#### Note: this error code is no longer emitted by the compiler.
Constants can only be initialized by a constant value or, in a future
version of Rust, a call to a const function. This error indicates the use
of a path (like a::b, or x) denoting something other than one of these
allowed items.
Erroneous code example:
```
const FOO: i32 = { let x = 0; x }; // 'x' isn't a constant nor a function!
```
To avoid it, you have to replace the non-constant value:
```
const FOO: i32 = { const X : i32 = 0; X };
// or even:
const FOO2: i32 = { 0 }; // but brackets are useless here
```