It would still break backward compatibility. As a trivial example, {println!("first"); 1u32}.wrapping_add({println!("second"); 1}); currently prints "fir

It would still break backward compatibility. As a trivial example, {println!("first"); 1u32}.wrapping_add({println!("second"); 1}); currently prints "first" before "second", but would switch. But this could theoretically be done at an edition boundary.