[CFE] Fix crash on abstracty field with duplicate initializer

Change-Id: I8b33ab973ad0849c36ccec6b6136d53f1b1b2cd0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/397761
Commit-Queue: Jens Johansen <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

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

@@ -2014,7 +2014,8 @@ class AbstractOrExternalFieldEncoding implements FieldEncoding {
   @override
   Initializer buildErroneousInitializer(Expression effect, Expression value,
       {required int fileOffset}) {
-    throw new UnsupportedError("$runtimeType.buildDuplicatedInitializer");
+    return new ShadowInvalidFieldInitializer(type, value, effect)
+      ..fileOffset = fileOffset;
   }
 }
 

pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart

@@ -0,0 +1,8 @@
+// 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.
+
+abstract class Foo {
+  abstract int foo;
+  Foo(this.foo, this.foo) {}
+}

pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart.strong.expect

@@ -0,0 +1,34 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: Duplicated parameter name 'foo'.
+//   Foo(this.foo, this.foo) {}
+//                      ^^^
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Context: Other parameter named 'foo'.
+//   Foo(this.foo, this.foo) {}
+//            ^^^
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Error: Abstract fields cannot have initializers.
+// Try removing the field initializer or the 'abstract' keyword from the field declaration.
+//   Foo(this.foo, this.foo) {}
+//            ^^^
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: 'foo' was already initialized by this constructor.
+//   Foo(this.foo, this.foo) {}
+//                      ^
+//
+import self as self;
+import "dart:core" as core;
+
+abstract class Foo extends core::Object {
+  constructor •(core::int foo, core::int foo) → self::Foo
+    : final dynamic #t1 = invalid-expression "pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Error: Abstract fields cannot have initializers.
+Try removing the field initializer or the 'abstract' keyword from the field declaration.
+  Foo(this.foo, this.foo) {}
+           ^^^", final dynamic #t2 = invalid-expression "pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: 'foo' was already initialized by this constructor.
+  Foo(this.foo, this.foo) {}
+                     ^" {}
+  abstract get foo() → core::int;
+  abstract set foo(synthesized core::int #externalFieldValue) → void;
+}

pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart.strong.modular.expect

@@ -0,0 +1,34 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: Duplicated parameter name 'foo'.
+//   Foo(this.foo, this.foo) {}
+//                      ^^^
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Context: Other parameter named 'foo'.
+//   Foo(this.foo, this.foo) {}
+//            ^^^
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Error: Abstract fields cannot have initializers.
+// Try removing the field initializer or the 'abstract' keyword from the field declaration.
+//   Foo(this.foo, this.foo) {}
+//            ^^^
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: 'foo' was already initialized by this constructor.
+//   Foo(this.foo, this.foo) {}
+//                      ^
+//
+import self as self;
+import "dart:core" as core;
+
+abstract class Foo extends core::Object {
+  constructor •(core::int foo, core::int foo) → self::Foo
+    : final dynamic #t1 = invalid-expression "pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Error: Abstract fields cannot have initializers.
+Try removing the field initializer or the 'abstract' keyword from the field declaration.
+  Foo(this.foo, this.foo) {}
+           ^^^", final dynamic #t2 = invalid-expression "pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: 'foo' was already initialized by this constructor.
+  Foo(this.foo, this.foo) {}
+                     ^" {}
+  abstract get foo() → core::int;
+  abstract set foo(synthesized core::int #externalFieldValue) → void;
+}

pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart.strong.outline.expect

@@ -0,0 +1,20 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: Duplicated parameter name 'foo'.
+//   Foo(this.foo, this.foo) {}
+//                      ^^^
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Context: Other parameter named 'foo'.
+//   Foo(this.foo, this.foo) {}
+//            ^^^
+//
+import self as self;
+import "dart:core" as core;
+
+abstract class Foo extends core::Object {
+  constructor •(core::int foo, core::int foo) → self::Foo
+    ;
+  abstract get foo() → core::int;
+  abstract set foo(synthesized core::int #externalFieldValue) → void;
+}

pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart.strong.transformed.expect

@@ -0,0 +1,34 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: Duplicated parameter name 'foo'.
+//   Foo(this.foo, this.foo) {}
+//                      ^^^
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Context: Other parameter named 'foo'.
+//   Foo(this.foo, this.foo) {}
+//            ^^^
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Error: Abstract fields cannot have initializers.
+// Try removing the field initializer or the 'abstract' keyword from the field declaration.
+//   Foo(this.foo, this.foo) {}
+//            ^^^
+//
+// pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: 'foo' was already initialized by this constructor.
+//   Foo(this.foo, this.foo) {}
+//                      ^
+//
+import self as self;
+import "dart:core" as core;
+
+abstract class Foo extends core::Object {
+  constructor •(core::int foo, core::int foo) → self::Foo
+    : final dynamic #t1 = invalid-expression "pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:12: Error: Abstract fields cannot have initializers.
+Try removing the field initializer or the 'abstract' keyword from the field declaration.
+  Foo(this.foo, this.foo) {}
+           ^^^", final dynamic #t2 = invalid-expression "pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart:7:22: Error: 'foo' was already initialized by this constructor.
+  Foo(this.foo, this.foo) {}
+                     ^" {}
+  abstract get foo() → core::int;
+  abstract set foo(synthesized core::int #externalFieldValue) → void;
+}

pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart.textual_outline.expect

@@ -0,0 +1,4 @@
+abstract class Foo {
+  abstract int foo;
+  Foo(this.foo, this.foo) {}
+}

pkg/front_end/testcases/regress/abstract_field_duplicate_initializer.dart.textual_outline_modelled.expect

@@ -0,0 +1,4 @@
+abstract class Foo {
+  Foo(this.foo, this.foo) {}
+  abstract int foo;
+}