[element model] migrate parameter_assignments

Bug: https://github.com/dart-lang/linter/issues/5099
Change-Id: I8b674c1860e4c1fc492948670698a6ca9ee99ce0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/391567
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Phil Quitslund <[email protected]>

Author: pq

pkg/analyzer/lib/src/dart/ast/ast.dart

@@ -8166,13 +8166,15 @@ sealed class FunctionBodyImpl extends AstNodeImpl implements FunctionBody {
   @experimental
   @override
   bool isPotentiallyMutatedInScope2(VariableElement2 variable) {
-    if (variable is LocalVariableElementImpl2) {
-      return isPotentiallyMutatedInScope(variable.wrappedElement);
-    }
-    if (variable case VariableElement variable) {
-      return isPotentiallyMutatedInScope(variable);
-    }
-    return false;
+    return switch (variable) {
+      LocalVariableElementImpl2() =>
+        isPotentiallyMutatedInScope(variable.wrappedElement),
+      VariableElement() =>
+        isPotentiallyMutatedInScope(variable as VariableElement),
+      FormalParameterElement(:VariableElement firstFragment) =>
+        isPotentiallyMutatedInScope(firstFragment),
+      _ => false,
+    };
   }
 
   /// Dispatch this function body to the resolver, imposing [imposedType] as the

pkg/linter/analyzer_use_new_elements.txt

@@ -110,6 +110,7 @@ lib/src/rules/one_member_abstracts.dart
 lib/src/rules/only_throw_errors.dart
 lib/src/rules/package_api_docs.dart
 lib/src/rules/package_prefixed_library_names.dart
+lib/src/rules/parameter_assignments.dart
 lib/src/rules/prefer_adjacent_string_concatenation.dart
 lib/src/rules/prefer_asserts_with_message.dart
 lib/src/rules/prefer_bool_in_asserts.dart

pkg/linter/lib/src/rules/parameter_assignments.dart

@@ -4,7 +4,7 @@
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
-import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
 
 import '../analyzer.dart';
 
@@ -18,7 +18,7 @@ bool _isFormalParameterReassigned(
     FormalParameter parameter, AssignmentExpression assignment) {
   var leftHandSide = assignment.leftHandSide;
   return leftHandSide is SimpleIdentifier &&
-      leftHandSide.staticElement == parameter.declaredElement;
+      leftHandSide.element == parameter.declaredFragment?.element;
 }
 
 class ParameterAssignments extends LintRule {
@@ -51,7 +51,7 @@ class _DeclarationVisitor extends RecursiveAstVisitor<void> {
       {required this.paramIsNotNullByDefault,
       required this.paramDefaultsToNull});
 
-  Element? get parameterElement => parameter.declaredElement;
+  Element2? get parameterElement => parameter.declaredFragment?.element;
 
   void checkPatternElements(DartPattern node) {
     NodeList<PatternField>? fields;
@@ -112,8 +112,7 @@ class _DeclarationVisitor extends RecursiveAstVisitor<void> {
   visitPostfixExpression(PostfixExpression node) {
     if (paramIsNotNullByDefault) {
       var operand = node.operand;
-      if (operand is SimpleIdentifier &&
-          operand.staticElement == parameterElement) {
+      if (operand is SimpleIdentifier && operand.element == parameterElement) {
         reportLint(node);
       }
     }
@@ -125,8 +124,7 @@ class _DeclarationVisitor extends RecursiveAstVisitor<void> {
   visitPrefixExpression(PrefixExpression node) {
     if (paramIsNotNullByDefault) {
       var operand = node.operand;
-      if (operand is SimpleIdentifier &&
-          operand.staticElement == parameterElement) {
+      if (operand is SimpleIdentifier && operand.element == parameterElement) {
         reportLint(node);
       }
     }
@@ -155,9 +153,9 @@ class _Visitor extends SimpleAstVisitor<void> {
     if (parameterList == null) return;
 
     for (var parameter in parameterList.parameters) {
-      var declaredElement = parameter.declaredElement;
+      var declaredElement = parameter.declaredFragment?.element;
       if (declaredElement != null &&
-          body.isPotentiallyMutatedInScope(declaredElement)) {
+          body.isPotentiallyMutatedInScope2(declaredElement)) {
         var paramIsNotNullByDefault = parameter is SimpleFormalParameter ||
             _isDefaultFormalParameterWithDefaultValue(parameter);
         var paramDefaultsToNull = parameter is DefaultFormalParameter &&
@@ -173,9 +171,8 @@ class _Visitor extends SimpleAstVisitor<void> {
 }
 
 extension on AstNode {
-  Element? get element {
-    var self = this;
-    if (self is AssignedVariablePattern) return self.element;
-    return null;
-  }
+  Element2? get element => switch (this) {
+        AssignedVariablePattern(:var element2) => element2,
+        _ => null,
+      };
 }