[CFE] Fix setter from extension used in for loop

Change-Id: I6cfbd7b8c5d72ea508dcdb7f0b15ddaab1e0700d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/398062
Commit-Queue: Jens Johansen <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

pkg/front_end/lib/src/type_inference/for_in.dart

@@ -7,6 +7,7 @@ import 'package:kernel/ast.dart';
 
 import '../base/instrumentation.dart' show InstrumentationValueForMember;
 import '../codes/cfe_codes.dart';
+import '../kernel/hierarchy/class_member.dart';
 import '../kernel/internal_ast.dart';
 import 'inference_results.dart';
 import 'inference_visitor.dart';
@@ -259,6 +260,57 @@ class StaticForInVariable implements ForInVariable {
   }
 }
 
+class ExtensionSetForInVariable implements ForInVariable {
+  final ExtensionSet extensionSet;
+  DartType? setterType;
+
+  ExtensionSetForInVariable(this.extensionSet);
+
+  @override
+  DartType computeElementType(InferenceVisitorBase visitor) {
+    ExpressionInferenceResult receiverResult = visitor.inferExpression(
+        extensionSet.receiver, const UnknownType(),
+        isVoidAllowed: false);
+
+    List<DartType> extensionTypeArguments =
+        visitor.computeExtensionTypeArgument(extensionSet.extension,
+            extensionSet.explicitTypeArguments, receiverResult.inferredType,
+            treeNodeForTesting: extensionSet);
+
+    DartType receiverType = visitor.getExtensionReceiverType(
+        extensionSet.extension, extensionTypeArguments);
+
+    ObjectAccessTarget target = new ExtensionAccessTarget(
+        receiverType,
+        extensionSet.target,
+        null,
+        ClassMemberKind.Setter,
+        extensionTypeArguments);
+
+    setterType = target.getSetterType(visitor);
+    return setterType!;
+  }
+
+  @override
+  Expression inferAssignment(InferenceVisitorBase visitor, DartType rhsType) {
+    assert(setterType != null);
+    Expression rhs = visitor.ensureAssignable(
+        setterType!, rhsType, extensionSet.value,
+        errorTemplate: templateForInLoopElementTypeNotAssignable,
+        nullabilityErrorTemplate:
+            templateForInLoopElementTypeNotAssignableNullability,
+        nullabilityPartErrorTemplate:
+            templateForInLoopElementTypeNotAssignablePartNullability,
+        isVoidAllowed: true);
+
+    extensionSet.value = rhs..parent = extensionSet;
+    ExpressionInferenceResult result = visitor.inferExpression(
+        extensionSet, const UnknownType(),
+        isVoidAllowed: true);
+    return result.expression;
+  }
+}
+
 class InvalidForInVariable implements ForInVariable {
   final Expression? expression;
 

pkg/front_end/lib/src/type_inference/inference_visitor.dart

@@ -1690,6 +1690,8 @@ class InferenceVisitorImpl extends InferenceVisitorBase
       return new SuperPropertyForInVariable(syntheticAssignment);
     } else if (syntheticAssignment is StaticSet) {
       return new StaticForInVariable(syntheticAssignment);
+    } else if (syntheticAssignment is ExtensionSet) {
+      return new ExtensionSetForInVariable(syntheticAssignment);
     } else if (syntheticAssignment is InvalidExpression || hasProblem) {
       return new InvalidForInVariable(syntheticAssignment);
     } else {

pkg/front_end/testcases/regress/extension_setter_in_for_in_loop.dart

@@ -0,0 +1,13 @@
+// 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.
+
+extension on String {
+  set foo(int value) {}
+  bar(List<int> input) {
+    foo = 42;
+    for (foo in input) {
+      print("inside loop");
+    }
+  }
+}

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

@@ -0,0 +1,19 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+extension /* unnamed */ _extension#0 on core::String {
+  method bar = self::_extension#0|bar;
+  method tearoff bar = self::_extension#0|get#bar;
+  set foo = self::_extension#0|set#foo;
+}
+static extension-member method _extension#0|set#foo(lowered final core::String #this, core::int value) → void {}
+static extension-member method _extension#0|bar(lowered final core::String #this, core::List<core::int> input) → dynamic {
+  self::_extension#0|set#foo(#this, 42);
+  for (final core::int #t1 in input) {
+    self::_extension#0|set#foo(#this, #t1);
+    core::print("inside loop");
+  }
+}
+static extension-member method _extension#0|get#bar(lowered final core::String #this) → (core::List<core::int>) → dynamic
+  return (core::List<core::int> input) → dynamic => self::_extension#0|bar(#this, input);

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

@@ -0,0 +1,19 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+extension /* unnamed */ _extension#0 on core::String {
+  method bar = self::_extension#0|bar;
+  method tearoff bar = self::_extension#0|get#bar;
+  set foo = self::_extension#0|set#foo;
+}
+static extension-member method _extension#0|set#foo(lowered final core::String #this, core::int value) → void {}
+static extension-member method _extension#0|bar(lowered final core::String #this, core::List<core::int> input) → dynamic {
+  self::_extension#0|set#foo(#this, 42);
+  for (final core::int #t1 in input) {
+    self::_extension#0|set#foo(#this, #t1);
+    core::print("inside loop");
+  }
+}
+static extension-member method _extension#0|get#bar(lowered final core::String #this) → (core::List<core::int>) → dynamic
+  return (core::List<core::int> input) → dynamic => self::_extension#0|bar(#this, input);

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

@@ -0,0 +1,15 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+extension /* unnamed */ _extension#0 on core::String {
+  method bar = self::_extension#0|bar;
+  method tearoff bar = self::_extension#0|get#bar;
+  set foo = self::_extension#0|set#foo;
+}
+static extension-member method _extension#0|set#foo(lowered final core::String #this, core::int value) → void
+  ;
+static extension-member method _extension#0|bar(lowered final core::String #this, core::List<core::int> input) → dynamic
+  ;
+static extension-member method _extension#0|get#bar(lowered final core::String #this) → (core::List<core::int>) → dynamic
+  return (core::List<core::int> input) → dynamic => self::_extension#0|bar(#this, input);

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

@@ -0,0 +1,25 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+extension /* unnamed */ _extension#0 on core::String {
+  method bar = self::_extension#0|bar;
+  method tearoff bar = self::_extension#0|get#bar;
+  set foo = self::_extension#0|set#foo;
+}
+static extension-member method _extension#0|set#foo(lowered final core::String #this, core::int value) → void {}
+static extension-member method _extension#0|bar(lowered final core::String #this, core::List<core::int> input) → dynamic {
+  self::_extension#0|set#foo(#this, 42);
+  {
+    synthesized core::Iterator<core::int> :sync-for-iterator = input.{core::Iterable::iterator}{core::Iterator<core::int>};
+    for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+      final core::int #t1 = :sync-for-iterator.{core::Iterator::current}{core::int};
+      {
+        self::_extension#0|set#foo(#this, #t1);
+        core::print("inside loop");
+      }
+    }
+  }
+}
+static extension-member method _extension#0|get#bar(lowered final core::String #this) → (core::List<core::int>) → dynamic
+  return (core::List<core::int> input) → dynamic => self::_extension#0|bar(#this, input);

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

@@ -0,0 +1,4 @@
+extension on String {
+  set foo(int value) {}
+  bar(List<int> input) {}
+}

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

@@ -0,0 +1,4 @@
+extension on String {
+  bar(List<int> input) {}
+  set foo(int value) {}
+}