[Issue 24412] No predefined version for 64bit ?!

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24412

--- Comment #10 from Iain Buclaw <ibuclaw at gdcproject.org> ---
(In reply to Manu from comment #2)
> That would tell you if you have 64bit address space. Not the same thing.
```
import gcc.builtins : ___builtin_machine_int;
static if (__builtin_machine_int.sizeof == 8):
```

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