unresolved overloaded function type

void Graph::show_edge(void (*visit)(const string&, const string&)) const
{
    for(size_t i = 0; i < m_edge.size(); i++)
        for(size_t j = 0; j < m_edge[i].size(); j++)
            if(m_edge[i][j])
                visit(get_vertex(i), get_vertex(j));
}

else if(boost::regex_match(lineEdit->text().toStdString(), show_vertex))
     {
         pm_graph->show_edge([this](const string& str1, const string& str2)
         {
             pm_show->text_label("Вершина ");
             pm_show->text_label(QString::fromStdString(str1));
             pm_show->text_label(" смежна с вершиной ");
             pm_show->text_label(QString::fromStdString(str2));
             pm_show->text_label("\n");
         });
         pm_show->show_scroll();
     }

void visit(const string& str1, const string& str2)
    {
        pm_show->text_label("Вершина ");
        pm_show->text_label(QString::fromStdString(str1));
        pm_show->text_label(" смежна с вершиной ");
        pm_show->text_label(QString::fromStdString(str2));
        pm_show->text_label("\n");
    }

else if(boost::regex_match(lineEdit->text().toStdString(), show_vertex))
     {
         pm_graph->show_edge(visit);
         pm_show->show_scroll();
     }