Builds using libc++ hardening was hitting asserts like
libc++ Hardening assertion
!__comp(*(__first + __a), *(__first + __b)) failed:
Your comparator is not a valid strict-weak ordering
printf-debugging revealed that symbols like "?ST@@3JA" were not
comparing equal with themselves. It turns out the comparison was done
with
return S1.compare_insensitive(S2.data());
and even when &S1 == &S2, S1 and S2.data() may not refer to identical
strings, since data() may not have a null terminator where the StringRef
locally ends.
This fixes the ordering, simplifies the code, and makes it a little
faster :)
Fixes: #163755
2265d3240f