Migrate language_2/canonicalize to NNBD.

Change-Id: I603740794fc286527f7f37c0d57feb9b57157784
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/141661
Auto-Submit: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
Commit-Queue: Bob Nystrom <rnystrom@google.com>

tests/language/canonicalize/const2_test.dart

@@ -0,0 +1,11 @@
+// Copyright (c) 2011, 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";
+
+// Check that compile-time constants are correctly canonicalized.
+
+main() {
+  Expect.isFalse(identical(const <num>[1, 2], const <num>[1.0, 2.0]));
+}

tests/language/canonicalize/const3_test.dart

@@ -0,0 +1,31 @@
+// Copyright (c) 2013, 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.
+//
+// Check proper canonicalization (fields must be canonicalized as well).
+
+import "package:expect/expect.dart";
+
+main() {
+  Expect.isFalse(identical(new Duration(days: 1), new Duration(days: 1)));
+  Expect.isTrue(identical(const Duration(days: 2), const Duration(days: 2)));
+  Expect.isTrue(identical(const B(3.0), const B(3.0)));
+  Expect.isTrue(identical(const F(main), const F(main)));
+}
+
+class A {
+  final a;
+  const A(v) : a = v + 3.4;
+}
+
+class B extends A {
+  final b;
+  const B(v)
+      : b = v + 1.0,
+        super(v);
+}
+
+class F {
+  final f;
+  const F(v) : f = v;
+}

tests/language/canonicalize/const_test.dart

@@ -0,0 +1,44 @@
+// Copyright (c) 2011, 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.
+// Check that initializers of static const fields are compile time constants.
+
+import "package:expect/expect.dart";
+
+class CanonicalConstTest {
+  static const A = const C1();
+  static const B = const C2();
+
+  static testMain() {
+    Expect.identical(null, null);
+    Expect.isFalse(identical(null, 0));
+    Expect.identical(1, 1);
+    Expect.isFalse(identical(1, 2));
+    Expect.identical(true, true);
+    Expect.identical("so", "so");
+    Expect.identical(const Object(), const Object());
+    Expect.isFalse(identical(const Object(), const C1()));
+    Expect.identical(const C1(), const C1());
+    Expect.identical(A, const C1());
+    Expect.isFalse(identical(const C1(), const C2()));
+    Expect.identical(B, const C2());
+    Expect.isFalse(identical(const [2, 1], const [1, 2]));
+    Expect.identical(const <int>[1, 2], const <int>[1, 2]);
+    Expect.identical(const <Object>[1, 2], const <Object>[1, 2]);
+    Expect.isFalse(identical(const <int>[1, 2], const <double>[1.0, 2.0]));
+    Expect.identical(const {"a": 1, "b": 2}, const {"a": 1, "b": 2});
+    Expect.isFalse(identical(const {"a": 1, "b": 2}, const {"a": 2, "b": 2}));
+  }
+}
+
+class C1 {
+  const C1();
+}
+
+class C2 extends C1 {
+  const C2() : super();
+}
+
+main() {
+  CanonicalConstTest.testMain();
+}

tests/language/canonicalize/hashing_memoize_array_test.dart

@@ -0,0 +1,218 @@
+// Copyright (c) 2019, 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.
+
+// If canonicalization uses deep structural hashing without memoizing, this
+// will exhibit superlinear time.
+
+const list1_0 = <Object?>[null, null];
+const list1_1 = <Object?>[list1_0, list1_0];
+const list1_2 = <Object?>[list1_1, list1_1];
+const list1_3 = <Object?>[list1_2, list1_2];
+const list1_4 = <Object?>[list1_3, list1_3];
+const list1_5 = <Object?>[list1_4, list1_4];
+const list1_6 = <Object?>[list1_5, list1_5];
+const list1_7 = <Object?>[list1_6, list1_6];
+const list1_8 = <Object?>[list1_7, list1_7];
+const list1_9 = <Object?>[list1_8, list1_8];
+const list1_10 = <Object?>[list1_9, list1_9];
+const list1_11 = <Object?>[list1_10, list1_10];
+const list1_12 = <Object?>[list1_11, list1_11];
+const list1_13 = <Object?>[list1_12, list1_12];
+const list1_14 = <Object?>[list1_13, list1_13];
+const list1_15 = <Object?>[list1_14, list1_14];
+const list1_16 = <Object?>[list1_15, list1_15];
+const list1_17 = <Object?>[list1_16, list1_16];
+const list1_18 = <Object?>[list1_17, list1_17];
+const list1_19 = <Object?>[list1_18, list1_18];
+const list1_20 = <Object?>[list1_19, list1_19];
+const list1_21 = <Object?>[list1_20, list1_20];
+const list1_22 = <Object?>[list1_21, list1_21];
+const list1_23 = <Object?>[list1_22, list1_22];
+const list1_24 = <Object?>[list1_23, list1_23];
+const list1_25 = <Object?>[list1_24, list1_24];
+const list1_26 = <Object?>[list1_25, list1_25];
+const list1_27 = <Object?>[list1_26, list1_26];
+const list1_28 = <Object?>[list1_27, list1_27];
+const list1_29 = <Object?>[list1_28, list1_28];
+const list1_30 = <Object?>[list1_29, list1_29];
+const list1_31 = <Object?>[list1_30, list1_30];
+const list1_32 = <Object?>[list1_31, list1_31];
+const list1_33 = <Object?>[list1_32, list1_32];
+const list1_34 = <Object?>[list1_33, list1_33];
+const list1_35 = <Object?>[list1_34, list1_34];
+const list1_36 = <Object?>[list1_35, list1_35];
+const list1_37 = <Object?>[list1_36, list1_36];
+const list1_38 = <Object?>[list1_37, list1_37];
+const list1_39 = <Object?>[list1_38, list1_38];
+const list1_40 = <Object?>[list1_39, list1_39];
+const list1_41 = <Object?>[list1_40, list1_40];
+const list1_42 = <Object?>[list1_41, list1_41];
+const list1_43 = <Object?>[list1_42, list1_42];
+const list1_44 = <Object?>[list1_43, list1_43];
+const list1_45 = <Object?>[list1_44, list1_44];
+const list1_46 = <Object?>[list1_45, list1_45];
+const list1_47 = <Object?>[list1_46, list1_46];
+const list1_48 = <Object?>[list1_47, list1_47];
+const list1_49 = <Object?>[list1_48, list1_48];
+const list1_50 = <Object?>[list1_49, list1_49];
+const list1_51 = <Object?>[list1_50, list1_50];
+const list1_52 = <Object?>[list1_51, list1_51];
+const list1_53 = <Object?>[list1_52, list1_52];
+const list1_54 = <Object?>[list1_53, list1_53];
+const list1_55 = <Object?>[list1_54, list1_54];
+const list1_56 = <Object?>[list1_55, list1_55];
+const list1_57 = <Object?>[list1_56, list1_56];
+const list1_58 = <Object?>[list1_57, list1_57];
+const list1_59 = <Object?>[list1_58, list1_58];
+const list1_60 = <Object?>[list1_59, list1_59];
+const list1_61 = <Object?>[list1_60, list1_60];
+const list1_62 = <Object?>[list1_61, list1_61];
+const list1_63 = <Object?>[list1_62, list1_62];
+const list1_64 = <Object?>[list1_63, list1_63];
+const list1_65 = <Object?>[list1_64, list1_64];
+const list1_66 = <Object?>[list1_65, list1_65];
+const list1_67 = <Object?>[list1_66, list1_66];
+const list1_68 = <Object?>[list1_67, list1_67];
+const list1_69 = <Object?>[list1_68, list1_68];
+const list1_70 = <Object?>[list1_69, list1_69];
+const list1_71 = <Object?>[list1_70, list1_70];
+const list1_72 = <Object?>[list1_71, list1_71];
+const list1_73 = <Object?>[list1_72, list1_72];
+const list1_74 = <Object?>[list1_73, list1_73];
+const list1_75 = <Object?>[list1_74, list1_74];
+const list1_76 = <Object?>[list1_75, list1_75];
+const list1_77 = <Object?>[list1_76, list1_76];
+const list1_78 = <Object?>[list1_77, list1_77];
+const list1_79 = <Object?>[list1_78, list1_78];
+const list1_80 = <Object?>[list1_79, list1_79];
+const list1_81 = <Object?>[list1_80, list1_80];
+const list1_82 = <Object?>[list1_81, list1_81];
+const list1_83 = <Object?>[list1_82, list1_82];
+const list1_84 = <Object?>[list1_83, list1_83];
+const list1_85 = <Object?>[list1_84, list1_84];
+const list1_86 = <Object?>[list1_85, list1_85];
+const list1_87 = <Object?>[list1_86, list1_86];
+const list1_88 = <Object?>[list1_87, list1_87];
+const list1_89 = <Object?>[list1_88, list1_88];
+const list1_90 = <Object?>[list1_89, list1_89];
+const list1_91 = <Object?>[list1_90, list1_90];
+const list1_92 = <Object?>[list1_91, list1_91];
+const list1_93 = <Object?>[list1_92, list1_92];
+const list1_94 = <Object?>[list1_93, list1_93];
+const list1_95 = <Object?>[list1_94, list1_94];
+const list1_96 = <Object?>[list1_95, list1_95];
+const list1_97 = <Object?>[list1_96, list1_96];
+const list1_98 = <Object?>[list1_97, list1_97];
+const list1_99 = <Object?>[list1_98, list1_98];
+
+const list2_0 = <Object?>[null, null];
+const list2_1 = <Object?>[list2_0, list2_0];
+const list2_2 = <Object?>[list2_1, list2_1];
+const list2_3 = <Object?>[list2_2, list2_2];
+const list2_4 = <Object?>[list2_3, list2_3];
+const list2_5 = <Object?>[list2_4, list2_4];
+const list2_6 = <Object?>[list2_5, list2_5];
+const list2_7 = <Object?>[list2_6, list2_6];
+const list2_8 = <Object?>[list2_7, list2_7];
+const list2_9 = <Object?>[list2_8, list2_8];
+const list2_10 = <Object?>[list2_9, list2_9];
+const list2_11 = <Object?>[list2_10, list2_10];
+const list2_12 = <Object?>[list2_11, list2_11];
+const list2_13 = <Object?>[list2_12, list2_12];
+const list2_14 = <Object?>[list2_13, list2_13];
+const list2_15 = <Object?>[list2_14, list2_14];
+const list2_16 = <Object?>[list2_15, list2_15];
+const list2_17 = <Object?>[list2_16, list2_16];
+const list2_18 = <Object?>[list2_17, list2_17];
+const list2_19 = <Object?>[list2_18, list2_18];
+const list2_20 = <Object?>[list2_19, list2_19];
+const list2_21 = <Object?>[list2_20, list2_20];
+const list2_22 = <Object?>[list2_21, list2_21];
+const list2_23 = <Object?>[list2_22, list2_22];
+const list2_24 = <Object?>[list2_23, list2_23];
+const list2_25 = <Object?>[list2_24, list2_24];
+const list2_26 = <Object?>[list2_25, list2_25];
+const list2_27 = <Object?>[list2_26, list2_26];
+const list2_28 = <Object?>[list2_27, list2_27];
+const list2_29 = <Object?>[list2_28, list2_28];
+const list2_30 = <Object?>[list2_29, list2_29];
+const list2_31 = <Object?>[list2_30, list2_30];
+const list2_32 = <Object?>[list2_31, list2_31];
+const list2_33 = <Object?>[list2_32, list2_32];
+const list2_34 = <Object?>[list2_33, list2_33];
+const list2_35 = <Object?>[list2_34, list2_34];
+const list2_36 = <Object?>[list2_35, list2_35];
+const list2_37 = <Object?>[list2_36, list2_36];
+const list2_38 = <Object?>[list2_37, list2_37];
+const list2_39 = <Object?>[list2_38, list2_38];
+const list2_40 = <Object?>[list2_39, list2_39];
+const list2_41 = <Object?>[list2_40, list2_40];
+const list2_42 = <Object?>[list2_41, list2_41];
+const list2_43 = <Object?>[list2_42, list2_42];
+const list2_44 = <Object?>[list2_43, list2_43];
+const list2_45 = <Object?>[list2_44, list2_44];
+const list2_46 = <Object?>[list2_45, list2_45];
+const list2_47 = <Object?>[list2_46, list2_46];
+const list2_48 = <Object?>[list2_47, list2_47];
+const list2_49 = <Object?>[list2_48, list2_48];
+const list2_50 = <Object?>[list2_49, list2_49];
+const list2_51 = <Object?>[list2_50, list2_50];
+const list2_52 = <Object?>[list2_51, list2_51];
+const list2_53 = <Object?>[list2_52, list2_52];
+const list2_54 = <Object?>[list2_53, list2_53];
+const list2_55 = <Object?>[list2_54, list2_54];
+const list2_56 = <Object?>[list2_55, list2_55];
+const list2_57 = <Object?>[list2_56, list2_56];
+const list2_58 = <Object?>[list2_57, list2_57];
+const list2_59 = <Object?>[list2_58, list2_58];
+const list2_60 = <Object?>[list2_59, list2_59];
+const list2_61 = <Object?>[list2_60, list2_60];
+const list2_62 = <Object?>[list2_61, list2_61];
+const list2_63 = <Object?>[list2_62, list2_62];
+const list2_64 = <Object?>[list2_63, list2_63];
+const list2_65 = <Object?>[list2_64, list2_64];
+const list2_66 = <Object?>[list2_65, list2_65];
+const list2_67 = <Object?>[list2_66, list2_66];
+const list2_68 = <Object?>[list2_67, list2_67];
+const list2_69 = <Object?>[list2_68, list2_68];
+const list2_70 = <Object?>[list2_69, list2_69];
+const list2_71 = <Object?>[list2_70, list2_70];
+const list2_72 = <Object?>[list2_71, list2_71];
+const list2_73 = <Object?>[list2_72, list2_72];
+const list2_74 = <Object?>[list2_73, list2_73];
+const list2_75 = <Object?>[list2_74, list2_74];
+const list2_76 = <Object?>[list2_75, list2_75];
+const list2_77 = <Object?>[list2_76, list2_76];
+const list2_78 = <Object?>[list2_77, list2_77];
+const list2_79 = <Object?>[list2_78, list2_78];
+const list2_80 = <Object?>[list2_79, list2_79];
+const list2_81 = <Object?>[list2_80, list2_80];
+const list2_82 = <Object?>[list2_81, list2_81];
+const list2_83 = <Object?>[list2_82, list2_82];
+const list2_84 = <Object?>[list2_83, list2_83];
+const list2_85 = <Object?>[list2_84, list2_84];
+const list2_86 = <Object?>[list2_85, list2_85];
+const list2_87 = <Object?>[list2_86, list2_86];
+const list2_88 = <Object?>[list2_87, list2_87];
+const list2_89 = <Object?>[list2_88, list2_88];
+const list2_90 = <Object?>[list2_89, list2_89];
+const list2_91 = <Object?>[list2_90, list2_90];
+const list2_92 = <Object?>[list2_91, list2_91];
+const list2_93 = <Object?>[list2_92, list2_92];
+const list2_94 = <Object?>[list2_93, list2_93];
+const list2_95 = <Object?>[list2_94, list2_94];
+const list2_96 = <Object?>[list2_95, list2_95];
+const list2_97 = <Object?>[list2_96, list2_96];
+const list2_98 = <Object?>[list2_97, list2_97];
+const list2_99 = <Object?>[list2_98, list2_98];
+
+confuse(x) {
+  try { throw x; } catch (e) { return e; }
+}
+
+main() {
+  if (!identical(confuse(list1_99), confuse(list2_99))) {
+    throw new Exception("list1_99 !== list2_99");
+  }
+}

tests/language/canonicalize/hashing_memoize_instance_test.dart

@@ -0,0 +1,224 @@
+// Copyright (c) 2019, 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.
+
+// If canonicalization uses deep structural hashing without memoizing, this
+// will exhibit superlinear time.
+
+class Box {
+  final Object? content1;
+  final Object? content2;
+  const Box(this.content1, this.content2);
+}
+
+const box1_0 = Box(null, null);
+const box1_1 = Box(box1_0, box1_0);
+const box1_2 = Box(box1_1, box1_1);
+const box1_3 = Box(box1_2, box1_2);
+const box1_4 = Box(box1_3, box1_3);
+const box1_5 = Box(box1_4, box1_4);
+const box1_6 = Box(box1_5, box1_5);
+const box1_7 = Box(box1_6, box1_6);
+const box1_8 = Box(box1_7, box1_7);
+const box1_9 = Box(box1_8, box1_8);
+const box1_10 = Box(box1_9, box1_9);
+const box1_11 = Box(box1_10, box1_10);
+const box1_12 = Box(box1_11, box1_11);
+const box1_13 = Box(box1_12, box1_12);
+const box1_14 = Box(box1_13, box1_13);
+const box1_15 = Box(box1_14, box1_14);
+const box1_16 = Box(box1_15, box1_15);
+const box1_17 = Box(box1_16, box1_16);
+const box1_18 = Box(box1_17, box1_17);
+const box1_19 = Box(box1_18, box1_18);
+const box1_20 = Box(box1_19, box1_19);
+const box1_21 = Box(box1_20, box1_20);
+const box1_22 = Box(box1_21, box1_21);
+const box1_23 = Box(box1_22, box1_22);
+const box1_24 = Box(box1_23, box1_23);
+const box1_25 = Box(box1_24, box1_24);
+const box1_26 = Box(box1_25, box1_25);
+const box1_27 = Box(box1_26, box1_26);
+const box1_28 = Box(box1_27, box1_27);
+const box1_29 = Box(box1_28, box1_28);
+const box1_30 = Box(box1_29, box1_29);
+const box1_31 = Box(box1_30, box1_30);
+const box1_32 = Box(box1_31, box1_31);
+const box1_33 = Box(box1_32, box1_32);
+const box1_34 = Box(box1_33, box1_33);
+const box1_35 = Box(box1_34, box1_34);
+const box1_36 = Box(box1_35, box1_35);
+const box1_37 = Box(box1_36, box1_36);
+const box1_38 = Box(box1_37, box1_37);
+const box1_39 = Box(box1_38, box1_38);
+const box1_40 = Box(box1_39, box1_39);
+const box1_41 = Box(box1_40, box1_40);
+const box1_42 = Box(box1_41, box1_41);
+const box1_43 = Box(box1_42, box1_42);
+const box1_44 = Box(box1_43, box1_43);
+const box1_45 = Box(box1_44, box1_44);
+const box1_46 = Box(box1_45, box1_45);
+const box1_47 = Box(box1_46, box1_46);
+const box1_48 = Box(box1_47, box1_47);
+const box1_49 = Box(box1_48, box1_48);
+const box1_50 = Box(box1_49, box1_49);
+const box1_51 = Box(box1_50, box1_50);
+const box1_52 = Box(box1_51, box1_51);
+const box1_53 = Box(box1_52, box1_52);
+const box1_54 = Box(box1_53, box1_53);
+const box1_55 = Box(box1_54, box1_54);
+const box1_56 = Box(box1_55, box1_55);
+const box1_57 = Box(box1_56, box1_56);
+const box1_58 = Box(box1_57, box1_57);
+const box1_59 = Box(box1_58, box1_58);
+const box1_60 = Box(box1_59, box1_59);
+const box1_61 = Box(box1_60, box1_60);
+const box1_62 = Box(box1_61, box1_61);
+const box1_63 = Box(box1_62, box1_62);
+const box1_64 = Box(box1_63, box1_63);
+const box1_65 = Box(box1_64, box1_64);
+const box1_66 = Box(box1_65, box1_65);
+const box1_67 = Box(box1_66, box1_66);
+const box1_68 = Box(box1_67, box1_67);
+const box1_69 = Box(box1_68, box1_68);
+const box1_70 = Box(box1_69, box1_69);
+const box1_71 = Box(box1_70, box1_70);
+const box1_72 = Box(box1_71, box1_71);
+const box1_73 = Box(box1_72, box1_72);
+const box1_74 = Box(box1_73, box1_73);
+const box1_75 = Box(box1_74, box1_74);
+const box1_76 = Box(box1_75, box1_75);
+const box1_77 = Box(box1_76, box1_76);
+const box1_78 = Box(box1_77, box1_77);
+const box1_79 = Box(box1_78, box1_78);
+const box1_80 = Box(box1_79, box1_79);
+const box1_81 = Box(box1_80, box1_80);
+const box1_82 = Box(box1_81, box1_81);
+const box1_83 = Box(box1_82, box1_82);
+const box1_84 = Box(box1_83, box1_83);
+const box1_85 = Box(box1_84, box1_84);
+const box1_86 = Box(box1_85, box1_85);
+const box1_87 = Box(box1_86, box1_86);
+const box1_88 = Box(box1_87, box1_87);
+const box1_89 = Box(box1_88, box1_88);
+const box1_90 = Box(box1_89, box1_89);
+const box1_91 = Box(box1_90, box1_90);
+const box1_92 = Box(box1_91, box1_91);
+const box1_93 = Box(box1_92, box1_92);
+const box1_94 = Box(box1_93, box1_93);
+const box1_95 = Box(box1_94, box1_94);
+const box1_96 = Box(box1_95, box1_95);
+const box1_97 = Box(box1_96, box1_96);
+const box1_98 = Box(box1_97, box1_97);
+const box1_99 = Box(box1_98, box1_98);
+
+const box2_0 = Box(null, null);
+const box2_1 = Box(box2_0, box2_0);
+const box2_2 = Box(box2_1, box2_1);
+const box2_3 = Box(box2_2, box2_2);
+const box2_4 = Box(box2_3, box2_3);
+const box2_5 = Box(box2_4, box2_4);
+const box2_6 = Box(box2_5, box2_5);
+const box2_7 = Box(box2_6, box2_6);
+const box2_8 = Box(box2_7, box2_7);
+const box2_9 = Box(box2_8, box2_8);
+const box2_10 = Box(box2_9, box2_9);
+const box2_11 = Box(box2_10, box2_10);
+const box2_12 = Box(box2_11, box2_11);
+const box2_13 = Box(box2_12, box2_12);
+const box2_14 = Box(box2_13, box2_13);
+const box2_15 = Box(box2_14, box2_14);
+const box2_16 = Box(box2_15, box2_15);
+const box2_17 = Box(box2_16, box2_16);
+const box2_18 = Box(box2_17, box2_17);
+const box2_19 = Box(box2_18, box2_18);
+const box2_20 = Box(box2_19, box2_19);
+const box2_21 = Box(box2_20, box2_20);
+const box2_22 = Box(box2_21, box2_21);
+const box2_23 = Box(box2_22, box2_22);
+const box2_24 = Box(box2_23, box2_23);
+const box2_25 = Box(box2_24, box2_24);
+const box2_26 = Box(box2_25, box2_25);
+const box2_27 = Box(box2_26, box2_26);
+const box2_28 = Box(box2_27, box2_27);
+const box2_29 = Box(box2_28, box2_28);
+const box2_30 = Box(box2_29, box2_29);
+const box2_31 = Box(box2_30, box2_30);
+const box2_32 = Box(box2_31, box2_31);
+const box2_33 = Box(box2_32, box2_32);
+const box2_34 = Box(box2_33, box2_33);
+const box2_35 = Box(box2_34, box2_34);
+const box2_36 = Box(box2_35, box2_35);
+const box2_37 = Box(box2_36, box2_36);
+const box2_38 = Box(box2_37, box2_37);
+const box2_39 = Box(box2_38, box2_38);
+const box2_40 = Box(box2_39, box2_39);
+const box2_41 = Box(box2_40, box2_40);
+const box2_42 = Box(box2_41, box2_41);
+const box2_43 = Box(box2_42, box2_42);
+const box2_44 = Box(box2_43, box2_43);
+const box2_45 = Box(box2_44, box2_44);
+const box2_46 = Box(box2_45, box2_45);
+const box2_47 = Box(box2_46, box2_46);
+const box2_48 = Box(box2_47, box2_47);
+const box2_49 = Box(box2_48, box2_48);
+const box2_50 = Box(box2_49, box2_49);
+const box2_51 = Box(box2_50, box2_50);
+const box2_52 = Box(box2_51, box2_51);
+const box2_53 = Box(box2_52, box2_52);
+const box2_54 = Box(box2_53, box2_53);
+const box2_55 = Box(box2_54, box2_54);
+const box2_56 = Box(box2_55, box2_55);
+const box2_57 = Box(box2_56, box2_56);
+const box2_58 = Box(box2_57, box2_57);
+const box2_59 = Box(box2_58, box2_58);
+const box2_60 = Box(box2_59, box2_59);
+const box2_61 = Box(box2_60, box2_60);
+const box2_62 = Box(box2_61, box2_61);
+const box2_63 = Box(box2_62, box2_62);
+const box2_64 = Box(box2_63, box2_63);
+const box2_65 = Box(box2_64, box2_64);
+const box2_66 = Box(box2_65, box2_65);
+const box2_67 = Box(box2_66, box2_66);
+const box2_68 = Box(box2_67, box2_67);
+const box2_69 = Box(box2_68, box2_68);
+const box2_70 = Box(box2_69, box2_69);
+const box2_71 = Box(box2_70, box2_70);
+const box2_72 = Box(box2_71, box2_71);
+const box2_73 = Box(box2_72, box2_72);
+const box2_74 = Box(box2_73, box2_73);
+const box2_75 = Box(box2_74, box2_74);
+const box2_76 = Box(box2_75, box2_75);
+const box2_77 = Box(box2_76, box2_76);
+const box2_78 = Box(box2_77, box2_77);
+const box2_79 = Box(box2_78, box2_78);
+const box2_80 = Box(box2_79, box2_79);
+const box2_81 = Box(box2_80, box2_80);
+const box2_82 = Box(box2_81, box2_81);
+const box2_83 = Box(box2_82, box2_82);
+const box2_84 = Box(box2_83, box2_83);
+const box2_85 = Box(box2_84, box2_84);
+const box2_86 = Box(box2_85, box2_85);
+const box2_87 = Box(box2_86, box2_86);
+const box2_88 = Box(box2_87, box2_87);
+const box2_89 = Box(box2_88, box2_88);
+const box2_90 = Box(box2_89, box2_89);
+const box2_91 = Box(box2_90, box2_90);
+const box2_92 = Box(box2_91, box2_91);
+const box2_93 = Box(box2_92, box2_92);
+const box2_94 = Box(box2_93, box2_93);
+const box2_95 = Box(box2_94, box2_94);
+const box2_96 = Box(box2_95, box2_95);
+const box2_97 = Box(box2_96, box2_96);
+const box2_98 = Box(box2_97, box2_97);
+const box2_99 = Box(box2_98, box2_98);
+
+confuse(x) {
+  try { throw x; } catch (e) { return e; }
+}
+
+main() {
+  if (!identical(confuse(box1_99), confuse(box2_99))) {
+    throw new Exception("box1_99 !== box2_99");
+  }
+}