PowerShell dynamic completion script is not valid PowerShell

[jennings]

Please complete the following tasks

• I have searched the discussions
• I have searched the open and rejected issues

Rust Version

rustc 1.83.0 (90b35a623 2024-11-26)

Clap Version

master

Minimal reproducible code

# Sorry for the lack of example, but I think the issue is clear without this.

Steps to reproduce the bug with the above code

Follow the given instructions to install PowerShell dynamic completion:

echo "COMPLETE=powershell your_program | Invoke-Expression" >> $PROFILE

Actual Behaviour

Using the PowerShell dynamic completion installation instructions results in the PowerShell error when the profile loads:

COMPLETE=powershell: The term 'COMPLETE=powershell' is not recognized as a name of a cmdlet, function, script file, or executable program.
Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

Expected Behaviour

The argument completer should be added to the PowerShell environment successfully.

Additional Context

The PowerShell dynamic completion profile script is not valid PowerShell:

$results = Invoke-Expression "{var}=powershell &{completer} -- $($commandAst.ToString())";

These are the main problems:

• COMPLETE=powershell mycommand does not work in PowerShell, there is no way to set environment variables inline like this. Unfortunately, the best solution is probably to assign the env var, run the command, then restore the previous value.
• &{completer} may have double-quotes from the shlex::try_quote(completer) above, which results in a syntax error like this: Invoke-Expression "COMPLETE=powershell "C:\path\to\binary.exe" -- ..."
• When a command is quoted, it needs to be prefixed with the call operator &.
• The AST may include characters that PowerShell interprets, so we need the stop processing operator --%

This should instead be written something like this:

    $completer = {completer}
    $prev = $env:{var}
    $results = Invoke-Expression "& $completer -- --% $commandAst";
    if ($null -eq $prev) {{
        Remove-Item Env:\{var}
    }} else {{
        $env:{var} = $prev
    }}    

In addition, the instructions to install this in the profile are not correct:

echo "COMPLETE=powershell your_program | Invoke-Expression" >> $PROFILE

This has the same inline env var problem, but also PowerShell tries to execute this line by line. It needs to be piped to Out-String:

//! $env:COMPLETE = "powershell"
//! echo "your_program | Out-String | Invoke-Expression" >> $PROFILE
//! Remove-Item Env:\COMPLETE

Debug Output

No response

[epage]

I knew PowerShell support was under-developed when I merged it but I figured it would get overlooked otherwise. For moving this forward, we need someone with PowerShell experience to finish it up.

[jennings]

I don’t think it’s far off, if I put the corrected script in my profile, dynamic completions in jj start working.

I started trying to write the patch, but haven’t had time to figure out how to test it.

[epage]

Let's not hold up working for the sake of testing. All of our old script generators had no tests anyways.