error[E0391]: cycle detected when computing type of `cycle1::{opaque#0}` --> $DIR/auto-trait-leak.rs:12:16 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^ | note: ...which requires borrow-checking `cycle1`... --> $DIR/auto-trait-leak.rs:12:1 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires promoting constants in MIR for `cycle1`... --> $DIR/auto-trait-leak.rs:12:1 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires preparing `cycle1` for borrow checking... --> $DIR/auto-trait-leak.rs:12:1 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires unsafety-checking `cycle1`... --> $DIR/auto-trait-leak.rs:12:1 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires building MIR for `cycle1`... --> $DIR/auto-trait-leak.rs:12:1 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires match-checking `cycle1`... --> $DIR/auto-trait-leak.rs:12:1 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires building THIR for `cycle1`... --> $DIR/auto-trait-leak.rs:12:1 | LL | fn cycle1() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires type-checking `cycle1`... --> $DIR/auto-trait-leak.rs:14:5 | LL | send(cycle2().clone()); | ^^^^ = note: ...which requires evaluating trait selection obligation `cycle2::{opaque#0}: core::marker::Send`... note: ...which requires computing type of `cycle2::{opaque#0}`... --> $DIR/auto-trait-leak.rs:19:16 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^ note: ...which requires borrow-checking `cycle2`... --> $DIR/auto-trait-leak.rs:19:1 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires promoting constants in MIR for `cycle2`... --> $DIR/auto-trait-leak.rs:19:1 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires preparing `cycle2` for borrow checking... --> $DIR/auto-trait-leak.rs:19:1 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires unsafety-checking `cycle2`... --> $DIR/auto-trait-leak.rs:19:1 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires building MIR for `cycle2`... --> $DIR/auto-trait-leak.rs:19:1 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires match-checking `cycle2`... --> $DIR/auto-trait-leak.rs:19:1 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires building THIR for `cycle2`... --> $DIR/auto-trait-leak.rs:19:1 | LL | fn cycle2() -> impl Clone { | ^^^^^^^^^^^^^^^^^^^^^^^^^ note: ...which requires type-checking `cycle2`... --> $DIR/auto-trait-leak.rs:20:5 | LL | send(cycle1().clone()); | ^^^^ = note: ...which requires evaluating trait selection obligation `cycle1::{opaque#0}: core::marker::Send`... = note: ...which again requires computing type of `cycle1::{opaque#0}`, completing the cycle note: cycle used when checking item types in top-level module --> $DIR/auto-trait-leak.rs:1:1 | LL | / use std::cell::Cell; LL | | use std::rc::Rc; LL | | LL | | fn send(_: T) {} ... | LL | | Rc::new(String::from("foo")) LL | | } | |_^ error: aborting due to previous error For more information about this error, try `rustc --explain E0391`.