error: missing trait in a trait impl
  --> $DIR/issue-88818.rs:5:5
   |
LL | impl for S { }
   |     ^
   |
help: add a trait here
   |
LL | impl Trait for S { }
   |      +++++
help: for an inherent impl, drop this `for`
   |
LL - impl for S { }
LL + impl S { }
   |

error: aborting due to previous error