A user has been going around on this question and trolling -- posting anti-C++ answers -- to a question whose activity ended ~3 months ago, with no technical basis, to every possible comment box. However, when we flag for moderator attention, we flag only a single comment. What's the best way to tell a moderator that while a comment might itself be okay on it's face, but that the comments taken as a whole amount to trolling?
Flag any of the user's comments for moderation attention, and explain the situation. Make sure to point out that there are other comments and provide the user's handle, they can take it from there. Flagging all the user's comments will also make the moderators aware of the behaviour, but describing the situation is obviously quicker.
But if all comments are relevant to their respective posts and follow the normal comment guidelines there might not be much a moderator can do. But do flag anyway, if the behaviour is persistent it will most likely lead to a temporary suspension. If not, at the very least the moderators will clean up the flame-ish comments.
From what you describe, and without checking the question to see the comments myself, it's definitely a troll. Generic "anti-whatever" comments clearly fail the purpose of the comments, as does any comment without a technical basis.
And if you think there's trolling in C++ questions, you really don't want to know what goes on in PHP questions...
Checked every comment in there, flagged about 10 of them... It's not as bad as you describe it (imho), but definitely worth noting. Several poor comments, not just from the one user, and some blame for that should be attributed to the not so very high quality of the question itself.
Flagging the comments is the right way to go.
I kind of took a shotgun approach to this and just purged comments on most answers.
The fact that (nearly) every answer generated extended discussion is a sign that the question itself is a poor fit for Q&A and should perhaps be closed.