Function insert_niche_check

fn insert_niche_check<'tcx>(
    tcx: TyCtxt<'tcx>,
    local_decls: &mut IndexVec<Local, LocalDecl<'tcx>>,
    block_data: &mut BasicBlockData<'tcx>,
    source_op: Operand<'tcx>,
    valid_range: WrappingRange,
    discr: TyAndSize<'tcx>,
    op_size: Size,
    offset: Size,
    source_info: SourceInfo,
    new_block: BasicBlock,
)