I think you're talking about perfect forwarding and reference collapsing rules [1, 2], introduced in C++11, but that is a bit different thing occurring only in

I think you're talking about perfect forwarding and reference collapsing rules [1, 2], introduced in C++11, but that is a bit different thing occurring only in a template instantiation context. Normally, you wouldn't see triple ampersands in sane C++ code, afaik. [1] http://thbecker.net/articles/rvalue_references/section_08.html http://thbecker.net/articles/rvalue_references/section_08.ht... [2] https://en.cppreference.com/w/cpp/language/reference https://en.cppreference.com/w/cpp/language/reference