Function walk_modules_with_path 

pub fn walk_modules_with_path<'a>(
    roots: &'a [Module],
) -> impl Iterator<Item = (&'a Module, String)>

Like walk_modules, but each module is paired with its underscore-joined path (e.g. parent_child_grandchild). The path matches the canonical C symbol prefix segment that the C generator builds when emitting {c_prefix}_{module_path}_{name}.