diff --git a/src/main/cpp/option_processor-internal.h b/src/main/cpp/option_processor-internal.h
index 47f0df4..c552db4 100644
--- a/src/main/cpp/option_processor-internal.h
+++ b/src/main/cpp/option_processor-internal.h
@@ -16,6 +16,7 @@
 #define BAZEL_SRC_MAIN_CPP_OPTION_PROCESSOR_INTERNAL_H_
 
 #include <algorithm>
+#include <set>
 
 #include "src/main/cpp/rc_file.h"
 #include "src/main/cpp/util/exit_code.h"
@@ -30,6 +31,19 @@
 std::vector<std::string> DedupeBlazercPaths(
     const std::vector<std::string>& paths);
 
+// Get the legacy list of rc files that would have been loaded - this is to
+// provide a useful warning if files are being ignored that were loaded in a
+// previous version of Bazel.
+// TODO(b/3616816): Remove this once the warning is no longer useful.
+std::set<std::string> GetOldRcPaths(
+    const WorkspaceLayout* workspace_layout, const std::string& workspace,
+    const std::string& cwd, const std::string& path_to_binary,
+    const std::vector<std::string>& startup_args);
+
+// Returns what the "user bazelrc" would have been in the legacy rc list.
+std::string FindLegacyUserBazelrc(const char* cmd_line_rc_file,
+                                  const std::string& workspace);
+
 std::string FindSystemWideRc();
 
 std::string FindRcAlongsideBinary(const std::string& cwd,