When 'help' cannot find a command, produce additional help text that also points the user to the apropos and type lookup commands

This is useful in cases such as, e.g.

(lldb) help NSString
(the user meant type lookup)

or

(lldb) help kill
(the user is looking for process kill)

Fixes rdar://24868537

llvm-svn: 262271

1 files changed, 11 insertions, 2 deletions

diff --git a/lldb/source/Commands/CommandObjectCommands.cpp b/lldb/source/Commands/CommandObjectCommands.cpp
index 046698491d8..e2e2bb81ea0 100644
--- a/lldb/source/Commands/CommandObjectCommands.cpp
+++ b/lldb/source/Commands/CommandObjectCommands.cpp
@@ -14,6 +14,7 @@
 
 // Project includes
 #include "CommandObjectCommands.h"
+#include "CommandObjectHelp.h"
 #include "lldb/Core/Debugger.h"
 #include "lldb/Core/IOHandler.h"
 #include "lldb/Core/StringList.h"
@@ -920,8 +921,16 @@ protected:
             }
             else
             {
-                result.AppendErrorWithFormat ("'%s' is not a known command.\nTry 'help' to see a current list of commands.\n",
-                                              command_name);
+                StreamString error_msg_stream;
+                const bool generate_apropos = true;
+                const bool generate_type_lookup = false;
+                CommandObjectHelp::GenerateAdditionalHelpAvenuesMessage(&error_msg_stream,
+                                                                        command_name,
+                                                                        nullptr,
+                                                                        nullptr,
+                                                                        generate_apropos,
+                                                                        generate_type_lookup);
+                result.AppendErrorWithFormat ("%s", error_msg_stream.GetData());
                 result.SetStatus (eReturnStatusFailed);
             }
         }