> It doesn't require an ADT feature and does not require the programmer to specify a type for the possible error value.

I don't think that really matters? Result is "A or error" whereas optional is "A or nil".

Admittedly my wording was sloppy. It's technically a subset of the pattern when taken literally. But there's a very strong convention for the error type in C so at least personally I don't find the restriction off putting.

To me the issue is the name clash. This is most definitely not the "optional" pattern. I actually prefer C++'s "expected" over "result" as far as name clarity goes. "Maybe" would presumably also work.

At the end of the day it's all a non-issue thanks to the syntax. I might not agree with what you expressed but I also realize a name that only shows up in the docs isn't going to pose a problem in practice. Probably more than half the languages out there confuse or otherwise subtly screw up remainder, modulus, and a few closely related mathematical concepts but that doesn't get in the way of doing things.