Add external extension fields, getters, and setters.

CFE transformation to add a function body for external fields,
getters, and setters, routing to the relevant js_util
getProperty and setProperty optimized calls.

Change-Id: Ia3d0f05fda50f20d217c0a67e0fd636bb774000b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/213600
Commit-Queue: Riley Porter <rileyporter@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Srujan Gaddam <srujzs@google.com>

pkg/_js_interop_checks/lib/src/transformations/js_util_optimizer.dart

@@ -2,11 +2,14 @@
 // 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:front_end/src/api_unstable/dart2js.dart' as api;
 import 'package:kernel/ast.dart';
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:kernel/type_environment.dart';
 
+import '../js_interop.dart' show getJSName;
+
 /// Replaces js_util methods with inline calls to foreign_helper JS which
 /// emits the code as a JavaScript code fragment.
 class JsUtilOptimizer extends Transformer {
@@ -82,6 +85,79 @@ class JsUtilOptimizer extends Transformer {
     return node;
   }
 
+  @override
+  visitProcedure(Procedure node) {
+    _staticTypeContext.enterMember(node);
+    // Getters, setters, and fields declared as `static` will be skipped,
+    // because they do not have a node.kind of ProcedureKind.Method.
+    if (node.isExternal &&
+        node.isExtensionMember &&
+        node.kind == ProcedureKind.Method) {
+      var transformedBody;
+      if (api.getExtensionMemberKind(node) == ProcedureKind.Getter) {
+        transformedBody = _getExternalGetterBody(node);
+      } else if (api.getExtensionMemberKind(node) == ProcedureKind.Setter) {
+        transformedBody = _getExternalSetterBody(node);
+      }
+      // TODO(rileyporter): Add transformation for external extension methods,
+      // static members, and any operators we decide to support.
+      if (transformedBody != null) {
+        node.function.body = transformedBody;
+        node.isExternal = false;
+      }
+    } else {
+      node.transformChildren(this);
+    }
+    _staticTypeContext.leaveMember(node);
+    return node;
+  }
+
+  /// Returns a new function body for the given [node] external getter.
+  ///
+  /// The new function body will call the optimized version of
+  /// `js_util.getProperty` for the given external getter.
+  ReturnStatement _getExternalGetterBody(Procedure node) {
+    var function = node.function;
+    assert(function.positionalParameters.length == 1);
+    var getPropertyInvocation = StaticInvocation(
+        _getPropertyTarget,
+        Arguments([
+          VariableGet(function.positionalParameters.first),
+          StringLiteral(_getMemberName(node))
+        ]))
+      ..fileOffset = node.fileOffset;
+    return ReturnStatement(AsExpression(
+        _lowerGetProperty(getPropertyInvocation), function.returnType));
+  }
+
+  /// Returns a new function body for the given [node] external setter.
+  ///
+  /// The new function body will call the optimized version of
+  /// `js_util.setProperty` for the given external setter.
+  ReturnStatement _getExternalSetterBody(Procedure node) {
+    var function = node.function;
+    assert(function.positionalParameters.length == 2);
+    var setPropertyInvocation = StaticInvocation(
+        _setPropertyTarget,
+        Arguments([
+          VariableGet(function.positionalParameters.first),
+          StringLiteral(_getMemberName(node)),
+          VariableGet(function.positionalParameters.last)
+        ]))
+      ..fileOffset = node.fileOffset;
+    return ReturnStatement(AsExpression(
+        _lowerSetProperty(setPropertyInvocation), function.returnType));
+  }
+
+  /// Returns the member name, either from the `@JS` annotation if non-empty,
+  /// or parsed from CFE generated node name.
+  String _getMemberName(Procedure node) {
+    var jsAnnotationName = getJSName(node);
+    return jsAnnotationName.isNotEmpty
+        ? jsAnnotationName
+        : node.name.text.substring(node.name.text.indexOf('#') + 1);
+  }
+
   /// Replaces js_util method calls with optimization when possible.
   ///
   /// Lowers `getProperty` for any argument type straight to JS fragment call.

pkg/_js_interop_checks/pubspec.yaml

@@ -8,5 +8,7 @@ environment:
 dependencies:
   _fe_analyzer_shared:
     path: ../_fe_analyzer_shared
+  front_end:
+    path: ../front_end
   kernel:
     path: ../kernel

pkg/compiler/lib/src/kernel/dart2js_target.dart

@@ -144,14 +144,14 @@ class Dart2jsTarget extends Target {
     var nativeClasses = JsInteropChecks.getNativeClasses(component);
     var jsUtilOptimizer = JsUtilOptimizer(coreTypes, hierarchy);
     for (var library in libraries) {
-      // TODO (rileyporter): Merge js_util optimizations with other lowerings
-      // in the single pass in `transformations/lowering.dart`.
-      jsUtilOptimizer.visitLibrary(library);
       JsInteropChecks(
               coreTypes,
               diagnosticReporter as DiagnosticReporter<Message, LocatedMessage>,
               nativeClasses)
           .visitLibrary(library);
+      // TODO (rileyporter): Merge js_util optimizations with other lowerings
+      // in the single pass in `transformations/lowering.dart`.
+      jsUtilOptimizer.visitLibrary(library);
     }
     lowering.transformLibraries(libraries, coreTypes, hierarchy, options);
     logger?.call("Lowering transformations performed");

pkg/dev_compiler/lib/src/kernel/target.dart

@@ -160,12 +160,12 @@ class DevCompilerTarget extends Target {
     var jsUtilOptimizer = JsUtilOptimizer(coreTypes, hierarchy);
     for (var library in libraries) {
       _CovarianceTransformer(library).transform();
-      jsUtilOptimizer.visitLibrary(library);
       JsInteropChecks(
               coreTypes,
               diagnosticReporter as DiagnosticReporter<Message, LocatedMessage>,
               _nativeClasses!)
           .visitLibrary(library);
+      jsUtilOptimizer.visitLibrary(library);
     }
   }
 

tests/lib/js/external_extension_members_test.dart

@@ -0,0 +1,107 @@
+// Copyright (c) 2021, 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.
+
+// Tests behavior of external extension members, which are routed to js_util
+// calls by a CFE transformation.
+
+@JS()
+library external_extension_members_test;
+
+import 'package:js/js.dart';
+import 'package:js/js_util.dart' as js_util;
+import 'package:expect/minitest.dart';
+
+@JS()
+external void eval(String code);
+
+@JS()
+class Foo {
+  external Foo(int a);
+}
+
+extension FooExt on Foo {
+  external var field;
+  external final finalField;
+  @JS('fieldAnnotation')
+  external var annotatedField;
+
+  external get getter;
+  @JS('getterAnnotation')
+  external get annotatedGetter;
+
+  external set setter(_);
+  @JS('setterAnnotation')
+  external set annotatedSetter(_);
+}
+
+@JS('module.Bar')
+class Bar {
+  external Bar(int a);
+}
+
+extension BarExt on Bar {
+  @JS('field')
+  external var barField;
+}
+
+void main() {
+  eval(r"""
+    function Foo(a) {
+      this.field = a;
+      this.fieldAnnotation = a;
+      this.finalField = a;
+
+      this.getter = a;
+      this.getterAnnotation = a;
+    }
+
+    var module = {Bar: Foo};
+    """);
+
+  test('fields', () {
+    var foo = Foo(42);
+    // field getters
+    expect(foo.field, equals(42));
+    expect(foo.finalField, equals(42));
+    expect(foo.annotatedField, equals(42));
+
+    // field setters
+    foo.field = 'squid';
+    expect(foo.field, equals('squid'));
+
+    foo.annotatedField = 'octopus';
+    expect(foo.annotatedField, equals('octopus'));
+    js_util.setProperty(foo, 'fieldAnnotation', 'clownfish');
+    expect(foo.annotatedField, equals('clownfish'));
+  });
+
+  test('getters', () {
+    var foo = Foo(42);
+    expect(foo.getter, equals(42));
+    expect(foo.annotatedGetter, equals(42));
+
+    js_util.setProperty(foo, 'getterAnnotation', 'eel');
+    expect(foo.annotatedGetter, equals('eel'));
+  });
+
+  test('setters', () {
+    var foo = Foo(42);
+    foo.setter = 'starfish';
+    expect(js_util.getProperty(foo, 'setter'), equals('starfish'));
+
+    foo.annotatedSetter = 'whale';
+    expect(js_util.getProperty(foo, 'setterAnnotation'), equals('whale'));
+  });
+
+  test('module class', () {
+    var bar = Bar(5);
+    expect(js_util.getProperty(bar, 'fieldAnnotation'), equals(5));
+    expect(bar.barField, equals(5));
+    expect(js_util.getProperty(bar, 'field'), equals(5));
+
+    bar.barField = 10;
+    expect(js_util.getProperty(bar, 'fieldAnnotation'), equals(5));
+    expect(js_util.getProperty(bar, 'field'), equals(10));
+  });
+}

tests/lib_2/js/external_extension_members_test.dart

@@ -0,0 +1,89 @@
+// Copyright (c) 2021, 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.
+
+// @dart = 2.9
+
+// Tests behavior of external extension members, which are routed to js_util
+// calls by a CFE transformation.
+
+@JS()
+library external_extension_members_test;
+
+import 'package:js/js.dart';
+import 'package:js/js_util.dart' as js_util;
+import 'package:expect/minitest.dart';
+
+@JS()
+external void eval(String code);
+
+@JS()
+class Foo {
+  external Foo(int a);
+}
+
+extension FooExt on Foo {
+  external get getter;
+  @JS('getterAnnotation')
+  external get annotatedGetter;
+
+  external set setter(_);
+  @JS('setterAnnotation')
+  external set annotatedSetter(_);
+}
+
+@JS('module.Bar')
+class Bar {
+  external Bar(int a);
+}
+
+extension BarExt on Bar {
+  @JS('field')
+  external get barFieldGetter;
+  @JS('field')
+  external set barFieldSetter(_);
+}
+
+void main() {
+  eval(r"""
+    function Foo(a) {
+      this.field = a;
+      this.fieldAnnotation = a;
+      this.finalField = a;
+
+      this.getter = a;
+      this.getterAnnotation = a;
+    }
+
+    var module = {Bar: Foo};
+    """);
+
+  test('getters', () {
+    var foo = Foo(42);
+    expect(foo.getter, equals(42));
+    expect(foo.annotatedGetter, equals(42));
+
+    js_util.setProperty(foo, 'getterAnnotation', 'eel');
+    expect(foo.annotatedGetter, equals('eel'));
+  });
+
+  test('setters', () {
+    var foo = Foo(42);
+    foo.setter = 'starfish';
+    expect(js_util.getProperty(foo, 'setter'), equals('starfish'));
+
+    foo.annotatedSetter = 'whale';
+    expect(js_util.getProperty(foo, 'setterAnnotation'), equals('whale'));
+  });
+
+  test('module class', () {
+    var bar = Bar(5);
+    expect(js_util.getProperty(bar, 'fieldAnnotation'), equals(5));
+    expect(bar.barFieldGetter, equals(5));
+    expect(js_util.getProperty(bar, 'field'), equals(5));
+
+    bar.barFieldSetter = 10;
+    expect(js_util.getProperty(bar, 'fieldAnnotation'), equals(5));
+    expect(js_util.getProperty(bar, 'field'), equals(10));
+  });
+}