@hyphen @fluffy @tuxcrafting When you ask "Is this part of the language?", the answer for the actual multi return would be yes. But for tuples, it would be no, because tuples are high lever data structure and are implemented using the language but are not part of the language.
But then again the question is "does it matter?" and I think you're right, it doesn't. I found this[1] very interesting article. In C++, the compiler treats the tuple values in a special way, they more or less work the same way as the multi value returns. Each tuple value gets pushed to the stack/register independently instead of just the address of the tuple descriptor (if there is any, I don't know C++ that well). I'm not sure how other languages implement them, but yeah, in C++ they're essentially same as multi value return.

[1] https://dr-knz.net/measuring-multiple-return-values-in-go-and-cpp.html

@r technically that optimization is not specific to tuples, it would treat any type that way. From language feature point of view you can call a function with a tuple as the parameters with std::apply, and if the function returns a tuple you can decompose it in place
auto [x, y] = func();
In general any type can work this way if you make it tuple-like by specializing a couple of standard templates for it. That said the tuple itself is way more powerful and important than any of that syntax sugar.

this post was made by c++ gang (now that has got to be a real gang)
@hyphen @tuxcrafting @fluffy