#![allow(unused_variables)] #![feature(allocator_api)] fn main() { fn _inner() -> core::result::Result<(), impl core::fmt::Debug> { let mut five = Box::::try_new_uninit()?; five.write(5); let five = unsafe { five.assume_init() }; assert_eq!(* five, 5); Ok::<(), std::alloc::AllocError>(()) } _inner().unwrap() }