Bug 1205586 - new Date().toLocale{,Date,Time}String() should return appropriately differing strings as the local time zone/default locale change. r=till

js/src/builtin/Date.js

@@ -5,9 +5,73 @@
 /*global intl_DateTimeFormat: false, */
 
 
+// This cache, once primed, has these properties:
+//
+//   runtimeDefaultLocale:
+//     Locale information provided by the embedding, guiding SpiderMonkey's
+//     selection of a default locale.  See RuntimeDefaultLocale(), whose
+//     value controls the value returned by DefaultLocale() that's what's
+//     *actually* used.
+//   localTZA:
+//     The local time zone's adjustment from UTC.  See LocalTZA().
+//   formatters:
+//     A Record storing formatters consistent with the above
+//     runtimeDefaultLocale/localTZA values, for use with the appropriate
+//     ES6 toLocale*String Date method when called with its first two
+//     arguments having the value |undefined|.
+//
+// The "formatters" Record has (some subset of) these properties, as determined
+// by all values of the first argument passed to |GetCachedFormat|:
+//
+//   dateTimeFormat: for Date's toLocaleString operation
+//   dateFormat: for Date's toLocaleDateString operation
+//   timeFormat: for Date's toLocaleTimeString operation
+//
+// Using this cache, then, requires 1) verifying the current
+// runtimeDefaultLocale/localTZA are consistent with cached values, then
+// 2) seeing if the desired formatter is cached and returning it if so, or else
+// 3) create the desired formatter and store and return it.
 var dateTimeFormatCache = new Record();
 
 
+/**
+ * Get a cached DateTimeFormat formatter object, created like so:
+ *
+ *   var opts = ToDateTimeOptions(undefined, required, defaults);
+ *   return new Intl.DateTimeFormat(undefined, opts);
+ *
+ * |format| must be a key from the "formatters" Record described above.
+ */
+function GetCachedFormat(format, required, defaults) {
+    assert(format === "dateTimeFormat" ||
+           format === "dateFormat" ||
+           format === "timeFormat",
+           "unexpected format key: please update the comment by " +
+           "dateTimeFormatCache");
+
+    var runtimeDefaultLocale = RuntimeDefaultLocale();
+    var localTZA = LocalTZA();
+
+    var formatters;
+    if (dateTimeFormatCache.runtimeDefaultLocale !== runtimeDefaultLocale ||
+        dateTimeFormatCache.localTZA !== localTZA)
+    {
+        formatters = dateTimeFormatCache.formatters = new Record();
+        dateTimeFormatCache.runtimeDefaultLocale = runtimeDefaultLocale;
+        dateTimeFormatCache.localTZA = localTZA;
+    } else {
+        formatters = dateTimeFormatCache.formatters;
+    }
+
+    var fmt = formatters[format];
+    if (fmt === undefined) {
+        var options = ToDateTimeOptions(undefined, required, defaults);
+        fmt = formatters[format] = intl_DateTimeFormat(undefined, options);
+    }
+
+    return fmt;
+}
+
 /**
  * Format this Date object into a date and time string, using the locale and
  * formatting options provided.
@@ -30,11 +94,7 @@ function Date_toLocaleString() {
     if (locales === undefined && options === undefined) {
         // This cache only optimizes for the old ES5 toLocaleString without
         // locales and options.
-        if (dateTimeFormatCache.dateTimeFormat === undefined) {
-            options = ToDateTimeOptions(options, "any", "all");
-            dateTimeFormatCache.dateTimeFormat = intl_DateTimeFormat(locales, options);
-        }
-        dateTimeFormat = dateTimeFormatCache.dateTimeFormat;
+        dateTimeFormat = GetCachedFormat("dateTimeFormat", "any", "all");
     } else {
         options = ToDateTimeOptions(options, "any", "all");
         dateTimeFormat = intl_DateTimeFormat(locales, options);
@@ -67,11 +127,7 @@ function Date_toLocaleDateString() {
     if (locales === undefined && options === undefined) {
         // This cache only optimizes for the old ES5 toLocaleDateString without
         // locales and options.
-        if (dateTimeFormatCache.dateFormat === undefined) {
-            options = ToDateTimeOptions(options, "date", "date");
-            dateTimeFormatCache.dateFormat = intl_DateTimeFormat(locales, options);
-        }
-        dateTimeFormat = dateTimeFormatCache.dateFormat;
+        dateTimeFormat = GetCachedFormat("dateFormat", "date", "date");
     } else {
         options = ToDateTimeOptions(options, "date", "date");
         dateTimeFormat = intl_DateTimeFormat(locales, options);
@@ -104,11 +160,7 @@ function Date_toLocaleTimeString() {
     if (locales === undefined && options === undefined) {
         // This cache only optimizes for the old ES5 toLocaleTimeString without
         // locales and options.
-        if (dateTimeFormatCache.timeFormat === undefined) {
-            options = ToDateTimeOptions(options, "time", "time");
-            dateTimeFormatCache.timeFormat = intl_DateTimeFormat(locales, options);
-        }
-        dateTimeFormat = dateTimeFormatCache.timeFormat;
+        dateTimeFormat = GetCachedFormat("timeFormat", "time", "time");
     } else {
         options = ToDateTimeOptions(options, "time", "time");
         dateTimeFormat = intl_DateTimeFormat(locales, options);

js/src/jsapi-tests/moz.build

@@ -18,6 +18,7 @@ UNIFIED_SOURCES += [
     'testClassGetter.cpp',
     'testCloneScript.cpp',
     'testContexts.cpp',
+    'testDateToLocaleString.cpp',
     'testDebugger.cpp',
     'testDeepFreeze.cpp',
     'testDefineGetterSetterNonEnumerable.cpp',

js/src/jsapi-tests/testDateToLocaleString.cpp

@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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 "jsapi-tests/tests.h"
+
+BEGIN_TEST(testDateToLocaleString)
+{
+    // This test should only attempt to run if we have Intl support: necessary
+    // to properly assume that changes to the default locale will predictably
+    // affect the behavior of the locale-sensitive Date methods tested here.
+    JS::Rooted<JS::Value> haveIntl(cx);
+    EVAL("typeof Intl !== 'undefined'", &haveIntl);
+    if (!haveIntl.toBoolean())
+        return true;
+
+    // Pervasive assumption: our Intl support includes "de" (German) and
+    // "en" (English) and treats them differently for purposes of
+    // Date.prototype.toLocale{,Date,Time}String behavior.
+
+    // Start with German.
+    CHECK(JS_SetDefaultLocale(rt, "de"));
+
+    // The (constrained) Date object we'll use to test behavior.
+    EXEC("var d = new Date(Date.UTC(2015, 9 - 1, 17));");
+
+    // Test that toLocaleString behavior changes with default locale changes.
+    EXEC("var deAll = d.toLocaleString();");
+
+    CHECK(JS_SetDefaultLocale(rt, "en"));
+    EXEC("if (d.toLocaleString() === deAll) \n"
+         "  throw 'toLocaleString results should have changed with system locale change';");
+
+    // Test that toLocaleDateString behavior changes with default locale changes.
+    EXEC("var enDate = d.toLocaleDateString();");
+
+    CHECK(JS_SetDefaultLocale(rt, "de"));
+    EXEC("if (d.toLocaleDateString() === enDate) \n"
+         "  throw 'toLocaleDateString results should have changed with system locale change';");
+
+    // Test that toLocaleTimeString behavior changes with default locale changes.
+    EXEC("var deTime = d.toLocaleTimeString();");
+
+    CHECK(JS_SetDefaultLocale(rt, "en"));
+    EXEC("if (d.toLocaleTimeString() === deTime) \n"
+         "  throw 'toLocaleTimeString results should have changed with system locale change';");
+
+    JS_ResetDefaultLocale(rt);
+    return true;
+}
+END_TEST(testDateToLocaleString)

js/src/vm/SelfHosting.cpp

@@ -1204,6 +1204,16 @@ intrinsic_RuntimeDefaultLocale(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
+static bool
+intrinsic_LocalTZA(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    MOZ_ASSERT(args.length() == 0, "the LocalTZA intrinsic takes no arguments");
+
+    args.rval().setDouble(cx->runtime()->dateTimeInfo.localTZA());
+    return true;
+}
+
 static bool
 intrinsic_IsConstructing(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -1324,6 +1334,7 @@ static const JSFunctionSpec intrinsic_functions[] = {
     JS_FN("_ConstructorForTypedArray", intrinsic_ConstructorForTypedArray, 1,0),
     JS_FN("DecompileArg",            intrinsic_DecompileArg,            2,0),
     JS_FN("RuntimeDefaultLocale",    intrinsic_RuntimeDefaultLocale,    0,0),
+    JS_FN("LocalTZA",                intrinsic_LocalTZA,                0,0),
 
     JS_INLINABLE_FN("_IsConstructing", intrinsic_IsConstructing,        0,0,
                     IntrinsicIsConstructing),