Adopt vscode.env.shell

[Tyriar]

This new API was added since terminal.integrated.shell.* now defaults to null. microsoft/vscode#75091

I recommend adopting env.shell and use that when it's available and remove the default shell detection logic added in #5886 in a few months and instead fallback to very basic detection (cmd, bash || sh)

[DonJayamanne]

@Tyriar Thanks for the API, I'v been monitoring this in another issue.
Either way, is this API expected to get into the stable version of VSC in the next release? If not, then I'd rather wait before we took any action at our end.

[Tyriar]

@DonJayamanne proposed next version, stable in the following if all is well.

[Tyriar]

@DonJayamanne please adopt this before it goes stable, basically the only point of the proposed period is for you to report issues with it.

[DonJayamanne]

Prescribed Solution

• Modify https://github.com/microsoft/vscode-python/blob/114ee5eeb839f529da53b9e7f28eaf588ca1ba30/src/client/common/terminal/shellDetector.ts

        // Step 1. Determine shell based on the name of the terminal.
        if (terminal) {
            shell = this.identifyShellByTerminalName(terminal.name, telemetryProperties);
        }

        // Step 2. use VSCode API To get shell
        if (shell === TerminalShellType.other){
            shell = this.identifyShellByTerminalName(vscode.env.shell, telemetryProperties);
        }

• Modify https://github.com/microsoft/vscode-python/blob/14ffa656342c61df711638577f8f67376fc1a11d/src/client/common/application/applicationEnvironment.ts

    public get shell(): string {
        // tslint:disable-next-line: no-any
        return (vscode.env as any).shell;
    }

[DonJayamanne]

To validate:

• Use VSC Insiders

[kimadeline]

What I did (VS Code Insiders, extension built from commit 47db2f7):

• open a project folder with a virtual environment in it
• after extension activation, open a terminal and check that the virtual environment gets activated

✅ What worked:

• macOS - bash
• macOS - sh
• macOS - zsh

❌ What didn't work:

• Windows - Git bash:
  

• Windows - cmd:
  

• Windows - WSL: not the same error message as in latest extension release + VS Code stable

  • Stable:
    

  • Insiders + 47db2f7:
    

⚠️ Powershell didn't work, but it is not caused by the extension (env could not be activated automatically, see #6434)

[kimadeline]

Second validation pass:

• macOS - bash
• macOS - sh
• macOS - zsh
• Windows - Git bash
• Windows - cmd
• Windows - WSL

[kimadeline]

✅ validated

[DonJayamanne]

@Tyriar using this API causes VSCode to display a message about using experimental API in stable mode (fyi - I've added a try..catch guard, however that doesn't fix it).
Will be removing the code for now.

I was wrong, it works as expected.