Concurrency: Local functions should inherit isolation from context

Instead of looking at captures, which wasn't sound with
recursive local functions; we would look at the captures of
the function currently being type checked, which are not
available yet.

Author: slavapestov

lib/Sema/TypeCheckConcurrency.cpp

@@ -5174,9 +5174,7 @@ ActorIsolation ActorIsolationRequest::evaluate(
         llvm_unreachable("context cannot have erased isolation");
 
       case ActorIsolation::ActorInstance:
-        if (auto param = func->getCaptureInfo().getIsolatedParamCapture())
-          return inferredIsolation(enclosingIsolation);
-        break;
+        return inferredIsolation(enclosingIsolation);
 
       case ActorIsolation::GlobalActor:
         return inferredIsolation(enclosingIsolation);

test/Concurrency/actor_isolation.swift

@@ -755,6 +755,8 @@ func checkLocalFunctions() async {
   print(k)
 }
 
+func callee(_: () -> ()) {}
+
 @available(SwiftStdlib 5.1, *)
 actor LocalFunctionIsolatedActor {
   func a() -> Bool { // expected-note{{calls to instance method 'a()' from outside of its actor context are implicitly asynchronous}}
@@ -774,6 +776,30 @@ actor LocalFunctionIsolatedActor {
     }
     return c()
   }
+
+  func hasRecursiveLocalFunction() {
+    func recursiveLocalFunction(n: Int) {
+      _ = a()
+      callee { _ = a() }
+      if n > 0 { recursiveLocalFunction(n: n - 1) }
+    }
+
+    recursiveLocalFunction(n: 10)
+  }
+
+  func hasRecursiveLocalFunctions() {
+    recursiveLocalFunction()
+
+    func recursiveLocalFunction() {
+      anotherRecursiveLocalFunction()
+    }
+
+    func anotherRecursiveLocalFunction() {
+      callee { _ = a() }
+      _ = a()
+    }
+  }
+
 }
 
 // ----------------------------------------------------------------------