Merge pull request swiftlang#38500 from slavapestov/actor-isolation-cycle

Sema: Kick off ActorIsolationRequest after checking conformances to avoid cycles

Author: slavapestov

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -1668,7 +1668,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       // Force some requests, which can produce diagnostics.
 
       // Check redeclaration.
-      (void) evaluateOrDefault(decl->getASTContext().evaluator,
+      (void) evaluateOrDefault(Context.evaluator,
                                CheckRedeclarationRequest{VD}, {});
 
       // Compute access level.
@@ -1682,8 +1682,11 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       (void) VD->isObjC();
       (void) VD->isDynamic();
 
-      // Check for actor isolation.
-      (void)getActorIsolation(VD);
+      // Check for actor isolation of top-level and local declarations.
+      // Declarations inside types are handled in checkConformancesInContext()
+      // to avoid cycles involving associated type inference.
+      if (!VD->getDeclContext()->isTypeContext())
+        (void) getActorIsolation(VD);
 
       // If this is a member of a nominal type, don't allow it to have a name of
       // "Type" or "Protocol" since we reserve the X.Type and X.Protocol
@@ -1694,7 +1697,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
            VD->getName().isSimpleName(Context.Id_Protocol)) &&
           VD->getNameLoc().isValid() &&
           Context.SourceMgr.extractText({VD->getNameLoc(), 1}) != "`") {
-        auto &DE = getASTContext().Diags;
+        auto &DE = Context.Diags;
         DE.diagnose(VD->getNameLoc(), diag::reserved_member_name,
                     VD->getName(), VD->getBaseIdentifier().str());
         DE.diagnose(VD->getNameLoc(), diag::backticks_to_escape)

lib/Sema/TypeCheckProtocol.cpp

@@ -5936,6 +5936,13 @@ void TypeChecker::checkConformancesInContext(IterableDeclContext *idc) {
   // Check all conformances.
   groupChecker.checkAllConformances();
 
+  // Check actor isolation.
+  for (auto *member : idc->getMembers()) {
+    if (auto *valueDecl = dyn_cast<ValueDecl>(member)) {
+      (void)getActorIsolation(valueDecl);
+    }
+  }
+
   if (Context.TypeCheckerOpts.DebugGenericSignatures &&
       !conformances.empty()) {
     // Now that they're filled out, print out information about the conformances

test/Concurrency/actor_isolation_cycle.swift

@@ -0,0 +1,11 @@
+// RUN: %target-typecheck-verify-swift
+
+public protocol P {
+  associatedtype T
+  @MainActor func f(_: T)
+  @MainActor func g(_: T)
+}
+public struct S : P {
+  public func g(_: Int) {}
+  public func f(_: T) {}
+}

test/ModuleInterface/actor_isolation.swift

@@ -68,6 +68,18 @@ public class C7 { }
 @available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
 extension C7: UnsafeSendable { }
 
+@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+public protocol P2 {
+  @SomeGlobalActor func method()
+}
+
+@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+// CHECK: class {{(Test.)?}}C8 : {{(Test.)?}}P2 {
+public class C8 : P2 {
+  // CHECK: @{{(Test.)?}}SomeGlobalActor public func method()
+  public func method() {}
+}
+
 // FIXME: Work around a bug where module printing depends on the "synthesized"
 // bit in conformances which is not serialized and not present in the textual
 // form.