Index: include/lldb/Expression/DiagnosticManager.h
===================================================================
--- include/lldb/Expression/DiagnosticManager.h
+++ include/lldb/Expression/DiagnosticManager.h
@@ -125,6 +125,8 @@
     m_diagnostics.push_back(diagnostic);
   }
 
+  void CopyDiagnostics(DiagnosticManager &otherDiagnostics);
+
   size_t Printf(DiagnosticSeverity severity, const char *format, ...)
       __attribute__((format(printf, 3, 4)));
   size_t PutCString(DiagnosticSeverity severity, const char *cstr);
Index: source/Expression/DiagnosticManager.cpp
===================================================================
--- source/Expression/DiagnosticManager.cpp
+++ source/Expression/DiagnosticManager.cpp
@@ -79,3 +79,12 @@
   AddDiagnostic(cstr, severity, eDiagnosticOriginLLDB);
   return strlen(cstr);
 }
+
+void DiagnosticManager::CopyDiagnostics(DiagnosticManager &otherDiagnostics) {
+  for (const DiagnosticList::value_type &other_diagnostic:
+       otherDiagnostics.Diagnostics()) {
+    AddDiagnostic(
+        other_diagnostic->GetMessage(), other_diagnostic->GetSeverity(),
+        other_diagnostic->getKind(), other_diagnostic->GetCompilerID());
+  }
+}