Using a rust allocator in C

I have an ffi crate for a C library that can take: typedef struct { void* pUserData; void* (* onMalloc)(size_t sz, void* pUserData); void* (* onRealloc)(void* p, size_t sz, void* pUserData); void (* onFree)(void* p, void* pUserData); } ma_allocation_callbacks; There may be some value in using the same allocator in Rust and C and I wanted to implement this. I had found this, which gave me a good starting point - cassender For now, I am mostly interested in the unstable feature...