[6.2][Concurrency] SE-0461: Extend nonisolated(nonsending) inference to …

lib/Sema/TypeCheckType.cpp

@@ -4280,8 +4280,15 @@ NeverNullType TypeResolver::resolveASTFunctionType(
     if (!repr->isInvalid())
       isolation = FunctionTypeIsolation::forNonIsolated();
   } else if (!getWithoutClaiming<CallerIsolatedTypeRepr>(attrs)) {
-    if (ctx.LangOpts.getFeatureState(Feature::NonisolatedNonsendingByDefault)
-            .isEnabledForMigration()) {
+    // Infer async function type as `nonisolated(nonsending)` if there is
+    // no `@concurrent` or `nonisolated(nonsending)` attribute and isolation
+    // is nonisolated.
+    if (ctx.LangOpts.hasFeature(Feature::NonisolatedNonsendingByDefault) &&
+        repr->isAsync() && isolation.isNonIsolated()) {
+      isolation = FunctionTypeIsolation::forNonIsolatedCaller();
+    } else if (ctx.LangOpts
+                   .getFeatureState(Feature::NonisolatedNonsendingByDefault)
+                   .isEnabledForMigration()) {
       // Diagnose only in the interface stage, which is run once.
       if (inStage(TypeResolutionStage::Interface)) {
         warnAboutNewNonisolatedAsyncExecutionBehavior(ctx, repr, isolation);

test/Concurrency/attr_execution/attr_execution.swift

@@ -14,3 +14,69 @@ func concurrentTest() async {}
 // CHECK: sil hidden [ossa] @$s14attr_execution10callerTestyyYaF : $@convention(thin) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> () {
 nonisolated(nonsending)
 func callerTest() async {}
+
+struct Test {
+  // CHECK-LABEL: // closure #1 in variable initialization expression of Test.x
+  // CHECK: // Isolation: caller_isolation_inheriting
+  // CHECK: sil private [ossa] @$s14attr_execution4TestV1xyyYaYCcvpfiyyYaYCcfU_ : $@convention(thin) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()
+  var x: () async -> Void = {}
+
+  // CHECK-LABEL: // Test.test()
+  // CHECK: // Isolation: caller_isolation_inheriting
+  // CHECK: sil hidden [ossa] @$s14attr_execution4TestV4testyyYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed Test) -> ()
+  // CHECK: bb0([[ISOLATION:%.*]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] : @guaranteed $Test)
+  // CHECK: [[X_REF:%.*]] = struct_extract %1, #Test.x
+  // CHECK: [[X_REF_COPY:%.]] = copy_value [[X_REF]]
+  // CHECK: [[BORROWED_X:%.*]] = begin_borrow [[X_REF_COPY]]
+  // CHECK: apply [[BORROWED_X]]([[ISOLATION]]) : $@async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()
+  // CHECK: } // end sil function '$s14attr_execution4TestV4testyyYaF'
+  func test() async {
+    await x()
+  }
+
+  // CHECK-LABEL: // Test.testParam(fn:)
+  // CHECK: // Isolation: caller_isolation_inheriting
+  // CHECK: sil hidden [ossa] @$s14attr_execution4TestV9testParam2fnyyyYaYCcSg_tYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @guaranteed Optional<@async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()>, @guaranteed Test) -> ()
+  // CHECK: bb0([[ISOLATION:%.*]] : @guaranteed $Optional<any Actor>, [[OPT_FN:%.*]] : @guaranteed $Optional<@async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()>, [[SELF:%.*]] : @guaranteed $Test)
+  // CHECK: bb1([[FN:%.*]] : @owned $@async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ())
+  // CHECK: [[BORROWED_FN:%.*]] = begin_borrow [[FN]]
+  // CHECK: apply [[BORROWED_FN]]([[ISOLATION]]) : $@async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()  
+  // CHECK: } // end sil function '$s14attr_execution4TestV9testParam2fnyyyYaYCcSg_tYaF'
+  func testParam(fn: (() async -> Void)?) async {
+    await fn?()
+  }
+}
+
+// CHECK-LABEL: // testLocal()
+// CHECK: // Isolation: caller_isolation_inheriting
+// CHECK: sil hidden [ossa] @$s14attr_execution9testLocalyyYaF : $@convention(thin) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> () {
+// CHECK: bb0([[ISOLATION:%.*]] : @guaranteed $Optional<any Actor>)
+// CHECK: bb1([[FN:%.*]] : @owned $@async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ())
+// CHECK: [[BORROWED_FN:%.*]] = begin_borrow [[FN]]
+// CHECK: apply [[BORROWED_FN]]([[ISOLATION]]) : $@async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()
+// CHECK: } // end sil function '$s14attr_execution9testLocalyyYaF'
+func testLocal() async {
+  let fn: (() async -> Void)? = nil
+  await fn?()
+}
+
+// CHECK-LABEL: // takesClosure(fn:)
+// CHECK: // Isolation: unspecified
+// CHECK: sil hidden [ossa] @$s14attr_execution12takesClosure2fnyyyYaYCXE_tF : $@convention(thin) (@guaranteed @noescape @async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()) -> ()
+func takesClosure(fn: () async -> Void) {
+}
+
+// CHECK-LABEL: sil hidden [ossa] @$s14attr_execution11testClosureyyF : $@convention(thin) () -> ()
+// CHECK:  [[CLOSURE:%.*]] = function_ref @$s14attr_execution11testClosureyyFyyYaYCXEfU_ : $@convention(thin) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()
+// CHECK:  [[THUNKED_CLOSURE:%.*]] = thin_to_thick_function %0 to $@noescape @async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()
+// CHECK:  [[TAKES_CLOSURE:%.*]] = function_ref @$s14attr_execution12takesClosure2fnyyyYaYCXE_tF : $@convention(thin) (@guaranteed @noescape @async @callee_guaranteed (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()) -> ()
+// CHECK:  apply [[TAKES_CLOSURE]]([[THUNKED_CLOSURE]])
+// CHECK: } // end sil function '$s14attr_execution11testClosureyyF'
+
+// CHECK-LABEL: // closure #1 in testClosure()
+// CHECK: // Isolation: caller_isolation_inheriting
+// CHECK: sil private [ossa] @$s14attr_execution11testClosureyyFyyYaYCXEfU_ : $@convention(thin) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>) -> ()
+func testClosure() {
+  takesClosure {
+  }
+}

test/Concurrency/attr_execution/nonisolated_nonsending_by_default.swift

@@ -0,0 +1,10 @@
+// RUN: %target-typecheck-verify-swift -swift-version 6 -enable-upcoming-feature NonisolatedNonsendingByDefault %s
+
+// REQUIRES: swift_feature_NonisolatedNonsendingByDefault
+
+func testCasts() {
+  let defaultedType = (() async -> ()).self
+  _ = defaultedType as (@concurrent () async -> ()).Type
+  // expected-error@-1 {{cannot convert value of type '(nonisolated(nonsending) () async -> ()).Type' to type '(() async -> ()).Type' in coercion}}
+  _ = defaultedType as (nonisolated(nonsending) () async -> ()).Type // Ok
+}