error[E0072]: recursive types `A` and `B` have infinite size --> $DIR/issue-105231.rs:1:1 | LL | struct A(B); | ^^^^^^^^^^^ ---- recursive without indirection LL | LL | struct B(A>); | ^^^^^^^^^^^ ------- recursive without indirection | help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle | LL ~ struct A(Box>); LL | LL ~ struct B(Box>>); | error[E0275]: overflow evaluating the requirement `A>>>>>>: Send` --> $DIR/issue-105231.rs:5:28 | LL | impl Foo for T where T: Send {} | ^^^^ | = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_105231`) note: required because it appears within the type `B>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>` --> $DIR/issue-105231.rs:3:8 | LL | struct B(A>); | ^ error: aborting due to 2 previous errors Some errors have detailed explanations: E0072, E0275. For more information about an error, try `rustc --explain E0072`.