Lancern's Treasure Chest

刚才才发现 std::span 没有 at 成员函数。 查了一下，原因是： I actually proposed at() for std::span as part of P1024r0. It was soundly defeated in LEWG, 0|0|4|4|5. I wasn’t there for the meeting, but from what I understand the feeling was that contracts (which at that time seemed…