A mysterious compilation error: cannot convert from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T>'
- by Stephane Rolland
I wanted to protect the access to a log file that I use for multithreaded logging with boostlog library.
I tried this stream class
class ThreadSafeStream
{
public:
template <typename TInput>
const ThreadSafeStream& operator<< (const TInput &tInput) const
{
// some thread safe file access
return *this;
}
};
using it this way (text_sink is a boostlog object):
//...
m_spSink.reset(new text_sink);
text_sink::locked_backend_ptr pBackend = m_spSink->locked_backend();
const boost::shared_ptr< ThreadSafeStream >& spFileStream = boost::make_shared<ThreadSafeStream>();
pBackend->add_stream(spFileStream); // this causes the compilation error
and I get this mysterious error: cannot convert from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T>'
the whole compile error:
Log.cpp(79): error C2664: 'boost::log2_mt_nt5::sinks::basic_text_ostream_backend<CharT>::add_stream' : cannot convert parameter 1 from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T> &'
1> with
1> [
1> CharT=char
1> ]
1> and
1> [
1> T=ThreadSafeStream
1> ]
1> and
1> [
1> T=std::basic_ostream<char,std::char_traits<char>>
1> ]
1> Reason: cannot convert from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T>'
1> with
1> [
1> T=ThreadSafeStream
1> ]
1> and
1> [
1> T=std::basic_ostream<char,std::char_traits<char>>
1> ]
1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
I suspect that I am not well defining the operator<<()... but I don't find what is wrong.
