__has_side_effects

[Uknown]

On Sunday, 1 April 2018 at 10:23:40 UTC, Andrei Alexandrescu 
wrote:
> On 4/1/18 2:22 AM, Uknown wrote:
>> [...]
>
> That's a great initiative, and a worthy trait for the stdlib. I 
> think you'd have an easier time if you reasoned from the other 
> end. A function is strongly pure if all of the following are 
> true:
>
> [...]

I got a working implementation that satisfies your requirements 
in about 60 lines.
I will make a Pull Request as soon as I write the Docs and 
unittests.

Here's the implementation: https://run.dlang.io/is/kVpv36