and yet, peephole.c does specialcase -0 (with a comment and all!-) avoiding constant-folding optimization for it -- making things work fine in Python 2.4.x for high enough x -- it's just that peephole.c's efforts are defeated by a similar optimization applied without specialcase checking in ast.c in Python 2.5.  This is inconsistent: it makes no sense to take SOME of the precautions needed to avoid an issue but not ALL of them, since this makes the issue appear anyway, so those precautions that ARE taken are there for no purpose (except a miniscule slowdown and enlargement of the interpreter:-).  Either we save those few lines of code in peephole.c or add the few lines to ast.c that I suggest in my patch 1678668 -- the current situation makes no sense.