error: item does not constrain `FooRet::{opaque#0}`
  --> $DIR/issue-70877.rs:25:8
   |
LL | pub fn ham() -> Foo {
   |        ^^^
   |
   = note: consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`
note: this opaque type is supposed to be constrained
  --> $DIR/issue-70877.rs:18:19
   |
LL | pub type FooRet = impl std::fmt::Debug;
   |                   ^^^^^^^^^^^^^^^^^^^^

error: item does not constrain `FooRet::{opaque#0}`
  --> $DIR/issue-70877.rs:30:8
   |
LL | pub fn oof() -> impl std::fmt::Debug {
   |        ^^^
   |
   = note: consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`
note: this opaque type is supposed to be constrained
  --> $DIR/issue-70877.rs:18:19
   |
LL | pub type FooRet = impl std::fmt::Debug;
   |                   ^^^^^^^^^^^^^^^^^^^^

error: item does not constrain `Foo::{opaque#0}`
  --> $DIR/issue-70877.rs:30:8
   |
LL | pub fn oof() -> impl std::fmt::Debug {
   |        ^^^
   |
   = note: consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`
note: this opaque type is supposed to be constrained
  --> $DIR/issue-70877.rs:23:16
   |
LL | pub type Foo = impl Iterator<Item = FooItem>;
   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: opaque type's hidden type cannot be another opaque type from the same scope
  --> $DIR/issue-70877.rs:35:12
   |
LL |     return func(&"oof");
   |            ^^^^^^^^^^^^ one of the two opaque types used here has to be outside its defining scope
   |
note: opaque type whose hidden type is being assigned
  --> $DIR/issue-70877.rs:30:17
   |
LL | pub fn oof() -> impl std::fmt::Debug {
   |                 ^^^^^^^^^^^^^^^^^^^^
note: opaque type being used as hidden type
  --> $DIR/issue-70877.rs:18:19
   |
LL | pub type FooRet = impl std::fmt::Debug;
   |                   ^^^^^^^^^^^^^^^^^^^^

error: aborting due to 4 previous errors