error[E0603]: unit struct `C` is private
  --> $DIR/issue-13407.rs:6:8
   |
LL |     A::C = 1;
   |        ^ private unit struct
   |
note: the unit struct `C` is defined here
  --> $DIR/issue-13407.rs:2:5
   |
LL |     struct C;
   |     ^^^^^^^^^

error[E0070]: invalid left-hand side of assignment
  --> $DIR/issue-13407.rs:6:10
   |
LL |     A::C = 1;
   |     ---- ^
   |     |
   |     cannot assign to this expression

error[E0308]: mismatched types
  --> $DIR/issue-13407.rs:6:12
   |
LL |     A::C = 1;
   |            ^ expected struct `C`, found integer

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0070, E0308, E0603.
For more information about an error, try `rustc --explain E0070`.