all: fix clippy lints for rust 1.65

aoc2020/src/day11.rs

@@ -111,9 +111,8 @@ impl Layout {
             count += self
                 .grid
                 .get(i)
-                .map(|line| line.get(j))
-                .flatten()
-                .map(|&cell| if cell == value { 1 } else { 0 })
+                .and_then(|line| line.get(j))
+                .map(|&cell| u8::from(cell == value))
                 .unwrap_or(0);
         }
 
@@ -131,7 +130,7 @@ impl Layout {
 
                 let (i, j) = (i.wrapping_add(di as usize), j.wrapping_add(dj as usize));
 
-                let cell = self.grid.get(i).map(|line| line.get(j)).flatten();
+                let cell = self.grid.get(i).and_then(|line| line.get(j));
 
                 match cell {
                     // keep going, the next seat is farther away

aoc2020/src/day16.rs

@@ -22,8 +22,7 @@ fn part1(input: &str) -> Result<u64> {
 
     Ok(tickets
         .iter()
-        .map(|t| t.invalid_values(&fields_vec))
-        .flatten()
+        .flat_map(|t| t.invalid_values(&fields_vec))
         .sum())
 }
 
@@ -224,7 +223,7 @@ mod tests {
 
         let matches = assign_field_positions(fields, tickets);
 
-        let expected = (&["row", "class", "seat"])
+        let expected = ["row", "class", "seat"]
             .iter()
             .copied()
             .enumerate()

aoc2020/src/day18.rs

@@ -113,7 +113,7 @@ fn mul(input: &str) -> IResult<&str, Expr> {
 }
 
 fn num(input: &str) -> IResult<&str, Expr> {
-    map_res(take_while1(|c: char| c.is_digit(10)), |res: &str| {
+    map_res(take_while1(|c: char| c.is_ascii_digit()), |res: &str| {
         res.parse().map(Expr::Num)
     })(input)
 }