refactor: Derive Default for enums

As of Rust 1.62, enums can use `#[derive(Default)]`.

See <rust-lang/rust#94457>.

fluent-bundle/examples/custom_type.rs

@@ -21,21 +21,16 @@ use fluent_bundle::{FluentArgs, FluentBundle, FluentResource, FluentValue};
 //  - timeStyle
 //
 // with an enum of allowed values.
-#[derive(Debug, PartialEq, Eq, Clone, Hash)]
+#[derive(Debug, Default, PartialEq, Eq, Clone, Hash)]
 enum DateTimeStyleValue {
     Full,
     Long,
     Medium,
     Short,
+    #[default]
     None,
 }
 
-impl std::default::Default for DateTimeStyleValue {
-    fn default() -> Self {
-        Self::None
-    }
-}
-
 // This is just a helper to make it easier to convert
 // a value provided to FluentArgs into an option value.
 impl<'l> From<&FluentValue<'l>> for DateTimeStyleValue {

fluent-bundle/src/types/number.rs

@@ -8,19 +8,14 @@ use intl_pluralrules::operands::PluralOperands;
 use crate::args::FluentArgs;
 use crate::types::FluentValue;
 
-#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, Default, Hash, PartialEq, Eq)]
 pub enum FluentNumberStyle {
+    #[default]
     Decimal,
     Currency,
     Percent,
 }
 
-impl std::default::Default for FluentNumberStyle {
-    fn default() -> Self {
-        Self::Decimal
-    }
-}
-
 impl From<&str> for FluentNumberStyle {
     fn from(input: &str) -> Self {
         match input {
@@ -32,19 +27,14 @@ impl From<&str> for FluentNumberStyle {
     }
 }
 
-#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, Default, Hash, PartialEq, Eq)]
 pub enum FluentNumberCurrencyDisplayStyle {
+    #[default]
     Symbol,
     Code,
     Name,
 }
 
-impl std::default::Default for FluentNumberCurrencyDisplayStyle {
-    fn default() -> Self {
-        Self::Symbol
-    }
-}
-
 impl From<&str> for FluentNumberCurrencyDisplayStyle {
     fn from(input: &str) -> Self {
         match input {

fluent-bundle/tests/custom_types.rs

@@ -47,21 +47,16 @@ fn fluent_custom_type() {
 
 #[test]
 fn fluent_date_time_builtin() {
-    #[derive(Debug, PartialEq, Clone)]
+    #[derive(Debug, Default, PartialEq, Clone)]
     enum DateTimeStyleValue {
         Full,
         Long,
         Medium,
         Short,
+        #[default]
         None,
     }
 
-    impl std::default::Default for DateTimeStyleValue {
-        fn default() -> Self {
-            Self::None
-        }
-    }
-
     impl<'l> From<&FluentValue<'l>> for DateTimeStyleValue {
         fn from(input: &FluentValue) -> Self {
             if let FluentValue::String(s) = input {