[smart_holder] Make smart holder type caster of unique_ptr accept automatic_reference

include/pybind11/detail/smart_holder_type_casters.h

@@ -965,6 +965,7 @@ struct smart_holder_type_caster<std::unique_ptr<T, D>> : smart_holder_type_caste
 
     static handle cast(std::unique_ptr<T, D> &&src, return_value_policy policy, handle parent) {
         if (policy != return_value_policy::automatic
+            && policy != return_value_policy::automatic_reference
             && policy != return_value_policy::reference_internal
             && policy != return_value_policy::move
             && policy != return_value_policy::_clif_automatic) {

tests/test_class_sh_basic.cpp

@@ -160,6 +160,12 @@ TEST_SUBMODULE(class_sh_basic, m) {
     m.def("args_shared_ptr_const", [](std::shared_ptr<atyp const> p) { return p; });
     m.def("args_unique_ptr", [](std::unique_ptr<atyp> p) { return p; });
     m.def("args_unique_ptr_const", [](std::unique_ptr<atyp const> p) { return p; });
+
+    // Make sure unique_ptr type caster accept automatic_reference return value policy.
+    m.def(
+        "rtrn_uq_automatic_reference",
+        []() { return std::unique_ptr<atyp>(new atyp("rtrn_uq_automatic_reference")); },
+        pybind11::return_value_policy::automatic_reference);
 }
 
 } // namespace class_sh_basic

tests/test_class_sh_basic.py

@@ -181,3 +181,7 @@ def test_function_signatures(doc):
         doc(m.args_unique_ptr_const)
         == "args_unique_ptr_const(arg0: m.class_sh_basic.atyp) -> m.class_sh_basic.atyp"
     )
+
+
+def test_unique_ptr_return_value_policy_automatic_reference():
+    assert m.get_mtxt(m.rtrn_uq_automatic_reference()) == "rtrn_uq_automatic_reference"