You're kidding, right?
(gdb) bt #0 0xaf88f2e0 in std::lround<Fixed<long, 14> > (__x=51.35198974609375) at /usr/include/c++/4.5/tr1_impl/cmath:710 #1 0xaf88f2e8 in std::lround<Fixed<long, 14> > (__x=51.35198974609375) at /usr/include/c++/4.5/tr1_impl/cmath:710 #2 0xaf88f2e8 in std::lround<Fixed<long, 14> > (__x=51.35198974609375) at /usr/include/c++/4.5/tr1_impl/cmath:710 #3 0xaf88f2e8 in std::lround<Fixed<long, 14> > (__x=51.35198974609375) at /usr/include/c++/4.5/tr1_impl/cmath:710 #4 0xaf88f2e8 in std::lround<Fixed<long, 14> > (__x=51.35198974609375) at /usr/include/c++/4.5/tr1_impl/cmath:710 #5 0xaf88f2e8 in std::lround<Fixed<long, 14> > (__x=51.35198974609375) at /usr/include/c++/4.5/tr1_impl/cmath:710
This goes on for a few tens of thousands of stack frames. Time to open /usr/include/c++/4.5/tr1_impl/cmath:710, which has this little gem:
template<typename _Tp>
inline long
lround(_Tp __x)
{
typedef typename __gnu_cxx::__promote<_Tp>::__type __type;
return lround(__type(__x));
}
What happened? Fucked if I know (it's a bit hard to get to the bottom of the problem without being able to get to the bottom of the call stack, for starters; ought to figure out a better way than hitting Enter screen after screen, with gdb asking if I really want to proceed).
Did someone define an std::lround? (A quick grep didn't show signs of that fuckwittery; though I found a couple of std::mins and std::maxes, leading to colorful consequences.)
Did someone define a template lround and did a using namespace std?
Did someone define an implicit casting operator that used to be called here, before this lround template appeared, and became a better match for the argument, whatever that means?
Fucked if I know.
I'm sure this lround business wasn't ever supposed to call itself, though it rather obviously can, depending on what the __gnu_cxx::__promote<_Tp>::__type does.
All that from trying to upgrade from g++ 4.2 to g++ 4.5 (and to gnu++0x – a C++0x flavor brought to you by GNU, enriched by GNU extensions such as strdup.) Oh the joys and safety of static binding – statically changing the meaning of your code with every compiler upgrade!
It's a good thing I rarely get to deal with C++ these days.
(Why upgrade to C++0x, a.k.a. C++11, a.k.a C++0xb? Lambdas, for one thing. Also future job interviews. Embrace C++11, or die trying.)