id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8315	tee function template does not work for std streams	Claudio Bley	Jonathan Turkanis	"= General Info =

OS:: Windows 7 64bit

Compiler:: MSVC 10

= The Code =
{{{
#!cpp
std::ostringstream out;
boost::iostreams::tee(out);
}}}

= Compiler Output / Error =

{{{
Boost\Boost_1_53\boost/iostreams/tee.hpp(208): error C2440: '<function-style-cast>' : cannot convert from 'const std::ostringstream' to 'boost::iostreams::tee_filter<Device>'
 with
 [
     Device=std::ostringstream
 ]
 No constructor could take the source type, or constructor overload resolution was ambiguous
 recurse.cpp(14) : see reference to function template instantiation 'boost::iostreams::tee_filter<Device> boost::iostreams::tee<std::ostringstream>(const Sink &)' being compiled
 with
 [
     Device=std::ostringstream,
     Sink=std::ostringstream
 ]
}}}

= Analysis =

The parameter is given to the tee function template as a const-reference:
{{{
#!cpp
template<typename Sink>
tee_filter<Sink> tee(const Sink& snk) 
{ return tee_filter<Sink>(snk); }
}}}
Quoting the documentation:

  The function parameter is a non-const reference if Sink is a stream 
  or stream buffer type, and a const reference otherwise.

Actually, this really does not apply to the function parameter, but rather to the tee_filter ctor parameter.

So, this boils down to passing a const-reference type to a non-const-reference type as an argument.

= Proposed Solution =

Remove the ""const"" qualifier from the tee function parameter(s)."	Bugs	closed	To Be Determined	iostreams	Boost 1.53.0	Problem	fixed	tee iostreams