// build-pass #![feature(allocator_api)] #![allow(unused_must_use)] use std::alloc::Allocator; struct BigAllocator([usize; 2]); unsafe impl Allocator for BigAllocator { fn allocate( &self, _: std::alloc::Layout, ) -> Result, std::alloc::AllocError> { todo!() } unsafe fn deallocate(&self, _: std::ptr::NonNull, _: std::alloc::Layout) { todo!() } } fn main() { Box::new_in((), &std::alloc::Global); Box::new_in((), BigAllocator([0; 2])); generic_function(0); } fn generic_function(val: T) { *Box::new_in(val, &std::alloc::Global); }