error[E0308]: mismatched types
  --> $DIR/param-mismatch-trait-fn.rs:6:23
   |
LL |     T::same_type([x], Some(y));
   |     ------------ ---  ^^^^^^^ expected `[X; 1]`, found `Option<Y>`
   |     |            |
   |     |            expected all arguments to be this `[X; 1]` type because they need to match the type of this parameter
   |     arguments to this function are incorrect
   |
   = note: expected array `[X; 1]`
               found enum `Option<Y>`
note: associated function defined here
  --> $DIR/param-mismatch-trait-fn.rs:2:8
   |
LL |     fn same_type<T>(_: T, _: T);
   |        ^^^^^^^^^ -  -     - this parameter needs to match the `[X; 1]` type of parameter #1
   |                  |  |
   |                  |  parameter #2 needs to match the `[X; 1]` type of this parameter
   |                  parameter #1 and parameter #2 both reference this parameter `T`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.