[smart_holder] Change throw_if_uninitialized_or_disowned_holder() to also show C++ type name. (#4977)

* Change `throw_if_uninitialized_or_disowned_holder()` to also show C++ type name.

* Fix pre-commit errors.

Author: rwgk

include/pybind11/detail/smart_holder_type_casters.h

@@ -505,7 +505,7 @@ struct smart_holder_type_caster_load {
         }
         if (void_ptr == nullptr) {
             if (have_holder()) {
-                throw_if_uninitialized_or_disowned_holder();
+                throw_if_uninitialized_or_disowned_holder(typeid(T));
                 void_ptr = holder().template as_raw_ptr_unowned<void>();
             } else if (load_impl.loaded_v_h.vh != nullptr) {
                 void_ptr = load_impl.loaded_v_h.value_ptr();
@@ -548,7 +548,7 @@ struct smart_holder_type_caster_load {
         if (!have_holder()) {
             return nullptr;
         }
-        throw_if_uninitialized_or_disowned_holder();
+        throw_if_uninitialized_or_disowned_holder(typeid(T));
         holder_type &hld = holder();
         hld.ensure_is_not_disowned("loaded_as_shared_ptr");
         if (hld.vptr_is_using_noop_deleter) {
@@ -612,7 +612,7 @@ struct smart_holder_type_caster_load {
         if (!have_holder()) {
             return unique_with_deleter<T, D>(nullptr, std::unique_ptr<D>());
         }
-        throw_if_uninitialized_or_disowned_holder();
+        throw_if_uninitialized_or_disowned_holder(typeid(T));
         throw_if_instance_is_currently_owned_by_shared_ptr();
         holder().ensure_is_not_disowned(context);
         holder().template ensure_compatible_rtti_uqp_del<T, D>(context);
@@ -694,17 +694,22 @@ struct smart_holder_type_caster_load {
     holder_type &holder() const { return load_impl.loaded_v_h.holder<holder_type>(); }
 
     // have_holder() must be true or this function will fail.
-    void throw_if_uninitialized_or_disowned_holder() const {
+    void throw_if_uninitialized_or_disowned_holder(const char *typeid_name) const {
+        static const std::string missing_value_msg = "Missing value for wrapped C++ type `";
         if (!holder().is_populated) {
-            pybind11_fail("Missing value for wrapped C++ type:"
-                          " Python instance is uninitialized.");
+            throw value_error(missing_value_msg + clean_type_id(typeid_name)
+                              + "`: Python instance is uninitialized.");
         }
         if (!holder().has_pointee()) {
-            throw value_error("Missing value for wrapped C++ type:"
-                              " Python instance was disowned.");
+            throw value_error(missing_value_msg + clean_type_id(typeid_name)
+                              + "`: Python instance was disowned.");
         }
     }
 
+    void throw_if_uninitialized_or_disowned_holder(const std::type_info &type_info) const {
+        throw_if_uninitialized_or_disowned_holder(type_info.name());
+    }
+
     // have_holder() must be true or this function will fail.
     void throw_if_instance_is_currently_owned_by_shared_ptr() const {
         auto vptr_gd_ptr = std::get_deleter<pybindit::memory::guarded_delete>(holder().vptr);

tests/test_class_sh_basic.py

@@ -109,7 +109,9 @@ def test_pass_unique_ptr_disowns(pass_f, rtrn_f, expected):
     with pytest.raises(ValueError) as exc_info:
         pass_f(obj)
     assert str(exc_info.value) == (
-        "Missing value for wrapped C++ type: Python instance was disowned."
+        "Missing value for wrapped C++ type"
+        + " `pybind11_tests::class_sh_basic::atyp`:"
+        + " Python instance was disowned."
     )
 
 

tests/test_class_sh_disowning_mi.py

@@ -20,10 +20,7 @@ def is_disowned(callable_method):
     try:
         callable_method()
     except ValueError as e:
-        assert (  # noqa: PT017
-            str(e)
-            == "Missing value for wrapped C++ type: Python instance was disowned."
-        )
+        assert "Python instance was disowned" in str(e)  # noqa: PT017
         return True
     return False
 

tests/test_class_sh_mi_thunks.py

@@ -38,12 +38,8 @@ def test_get_vec_size_raw_shared(get_fn, vec_size_fn):
 def test_get_vec_size_unique(get_fn):
     obj = get_fn()
     assert m.vec_size_base0_unique_ptr(obj) == 5
-    with pytest.raises(ValueError) as exc_info:
+    with pytest.raises(ValueError, match="Python instance was disowned"):
         m.vec_size_base0_unique_ptr(obj)
-    assert (
-        str(exc_info.value)
-        == "Missing value for wrapped C++ type: Python instance was disowned."
-    )
 
 
 def test_get_shared_vec_size_unique():

tests/test_class_sh_property.py

@@ -9,23 +9,19 @@
 
 @pytest.mark.xfail("env.PYPY", reason="gc after `del field` is apparently deferred")
 @pytest.mark.parametrize("m_attr", ["m_valu_readonly", "m_valu_readwrite"])
-def test_valu_getter(msg, m_attr):
+def test_valu_getter(m_attr):
     # Reduced from PyCLIF test:
     # https://github.com/google/clif/blob/c371a6d4b28d25d53a16e6d2a6d97305fb1be25a/clif/testing/python/nested_fields_test.py#L56
     outer = m.Outer()
     field = getattr(outer, m_attr)
     assert field.num == -99
     with pytest.raises(ValueError) as excinfo:
         m.DisownOuter(outer)
-    assert msg(excinfo.value) == "Cannot disown use_count != 1 (loaded_as_unique_ptr)."
+    assert str(excinfo.value) == "Cannot disown use_count != 1 (loaded_as_unique_ptr)."
     del field
     m.DisownOuter(outer)
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(ValueError, match="Python instance was disowned") as excinfo:
         getattr(outer, m_attr)
-    assert (
-        msg(excinfo.value)
-        == "Missing value for wrapped C++ type: Python instance was disowned."
-    )
 
 
 def test_valu_setter():
@@ -85,18 +81,14 @@ def test_ptr(field_type, num_default, outer_type, m_attr, r_kind):
 
 
 @pytest.mark.parametrize("m_attr_readwrite", ["m_uqmp_readwrite", "m_uqcp_readwrite"])
-def test_uqp(m_attr_readwrite, msg):
+def test_uqp(m_attr_readwrite):
     outer = m.Outer()
     assert getattr(outer, m_attr_readwrite) is None
     field_orig = m.Field()
     field_orig.num = 39
     setattr(outer, m_attr_readwrite, field_orig)
-    with pytest.raises(ValueError) as excinfo:
+    with pytest.raises(ValueError, match="Python instance was disowned"):
         _ = field_orig.num
-    assert (
-        msg(excinfo.value)
-        == "Missing value for wrapped C++ type: Python instance was disowned."
-    )
     field_retr1 = getattr(outer, m_attr_readwrite)
     assert getattr(outer, m_attr_readwrite) is None
     assert field_retr1.num == 39

tests/test_class_sh_unique_ptr_member.py

@@ -16,12 +16,8 @@ def test_pointee_and_ptr_owner(give_up_ownership_via):
     obj = m.pointee()
     assert obj.get_int() == 213
     owner = m.ptr_owner(obj)
-    with pytest.raises(ValueError) as exc_info:
+    with pytest.raises(ValueError, match="Python instance was disowned"):
         obj.get_int()
-    assert (
-        str(exc_info.value)
-        == "Missing value for wrapped C++ type: Python instance was disowned."
-    )
     assert owner.is_owner()
     reclaimed = getattr(owner, give_up_ownership_via)()
     assert not owner.is_owner()