From a0414c919d1ded68cdda585bd9a441eff43ccadb Mon Sep 17 00:00:00 2001
From: Nandhini Subramani <42835327+nandhinisubbu@users.noreply.github.com>
Date: Wed, 8 Oct 2025 22:36:56 +0530
Subject: [PATCH] Ignore `@concurrent` functions in `async_without_await` rule
 (#6284)

---
 CHANGELOG.md                                  |  5 ++++
 .../Rules/Lint/AsyncWithoutAwaitRule.swift    | 15 +++++++---
 .../Lint/AsyncWithoutAwaitRuleExamples.swift  | 28 +++++++++++++++++++
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 29af176ae..42d4a3111 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -66,6 +66,11 @@
   [SimplyDanny](https://github.com/SimplyDanny)
   [#6253](https://github.com/realm/SwiftLint/issues/6235)
 
+* Exclude `@concurrent` functions from `async_without_await` rule analysis.
+  `@concurrent` functions requires `aysnc` in any case.  
+  [nandhinisubbu](https://github.com/nandhinisubbu)
+  [#6283](https://github.com/realm/SwiftLint/issues/6283)
+
 ## 0.61.0: Even Fresher Breeze
 
 ### Breaking
diff --git a/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRule.swift b/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRule.swift
index 9e3e67ec8..7b8b0755b 100644
--- a/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRule.swift
+++ b/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRule.swift
@@ -30,7 +30,9 @@ private extension AsyncWithoutAwaitRule {
                 return .visitChildren
             }
 
-            let asyncToken = node.signature.effectSpecifiers?.asyncSpecifier
+            // @concurrent functions require the async keyword even without await calls
+            let asyncToken = node.attributes.contains(attributeNamed: "concurrent")
+                ? nil : node.signature.effectSpecifiers?.asyncSpecifier
             functionScopes.push(.init(asyncToken: asyncToken))
 
             return .visitChildren
@@ -42,8 +44,11 @@ private extension AsyncWithoutAwaitRule {
             }
         }
 
-        override func visit(_: ClosureExprSyntax) -> SyntaxVisitorContinueKind {
-            functionScopes.push(.init(asyncToken: pendingAsync))
+        override func visit(_ node: ClosureExprSyntax) -> SyntaxVisitorContinueKind {
+            // @concurrent closures require the async keyword even without await calls
+            let asyncToken = (node.signature?.attributes.contains(attributeNamed: "concurrent") ?? false)
+                ? nil : pendingAsync
+            functionScopes.push(.init(asyncToken: asyncToken))
             pendingAsync = nil
             return .visitChildren
         }
@@ -78,7 +83,9 @@ private extension AsyncWithoutAwaitRule {
                 return .visitChildren
             }
 
-            let asyncToken = node.signature.effectSpecifiers?.asyncSpecifier
+            // @concurrent can be applied to initializers
+            let asyncToken = node.attributes.contains(attributeNamed: "concurrent")
+                ? nil : node.signature.effectSpecifiers?.asyncSpecifier
             functionScopes.push(.init(asyncToken: asyncToken))
 
             return .visitChildren
diff --git a/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRuleExamples.swift b/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRuleExamples.swift
index 7d4a6564c..91b4a0112 100644
--- a/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRuleExamples.swift
+++ b/Source/SwiftLintBuiltInRules/Rules/Lint/AsyncWithoutAwaitRuleExamples.swift
@@ -160,6 +160,34 @@ internal struct AsyncWithoutAwaitRuleExamples {
             }
         }
         """, excludeFromDocumentation: true),
+        Example("""
+        @concurrent
+        func concurrentFunction() async {
+            performWork()
+        }
+        """),
+        Example("""
+        struct S: Sendable {
+            @concurrent
+            func alwaysSwitch() async {
+                // This is valid - @concurrent functions require async even without await
+            }
+        }
+        """),
+        Example("""
+        struct ConcurrentInitExample {
+            @concurrent
+            init() async {
+                setup()
+            }
+            func setup() {}
+        }
+        """),
+        Example("""
+        struct ConcurrentClosureExample {
+            let c: () async -> Int = { @concurrent in 1 }
+        }
+        """),
     ]
 
     static let triggeringExamples = [