Re: [sigc] Build failed

[Chris Vine <chris cvine freeserve co uk>]

On Thu, 07 Mar 2013 10:35:42 +0100
Kjell Ahlstedt <kjell ahlstedt bredband net> wrote:
> If libsigc++ can't be built on Mac OS X I'd like to know why, and
> what can be done about it.
> The error messages says that no definition is available for
> std::basic_ostream<>& std::operator<<(std::basic_ostream<>&, const 
> std::basic_string<>&).
> I thought #include <iostream> should fix that. Is any other include
> file necessary in OS X?
> You can try with removing the SIGC_USING_STD macros. They are 
> unnecessary since many years. But I'd be surprised if it fixes your
> problem.

Including <ostream>, which is where std::ostream/std::basic_ostream are
defined, may do it.  C++98 only requires <iostream> to declare the
standard stream objects (not classes) (§27.3), which I guess it could
do by only including <iosfwd>.  <ostream> is also where operator::<<()
for stream objects is declared.  <istream> defines the
std::istream/std::iostream/std::basic_istream/std::basic_iostream
classes and templates and declares operator::>>().

C++11 seems to require <iostream> to include <ostream> (§27.4.1), so
the -std=c++0x compiler flag may also have the desired effect.

Chris