[lldb] Print the enum values and their description in the argument value help output

[JDevlieghere]

Summary

Print the enum values and their description in the argument value help output.

Here's what the output looks like:

(lldb) help <description-verbosity>
  <description-verbosity> -- How verbose the output of 'po' should be.

     compact : Only show the description string
     full    : Show the full output, including persistent variable's name and type

(lldb) help <log-handler>
  <log-handler> -- The log handle that will be used to write out log messages.

     default  : Use the default (stream) log handler
     stream   : Write log messages to the debugger output stream or to a file if one is specified. A buffer size (in bytes) can be specified with -b. If no buffer size is specified the output is unbuffered.
     circular : Write log messages to a fixed size circular buffer. A buffer size (number of messages) must be specified with -b.
     os       : Write log messages to the operating system log.

Until now, as far as I know, there was no way to get these values and their description.

[jingham]

LGTM

[JDevlieghere]

Rebase on D129703

[clayborg]

nice!

lldb/source/Interpreter/CommandObject.cpp

 #include <map>
 #include <sstream>
 #include <string>
 
 #include <cctype>
 #include <cstdlib>
 
 #include "lldb/Core/Address.h"
+#include "lldb/Interpreter/CommandOptionArgumentTable.h"
 #include "lldb/Interpreter/Options.h"
 #include "lldb/Utility/ArchSpec.h"
 #include "llvm/ADT/ScopeExit.h"
 
 // These are for the Sourcename completers.
 // FIXME: Make a separate file for the completers.
 #include "lldb/Core/FileSpecList.h"
 #include "lldb/DataFormatters/FormatManager.h"
if (entry->help_function) {
     llvm::StringRef help_text = entry->help_function();
     if (!entry->help_function.self_formatting) {
       interpreter.OutputFormattedHelpText(str, name_str.GetString(), "--",
                                           help_text, name_str.GetSize());
     } else {
       interpreter.OutputHelpText(str, name_str.GetString(), "--", help_text,
                                  name_str.GetSize());
     }
-  } else
+  } else {
     interpreter.OutputFormattedHelpText(str, name_str.GetString(), "--",
                                         entry->help_text, name_str.GetSize());
+
+    // Print enum values and their description if any.
+    OptionEnumValues enum_values = g_argument_table[arg_type].enum_values;
+    if (!enum_values.empty()) {
+      str.EOL();
+      size_t longest = 0;
+      for (const OptionEnumValueElement &element : enum_values)
+        longest =
+            std::max(longest, llvm::StringRef(element.string_value).size());
+      str.IndentMore(5);
+      for (const OptionEnumValueElement &element : enum_values) {
+        str.Indent();
+        interpreter.OutputHelpText(str, element.string_value, ":",
+                                   element.usage, longest);
+      }
+      str.IndentLess(5);
+      str.EOL();
+    }
+  }
 }
 
 const char *CommandObject::GetArgumentName(CommandArgumentType arg_type) {
   const ArgumentTableEntry *entry = &(g_argument_table[arg_type]);
 
   // The table is *supposed* to be kept in arg_type order, but someone *could*
   // have messed it up...
 

lldb/test/API/commands/help/TestHelp.py

class HelpCommandTestCase(TestBase):
     def test_help_show_tags(self):
         """ Check that memory find and memory read have the --show-tags option
             but only memory read mentions binary output. """
         self.expect("help memory read", patterns=[
                     "--show-tags\n\s+Include memory tags in output "
                     "\(does not apply to binary output\)."])
         self.expect("help memory find", patterns=[
                     "--show-tags\n\s+Include memory tags in output."])
+
+    @no_debug_info_test
+    def test_help_show_enum_values(self):
+        """ Check the help output for a argument type contains the enum values
+        and their descriptions. """
+        self.expect("help <log-handler>", substrs=[
+            'The log handle that will be used to write out log messages.',
+            'default'  , 'Use the default (stream) log handler',
+            'stream'   , 'Write log messages to the debugger output stream',
+            'circular' , 'Write log messages to a fixed size circular buffer',
+            'os'       , 'Write log messages to the operating system log',
+        ])
+