Function rustc_mir::const_eval::fn_queries::is_const_fn_raw

pub(in const_eval::fn_queries) fn is_const_fn_raw(
    tcx: TyCtxt<'_>, 
    def_id: DefId
) -> bool

Checks whether the function has a const modifier or, in case it is an intrinsic, whether said intrinsic has a rustc_const_{un,}stable attribute.