[Bug c++/46133] New: constexpr needed for C99 complex type creation from ctor with two floating point types

[bkoz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46133

           Summary: constexpr needed for C99 complex type creation from
                    ctor with two floating point types
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c++
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: b...@gcc.gnu.org


Small reproducer:

struct complex
{
  typedef float value_type;
  typedef __complex__ float _ComplexT;

  constexpr complex(_ComplexT __z) : _M_value(__z) { }

  constexpr complex(float __r = 0.0f, float __i = 0.0f)
  : _M_value(__r + __i * 1.0fi) { }

private:
  _ComplexT _M_value;
};

constexpr complex c1;

Gives:

%$bin/H-x86_64-gcc-constexpr.20101022/bin/g++ -c -std=gnu++0x complex_wanna.cc
complex_wanna.cc:16:19: error: ‘(__complex__ float){0.0f, 0.0f}’ is not a
constant expression
complex_wanna.cc:16:19: error: in expansion of ‘complex(0.0f, 0.0f)’