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Aug 23rd, 2019
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  1. macro_rules! assert_type_in {
  2. ($t:ty: $($l:ty),+) => {
  3. {
  4. trait InList {}
  5. $(impl InList for $l {})+
  6.  
  7. fn in_list<T: ?Sized + InList>() {}
  8. let _ = in_list::<$t>;
  9. }
  10. }
  11. }
  12.  
  13. fn main() {
  14. assert_type_in!(u8: u8, u16);
  15. }
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