SQL: negative numbers surrounded by round brackets are not treated as negative

`SELECT TRUNCATE(-1.5), TRUNCATE(-(1.5)), -(1.5)`

```
TRUNCATE(-1.5) |TRUNCATE(-(1.5))|      1.5      
---------------+----------------+---------------
-1.0           |1.0             |1.5            
```

While the result should be obvious, in case it isn't `-(1.5)` seems to evaluate in the end to 1.5.