[Concurrency] Infer isolation of methods that override caller isolated @objc async handlers to be `@concurrent

This is behavior pre-SE-0461 which is the safest option instead
of inferring `nonisolated(nonsending)` and changing the calling
convention and foregoing Sendable checking.

(cherry picked from commit c25d2fa)

Author: xedin

lib/Sema/TypeCheckConcurrency.cpp

@@ -5845,6 +5845,22 @@ computeDefaultInferredActorIsolation(ValueDecl *value) {
     // Use the overridden decl's isolation as the default isolation for this
     // decl.
     auto isolation = getOverriddenIsolationFor(value);
+
+    // If this is an override of an async completion handler, mark
+    // it `@concurrent` instead of inferring `nonisolated(nonsending)`
+    // to preserve pre-SE-0461 behavior.
+    if (isolation.isCallerIsolationInheriting() &&
+        overriddenValue->hasClangNode()) {
+      if (auto *AFD = dyn_cast<AbstractFunctionDecl>(overriddenValue)) {
+        if (AFD->getForeignAsyncConvention()) {
+          return {{ActorIsolation::forNonisolated(/*unsafe=*/false),
+                   IsolationSource(overriddenValue, IsolationSource::Override)},
+                  overriddenValue,
+                  isolation};
+        }
+      }
+    }
+
     return {{isolation,
              IsolationSource(overriddenValue, IsolationSource::Override)},
             overriddenValue,

test/Concurrency/attr_execution_objc.swift renamed to test/Concurrency/nonisolated_nonsending_objc_async_by_default.swift

@@ -29,6 +29,14 @@ MAIN_ACTOR
 
 //--- main.swift
 
+class OverrideTest1 : Test {
+  override func load() async {}
+}
+
+class OverrideTest2 : TestIsolated {
+  override func load() async {}
+}
+
 func test(t: Test, i: TestIsolated) async throws {
   let fn = t.load // nonisolated(nonsending) () async -> Void
 
@@ -39,3 +47,10 @@ func test(t: Test, i: TestIsolated) async throws {
   let _: () -> Void = isolatedFn
   // expected-error@-1 {{invalid conversion from 'async' function of type '@MainActor @Sendable () async -> Void' to synchronous function type '() -> Void'}}
 }
+
+func testOverrides(o1: OverrideTest1, o2: OverrideTest2) {
+  let _: () -> Void = o1.load
+  // expected-error@-1 {{invalid conversion from 'async' function of type '() async -> ()' to synchronous function type '() -> Void'}}
+  let _: () -> Void = o2.load
+  // expected-error@-1 {{invalid conversion from 'async' function of type '@MainActor @Sendable () async -> ()' to synchronous function type '() -> Void'}}
+}

test/SILGen/objc_async_from_swift.swift

@@ -108,85 +108,93 @@ extension SlowServer: NativelySlowServing {}
 class SlowServerlet: SlowServer {
     // Native Function
     //
-    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC011doSomethingE8NullablyySiSSYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed String, @guaranteed SlowServerlet) -> Int {
-    // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>
+    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC011doSomethingE8NullablyySiSSYaF : $@convention(method) @async (@guaranteed String, @guaranteed SlowServerlet) -> Int
+    // CHECK-NOT: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>
+    // CHECK: [[ACTOR:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
     // CHECK:   hop_to_executor [[ACTOR]]
     // CHECK:   // end sil function '$s21objc_async_from_swift13SlowServerletC011doSomethingE8NullablyySiSSYaF'
 
     // @objc thunk closure
     //
     // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC011doSomethingE8NullablyySiSSYaFyyYacfU_To : $@convention(thin) @Sendable @async (NSString, Optional<@convention(block) @Sendable (Int) -> ()>, SlowServerlet) -> () {
-    // CHECK: [[ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
-    // CHECK: [[FUNC:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC011doSomethingE8NullablyySiSSYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed String, @guaranteed SlowServerlet) -> Int
-    // CHECK: apply [[FUNC]]([[ACTOR]],
+    // CHECK: [[STR_ARG:%.*]] = begin_borrow {{.*}} : $String
+    // CHECK: [[SELF:%.*]] = begin_borrow {{.*}} : $SlowServerlet
+    // CHECK: [[FUNC:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC011doSomethingE8NullablyySiSSYaF : $@convention(method) @async (@guaranteed String, @guaranteed SlowServerlet) -> Int
+    // CHECK: apply [[FUNC]]([[STR_ARG]], [[SELF]])
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC011doSomethingE8NullablyySiSSYaFyyYacfU_To'
     override func doSomethingSlowNullably(_: String) async -> Int {
         return 0
     }
 
     // Native function.
     //
-    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC18findAnswerNullablyyS2SYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed String, @guaranteed SlowServerlet) -> @owned String {
-    // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
-    // CHECK:   hop_to_executor [[ACTOR]]
+    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC18findAnswerNullablyyS2SYaF : $@convention(method) @async (@guaranteed String, @guaranteed SlowServerlet) -> @owned String
+    // CHECK-NOT: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>
+    // CHECK: [[ACTOR:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
+    // CHECK-NEXT: hop_to_executor [[ACTOR]]
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC18findAnswerNullablyyS2SYaF'
 
     // @objc closure thunk
     // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC18findAnswerNullablyyS2SYaFyyYacfU_To : $@convention(thin) @Sendable @async (NSString, Optional<@convention(block) @Sendable (NSString) -> ()>, SlowServerlet) -> () {
-    // CHECK: [[ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
-    // CHECK: [[FUNC:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC18findAnswerNullablyyS2SYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed String, @guaranteed SlowServerlet) -> @owned String
-    // CHECK: apply [[FUNC]]([[ACTOR]],
+    // CHECK: [[STR_ARG:%.*]] = begin_borrow {{.*}} : $String
+    // CHECK: [[SELF:%.*]] = begin_borrow {{.*}} : $SlowServerlet
+    // CHECK: [[FUNC:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC18findAnswerNullablyyS2SYaF : $@convention(method) @async (@guaranteed String, @guaranteed SlowServerlet) -> @owned String
+    // CHECK: apply [[FUNC]]([[STR_ARG]], [[SELF]])
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC18findAnswerNullablyyS2SYaFyyYacfU_To'
     override func findAnswerNullably(_ x: String) async -> String {
         return x
     }
 
     // Native
     //
-    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC28doSomethingDangerousNullablyyS2SYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed String, @guaranteed SlowServerlet) -> (@owned String, @error any Error) {
-    // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
-    // CHECK:   hop_to_executor [[ACTOR]]
+    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC28doSomethingDangerousNullablyyS2SYaKF : $@convention(method) @async (@guaranteed String, @guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK-NOT: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
+    // CHECK: [[ACTOR:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
+    // CHECK-NEXT: hop_to_executor [[ACTOR]]
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC28doSomethingDangerousNullablyyS2SYaKF'
 
     // @objc thunk closure
     //
     // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC28doSomethingDangerousNullablyyS2SYaKFyyYacfU_To : $@convention(thin) @Sendable @async (NSString, Optional<@convention(block) @Sendable (Optional<NSString>, Optional<NSError>) -> ()>, SlowServerlet) -> () {
-    // CHECK: [[ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
-    // CHECK: [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC28doSomethingDangerousNullablyyS2SYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed String, @guaranteed SlowServerlet) -> (@owned String, @error any Error)
-    // CHECK: apply [[NATIVE]]([[ACTOR]],
+    // CHECK: [[STR_ARG:%.*]] = begin_borrow {{.*}} : $String
+    // CHECK: [[SELF:%.*]] = begin_borrow {{.*}} : $SlowServerlet
+    // CHECK: [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC28doSomethingDangerousNullablyyS2SYaKF : $@convention(method) @async (@guaranteed String, @guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK: apply [[NATIVE]]([[STR_ARG]], [[SELF]])
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC28doSomethingDangerousNullablyyS2SYaKFyyYacfU_To'
     override func doSomethingDangerousNullably(_ x: String) async throws -> String {
         return x
     }
 
     // Native
     //
-    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC30doSomethingUnspecifiedNullablySSyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @error any Error) {
-    // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
-    // CHECK:   hop_to_executor [[ACTOR]]
+    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC30doSomethingUnspecifiedNullablySSyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK-NOT: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
+    // CHECK: [[ACTOR:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
+    // CHECK-NEXT: hop_to_executor [[ACTOR]]
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC30doSomethingUnspecifiedNullablySSyYaKF'
 
     // @objc closure thunk
     // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC30doSomethingUnspecifiedNullablySSyYaKFyyYacfU_To : $@convention(thin) @Sendable @async (Optional<@convention(block) @Sendable (Optional<NSString>, Optional<NSError>) -> ()>, SlowServerlet) -> () {
-    // CHECK: [[ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
-    // CHECK: [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC30doSomethingUnspecifiedNullablySSyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @error any Error)
-    // CHECK: apply [[NATIVE]]([[ACTOR]],
+    // CHECK: [[SELF:%.*]] = begin_borrow {{.*}} : $SlowServerlet
+    // CHECK: [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC30doSomethingUnspecifiedNullablySSyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK: apply [[NATIVE]]([[SELF]])
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC30doSomethingUnspecifiedNullablySSyYaKFyyYacfU_To'
     override func doSomethingUnspecifiedNullably() async throws -> String {
       fatalError()
     }
 
     // Native
     //
-    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC17doSomethingFlaggySSyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @error any Error) {
-    // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
-    // CHECK:   hop_to_executor [[ACTOR]]
-    //
+    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC17doSomethingFlaggySSyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK-NOT: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
+    // CHECK: [[ACTOR:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
+    // CHECK-NEXT: hop_to_executor [[ACTOR]]
+
     // @objc thunk closure
-    // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC17doSomethingFlaggySSyYaKFyyYacfU_To : $@convention(thin) @Sendable @async (@convention(block) @Sendable (Bool, Optional<NSString>, Optional<NSError>) -> (), SlowServerlet) -> () {
-    // CHECK:   [[ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
-    // CHECK:   [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC17doSomethingFlaggySSyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @error any Error)
-    // CHECK:   try_apply [[NATIVE]]([[ACTOR]], {{.*}}, normal [[NORMAL_BB:bb[0-9]+]], error [[ERROR_BB:bb[0-9]+]]
+    // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC17doSomethingFlaggySSyYaKFyyYacfU_To : $@convention(thin) @Sendable @async (@convention(block) @Sendable ({{.*}}, Optional<NSString>, Optional<NSError>) -> (), SlowServerlet) -> () {
+    // CHECK: [[SELF:%.*]] = begin_borrow {{.*}} : $SlowServerlet
+    // CHECK:   [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC17doSomethingFlaggySSyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK:   try_apply [[NATIVE]]([[SELF]]) : {{.*}}, normal [[NORMAL_BB:bb[0-9]+]], error [[ERROR_BB:bb[0-9]+]]
     // CHECK: [[NORMAL_BB]]({{.*}}):
     // CHECK:   integer_literal {{.*}}0
     // CHECK: [[ERROR_BB]]({{.*}}):
@@ -198,16 +206,17 @@ class SlowServerlet: SlowServer {
 
     // Native
     //
-    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC21doSomethingZeroFlaggySSyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @error any Error) {
-    // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
-    // CHECK:   hop_to_executor [[ACTOR]]
+    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC21doSomethingZeroFlaggySSyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK-NOT: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
+    // CHECK: [[ACTOR:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
+    // CHECK-NEXT: hop_to_executor [[ACTOR]]
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC21doSomethingZeroFlaggySSyYaKF'
     //
     // @objc thunk closure
-    // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC21doSomethingZeroFlaggySSyYaKFyyYacfU_To : $@convention(thin) @Sendable @async (@convention(block) @Sendable (Optional<NSString>, Bool, Optional<NSError>) -> (), SlowServerlet) -> () {
-    // CHECK:    [[ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
-    // CHECK:    [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC21doSomethingZeroFlaggySSyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @error any Error)
-    // CHECK:    try_apply [[NATIVE]]([[ACTOR]], {{.*}}, normal [[NORMAL_BB:bb[0-9]+]], error [[ERROR_BB:bb[0-9]+]]
+    // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC21doSomethingZeroFlaggySSyYaKFyyYacfU_To : $@convention(thin) @Sendable @async (@convention(block) @Sendable (Optional<NSString>, {{.*}}, Optional<NSError>) -> (), SlowServerlet) -> () {
+    // CHECK: [[SELF:%.*]] = begin_borrow {{.*}} : $SlowServerlet
+    // CHECK:    [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC21doSomethingZeroFlaggySSyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @error any Error)
+    // CHECK:    try_apply [[NATIVE]]([[SELF]]) : {{.*}}, normal [[NORMAL_BB:bb[0-9]+]], error [[ERROR_BB:bb[0-9]+]]
     // CHECK:  [[NORMAL_BB]]({{.*}}):
     // CHECK:    integer_literal {{.*}}1
     // CHECK:  [[ERROR_BB]]({{.*}}):
@@ -218,15 +227,16 @@ class SlowServerlet: SlowServer {
 
     // Native
     //
-    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC28doSomethingMultiResultFlaggySS_SStyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @owned String, @error any Error) {
-    // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
-    // CHECK:   hop_to_executor [[ACTOR]]
+    // CHECK-LABEL: sil hidden [ossa] @$s21objc_async_from_swift13SlowServerletC28doSomethingMultiResultFlaggySS_SStyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @owned String, @error any Error)
+    // CHECK-NOT: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>,
+    // CHECK: [[ACTOR:%.*]] = enum $Optional<Builtin.Executor>, #Optional.none!enumelt
+    // CHECK-NEXT: hop_to_executor [[ACTOR]]
     // CHECK: } // end sil function '$s21objc_async_from_swift13SlowServerletC28doSomethingMultiResultFlaggySS_SStyYaKF'
     //
-    // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC28doSomethingMultiResultFlaggySS_SStyYaKFyyYacfU_To : $@convention(thin) @Sendable @async (@convention(block) @Sendable (Bool, Optional<NSString>, Optional<NSError>, Optional<NSString>) -> (), SlowServerlet) -> () {
-    // CHECK:   [[ACTOR:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
-    // CHECK:   [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC28doSomethingMultiResultFlaggySS_SStyYaKF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed SlowServerlet) -> (@owned String, @owned String, @error any Error)
-    // CHECK:   try_apply [[NATIVE]]([[ACTOR]], {{.*}}, normal [[NORMAL_BB:bb[0-9]+]], error [[ERROR_BB:bb[0-9]+]]
+    // CHECK-LABEL: sil shared [thunk] [ossa] @$s21objc_async_from_swift13SlowServerletC28doSomethingMultiResultFlaggySS_SStyYaKFyyYacfU_To : $@convention(thin) @Sendable @async (@convention(block) @Sendable ({{.*}}, Optional<NSString>, Optional<NSError>, Optional<NSString>) -> (), SlowServerlet) -> () {
+    // CHECK: [[SELF:%.*]] = begin_borrow {{.*}} : $SlowServerlet
+    // CHECK:   [[NATIVE:%.*]] = function_ref @$s21objc_async_from_swift13SlowServerletC28doSomethingMultiResultFlaggySS_SStyYaKF : $@convention(method) @async (@guaranteed SlowServerlet) -> (@owned String, @owned String, @error any Error)
+    // CHECK:   try_apply [[NATIVE]]([[SELF]]) : {{.*}}, normal [[NORMAL_BB:bb[0-9]+]], error [[ERROR_BB:bb[0-9]+]]
     // CHECK: [[NORMAL_BB]]({{.*}}):
     // CHECK:   integer_literal {{.*}}1
     // CHECK: [[ERROR_BB]]({{.*}}):