Use None eras for era-less calendars (ISO, Chinese, Dangi)

Author: Manishearth

src/builtins/core/calendar.rs

@@ -207,7 +207,7 @@ impl Calendar {
         let calendar_date = self
             .0
             .from_codes(
-                Some(resolved_fields.era_year.era.0.as_str()),
+                resolved_fields.era_year.era.as_ref().map(|e| e.0.as_str()),
                 resolved_fields.era_year.year,
                 IcuMonthCode(resolved_fields.month_code.0),
                 resolved_fields.day,
@@ -272,7 +272,7 @@ impl Calendar {
         let calendar_date = self
             .0
             .from_codes(
-                Some(resolved_fields.era_year.era.0.as_str()),
+                resolved_fields.era_year.era.as_ref().map(|e| e.0.as_str()),
                 resolved_fields.era_year.year,
                 IcuMonthCode(resolved_fields.month_code.0),
                 resolved_fields.day,
@@ -571,9 +571,9 @@ impl Calendar {
     pub(crate) fn get_calendar_default_era(&self) -> Option<EraInfo> {
         match self.0 .0.kind() {
             AnyCalendarKind::Buddhist => Some(era::BUDDHIST_ERA),
-            AnyCalendarKind::Chinese => Some(era::CHINESE_ERA),
+            AnyCalendarKind::Chinese => None,
             AnyCalendarKind::Coptic => Some(era::COPTIC_ERA),
-            AnyCalendarKind::Dangi => Some(era::DANGI_ERA),
+            AnyCalendarKind::Dangi => None,
             AnyCalendarKind::Ethiopian => Some(era::ETHIOPIC_ERA),
             AnyCalendarKind::EthiopianAmeteAlem => Some(era::ETHIOAA_ERA),
             AnyCalendarKind::Gregorian => Some(era::GREGORY_ERA),
@@ -583,7 +583,7 @@ impl Calendar {
             AnyCalendarKind::HijriTabularTypeIIFriday => Some(era::ISLAMIC_ERA),
             AnyCalendarKind::HijriTabularTypeIIThursday => Some(era::ISLAMIC_ERA),
             AnyCalendarKind::HijriUmmAlQura => Some(era::ISLAMIC_ERA),
-            AnyCalendarKind::Iso => Some(era::ISO_ERA),
+            AnyCalendarKind::Iso => None,
             AnyCalendarKind::Japanese => Some(era::JAPANESE_ERA),
             AnyCalendarKind::Persian => Some(era::PERSIAN_ERA),
             AnyCalendarKind::Roc => Some(era::ROC_ERA),

src/builtins/core/calendar/era.rs

@@ -83,12 +83,6 @@ pub(crate) const JAPANESE_INVERSE_ERA_IDENTIFIERS: [TinyAsciiStr<19>; 2] =
 
 // NOTE: The below currently might not align 100% with ICU4X.
 // TODO: Update to align with ICU4X depending on any Era updates.
-
-// Calendars without eras
-pub(crate) const ISO_ERA: EraInfo = valid_era!("default", i32::MIN..=i32::MAX);
-pub(crate) const CHINESE_ERA: EraInfo = valid_era!("chinese", i32::MIN..=i32::MAX);
-pub(crate) const DANGI_ERA: EraInfo = valid_era!("dangi", i32::MIN..=i32::MAX);
-
 pub(crate) const BUDDHIST_ERA: EraInfo = valid_era!("be", i32::MIN..=i32::MAX);
 pub(crate) const COPTIC_ERA: EraInfo = valid_era!("am", 1..=i32::MAX);
 pub(crate) const ETHIOPIC_ERA: EraInfo = valid_era!("am", 1..=i32::MAX);

src/builtins/core/calendar/types.rs

@@ -11,8 +11,6 @@ use crate::{TemporalError, TemporalResult};
 
 use crate::builtins::core::{calendar::Calendar, PartialDate};
 
-use super::era::ISO_ERA;
-
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum ResolutionType {
     Date,
@@ -82,7 +80,7 @@ pub struct Era(pub(crate) TinyAsciiStr<16>);
 
 #[derive(Debug)]
 pub struct EraYear {
-    pub(crate) era: Era,
+    pub(crate) era: Option<Era>,
     pub(crate) year: i32,
 }
 
@@ -114,21 +112,18 @@ impl EraYear {
                 }
                 Ok(Self {
                     year: era_year,
-                    era: Era(era_info.name),
-                })
-            }
-            (Some(year), None, None) => {
-                let Some(era) = partial.calendar.get_calendar_default_era() else {
-                    return Err(TemporalError::r#type()
-                        .with_message("Era is required for the provided calendar."));
-                };
-                Ok(Self {
-                    era: Era(era.name),
-                    year,
+                    era: Some(Era(era_info.name)),
                 })
             }
+            (Some(year), None, None) => Ok(Self {
+                era: partial
+                    .calendar
+                    .get_calendar_default_era()
+                    .map(|e| Era(e.name)),
+                year,
+            }),
             (None, None, None) if resolution_type == ResolutionType::MonthDay => Ok(Self {
-                era: Era(ISO_ERA.name),
+                era: None,
                 year: 1972,
             }),
             _ => Err(TemporalError::r#type()
@@ -494,7 +489,8 @@ mod tests {
                         .expect(&expect_str);
 
                 assert_eq!(
-                    &*era_year.era.0, &*era.name,
+                    &*era_year.era.expect("only testing calendars with era").0,
+                    &*era.name,
                     "Backcalculated era must match"
                 );
                 assert_eq!(era_year.year, 1, "Backcalculated era must match");