[gerbenst]

https://godbolt.org/z/zPWr73qjc

Here is an implementation. This should work with all types. Unfortunate I had to annotate with restrict, but a small price to pay.

[CJefferson]

I think life gets harder when you have to deal with iterators, and have to use iterator::reference (which might not be a raw C++ reference, although it almost always is in practice).