Fix misc clippy warnings

Why does it want me to use bytecount? It's not even faster

2020/src/day11.rs

@@ -1,6 +1,8 @@
 use std::io::Read;
 use std::mem::swap;
 
+use bytecount::naive_count_32;
+
 use crate::common::read_char_grid;
 use crate::Solution;
 
@@ -9,12 +11,12 @@ fn neighbours(grid: &[Vec<u8>], r: usize, c: usize) -> usize {
 
     if r > 0 {
         let range = c.saturating_sub(1)..grid[r - 1].len().min(c + 2);
-        n += grid[r - 1][range].iter().filter(|&&s| s == b'#').count();
+        n += naive_count_32(&grid[r - 1][range], b'#');
     }
 
     if r < grid.len() - 1 {
         let range = c.saturating_sub(1)..grid[r + 1].len().min(c + 2);
-        n += grid[r + 1][range].iter().filter(|&&s| s == b'#').count();
+        n += naive_count_32(&grid[r + 1][range], b'#');
     }
 
     if c > 0 && grid[r][c - 1] == b'#' {

2020/src/day14.rs

@@ -65,7 +65,7 @@ fn x_mask_permutations(mut x_mask: u64, permutations: &mut Vec<u64>) {
     while x_mask > 0 {
         let trailing = x_mask.trailing_zeros();
 
-        let bit = 1 << trailing + offset;
+        let bit = 1 << (trailing + offset);
 
         x_mask >>= trailing + 1;
         offset += trailing + 1;

2020/src/day16.rs

@@ -15,6 +15,8 @@ fn split_nums<'a>(s: &'a str) -> impl Iterator<Item = u32> + 'a {
     })
 }
 
+// Clippy allow here because this type is used exactly once
+#[allow(clippy::type_complexity)]
 fn read_input(input: &mut dyn Read) -> (HashMap<String, Vec<RangeInclusive<u32>>>, Vec<Vec<u32>>) {
     let mut lines = Lines::new(input).filter(|s| !s.is_empty());