Fix duplicate suggestions after an ambiguous command

[teemperor]

Summary

So far lldb is printing this when it finds an ambiguous command:

(lldb) g
Ambiguous command 'g'. Possible matches:
        gdb-remote
        gui
        gdb-remote
        gui

The duplicates come from the fact that we call the same query twice with the same parameters
and add it to the same list. This patch just removes the second query call to GetCommandObject.

As GetCommandObject is const and the name parameter is also not modified, this shouldn't break
anything else. I didn't merge the remaining if statement into the else as I think otherwise the
if obj==nullptr do X else Y pattern in there becomes hard to recognize.

[davide]

LG. thanks for improving the interface, I think all these cleanups are really good.

lldb/trunk/packages/Python/lldbsuite/test/functionalities/wrong_commands/TestWrongCommands.py

def test_ambiguous_command(self):
         self.assertTrue(command_interpreter, VALID_COMMAND_INTERPRETER)
         result = lldb.SBCommandReturnObject()
 
         command_interpreter.HandleCommand("g", result)
         self.assertFalse(result.Succeeded())
         self.assertRegexpMatches(result.GetError(), "Ambiguous command 'g'. Possible matches:")
         self.assertRegexpMatches(result.GetError(), "gui")
         self.assertRegexpMatches(result.GetError(), "gdb-remote")
-        # FIXME: Somehow we get 'gui' and 'gdb-remote' twice in the output.
+        self.assertEquals(1, result.GetError().count("gdb-remote"))
 
     @no_debug_info_test
     def test_unknown_command(self):
         command_interpreter = self.dbg.GetCommandInterpreter()
         self.assertTrue(command_interpreter, VALID_COMMAND_INTERPRETER)
         result = lldb.SBCommandReturnObject()
 
         command_interpreter.HandleCommand("qbert", result)
         self.assertFalse(result.Succeeded())
         self.assertEquals(result.GetError(), "error: 'qbert' is not a valid command.\n")

lldb/trunk/source/Interpreter/CommandInterpreter.cpp

if (cmd_obj == nullptr) {
         cmd_obj =
             BuildAliasResult(full_name, scratch_command, alias_result, result);
         revised_command_line.Printf("%s", alias_result.c_str());
         if (cmd_obj) {
           wants_raw_input = cmd_obj->WantsRawCommandString();
           actual_cmd_name_len = cmd_obj->GetCommandName().size();
         }
       } else {
-        if (!cmd_obj)
-          cmd_obj = GetCommandObject(next_word, &matches);
         if (cmd_obj) {
           llvm::StringRef cmd_name = cmd_obj->GetCommandName();
           actual_cmd_name_len += cmd_name.size();
           revised_command_line.Printf("%s", cmd_name.str().c_str());
           wants_raw_input = cmd_obj->WantsRawCommandString();
         } else {
           revised_command_line.Printf("%s", next_word.c_str());
         }