enum_: fix implicit conversion on Python 2.7

Enumerations on Python 2.7 were not always implicitly converted to
integers (depending on the target size). This patch adds a __long__
conversion function (only enabled on 2.7) which fixes this issue.

The attached test case fails without this patch.

include/pybind11/cast.h

@@ -561,7 +561,7 @@ public:
             (std::is_integral<T>::value && sizeof(py_type) != sizeof(T) &&
                (py_value < (py_type) std::numeric_limits<T>::min() ||
                 py_value > (py_type) std::numeric_limits<T>::max()))) {
-#if PY_VERSION_HEX < 0x03000000
+#if PY_VERSION_HEX < 0x03000000 && !defined(PYPY_VERSION)
             bool type_error = PyErr_ExceptionMatches(PyExc_SystemError);
 #else
             bool type_error = PyErr_ExceptionMatches(PyExc_TypeError);

include/pybind11/pybind11.h

@@ -1197,6 +1197,9 @@ public:
         }, return_value_policy::copy);
         def("__init__", [](Type& value, Scalar i) { value = (Type)i; });
         def("__int__", [](Type value) { return (Scalar) value; });
+        #if PY_MAJOR_VERSION < 3
+            def("__long__", [](Type value) { return (Scalar) value; });
+        #endif
         def("__eq__", [](const Type &value, Type *value2) { return value2 && value == *value2; });
         def("__ne__", [](const Type &value, Type *value2) { return !value2 || value != *value2; });
         if (is_arithmetic) {

tests/test_enum.cpp

@@ -65,4 +65,8 @@ test_initializer enums([](py::module &m) {
         .value("EFirstMode", ClassWithUnscopedEnum::EFirstMode)
         .value("ESecondMode", ClassWithUnscopedEnum::ESecondMode)
         .export_values();
+
+    m.def("test_enum_to_int", [](int) { });
+    m.def("test_enum_to_uint", [](uint32_t) { });
+    m.def("test_enum_to_long_long", [](long long) { });
 });

tests/test_enum.py

@@ -115,3 +115,14 @@ def test_binary_operators():
     state2 = ~state
     assert state2 == -7
     assert int(state ^ state2) == -1
+
+def test_enum_to_int():
+    from pybind11_tests import Flags, ClassWithUnscopedEnum
+    from pybind11_tests import test_enum_to_int, test_enum_to_uint, test_enum_to_long_long
+
+    test_enum_to_int(Flags.Read)
+    test_enum_to_int(ClassWithUnscopedEnum.EMode.EFirstMode)
+    test_enum_to_uint(Flags.Read)
+    test_enum_to_uint(ClassWithUnscopedEnum.EMode.EFirstMode)
+    test_enum_to_long_long(Flags.Read)
+    test_enum_to_long_long(ClassWithUnscopedEnum.EMode.EFirstMode)