Function preprocess_with_source_tracker 

pub fn preprocess_with_source_tracker<P, S, T>(
    entry_point: P,
    search_paths: SearchPaths,
    output_sink: S,
    source_tracker: T,
) -> Result<S, Error>
where
    P: AsRef<Path>,
    S: OutputSink,
    T: SourceTracker,

Processes the entry_point file, potentially inlining files referenced by #include directives and notifying the source_tracker of included files.

Behaves exactly like preprocess, except in that it takes an additional source_tracker argument. The source_tracker will be notified once for each file that is included.

See also the SourceTracker trait and the Source Tracking section of the top-level-documentation.