Remove HijriSimulatedMecca / islamic-rgsa (#597)

The spec doesn't have it anymore.

We use AnyCalendarKind parsing code so we still parse it, we just turn
it into Iso.

I don't quite know the best way to handle this for temporal_rs:
Calendar::new is infallible, but it's mostly internally used in parsing,
and we accept AnyCalendarKinds in our public API.

I think in the long run we should switch to `try_new` and in the IXDTF
parsing case have a fallback to Iso.

Author: Manishearth

src/builtins/core/calendar.rs

@@ -90,8 +90,6 @@ impl Calendar {
     pub const HIJRI_TABULAR_THURSDAY: Self = Self::new(AnyCalendarKind::HijriTabularTypeIIThursday);
     /// The Hijri Umm al-Qura calendar
     pub const HIJRI_UMM_AL_QURA: Self = Self::new(AnyCalendarKind::HijriUmmAlQura);
-    /// The Hijri simulated calendar
-    pub const HIJRI_SIMULATED: Self = Self::new(AnyCalendarKind::HijriSimulatedMecca);
     /// The ISO 8601 calendar
     pub const ISO: Self = Self::new(AnyCalendarKind::Iso);
     /// The Japanese calendar
@@ -135,7 +133,8 @@ impl Calendar {
                 }
             }
             AnyCalendarKind::HijriSimulatedMecca => {
-                const { &AnyCalendar::HijriSimulated(Hijri::new_simulated_mecca()) }
+                // This calendar is currently unsupported by Temporal
+                &AnyCalendar::Iso(Iso)
             }
             AnyCalendarKind::HijriTabularTypeIIThursday => {
                 const {

src/builtins/core/plain_month_day.rs

@@ -528,34 +528,30 @@ mod tests {
 
     #[test]
     /// This test is for calendars where we don't wish to hardcode dates; but we do wish to know
-    /// that monthcodes can be constructed without issue
-    fn automated_reference_year() {
+    /// that monthcodes can be constructed without issue (currently only UAQ)
+    fn automated_uaq_reference_year() {
         let reference_iso = IsoDate::new_unchecked(1972, 12, 31);
-        for cal in [
-            AnyCalendarKind::HijriSimulatedMecca,
-            AnyCalendarKind::HijriUmmAlQura,
-        ] {
-            let calendar = Calendar::new(cal);
-            for month in 1..=12 {
-                for day in [29, 30] {
-                    let month_code = crate::builtins::calendar::month_to_month_code(month).unwrap();
-
-                    let calendar_fields = CalendarFields {
-                        month_code: Some(month_code),
-                        day: Some(day),
-                        ..Default::default()
-                    };
-
-                    let md = calendar
-                        .month_day_from_fields(calendar_fields, Overflow::Reject)
-                        .unwrap();
-
-                    assert!(
-                        md.iso <= reference_iso,
-                        "Reference ISO for {month}-{day} must be before 1972-12-31, found, {:?}",
-                        md.iso,
-                    );
-                }
+
+        let calendar = Calendar::new(AnyCalendarKind::HijriUmmAlQura);
+        for month in 1..=12 {
+            for day in [29, 30] {
+                let month_code = crate::builtins::calendar::month_to_month_code(month).unwrap();
+
+                let calendar_fields = CalendarFields {
+                    month_code: Some(month_code),
+                    day: Some(day),
+                    ..Default::default()
+                };
+
+                let md = calendar
+                    .month_day_from_fields(calendar_fields, Overflow::Reject)
+                    .unwrap();
+
+                assert!(
+                    md.iso <= reference_iso,
+                    "Reference ISO for {month}-{day} must be before 1972-12-31, found, {:?}",
+                    md.iso,
+                );
             }
         }
     }

src/parsed_intermediates.rs

@@ -24,6 +24,9 @@ use ixdtf::records::UtcOffsetRecordOrZ;
 fn extract_kind(calendar: Option<&[u8]>) -> TemporalResult<AnyCalendarKind> {
     Ok(calendar
         .map(Calendar::try_kind_from_utf8)
+        // Note that this will successfully parse AnyCalendarKind::HijriSimulatedMecca
+        // However, Calendar::new will immediately turn it into an ISO calendar,
+        // so we don't need to do anything here.
         .transpose()?
         .unwrap_or(AnyCalendarKind::Iso))
 }

temporal_capi/bindings/c/AnyCalendarKind.d.h

@@ -18,7 +18,6 @@ pub mod ffi {
         Hebrew,
         Indian,
         HijriTabularTypeIIFriday,
-        HijriSimulatedMecca,
         HijriTabularTypeIIThursday,
         HijriUmmAlQura,
         Iso,
@@ -33,6 +32,8 @@ pub mod ffi {
             let value = icu_locale::extensions::unicode::Value::try_from_utf8(s).ok()?;
             let algorithm = CalendarAlgorithm::try_from(&value).ok()?;
             match icu_calendar::AnyCalendarKind::try_from(algorithm) {
+                // islamic-rgsa / simulated-mecca is supported by ICU4X but not Temporal
+                Ok(icu_calendar::AnyCalendarKind::HijriSimulatedMecca) => None,
                 Ok(c) => Some(c.into()),
                 Err(()) if algorithm == CalendarAlgorithm::Hijri(None) => {
                     Some(Self::HijriTabularTypeIIFriday)