[cfe] Enable setter/getter pairs with mismatching types

The new functionality is guided by the flag 'getter-setter-error'.

Part of #58579

Change-Id: I540e1ac67d1a4fb244e57981311c0b56155050fc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/396821
Reviewed-by: Johnni Winther <[email protected]>
Commit-Queue: Chloe Stefantsova <[email protected]>

Author: chloestefantsova

pkg/front_end/lib/src/kernel/hierarchy/members_node.dart

@@ -939,12 +939,14 @@ class ClassMembersNodeBuilder extends MembersNodeBuilder {
           /// not a valid getter/setter in `Class` because the type of the getter
           /// `Super.property2` is _not_ a subtype of the setter
           /// `Mixin.property1`.
-          _membersBuilder.registerGetterSetterCheck(
-              new DelayedClassGetterSetterCheck(
-                  classBuilder as SourceClassBuilder,
-                  name,
-                  interfaceGetable,
-                  interfaceSetable));
+          SourceClassBuilder sourceClassBuilder =
+              classBuilder as SourceClassBuilder;
+          if (!sourceClassBuilder
+              .libraryBuilder.libraryFeatures.getterSetterError.isEnabled) {
+            _membersBuilder.registerGetterSetterCheck(
+                new DelayedClassGetterSetterCheck(sourceClassBuilder, name,
+                    interfaceGetable, interfaceSetable));
+          }
         }
       }
       overrides.collectOverrides(

pkg/front_end/lib/src/source/source_library_builder.dart

@@ -1164,9 +1164,12 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
       setterType = setterBuilder.procedure.setterType;
     }
 
-    if (getterType is InvalidType || setterType is InvalidType) {
-      // Don't report a problem as something else is wrong that has already
-      // been reported.
+    if (libraryFeatures.getterSetterError.isEnabled ||
+        getterType is InvalidType ||
+        setterType is InvalidType) {
+      // Don't report a problem because the it isn't considered a problem in the
+      // current Dart version or because something else is wrong that has
+      // already been reported.
     } else {
       bool isValid = typeEnvironment.isSubtypeOf(
           getterType, setterType, SubtypeCheckMode.withNullabilities);

pkg/front_end/testcases/getter_setter_error/arbitrary_mismatching_types.dart

@@ -0,0 +1,10 @@
+// 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.
+
+// See https://github.com/dart-lang/language/issues/2809.
+
+class A {
+  int get x => 42;
+  set x(String _) {}
+}

pkg/front_end/testcases/getter_setter_error/arbitrary_mismatching_types.dart.strong.expect

@@ -0,0 +1,12 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get x() → core::int
+    return 42;
+  set x(wildcard core::String _#wc0#formal) → void {}
+}

pkg/front_end/testcases/getter_setter_error/arbitrary_mismatching_types.dart.strong.modular.expect

@@ -0,0 +1,12 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get x() → core::int
+    return 42;
+  set x(wildcard core::String _#wc0#formal) → void {}
+}

pkg/front_end/testcases/getter_setter_error/arbitrary_mismatching_types.dart.strong.outline.expect

@@ -0,0 +1,12 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    ;
+  get x() → core::int
+    ;
+  set x(wildcard core::String _#wc0#formal) → void
+    ;
+}

pkg/front_end/testcases/getter_setter_error/arbitrary_mismatching_types.dart.strong.transformed.expect

@@ -0,0 +1,12 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get x() → core::int
+    return 42;
+  set x(wildcard core::String _#wc0#formal) → void {}
+}

pkg/front_end/testcases/getter_setter_error/arbitrary_mismatching_types.dart.textual_outline.expect

@@ -0,0 +1,4 @@
+class A {
+  int get x => 42;
+  set x(String _) {}
+}

pkg/front_end/testcases/getter_setter_error/arbitrary_mismatching_types.dart.textual_outline_modelled.expect

@@ -0,0 +1,4 @@
+class A {
+  int get x => 42;
+  set x(String _) {}
+}

pkg/front_end/testcases/getter_setter_error/folder.options

@@ -0,0 +1 @@
+--enable-experiment=getter-setter-error