+fn captures_all_lifetimes(inputs: &[Ty<'_>], output_lifetimes: &[LifetimeName]) -> bool {
+ let input_lifetimes: Vec<LifetimeName> = inputs
+ .iter()
+ .filter_map(|ty| {
+ if let TyKind::Rptr(lt, _) = ty.kind {
+ Some(lt.name)
+ } else {
+ None
+ }
+ })
+ .collect();
+
+ // The lint should trigger in one of these cases:
+ // - There are no input lifetimes
+ // - There's only one output lifetime bound using `+ '_`
+ // - All input lifetimes are explicitly bound to the output
+ input_lifetimes.is_empty()
+ || (output_lifetimes.len() == 1 && matches!(output_lifetimes[0], LifetimeName::Underscore))
+ || input_lifetimes
+ .iter()
+ .all(|in_lt| output_lifetimes.iter().any(|out_lt| in_lt == out_lt))
+}
+