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.
Compilers can often do some static bounds-checking of such arrays. But because those features had been introduced together with variable-length array stack variables , people have lumped them all together and thus shunned these features that could otherwise have added safety.
BTW, one thing you should never do is use variable-length array declarations and alloca() in the same function. As VLA variables have scope life-time and allocas have function life-time they are not compatible — and allocations could overlap. Yet, not all compilers (/versions) that support both warn when they are used together.