fix clippy warnings

exercises/practice/doubly-linked-list/tests/doubly-linked-list.rs

@@ -259,7 +259,7 @@ fn drop_no_double_frees() {
     use std::cell::Cell;
     struct DropCounter<'a>(&'a Cell<usize>);
 
-    impl<'a> Drop for DropCounter<'a> {
+    impl Drop for DropCounter<'_> {
         fn drop(&mut self) {
             let num = self.0.get();
             self.0.set(num + 1);

exercises/practice/grep/tests/grep.rs

@@ -483,7 +483,7 @@ impl<'a> Files<'a> {
     }
 }
 
-impl<'a> Drop for Files<'a> {
+impl Drop for Files<'_> {
     fn drop(&mut self) {
         for file_name in self.file_names {
             std::fs::remove_file(file_name)

exercises/practice/luhn-from/src/lib.rs

@@ -8,11 +8,11 @@ impl Luhn {
 
 /// Here is the example of how the From trait could be implemented
 /// for the &str type. Naturally, you can implement this trait
-/// by hand for the every other type presented in the test suite,
+/// by hand for every other type presented in the test suite,
 /// but your solution will fail if a new type is presented.
 /// Perhaps there exists a better solution for this problem?
-impl<'a> From<&'a str> for Luhn {
-    fn from(input: &'a str) -> Self {
+impl From<&str> for Luhn {
+    fn from(input: &str) -> Self {
         todo!("From the given input '{input}' create a new Luhn struct.");
     }
 }

exercises/practice/luhn-trait/.meta/example.rs

@@ -20,7 +20,7 @@ impl Luhn for String {
     }
 }
 
-impl<'a> Luhn for &'a str {
+impl Luhn for &str {
     fn valid_luhn(&self) -> bool {
         String::from(*self).valid_luhn()
     }

exercises/practice/luhn-trait/src/lib.rs

@@ -4,10 +4,10 @@ pub trait Luhn {
 
 /// Here is the example of how to implement custom Luhn trait
 /// for the &str type. Naturally, you can implement this trait
-/// by hand for the every other type presented in the test suite,
+/// by hand for every other type presented in the test suite,
 /// but your solution will fail if a new type is presented.
 /// Perhaps there exists a better solution for this problem?
-impl<'a> Luhn for &'a str {
+impl Luhn for &str {
     fn valid_luhn(&self) -> bool {
         todo!("Determine if '{self}' is a valid credit card number.");
     }

exercises/practice/matching-brackets/.meta/example.rs

@@ -9,7 +9,7 @@ struct Brackets {
     pairs: MatchingBrackets,
 }
 
-impl<'a> From<&'a str> for Brackets {
+impl From<&str> for Brackets {
     fn from(i: &str) -> Self {
         Brackets::new(i, None)
     }

exercises/practice/poker/.meta/example.rs

@@ -51,7 +51,7 @@ impl fmt::Display for Suit {
     }
 }
 
-impl<'a> TryFrom<&'a str> for Suit {
+impl TryFrom<&str> for Suit {
     type Error = &'static str;
 
     fn try_from(source: &str) -> Result<Self, Self::Error> {
@@ -115,7 +115,7 @@ impl PartialOrd for Rank {
     }
 }
 
-impl<'a> TryFrom<&'a str> for Rank {
+impl TryFrom<&str> for Rank {
     type Error = &'static str;
 
     fn try_from(source: &str) -> Result<Self, Self::Error> {
@@ -160,7 +160,7 @@ impl fmt::Display for Card {
     }
 }
 
-impl<'a> TryFrom<&'a str> for Card {
+impl TryFrom<&str> for Card {
     type Error = &'static str;
 
     fn try_from(source: &str) -> Result<Self, Self::Error> {
@@ -262,7 +262,7 @@ struct Hand<'a> {
     hand_type: PokerHand,
 }
 
-impl<'a> Hand<'a> {
+impl Hand<'_> {
     fn cmp_high_card(&self, other: &Hand, card: usize) -> Ordering {
         let mut ordering = self.cards[card]
             .rank
@@ -312,13 +312,13 @@ impl<'a> Hand<'a> {
     }
 }
 
-impl<'a> fmt::Display for Hand<'a> {
+impl fmt::Display for Hand<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{}", self.source)
     }
 }
 
-impl<'a> PartialOrd for Hand<'a> {
+impl PartialOrd for Hand<'_> {
     fn partial_cmp(&self, other: &Hand) -> Option<Ordering> {
         Some(self.hand_type.cmp(&other.hand_type).then_with(|| {
             use crate::PokerHand::*;

exercises/practice/react/.meta/example.rs

@@ -249,7 +249,7 @@ impl<'a, T: Copy + PartialEq> Reactor<'a, T> {
     }
 }
 
-impl<'a, T: Copy + PartialEq> Default for Reactor<'a, T> {
+impl<T: Copy + PartialEq> Default for Reactor<'_, T> {
     fn default() -> Self {
         Self::new()
     }

exercises/practice/rectangles/.meta/example.rs

@@ -70,7 +70,7 @@ impl Area for RealArea {
 struct TransposedArea<'a>(&'a RealArea);
 
 // For vertical scanning
-impl<'a> Area for TransposedArea<'a> {
+impl Area for TransposedArea<'_> {
     #[allow(clippy::misnamed_getters)]
     fn width(&self) -> usize {
         self.0.height

exercises/practice/xorcism/.meta/example.rs

@@ -110,7 +110,7 @@ where
     }
 }
 
-impl<'a, W> Write for Writer<'a, W>
+impl<W> Write for Writer<'_, W>
 where
     W: Write,
 {
@@ -149,7 +149,7 @@ where
     }
 }
 
-impl<'a, R> Read for Reader<'a, R>
+impl<R> Read for Reader<'_, R>
 where
     R: Read,
 {