error[E0425]: cannot find value `HashesEntryLEN` in this scope
  --> $DIR/issue-109141.rs:11:32
   |
LL | struct EntriesBuffer(Box<[[u8; HashesEntryLEN]; 5]>);
   |                                ^^^^^^^^^^^^^^ not found in this scope
   |
help: you might be missing a const parameter
   |
LL | struct EntriesBuffer<const HashesEntryLEN: /* Type */>(Box<[[u8; HashesEntryLEN]; 5]>);
   |                     ++++++++++++++++++++++++++++++++++

error[E0596]: cannot borrow `*self.0` as mutable, as it is behind a `&` reference
  --> $DIR/issue-109141.rs:6:9
   |
LL |         self.0.iter_mut()
   |         ^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable
   |
help: consider changing this to be a mutable reference
   |
LL |     fn a(&mut self) -> impl Iterator {
   |          ~~~~~~~~~

error[E0700]: hidden type for `impl Iterator` captures lifetime that does not appear in bounds
  --> $DIR/issue-109141.rs:6:9
   |
LL |     fn a(&self) -> impl Iterator {
   |          -----     ------------- opaque type defined here
   |          |
   |          hidden type `std::slice::IterMut<'_, [u8; {const error}]>` captures the anonymous lifetime defined here
LL |         self.0.iter_mut()
   |         ^^^^^^^^^^^^^^^^^
   |
help: to declare that `impl Iterator` captures `'_`, you can add an explicit `'_` lifetime bound
   |
LL |     fn a(&self) -> impl Iterator + '_ {
   |                                  ++++

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0425, E0596, E0700.
For more information about an error, try `rustc --explain E0425`.