Board::game_winner: remove unneeded argument

src/board.rs

@@ -324,10 +324,11 @@ impl Board {
     }
 
     /// Returns the winner of the board (if any)
-    pub fn game_winner(&self, turn: Piece) -> Winner {
+    pub fn game_winner(&self) -> Winner {
         // Wikipedia: `Players take alternate turns. If one player cannot make a valid move, play passes back to the other player. The game ends when the grid has filled up or if neither player can make a valid move.`
 
-        if self.possible_moves(turn).next().is_some() || self.possible_moves(!turn).next().is_some()
+        if self.possible_moves(Piece::Black).next().is_some()
+            || self.possible_moves(Piece::White).next().is_some()
         {
             // player can still make a move, there is no winner
             return Winner::None;

src/future_moves.rs

@@ -170,7 +170,7 @@ impl FutureMoves {
                     i,
                     j,
                     board: new_board,
-                    winner: new_board.game_winner(new_color),
+                    winner: new_board.game_winner(),
                     parent: Some(parent_idx),
                     children: Vec::new(),
                     value: 0,
@@ -295,7 +295,7 @@ impl FutureMoves {
             i: 0,
             j: 0,
             board,
-            winner: Winner::None,
+            winner: board.game_winner(),
             parent: None,
             children: Vec::new(),
             value: 0,

src/game.rs

@@ -97,7 +97,7 @@ impl Game {
 
             println!("{}", self);
 
-            match self.board.game_winner(self.players[current_player].color()) {
+            match self.board.game_winner() {
                 Winner::Player(piece) => {
                     println!("{} Wins!", piece.text());
                     break;