must_use

src/position.rs

@@ -54,6 +54,7 @@ use std::iter::FusedIterator;
 /// The order on [`Position`] is defined only for use in data structures. Hence its only
 /// requirement is to be efficient while respecting the [`Ord`] trait protocol. It should not be
 /// considered stable.
+#[must_use]
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Position(Setup);
 
@@ -91,6 +92,7 @@ impl Position {
     /// position.legal_moves().len()
     /// # };
     /// ```
+    #[must_use]
     #[inline]
     pub fn count_legal_moves(&self) -> usize {
         struct MoveGenImpl {