unnecessary_final support for ForEachPartsWithPatterns (#4288)

* `unnecessary_final` support for `ForEachPartsWithPattern`s

* --

Author: pq

lib/src/extensions.dart

@@ -427,6 +427,10 @@ extension NullableAstNodeExtension on AstNode? {
   }
 }
 
+extension TokenExtension on Token? {
+  bool get isFinal => this?.keyword == Keyword.FINAL;
+}
+
 extension TokenTypeExtension on TokenType {
   TokenType get inverted => switch (this) {
         TokenType.LT_EQ => TokenType.GT_EQ,

lib/src/rules/prefer_final_locals.dart

@@ -3,11 +3,11 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/ast/ast.dart';
-import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 
 import '../analyzer.dart';
+import '../extensions.dart';
 
 const _desc =
     r'Prefer final for variable declarations if they are not reassigned.';
@@ -191,11 +191,3 @@ extension on AstNode {
     return false;
   }
 }
-
-extension on Token? {
-  bool get isFinal {
-    var self = this;
-    if (self == null) return false;
-    return self.keyword == Keyword.FINAL;
-  }
-}

lib/src/rules/unnecessary_final.dart

@@ -7,6 +7,7 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 
 import '../analyzer.dart';
+import '../extensions.dart';
 
 const _desc = "Don't use `final` for local variables.";
 
@@ -122,6 +123,12 @@ class _Visitor extends SimpleAstVisitor<void> {
         var errorCode = getErrorCode(loopVariable.type);
         rule.reportLintForToken(loopVariable.keyword, errorCode: errorCode);
       }
+    } else if (forLoopParts is ForEachPartsWithPattern) {
+      var keyword = forLoopParts.keyword;
+      if (keyword.isFinal) {
+        rule.reportLintForToken(keyword,
+            errorCode: UnnecessaryFinal.withoutType);
+      }
     }
   }
 

test/rules/unnecessary_final_test.dart

@@ -129,6 +129,16 @@ f() {
     ]);
   }
 
+  test_recordPattern_destructured_forEach() async {
+    await assertDiagnostics(r'''
+f() {
+  for (final (a, b) in [(1, 2)]) { }
+}
+''', [
+      lint(13, 5),
+    ]);
+  }
+
   test_recordPattern_destructured_ok() async {
     await assertNoDiagnostics(r'''
 f() {