Detect non-v8 flags

[snoack]

In particular newer versions of Node.js have a bunch of non-v8 flags that are relevant in particular when using v8flags in combination with flagged-respawn or liftoff (like Gulp does), e.g. --experimental-modules.

[phated]

This is an awesome change! Thank you!

I ran node --help and looked through some of their flags and I wonder if we should exclude some others like --exec, --print, --interactive (and their short flags) and any that conflict with gulp flags, like --require and --version. What do you think @snoack ?

[snoack]

--exec, --print, --interactive, --require and --version were implicitly ignored as they are documented like -v, --version which doesn't match our regular expression /\s\s--[\w-]+/gm.

Anyway, I just discovered that there is process.allowedNodeEnvironmentFlags for discovering non-v8 flags (excluding the above except for --require), and started using it here instead.

As for --require, it seems to be a legit flag that can be useful at times. FWIW Gulp's --require option seems redundant with the built-in option as it seems to do exactly the same.

What do you think?

[phated]

I looked into that in the past and I thought there was an issue with it. Let me try to find that previous work.

[phated]

Ah, my previous work was at #51 and I was hoping to remove this module.

I think combining both might do the trick, but I'd like to support older nodes on the first version release of this. Can you restore the node --help support in this PR and then we will land the other changes when we drop node<10 support in the next major?

[snoack]

Are you talking about #51? It seems the issue there was that process.allowedNodeEnvironmentFlags doesn't include v8 flags, hence it cannot replace calling node --v8-options. But here I augment the result of node --v8-options with the contents of process.allowedNodeEnvironmentFlags in order to get both v8 flags and Node.js specific flags.

[phated]

@snoack yep! posted that right before you 😛

What do you think of my "phased" suggestion to getting this to eventually use that API?

[snoack]

You beat me to it. :)

Can you restore the node --help support in this PR [...]?

Done.

What do you think of my "phased" suggestion to getting this to eventually use that API?

Personally, I think it would be fine start using process.allowedNodeEnvironmentFlags if available. The way I implemented it, on Node.js <10.10 you simply would get v8 flags only. But your call.

[snoack]

Thanks for merging! Want to release a new version? Then I can update the dependency in gulpjs/gulp-cli#214 rather than adding a workaround.

[phated]

Yep, I'm just finishing up a couple things and then letting CI run.

[phated]

v3.2.0 published. Thanks for working on this!