pybind11::memoryview in function

[KulinduC]

I'm trying to take in a py::memoryview as a parameter to a function and I try to bind the function to my module but I keep getting a deleted function error under the argument loader constructor during compilation.

I've provided a minimal code where the error comes up. The goal of my binding code is to fill a buffer that's created in C++ in Python without copy.

#include <pybind11/pybind11.h>
#include <pybind11/numpy.h>


namespace py = pybind11;
int ex(py::memoryview buffer) { return 0; }

PYBIND11_MODULE(mpi_ex, m) {
    m.def("ex",&ex, "Example test for py::memoryview");
}

The error message is as follows using gcc/11.2.0 and pybind11/2.8.1

In file included from /users/coorak/pybind_mpi/memoryview_test.cpp:1:
/opt/scorec/spack/v0181_2/install/linux-rhel7-x86_64/gcc-7.4.0/py-pybind11-2.8.1-7m3qjw5ijpih6coejwhzsstqrumztmvy/include/pybind11/pybind11.h: In instantiation of 'void pybind11::cpp_function::initialize(Func&&, Return (*)(Args ...), const Extra& ...) [with Func = int (*&)(pybind11::memoryview); Return = int; Args = {pybind11::memoryview}; Extra = {pybind11::name, pybind11::scope, pybind11::sibling, char [32]}]':
/opt/scorec/spack/v0181_2/install/linux-rhel7-x86_64/gcc-7.4.0/py-pybind11-2.8.1-7m3qjw5ijpih6coejwhzsstqrumztmvy/include/pybind11/pybind11.h:92:19:   required from 'pybind11::cpp_function::cpp_function(Return (*)(Args ...), const Extra& ...) [with Return = int; Args = {pybind11::memoryview}; Extra = {pybind11::name, pybind11::scope, pybind11::sibling, char [32]}]'
/opt/scorec/spack/v0181_2/install/linux-rhel7-x86_64/gcc-7.4.0/py-pybind11-2.8.1-7m3qjw5ijpih6coejwhzsstqrumztmvy/include/pybind11/pybind11.h:1012:22:   required from 'pybind11::module_& pybind11::module_::def(const char*, Func&&, const Extra& ...) [with Func = int (*)(pybind11::memoryview); Extra = {char [32]}]'
/users/coorak/pybind_mpi/memoryview_test.cpp:44:10:   required from here
/opt/scorec/spack/v0181_2/install/linux-rhel7-x86_64/gcc-7.4.0/py-pybind11-2.8.1-7m3qjw5ijpih6coejwhzsstqrumztmvy/include/pybind11/pybind11.h:211:21: error: use of deleted function 'pybind11::detail::argument_loader<pybind11::memoryview>::argument_loader()'
  211 |             cast_in args_converter;
      |                     ^~~~~~~~~~~~~~
In file included from /opt/scorec/spack/v0181_2/install/linux-rhel7-x86_64/gcc-7.4.0/py-pybind11-2.8.1-7m3qjw5ijpih6coejwhzsstqrumztmvy/include/pybind11/attr.h:13,
                 from /opt/scorec/spack/v0181_2/install/linux-rhel7-x86_64/gcc-7.4.0/py-pybind11-2.8.1-7m3qjw5ijpih6coejwhzsstqrumztmvy/include/pybind11/pybind11.h:13,
                 from /users/coorak/pybind_mpi/memoryview_test.cpp:1:
/opt/scorec/spack/v0181_2/install/linux-rhel7-x86_64/gcc-7.4.0/py-pybind11-2.8.1-7m3qjw5ijpih6coejwhzsstqrumztmvy/include/pybind11/cast.h:1163:7: note: 'pybind11::detail::argument_loader<pybind11::memoryview>::argument_loader()' is implicitly deleted because the default definition would be ill-formed:
 1163 | class argument_loader {