Function rustc_mir_build::thir::pattern::_match::compute_match_usefulness

pub(crate) fn compute_match_usefulness<'p, 'tcx>(
    cx: &MatchCheckCtxt<'p, 'tcx>, 
    arms: &[MatchArm<'p, 'tcx>], 
    scrut_hir_id: HirId, 
    scrut_ty: Ty<'tcx>
) -> UsefulnessReport<'p, 'tcx>

The entrypoint for the usefulness algorithm. Computes whether a match is exhaustive and which of its arms are reachable.

Note: the input patterns must have been lowered through MatchVisitor::lower_pattern.