nixpkgs/pkgs/development/python-modules/python-mapnik/python-mapnik_std_optional.patch

diff --git a/src/mapnik_image.cpp b/src/mapnik_image.cpp
index 9add692c9..488427b56 100644
--- a/src/mapnik_image.cpp
+++ b/src/mapnik_image.cpp
@@ -230,7 +230,7 @@ unsigned get_type(mapnik::image_any & im)
 
 std::shared_ptr<image_any> open_from_file(std::string const& filename)
 {
-    boost::optional<std::string> type = type_from_filename(filename);
+    auto type = type_from_filename(filename);
     if (type)
     {
         std::unique_ptr<image_reader> reader(get_image_reader(filename,*type));
diff --git a/src/mapnik_layer.cpp b/src/mapnik_layer.cpp
index 4fc7ea579..fbd277a81 100644
--- a/src/mapnik_layer.cpp
+++ b/src/mapnik_layer.cpp
@@ -95,7 +95,7 @@ struct layer_pickle_suite : boost::python::pickle_suite
 
 std::vector<std::string> & (mapnik::layer::*_styles_)() = &mapnik::layer::styles;
 
-void set_maximum_extent(mapnik::layer & l, boost::optional<mapnik::box2d<double> > const& box)
+void set_maximum_extent(mapnik::layer & l, std::optional<mapnik::box2d<double> > const& box)
 {
     if (box)
     {
@@ -107,7 +107,7 @@ void set_maximum_extent(mapnik::layer & l, boost::optional<mapnik::box2d<double>
     }
 }
 
-void set_buffer_size(mapnik::layer & l, boost::optional<int> const& buffer_size)
+void set_buffer_size(mapnik::layer & l, std::optional<int> const& buffer_size)
 {
     if (buffer_size)
     {
@@ -121,7 +121,7 @@ void set_buffer_size(mapnik::layer & l, boost::optional<int> const& buffer_size)
 
 PyObject * get_buffer_size(mapnik::layer & l)
 {
-    boost::optional<int> buffer_size = l.buffer_size();
+    std::optional<int> buffer_size = l.buffer_size();
     if (buffer_size)
     {
 #if PY_VERSION_HEX >= 0x03000000
diff --git a/src/mapnik_map.cpp b/src/mapnik_map.cpp
index 3587e5d8a..cfa523b03 100644
--- a/src/mapnik_map.cpp
+++ b/src/mapnik_map.cpp
@@ -105,7 +105,7 @@ mapnik::featureset_ptr query_map_point(mapnik::Map const& m, int index, double x
     return m.query_map_point(idx, x, y);
 }
 
-void set_maximum_extent(mapnik::Map & m, boost::optional<mapnik::box2d<double> > const& box)
+void set_maximum_extent(mapnik::Map & m, std::optional<mapnik::box2d<double> > const& box)
 {
     if (box)
     {
diff --git a/src/python_optional.hpp b/src/python_optional.hpp
index d690b7c51..9d86c340e 100644
--- a/src/python_optional.hpp
+++ b/src/python_optional.hpp
@@ -28,7 +28,7 @@
 #include <mapnik/util/noncopyable.hpp>
 #pragma GCC diagnostic pop
 
-// boost::optional<T> to/from converter from John Wiegley
+// std::optional<T> to/from converter from John Wiegley
 
 template <typename T, typename TfromPy>
 struct object_from_python
@@ -54,7 +54,7 @@ struct python_optional : public mapnik::util::noncopyable
 {
     struct optional_to_python
     {
-        static PyObject * convert(const boost::optional<T>& value)
+        static PyObject * convert(const std::optional<T>& value)
         {
             return (value ? boost::python::to_python_value<T>()(*value) :
                     boost::python::detail::none());
@@ -90,9 +90,9 @@ struct python_optional : public mapnik::util::noncopyable
                                     data)->storage.bytes;
 
             if (data->convertible == source)        // == None
-                new (storage) boost::optional<T>(); // A Boost uninitialized value
+                new (storage) std::optional<T>(); // A Boost uninitialized value
             else
-                new (storage) boost::optional<T>(*static_cast<T *>(data->convertible));
+                new (storage) std::optional<T>(*static_cast<T *>(data->convertible));
 
             data->convertible = storage;
         }
@@ -100,18 +100,18 @@ struct python_optional : public mapnik::util::noncopyable
 
     explicit python_optional()
     {
-        register_python_conversion<boost::optional<T>,
+        register_python_conversion<std::optional<T>,
             optional_to_python, optional_from_python>();
     }
 };
 
-// to/from boost::optional<bool>
+// to/from std::optional<bool>
 template <>
 struct python_optional<float> : public mapnik::util::noncopyable
 {
     struct optional_to_python
     {
-        static PyObject * convert(const boost::optional<float>& value)
+        static PyObject * convert(const std::optional<float>& value)
         {
             return (value ? PyFloat_FromDouble(*value) :
                     boost::python::detail::none());
@@ -133,30 +133,30 @@ struct python_optional<float> : public mapnik::util::noncopyable
                               boost::python::converter::rvalue_from_python_stage1_data * data)
         {
             using namespace boost::python::converter;
-            void * const storage = ((rvalue_from_python_storage<boost::optional<bool> > *)
+            void * const storage = ((rvalue_from_python_storage<std::optional<bool> > *)
                                     data)->storage.bytes;
             if (source == Py_None)  // == None
-                new (storage) boost::optional<float>(); // A Boost uninitialized value
+                new (storage) std::optional<float>(); // A Boost uninitialized value
             else
-                new (storage) boost::optional<float>(PyFloat_AsDouble(source));
+                new (storage) std::optional<float>(PyFloat_AsDouble(source));
             data->convertible = storage;
         }
     };
 
     explicit python_optional()
     {
-        register_python_conversion<boost::optional<float>,
+        register_python_conversion<std::optional<float>,
             optional_to_python, optional_from_python>();
     }
 };
 
-// to/from boost::optional<float>
+// to/from std::optional<float>
 template <>
 struct python_optional<bool> : public mapnik::util::noncopyable
 {
     struct optional_to_python
     {
-        static PyObject * convert(const boost::optional<bool>& value)
+        static PyObject * convert(const std::optional<bool>& value)
         {
             if (value)
             {
@@ -181,13 +181,13 @@ struct python_optional<bool> : public mapnik::util::noncopyable
                               boost::python::converter::rvalue_from_python_stage1_data * data)
         {
             using namespace boost::python::converter;
-            void * const storage = ((rvalue_from_python_storage<boost::optional<bool> > *)
+            void * const storage = ((rvalue_from_python_storage<std::optional<bool> > *)
                                     data)->storage.bytes;
             if (source == Py_None)  // == None
-                new (storage) boost::optional<bool>(); // A Boost uninitialized value
+                new (storage) std::optional<bool>(); // A Boost uninitialized value
             else
             {
-                new (storage) boost::optional<bool>(source == Py_True ? true : false);
+                new (storage) std::optional<bool>(source == Py_True ? true : false);
             }
             data->convertible = storage;
         }
@@ -195,7 +195,7 @@ struct python_optional<bool> : public mapnik::util::noncopyable
 
     explicit python_optional()
     {
-        register_python_conversion<boost::optional<bool>,
+        register_python_conversion<std::optional<bool>,
             optional_to_python, optional_from_python>();
     }
 };