[dart2js] Add subtyping for identical interface names without explicit type rule.

Change-Id: I0db1ff88e6fcb6a5e3f7615aa588afb473a77a16
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106820
Commit-Queue: Mayank Patke <[email protected]>
Reviewed-by: Stephen Adams <[email protected]>

Author: fishythefish

sdk/lib/_internal/js_runtime/lib/rti.dart

@@ -984,7 +984,19 @@ bool _isSubtype(universe, Rti s, var sEnv, Rti t, var tEnv) {
   assert(Rti._getKind(t) == Rti.kindInterface);
   String sName = Rti._getInterfaceName(s);
   String tName = Rti._getInterfaceName(t);
-  // TODO(fishythefish): Handle identical names.
+
+  if (sName == tName) {
+    var sArgs = Rti._getInterfaceTypeArguments(s);
+    var tArgs = Rti._getInterfaceTypeArguments(t);
+    int length = _Utils.arrayLength(sArgs);
+    assert(length == _Utils.arrayLength(tArgs));
+    for (int i = 0; i < length; i++) {
+      Rti sArg = _castToRti(_Utils.arrayAt(sArgs, i));
+      Rti tArg = _castToRti(_Utils.arrayAt(tArgs, i));
+      if (!_isSubtype(universe, sArg, sEnv, tArg, tEnv)) return false;
+    }
+    return true;
+  }
 
   // TODO(fishythefish): Should we recursively attempt to find supertypes?
   var rule = _Universe.findRule(universe, sName);
@@ -998,7 +1010,7 @@ bool _isSubtype(universe, Rti s, var sEnv, Rti t, var tEnv) {
     String recipe = _Utils.arrayAt(supertypeArgs, i);
     Rti supertypeArg = _Universe.evalInEnvironment(universe, s, recipe);
     Rti tArg = _castToRti(_Utils.arrayAt(tArgs, i));
-    if (!isSubtype(universe, supertypeArg, tArg)) return false;
+    if (!_isSubtype(universe, supertypeArg, sEnv, tArg, tEnv)) return false;
   }
 
   return true;

tests/compiler/dart2js_extra/rti/subtype_test.dart

@@ -13,8 +13,7 @@ const typeRulesJson = r'''
   "CodeUnits": {
     "List": ["int"],
     "Iterable": ["int"]
-  },
-  "Object": {"Object": []}
+  }
 }
 ''';
 final typeRules = JS('=Object', 'JSON.parse(#)', typeRulesJson);
@@ -29,8 +28,26 @@ main() {
 void runTests() {
   strictSubtype('List<CodeUnits>', 'Iterable<List<int>>');
   strictSubtype('CodeUnits', 'Iterable<num>');
+  strictSubtype('Iterable<int>', 'Iterable<num>');
   unrelated('int', 'CodeUnits');
+  equivalent('double', 'double');
   equivalent('Object', 'Object');
+  equivalent('@', '@');
+  equivalent('~', '~');
+  equivalent('1&', '1&');
+  equivalent('List<int>', 'List<int>');
+  //equivalent('Object', '@');
+  //equivalent('Object', '~');
+  //equivalent('Object', '1&');
+  equivalent('@', '~');
+  equivalent('@', '1&');
+  equivalent('~', '1&');
+  //equivalent('List<Object>', 'List<@>');
+  //equivalent('List<Object>', 'List<~>');
+  //equivalent('List<Object>', 'List<1&>');
+  equivalent('List<@>', 'List<~>');
+  equivalent('List<@>', 'List<1&>');
+  equivalent('List<~>', 'List<1&>');
 }
 
 void strictSubtype(String s, String t) {