fn matched_from_ident<'ctx, 'interp, 'rslt>(
    dcx: DiagCtxtHandle<'ctx>,
    ident: Ident,
    interp: &'interp FxHashMap<MacroRulesNormalizedIdent, NamedMatch>,
) -> PResult<'ctx, &'rslt NamedMatch>where
    'interp: 'rslt,Expand description
Returns a NamedMatch item declared on the LHS given an arbitrary Ident