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Subject: [hwloc-devel] signed / unsigned
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-12-16 16:29:02

On Dec 16, 2009, at 3:35 PM, Jeff Squyres wrote:

> While preparing to SVN commit, I made the default for HG checkouts to compile with debug and picky modes. I now see a TRUCKLOAD of signed/unsigned comparison warnings. I'll look into these right now...

A bunch of them were fairly straightforward "using int and unsigned together" cases that were easy to fix. But some of them are less clear -- comparing what should be unsigned values with -1. This makes me believe that -1 is being used as a sentinel value in some places -- e.g., in hwloc_obj_t->os_index. It's a "signed" field, but many of the comparisons that are made to it are from "unsigned" variables. And at least in one or two places, it is compared against -1.

Which should be fixed -- make the .os_index field be unsigned (and either have another boolean indicating whether the .os_index value is valid or not, or having a sentinel value for invalid (perhaps ((unsigned) -1)?), or make all the comparison variables be unsigned?

I've attached a patch of what I've done (on my OS X laptop). There's two main sets of changes:

- change easy/obvious int's to unsigned's
- changed .os_index (and 1 or 2 others) to unsigned

But I don't want to commit anything because of the above issue; clearly, I've broken something because comparing .os_index to -1 won't work.

Jeff Squyres