fn branches<'tcx>(
ecx: &CompileTimeInterpCx<'tcx>,
place: &MPlaceTy<'tcx>,
field_count: usize,
variant: Option<VariantIdx>,
num_nodes: &mut usize,
visited: &mut FxHashSet<MPlaceTy<'tcx>>,
settled: &mut FxHashMap<MPlaceTy<'tcx>, EvalToValTreeResult<'tcx>>,
) -> EvalToValTreeResult<'tcx>