[Concurrency] References to nonisolated(nonsending) properties don't leave caller's isolation

Make sure that referencing `nonisolated(nonsending)` properties,
especially through a witness is as not treated as leaving the
isolation domain of the caller.

Resolves: rdar://153922620

Author: xedin

lib/Sema/TypeCheckConcurrency.cpp

@@ -7919,6 +7919,9 @@ ActorReferenceResult ActorReferenceResult::forReference(
         getInnermostIsolatedContext(fromDC, getClosureActorIsolation);
   }
 
+  if (declIsolation.isCallerIsolationInheriting())
+    return forSameConcurrencyDomain(declIsolation, options);
+
   // When the declaration is not actor-isolated, it can always be accessed
   // directly.
   if (!declIsolation.isActorIsolated()) {

test/Concurrency/attr_execution/witnesses.swift

@@ -0,0 +1,102 @@
+// RUN: %target-swift-emit-silgen %s -swift-version 6 -target %target-swift-5.1-abi-triple | %FileCheck %s
+
+// REQUIRES: asserts
+// REQUIRES: concurrency
+
+protocol P {
+  nonisolated(nonsending) var prop: String { get async }
+  nonisolated(nonsending) func fn() async
+}
+
+struct S: P {
+  var prop: String {
+    get async { "" }
+  }
+
+  func fn() async {
+  }
+}
+
+// CHECK-LABEL: sil hidden [ossa] @$s9witnesses21testMainActorDispatch1tyx_tYaAA1PRzlF : $@convention(thin) @async <T where T : P> (@in_guaranteed T) -> ()
+// CHECK: [[MAIN_ACTOR_TYPE:%.*]] = metatype $@thick MainActor.Type
+// CHECK: [[MAIN_ACTOR:%.*]] = apply {{.*}}([[MAIN_ACTOR_TYPE]]) : $@convention(method) (@thick MainActor.Type) -> @owned MainActor
+// CHECK-NEXT: [[BORROWED_MAIN_ACTOR:%.*]] = begin_borrow [[MAIN_ACTOR]]
+// CHECK-NEXT: hop_to_executor [[BORROWED_MAIN_ACTOR]]
+// CHECK-NEXT: [[MAIN_ACTOR_COPY:%.*]] = copy_value [[BORROWED_MAIN_ACTOR]]
+// CHECK-NEXT: [[ERASED_TO_ACTOR:%.*]] = init_existential_ref [[MAIN_ACTOR_COPY]] : $MainActor : $MainActor, $any Actor
+// CHECK-NEXT: [[CONTEXT_ISOLATION:%.*]] = enum $Optional<any Actor>, #Optional.some!enumelt, [[ERASED_TO_ACTOR]]
+// CHECK-NEXT: [[PROP_WITNESS:%.*]] = witness_method $T, #P.prop!getter : <Self where Self : P> (Self) -> () async -> String : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> @owned String
+// CHECK-NEXT: {{.*}} = apply [[PROP_WITNESS]]<T>([[CONTEXT_ISOLATION]], %0) : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> @owned String
+// CHECK: hop_to_executor [[BORROWED_MAIN_ACTOR]]
+// CHECK: [[MAIN_ACTOR_COPY:%.*]] = copy_value [[BORROWED_MAIN_ACTOR]]
+// CHECK-NEXT: [[ERASED_TO_ACTOR:%.*]] = init_existential_ref [[MAIN_ACTOR_COPY]] : $MainActor : $MainActor, $any Actor
+// CHECK-NEXT: [[CONTEXT_ISOLATION:%.*]] = enum $Optional<any Actor>, #Optional.some!enumelt, [[ERASED_TO_ACTOR]]
+// CHECK-NEXT: [[FN_WITNESS:%.*]] = witness_method $T, #P.fn : <Self where Self : P> (Self) -> () async -> () : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> ()
+// CHECK-NEXT: {{.*}} = apply [[FN_WITNESS]]<T>([[CONTEXT_ISOLATION]], %0) : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> ()
+// CHECK: } // end sil function '$s9witnesses21testMainActorDispatch1tyx_tYaAA1PRzlF'
+@MainActor
+func testMainActorDispatch<T: P>(t: T) async {
+  _ = await t.prop
+  _ = await t.fn()
+}
+
+// CHECK-LABEL: sil hidden [ossa] @$s9witnesses19testGenericExecutor1tyx_tYaAA1PRzlF : $@convention(thin) @async <T where T : P> (@in_guaranteed T) -> ()
+// CHECK: [[CONTEXT_ISOLATION:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
+// CHECK-NEXT: hop_to_executor [[CONTEXT_ISOLATION]]
+// CHECK-NEXT: [[ISOLATION_ERASED_TO_ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
+// CHECK-NEXT: [[PROP_WITNESS:%.*]] = witness_method $T, #P.prop!getter : <Self where Self : P> (Self) -> () async -> String : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> @owned String
+// CHECK-NEXT: {{.*}} = apply [[PROP_WITNESS]]<T>([[ISOLATION_ERASED_TO_ACTOR]], %0) : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> @owned String
+// CHECK-NEXT: hop_to_executor [[CONTEXT_ISOLATION]]
+// CHECK: [[ISOLATION_ERASED_TO_ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
+// CHECK-NEXT: [[FN_WITNESS:%.*]] = witness_method $T, #P.fn : <Self where Self : P> (Self) -> () async -> () : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> ()
+// CHECK-NEXT: {{.*}} = apply [[FN_WITNESS]]<T>([[ISOLATION_ERASED_TO_ACTOR]], %0) : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> ()
+// CHECK: } // end sil function '$s9witnesses19testGenericExecutor1tyx_tYaAA1PRzlF'
+func testGenericExecutor<T: P>(t: T) async {
+  _ = await t.prop
+  _ = await t.fn()
+}
+
+actor Test {
+  // CHECK-LABEL: sil hidden [ossa] @$s9witnesses4TestC4test1tyx_tYaAA1PRzlF : $@convention(method) @async <T where T : P> (@in_guaranteed T, @sil_isolated @guaranteed Test) -> ()
+  // CHECK: bb0(%0 : $*T, [[ACTOR:%.*]] : @guaranteed $Test):
+  // CHECK: hop_to_executor [[ACTOR]]
+  // CHECK-NEXT: [[ACTOR_COPY:%.*]] = copy_value [[ACTOR]]
+  // CHECK-NEXT: [[ERASED_TO_ACTOR:%.*]] = init_existential_ref [[ACTOR_COPY]] : $Test : $Test, $any Actor
+  // CHECK-NEXT: [[CONTEXT_ISOLATION:%.*]] = enum $Optional<any Actor>, #Optional.some!enumelt, [[ERASED_TO_ACTOR]]
+  // CHECK-NEXT: [[PROP_WITNESS:%.*]] = witness_method $T, #P.prop!getter : <Self where Self : P> (Self) -> () async -> String : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> @owned String
+  // CHECK-NEXT: {{.*}} = apply [[PROP_WITNESS]]<T>([[CONTEXT_ISOLATION]], %0) : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> @owned String
+  // CHECK: hop_to_executor [[ACTOR]]
+  // CHECK: [[ACTOR_COPY:%.*]] = copy_value [[ACTOR]]
+  // CHECK-NEXT: [[ERASED_TO_ACTOR:%.*]] = init_existential_ref [[ACTOR_COPY]] : $Test : $Test, $any Actor
+  // CHECK-NEXT: [[CONTEXT_ISOLATION:%.*]] = enum $Optional<any Actor>, #Optional.some!enumelt, [[ERASED_TO_ACTOR]]
+  // CHECK-NEXT: [[FN_WITNESS:%.*]] = witness_method $T, #P.fn : <Self where Self : P> (Self) -> () async -> () : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> ()
+  // CHECK-NEXT: {{.*}} = apply [[FN_WITNESS]]<T>([[CONTEXT_ISOLATION]], %0) : $@convention(witness_method: P) @async <τ_0_0 where τ_0_0 : P> (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed τ_0_0) -> ()
+  // CHECK: } // end sil function '$s9witnesses4TestC4test1tyx_tYaAA1PRzlF'
+  func test<T: P>(t: T) async {
+    _ = await t.prop
+    _ = await t.fn()
+  }
+}
+
+// CHECK-LABEL: sil hidden [ossa] @$s9witnesses14testDirectCall1syAA1SV_tYaF : $@convention(thin) @async (S) -> ()
+// CHECK: [[MAIN_ACTOR_TYPE:%.*]] = metatype $@thick MainActor.Type
+// CHECK: [[MAIN_ACTOR:%.*]] = apply {{.*}}([[MAIN_ACTOR_TYPE]]) : $@convention(method) (@thick MainActor.Type) -> @owned MainActor
+// CHECK-NEXT: [[BORROWED_MAIN_ACTOR:%.*]] = begin_borrow [[MAIN_ACTOR]]
+// CHECK-NEXT: hop_to_executor [[BORROWED_MAIN_ACTOR]]
+// CHECK-NEXT: [[MAIN_ACTOR_COPY:%.*]] = copy_value [[BORROWED_MAIN_ACTOR]]
+// CHECK-NEXT: [[ERASED_TO_ACTOR:%.*]] = init_existential_ref [[MAIN_ACTOR_COPY]] : $MainActor : $MainActor, $any Actor
+// CHECK-NEXT: [[CONTEXT_ISOLATION:%.*]] = enum $Optional<any Actor>, #Optional.some!enumelt, [[ERASED_TO_ACTOR]]
+// CHECK: [[PROP_REF:%.*]] = function_ref @$s9witnesses1SV4propSSvg : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, S) -> @owned String
+// CHECK-NEXT: {{.*}} = apply [[PROP_REF]]([[CONTEXT_ISOLATION]], %0) : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, S) -> @owned String
+// CHECK: hop_to_executor [[BORROWED_MAIN_ACTOR]]
+// CHECK: [[MAIN_ACTOR_COPY:%.*]] = copy_value [[BORROWED_MAIN_ACTOR]]
+// CHECK-NEXT: [[ERASED_TO_ACTOR:%.*]] = init_existential_ref [[MAIN_ACTOR_COPY]] : $MainActor : $MainActor, $any Actor
+// CHECK-NEXT: [[CONTEXT_ISOLATION:%.*]] = enum $Optional<any Actor>, #Optional.some!enumelt, [[ERASED_TO_ACTOR]]
+// CHECK: [[FN_REF:%.*]] = function_ref @$s9witnesses1SV2fnyyYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, S) -> ()
+// CHECK-NEXT: {{.*}} = apply [[FN_REF]]([[CONTEXT_ISOLATION]], %0) : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, S) -> ()
+// CHECK: } // end sil function '$s9witnesses14testDirectCall1syAA1SV_tYaF'
+@MainActor
+func testDirectCall(s: S) async {
+  _ = await s.prop
+  _ = await s.fn()
+}