check for already existing enum value added; added test (#1453)

* check for already existing enum value added; added test

* added enum value name to exception message

* test for defining enum with multiple identical names moved to test_enum.cpp/py

include/pybind11/pybind11.h

@@ -1463,7 +1463,10 @@ template <typename Type> class enum_ : public class_<Type> {
     enum_& value(char const* name, Type value, const char *doc = nullptr) {
         auto v = pybind11::cast(value, return_value_policy::copy);
         this->attr(name) = v;
-        m_entries[pybind11::str(name)] = std::make_pair(v, doc);
+        auto name_converted = pybind11::str(name);
+        if (m_entries.contains(name_converted))
+            throw value_error("Enum error - element with name: " + std::string(name) + " already exists");
+        m_entries[name_converted] = std::make_pair(v, doc);
         return *this;
     }
 

tests/test_enum.cpp

@@ -68,4 +68,18 @@ TEST_SUBMODULE(enums, m) {
     m.def("test_enum_to_int", [](int) { });
     m.def("test_enum_to_uint", [](uint32_t) { });
     m.def("test_enum_to_long_long", [](long long) { });
+
+    // test_duplicate_enum_name
+    enum SimpleEnum
+    {
+        ONE, TWO, THREE
+    };
+
+    m.def("register_bad_enum", [m]() {
+        py::enum_<SimpleEnum>(m, "SimpleEnum")
+            .value("ONE", SimpleEnum::ONE)          //NOTE: all value function calls are called with the same first parameter value
+            .value("ONE", SimpleEnum::TWO)
+            .value("ONE", SimpleEnum::THREE)
+            .export_values();
+    });
 }

tests/test_enum.py

@@ -148,3 +148,9 @@ def test_enum_to_int():
     m.test_enum_to_uint(m.ClassWithUnscopedEnum.EMode.EFirstMode)
     m.test_enum_to_long_long(m.Flags.Read)
     m.test_enum_to_long_long(m.ClassWithUnscopedEnum.EMode.EFirstMode)
+
+
+def test_duplicate_enum_name():
+    with pytest.raises(ValueError) as excinfo:
+        m.register_bad_enum()
+    assert str(excinfo.value) == "Enum error - element with name: ONE already exists"