Function compute_concrete_types_from_defining_uses 

fn compute_concrete_types_from_defining_uses<'tcx>(
    rcx: &RegionCtxt<'_, 'tcx>,
    concrete_opaque_types: &mut ConcreteOpaqueTypes<'tcx>,
    defining_uses: &[DefiningUse<'tcx>],
    errors: &mut Vec<DeferredOpaqueTypeError<'tcx>>,
)