error[E0391]: cycle detected when computing layout of `Wrapper<()>` | = note: ...which requires computing layout of `<() as Trait>::Assoc`... = note: ...which again requires computing layout of `Wrapper<()>`, completing the cycle = note: cycle used when computing layout of `core::option::Option>` = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information note: the above error was encountered while instantiating `fn abi::<()>` --> $DIR/post-mono-layout-cycle.rs:19:5 | LL | abi::(None); | ^^^^^^^^^^^^^^ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0391`.