error[E0391]: cycle detected when const-evaluating + checking `X::A::{constant#0}`
  --> $DIR/issue-23302-1.rs:4:9
   |
LL |     A = X::A as isize,
   |         ^^^^^^^^^^^^^
   |
   = note: ...which immediately requires const-evaluating + checking `X::A::{constant#0}` again
note: cycle used when simplifying constant for the type system `X::A::{constant#0}`
  --> $DIR/issue-23302-1.rs:4:9
   |
LL |     A = X::A as isize,
   |         ^^^^^^^^^^^^^
   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information

error: aborting due to previous error

For more information about this error, try `rustc --explain E0391`.