Fix final clippy warnings

2020/src/common.rs

@@ -93,6 +93,8 @@ where
     T: Read,
 {
     reader: BufReader<T>,
+    // Clippy doesn't understand the use case of an Rc which is immediately released
+    #[allow(clippy::rc_buffer)]
     buffer: Rc<String>,
 }
 

2020/src/day10.rs

@@ -11,7 +11,7 @@ impl Solution for Day10 {
         let mut adapters: Vec<u32> = from_lines(input);
         // Outlet
         adapters.push(0);
-        adapters.sort();
+        adapters.sort_unstable();
         let device = *adapters.last().unwrap() + 3;
         adapters.push(device);
 
@@ -27,7 +27,7 @@ impl Solution for Day10 {
     fn part2(&mut self, input: &mut dyn Read) -> String {
         let mut adapters: Vec<u32> = from_lines(input);
         adapters.push(0);
-        adapters.sort();
+        adapters.sort_unstable();
 
         let mut methods = vec![0u64; adapters.len()];
         methods[0] = 1;

2020/src/day14.rs

@@ -16,12 +16,12 @@ impl FromStr for Entry {
     type Err = Infallible;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        if s.starts_with("mask = ") {
+        if let Some(s) = s.strip_prefix("mask = ") {
             let mut zero_mask = 0;
             let mut one_mask = 0;
             let mut x_mask = 0;
 
-            for c in s[7..].chars() {
+            for c in s.chars() {
                 zero_mask <<= 1;
                 one_mask <<= 1;
                 x_mask <<= 1;