From murdoch.duncan at gmail.com  Wed Jul 15 21:50:16 2015
From: murdoch.duncan at gmail.com (Duncan Murdoch)
Date: Wed, 15 Jul 2015 15:50:16 -0400
Subject: [Rd] Two bugs showing up mostly on SPARC systems
In-Reply-To: <20150714220835.GA28360@cs.toronto.edu>
References: <20150714220835.GA28360@cs.toronto.edu>
Message-ID: <55A6B978.7090004@gmail.com>

On 14/07/2015 6:08 PM, Radford Neal wrote:
> In testing pqR on Solaris SPARC systems, I have found two bugs that
> are also present in recent R Core versions.  You can see the bugs and
> fixes at the following URLs:
> 
>   https://github.com/radfordneal/pqR/commit/739a4960a4d8f3a3b20cfc311518369576689f37
> 
>   https://github.com/radfordneal/pqR/commit/339b7286c7b43dcc6b00e51515772f1d7dce7858
> 
> The first bug, in nls, is most likely to occur on a 64-bit big-endian
> system, but will occur with low probability on most platforms.  
> 
> The second bug, in readBin, may occur on systems in which unaligned
> access to data more than one byte in size is an error, depending on
> details of the compiler.  It showed up with gcc 4.9.2 on a SPARC
> system. The fix slightly changes the error behaviuor, signaling an
> error on inappropriate reads before reading any data, rather than
> after reading one (but not all) items as before.

I've now taken a look at the second bug.  It's a little harder to apply
your patch, since your code is based on an old version of R; current R
has more error checking and allows long vector results from this
function.  But it's basically just a matter of being careful not to make
changes to the newer code.  So this one should go into R-patched more or
less as-is.

Duncan Murdoch



[Rd] Two bugs showing up mostly on SPARC systems
Duncan Murdoch