error[E0282]: type annotations needed --> $DIR/issue-24013.rs:5:13 | LL | unsafe {swap::<&mut _>(transmute(&a), transmute(&b))}; | ^^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `swap` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0282`.