‘mutex’ in namespace ‘boost’ does not name a type

Question

I get this error when I try to compile the following code:

#include <boost/signals2/mutex.hpp>

class Log
{
    private:
        boost::mutex m_log;
...
}

The error I get when I try to compile is:

error: ‘mutex’ in namespace ‘boost’ does not name a type

Answer 1

it is in the sub namespace

boost::signals2::mutex