[C++-sig] errors compiling Boost Python example
Ralf Grosse-Kunstleve
rwgk at google.com
Thu Jul 5 16:57:28 CEST 2012
It looks like you inserted an extra const (I don't see it in the current
tutorial) ...
char const * const greet() {
It should work if you remove it.
Ralf
On Thu, Jul 5, 2012 at 3:21 AM, Joel Uckelman <uckelman at nomic.net> wrote:
> I'm trying to compile the example from the Boost Python docs without
> success.
>
> hello.cpp:
>
> #include <boost/python.hpp>
>
> char const * const greet() {
> return "hello, world";
> }
>
> BOOST_PYTHON_MODULE(hello_ext) {
> using namespace boost::python;
> def("greet", greet);
> }
>
> I have Boost 1.48, Python 2.7, and gcc 4.7.0.
>
> When I do this:
>
> g++ -fPIC -I/usr/include/python2.7 -c -o hello.o hello.cpp
>
> I get the following errors:
>
> In file included from
> /usr/include/boost/preprocessor/iteration/detail/iter/forward1.hpp:47:0,
> from /usr/include/boost/python/detail/invoke.hpp:63,
> from /usr/include/boost/python/detail/caller.hpp:16,
> from
> /usr/include/boost/python/object/function_handle.hpp:8,
> from
> /usr/include/boost/python/converter/arg_to_python.hpp:19,
> from /usr/include/boost/python/call.hpp:15,
> from /usr/include/boost/python/object_core.hpp:14,
> from /usr/include/boost/python/args.hpp:25,
> from /usr/include/boost/python.hpp:11,
> from hello.cpp:1:
> /usr/include/boost/python/detail/invoke.hpp: In instantiation of
> ‘PyObject*
> boost::python::detail::invoke(boost::python::detail::invoke_tag_<false,
> false>, const RC&, F&) [with RC =
> boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const
> char* const>; F = const char* const (*)(); PyObject = _object]’:
> /usr/include/boost/python/detail/caller.hpp:223:13: required from
> ‘PyObject* boost::python::detail::caller_arity<0u>::impl<F, Policies,
> Sig>::operator()(PyObject*, PyObject*) [with F = const char* const (*)();
> Policies = boost::python::default_call_policies; Sig =
> boost::mpl::vector1<const char* const>; PyObject = _object]’
> /usr/include/boost/python/object/py_function.hpp:38:33: required from
> ‘PyObject*
> boost::python::objects::caller_py_function_impl<Caller>::operator()(PyObject*,
> PyObject*) [with Caller = boost::python::detail::caller<const char* const
> (*)(), boost::python::default_call_policies, boost::mpl::vector1<const
> char* const> >; PyObject = _object]’
> hello.cpp:10:1: required from here
> /usr/include/boost/python/detail/invoke.hpp:75:19: error: no match for
> call to ‘(const
> boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const
> char* const>) (const char*)’
> In file included from
> /usr/include/boost/python/object/function_handle.hpp:8:0,
> from
> /usr/include/boost/python/converter/arg_to_python.hpp:19,
> from /usr/include/boost/python/call.hpp:15,
> from /usr/include/boost/python/object_core.hpp:14,
> from /usr/include/boost/python/args.hpp:25,
> from /usr/include/boost/python.hpp:11,
> from hello.cpp:1:
> /usr/include/boost/python/detail/caller.hpp: In instantiation of ‘static
> const PyTypeObject*
> boost::python::detail::converter_target_type<ResultConverter>::get_pytype()
> [with ResultConverter =
> boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const
> char* const>; PyTypeObject = _typeobject]’:
> /usr/include/boost/python/detail/caller.hpp:242:13: required from
> ‘static boost::python::detail::py_func_sig_info
> boost::python::detail::caller_arity<0u>::impl<F, Policies,
> Sig>::signature() [with F = const char* const (*)(); Policies =
> boost::python::default_call_policies; Sig = boost::mpl::vector1<const char*
> const>]’
> /usr/include/boost/python/object/py_function.hpp:48:35: required from
> ‘boost::python::detail::py_func_sig_info
> boost::python::objects::caller_py_function_impl<Caller>::signature() const
> [with Caller = boost::python::detail::caller<const char* const (*)(),
> boost::python::default_call_policies, boost::mpl::vector1<const char*
> const> >]’
> hello.cpp:10:1: required from here
> /usr/include/boost/python/detail/caller.hpp:102:109: error: ‘struct
> boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const
> char* const>’ has no member named ‘get_pytype’
> In file included from
> /usr/include/boost/python/converter/pytype_function.hpp:10:0,
> from /usr/include/boost/python/to_python_indirect.hpp:16,
> from
> /usr/include/boost/python/converter/arg_to_python.hpp:10,
> from /usr/include/boost/python/call.hpp:15,
> from /usr/include/boost/python/object_core.hpp:14,
> from /usr/include/boost/python/args.hpp:25,
> from /usr/include/boost/python.hpp:11,
> from hello.cpp:1:
> /usr/include/boost/python/detail/unwind_type.hpp: In instantiation of
> ‘typename Generator::result_type
> boost::python::detail::unwind_type(boost::type<U>*, Generator*) [with
> Generator = boost::python::converter::detail::unwind_type_id_helper; U =
> const char* const; typename Generator::result_type =
> boost::python::type_info]’:
> /usr/include/boost/python/converter/pytype_function.hpp:45:74: required
> from ‘boost::python::type_info
> boost::python::converter::detail::unwind_type_id_(boost::type<T>*,
> mpl_::false_*) [with T = const char* const; mpl_::false_ =
> mpl_::bool_<false>]’
> /usr/include/boost/python/converter/pytype_function.hpp:68:13: required
> from ‘static const PyTypeObject*
> boost::python::converter::expected_pytype_for_arg<T>::get_pytype() [with T
> = const char* const; PyTypeObject = _typeobject]’
> /usr/include/boost/python/detail/signature.hpp:98:13: required from
> ‘static const boost::python::detail::signature_element*
> boost::python::detail::signature_arity<0u>::impl<Sig>::elements() [with Sig
> = boost::mpl::vector1<const char* const>]’
> /usr/include/boost/python/detail/caller.hpp:232:78: required from
> ‘static boost::python::detail::py_func_sig_info
> boost::python::detail::caller_arity<0u>::impl<F, Policies,
> Sig>::signature() [with F = const char* const (*)(); Policies =
> boost::python::default_call_policies; Sig = boost::mpl::vector1<const char*
> const>]’
> /usr/include/boost/python/object/py_function.hpp:48:35: required from
> ‘boost::python::detail::py_func_sig_info
> boost::python::objects::caller_py_function_impl<Caller>::signature() const
> [with Caller = boost::python::detail::caller<const char* const (*)(),
> boost::python::default_call_policies, boost::mpl::vector1<const char*
> const> >]’
> hello.cpp:10:1: required from here
> /usr/include/boost/python/detail/unwind_type.hpp:165:72: error: no
> matching function for call to
> ‘boost::python::detail::unwind_helper2<1>::execute(const char* const (*)(),
> boost::python::converter::detail::unwind_type_id_helper*)’
> /usr/include/boost/python/detail/unwind_type.hpp:165:72: note: candidate
> is:
> In file included from
> /usr/include/boost/python/converter/pytype_function.hpp:10:0,
> from /usr/include/boost/python/to_python_indirect.hpp:16,
> from
> /usr/include/boost/python/converter/arg_to_python.hpp:10,
> from /usr/include/boost/python/call.hpp:15,
> from /usr/include/boost/python/object_core.hpp:14,
> from /usr/include/boost/python/args.hpp:25,
> from /usr/include/boost/python.hpp:11,
> from hello.cpp:1:
> /usr/include/boost/python/detail/unwind_type.hpp:114:5: note:
> template<class Generator, class U> static typename Generator::result_type
> boost::python::detail::unwind_helper2<1>::execute(U* (*)(), Generator*)
> /usr/include/boost/python/detail/unwind_type.hpp:114:5: note: template
> argument deduction/substitution failed:
> In file included from
> /usr/include/boost/python/converter/pytype_function.hpp:10:0,
> from /usr/include/boost/python/to_python_indirect.hpp:16,
> from
> /usr/include/boost/python/converter/arg_to_python.hpp:10,
> from /usr/include/boost/python/call.hpp:15,
> from /usr/include/boost/python/object_core.hpp:14,
> from /usr/include/boost/python/args.hpp:25,
> from /usr/include/boost/python.hpp:11,
> from hello.cpp:1:
> /usr/include/boost/python/detail/unwind_type.hpp:165:72: note: types
> ‘U*’ and ‘const char* const’ have incompatible cv-qualifiers
>
>
>
> It looks like the salient error is this one:
>
> /usr/include/boost/python/detail/invoke.hpp:75:19: error: no match for
> call to ‘(const
> boost::python::detail::specify_a_return_value_policy_to_wrap_functions_returning<const
> char* const>) (const char*)’
>
> but the Boost Python tutorial didn't mention the need to specify a
> return value policy for the "hello world" example.
>
> So, I suppose this is either
>
> a) a bug in Boost Python,
> b) a bug in the Boost Python tutorial I copied from, or
> c) a mistake I'm making
>
> Does anyone see which?
>
> --
> J.
>
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