[Bug c++/31511] New: /usr/include/c++/bits/cmath.tcc: no match for ternary 'operator?:' in '((__n % 2u) != 0u) ? __x : 1'

[bav dot 272304 at gmail dot com]

It is known problem with GNU ISO C++ Library math implementation by Gabriel Dos
Reis.

g++ compiler says something like this:

        /usr/include/c++/bits/cmath.tcc:41: error: no match for
        ternary 'operator?:' in '((__n % 2u) != 0u) ? __x : 1'

It could be fixed by replacing the certain line at the cmath.tcc file

        _Tp __y = __n % 2 ? __x : 1;

with more correct

        _Tp __y = __n % 2 ? __x : _Tp(1);

(see cmath.tcc for details)

To reproduce error, try to pass to std::pow() std::complex<T> object where T
isn't primitive type but some class with arithmetic operators overloaded.

I found it in g++ 3.3.5, g++ 4.0.0, etc.


-- 
           Summary: /usr/include/c++/bits/cmath.tcc: no match for ternary
                    'operator?:' in '((__n % 2u) != 0u) ? __x : 1'
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bav dot 272304 at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31511