What does this mean?

[nbecker@fred.net]

>>>>> "Mike" == Mike Stump <mrs@windriver.com> writes:

    >> To: gcc@gcc.gnu.org
    >> From: nbecker@fred.net
    >> Date: 06 Apr 2001 13:12:35 -0400

    >> In the following diagnostic, why does "(+rng)" mean?

    >> TestSigGen.cc:30:   instantiated from here
    >> SigGen.H:41: could not convert 
    >> `uniform_real<boost::random::mersenne_twister<long unsigned int, 624, 
    >> 397, 31, -1727483681, 11, 7, -1658038656, 15, -272236544, 18, 
    -948541730> ,double>((+rng), 0x000000000000000000000000, 
    >> 0x000000c06821a2da0fc90140)' to `boost::uniform_real<rng_t, double> &'
    >> SigGen.H:18: in passing argument 3 of `maybe_random<Rng>::maybe_random 
    >> (bool, typename Rng::result_type, Rng &) [with Rng = 
    >> boost::uniform_real<rng_t, double>]'

    Mike> Just a wild ass guess, but is it the name of a user declared variable
    Mike> in the source code fed to the compiler?  I noticed that you didn't ask
    Mike> what 0x000000c06821a2da0fc90140 meant.

I don't understand why it says "(+rng)".  Why the plus sign?  Why the
paranthesis?  I don't think my question is stupid.