Troubles encountered with Rust during the making of this library

No way to create dynamic-sized arrays on the stack. A lot of Vulkan functions require passing an array of small elements (small structs or integers). Building such an array with a Vec can be expensive, especially when most of the time the array only contains a single element.
No way to create a *mut T pointer from a *mut c_void() and a size when T is unsized. This had to be implemented in a custom trait.
Can't cast an ImageResource into a Resource even though the former depends on the latter.
This library was designed with specialization in mind. There are several is_compatible trait methods that perform deep comparisons between layouts. With specialization available, these methods could be specialized as true for layouts that are known to always be compatible.
https://github.com/rust-lang/rust/issues/29328