[ddc] Copy JS 2-digit year handling from dart2js.
Fixes https://github.com/dart-lang/sdk/issues/42894
Change-Id: I68a8782d123c299ec34bfd0a31b3108138dac117
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/164681
Reviewed-by: Riley Porter <rileyporter@google.com>
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Commit-Queue: Riley Porter <rileyporter@google.com>
diff --git a/sdk/lib/_internal/js_dev_runtime/private/js_helper.dart b/sdk/lib/_internal/js_dev_runtime/private/js_helper.dart
index 11a3a8e..83815d9 100644
--- a/sdk/lib/_internal/js_dev_runtime/private/js_helper.dart
+++ b/sdk/lib/_internal/js_dev_runtime/private/js_helper.dart
@@ -354,6 +354,14 @@
@nullCheck bool isUtc) {
final int MAX_MILLISECONDS_SINCE_EPOCH = 8640000000000000;
var jsMonth = month - 1;
+ // The JavaScript Date constructor 'corrects' year NN to 19NN. Sidestep that
+ // correction by adjusting years out of that range and compensating with an
+ // adjustment of months. This hack should not be sensitive to leap years but
+ // use 400 just in case.
+ if (0 <= years && years < 100) {
+ years += 400;
+ jsMonth -= 400 * 12;
+ }
int value;
if (isUtc) {
value = JS<int>('!', r'Date.UTC(#, #, #, #, #, #, #)', years, jsMonth,
diff --git a/tests/corelib/date_time_js_modified_test.dart b/tests/corelib/date_time_js_modified_test.dart
new file mode 100644
index 0000000..92f4b77
--- /dev/null
+++ b/tests/corelib/date_time_js_modified_test.dart
@@ -0,0 +1,16 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "package:expect/expect.dart";
+
+// The JavaScript Date constructor 'corrects' 2-digit years NN to 19NN.
+// Verify that a DateTime with year 1 is created correctly.
+// Regression test for https://github.com/dart-lang/sdk/issues/42894
+
+main() {
+ var d = new DateTime(1, 0, 1, 0, 0, 0, 0);
+ var d2 = new DateTime(0, 12, 1, 0, 0, 0, 0);
+
+ Expect.equals(d, d2);
+}
diff --git a/tests/corelib_2/date_time_js_modified_test.dart b/tests/corelib_2/date_time_js_modified_test.dart
new file mode 100644
index 0000000..92f4b77
--- /dev/null
+++ b/tests/corelib_2/date_time_js_modified_test.dart
@@ -0,0 +1,16 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "package:expect/expect.dart";
+
+// The JavaScript Date constructor 'corrects' 2-digit years NN to 19NN.
+// Verify that a DateTime with year 1 is created correctly.
+// Regression test for https://github.com/dart-lang/sdk/issues/42894
+
+main() {
+ var d = new DateTime(1, 0, 1, 0, 0, 0, 0);
+ var d2 = new DateTime(0, 12, 1, 0, 0, 0, 0);
+
+ Expect.equals(d, d2);
+}
