error[E0391]: cyclic dependency detected
  --> $DIR/issue-23302-2.rs:14:9
   |
LL |     A = Y::B as isize, //~ ERROR E0391
   |         ^^^^^^^^^^^^^ cyclic reference
   |
note: the cycle begins when const-evaluating `Y::A::{{initializer}}`...
  --> $DIR/issue-23302-2.rs:14:9
   |
LL |     A = Y::B as isize, //~ ERROR E0391
   |         ^^^^^^^^^^^^^
note: ...which then requires computing layout of `Y`...
  --> $DIR/issue-23302-2.rs:14:9
   |
LL |     A = Y::B as isize, //~ ERROR E0391
   |         ^^^^
   = note: ...which then again requires const-evaluating `Y::A::{{initializer}}`, completing the cycle.

error: aborting due to previous error

If you want more information on this error, try using "rustc --explain E0391"