Function module_tree_relpath 

pub fn module_tree_relpath(
    module: &AIRModule,
    source_path: &Path,
    target: &TargetProfile,
) -> PathBuf

Map a module’s declared dotted path (core.option) to its relative output path in a per-module tree, with the target’s file extension (core/option.<ext>). The entry module is laid out separately (always main.<ext> at a stable location), so callers pass non-entry modules here; a module with no declared path falls back to its source-mirrored path.