error C2039: 'result_type' : is not a member of '`global namespace''

Question

My app is throwing this error:

error C2039: 'result_type' : is not a member of '`global namespace''

for this code:

void handle_read_headers(const boost::system::error_code& err, RESTClient::response& resp)
{
    if (!err)
    {
        // Process the response headers.
        std::istream response_stream(&response_);
        std::string header;
        while (std::getline(response_stream, header) && header != "\r")
            std::cout << header << "\n";
        std::cout << "\n";

        // Write whatever content we already have to output.
        if (response_.size() > 0)
            std::cout << &response_;

        (&resp)->body = "Yehey!!!";

        // Start reading remaining data until EOF.
        boost::asio::async_read(socket_, response_,
        boost::asio::transfer_at_least(1),
        boost::bind(&client::handle_read_content, this,
        boost::asio::placeholders::error, boost::ref(resp)));

    }
    else
    {
        std::cout << "Error: " << err << "\n";
    }
}

The "bound" function looks like this:

void handle_read_content(const boost::system::error_code& err, RESTClient::response& resp){}

What could be wrong in my code?

Update:

I was able to compile the code with these changes

Answer 1

According to this documentation page ReadHandler needs to take and error code as well as the number of bytes transferred.

It might be that MSVC is more picky/sensitive about the missing placeholders when invoking a bind expression.¹

Try adding the placeholder parameter to the bind:

// Start reading remaining data until EOF.
boost::asio::async_read(socket_, response_,
        boost::asio::transfer_at_least(1),
        boost::bind(&client::handle_read_content, this,
            boost::asio::placeholders::error,
            boost::asio::placeholders::bytes_transferred,
            boost::ref(resp)));

And obviously to the handler function itself too:

void handle_read_content(const boost::system::error_code& ec, size_t bytes_transferred, RESTClient::response& resp){}

Update

I have spent unreasonable amounts of effort (thanks to @qballer, @nab, and others on the live feed too!) to reproduce this in Visual Studio and got this:

For the record: that was

• Win32
• Boost 1_58_0
• openssl-1.0.2c-i386-win32
• Visual Studio 2013 Update 4

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¹ in fact I've sometimes noticed that Asio accepts slightly different signatures for handler functions using GCC (my preferred compiler). I've always wondered whether that is a feature, or perhaps a bug?