### What it does
Checks for float literals with a precision greater
than that supported by the underlying type.

### Why is this bad?
Rust will truncate the literal silently.

### Example
```
let v: f32 = 0.123_456_789_9;
println!("{}", v); //  0.123_456_789
```

Use instead:
```
let v: f64 = 0.123_456_789_9;
println!("{}", v); //  0.123_456_789_9
```