Function with_alloca 

pub fn with_alloca<R>(
    size: usize,
    f: impl FnOnce(&mut [MaybeUninit<u8>]) -> R,
) -> R

Allocates [u8; size] memory on stack and invokes closure with this slice as argument.

Safety

This function is safe because c_with_alloca (which is internally used) will always returns non-null pointer.

Potential segfaults or UB

When using this function in wrong way your program might get UB or segfault “for free”:

• Using memory allocated by with_alloca outside of it e.g closure is already returned but you somehow managed to store pointer to memory and use it.

• Allocating more memory than thread stack size.

  This will trigger segfault on stack overflow.