I find variable-length arrays (i.e. arrays whose length is defined at run-time and typically live on the stack) to be kind of dangerous, and try to avoid them, even in C.

The array at the end of the struct is not a VLA on the stack. When you allocate the struct, you add enough extra to hold the contents of the array. VLAs on the stack are pretty much universally considered a bad idea, as far as I can tell.