error[E0506]: cannot assign to `e.0.0.m.x` because it is borrowed
  --> $DIR/box.rs:21:5
   |
LL |     let mut c = || {
   |                 -- borrow of `e.0.0.m.x` occurs here
LL |         e.0.0.m.x = format!("not-x");
   |         --------- borrow occurs due to use in closure
...
LL |     e.0.0.m.x = format!("not-x");
   |     ^^^^^^^^^ assignment to borrowed `e.0.0.m.x` occurs here
LL |
LL |     c();
   |     - borrow later used here

error[E0502]: cannot borrow `e.0.0.m.x` as immutable because it is also borrowed as mutable
  --> $DIR/box.rs:38:20
   |
LL |     let mut c = || {
   |                 -- mutable borrow occurs here
LL |         e.0.0.m.x = format!("not-x");
   |         --------- first borrow occurs due to use of `e.0.0.m.x` in closure
...
LL |     println!("{}", e.0.0.m.x);
   |                    ^^^^^^^^^ immutable borrow occurs here
LL |
LL |     c();
   |     - mutable borrow later used here
   |
   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0506]: cannot assign to `e.0.0.m.x` because it is borrowed
  --> $DIR/box.rs:55:5
   |
LL |     let c = || {
   |             -- borrow of `e.0.0.m.x` occurs here
LL |         println!("{}", e.0.0.m.x);
   |                        --------- borrow occurs due to use in closure
...
LL |     e.0.0.m.x = format!("not-x");
   |     ^^^^^^^^^ assignment to borrowed `e.0.0.m.x` occurs here
LL |
LL |     c();
   |     - borrow later used here

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0502, E0506.
For more information about an error, try `rustc --explain E0502`.