error[E0119]: conflicting implementations of trait `From` for type `()`
  --> $DIR/issue-67651.rs:11:1
   |
LL | impl From for () {
   | ---------------- first implementation here
...
LL | impl From for () {
   | ^^^^^^^^^^^^^^^^ conflicting implementation for `()`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0119`.