review comments

Author: Manishearth

components/calendar/src/calendar_arithmetic.rs

@@ -431,7 +431,12 @@ where
     C: DateFieldsResolver<YearInfo = YearInfo>,
 {
     // Check that the year is in range to avoid any arithmetic overflow.
-    range_check(extended_year, "year", -1_000_000..=1_000_000)?;
+    //
+    // This range is currently global, but may be replaced with
+    // a per-calendar check in the future.
+    //
+    // <https://github.com/unicode-org/icu4x/issues/7076>
+    range_check(extended_year, "year", VALID_YEAR_RANGE)?;
     Ok(cal.year_info_from_extended(extended_year))
 }
 
@@ -467,7 +472,7 @@ where
 
         if fields.month_code.is_none() && fields.ordinal_month.is_none() {
             // We're returning this error early so that we return structural type
-            // errors before range errors, see comment in Range.
+            // errors before range errors, see comment in the year code below.
             return Err(DateError::NotEnoughFields);
         }
 

components/calendar/src/date.rs

@@ -149,9 +149,11 @@ impl<A: AsCalendar> Date<A> {
     /// and fill in missing fields. See [`DateFromFieldsOptions`] for more information.
     ///
     /// This function will not accept year/extended_year values that are outside of the range `[-2²⁷, 2²⁷]`,
-    /// regardless of the calendar, instead returning a [`DateError::Range`]. This is to protect clients
-    /// from bugs due to arithmetic overflow. Currently, calendar-specific `Date::try_new_calendarname()` constructors
-    /// do not do this, though we may change that behavior in the future.
+    /// regardless of the calendar, instead returning a [`DateError::Range`]. This is to prevent
+    /// overflowing behaviors near the extreme values of the `i32` range.
+    /// Currently, calendar-specific `Date::try_new_calendarname()` constructors
+    /// do not do this, and it is possible to obtain such extreme dates via calendar conversion or arithmetic,
+    /// though [we may change that behavior in the future](https://github.com/unicode-org/icu4x/issues/7076).
     ///
     /// # Examples
     ///