Don't apply extensions to Never.

dart-lang/language#1003

Change-Id: Ie9526e8e362865754e84b5d9cda307dc7b07aaee
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150162
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

pkg/analyzer/lib/src/dart/resolver/extension_member_resolver.dart

@@ -10,6 +10,7 @@ import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/element/generic_inferrer.dart';
 import 'package:analyzer/src/dart/element/member.dart';
+import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
 import 'package:analyzer/src/dart/element/type_schema.dart';
 import 'package:analyzer/src/dart/resolver/resolution_result.dart';
@@ -252,6 +253,10 @@ class ExtensionMemberResolver {
   /// Return extensions for the [type] that match the given [name] in the
   /// current scope.
   List<_InstantiatedExtension> _getApplicable(DartType type, String name) {
+    if (identical(type, NeverTypeImpl.instance)) {
+      return const <_InstantiatedExtension>[];
+    }
+
     var candidates = _getExtensionsWithMember(name);
 
     var instantiatedExtensions = <_InstantiatedExtension>[];

pkg/analyzer/test/src/dart/resolution/extension_method_test.dart

@@ -1446,6 +1446,21 @@ class ExtensionMethodsExternalReferenceWithNnbdTest
   @override
   bool get typeToStringWithNullability => true;
 
+  test_instance_getter_fromInstance_Never() async {
+    await assertNoErrorsInCode('''
+extension E on Never {
+  int get foo => 0;
+}
+
+f(Never a) {
+  a.foo;
+}
+''');
+    var access = findNode.prefixed('a.foo');
+    assertElementNull(access);
+    assertType(access, 'Never');
+  }
+
   test_instance_getter_fromInstance_nullable() async {
     await assertNoErrorsInCode('''
 extension E on int? {
@@ -1476,6 +1491,28 @@ f(int? a) {
     assertType(identifier, 'int');
   }
 
+  test_instance_method_fromInstance_Never() async {
+    await assertErrorsInCode('''
+extension E on Never {
+  void foo() {}
+}
+
+f(Never a) {
+  a.foo();
+}
+''', [
+      error(HintCode.RECEIVER_OF_TYPE_NEVER, 57, 1),
+      error(HintCode.DEAD_CODE, 62, 3),
+    ]);
+    assertMethodInvocation2(
+      findNode.methodInvocation('a.foo()'),
+      element: null,
+      typeArgumentTypes: [],
+      invokeType: 'dynamic',
+      type: 'Never',
+    );
+  }
+
   test_instance_method_fromInstance_nullable() async {
     await assertNoErrorsInCode('''
 extension E on int? {