error[E0391]: cycle detected when type-checking `foo`
  --> $DIR/clone-rpit.rs:13:1
   |
LL | pub fn foo<'a, 'b>() -> impl Clone {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: ...which requires coroutine witness types for `foo::{closure#0}`...
  --> $DIR/clone-rpit.rs:14:5
   |
LL |     move |_: ()| {
   |     ^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `foo::{closure#0}`...
  --> $DIR/clone-rpit.rs:14:5
   |
LL |     move |_: ()| {
   |     ^^^^^^^^^^^^
note: ...which requires preparing `foo::{closure#0}` for borrow checking...
  --> $DIR/clone-rpit.rs:14:5
   |
LL |     move |_: ()| {
   |     ^^^^^^^^^^^^
note: ...which requires checking if `foo::{closure#0}` contains FFI-unwind calls...
  --> $DIR/clone-rpit.rs:14:5
   |
LL |     move |_: ()| {
   |     ^^^^^^^^^^^^
note: ...which requires building MIR for `foo::{closure#0}`...
  --> $DIR/clone-rpit.rs:14:5
   |
LL |     move |_: ()| {
   |     ^^^^^^^^^^^^
note: ...which requires match-checking `foo::{closure#0}`...
  --> $DIR/clone-rpit.rs:14:5
   |
LL |     move |_: ()| {
   |     ^^^^^^^^^^^^
note: ...which requires type-checking `foo::{closure#0}`...
  --> $DIR/clone-rpit.rs:14:5
   |
LL |     move |_: ()| {
   |     ^^^^^^^^^^^^
   = note: ...which again requires type-checking `foo`, completing the cycle
note: cycle used when computing type of opaque `foo::{opaque#0}`
  --> $DIR/clone-rpit.rs:13:25
   |
LL | pub fn foo<'a, 'b>() -> impl Clone {
   |                         ^^^^^^^^^^
   = 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

error: aborting due to 1 previous error

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