https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78420
--- Comment #1 from Tomasz Kamiński <tomaszkam at gmail dot com> --- This is probably effect on changing !lt(a,b) && !lt(b, a) into !(a<b) && !(b<a) and then a == b. Then following comparision is unspecified according to 5.10 [expr.eq] p2.1: If at least one of the operands is a pointer, pointer conversions (4.11), function pointer conversions (4.13), and qualification conversions (4.5) are performed on both operands to bring them to their composite pointer type (Clause 5). Comparing pointers is defined as follows: — (2.1) If one pointer represents the address of a complete object, and another pointer represents the address one past the last element of a different complete object, the result of the comparison is unspecified. However I believe that in light of 20.14.6 [comparisons] p14, above transformation is not allowed.
