error[E0391]: cycle detected when computing layout of `std::option::Option` | = note: ...which requires computing layout of `S`... = note: ...which again requires computing layout of `std::option::Option`, completing the cycle note: cycle used when processing `main` --> $DIR/issue-26548.rs:9:1 | LL | fn main() { | ^^^^^^^^^ error: aborting due to previous error For more information about this error, try `rustc --explain E0391`.