diff --git a/lldb/include/lldb/Target/ThreadPlanStack.h b/lldb/include/lldb/Target/ThreadPlanStack.h
--- a/lldb/include/lldb/Target/ThreadPlanStack.h
+++ b/lldb/include/lldb/Target/ThreadPlanStack.h
@@ -35,8 +35,6 @@
   ThreadPlanStack(const Thread &thread, bool make_empty = false);
   ~ThreadPlanStack() {}
 
-  enum StackKind { ePlans, eCompletedPlans, eDiscardedPlans };
-
   using PlanStack = std::vector<lldb::ThreadPlanSP>;
 
   void DumpThreadPlans(Stream &s, lldb::DescriptionLevel desc_level,
@@ -102,8 +100,6 @@
   void ClearThreadCache();
 
 private:
-  const PlanStack &GetStackOfKind(ThreadPlanStack::StackKind kind) const;
-
   void PrintOneStack(Stream &s, llvm::StringRef stack_name,
                      const PlanStack &stack, lldb::DescriptionLevel desc_level,
                      bool include_internal) const;
diff --git a/lldb/source/Target/ThreadPlanStack.cpp b/lldb/source/Target/ThreadPlanStack.cpp
--- a/lldb/source/Target/ThreadPlanStack.cpp
+++ b/lldb/source/Target/ThreadPlanStack.cpp
@@ -379,19 +379,6 @@
   m_discarded_plans.clear();
 }
 
-const ThreadPlanStack::PlanStack &
-ThreadPlanStack::GetStackOfKind(ThreadPlanStack::StackKind kind) const {
-  switch (kind) {
-  case ePlans:
-    return m_plans;
-  case eCompletedPlans:
-    return m_completed_plans;
-  case eDiscardedPlans:
-    return m_discarded_plans;
-  }
-  llvm_unreachable("Invalid StackKind value");
-}
-
 void ThreadPlanStackMap::Update(ThreadList &current_threads,
                                 bool delete_missing,
                                 bool check_for_new) {