[vm, tfa] Fix tree-shaking of late final fields with initializers

TFA tree shaker removes initializers of fields which cannot be accessed
but retained due to an entry point pragma / dynamic interface.

For late final fields with initializers that changes semantics as
late final fields without initializers have an implicit setter.
Such setter is not accounted in the kernel AST
(Field.setterReference == null and Field.hasSetter == false) and
it doesn't get an assigned selector id, which causes a crash in
dispatch table generator.

The change fixes this bug by retaining initializers for late final
fields. The initializer code is still replaced with
throw "Attempt to execute code removed by Dart AOT compiler (TFA)".

TEST=pkg/vm/testcases/transformations/type_flow/transformer/regress_b404559785.dart

Bug: b/404559785
Change-Id: Id998a715ea75a4768414997ce66bcdd1d4f19189
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/416720
Commit-Queue: Alexander Markov <[email protected]>
Reviewed-by: Slava Egorov <[email protected]>
Reviewed-by: Sigmund Cherem <[email protected]>

Author: alexmarkov

pkg/vm/lib/transformations/type_flow/transformer.dart

@@ -2303,8 +2303,14 @@ class _TreeShakerPass2 extends RemovingTransformer {
         }
         Statistics.methodBodiesDropped++;
       } else if (node is Field) {
-        node.initializer = null;
-        Statistics.fieldInitializersDropped++;
+        // Do not remove initializers of late final fields as
+        // late final fields without initializer would have
+        // an additional implicit setter which was not accounted
+        // (Field.setterReference == null and Field.hasSetter == false).
+        if (!(node.isLate && node.isFinal)) {
+          node.initializer = null;
+          Statistics.fieldInitializersDropped++;
+        }
       } else if (node is Constructor) {
         _makeUnreachableBody(node.function);
         _removeDefaultValuesOfParameters(node.function);

pkg/vm/test/common_test_utils.dart

@@ -191,11 +191,11 @@ different kernel AST for the same Dart programs.
 
 In order to re-generate expectations run tests with -D$kUpdateExpectations=true VM option:
 
-  tools/test.py -m release --vm-options -D$kUpdateExpectations=true pkg/vm/
+  tools/test.py -m release --vm-options -D$kUpdateExpectations=true --timeout 600 pkg/vm/
 
 In order to dump actual results into .actual files run tests with -D$kDumpActualResult=true VM option:
 
-  tools/test.py -m release --vm-options -D$kDumpActualResult=true pkg/vm/
+  tools/test.py -m release --vm-options -D$kDumpActualResult=true --timeout 600 pkg/vm/
 
 """);
     }

pkg/vm/testcases/transformations/type_flow/transformer/regress_b404559785.dart

@@ -0,0 +1,19 @@
+// Copyright (c) 2025, 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.
+
+// Verifies that TFA does not remove a field initializer of a late final
+// field with initializer as that would add an extra implicit setter.
+// Regression test for b/404559785.
+
+class Foo {
+  int v;
+  Foo(this.v);
+
+  @pragma('vm:entry-point')
+  late final int hashCode = int.parse('1');
+}
+
+void main() {
+  print(Foo);
+}

pkg/vm/testcases/transformations/type_flow/transformer/regress_b404559785.dart.expect

@@ -0,0 +1,22 @@
+library #lib;
+import self as self;
+import "dart:core" as core;
+
+abstract class Foo extends core::Object {
+
+  [@vm.unreachable.metadata=]
+  [@vm.procedure-attributes.metadata=methodOrSetterCalledDynamically:false,getterCalledDynamically:false,hasThisUses:false,hasNonThisUses:false,hasTearOffUses:false,getterSelectorId:1]
+  @#C3
+  late final field core::int hashCode = throw "Attempt to execute code removed by Dart AOT compiler (TFA)";
+}
+
+[@vm.inferred-return-type.metadata=dart.core::Null? (value: null)]
+static method main() → void {
+  core::print(#C4);
+}
+constants  {
+  #C1 = "vm:entry-point"
+  #C2 = null
+  #C3 = core::pragma {name:#C1, options:#C2}
+  #C4 = TypeLiteralConstant(self::Foo)
+}