error[E0391]: cycle detected when processing `<impl at $DIR/issue-23305.rs:15:1: 15:20>`
  --> $DIR/issue-23305.rs:15:12
   |
LL | impl ToNbt<Self> {}
   |            ^^^^
   |
   = note: ...which again requires processing `<impl at $DIR/issue-23305.rs:15:1: 15:20>`, completing the cycle

error: aborting due to previous error

For more information about this error, try `rustc --explain E0391`.