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`
   |
help: consider specifying the generic argument
   |
LL |     unsafe {swap::<&mut _>(transmute(&a), transmute(&b))};
   |                 ~~~~~~~~~~

error: aborting due to previous error

For more information about this error, try `rustc --explain E0282`.