ping on this! I think you're right it isn't worth keeping open for the reasons you listed and there's only a single upvote after over 5 years.