"helpful" is quite a stretch. The message produced is just as unhelpful and uninformative as the source code line. As was demonstrated, one or both of them gave the recipient not the slightest clue that "//" wouldn't work. So, "use 5.010;" didn't actually help. At most it just induced surprise which was worked around in the obvious manner. Hard to expect otherwise.

All "use 5.010;" does is add a layer to obscure the real problem that people will actually end up dealing with (though, it often just adds a problem layer when there isn't even a problem underneath).

I had proposed ways to drastically improve how helpful it could be. More importantly, those would drastically reduce how often it would be pointlessly obstructive. Unfortunately, the lastest bizarre magic tied to such constructs makes the feature impossible to improve in an any meaningful way.