The Default
trait was derived on an enum.
Erroneous code example:
#[derive(Default)] enum Food { Sweet, Salty, }
The Default
cannot be derived on an enum for the simple reason that the compiler doesn't know which value to pick by default whereas it can for a struct as long as all its fields implement the Default
trait as well.
If you still want to implement Default
on your enum, you'll have to do it “by hand”:
enum Food { Sweet, Salty, } impl Default for Food { fn default() -> Food { Food::Sweet } }