[lldb] Fix dynamic type resolution for ObjC protocol existentials

An existential whose protocol type is an Objective-C protocol is not
passed in an existential container, but as a plain old instance pointer.
This patch dynamic type resolution failing for those types.

rdar://144028358
(cherry picked from commit 419a0bb)

Author: augusto2112

lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.cpp

@@ -1652,6 +1652,47 @@ swift::Demangle::NodePointer TypeSystemSwiftTypeRef::GetDemangleTreeForPrinting(
   return GetNodeForPrintingImpl(dem, node, flavor, resolve_objc_module);
 }
 
+static bool ProtocolCompositionContainsSingleObjcProtocol(
+  swift::Demangle::NodePointer node) {
+// Kind=ProtocolList
+// Kind=TypeList
+//   Kind=Type
+//     Kind=Protocol
+//       Kind=Module, text="__C"
+//       Kind=Identifier, text="SomeIdentifier"
+if (node->getKind() != Node::Kind::ProtocolList)
+  return false;
+NodePointer type_list = node->getFirstChild();
+if (type_list->getKind() != Node::Kind::TypeList ||
+    type_list->getNumChildren() != 1)
+  return false;
+NodePointer type = type_list->getFirstChild();
+return Contains(type, Node::Kind::Module, swift::MANGLING_MODULE_OBJC);
+}
+
+/// Determine wether this demangle tree contains a node of kind \c kind and with
+/// text \c text (if provided).
+static bool Contains(swift::Demangle::NodePointer node,
+                     swift::Demangle::Node::Kind kind,
+                     llvm::StringRef text = "") {
+  if (!node)
+    return false;
+
+  if (node->getKind() == kind) {
+    if (text.empty())
+      return true;
+    if (!node->hasText())
+      return false;
+    return node->getText() == text;
+  }
+
+  for (swift::Demangle::NodePointer child : *node)
+    if (Contains(child, kind, text))
+      return true;
+
+  return false;
+}
+
 static bool ProtocolCompositionContainsSingleObjcProtocol(
     swift::Demangle::NodePointer node) {
   // Kind=ProtocolList
@@ -1667,10 +1708,7 @@ static bool ProtocolCompositionContainsSingleObjcProtocol(
       type_list->getNumChildren() != 1)
     return false;
   NodePointer type = type_list->getFirstChild();
-  return swift_demangle::FindIf(type, [](NodePointer node) {
-    return node->getKind() == Node::Kind::Module && node->hasText() &&
-           node->getText() == swift::MANGLING_MODULE_OBJC;
-  });
+  return Contains(type, Node::Kind::Module, swift::MANGLING_MODULE_OBJC);
 }
 
 /// Determine wether this demangle tree contains a generic type parameter.