Well, does VC2015+ not support it? All recent builds of gcc should. How about code::blocks?
It's probably goin to be supported more readily in coming years, so maybe adding some compiler definitions could work, too, but IDK. It depends how important it is.
I read up on this three years back, as it was something that I wanted to be able to do. (In fact, I'd love to add variable-sized arrays to the scripting language, as it's very useful, IMO.)
@Gleeok : I would be willing to help, if I can. I wanted to add some other joystick code to 2.54 anyway. I think our present input support leaves much room for improvement, new back end, or otherwise.