Function dedup_compound_props 

pub(crate) fn dedup_compound_props<'a, 'tcx>(
    props: impl Iterator<Item = &'a Property<'tcx>>,
) -> Vec<&'a Property<'tcx>>

Drop consecutive duplicate compound-def entries: a def expands to several primitives sharing the same origin name and arguments, which should render as a single name(args) line.