[Type checker] Ensure we sort semantic members properly.

When evaluating the semantic members request, we would sort the members
before we return them to ensure a stable ordering for (e.g.) vtable
layout. However, when not in a source file, we would assume that the
resulting members were always sorted. However, they are not always
sorted, because we write the iterative decl contexts directly rather
than writing the semantic members.

Fixes rdar://72833032.

(cherry picked from commit 5426117)

Author: DougGregor

lib/Sema/TypeCheckDecl.cpp

@@ -2557,51 +2557,49 @@ SemanticMembersRequest::evaluate(Evaluator &evaluator,
   auto &Context = dc->getASTContext();
   SmallVector<Decl *, 8> result;
 
-  if (!dc->getParentSourceFile()) {
-    auto members = idc->getMembers();
-    result.append(members.begin(), members.end());
-    return Context.AllocateCopy(result);
-  }
-
-  auto nominal = dyn_cast<NominalTypeDecl>(idc);
-
-  if (nominal) {
-    // We need to add implicit initializers because they
-    // affect vtable layout.
-    TypeChecker::addImplicitConstructors(nominal);
-  }
-
-  // Force any derivable conformances in this context. This ensures that any
-  // synthesized members will approach in the member list.
-  for (auto conformance : idc->getLocalConformances()) {
-    if (conformance->getState() == ProtocolConformanceState::Incomplete &&
-        conformance->getProtocol()->getKnownDerivableProtocolKind())
-      TypeChecker::checkConformance(conformance->getRootNormalConformance());
-  }
-
-  // If the type conforms to Encodable or Decodable, even via an extension,
-  // the CodingKeys enum is synthesized as a member of the type itself.
-  // Force it into existence.
-  if (nominal) {
-    (void) evaluateOrDefault(Context.evaluator,
-                             ResolveImplicitMemberRequest{nominal,
-                                        ImplicitMemberAction::ResolveCodingKeys},
-                             {});
-  }
-
-  // If the decl has a @main attribute, we need to force synthesis of the
-  // $main function.
-  (void) evaluateOrDefault(
-      Context.evaluator,
-      SynthesizeMainFunctionRequest{const_cast<Decl *>(idc->getDecl())},
-      nullptr);
-
-  for (auto *member : idc->getMembers()) {
-    if (auto *var = dyn_cast<VarDecl>(member)) {
-      // The projected storage wrapper ($foo) might have dynamically-dispatched
-      // accessors, so force them to be synthesized.
-      if (var->hasAttachedPropertyWrapper())
-        (void) var->getPropertyWrapperBackingProperty();
+  // Esnure that we add any synthesized members.
+  if (dc->getParentSourceFile()) {
+    auto nominal = dyn_cast<NominalTypeDecl>(idc);
+
+    if (nominal) {
+      // We need to add implicit initializers because they
+      // affect vtable layout.
+      TypeChecker::addImplicitConstructors(nominal);
+    }
+
+    // Force any derivable conformances in this context. This ensures that any
+    // synthesized members will approach in the member list.
+    for (auto conformance : idc->getLocalConformances()) {
+      if (conformance->getState() == ProtocolConformanceState::Incomplete &&
+          conformance->getProtocol()->getKnownDerivableProtocolKind())
+        TypeChecker::checkConformance(conformance->getRootNormalConformance());
+    }
+
+    // If the type conforms to Encodable or Decodable, even via an extension,
+    // the CodingKeys enum is synthesized as a member of the type itself.
+    // Force it into existence.
+    if (nominal) {
+      (void) evaluateOrDefault(
+        Context.evaluator,
+        ResolveImplicitMemberRequest{nominal,
+                   ImplicitMemberAction::ResolveCodingKeys},
+        {});
+    }
+
+    // If the decl has a @main attribute, we need to force synthesis of the
+    // $main function.
+    (void) evaluateOrDefault(
+        Context.evaluator,
+        SynthesizeMainFunctionRequest{const_cast<Decl *>(idc->getDecl())},
+        nullptr);
+
+    for (auto *member : idc->getMembers()) {
+      if (auto *var = dyn_cast<VarDecl>(member)) {
+        // The projected storage wrapper ($foo) might have
+        // dynamically-dispatched accessors, so force them to be synthesized.
+        if (var->hasAttachedPropertyWrapper())
+          (void) var->getPropertyWrapperBackingProperty();
+      }
     }
   }