[wildcard-variables] Add a test on unnamed optional parameters with no default value.

Bug: dart-lang/language#3807
Change-Id: Ibeb29d3702b74379b64e8965c3ef9709c7bf2f41
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/369780
Commit-Queue: Kallen Tu <[email protected]>
Reviewed-by: Lasse Nielsen <[email protected]>

Author: kallentu

tests/language/wildcard_variables/unnamed_optional/unnamed_optional_error_test.dart

@@ -0,0 +1,65 @@
+// Copyright (c) 2024, 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 that we still need default values for `this._` and `super._` and that
+// we can't add default values to a `_` named parameter where you can't add 
+// default values.
+
+// SharedOptions=--enable-experiment=wildcard-variables
+
+class SuperClass {
+  SuperClass([int _]);
+  //              ^
+  // [analyzer] COMPILE_TIME_ERROR.MISSING_DEFAULT_VALUE_FOR_PARAMETER
+  // [cfe] The parameter '_' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
+  SuperClass.nullable([int? _]);
+}
+class SubClass extends SuperClass {
+  final int _;
+  SubClass([
+    this._,
+  //     ^
+  // [analyzer] COMPILE_TIME_ERROR.MISSING_DEFAULT_VALUE_FOR_PARAMETER
+  // [cfe] The parameter '_' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
+    super._,
+  //      ^
+  // [analyzer] COMPILE_TIME_ERROR.DUPLICATE_DEFINITION
+  // [analyzer] COMPILE_TIME_ERROR.MISSING_DEFAULT_VALUE_FOR_PARAMETER
+  // [cfe] Duplicated parameter name '_'.
+  // [cfe] The parameter '_' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
+  // [cfe] Type 'int' of the optional super-initializer parameter '_' doesn't allow 'null', but the parameter doesn't have a default value, and the default value can't be copied from the corresponding parameter of the super constructor.
+  ]);
+}
+class TypedSubClass extends SuperClass {
+  final int? _;
+  TypedSubClass([
+    int this._,
+    //       ^
+    // [analyzer] COMPILE_TIME_ERROR.MISSING_DEFAULT_VALUE_FOR_PARAMETER
+    // [cfe] The parameter '_' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
+    int super._,
+    //        ^
+    // [analyzer] COMPILE_TIME_ERROR.DUPLICATE_DEFINITION
+    // [analyzer] COMPILE_TIME_ERROR.MISSING_DEFAULT_VALUE_FOR_PARAMETER
+    // [cfe] Duplicated parameter name '_'.
+    // [cfe] The parameter '_' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
+    // [cfe] Type 'int' of the optional super-initializer parameter '_' doesn't allow 'null', but the parameter doesn't have a default value, and the default value can't be copied from the corresponding parameter of the super constructor.
+  ]) : super.nullable();
+}
+
+// Function type parameters cannot have default values.
+typedef F = void Function([int _ = 1]);
+//                               ^
+// [analyzer] SYNTACTIC_ERROR.DEFAULT_VALUE_IN_FUNCTION_TYPE
+// [cfe] Can't have a default value in a function type.
+
+// Redirecting factory constructors cannot have default values.
+class ReClass {
+  ReClass([int x = 0]);
+  factory ReClass.redir([int _ = 0]) = ReClass;
+  //                         ^
+  // [analyzer] COMPILE_TIME_ERROR.DEFAULT_VALUE_IN_REDIRECTING_FACTORY_CONSTRUCTOR
+  //                             ^
+  // [cfe] Can't have a default value here because any default values of 'ReClass' would be used instead.
+}

tests/language/wildcard_variables/unnamed_optional/unnamed_optional_no_default_test.dart

@@ -0,0 +1,61 @@
+// Copyright (c) 2024, 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.
+
+// Unnamed optional parameters, which are not initializing or super parameters,
+// that have no default values, have no errors.
+
+// SharedOptions=--enable-experiment=wildcard-variables
+
+import 'package:expect/expect.dart';
+
+class C {
+  C([int _]) {}
+  C.otherParams([int _, bool x = false, bool _ = true]) {}
+  C.otherParams2([int _ = 1, bool x = false, bool _]) {}
+
+  int foo([int _]) => 1;
+  int foo2([bool x = false, bool _, int _]) => 1;
+  int foo3([bool? x, bool _ = false, int _]) => 1;
+  int foo4([int _, bool? x, bool _ = false]) => 1;
+
+  static int fn([int _]) => 1;
+  static int fn2([bool x = false, bool _, int _]) => 1;
+  static int fn3([bool? x, bool _ = false, int _]) => 1;
+  static int fn4([int _, bool? x, bool _ = false]) => 1;
+}
+
+int _([bool _]) => 1;
+int topFoo2([bool x = false, bool _, int _]) => 1;
+int topFoo3([bool? x, bool _ = false, int _]) => 1;
+int topFoo4([int _, bool? x, bool _ = false]) => 1;
+
+void main() {
+  Expect.equals(1, _());
+  Expect.equals(1, topFoo2());
+  Expect.equals(1, topFoo3());
+  Expect.equals(1, topFoo4());
+
+  int foo([int _]) => 1;
+  int foo2([bool x = false, bool _, int _]) => 1;
+  int foo3([bool? x, bool _ = false, int _]) => 1;
+  int foo4([int _, bool? x, bool _ = false]) => 1;
+  Expect.equals(1, foo());
+  Expect.equals(1, foo2());
+  Expect.equals(1, foo3());
+  Expect.equals(1, foo4());
+
+  var c = C();
+  Expect.equals(1, c.foo());
+  Expect.equals(1, c.foo2());
+  Expect.equals(1, c.foo3());
+  Expect.equals(1, c.foo4());
+
+  Expect.equals(1, C.otherParams().foo());
+  Expect.equals(1, C.otherParams2().foo());
+
+  Expect.equals(1, C.fn());
+  Expect.equals(1, C.fn2());
+  Expect.equals(1, C.fn3());
+  Expect.equals(1, C.fn4());
+}