generic-unused-impl.coverage

   LL|       |// Regression test for #135235.
   LL|       |trait Foo {
   LL|       |    type Assoc;
   LL|       |
   LL|       |    fn from(s: Self::Assoc) -> Self;
   LL|       |}
   LL|       |
   LL|       |struct W<T>(T);
   LL|       |
   LL|       |impl<T: Foo> From<[T::Assoc; 1]> for W<T> {
   LL|      0|    fn from(from: [T::Assoc; 1]) -> Self {
   LL|      0|        let [item] = from;
   LL|      0|        W(Foo::from(item))
   LL|      0|    }
   LL|       |}
   LL|       |
   LL|      1|fn main() {}