error[E0391]: cycle detected when simplifying constant for the type system `test::{constant#0}`
  --> src/lib.rs:7:22
   |
7  |   fn test() where [u8; {
   |  ______________________^
8  | |     let _: Foo<[u8; 3 + 4]>;
9  | |     3
10 | | }]: Sized {
   | |_^
   |
note: ...which requires const-evaluating + checking `test::{constant#0}`...
  --> src/lib.rs:7:22
   |
7  |   fn test() where [u8; {
   |  ______________________^
8  | |     let _: Foo<[u8; 3 + 4]>;
9  | |     3
10 | | }]: Sized {
   | |_^
note: ...which requires type-checking `test::{constant#0}`...
  --> src/lib.rs:7:22
   |
7  |   fn test() where [u8; {
   |  ______________________^
8  | |     let _: Foo<[u8; 3 + 4]>;
9  | |     3
10 | | }]: Sized {
   | |_^
   = note: ...which requires evaluating trait selection obligation `[u8; _]: std::marker::Sized`...
   = note: ...which again requires simplifying constant for the type system `test::{constant#0}`, completing the cycle
note: cycle used when checking that `test` is well-formed
  --> src/lib.rs:10:5
   |
10 | }]: Sized {
   |     ^^^^^