[lldb] Fix stale Symbol pointer crash in statusline after 'target symbols add'

lldb/include/lldb/Core/Debugger.h

@@ -457,6 +457,9 @@ class Debugger : public std::enable_shared_from_this<Debugger>,
   /// Redraw the statusline if enabled.
   void RedrawStatusline(std::optional<ExecutionContextRef> exe_ctx_ref);
 
+  /// Flush cached state (e.g. stale execution context in the statusline).
+  void FlushStatusLine();
+
   /// This is the correct way to query the state of Interruption.
   /// If you are on the RunCommandInterpreter thread, it will check the
   /// command interpreter state, and if it is on another thread it will

lldb/include/lldb/Core/Statusline.h

@@ -32,6 +32,9 @@ class Statusline {
   /// Redraw the statusline.
   void Redraw(std::optional<ExecutionContextRef> exe_ctx_ref);
 
+  /// Clear the cached execution context to discard stale pointers.
+  void ClearExecutionContext();
+
   /// Inform the statusline that the terminal dimensions have changed.
   void TerminalSizeChanged();
 

lldb/source/Core/Debugger.cpp

@@ -1284,6 +1284,15 @@ void Debugger::RedrawStatusline(
   m_statusline->Redraw(exe_ctx_ref);
 }
 
+void Debugger::FlushStatusLine() {
+  std::lock_guard<std::mutex> guard(m_statusline_mutex);
+
+  if (!m_statusline)
+    return;
+
+  m_statusline->ClearExecutionContext();
+}
+
 ExecutionContext Debugger::GetSelectedExecutionContext() {
   bool adopt_selected = true;
   ExecutionContextRef exe_ctx_ref(GetSelectedTarget().get(), adopt_selected);

lldb/source/Core/Statusline.cpp

@@ -125,6 +125,8 @@ void Statusline::UpdateScrollWindow(ScrollWindowMode mode) {
   m_debugger.RefreshIOHandler();
 }
 
+void Statusline::ClearExecutionContext() { m_exe_ctx_ref.ClearFrame(); }
+
 void Statusline::Redraw(std::optional<ExecutionContextRef> exe_ctx_ref) {
   // Update the cached execution context.
   if (exe_ctx_ref)

lldb/source/Target/Process.cpp

@@ -6025,6 +6025,7 @@ void Process::Flush() {
   m_extended_thread_stop_id = 0;
   m_queue_list.Clear();
   m_queue_list_stop_id = 0;
+  GetTarget().GetDebugger().FlushStatusLine();
 }
 
 lldb::addr_t Process::GetCodeAddressMask() {