How to enforce compile time evaluation (and test if it was done at compile time)

[Joseph Rushton Wakeling via Digitalmars-d-learn]

On Tuesday, 28 February 2017 at 00:22:28 UTC, sarn wrote:
>> If you ever have doubts, you can always use something like 
>> this to check:
>>
>> assert (__ctfe);
>
> Sorry, "enforce" would more appropriate if you're really 
> checking.

if (!__ctfe) assert(false);

... might be the best option.  That shouldn't be compiled out 
even in -release builds.