Unstable build/host qsorts causing differing generated target code

[Joseph Myers]

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).

-- 
Joseph S. Myers
joseph@codesourcery.com