Fix getDirectlyInheritedNominalTypeDecls

include/swift/AST/TypeCheckRequests.h

@@ -334,7 +334,8 @@ class RequirementSignatureRequest :
   friend SimpleRequest;
 
   // Evaluation.
-  llvm::Expected<ArrayRef<Requirement>> evaluate(Evaluator &evaluator, ProtocolDecl *proto) const;
+  llvm::Expected<ArrayRef<Requirement>> evaluate(Evaluator &evaluator,
+                                                 ProtocolDecl *proto) const;
 
 public:
   // Separate caching.

lib/AST/NameLookup.cpp

@@ -2435,6 +2435,27 @@ swift::getDirectlyInheritedNominalTypeDecls(
   // FIXME: Refactor SelfBoundsFromWhereClauseRequest to dig out
   // the source location.
   SourceLoc loc = SourceLoc();
+
+  // For a deserialized protocol, the where clause isn't going to tell us
+  // anything. Ask the requirement signature instead.
+  if (protoDecl->wasDeserialized()) {
+    auto protoSelfTy = protoDecl->getSelfInterfaceType();
+    for (auto &req : protoDecl->getRequirementSignature()) {
+      // Dig out a conformance requirement...
+      if (req.getKind() != RequirementKind::Conformance)
+        continue;
+
+      // constraining Self.
+      if (!req.getFirstType()->isEqual(protoSelfTy))
+        continue;
+
+      result.emplace_back(
+          loc, req.getSecondType()->castTo<ProtocolType>()->getDecl());
+    }
+    return result;
+  }
+
+  // Else we have access to this information on the where clause.
   auto selfBounds = getSelfBoundsFromWhereClause(decl);
   anyObject |= selfBounds.anyObject;
 

test/Interpreter/Inputs/dynamic_replacement_protocol_self_orig.swift

@@ -0,0 +1,56 @@
+protocol View {
+  associatedtype Body: View
+
+  var body: Self.Body { get }
+}
+
+extension Never: View {
+  typealias Body = Never
+
+  var body: Self.Body { fatalError() }
+}
+
+struct AnyView: View {
+  var body: Never { fatalError() }
+}
+
+protocol ViewModelRenderable {
+  var view: AnyView { get }
+}
+
+extension ViewModelRenderable where Self: SectionModel {
+  static func view<Model, MyView: SectionViewModelView>(for model: Model, ofType: MyView.Type) -> AnyView where Model == MyView.BodyViewModel {
+    fatalError()
+  }
+}
+
+protocol SectionViewModelView where Self: View {
+  associatedtype BodyViewModel: SectionModel
+
+  init(bodyViewModel: BodyViewModel)
+}
+
+public protocol SectionModel: Codable {
+  var sectionName: String { get }
+}
+
+extension SectionModel {
+  public var sectionName: String {
+    "Hello world!"
+  }
+}
+
+struct NewUserModel: SectionModel {
+}
+
+extension NewUserModel: ViewModelRenderable {
+  var view: AnyView { Self.view(for: self, ofType: NewUserView.self) }
+}
+
+struct NewUserView: SectionViewModelView {
+  var bodyViewModel: NewUserModel = .init()
+
+  var body: Never {
+    fatalError()
+  }
+}

test/Interpreter/dynamic_replacement_protocol_self.swift

@@ -0,0 +1,22 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift-dylib(%t/%target-library-name(TestModuleLinking)) -module-name TestModuleLinking -emit-module -emit-module-path %t/TestModuleLinking.swiftmodule -swift-version 5 %S/Inputs/dynamic_replacement_protocol_self_orig.swift -Xfrontend -enable-private-imports -Xfrontend -enable-implicit-dynamic
+// RUN: %target-build-swift -I%t -L%t -lTestModuleLinking -o %t/main %target-rpath(%t) %s -swift-version 5
+// RUN: %target-codesign %t/main %t/%target-library-name(TestModuleLinking)
+// RUN: %target-run %t/main %t/%target-library-name(TestModuleLinking) %t/%target-library-name(TestModuleLinking)
+
+// N.B. We're not actually executing anything here - all we care about is
+// if the linker is content.
+
+// REQUIRES: executable_test
+
+// UNSUPPORTED: swift_test_mode_optimize_none_with_implicit_dynamic
+
+@_private(sourceFile: "dynamic_replacement_protocol_self_orig.swift") import TestModuleLinking
+
+extension NewUserModel {
+  @_dynamicReplacement(for: view) private var __preview__view: AnyView {
+    Self.view(for: self, ofType: NewUserView.self)
+  }
+}
+
+typealias NewUserModel = TestModuleLinking.NewUserModel