5 trait ZeroSized: Sized {
6 const I_AM_ZERO_SIZED: ();
7 fn requires_zero_size(self);
10 impl<T: Sized> ZeroSized for T {
11 const I_AM_ZERO_SIZED: () = [()][std::mem::size_of::<Self>()]; //~ WARN any use of this value
12 //~| WARN this was previously accepted by the compiler but is being phased out
13 fn requires_zero_size(self) {
14 let () = Self::I_AM_ZERO_SIZED; //~ ERROR erroneous constant encountered
15 println!("requires_zero_size called");
20 ().requires_zero_size();
21 42_u32.requires_zero_size();