Change LeapStatus::StandardAfterLeap to ::LeapBase (#7701)

Author: robertbastian

components/calendar/src/cal/east_asian_traditional.rs

@@ -760,7 +760,11 @@ impl<R: Rules> Calendar for EastAsianTraditional<R> {
     /// leap months. For example, in a year where an intercalary month is added after the second
     /// month, the month codes for ordinal months 1, 2, 3, 4, 5 would be "M01", "M02", "M02L", "M03", "M04".
     fn month(&self, date: &Self::DateInner) -> types::MonthInfo {
-        types::MonthInfo::new(self, date.0)
+        let mut m = types::MonthInfo::new(self, date.0);
+        if date.0.year().packed.leap_month() == Some(m.ordinal + 1) {
+            m.leap_status = types::LeapStatus::LeapBase;
+        }
+        m
     }
 
     /// The calendar-specific day-of-month represented by `date`

components/calendar/src/cal/hebrew.rs

@@ -325,10 +325,17 @@ impl Calendar for Hebrew {
 
     fn month(&self, date: &Self::DateInner) -> MonthInfo {
         let mut m = MonthInfo::new(self, date.0);
-        #[allow(deprecated)]
+        // Even though the leap month is modeled as M05L,
+        // the actual leap base is M06.
         if m.number() == 6 && m.ordinal == 7 {
-            m.leap_status = LeapStatus::StandardAfterLeap;
-            m.formatting_code = Month::leap(6).code();
+            m.leap_status = LeapStatus::LeapBase;
+            #[allow(deprecated)]
+            {
+                // This is an ICU4X invention, it's not needed by
+                // formatting anymore, but we keep producing it
+                // for now.
+                m.formatting_code = Month::leap(6).code();
+            }
         }
         m
     }

components/calendar/src/types.rs

@@ -493,12 +493,14 @@ pub enum LeapStatus {
     Normal,
     /// A leap month.
     Leap,
-    /// A month that is not itself considered a leap month, but might
-    /// have special formatting because it occurs after a leap month.
-    ///
-    /// An example of this is the Hebrew month "Adar", which is called
-    /// "Adar II" when it follows the leap month "Adar I".
-    StandardAfterLeap,
+    /// A standard month that has a corresponding leap month
+    /// in the same year.
+    ///
+    /// "Corresponding" is used in a formatting sense here:
+    /// even though the Hebrew "Adar I" is `M05L`, the
+    /// `LeapBase` will be `M06` (not `M05`), so formatting
+    /// knows to produce "Adar II".
+    LeapBase,
 }
 
 impl Month {

components/datetime/src/pattern/names.rs

@@ -3781,7 +3781,13 @@ impl RawDateTimeNamesBorrowed<'_> {
             }
             MonthNames::LeapLinear(leap_linear) => {
                 let num_months = leap_linear.len() / 2;
-                if month.leap_status() != LeapStatus::Normal {
+                if month.leap_status() == LeapStatus::Leap {
+                    leap_linear.get(month_index + num_months)
+                } else if month.leap_status() == LeapStatus::LeapBase
+                    && month.number() < month.ordinal
+                {
+                    // Detects Hebrew (base after leap) vs Chinese (base before leap).
+                    // In Hebrew, we use leap names for LeapBase months.
                     leap_linear.get(month_index + num_months)
                 } else if month_index < num_months {
                     leap_linear.get(month_index)

components/datetime/tests/fixtures/tests/components.json

@@ -54,6 +54,35 @@
             }
         }
     },
+    {
+        "input": {
+            "value": "2023-03-10T14:15:07.123",
+            "options": {
+                "components": {
+                    "weekday": "long",
+                    "month": "long",
+                    "day": "two-digit-day-of-month",
+                    "era": "long",
+                    "year": "numeric",
+                    "hour": "numeric",
+                    "minute": "numeric",
+                    "second": "numeric"
+                },
+                "semantic": {
+                    "dateFields": "YMDE",
+                    "length": "long",
+                    "timePrecision": "second",
+                    "yearStyle": "withEra"
+                }
+            }
+        },
+        "output": {
+            "values": {
+                "en-u-ca-chinese-hc-h23": "Friday, Second Month 19, 2023(gui-mao) at 14:15:07",
+                "zh-u-ca-chinese-hc-h23": "2023癸卯年二月19星期五 14:15:07"
+            }
+        }
+    },
     {
         "input": {
             "value": "2023-03-23T14:15:07.123",