[Bug libstdc++/48933] New: Infinite recursion in tr1/cmath functions with complex parameters

["bisqwit at iki dot fi" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48933

           Summary: Infinite recursion in tr1/cmath functions with complex
                    parameters
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: bisqwit@iki.fi
                CC: warp@iki.fi


All of the function calls in this example code produce a stack overflow due to
infinite recursion, regardless of optimization level.
Compile with: g++ code.cc
Tested on the following gcc versions: 4.2.4  4.3.5  4.4.6  4.5.2  4.6.1
No compiler warnings or errors are emitted. (Tried even -Wall -W -pedantic
-ansi).

Does not happen on gcc 4.0.4, because tr1/cmath is unavailable.

#include <tr1/cmath>
#include <complex>
int main()
{
    std::tr1::tgamma( std::complex<double> (0.5, 0.0) );
    std::tr1::cbrt( std::complex<double> (0.5, 0.0) );
    std::tr1::asinh( std::complex<double> (0.5, 0.0) );
    std::tr1::acosh( std::complex<double> (1.5, 0.0) );
    std::tr1::atanh( std::complex<double> (0.5, 0.0) );
    std::tr1::erf( std::complex<double> (0.5, 0.0) );
    std::tr1::hypot( std::complex<double> (1.0, 0.0) ,
                     std::complex<double> (1.0, 0.0) );
    std::tr1::logb( std::complex<double> (0.5, 0.0) );
    std::tr1::round( std::complex<double> (0.5, 0.0) );
    std::tr1::trunc( std::complex<double> (0.5, 0.0) );
}

The bug can be traced to all functions in tr1/cmath that look like this:

  template<typename _Tp>
    inline typename __gnu_cxx::__promote<_Tp>::__type
    cbrt(_Tp __x) 
    {
      typedef typename __gnu_cxx::__promote<_Tp>::__type __type;
      return cbrt(__type(__x)); // <-- infinite recursion here
    }