boost & g++: no matching function for call to 'current_path()'

Question

I have the following code:

boost::filesystem::path p = boost::filesystem::current_path();

But I get this error from g++:

filesystem.cc: In function ‘int main(int, char**)’:
filesystem.cc:11: error: no matching function for call to ‘current_path()’
/usr/include/boost/filesystem/operations.hpp:769: note: candidates are: void boost::filesystem::current_path(const boost::filesystem::path&)
/usr/include/boost/filesystem/operations.hpp:771: note:                 void boost::filesystem::current_path(const boost::filesystem::wpath&)

In /usr/include/boost/filesystem/operations.hpp, I have the following:

template< class Path >
Path current_path()
{
  typename Path::external_string_type ph;
  system::error_code ec( detail::get_current_path_api( ph ) );
  if ( ec )
      boost::throw_exception( basic_filesystem_error<Path>(
        "boost::filesystem::current_path", ec ) );
  return Path( Path::traits_type::to_internal( ph ) );
}

So the function is there. I'm using it just like the examples in the boost documentation. Is there something stupid I'm missing here? If I make a path with ".", it works, but I want the full pathname, not just ".".

I have g++ 4.4.6 on RedHat enterprise 6.2, with boost 1.41.0 (I know it's old, but I don't have the option of upgrading).

Answer 1

Looking at the definition of current_path...

template< class Path > Path current_path() ...

• current_path is a function template, and the template argument type can't be inferred from its parameters (of which there are none) - so we have to explicitly provide the template argument.
• the return type of current_path() has the same type as the template argument.

The reason for this is so we can return narrow and wide character paths ie:

namespace fs = boost::filesystem;

// get the current path    
fs::path p = fs::current_path<fs::path>();

// get the current path in wide characters    
fs::wpath wp = fs::current_path<fs::wpath>();

wpath is the wide character version of path (akin to wstring and string).