Checking if a flag was passed to the compiler

[Nordlöw]

On Thursday, 22 March 2018 at 14:58:56 UTC, Seb wrote:
> For reference and completeness, a simple example:
>
> ```d
> void main()
> {
>     enum isDIP1000 = __traits(compiles, () @safe {
>          int x;
>          int* p;
>          p = &x;
>     });
>     pragma(msg, isDIP1000);
> }
> ```
>
> normal: https://run.dlang.io/is/RID7vh
> -dip1000: https://run.dlang.io/is/1yJfVQ
>
> (this could of course be fancier)

Thanks