Needs to remove run-time check which is always `false`

[SergeyKopienko]

https://github.com/uxlfoundation/oneDPL/blob/33828957adb7af014900969e2c25aa0813b48ea8/include/oneapi/dpl/experimental/kt/single_pass_scan.h#L389

Probably better replace to

#if 0
    // code
#else
    // code
#endif

[akukanov]

Tagging @danhoeflinger

I think #if 0 is not really better that the "runtime" check; it's still dead code. In some sense it's even worse, because now this code should at least compile without errors.

In principle, any "branching" is only needed if we expect the two code variants to coexist for some time in the future. In that case there should be a better condition check instead of "true/false", at least a named variable/macro.

If we do not expect the need to have two variants of the code and want to avoid dead code, I would just use comments.

[danhoeflinger]

Perhaps @adamfidel is the better person to tag here. I'm happy to make some changes here to improve this, but I didn't write this code.

[adamfidel]

I agree that commenting out the if (0) branch would be an acceptable alternative to what is there currently.