[kroplabeskidu]

Description

Fixes #5853. Calling .value() twice with the same name on a py::native_enum fails inside enum.Enum(...) with a message that names neither the enum nor the binding:

TypeError: 'dup' already defined as 0

During module init this ends up as ImportError: initialization failed, which makes the duplicate hard to find. finalize() now checks for duplicates first and uses the same format as the other native_enum errors:

pybind11::native_enum<...>("fake_native_enum_duplicate_value_name").value("dup"): an object with that name is already defined

The check runs once in finalize() using a set, so it doesn't make .value() quadratic for large enums.

Suggested changelog entry:

• py::native_enum now names the enum and member when a member name is registered twice.