globset: add opt-in Arbitrary trait implementations

This feature is mandatory when using `Glob` in fuzz testing.

Closes #2720

crates/globset/src/glob.rs

@@ -72,6 +72,7 @@ impl MatchStrategy {
 /// It cannot be used directly to match file paths, but it can be converted
 /// to a regular expression string or a matcher.
 #[derive(Clone, Debug, Eq)]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Glob {
     glob: String,
     re: String,
@@ -194,6 +195,7 @@ pub struct GlobBuilder<'a> {
 }
 
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 struct GlobOptions {
     /// Whether to match case insensitively.
     case_insensitive: bool,
@@ -220,6 +222,7 @@ impl GlobOptions {
 }
 
 #[derive(Clone, Debug, Default, Eq, PartialEq)]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 struct Tokens(Vec<Token>);
 
 impl std::ops::Deref for Tokens {
@@ -236,6 +239,7 @@ impl std::ops::DerefMut for Tokens {
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 enum Token {
     Literal(char),
     Any,

crates/globset/src/lib.rs

@@ -94,6 +94,19 @@ Standard Unix-style glob syntax is supported:
 
 A `GlobBuilder` can be used to prevent wildcards from matching path separators,
 or to enable case insensitive matching.
+
+# Crate Features
+
+This crate includes optional features that can be enabled if necessary.
+These features are not required but may be useful depending on the use case.
+
+The following features are available:
+
+* **arbitrary** -
+  Enabling this feature introduces a public dependency on the
+  [`arbitrary`](https://crates.io/crates/arbitrary)
+  crate. Namely, it implements the `Arbitrary` trait from that crate for the
+  [`Glob`] type. This feature is disabled by default.
 */
 
 #![deny(missing_docs)]