Fix bash -c argument splitting in kernel config step

[gfnord]

What

Fixes a PowerShell parsing bug that made Install-Waydroid.ps1 fail at the "Configuring kernel" step with:

./scripts/config --set-val CONFIG_ANDROID_BINDER_IPC y : -c: line 2: syntax error: unexpected end of file
Command failed (exit 2): wsl -d <distro> -e bash -c cd ~/src/wsl-kernel && ...

Why

The kernel config command was built by concatenating string fragments inside an @(...) array literal:

Invoke-Wsl @("-d", $DistroName, "-e", "bash", "-c",
    "cd ~/src/wsl-kernel && zcat /proc/config.gz > .config && " +
    "./scripts/config --set-val CONFIG_ANDROID_BINDER_IPC y " +
    ...)

In PowerShell a newline inside an array literal separates elements, so a trailing + does not continue the expression. That array parses to 12 elements, not 6 — verified:

count=12
[-d] [X] [-e] [bash] [-c]
[cd ~/src/wsl-kernel && zcat /proc/config.gz > .config ]
[./scripts/config --set-val CONFIG_ANDROID_BINDER_IPC y ]
...

So bash -c received only the first fragment — a script ending in a dangling && — hence the syntax error. The remaining fragments were passed as $0, $1, …, which is why the error message quotes ./scripts/config --set-val CONFIG_ANDROID_BINDER_IPC y as the shell name.

A useful tell in the failing output: the echoed command line has doubled spaces at each fragment boundary, because Write-Info renders $WslArgs -join ' ' and each fragment already ended in a space.

How

Build the command in a $configCmd variable using backtick line continuations (which do continue across newlines), then pass it as a single argument. Added a comment explaining the trap so it doesn't get reintroduced.

Verification

• [System.Management.Automation.Language.Parser]::ParseFile on the edited script: no errors.
• The argument array now parses to 6 elements, with the full one-line command in the last one.
• Ran the fixed command against a real wsl-kernel clone (Ubuntu WSL2 distro): exit 0, make olddefconfig completed, and .config contains:

  CONFIG_ANDROID_BINDER_IPC=y
  CONFIG_ANDROID_BINDERFS=y
  CONFIG_ANDROID_BINDER_DEVICES="binder,hwbinder,vndbinder"
  

Notes for the reviewer

• I grepped both Install-Waydroid.ps1 and Uninstall-Waydroid.ps1 for the same pattern (a line ending in + inside an array literal). This was the only occurrence.
• Behavior is otherwise unchanged — same command text, same options, just delivered as one argv entry.