Merge pull request #42016 from angela-laar/async_inout_capture

[Concurrency] Improve diagnostic for inout params with Sendable closures

Author: kavon

include/swift/AST/DiagnosticsSema.def

@@ -4587,6 +4587,10 @@ ERROR(concurrent_access_of_local_capture,none,
       "%select{mutation of|reference to}0 captured %1 %2 in "
       "concurrently-executing code",
       (bool, DescriptiveDeclKind, DeclName))
+ERROR(concurrent_access_of_inout_param,none,
+      "mutable capture of 'inout' parameter %0 is not allowed in "
+      "concurrently-executing code",
+      (DeclName))
 ERROR(non_sendable_capture,none,
       "capture of %1 with non-sendable type %0 in a `@Sendable` closure",
       (Type, DeclName))

lib/Sema/TypeCheckConcurrency.cpp

@@ -2567,6 +2567,13 @@ namespace {
           return false;
         }
 
+        if (auto param =  dyn_cast<ParamDecl>(value)){
+          if(param->isInOut()){
+              ctx.Diags.diagnose(loc, diag::concurrent_access_of_inout_param, param->getName());
+              return true;
+          }
+        }
+
         // Otherwise, we have concurrent access. Complain.
         ctx.Diags.diagnose(
             loc, diag::concurrent_access_of_local_capture,

test/Concurrency/async_tasks.swift

@@ -128,3 +128,12 @@ func test_detached_throwing() async -> String {
     print("caught: \(error)")
   }
 }
+
+// ==== Detached Tasks with inout Params---------------------------------------
+@available(SwiftStdlib 5.1, *)
+func printOrderNumber(n: inout Int) async {
+  Task.detached {
+      n+=1 //expected-error {{mutable capture of 'inout' parameter 'n' is not allowed in concurrently-executing code}}
+      print(n) //expected-error {{mutable capture of 'inout' parameter 'n' is not allowed in concurrently-executing code}}
+  }
+}

test/Concurrency/taskgroup_cancelAll_from_child.swift

@@ -13,7 +13,8 @@ func test_taskGroup_cancelAll() async {
 
        group.spawn {
          group.cancelAll() //expected-warning{{capture of 'group' with non-sendable type 'TaskGroup<Int>' in a `@Sendable` closure}}
-                           //expected-error@-1{{reference to captured parameter 'group' in concurrently-executing code}}
+                           //expected-error@-1{{mutable capture of 'inout' parameter 'group' is not allowed in concurrently-executing code}}
+
          return 0
        }
        group.spawn { [group] in