Bug 1954138 - Part 2: Set Gregorian change date when constructing formatters. r=dminor

Always reset the Gregorian change date, because all uses either require the
Gregorian change date to be set to `-8.64e15` or don't care about dates far
into the past.

The slow `DateIntervalFormat::TryFormatCalendar` is now only used when
`MOZ_SYSTEM_ICU` is defined.

And also resets the Gregorian change date for "buddhist", "japanese", and
"roc" to get consistent results when compared to the ICU4X-based Temporal
code.

Differential Revision: https://phabricator.services.mozilla.com/D241644

intl/components/gtest/TestDateTimeFormat.cpp

@@ -574,9 +574,6 @@ TEST(IntlDateTimeFormat, SetStartTimeIfGregorian)
 
   auto timeZone = Some(MakeStringSpan(u"UTC"));
 
-  // Beginning of ECMAScript time.
-  constexpr double StartOfTime = -8.64e15;
-
   // Gregorian change date defaults to October 15, 1582 in ICU. Test with a date
   // before the default change date, in this case January 1, 1582.
   constexpr double FirstJanuary1582 = -12244089600000.0;
@@ -597,38 +594,25 @@ TEST(IntlDateTimeFormat, SetStartTimeIfGregorian)
                         MakeStringSpan(locale), style, gen.get(), timeZone)
                         .unwrap();
 
-    const char* Dec22_1581;
     const char* Jan01_1582;
     const char* Jan01_1583;
     if (locale == "en-US-u-ca-iso8601"sv) {
-      Dec22_1581 = "1581 December 22";
       Jan01_1582 = "1582 January 1";
       Jan01_1583 = "1583 January 1";
     } else {
-      Dec22_1581 = "December 22, 1581";
       Jan01_1582 = "January 1, 1582";
       Jan01_1583 = "January 1, 1583";
     }
 
     TestBuffer<char> buffer;
 
-    // Before the default Gregorian change date, so interpreted in the Julian
-    // calendar, which is December 22, 1581.
-    dtFormat->TryFormat(FirstJanuary1582, buffer).unwrap();
-    ASSERT_TRUE(buffer.verboseMatches(Dec22_1581));
-
-    // After default Gregorian change date, so January 1, 1583.
-    dtFormat->TryFormat(FirstJanuary1582 + oneYear, buffer).unwrap();
-    ASSERT_TRUE(buffer.verboseMatches(Jan01_1583));
-
-    // Adjust the start time to use a proleptic Gregorian calendar.
-    dtFormat->SetStartTimeIfGregorian(StartOfTime);
-
-    // Now interpreted in proleptic Gregorian calendar at January 1, 1582.
+    // Before the default Gregorian change date, but not interpreted in the
+    // Julian calendar, which is December 22, 1581. Instead interpreted in
+    // proleptic Gregorian calendar at January 1, 1582.
     dtFormat->TryFormat(FirstJanuary1582, buffer).unwrap();
     ASSERT_TRUE(buffer.verboseMatches(Jan01_1582));
 
-    // Still January 1, 1583.
+    // After default Gregorian change date, so January 1, 1583.
     dtFormat->TryFormat(FirstJanuary1582 + oneYear, buffer).unwrap();
     ASSERT_TRUE(buffer.verboseMatches(Jan01_1583));
   }

intl/components/src/DateIntervalFormat.cpp

@@ -2,12 +2,18 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "DateTimeFormat.h"  // for DATE_TIME_FORMAT_REPLACE_SPECIAL_SPACES
 #include "DateTimeFormatUtils.h"
 #include "ScopedICUObject.h"
 
 #include "mozilla/intl/Calendar.h"
 #include "mozilla/intl/DateIntervalFormat.h"
+#include "mozilla/intl/DateTimeFormat.h"
+
+#if !MOZ_SYSTEM_ICU
+#  include "unicode/calendar.h"
+#  include "unicode/datefmt.h"
+#  include "unicode/dtitvfmt.h"
+#endif
 
 namespace mozilla::intl {
 
@@ -63,7 +69,23 @@ Result<UniquePtr<DateIntervalFormat>, ICUError> DateIntervalFormat::TryCreate(
     return Err(ToICUError(status));
   }
 
-  return UniquePtr<DateIntervalFormat>(new DateIntervalFormat(dif));
+  auto result = UniquePtr<DateIntervalFormat>(new DateIntervalFormat(dif));
+
+#if !MOZ_SYSTEM_ICU
+  auto* dtif = reinterpret_cast<icu::DateIntervalFormat*>(dif);
+  const icu::Calendar* calendar = dtif->getDateFormat()->getCalendar();
+
+  auto replacement = CreateCalendarOverride(calendar);
+  if (replacement.isErr()) {
+    return replacement.propagateErr();
+  }
+
+  if (auto newCalendar = replacement.unwrap()) {
+    dtif->adoptCalendar(newCalendar.release());
+  }
+#endif
+
+  return result;
 }
 
 DateIntervalFormat::~DateIntervalFormat() {
@@ -133,6 +155,50 @@ ICUResult DateIntervalFormat::TryFormatDateTime(
   return Ok();
 }
 
+ICUResult DateIntervalFormat::TryFormatDateTime(
+    double aStart, double aEnd, const DateTimeFormat* aDateTimeFormat,
+    AutoFormattedDateInterval& aFormatted, bool* aPracticallyEqual) const {
+#if MOZ_SYSTEM_ICU
+  // We can't access the calendar used by UDateIntervalFormat to change it to a
+  // proleptic Gregorian calendar. Instead we need to call a different formatter
+  // function which accepts UCalendar instead of UDate.
+  // But creating new UCalendar objects for each call is slow, so when we can
+  // ensure that the input dates are later than the Gregorian change date,
+  // directly call the formatter functions taking UDate.
+
+  constexpr int32_t msPerDay = 24 * 60 * 60 * 1000;
+
+  // The Gregorian change date "1582-10-15T00:00:00.000Z".
+  constexpr double GregorianChangeDate = -12219292800000.0;
+
+  // Add a full day to account for time zone offsets.
+  constexpr double GregorianChangeDatePlusOneDay =
+      GregorianChangeDate + msPerDay;
+
+  if (aStart < GregorianChangeDatePlusOneDay ||
+      aEnd < GregorianChangeDatePlusOneDay) {
+    // Create calendar objects for the start and end date by cloning the date
+    // formatter calendar. The date formatter calendar already has the correct
+    // time zone set and was changed to use a proleptic Gregorian calendar.
+    auto startCal = aDateTimeFormat->CloneCalendar(aStart);
+    if (startCal.isErr()) {
+      return startCal.propagateErr();
+    }
+
+    auto endCal = aDateTimeFormat->CloneCalendar(aEnd);
+    if (endCal.isErr()) {
+      return endCal.propagateErr();
+    }
+
+    return TryFormatCalendar(*startCal.unwrap(), *endCal.unwrap(), aFormatted,
+                             aPracticallyEqual);
+  }
+#endif
+
+  // The common fast path which doesn't require creating calendar objects.
+  return TryFormatDateTime(aStart, aEnd, aFormatted, aPracticallyEqual);
+}
+
 ICUResult DateIntervalFormat::TryFormattedToParts(
     const AutoFormattedDateInterval& aFormatted,
     DateTimePartVector& aParts) const {

intl/components/src/DateIntervalFormat.h

@@ -17,6 +17,7 @@
 
 namespace mozilla::intl {
 class Calendar;
+class DateTimeFormat;
 
 using AutoFormattedDateInterval =
     AutoFormattedResult<UFormattedDateInterval, udtitvfmt_openResult,
@@ -79,6 +80,21 @@ class DateIntervalFormat final {
                               AutoFormattedDateInterval& aFormatted,
                               bool* aPracticallyEqual) const;
 
+  /**
+   * Format a date-time range between two Unix epoch times in milliseconds.
+   *
+   * The result will be stored in aFormatted, caller can use
+   * AutoFormattedDateInterval::ToSpan() to get the formatted string, or pass
+   * the aFormatted to TryFormattedToParts to get the parts vector.
+   *
+   * aPracticallyEqual will be set to true if the date times of the two
+   * Unix epoch times are equal.
+   */
+  ICUResult TryFormatDateTime(double aStart, double aEnd,
+                              const DateTimeFormat* aDateTimeFormat,
+                              AutoFormattedDateInterval& aFormatted,
+                              bool* aPracticallyEqual) const;
+
   /**
    *  Convert the formatted DateIntervalFormat into several parts.
    *

intl/components/src/DateTimeFormat.cpp

@@ -279,6 +279,8 @@ Result<UniquePtr<DateTimeFormat>, ICUError> DateTimeFormat::TryCreateFromStyle(
     return Err(ToICUError(status));
   }
 
+  MOZ_TRY(ApplyCalendarOverride(dateFormat));
+
   auto df = UniquePtr<DateTimeFormat>(new DateTimeFormat(dateFormat));
 
   if (aStyleBag.time && (aStyleBag.hour12 || aStyleBag.hourCycle)) {
@@ -564,11 +566,12 @@ DateTimeFormat::TryCreateFromPattern(
   UDateFormat* dateFormat = udat_open(
       UDAT_PATTERN, UDAT_PATTERN, IcuLocale(aLocale), tzID, tzIDLength,
       aPattern.data(), static_cast<int32_t>(aPattern.size()), &status);
-
   if (U_FAILURE(status)) {
     return Err(ToICUError(status));
   }
 
+  MOZ_TRY(ApplyCalendarOverride(dateFormat));
+
   // The DateTimeFormat wrapper will control the life cycle of the ICU
   // dateFormat object.
   return UniquePtr<DateTimeFormat>(new DateTimeFormat(dateFormat));
@@ -612,13 +615,6 @@ ICUResult DateTimeFormat::CacheSkeleton(Span<const char16_t> aSkeleton) {
   return Err(ICUError::OutOfMemory);
 }
 
-void DateTimeFormat::SetStartTimeIfGregorian(double aTime) {
-  UErrorCode status = U_ZERO_ERROR;
-  UCalendar* cal = const_cast<UCalendar*>(udat_getCalendar(mDateFormat));
-  ucal_setGregorianChange(cal, aTime, &status);
-  // An error here means the calendar is not Gregorian, and can be ignored.
-}
-
 /* static */
 Result<UniquePtr<Calendar>, ICUError> DateTimeFormat::CloneCalendar(
     double aUnixEpoch) const {

intl/components/src/DateTimeFormat.h

@@ -477,12 +477,6 @@ class DateTimeFormat final {
     }
     return Ok();
   }
-  /**
-   * Set the start time of the Gregorian calendar. This is useful for
-   * ensuring the consistent use of a proleptic Gregorian calendar for ECMA-402.
-   * https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar
-   */
-  void SetStartTimeIfGregorian(double aTime);
 
   /**
    * Determines the resolved components for the current DateTimeFormat.

intl/components/src/DateTimeFormatUtils.cpp

@@ -3,8 +3,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/Assertions.h"
+#include "mozilla/Try.h"
 
 #include "DateTimeFormatUtils.h"
+#include "mozilla/intl/ICU4CGlue.h"
+
+#include <cstring>
+
+#if !MOZ_SYSTEM_ICU
+#  include "unicode/datefmt.h"
+#  include "unicode/gregocal.h"
+#endif
 
 namespace mozilla::intl {
 
@@ -101,4 +110,74 @@ DateTimePartType ConvertUFormatFieldToPartType(UDateFormatField fieldName) {
   return DateTimePartType::Unknown;
 }
 
+// Start of ECMAScript time.
+static constexpr double StartOfTime = -8.64e15;
+
+#if !MOZ_SYSTEM_ICU
+static bool IsGregorianLikeCalendar(const char* type) {
+  return std::strcmp(type, "gregorian") == 0 ||
+         std::strcmp(type, "iso8601") == 0 ||
+         std::strcmp(type, "buddhist") == 0 ||
+         std::strcmp(type, "japanese") == 0 || std::strcmp(type, "roc") == 0;
+}
+
+/**
+ * Set the start time of the Gregorian calendar. This is useful for
+ * ensuring the consistent use of a proleptic Gregorian calendar for ECMA-402.
+ * https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar
+ */
+static Result<Ok, ICUError> SetGregorianChangeDate(
+    icu::GregorianCalendar* gregorian) {
+  UErrorCode status = U_ZERO_ERROR;
+  gregorian->setGregorianChange(StartOfTime, status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+  return Ok{};
+}
+#endif
+
+Result<Ok, ICUError> ApplyCalendarOverride(UDateFormat* aDateFormat) {
+#if !MOZ_SYSTEM_ICU
+  icu::DateFormat* df = reinterpret_cast<icu::DateFormat*>(aDateFormat);
+  const icu::Calendar* calendar = df->getCalendar();
+
+  const char* type = calendar->getType();
+
+  if (IsGregorianLikeCalendar(type)) {
+    auto* gregorian = static_cast<const icu::GregorianCalendar*>(calendar);
+    MOZ_TRY(
+        SetGregorianChangeDate(const_cast<icu::GregorianCalendar*>(gregorian)));
+  }
+#else
+  UErrorCode status = U_ZERO_ERROR;
+  UCalendar* cal = const_cast<UCalendar*>(udat_getCalendar(aDateFormat));
+  ucal_setGregorianChange(cal, StartOfTime, &status);
+  // An error here means the calendar is not Gregorian, and can be ignored.
+#endif
+
+  return Ok{};
+}
+
+#if !MOZ_SYSTEM_ICU
+Result<UniquePtr<icu::Calendar>, ICUError> CreateCalendarOverride(
+    const icu::Calendar* calendar) {
+  const char* type = calendar->getType();
+
+  if (IsGregorianLikeCalendar(type)) {
+    UniquePtr<icu::GregorianCalendar> gregorian(
+        static_cast<const icu::GregorianCalendar*>(calendar)->clone());
+    if (!gregorian) {
+      return Err(ICUError::OutOfMemory);
+    }
+
+    MOZ_TRY(SetGregorianChangeDate(gregorian.get()));
+
+    return UniquePtr<icu::Calendar>{gregorian.release()};
+  }
+
+  return UniquePtr<icu::Calendar>{};
+}
+#endif
+
 }  // namespace mozilla::intl

intl/components/src/DateTimeFormatUtils.h

@@ -5,10 +5,24 @@
 #define intl_components_DateTimeFormatUtils_h_
 #include "unicode/udat.h"
 
+#if !MOZ_SYSTEM_ICU
+#  include "unicode/calendar.h"
+#endif
+
+#include "mozilla/Result.h"
+#include "mozilla/UniquePtr.h"
 #include "mozilla/intl/DateTimePart.h"
+#include "mozilla/intl/ICUError.h"
 
 namespace mozilla::intl {
 DateTimePartType ConvertUFormatFieldToPartType(UDateFormatField fieldName);
+
+Result<Ok, ICUError> ApplyCalendarOverride(UDateFormat* aDateFormat);
+
+#if !MOZ_SYSTEM_ICU
+Result<UniquePtr<icu::Calendar>, ICUError> CreateCalendarOverride(
+    const icu::Calendar* calendar);
+#endif
 }  // namespace mozilla::intl
 
 #endif

js/src/builtin/intl/DateTimeFormat.cpp

@@ -1638,10 +1638,6 @@ static mozilla::intl::DateTimeFormat* NewDateTimeFormat(
     df = dfResult.unwrap();
   }
 
-  // ECMAScript requires the Gregorian calendar to be used from the beginning
-  // of ECMAScript time.
-  df->SetStartTimeIfGregorian(StartOfTime);
-
   return df.release();
 }
 
@@ -2578,51 +2574,12 @@ static bool PartitionDateTimeRangePattern(
   MOZ_ASSERT(x.isValid());
   MOZ_ASSERT(y.isValid());
 
-  // We can't access the calendar used by UDateIntervalFormat to change it to a
-  // proleptic Gregorian calendar. Instead we need to call a different formatter
-  // function which accepts UCalendar instead of UDate.
-  // But creating new UCalendar objects for each call is slow, so when we can
-  // ensure that the input dates are later than the Gregorian change date,
-  // directly call the formatter functions taking UDate.
-
-  // The Gregorian change date "1582-10-15T00:00:00.000Z".
-  constexpr double GregorianChangeDate = -12219292800000.0;
-
-  // Add a full day to account for time zone offsets.
-  constexpr double GregorianChangeDatePlusOneDay =
-      GregorianChangeDate + msPerDay;
-
-  mozilla::intl::ICUResult result = Ok();
-  if (x.toDouble() < GregorianChangeDatePlusOneDay ||
-      y.toDouble() < GregorianChangeDatePlusOneDay) {
-    // Create calendar objects for the start and end date by cloning the date
-    // formatter calendar. The date formatter calendar already has the correct
-    // time zone set and was changed to use a proleptic Gregorian calendar.
-    auto startCal = df->CloneCalendar(x.toDouble());
-    if (startCal.isErr()) {
-      intl::ReportInternalError(cx, startCal.unwrapErr());
-      return false;
-    }
-
-    auto endCal = df->CloneCalendar(y.toDouble());
-    if (endCal.isErr()) {
-      intl::ReportInternalError(cx, endCal.unwrapErr());
-      return false;
-    }
-
-    result = dif->TryFormatCalendar(*startCal.unwrap(), *endCal.unwrap(),
-                                    formatted, equal);
-  } else {
-    // The common fast path which doesn't require creating calendar objects.
-    result =
-        dif->TryFormatDateTime(x.toDouble(), y.toDouble(), formatted, equal);
-  }
-
+  auto result =
+      dif->TryFormatDateTime(x.toDouble(), y.toDouble(), df, formatted, equal);
   if (result.isErr()) {
     intl::ReportInternalError(cx, result.unwrapErr());
     return false;
   }
-
   return true;
 }