[Issue 22988] Error: shift by -1 is outside the range `0..31`

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22988

Dennis <dkorpel at live.nl> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |dkorpel at live.nl
         Resolution|---                         |INVALID

--- Comment #1 from Dennis <dkorpel at live.nl> ---
Because AddExpression has precedence over ShiftExpression, it's parsed as:
```
enum b = a ? 1 << (a - 1) : 0;
```
Since a = 0, it results in a shift by -1, which gives an error. To fix, add
parentheses around the shift:
```
enum b = a ? (1 << a) - 1 : 0;
```

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