[Concurrency] Fix circular reference on isolation propagation.

Author: DougGregor

lib/Sema/TypeCheckConcurrency.cpp

@@ -1035,6 +1035,9 @@ static Optional<ActorIsolation> getIsolationFromWitnessedRequirements(
   if (!idc)
     return None;
 
+  if (dc->getSelfProtocolDecl())
+    return None;
+
   // Walk through each of the conformances in this context, collecting any
   // requirements that have actor isolation.
   auto conformances = evaluateOrDefault(
@@ -1167,6 +1170,12 @@ ActorIsolation ActorIsolationRequest::evaluate(
     }
   }
 
+  // If this is an accessor, use the actor isolation of its storage
+  // declaration.
+  if (auto accessor = dyn_cast<AccessorDecl>(value)) {
+    return getActorIsolation(accessor->getStorage());
+  }
+
   // If the declaration witnesses a protocol requirement that is isolated,
   // use that.
   if (auto witnessedIsolation = getIsolationFromWitnessedRequirements(value)) {
@@ -1194,14 +1203,6 @@ ActorIsolation ActorIsolationRequest::evaluate(
     }
   }
 
-  // If this is an accessor, use the actor isolation of its storage
-  // declaration.
-  if (auto accessor = dyn_cast<AccessorDecl>(value)) {
-    auto storageIsolation = getActorIsolation(accessor->getStorage());
-    if (!storageIsolation.isUnspecified())
-      return inferredIsolation(storageIsolation);
-  }
-
   // If the declaration is in an extension that has one of the isolation
   // attributes, use that.
   if (auto ext = dyn_cast<ExtensionDecl>(value->getDeclContext())) {

test/Incremental/Verifier/single-file-private/AnyObject.swift

@@ -72,3 +72,17 @@ func lookupOnAnyObject(object: AnyObject) { // expected-provides {{lookupOnAnyOb
 // expected-member {{Swift.CVarArg.someMethod}}
 // expected-member {{Swift.CustomStringConvertible.someMethod}}
 // expected-member {{Swift.CustomDebugStringConvertible.someMethod}}
+// expected-member {{Swift.Equatable.someMember}}
+// expected-member{{Swift.CustomDebugStringConvertible.init}}
+// expected-member{{Swift.CVarArg.someMember}}
+// expected-member{{Foundation._KeyValueCodingAndObservingPublishing.someMember}}
+// expected-member{{Swift.Equatable.init}}
+// expected-member{{Swift.Hashable.init}}
+// expected-member{{Swift.CVarArg.init}}
+// expected-member{{Foundation._KeyValueCodingAndObserving.someMember}}
+// expected-member{{Foundation._KeyValueCodingAndObservingPublishing.init}}
+// expected-member{{Swift.CustomDebugStringConvertible.someMember}}
+// expected-member{{Swift.CustomStringConvertible.someMember}}
+// expected-member{{Swift.CustomStringConvertible.init}}
+// expected-member{{Swift.Hashable.someMember}}
+// expected-member{{Foundation._KeyValueCodingAndObserving.init}}

test/decl/class/circular_inheritance.swift

@@ -4,14 +4,14 @@
 // RUN: not %target-swift-frontend -typecheck -debug-cycles %s -build-request-dependency-graph -output-request-graphviz %t.dot -stats-output-dir %t/stats-dir 2> %t.cycles
 // RUN: %FileCheck -check-prefix CHECK-DOT %s < %t.dot
 
-class Left // expected-error {{'Left' inherits from itself}} expected-note {{through reference here}}
+class Left // expected-error {{'Left' inherits from itself}} expected-note 2{{through reference here}}
     : Right.Hand { // expected-note {{through reference here}}
-  class Hand {}
+  class Hand {}  // expected-note {{through reference here}}
 }
 
-class Right // expected-note {{through reference here}} expected-note{{class 'Right' declared here}}
+class Right // expected-note 2 {{through reference here}} expected-note{{class 'Right' declared here}}
   : Left.Hand { // expected-note {{through reference here}}
-  class Hand {}
+  class Hand {}  // expected-error {{circular reference}}
 }
 
 class C : B { } // expected-error{{'C' inherits from itself}}
@@ -30,15 +30,15 @@ class Outer {
   class Inner : Outer {}
 }
 
-class Outer2 // expected-error {{'Outer2' inherits from itself}} expected-note {{through reference here}}
+class Outer2 // expected-error {{'Outer2' inherits from itself}} expected-note 2 {{through reference here}}
     : Outer2.Inner { // expected-note {{through reference here}}
 
-  class Inner {}
+  class Inner {} // expected-error{{circular reference}}
 }
 
-class Outer3 // expected-error {{'Outer3' inherits from itself}} expected-note {{through reference here}}
+class Outer3 // expected-error {{'Outer3' inherits from itself}} expected-note 2 {{through reference here}}
     : Outer3.Inner<Int> { // expected-note {{through reference here}}
-  class Inner<T> {}
+  class Inner<T> {} // expected-error{{circular reference}}
 }
 
 // CHECK-DOT: digraph Dependencies