[dart:js_interop] Add JS types for Symbol/BigInt

Adds JSSymbol and JSBigInt and erases to either their respective
interceptor types in the JS backends or JSValue in dart2wasm.

CoreLibraryReviewExempt: Backend-specific library.
Change-Id: Ib2c70d22a70c6308733cd170b91eafa8ec3b3aeb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/321749
Reviewed-by: Sigmund Cherem <sigmund@google.com>

CHANGELOG.md

@@ -90,7 +90,9 @@
   interceptor and should not be used with `package:js` classes. These types were
   being intercepted with the assumption that they are a subtype of JavaScript's
   `Object`, but this is incorrect. This lead to erroneous behavior when using
-  these types as Dart `Object`s. See [#53106][] for more details.
+  these types as Dart `Object`s. See [#53106][] for more details. Use
+  `dart:js_interop`'s `JSSymbol` and `JSBigInt` with extension types to interop
+  with these types.
 
 #### Dart2js
 
@@ -99,7 +101,9 @@
   interceptor and should not be used with `package:js` classes. These types were
   being intercepted with the assumption that they are a subtype of JavaScript's
   `Object`, but this is incorrect. This lead to erroneous behavior when using
-  these types as Dart `Object`s. See [#53106][] for more details.
+  these types as Dart `Object`s. See [#53106][] for more details. Use
+  `dart:js_interop`'s `JSSymbol` and `JSBigInt` with extension types to interop
+  with these types.
 
 [#53106]: https://github.com/dart-lang/sdk/issues/53106
 

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

@@ -101,6 +101,14 @@ InterfaceType eraseStaticInteropTypesForJSCompilers(
         erasedClass =
             coreTypes.index.getClass('dart:_interceptors', 'JSObject');
         break;
+      case 'JSSymbol':
+        erasedClass =
+            coreTypes.index.getClass('dart:_interceptors', 'JavaScriptSymbol');
+        break;
+      case 'JSBigInt':
+        erasedClass =
+            coreTypes.index.getClass('dart:_interceptors', 'JavaScriptBigInt');
+        break;
       default:
         throw 'Unimplemented `dart:_js_types`: $className';
     }

pkg/compiler/test/impact/data/jsinterop.dart

@@ -35,6 +35,7 @@ class JsInteropClass {
     native:JSAny,
     native:JSArray,
     native:JSArrayBuffer,
+    native:JSBigInt,
     native:JSBoolean,
     native:JSBoxedDartObject,
     native:JSDataView,
@@ -49,6 +50,7 @@ class JsInteropClass {
     native:JSObject,
     native:JSPromise,
     native:JSString,
+    native:JSSymbol,
     native:JSTypedArray,
     native:JSUint16Array,
     native:JSUint32Array,

pkg/compiler/test/impact/data/jsinterop_setter1.dart

@@ -58,6 +58,7 @@ import 'package:js/js.dart';
   native:JSAny,
   native:JSArray,
   native:JSArrayBuffer,
+  native:JSBigInt,
   native:JSBoolean,
   native:JSBoxedDartObject,
   native:JSDataView,
@@ -72,6 +73,7 @@ import 'package:js/js.dart';
   native:JSObject,
   native:JSPromise,
   native:JSString,
+  native:JSSymbol,
   native:JSTypedArray,
   native:JSUint16Array,
   native:JSUint32Array,

pkg/compiler/test/impact/data/jsinterop_setter2.dart

@@ -65,6 +65,7 @@ import 'package:js/js.dart';
   native:JSAny,
   native:JSArray,
   native:JSArrayBuffer,
+  native:JSBigInt,
   native:JSBoolean,
   native:JSBoxedDartObject,
   native:JSDataView,
@@ -79,6 +80,7 @@ import 'package:js/js.dart';
   native:JSObject,
   native:JSPromise,
   native:JSString,
+  native:JSSymbol,
   native:JSTypedArray,
   native:JSUint16Array,
   native:JSUint32Array,

sdk/lib/_internal/js_shared/lib/js_types.dart

@@ -51,6 +51,7 @@ class JSExportedDartFunction implements JSFunction {}
 @staticInterop
 class JSArray implements JSObject {
   external factory JSArray();
+  // TODO(srujzs): Should we make this an `int`?
   external factory JSArray.withLength(JSNumber length);
 }
 
@@ -118,6 +119,14 @@ class JSBoolean implements JSAny {}
 @staticInterop
 class JSString implements JSAny {}
 
+@JS()
+@staticInterop
+class JSSymbol implements JSAny {}
+
+@JS()
+@staticInterop
+class JSBigInt implements JSAny {}
+
 /// [JSVoid] is just a typedef for [void]. While we could just use
 /// `JSUndefined`, in the future we may be able to use this to elide `return`s
 /// in JS trampolines.

sdk/lib/_internal/wasm/lib/js_types.dart

@@ -99,6 +99,7 @@ class JSPromise implements JSObject {}
 @staticInterop
 class JSArray implements JSObject {
   external factory JSArray();
+  // TODO(srujzs): Should we make this an `int`?
   external factory JSArray.withLength(JSNumber length);
 }
 
@@ -166,6 +167,14 @@ class JSBoolean implements JSAny {}
 @staticInterop
 class JSString implements JSAny {}
 
+@JS()
+@staticInterop
+class JSSymbol implements JSAny {}
+
+@JS()
+@staticInterop
+class JSBigInt implements JSAny {}
+
 /// [JSVoid] is just a typedef for [void]. While we could just use
 /// `JSUndefined`, in the future we may be able to use this to elide `return`s
 /// in JS trampolines.

sdk/lib/js_interop/js_interop.dart

@@ -136,6 +136,12 @@ typedef JSBoolean = js_types.JSBoolean;
 /// The type of JS strings, [JSString] <: [JSAny].
 typedef JSString = js_types.JSString;
 
+/// The type of JS Symbols, [JSSymbol] <: [JSAny].
+typedef JSSymbol = js_types.JSSymbol;
+
+/// The type of JS BigInts, [JSBigInt] <: [JSAny].
+typedef JSBigInt = js_types.JSBigInt;
+
 /// A getter to retrieve the global context that is used in static interop
 /// lowering.
 external JSObject get globalContext;

tests/lib/js/static_interop_test/js_types_test.dart

@@ -88,6 +88,28 @@ external JSBoolean boo;
 @JS()
 external JSString str;
 
+@JS()
+external JSSymbol symbol;
+
+@JS('Symbol')
+external JSSymbol createSymbol(String value);
+
+extension on JSSymbol {
+  @JS('toString')
+  external String toStringExternal();
+}
+
+@JS()
+external JSBigInt bigInt;
+
+@JS('BigInt')
+external JSBigInt createBigInt(String value);
+
+extension on JSBigInt {
+  @JS('toString')
+  external String toStringExternal();
+}
+
 @JS()
 external JSAny? nullAny;
 
@@ -240,6 +262,16 @@ void syncTests() {
   String dartStr = str.toDart;
   expect(dartStr, 'foo');
 
+  // [JSSymbol]
+  symbol = createSymbol('foo');
+  expect(symbol is JSSymbol, true);
+  expect(symbol.toStringExternal(), 'Symbol(foo)');
+
+  // [JSBigInt]
+  bigInt = createBigInt('9876543210000000000000123456789');
+  expect(bigInt is JSBigInt, true);
+  expect(bigInt.toStringExternal(), '9876543210000000000000123456789');
+
   // null and undefined can flow into `JSAny?`.
   // TODO(joshualitt): Fix tests when `JSNull` and `JSUndefined` are no longer
   // conflated.