mpz_class possible bug

[Peter MALKIN]

Dear GMP Developers,

I have encountered a problem when compiling a small c++ program using 
gmp version 4.2.1.  My machine is a pentium 4 running Mandriva Linux.  
You will find below more information on the configuration of my 
machine.  I downloaded the source code from the website 
http://www.swox.com/gmp/.  I ran `./configure' (without giving any 
options to configure), `make', and `make check' (all tests passed).  But 
when I compile and run the small program (see attached) the output is 
incorrect.

I compiled the program using g++ without any options.
`g++ -lgmpxx -lgmp gmpbug.cpp'

The output of the program should be as follows:

a = 12 b = 4 c = 3
a - b*c = 0
b = a - b*c
b = 0

However, the output of the program is as follows:

a = 12 b = 4 c = 3
a - b*c = 0
b = a - b*c
b = -24

The bug does not seem to occur in version 4.1.4.  Also, I  get the same 
incorrect output using version 4.2.1 on a sun machine.

Best Regards,

Peter

The following is the output from running `uname -a'.

Linux localhost 2.6.12-12mdksmp #1 SMP Fri Sep 9 17:43:23 CEST 2005 i686 
Intel(R) Pentium(R) 4 CPU 3.00GHz unknown GNU/Linux

The following is the output from running `g++ -v':

Using built-in specs.
Target: i586-mandriva-linux-gnu
Configured with: ../configure --prefix=/usr --libexecdir=/usr/lib 
--with-slibdir=/lib --mandir=/usr/share/man --infodir=/usr/share/info 
--enable-shared --enable-threads=posix --disable-checking 
--enable-languages=c,c++,ada,f95,objc,java 
--host=i586-mandriva-linux-gnu --with-system-zlib --enable-long-long 
--enable-__cxa_atexit --enable-clocale=gnu 
--disable-libunwind-exceptions --enable-java-awt=gtk 
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre 
--enable-gtk-cairo --disable-libjava-multilib
Thread model: posix
gcc version 4.0.1 (4.0.1-5mdk for Mandriva Linux release 2006.0)

The following is the output from running `config.guess':

pentium4-pc-linux-gnu

The following is the output from running `configfsf.guess':

i686-pc-linux-gnu
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