Function rustc_attr::find_const_stability

pub fn find_const_stability(
    sess: &Session,
    attrs: &[Attribute],
    item_sp: Span
) -> Option<(ConstStability, Span)>

Collects stability info from rustc_const_stable/rustc_const_unstable/rustc_promotable attributes in attrs. Returns None if no stability attributes are found.