So you're saying that turning std::span from a standard library class into a language feature wouldn't break the ABI? How so? How would such a language construct fit into the existing ABI?
(for context: parent is referring to the fact that x64 calling conventions mandate structs larger than 64 bits to be passed in memory, which means that passing a 128bit std::span is going to be less efficient than passing a separate 64bit index and 64bit length, as those can go into registers)
