Now compiles on MSYS2 again.

src/directories.cc

@@ -8,6 +8,7 @@
 #include <iostream> //TODO: remove
 using namespace std; //TODO: remove
 
+#ifndef _WIN32
 namespace sigc {
   template <typename Functor>
   struct functor_trait<Functor, false> {
@@ -17,6 +18,7 @@ namespace sigc {
     typedef Functor functor_type;
   };
 }
+#endif
 
 Directories::Directories() : stop_update_thread(false) {
   DEBUG("adding treeview to scrolledwindow");

src/entrybox.cc

@@ -1,5 +1,6 @@
 #include "entrybox.h"
 
+#ifndef _WIN32
 namespace sigc {
   template <typename Functor>
   struct functor_trait<Functor, false> {
@@ -9,6 +10,7 @@ namespace sigc {
     typedef Functor functor_type;
   };
 }
+#endif
 
 std::unordered_map<std::string, std::vector<std::string> > EntryBox::entry_histories;
 

src/notebook.cc

@@ -9,6 +9,7 @@
 #include <iostream> //TODO: remove
 using namespace std; //TODO: remove
 
+#ifndef _WIN32
 namespace sigc {
   template <typename Functor>
   struct functor_trait<Functor, false> {
@@ -18,6 +19,7 @@ namespace sigc {
     typedef Functor functor_type;
   };
 }
+#endif
 
 Notebook::Notebook(Directories &directories) : Gtk::Notebook(), directories(directories) {
   Gsv::init();

src/selectiondialog.cc

@@ -1,6 +1,7 @@
 #include "selectiondialog.h"
 #include <algorithm>
 
+#ifndef _WIN32
 namespace sigc {
   template <typename Functor>
   struct functor_trait<Functor, false> {
@@ -10,6 +11,7 @@ namespace sigc {
     typedef Functor functor_type;
   };
 }
+#endif
 
 SelectionDialogBase::SelectionDialogBase(Gtk::TextView& text_view, Glib::RefPtr<Gtk::TextBuffer::Mark> start_mark, bool show_search_entry): text_view(text_view), 
 start_mark(start_mark), show_search_entry(show_search_entry), list_view_text(1, false, Gtk::SelectionMode::SELECTION_BROWSE) {

src/source.cc

@@ -11,6 +11,7 @@
 
 using namespace std; //TODO: remove
 
+#ifndef _WIN32
 namespace sigc {
   template <typename Functor>
   struct functor_trait<Functor, false> {
@@ -20,6 +21,7 @@ namespace sigc {
     typedef Functor functor_type;
   };
 }
+#endif
 
 Glib::RefPtr<Gsv::Language> Source::guess_language(const boost::filesystem::path &file_path) {
   auto language_manager=Gsv::LanguageManager::get_default();

src/tooltips.cc

@@ -1,6 +1,7 @@
 #include "tooltips.h"
 #include "singletons.h"
 
+#ifndef _WIN32
 namespace sigc {
   template <typename Functor>
   struct functor_trait<Functor, false> {
@@ -10,6 +11,7 @@ namespace sigc {
     typedef Functor functor_type;
   };
 }
+#endif
 
 Gdk::Rectangle Tooltips::drawn_tooltips_rectangle=Gdk::Rectangle();
 

src/window.cc

@@ -9,6 +9,7 @@
 #include <iostream> //TODO: remove
 using namespace std; //TODO: remove
 
+#ifndef _WIN32
 namespace sigc {
   template <typename Functor>
   struct functor_trait<Functor, false> {
@@ -18,6 +19,7 @@ namespace sigc {
     typedef Functor functor_type;
   };
 }
+#endif
 
 void Window::generate_keybindings() {
   boost::filesystem::path path(Singleton::config_dir() + "menu.xml");