#include 
#include 

int main(int argc, char **argv)
{
    // 1) According to the standard, this must pass:
    assert(argv[argc] == nullptr);


    std::span spn { argv, argv + argc };

    // 2) Undefined behavior
    assert(spn[argc] == nullptr);

    // 3) Is this allowed ?
    assert(spn.data()[argc] == nullptr);
}

The question is about the third assert

Since I do not index the span itself, but rather take the address and basically treat it as an array, I believe this is correct (and it passes).
According to Chatgpt, this is UB.

So the question is:
Is the 3rd assert statement well-defined behavior and will it pass ?