Function build_custom_mir

pub(super) fn build_custom_mir<'tcx>(
    tcx: TyCtxt<'tcx>,
    did: DefId,
    hir_id: HirId,
    thir: &Thir<'tcx>,
    expr: ExprId,
    params: &IndexSlice<ParamId, Param<'tcx>>,
    return_ty: Ty<'tcx>,
    return_ty_span: Span,
    span: Span,
    attr: &Attribute,
) -> Body<'tcx>