The first stack / heap collisions were not using VLA but fixed size arrays on the stack. Nowadays compilers do stack probing, which solves this problem also for VLAs. Yes, you get a segfault for stack overflow, but this has not much to do with VLAs or not, but with putting too much stuff on the stack. The thing is, VLAs allow you to reduce stack usage, by putting the right amount of stack on the stack and not a worst case. The only downside is that they make it harder to control stack usage, but not a lot harder. So no, I do not think avoiding VLAs is good engineering.