Support primary constructors in avoid_unused_constructor_parameters

Fixes #62505

Change-Id: Ic25a525ade7ac454a09ff1934ee4baec95636607
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/475681
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>

Author: srawlins

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

@@ -34,15 +34,16 @@ class AvoidUnusedConstructorParameters extends AnalysisRule {
   ) {
     var visitor = _Visitor(this);
     registry.addConstructorDeclaration(this, visitor);
+    registry.addPrimaryConstructorDeclaration(this, visitor);
   }
 }
 
 class _ConstructorVisitor extends RecursiveAstVisitor<void> {
-  final ConstructorDeclaration element;
+  final FormalParameterList parameterList;
   final Set<FormalParameter> unusedParameters;
 
-  _ConstructorVisitor(this.element)
-    : unusedParameters = element.parameters.parameters.where((p) {
+  _ConstructorVisitor(this.parameterList)
+    : unusedParameters = parameterList.parameters.where((p) {
         var element = p.declaredFragment?.element;
         return element != null &&
             element is! FieldFormalParameterElement &&
@@ -70,10 +71,33 @@ class _Visitor extends SimpleAstVisitor<void> {
     if (node.redirectedConstructor != null) return;
     if (node.externalKeyword != null) return;
 
-    var constructorVisitor = _ConstructorVisitor(node);
-    node.body.visitChildren(constructorVisitor);
-    for (var i in node.initializers) {
-      i.visitChildren(constructorVisitor);
+    _checkConstructorParameters(
+      parameterList: node.parameters,
+      initializers: node.initializers,
+      body: node.body,
+    );
+  }
+
+  @override
+  void visitPrimaryConstructorDeclaration(PrimaryConstructorDeclaration node) {
+    _checkConstructorParameters(
+      parameterList: node.formalParameters,
+      initializers: node.body?.initializers,
+      body: node.body?.body,
+    );
+  }
+
+  void _checkConstructorParameters({
+    required FormalParameterList parameterList,
+    required List<ConstructorInitializer>? initializers,
+    required FunctionBody? body,
+  }) {
+    var constructorVisitor = _ConstructorVisitor(parameterList);
+    body?.visitChildren(constructorVisitor);
+    if (initializers != null) {
+      for (var i in initializers) {
+        i.visitChildren(constructorVisitor);
+      }
     }
 
     for (var parameter in constructorVisitor.unusedParameters) {

pkg/linter/test/rules/avoid_unused_constructor_parameters_test.dart

@@ -142,6 +142,12 @@ class B extends A {
 ''');
   }
 
+  test_unused_declaring_primary() async {
+    await assertNoDiagnostics(r'''
+class C([final int p = 0]);
+''');
+  }
+
   test_unused_optionalPositional() async {
     await assertDiagnostics(
       r'''
@@ -153,6 +159,15 @@ class C {
     );
   }
 
+  test_unused_optionalPositional_primary() async {
+    await assertDiagnostics(
+      r'''
+class C([int p = 0]);
+''',
+      [lint(9, 9)],
+    );
+  }
+
   test_unused_requiredPositional() async {
     await assertDiagnostics(
       r'''
@@ -174,6 +189,16 @@ class C {
 ''');
   }
 
+  test_usedInConstructorBody_primary() async {
+    await assertNoDiagnostics(r'''
+class C({int p = 0}) {
+  this {
+   p;
+  }
+}
+''');
+  }
+
   test_usedInConstructorInitializer() async {
     await assertNoDiagnostics(r'''
 class C {
@@ -183,6 +208,14 @@ class C {
 ''');
   }
 
+  test_usedInConstructorInitializer_primary() async {
+    await assertNoDiagnostics(r'''
+class C({int p = 0}) {
+  this : assert(p > 0);
+}
+''');
+  }
+
   test_usedInRedirectingInitializer() async {
     await assertNoDiagnostics(r'''
 class C {
@@ -206,6 +239,19 @@ class D extends C {
 ''');
   }
 
+  test_usedInSuperInitializer_primary() async {
+    await assertNoDiagnostics(r'''
+class C {
+  int p;
+  C(this.p);
+}
+
+class D(int p) extends C {
+  this : super(p);
+}
+''');
+  }
+
   test_wildcardParam() async {
     await assertNoDiagnostics(r'''
 class C {