From 0790cac85a8286788bc81f0b294d63e87bad8a86 Mon Sep 17 00:00:00 2001
From: Dan Minor <dminor@mozilla.com>
Date: Wed, 9 Dec 2020 16:50:14 +0000
Subject: [PATCH] Bug 1681357 - Use regional prefs locale if locale is not
 specified in GetDateTimePattern; r=zbraniecki

Differential Revision: https://phabricator.services.mozilla.com/D99241
---
 intl/locale/OSPreferences.cpp                 | 17 +++++++++++++----
 intl/locale/tests/gtest/TestOSPreferences.cpp | 17 ++++++++++++++++-
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/intl/locale/OSPreferences.cpp b/intl/locale/OSPreferences.cpp
index 8f7a72a3c119..9262d7a07155 100644
--- a/intl/locale/OSPreferences.cpp
+++ b/intl/locale/OSPreferences.cpp
@@ -499,8 +499,17 @@ OSPreferences::GetDateTimePattern(int32_t aDateFormatStyle,
     return NS_OK;
   }
 
+  // If the locale is not specified, default to first regional prefs locale
+  const nsACString* locale = &aLocale;
+  AutoTArray<nsCString, 10> rpLocales;
+  if (aLocale.IsEmpty()) {
+    LocaleService::GetInstance()->GetRegionalPrefsLocales(rpLocales);
+    MOZ_ASSERT(rpLocales.Length() > 0);
+    locale = &rpLocales[0];
+  }
+
   // Create a cache key from the locale + style options
-  nsAutoCString key(aLocale);
+  nsAutoCString key(*locale);
   key.Append(':');
   key.AppendInt(aDateFormatStyle);
   key.Append(':');
@@ -512,9 +521,9 @@ OSPreferences::GetDateTimePattern(int32_t aDateFormatStyle,
     return NS_OK;
   }
 
-  if (!OverrideDateTimePattern(dateStyle, timeStyle, aLocale, pattern)) {
-    if (!ReadDateTimePattern(dateStyle, timeStyle, aLocale, pattern)) {
-      if (!GetDateTimePatternForStyle(dateStyle, timeStyle, aLocale, pattern)) {
+  if (!OverrideDateTimePattern(dateStyle, timeStyle, *locale, pattern)) {
+    if (!ReadDateTimePattern(dateStyle, timeStyle, *locale, pattern)) {
+      if (!GetDateTimePatternForStyle(dateStyle, timeStyle, *locale, pattern)) {
         return NS_ERROR_FAILURE;
       }
     }
diff --git a/intl/locale/tests/gtest/TestOSPreferences.cpp b/intl/locale/tests/gtest/TestOSPreferences.cpp
index 3decbe1997c8..605b301c098f 100644
--- a/intl/locale/tests/gtest/TestOSPreferences.cpp
+++ b/intl/locale/tests/gtest/TestOSPreferences.cpp
@@ -77,7 +77,22 @@ TEST(Intl_Locale_OSPreferences, GetDateTimePattern)
     }
   }
 
-  ASSERT_TRUE(1);
+  // If the locale is not specified, we should get the pattern corresponding to
+  // the first regional prefs locale.
+  AutoTArray<nsCString, 10> rpLocales;
+  LocaleService::GetInstance()->GetRegionalPrefsLocales(rpLocales);
+  ASSERT_TRUE(rpLocales.Length() > 0);
+
+  nsAutoCString rpLocalePattern;
+  ASSERT_TRUE(NS_SUCCEEDED(
+      osprefs->GetDateTimePattern(mozIOSPreferences::dateTimeFormatStyleLong,
+                                  mozIOSPreferences::dateTimeFormatStyleLong,
+                                  rpLocales[0], rpLocalePattern)));
+  ASSERT_TRUE(NS_SUCCEEDED(
+      osprefs->GetDateTimePattern(mozIOSPreferences::dateTimeFormatStyleLong,
+                                  mozIOSPreferences::dateTimeFormatStyleLong,
+                                  nsDependentCString(""), pattern)));
+  ASSERT_EQ(rpLocalePattern, pattern);
 }
 
 /**