Retain async initializers in actors in async_without_await (#6436)

CHANGELOG.md

@@ -16,6 +16,10 @@
 
 ### Bug Fixes
 
+* Retain `async` initializers in actors in `async_without_await` rule.  
+  [SimplyDanny](https://github.com/SimplyDanny)
+  [#6423](https://github.com/realm/SwiftLint/issues/6423)
+
 * Ignore `override` functions in `async_without_await` rule.  
   [SimplyDanny](https://github.com/SimplyDanny)
   [#6416](https://github.com/realm/SwiftLint/issues/6416)

Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRule.swift

@@ -23,6 +23,7 @@ private extension AsyncWithoutAwaitRule {
 
     final class Visitor: ViolationsSyntaxVisitor<ConfigurationType> {
         private var functionScopes = Stack<FuncInfo>()
+        private var actorTypeStack = Stack<Bool>()
         private var pendingAsync: TokenSyntax?
 
         override func visit(_ node: FunctionDeclSyntax) -> SyntaxVisitorContinueKind {
@@ -72,7 +73,9 @@ private extension AsyncWithoutAwaitRule {
 
         override func visit(_ node: InitializerDeclSyntax) -> SyntaxVisitorContinueKind {
             if node.body != nil {
-                let asyncToken = node.needsToKeepAsync ? nil : node.signature.effectSpecifiers?.asyncSpecifier
+                let asyncToken = node.needsToKeepAsync || actorTypeStack.peek() == true
+                    ? nil
+                    : node.signature.effectSpecifiers?.asyncSpecifier
                 functionScopes.push(.init(asyncToken: asyncToken))
             }
             return .visitChildren
@@ -113,6 +116,42 @@ private extension AsyncWithoutAwaitRule {
             }
         }
 
+        override func visit(_: ActorDeclSyntax) -> SyntaxVisitorContinueKind {
+            actorTypeStack.push(true)
+            return .visitChildren
+        }
+
+        override func visitPost(_: ActorDeclSyntax) {
+            actorTypeStack.pop()
+        }
+
+        override func visit(_: ClassDeclSyntax) -> SyntaxVisitorContinueKind {
+            actorTypeStack.push(false)
+            return .visitChildren
+        }
+
+        override func visitPost(_: ClassDeclSyntax) {
+            actorTypeStack.pop()
+        }
+
+        override func visit(_: EnumDeclSyntax) -> SyntaxVisitorContinueKind {
+            actorTypeStack.push(false)
+            return .visitChildren
+        }
+
+        override func visitPost(_: EnumDeclSyntax) {
+            actorTypeStack.pop()
+        }
+
+        override func visit(_: StructDeclSyntax) -> SyntaxVisitorContinueKind {
+            actorTypeStack.push(false)
+            return .visitChildren
+        }
+
+        override func visitPost(_: StructDeclSyntax) {
+            actorTypeStack.pop()
+        }
+
         override func visit(_: FunctionParameterSyntax) -> SyntaxVisitorContinueKind {
             .skipChildren
         }

Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRuleExamples.swift

@@ -1,5 +1,13 @@
 internal struct AsyncWithoutAwaitRuleExamples {
     static let nonTriggeringExamples = [
+        Example("""
+        actor A {
+            init() async {
+                foo()
+            }
+            func foo() {}
+        }
+        """),
         Example("""
         func test() {
             func test() async {