Support lvalue conversion of enum_ to handle

Author: aldanor

include/pybind11/pybind11.h

@@ -1274,6 +1274,10 @@ template <typename Type> class enum_ {
         return cls;
     }
 
+    operator handle() & {
+        return cls;
+    }
+
 private:
     class_<Type> cls;
     dict m_entries;

tests/test_enum.cpp

@@ -44,7 +44,7 @@ std::string test_scoped_enum(ScopedEnum z) {
 test_initializer enums([](py::module &m) {
     m.def("test_scoped_enum", &test_scoped_enum);
 
-    py::enum_<UnscopedEnum>(m, "UnscopedEnum", py::arithmetic())
+    auto e = py::enum_<UnscopedEnum>(m, "UnscopedEnum", py::arithmetic())
         .value("EOne", EOne)
         .value("ETwo", ETwo)
         .export_values()
@@ -59,6 +59,8 @@ test_initializer enums([](py::module &m) {
         .value("Two", ScopedEnum::Two)
         .value("Three", ScopedEnum::Three);
 
+    py::setattr(e, "Alias", scoped_enum);
+
     py::enum_<Flags>(m, "Flags", py::arithmetic())
         .value("Read", Flags::Read)
         .value("Write", Flags::Write)

tests/test_enum.py

@@ -40,6 +40,11 @@ def test_unscoped_enum():
     assert not (2 < UnscopedEnum.EOne)
 
 
+def test_enum_as_handle():
+    from pybind11_tests import UnscopedEnum, ScopedEnum
+    assert UnscopedEnum.Alias is ScopedEnum
+
+
 def test_extra_defs():
     from pybind11_tests import UnscopedEnum
     assert UnscopedEnum.EOne.x() == 2 and UnscopedEnum.ETwo.x() == 3