Function rustc_trait_selection::traits::coherence::overlapping_impls

pub fn overlapping_impls<'tcx>(
    tcx: TyCtxt<'tcx>,
    impl1_def_id: DefId,
    impl2_def_id: DefId,
    skip_leak_check: SkipLeakCheck,
    overlap_mode: OverlapMode
) -> Option<OverlapResult<'tcx>>

If there are types that satisfy both impls, returns Some with a suitably-freshened ImplHeader with those types substituted. Otherwise, returns None.