Debugger Issues

[strickdd]

Prerequisites

• I have written a descriptive issue title.
• I have searched all issues to ensure it has not already been reported.
• I have read the troubleshooting guide.
• I have verified that I am using the latest version of Visual Studio Code and the PowerShell extension.

Summary

REF: #3394 (comment)

After attempting to resolve my issue with the pre-release version of the extension, the debugger started failing again. Per @rjmholt 's suggestion, I am opening a new issue for tracking.

PowerShell Version

Both PS 5.1 and 7 have issues.

Name                           Value
----                           -----
PSVersion                      7.1.0
PSEdition                      Core
GitCommitId                    7.1.0
OS                             Microsoft Windows 10.0.18363
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0


Name                           Value                                                                                                                                                                                                                                                                                
----                           -----                                                                                                                                                                                                                                                                                
PSVersion                      5.1.18362.1474                                                                                                                                                                                                                                                                       
PSEdition                      Desktop                                                                                                                                                                                                                                                                              
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}                                                                                                                                                                                                                                                              
BuildVersion                   10.0.18362.1474                                                                                                                                                                                                                                                                      
CLRVersion                     4.0.30319.42000                                                                                                                                                                                                                                                                      
WSManStackVersion              3.0                                                                                                                                                                                                                                                                                  
PSRemotingProtocolVersion      2.3                                                                                                                                                                                                                                                                                  
SerializationVersion           1.1.0.1

Visual Studio Code Version

1.59.1
3866c3553be8b268c8a7f8c0482c0c0177aa8bfa
x64

Extension Version

ms-vscode.powershell@2021.8.0
ms-vscode.powershell-preview@2021.8.1

Steps to Reproduce

Scenario 1 (PowerShell 5.1)

1. Close all VSCode instances
2. Open new instance with no folder opened
3. Create a new PowerShell script
4. Past in script below (do not save)

function Write-SomeStatus {
    # Breakpoint on following line
    Write-Host 'Some Status'
}

Write-SomeStatus

5. Press F5

Expected: Breakpoint is hit
Actual: Breakpoint is skipped and script contents + "Some Status" is written to terminal

Scenario 2 (PowerShell 5.1)

1. Save the script from Scenario 1 to C:\temp\DebuggingTest.ps1
2. Readd the breakpoint to line 3 (as indicated)
3. Press F5
4. Debugger starts and attaches correctly
5. Press F5 to run to completion
6. Run Write-SomeStatus from the terminal directly
7. Debugger attaches to breakpoint at line 3
8. Press F5 to continue and the debugger hangs (screenshot below)

Visuals

Debugger attaches when adding new Write-Host line:

Debugger hangs after calling from terminal directly:

Logs

EditorServices.log
StartEditorServices.log
vscode-powershell.log

[andyleejordan]

Did you try v2021.8.2-preview? There was an issue in v2021.8.1-preview where the debugger "hung" waiting for an enter to actually cancel PSReadLine, #3513.

[strickdd]

Updated to v2021.8.2-preview

ms-vscode.powershell@2021.8.0
ms-vscode.powershell-preview@2021.8.2

Now, here are the results:

Scenario 1 (PowerShell 5.1)

No change, still does not hit the breakpoint

Scenario 2

No change, still hangs with the debug toolbar showing. Pressing "enter" does not continue on or close the debug toolbar

Logs from current run

EditorServices.log
StartEditorServices.log
vscode-powershell.log

[andyleejordan]

Scenario 1 reproduces for me; however, I'd point out that this is debugging an unsaved script. @rjmholt is that something we actively support? I'm not sure how we would, as there is no script file name to pass to the debug adapter.

Scenario 2 also reproduces for me; however, this is again a strange scenario: it's using the PowerShell debugger in the integrated console to start the debugger (which does somehow cause VS Code to recognize the debugger is running), but then when it ends the VS Code debugger doesn't know that the debugging session has finished. @rjmholt is this also something we actively support?

[strickdd]

Scenario 1:
Ref for unsaved debugging:

• https://github.com/PowerShell/vscode-powershell/releases/tag/v2021.5.1
• Don't prompt to save untitled PowerShell files when debugging #3357

Scenario 2:
This is something ISE has always supported, and I believe VSCode has allowed me to do since I switched over. However, I can't confirm how long VSCode has had this functionality.

[andyleejordan]

Digging into this a little bit, Scenario 1 is explicitly only supported in PowerShell 7 and up. It requires the PowerShell breakpoint APIs, which are not available in PowerShell 5.1. And this scenario's issue does not reproduce with PowerShell 7. This should probably be documented somewhere, I found it by looking through PSES.

But I don't understand why that message isn't in your log. I think it's a bug; we should not just emit a warning in the log but we should actively inform the user when you try to debug an untitled file with PowerShell 5.1 that it won't work. And we need a test for that. Moreover, we also need a test that it does work in PowerShell 7.

[strickdd]

Retried Scenario 1 under PS 7 with a slight difference. I modified and debugged an existing file, but did NOT save the file before debugging.

Debugging started, pressed F5, and it entered a "weird" PS file and stops there

Pressing F5 again, I get to another file, but the debugger is "hung"

After it was hung, I pressed the "stop" button on the toolbar and cannot start the debugger anymore. The debug toolbar comes up, but doesn't hit the breakpoint.

[andyleejordan]

I could see Scenario 2 as something that "just worked" in the past. It's good to know that this is functionality you want; it's sad that we did not have tests for it. Because now we'll have to fix it and this time add regression tests. I confirmed it reproduces with both PowerShell 7 and 5.1.

[andyleejordan]

Retried Scenario 1 under PS 7 with a slight difference. I modified and debugged an existing file, but did NOT save the file before debugging.

You should probably save your file before debugging. Again, not sure if that's something we actively support. Breakpoints are set on files with line numbers. In the case of untitled files, I'm not sure how that's implemented; I imagine VS Code is creating a pseudo file for us. The original implementation looked like it guessed that a file was unsaved, and then passed the buffer contents to the debugger directly, which is fragile and probably not how it's done using O#.

[rjmholt]

@rjmholt is that something we actively support?

I didn't think it was in PS 5.1 because there was a whole discussion about the API to support it in PS 7. But our behaviour should do something like reject the breakpoints.

Scenario 2

Is the debugger hanging or just staying on? What is your debug configuration that's running when you hit F5? A PowerShell Interactive Session is supposed to effectively stay open.

The big difference between VSCode and the ISE is VSCode's debug protocol and that fact that its debug client owns the session. So in the ISE, you could place a breakpoint in a file from the UI, hit it from the integrated console and drop into the debugger.

In VSCode, breakpoints placed in the UI only get sent over to the server when the debug client starts, so you'd place a breakpoint, the server would never get told, you'd hit it from the console and no debugger. For that reason the PowerShell Interactive Session was invented, where the debugger is always on, so PSES always gets updated with UI breakpoints. But then your debug session never ends...

Some related issues:

• ISE like breakpoint behaviour (hit breakpoints when running a script from the integrated terminal) #2159
• Reset Session before launching debugger #2411
• Breakpoints not cleaned up if Debug Interactive Session is stopped. #2371
• Debug Session not respecting Added or removed Breakpoints & Integrated Shell Crash #1494
• Break point 'breaks debugging' when disabled during execution #1166

[SeeminglyScience]

In the case of untitled files, I'm not sure how that's implemented; I imagine VS Code is creating a pseudo file for us.

It's identified in VSCode with an ID like untitled:Untitiled-x where x is in incrementing number. On the PowerShell end the Parser.ParseInput(string input, string fileName, ...) overload is used which can attach any arbitrary string to Ast.Extent.File (which is what the engine uses to match line breakpoints to a "file")

[andyleejordan]

I didn't think it was in PS 5.1 because there was a whole discussion about the API to support it in PS 7. But our behaviour should do something like reject the breakpoints.

For what it's worth, it does reject the breakpoint (kind of). It shows up as "unverified" in the editor.

[rjmholt]

For what it's worth, it does reject the breakpoint (kind of). It shows up as "unverified" in the editor.

Yeah that's what I imagined it should do. We still execute the file (since we can) but communicate that we won't honour the breakpoint