Unable to use V8's --debug options due to Node option parsing

[metamatt]

V8 has several debug options which would be enabled by passing various flags starting with --debug on the nodejs command line:

magi@ubuntu ~/s/d/experiments> node --v8-options | grep -- --debug
  --debug_code (generate extra code (assertions) for debugging)
  --debugger_auto_break (automatically set the debug break flag when debugger commands are in the queue)
  --debugger (Enable JavaScript debugger)
  --debugger_agent (Enable debugger agent)
  --debugger_port (Port to use for remote debugging)
  --debug_compile_events (Enable debugger compile events)
  --debug_script_collected_events (Enable debugger script collected events)

However, trying to use any of these results in

magi@ubuntu ~/s/d/experiments> node --debugger_auto_break
Bad debug option.
Usage: node [options] [ -e script | script.js ] [arguments]
       node debug script.js [arguments]
...

This is because any command-line option starting with the string --debug gets passed to ParseDebugOpt and ParseDebugOpt always exits the process if it doesn't find one of Node's own debug options.

I think this needs a passthrough to allow use of the V8 options.

[metamatt]

Alternately, ParseDebugOpt handles only --debug, --debug=, --debug-brk, and --debug-brk=. We could pass only those to it, and let the others fall through to V8. Is the stricter Bad debug option behavior useful to anyone?

[bnoordhuis]

Fixed in bd9c666, thanks for the report.