Path Mapping on Attach request

[jborean93]

Prerequisites

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Summary

When debugging a remote runspace the current logic is for PSES to retrieve back a temporary file of anything hit in a breakpoint and display it VSCode. This can be prone to some bugs and makes debugging a runspace that is not local a lot more difficult than it has to be.

Other languages work around this issue by offering an option to map local path(s) to their remote equivalent and vice versa.

For example .NET's DAP launch configuration has an option called sourceFileMap. You can do something like

{
    "sourceFileMap": {
        "C:\\remote\\path": "/home/local/path"
    }
}

Python is similar but calls the option pathMappings and uses a different structure. For example:

{
    "pathMappings": [
        {
            "localRoot": "/home/local/path",
            "remoteRoot": "C:\\remote\\path"
        }
    ]
}

I would like to extend the attach request in PSES to support a way to map these local <-> remote paths so we can avoid all the psedit and file copying problems.

Proposed Design

I'm more in favour of the pathMappings option that Python uses as the C# one is more geared around to source compilation paths than actual local/remote translations. It is slightly more verbose but it is easier to see what is the local and what is the remote.

As for the implementation there are a few locations that need to do the translation:

• SetLineBreakpointsAsync when translating the local to remote breakpoint path
• FetchStackFramesAsync when translating the remote stack frame file path to local
• StackTraceHandler.Handle needs to update the breakpoint label

There may be others but I've not yet come across them. The option, if set, should also override the psedit mapping logic as well. Essentially it will treat the paths as local and just translate it to/from the remote paths when needed.

[JustinGrote]

In general we've been holding up the Python extension as a great model for a vscode extension so definitely down to adopt their practices.

[JustinGrote]

So yeah I've considered making something similar to source maps for PS, the hardest thing being that stacktraces are very annoyingly immutable in .NET so there's guaranteed to be some inaccurate information in the debug and whatnot, so we either need to solve all those problems, or disclaim to the user as to the innacurate information that might be present.

[jborean93]

Luckily there's currently logic to rewrite stack traces for the existing temp fetched file from a PSRemoting session. In my POC I mostly just hooked into that to get things working. Granted there may be edge cases I haven't come across yet.