https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91227
--- Comment #8 from Martin Sebor <msebor at gcc dot gnu.org> --- (In reply to rguent...@suse.de from comment #5) > Does "unspecified" allow p > q != !(p <= q)? I think so (it's not > implementation defined). The exact C++ words that apply here are: (4.3) Otherwise [if two unequal pointers don't point into the same object], neither pointer is required to compare greater than the other. (it's not explicitly unspecified, but it sounds at least as loose). So the answer is yes. I agree with producing a sensible result for QoI (especially if there's no warning). A result that's consistent between [in]equality and relational expressions would qualify. I also agree that diagnosing all these unspecified (or undefined in C) cases would be helpful as they (at least in the straightforward instances) are most likely coding mistakes. I might look into it, though my first concern is about the instances that result from some earlier transformations and where warnings will be seen as false positives.
