New test_class_sh_property_bakein.py

Use cases in the wild:

* `test_readonly_char6_member()`: https://github.com/pytorch/pytorch/blob/4410c44ae6fd8eb36f2358ac76f7d988ca7537c5/torch/csrc/cuda/Module.cpp#L961

* `test_readonly_const_char_ptr_member()`: https://github.com/facebookresearch/nle/blob/862a439a84f52abca94d1f744d57061da12c5831/include/permonst.h#L43

Author: rwgk

include/pybind11/pybind11.h

@@ -1636,7 +1636,7 @@ struct property_cpp_function<
     D,
     detail::enable_if_t<
         detail::all_of<std::is_base_of<detail::type_caster_base<T>, detail::type_caster<T>>,
-                       std::is_base_of<detail::type_caster_base<D>, detail::type_caster<D>>,
+                       std::is_base_of<detail::type_caster_base<D>, detail::make_caster<D>>,
                        std::is_pointer<D>>::value>> {
 
     using drp = typename std::remove_pointer<D>::type;
@@ -1686,6 +1686,7 @@ struct property_cpp_function<
         detail::all_of<std::is_base_of<detail::type_caster_base<T>, detail::type_caster<T>>,
                        std::is_base_of<detail::type_caster_base<D>, detail::type_caster<D>>,
                        detail::none_of<std::is_pointer<D>,
+                                       std::is_array<D>,
                                        detail::is_instantiation<std::unique_ptr, D>,
                                        detail::is_instantiation<std::shared_ptr, D>>>::value>> {
 

tests/CMakeLists.txt

@@ -127,6 +127,7 @@ set(PYBIND11_TEST_FILES
     test_class_sh_mi_thunks
     test_class_sh_module_local.py
     test_class_sh_property
+    test_class_sh_property_bakein
     test_class_sh_property_non_owning
     test_class_sh_shared_ptr_copy_move
     test_class_sh_trampoline_basic

tests/test_class_sh_property_bakein.cpp

@@ -0,0 +1,26 @@
+#include "pybind11_tests.h"
+
+namespace test_class_sh_property_bakein {
+
+struct WithCharArrayMember {
+    WithCharArrayMember() { std::strcpy(char6_member, "Char6"); }
+    char char6_member[6];
+};
+
+struct WithConstCharPtrMember {
+    const char *const_char_ptr_member = "ConstChar*";
+};
+
+} // namespace test_class_sh_property_bakein
+
+TEST_SUBMODULE(class_sh_property_bakein, m) {
+    using namespace test_class_sh_property_bakein;
+
+    py::class_<WithCharArrayMember>(m, "WithCharArrayMember")
+        .def(py::init<>())
+        .def_readonly("char6_member", &WithCharArrayMember::char6_member);
+
+    py::class_<WithConstCharPtrMember>(m, "WithConstCharPtrMember")
+        .def(py::init<>())
+        .def_readonly("const_char_ptr_member", &WithConstCharPtrMember::const_char_ptr_member);
+}

tests/test_class_sh_property_bakein.py

@@ -0,0 +1,13 @@
+from __future__ import annotations
+
+from pybind11_tests import class_sh_property_bakein as m
+
+
+def test_readonly_char6_member():
+    obj = m.WithCharArrayMember()
+    assert obj.char6_member == "Char6"
+
+
+def test_readonly_const_char_ptr_member():
+    obj = m.WithConstCharPtrMember()
+    assert obj.const_char_ptr_member == "ConstChar*"