[llvm] [ADT] Implement ArrayRef::operator< and other comparisons (PR #147277)

[Jay Foad via llvm-commits]

jayfoad wrote:

> Does std::span have these operators, and if it does, are they SFINAE-safe there? And if so, should they be made SFINAE-safe here too?

I think you might be mistaking me for a C++ expert :)

As far as I can tell from https://en.cppreference.com/w/cpp/container/span.html, std::span does not have these operators. But note that ArrayRef already had operator==, which std::span does not.

https://github.com/llvm/llvm-project/pull/147277