[web] Move Variance to js_shared/lib/ for shared use.

Moving variance to `js_shared/lib/variance.dart` so we can use the same synced indices when marking variance in both dart2js and ddc.

This avoids needing to sync multiple data structures that all represent variance.

Bug: #54367

Change-Id: Ia6fda84decd43374c08ed3bd0d0b240071310d9a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/341840
Reviewed-by: Mayank Patke <[email protected]>
Commit-Queue: Kallen Tu <[email protected]>
Reviewed-by: Nicholas Shahan <[email protected]>

Author: kallentu

pkg/compiler/lib/src/common/elements.dart

@@ -2,6 +2,8 @@
 // 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:js_shared/variance.dart';
+
 import '../common.dart';
 import '../constants/constant_system.dart' as constant_system;
 import '../constants/values.dart';

pkg/compiler/lib/src/elements/entities.dart

@@ -227,10 +227,6 @@ class AsyncMarker {
   int get index => values.indexOf(this);
 }
 
-/// Values for variance annotations.
-/// This needs to be kept in sync with values of `Variance` in `dart:_rti`.
-enum Variance { legacyCovariant, covariant, contravariant, invariant }
-
 /// Stripped down super interface for constructor like entities.
 ///
 /// Currently only [ConstructorElement] but later also kernel based Dart

pkg/compiler/lib/src/elements/types.dart

@@ -2,6 +2,8 @@
 // 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:js_shared/variance.dart';
+
 import '../common/elements.dart' show CommonElements;
 import '../common/names.dart';
 import '../options.dart';

pkg/compiler/lib/src/inferrer/powersets/powerset_bits.dart

@@ -2,6 +2,8 @@
 // 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:js_shared/variance.dart';
+
 import '../../common/elements.dart' show CommonElements;
 import '../../constants/values.dart';
 import '../../elements/entities.dart';

pkg/compiler/lib/src/inferrer/typemasks/masks.dart

@@ -4,6 +4,7 @@
 
 library masks;
 
+import 'package:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 
 import '../../common.dart';

pkg/compiler/lib/src/ir/element_map.dart

@@ -2,6 +2,7 @@
 // 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:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/core_types.dart' as ir;
 

pkg/compiler/lib/src/ir/types.dart

@@ -2,6 +2,8 @@
 // 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:js_shared/variance.dart';
+
 import '../common/elements.dart';
 import '../elements/entities.dart';
 import '../elements/types.dart';

pkg/compiler/lib/src/ir/util.dart

@@ -2,10 +2,11 @@
 // 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:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
-import '../elements/entities.dart' show AsyncMarker, MemberEntity, Variance;
+import '../elements/entities.dart' show AsyncMarker, MemberEntity;
 import '../universe/record_shape.dart';
 
 /// Returns a textual representation of [node] that include the runtime type and

pkg/compiler/lib/src/js_backend/runtime_types_new.dart

@@ -5,6 +5,7 @@
 library js_backend.runtime_types_new;
 
 import 'package:js_shared/synced/recipe_syntax.dart';
+import 'package:js_shared/variance.dart';
 
 import '../common/elements.dart' show CommonElements, JCommonElements;
 import '../elements/entities.dart';

pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart

@@ -35,6 +35,7 @@ import 'package:js_shared/synced/embedded_names.dart'
         RTI_UNIVERSE,
         RtiUniverseFieldNames,
         TYPES;
+import 'package:js_shared/variance.dart';
 
 import 'package:js_ast/src/precedence.dart' as js_precedence;
 

pkg/compiler/lib/src/js_model/closure.dart

@@ -2,6 +2,7 @@
 // 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:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 
 import '../closure.dart';

pkg/compiler/lib/src/js_model/element_map_impl.dart

@@ -2,6 +2,7 @@
 // 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:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/class_hierarchy.dart' as ir;
 import 'package:kernel/core_types.dart' as ir;

pkg/compiler/lib/src/js_model/env.dart

@@ -4,6 +4,7 @@
 
 library dart2js.js_model.env;
 
+import 'package:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 
 import '../constants/values.dart';

pkg/compiler/lib/src/js_model/records.dart

@@ -29,6 +29,8 @@
 /// (Specialization classes have not yet been implemented).
 library dart2js.js_model.records;
 
+import 'package:js_shared/variance.dart';
+
 import '../common.dart';
 import '../constants/values.dart' show ConstantValue;
 import '../elements/entities.dart';

pkg/compiler/lib/src/kernel/element_map_impl.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:js_shared/synced/embedded_names.dart' show JsGetName;
+import 'package:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/class_hierarchy.dart' as ir;
 import 'package:kernel/core_types.dart' as ir;

pkg/compiler/lib/src/kernel/env.dart

@@ -4,6 +4,7 @@
 
 library dart2js.kernel.env;
 
+import 'package:js_shared/variance.dart';
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/type_environment.dart' as ir;
 import 'package:collection/collection.dart' show mergeSort; // a stable sort.

pkg/js_shared/lib/variance.dart

@@ -0,0 +1,7 @@
+// Copyright (c) 2023, 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.
+
+/// Types of variances for type parameters.
+/// This needs to be kept in sync with values of `Variance` in `dart:_rti`.
+enum Variance { legacyCovariant, covariant, contravariant, invariant }

sdk/lib/_internal/js_shared/lib/rti.dart

@@ -3240,7 +3240,8 @@ class TypeRule {
       JS('', '#.#', rule, supertype);
 }
 
-// This needs to be kept in sync with `Variance` in `entities.dart`.
+// This needs to be kept in sync with `Variance` in
+// `pkg/js_shared/lib/variance.dart`.
 class Variance {
   // TODO(fishythefish): Try bitmask representation.
   static const int legacyCovariant = 0;