Rust: How do you implement a custom allocator?

1use std::alloc::{GlobalAlloc, Layout};
2
3struct MyAllocator;
4
5unsafe impl GlobalAlloc for MyAllocator {
6    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
7        libc::malloc(layout.size())
8    }
9
10    unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
11        libc::free(ptr)
12    }
13}
14
15#[global_allocator]
16static ALLOCATOR: MyAllocator = MyAllocator;