error[E0391]: cycle detected when const checking `FOO`
  --> $DIR/issue-17252.rs:1:20
   |
LL | const FOO: usize = FOO;
   |                    ^^^
   |
   = note: ...which again requires const checking `FOO`, completing the cycle
note: cycle used when const checking `main::{{constant}}#0`
  --> $DIR/issue-17252.rs:4:18
   |
LL |     let _x: [u8; FOO]; // caused stack overflow prior to fix
   |                  ^^^

error: aborting due to previous error

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