Function new_rust_allocator 

pub unsafe fn new_rust_allocator<T>(
    handle: *const T,
    vtable: &'static RustAllocatorVtable<T>,
) -> UniqueRef<Allocator>
where
    T: Send + Sync + 'static,

Creates an allocator managed by Rust code.

Marked unsafe because the caller must ensure that handle is valid and matches what vtable expects.