rollup merge of #24894: bguiz/diagnostic-E0267

rollup merge of #24894: bguiz/diagnostic-E0267

This error indicates that a constant references itself.
All constants need to resolve to a value in an acyclic manner.

For example, neither of the following can be sensibly compiled:

```
const X: u32 = X;
```

```
const X: u32 = Y;
const Y: u32 = X;
```