Function dirty_source 

pub fn dirty_source(
    git_dir: &Path,
    common_dir: &Path,
    why: CleanRefusal,
) -> Result<DirtySource, CleanRefusal>

What: For a worktree check_clean refused with the ordinary change why, what HEAD names, or the refusal that a restore cannot undo when the index holds one anywhere. Why: The first refusal hides the rest: a staged edit can come before a submodule or a skip-worktree entry, and only a look at every entry tells a change a reset undoes from a state it does not.

In TS you’d write (pseudocode):

function dirtySource(args: { gitDir: string; commonDir: string; why: CleanRefusal }): DirtySource; // throws a CleanRefusal