style: simplify string formatting for readability

src/tests.rs

@@ -1561,7 +1561,7 @@ fn regression_case_insensitive_prefilter() {
         for c2 in b'a'..b'z' {
             let c = c as char;
             let c2 = c2 as char;
-            let needle = format!("{}{}", c, c2).to_lowercase();
+            let needle = format!("{c}{c2}").to_lowercase();
             let haystack = needle.to_uppercase();
             let ac = AhoCorasick::builder()
                 .ascii_case_insensitive(true)
@@ -1571,10 +1571,7 @@ fn regression_case_insensitive_prefilter() {
             assert_eq!(
                 1,
                 ac.find_iter(&haystack).count(),
-                "failed to find {:?} in {:?}\n\nautomaton:\n{:?}",
-                needle,
-                haystack,
-                ac,
+                "failed to find {needle:?} in {haystack:?}\n\nautomaton:\n{ac:?}",
             );
         }
     }

src/util/alphabet.rs

@@ -105,12 +105,12 @@ impl core::fmt::Debug for ByteClasses {
                 if i > 0 {
                     write!(f, ", ")?;
                 }
-                write!(f, "{:?} => [", class)?;
+                write!(f, "{class:?} => [")?;
                 for (start, end) in self.element_ranges(class) {
                     if start == end {
-                        write!(f, "{:?}", start)?;
+                        write!(f, "{start:?}")?;
                     } else {
-                        write!(f, "{:?}-{:?}", start, end)?;
+                        write!(f, "{start:?}-{end:?}")?;
                     }
                 }
                 write!(f, "]")?;

src/util/error.rs

@@ -83,16 +83,14 @@ impl core::fmt::Display for BuildError {
                 write!(
                     f,
                     "state identifier overflow: failed to create state ID \
-                     from {}, which exceeds the max of {}",
-                    requested_max, max,
+                     from {requested_max}, which exceeds the max of {max}",
                 )
             }
             ErrorKind::PatternIDOverflow { max, requested_max } => {
                 write!(
                     f,
                     "pattern identifier overflow: failed to create pattern ID \
-                     from {}, which exceeds the max of {}",
-                    requested_max, max,
+                     from {requested_max}, which exceeds the max of {max}",
                 )
             }
             ErrorKind::PatternTooLong { pattern, len } => {
@@ -236,15 +234,13 @@ impl core::fmt::Display for MatchError {
             MatchErrorKind::UnsupportedStream { got } => {
                 write!(
                     f,
-                    "match kind {:?} does not support stream searching",
-                    got,
+                    "match kind {got:?} does not support stream searching",
                 )
             }
             MatchErrorKind::UnsupportedOverlapping { got } => {
                 write!(
                     f,
-                    "match kind {:?} does not support overlapping searches",
-                    got,
+                    "match kind {got:?} does not support overlapping searches",
                 )
             }
             MatchErrorKind::UnsupportedEmpty => {