[core] Add #[must_use] to several methods in coordinates

core/src/coordinates.rs

@@ -85,7 +85,6 @@ macro_rules! range_bound_struct {
                 &self.0
             }
 
-            #[must_use]
             $vis fn iter(&self) -> impl Iterator<Item = Self> {
                 (Self::FIRST.0..=Self::LAST.0).map(Self)
             }
@@ -195,10 +194,12 @@ impl Rank {
 
     pub const PAWN_DOUBLE_PUSH_TARGET_RANKS: [Rank; 2] = [Rank::FOUR, Rank::FIVE];
 
+    #[must_use]
     pub fn is_pawn_starting_rank(&self, color: Color) -> bool {
         self == &Self::PAWN_STARTING_RANKS[color as usize]
     }
 
+    #[must_use]
     pub fn is_pawn_double_push_target_rank(&self, color: Color) -> bool {
         self == &Self::PAWN_DOUBLE_PUSH_TARGET_RANKS[color as usize]
     }
@@ -220,12 +221,14 @@ impl Square {
     /// # Safety
     ///
     /// This function does not do any bounds checking on the input.
+    #[must_use]
     pub unsafe fn from_index(x: u8) -> Square {
         debug_assert!((x as usize) < Self::NUM);
         Self::try_from(x).unwrap_unchecked()
     }
 
     #[inline]
+    #[must_use]
     pub fn from_file_rank(file: File, rank: Rank) -> Square {
         let file_int: u8 = file.into();
         let rank_int: u8 = rank.into();