Print isolated conformances in textual interfaces

Author: DougGregor

lib/AST/ASTPrinter.cpp

@@ -2924,6 +2924,18 @@ void PrintAST::printInherited(const Decl *decl) {
           Printer << "@unsafe ";
         break;
       }
+
+      if (auto globalActor = inherited.getGlobalActorIsolationType()) {
+        TypeLoc globalActorTL(globalActor->getTypeRepr(),
+                              globalActor->getInstanceType());
+        Printer << "@";
+        printTypeLoc(globalActorTL);
+        Printer << " ";
+      }
+
+      if (inherited.isNonisolated())
+        Printer << "nonisolated ";
+
       if (inherited.isSuppressed())
         Printer << "~";
     });

test/ModuleInterface/isolated_conformance.swift

@@ -0,0 +1,16 @@
+// RUN: %target-swift-frontend -typecheck -swift-version 6 -enable-library-evolution -module-name isolated_conformance -enable-experimental-feature IsolatedConformances -emit-module-interface-path - %s | %FileCheck %s
+
+// REQUIRES: swift_feature_IsolatedConformances
+// REQUIRES: concurrency
+
+public protocol MyProtocol {
+  func f()
+}
+
+@MainActor
+public class MyClass { }
+
+// CHECK: extension isolated_conformance.MyClass : @MainActor isolated_conformance.MyProtocol {
+extension MyClass: @MainActor MyProtocol {
+  @MainActor public func f() { }
+}