Revert "Demonstrate test_factory_constructors.py failure without functional changes from #2335"

This reverts commit ca33a80.

Author: YannickJadoul

include/pybind11/pybind11.h

@@ -1013,7 +1013,7 @@ class generic_type : public object {
     PYBIND11_OBJECT_DEFAULT(generic_type, object, PyType_Check)
 protected:
     void initialize(const type_record &rec) {
-        if (rec.scope && hasattr(rec.scope, rec.name))
+        if (rec.scope && hasattr(rec.scope, "__dict__") && rec.scope.attr("__dict__").contains(rec.name))
             pybind11_fail("generic_type: cannot initialize type \"" + std::string(rec.name) +
                           "\": an object with that name is already defined");
 
@@ -1931,7 +1931,7 @@ class exception : public object {
         std::string full_name = scope.attr("__name__").cast<std::string>() +
                                 std::string(".") + name;
         m_ptr = PyErr_NewException(const_cast<char *>(full_name.c_str()), base.ptr(), NULL);
-        if (hasattr(scope, name))
+        if (hasattr(scope, "__dict__") && scope.attr("__dict__").contains(name))
             pybind11_fail("Error during initialization: multiple incompatible "
                           "definitions with name \"" + std::string(name) + "\"");
         scope.attr(name) = *this;

tests/test_class.cpp

@@ -429,6 +429,22 @@ TEST_SUBMODULE(class_, m) {
     py::class_<Empty>(m, "Empty")
         .def(py::init<>());
 
+    // test_base_and_derived_nested_scope
+    struct BaseWithNested {
+        struct Nested {};
+    };
+
+    struct DerivedWithNested : BaseWithNested {
+        struct Nested {};
+    };
+
+    py::class_<BaseWithNested> baseWithNested_class(m, "BaseWithNested");
+    py::class_<DerivedWithNested, BaseWithNested> derivedWithNested_class(m, "DerivedWithNested");
+    py::class_<BaseWithNested::Nested>(baseWithNested_class, "Nested")
+        .def_static("get_name", []() { return "BaseWithNested::Nested"; });
+    py::class_<DerivedWithNested::Nested>(derivedWithNested_class, "Nested")
+        .def_static("get_name", []() { return "DerivedWithNested::Nested"; });
+
     // test_register_duplicate_class
     struct Duplicate {};
     struct OtherDuplicate {};

tests/test_class.py

@@ -385,6 +385,14 @@ def test_multiple_instances_with_same_pointer(capture):
     # and just completes without crashing, we're good.
 
 
+# https://github.com/pybind/pybind11/issues/1624
+def test_base_and_derived_nested_scope():
+    assert issubclass(m.DerivedWithNested, m.BaseWithNested)
+    assert m.BaseWithNested.Nested != m.DerivedWithNested.Nested
+    assert m.BaseWithNested.Nested.get_name() == "BaseWithNested::Nested"
+    assert m.DerivedWithNested.Nested.get_name() == "DerivedWithNested::Nested"
+
+
 def test_register_duplicate_class():
     import types
     module_scope = types.ModuleType("module_scope")