Hi, On Fri, 12 Jan 2018, Joseph Myers wrote:
> On Fri, 12 Jan 2018, Alexander Monakov wrote: > > > No. The qsort_chk effort was limited to catching instances where comparators > > are invalid, i.e. lack anti-commutativity (may indicate A < B < A) or > > transitivity property (may indicate A < B < C < A). Fixing them doesn't > > imply making corresponding qsort invocations stable. > > Incidentally, does it detect being invalid because of comparing A != A? > (I don't know if qsort implementations ever do compare an element to > itself, but I did once notice in a patch review that a comparator could > have compared an element unequal to itself). Many years ago I ran into a qsort implementation (some Sun one? too long ago) where indeed qsort was calling cmp(a,a). I ran into this case only because one of the cmp() implementations didn't return 0 then, and qsort was Very Surprised by that :) Ciao, Michael.
