regression: 3rd party debuggers are incompatible with node8 nighlies

[roblourens]

In #12197, support for --inspect --debug-brk was removed, and --inspect-brk should now be used instead, but --inspect-brk is only supported after 7.6.0.
Since there is no common way to start the inspector across all Node versions that support it, this is an issue for VS Code and other debug clients which now have to determine which version of Node they are launching and select the right arguments, or detect when using one set fails, and try the other set. It's also annoying for anyone who switches node versions often and uses these arguments from the command line.

Would it be possible to retain support for --inspect --debug-brk so that there's one command which can start Node in debug mode across all versions that support the inspector protocol? If it simplifies things, it could be undocumented.

[roblourens]

@joshgav Any thoughts on this? I thought I read at one point that --debug would be an alias for --inspect in the future but I guess that's not the case anymore.

[sam-github]

Keeping uniform behaviour across all current LTS lines is quite helpful. Once all LTS nodes support --inspect-brk, users can switch over to it.

[evanlucas]

yea, I'm +1 on this

[gibfahn]

So the logic is that it's quicker to re-add --debug-brk to Node 7 than to backport --inspect-brk to Node 6 and 4 (and 4 is in maintenance so may never get it)? Makes sense to me.

[sam-github]

We could backport --inspect-brk to node 6, that would allow --debug-brk to be removed from current as soon as 4.x goes out of maintenance, rather than having to wait until 6.x goes out of maintenance.

[sam-github]

@MylesBorins @nodejs/lts what do you think of above? Should we discuss in WG meeting, or should I PR a backport?

[addaleax]

@sam-github If you want to, I think opening a PR is a good idea. There isn’t really any need to wait for a meeting if there is consensus that it should happen.

[ofrobots]

So the logic is that it's quicker to re-add --debug-brk to Node 7 than to backport --inspect-brk to Node 6 and 4 (and 4 is in maintenance so may never get it)? Makes sense to me.

--inspect is only supported since 6.3, so I don't think 4 is relevant here.

From my reading, I think the argument is slightly different than the way you put it. Without knowing the precise version upfront, I think it is hard to know whether --inspect-brk would work. It will never work for users of 6.4.0 for example because a backport would only get into 6.11.0 at the earliest.

@roblourens wouldn't you still need to distinguish Node <6.3.0 from >=6.3.0?

[sam-github]

@ofrobots, good point. I didn't realize the inspector only got introduced halfway into 6.x. So, we'll need to get the backwards-compatible --inspect --debug-brk back, and keep it until 6.x is EOL.

[gibfahn]

@ofrobots, good point. I didn't realize the inspector only got introduced halfway into 6.x. So, we'll need to get the backwards-compatible --inspect --debug-brk back, and keep it until 6.x is EOL.

@sam-github --inspect --debug-brk works fine in v6.x, --debug-brk was removed in master as a semver-major, so the question is whether we re-add it to master and Node 8.

Either way we should backport --inspect-brk to v6.x.