Make ZoneVariant a closed, non-exhaustive enum (#5760)

#5745

components/datetime/benches/datetime.rs

@@ -40,7 +40,7 @@ fn datetime_benches(c: &mut Criterion) {
                                             Date::try_new_iso(2024, 1, 1).unwrap(),
                                             Time::midnight(),
                                         ))
-                                        .with_zone_variant(ZoneVariant::standard()),
+                                        .with_zone_variant(ZoneVariant::Standard),
                                 }
                             }
                         })

components/datetime/src/fieldset.rs

@@ -568,7 +568,7 @@ macro_rules! impl_zone_marker {
             /// let zone = TimeZoneBcp47Id(tinystr!(8, "uschi"))
             ///     .with_offset("-05".parse().ok())
             ///     .at_time((Date::try_new_iso(2022, 8, 29).unwrap(), Time::midnight()))
-            ///     .with_zone_variant(ZoneVariant::daylight());
+            ///     .with_zone_variant(ZoneVariant::Daylight);
             ///
             /// assert_try_writeable_eq!(
             ///     fmt.convert_and_format(&zone),
@@ -598,7 +598,7 @@ macro_rules! impl_zone_marker {
             /// let zone = TimeZoneBcp47Id(tinystr!(8, "uschi"))
             ///     .with_offset("-05".parse().ok())
             ///     .at_time((Date::try_new_iso(2022, 8, 29).unwrap(), Time::midnight()))
-            ///     .with_zone_variant(ZoneVariant::daylight());
+            ///     .with_zone_variant(ZoneVariant::Daylight);
             ///
             /// assert_try_writeable_eq!(
             ///     fmt.format(&zone),
@@ -995,7 +995,7 @@ impl_zone_marker!(
     /// let zone = TimeZoneBcp47Id(tinystr!(8, "brsao"))
     ///     .with_offset("-03".parse().ok())
     ///     .at_time((Date::try_new_iso(2022, 1, 29).unwrap(), Time::midnight()))
-    ///     .with_zone_variant(ZoneVariant::standard());
+    ///     .with_zone_variant(ZoneVariant::Standard);
     ///
     /// assert_try_writeable_eq!(
     ///     fmt.format(&zone),
@@ -1155,7 +1155,7 @@ impl_zone_marker!(
     /// let time = Time::midnight();
     /// let time_zone_at_time = time_zone_basic.at_time((date, time));
     ///
-    /// let time_zone_full = time_zone_at_time.with_zone_variant(ZoneVariant::standard());
+    /// let time_zone_full = time_zone_at_time.with_zone_variant(ZoneVariant::Standard);
     ///
     /// let formatter = FixedCalendarDateTimeFormatter::<(), _>::try_new(
     ///     &locale!("en-US").into(),
@@ -1214,7 +1214,7 @@ impl_zone_marker!(
     /// let zone = TimeZoneBcp47Id(tinystr!(8, "brsao"))
     ///     .with_offset("-03".parse().ok())
     ///     .at_time((Date::try_new_iso(2022, 1, 29).unwrap(), Time::midnight()))
-    ///     .with_zone_variant(ZoneVariant::standard());
+    ///     .with_zone_variant(ZoneVariant::Standard);
     ///
     /// assert_try_writeable_eq!(
     ///     fmt.format(&zone),

components/datetime/src/time_zone.rs

@@ -622,12 +622,11 @@ impl FormatTimeZone for SpecificLocationFormat {
             return Ok(Err(FormatTimeZoneError::Fallback));
         };
 
-        if zone_variant == ZoneVariant::daylight() {
-            &locations.pattern_daylight
-        } else if zone_variant == ZoneVariant::standard() {
-            &locations.pattern_standard
-        } else {
-            &locations.pattern_generic
+        match zone_variant {
+            ZoneVariant::Standard => &locations.pattern_standard,
+            ZoneVariant::Daylight => &locations.pattern_daylight,
+            // Compiles out due to tilde dependency on `icu_timezone`
+            _ => unreachable!(),
         }
         .interpolate([location])
         .write_to(sink)?;

components/datetime/tests/mock.rs

@@ -67,7 +67,7 @@ pub fn parse_zoned_gregorian_from_str(
                         date: zdt.date,
                         time: zdt.time,
                         // For fixture tests, set the zone variant to standard here
-                        zone: zdt.zone.with_zone_variant(ZoneVariant::standard()),
+                        zone: zdt.zone.with_zone_variant(ZoneVariant::Standard),
                     }
                 }
                 Err(e) => panic!("could not parse input: {input}: {e:?}"),

components/timezone/src/ixdtf.rs

@@ -369,17 +369,17 @@ impl<'a> Intermediate<'a> {
         {
             Some(ZoneOffsets { standard, daylight }) => {
                 if offset == standard {
-                    ZoneVariant::standard()
+                    ZoneVariant::Standard
                 } else if Some(offset) == daylight {
-                    ZoneVariant::daylight()
+                    ZoneVariant::Daylight
                 } else {
                     return Err(ParseError::InvalidOffsetError);
                 }
             }
             None => {
                 // time_zone_id not found; Etc/Unknown?
                 debug_assert_eq!(time_zone_id.0.as_str(), "unk");
-                ZoneVariant::standard()
+                ZoneVariant::Standard
             }
         };
         Ok(time_zone_id
@@ -490,7 +490,7 @@ impl IxdtfParser {
     /// assert_eq!(zoneddatetime.time.nanosecond.number(), 0);
     /// assert_eq!(zoneddatetime.zone.time_zone_id(), TimeZoneBcp47Id(tinystr!(8, "uschi")));
     /// assert_eq!(zoneddatetime.zone.offset(), Some(UtcOffset::try_from_seconds(-18000).unwrap()));
-    /// assert_eq!(zoneddatetime.zone.zone_variant(), ZoneVariant::daylight());
+    /// assert_eq!(zoneddatetime.zone.zone_variant(), ZoneVariant::Daylight);
     /// let (_, _) = zoneddatetime.zone.local_time();
     /// ```
     ///
@@ -633,7 +633,7 @@ impl IxdtfParser {
     /// assert_eq!(zoneddatetime.time.nanosecond.number(), 0);
     /// assert_eq!(zoneddatetime.zone.time_zone_id(), TimeZoneBcp47Id(tinystr!(8, "uschi")));
     /// assert_eq!(zoneddatetime.zone.offset(), Some(UtcOffset::try_from_seconds(-18000).unwrap()));
-    /// assert_eq!(zoneddatetime.zone.zone_variant(), ZoneVariant::daylight());
+    /// assert_eq!(zoneddatetime.zone.zone_variant(), ZoneVariant::Daylight);
     /// let (_, _) = zoneddatetime.zone.local_time();
     /// ```
     ///
@@ -690,7 +690,7 @@ impl IxdtfParser {
     ///
     /// assert_eq!(consistent_tz_from_both.zone.time_zone_id(), TimeZoneBcp47Id(tinystr!(8, "uschi")));
     /// assert_eq!(consistent_tz_from_both.zone.offset(), Some(UtcOffset::try_from_seconds(-18000).unwrap()));
-    /// assert_eq!(consistent_tz_from_both.zone.zone_variant(), ZoneVariant::daylight());
+    /// assert_eq!(consistent_tz_from_both.zone.zone_variant(), ZoneVariant::Daylight);
     /// let (_, _) = consistent_tz_from_both.zone.local_time();
     ///
     /// // We know that America/Los_Angeles never used a -05:00 offset at any time of the year 2024

components/timezone/src/lib.rs

@@ -77,7 +77,7 @@
 //! let time_zone_at_time = time_zone.at_time((Date::try_new_iso(2023, 12, 2).unwrap(), Time::midnight()));
 //!
 //! // Extend to a TimeZoneInfo<Full> by adding a zone variant
-//! let time_zone_with_variant = time_zone_at_time.with_zone_variant(ZoneVariant::standard());
+//! let time_zone_with_variant = time_zone_at_time.with_zone_variant(ZoneVariant::Standard);
 //! ```
 
 // https://github.com/unicode-org/icu4x/blob/main/documents/process/boilerplate.md#library-annotations

components/timezone/src/types.rs

@@ -4,9 +4,6 @@
 
 use crate::error::InvalidOffsetError;
 use core::str::FromStr;
-use tinystr::{tinystr, TinyAsciiStr};
-use zerovec::ule::{AsULE, ULE};
-use zerovec::{ZeroSlice, ZeroVec};
 
 /// An offset from Coordinated Universal Time (UTC)
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Default)]
@@ -182,48 +179,22 @@ impl FromStr for UtcOffset {
 ///
 /// The semantics vary from time zone to time zone and could represent concepts
 /// such as Standard time, Daylight time, Summer time, or Ramadan time.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash, ULE)]
-#[repr(transparent)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
+#[zerovec::make_ule(ZoneVariantULE)]
+#[repr(u8)]
 #[cfg_attr(feature = "datagen", derive(serde::Serialize, databake::Bake))]
 #[cfg_attr(feature = "datagen", databake(path = icu_timezone))]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize))]
-#[allow(clippy::exhaustive_structs)] // newtype
-pub struct ZoneVariant(pub TinyAsciiStr<2>);
-
-impl ZoneVariant {
-    /// Returns the variant corresponding to `"standard"` in CLDR.
+#[non_exhaustive]
+pub enum ZoneVariant {
+    /// The variant corresponding to `"standard"` in CLDR.
     ///
     /// The semantics vary from time zone to time zone. The time zone display
     /// name of this variant may or may not be called "Standard Time".
-    pub const fn standard() -> Self {
-        Self(tinystr!(2, "st"))
-    }
-    /// Returns the variant corresponding to `"daylight"` in CLDR.
+    Standard = 0,
+    /// The variant corresponding to `"daylight"` in CLDR.
     ///
     /// The semantics vary from time zone to time zone. The time zone display
     /// name of this variant may or may not be called "Daylight Time".
-    pub const fn daylight() -> Self {
-        Self(tinystr!(2, "dt"))
-    }
-}
-
-impl AsULE for ZoneVariant {
-    type ULE = Self;
-
-    #[inline]
-    fn to_unaligned(self) -> Self::ULE {
-        self
-    }
-
-    #[inline]
-    fn from_unaligned(unaligned: Self::ULE) -> Self {
-        unaligned
-    }
-}
-
-impl<'a> zerovec::maps::ZeroMapKV<'a> for ZoneVariant {
-    type Container = ZeroVec<'a, ZoneVariant>;
-    type Slice = ZeroSlice<ZoneVariant>;
-    type GetType = ZoneVariant;
-    type OwnedType = ZoneVariant;
+    Daylight = 1,
 }