test function isolation expression

(cherry picked from commit 12ff5ee)

Author: angela-laar

lib/Sema/CSSimplify.cpp

@@ -9762,7 +9762,7 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
   // member that extracts the isolation value.
   if (auto *fn = instanceTy->getAs<FunctionType>()) {
     if (fn->getIsolation().isErased() &&
-        memberName.getBaseIdentifier().str() == "isolation") {
+        memberName.isSimpleName(Context.Id_isolation)) {
       result.ViableCandidates.push_back(
         OverloadChoice(baseTy, OverloadChoiceKind::ExtractFunctionIsolation));
     }

test/Concurrency/isolated_any.swift

@@ -93,6 +93,34 @@ func extractFunctionIsolationExpr(
 
   // Only `@isolated(any)` functions have `.isolation`
   let myActor = A()
+  let _: (any Actor)? = myActor.actorFunction.isolation // expected-error {{value of type '@Sendable () -> ()' has no member 'isolation'}}
   let _: (any Actor)? = myActor.asyncActorFunction.isolation // expected-error {{value of type '@Sendable () async -> ()' has no member 'isolation'}}
+  let _: (any Actor)? = myActor.asyncThrowsActorFunction.isolation // expected-error {{value of type '@Sendable () async throws -> ()' has no member 'isolation'}}
+  let _: (any Actor)? = myActor.actorFunctionWithArgs.isolation // expected-error {{value of type '@Sendable (Int) async -> String' has no member 'isolation'}}
+
   let _: (any Actor)? = globalNonisolatedFunction.isolation // expected-error {{value of type '@Sendable () -> ()' has no member 'isolation'}}
+  let _: (any Actor)? = globalMainActorFunction.isolation // expected-error {{value of type '@MainActor @Sendable () -> ()' has no member 'isolation'}}
+}
+
+func requireDotIsolation(_ fn: (any Actor)?) -> (any Actor)? { return fn }
+
+func testDotIsolation() {
+  let _ : (any Actor)? = requireDotIsolation(globalMainActorFunction.isolation) // expected-error {{value of type '@MainActor @Sendable () -> ()' has no member 'isolation'}}
+  let _ : (any Actor)? = requireDotIsolation(globalNonisolatedFunction.isolation) // expected-error {{value of type '@Sendable () -> ()' has no member 'isolation'}}
+}
+
+func testFunctionIsolationExpr1(_ fn: (@isolated(any) () -> Void)?) -> (any Actor)? {
+  return fn?.isolation
+}
+
+func testFunctionIsolationExpr2(_ fn: Optional<(@isolated(any) () -> Void)>) -> Optional<any Actor> {
+  return fn?.isolation
+}
+
+func testFunctionIsolationExprTuple(
+  _ fn1: (@isolated(any) () -> Void)?,
+  _ fn2: (@isolated(any) () -> Void)?
+) -> ((any Actor)?, (any Actor)?)
+{
+  return (fn1?.isolation, fn2?.isolation)
 }