deps: bump to memchr 2.6

This bumps the minimum memchr version to 2.6, which brings in
massive improvements to aarch64 for single substring search. We also can
now enable the new `alloc` feature in `memchr` when `alloc` is enable
for `regex` and `regex-automata`.

We also squash some warnings.

[1]: BurntSushi/memchr#129

Author: BurntSushi

Cargo.toml

@@ -168,7 +168,7 @@ optional = true
 
 # For skipping along search text quickly when a leading byte is known.
 [dependencies.memchr]
-version = "2.5.0"
+version = "2.6.0"
 optional = true
 
 # For the actual regex engines.

fuzz/fuzz_targets/ast_fuzz_match.rs

@@ -25,11 +25,12 @@ fuzz_target!(|data: FuzzData| -> Corpus {
     let _ = env_logger::try_init();
 
     let pattern = format!("{}", data.ast);
-    let Ok(re) = RegexBuilder::new(&pattern).size_limit(1<<20).build() else {
+    let Ok(re) = RegexBuilder::new(&pattern).size_limit(1 << 20).build()
+    else {
         return Corpus::Reject;
     };
-    re.is_match(&data.haystack);
-    re.find(&data.haystack);
-    re.captures(&data.haystack).map_or(0, |c| c.len());
+    let _ = re.is_match(&data.haystack);
+    let _ = re.find(&data.haystack);
+    let _ = re.captures(&data.haystack).map_or(0, |c| c.len());
     Corpus::Keep
 });

fuzz/fuzz_targets/ast_fuzz_match_bytes.rs

@@ -25,11 +25,12 @@ fuzz_target!(|data: FuzzData| -> Corpus {
     let _ = env_logger::try_init();
 
     let pattern = format!("{}", data.ast);
-    let Ok(re) = RegexBuilder::new(&pattern).size_limit(1<<20).build() else {
+    let Ok(re) = RegexBuilder::new(&pattern).size_limit(1 << 20).build()
+    else {
         return Corpus::Reject;
     };
-    re.is_match(&data.haystack);
-    re.find(&data.haystack);
-    re.captures(&data.haystack).map_or(0, |c| c.len());
+    let _ = re.is_match(&data.haystack);
+    let _ = re.find(&data.haystack);
+    let _ = re.captures(&data.haystack).map_or(0, |c| c.len());
     Corpus::Keep
 });

regex-automata/Cargo.toml

@@ -84,7 +84,7 @@ internal-instrument-pikevm = ["logging", "std"]
 [dependencies]
 aho-corasick = { version = "1.0.0", optional = true, default-features = false }
 log = { version = "0.4.14", optional = true }
-memchr = { version = "2.5.0", optional = true, default-features = false }
+memchr = { version = "2.6.0", optional = true, default-features = false }
 regex-syntax = { path = "../regex-syntax", version = "0.7.4", optional = true, default-features = false }
 
 [dev-dependencies]