This is not a rant, but a well laid-out description of something a widely used software ran into as a result of a change in the compiler they use.

The #ifdef they had in place was a bit hackish, but I wouldn't call it abuse. It is a typical construction for C to do stuff like that which in general isn't without risk, but they have used it without any problems for years. The whole point of the blog post is to start a discussion whether sth. like this should rightfully be flagged as "unexpected behavior" or not.