Hi
I'm using the type erasure library but have an issue (which I can workaround)
when compiling in Windows 10 using Embarcadero C++ Builder 11.3.
My problem is that C++ Builder brings in the Windows SDK Windows.h include file
in every Windows VCL UI project it creates *before* any of my code has compiled
and it's causing conflicts in boost header member11.hpp.
This code is enough to cause the error:
#include <boost/type_erasure/any.hpp>
#include <boost/type_erasure/any_cast.hpp>
#include <boost/type_erasure/builtin.hpp>
#include <boost/type_erasure/operators.hpp>
#include <boost/type_erasure/member.hpp>
#include <boost/type_erasure/free.hpp>
#include <boost/mpl/vector.hpp>
namespace mynamespace {
BOOST_TYPE_ERASURE_MEMBER(ReadStatus)
}
The error is because Windows.h defines 'interface' but this code from
member11.hpp also uses 'interface':
template<class P, template<class ...> class interface, class Sig, class
Concept, class Base, class ID>
using choose_member_interface = typename ::boost::mpl::if_c<
::boost::is_reference<P>::value,
typename ::boost::mpl::if_c<
::boost::type_erasure::detail::is_non_const_ref<P>::value,
interface<Sig, Concept, Base, const ID>,
Base
>::type,
interface<Sig, Concept, Base, ID>
>::type;
and the compiler complains of conflicts.
Embarcadero support have told me that I can't prevent Windows.h being included
in my project before my boost-using code is compiled and attempts I've made to
circumvent the problem, such as adding these lines to codegear.hpp:
#ifdef interface
#undef interface
#endif
don't work because C++ Builder is still including Windows.h before my code is
compiled.
To get around the problem, I changed member11.hpp in my boost installation to
template<class P, template<class ...> class interface_, class Sig, class
Concept, class Base, class ID>
using choose_member_interface = typename ::boost::mpl::if_c<
::boost::is_reference<P>::value,
typename ::boost::mpl::if_c<
::boost::type_erasure::detail::is_non_const_ref<P>::value,
interface_<Sig, Concept, Base, const ID>,
Base
>::type,
interface_<Sig, Concept, Base, ID>
>::type;
which I don't think will have side effects as 'interface/interface_' here is
self-contained, but it doesn't feel like a good long term solution. Embarcadero
support said:
"Boost brings windows.h in because boost pulls it, *IF* the application is
compiled for multi-threading then boost needs to access the OS threading
functions, this is when you compile *without* the VCL."
and I have confirmed this by creating a simple, multi-threaded Windows console
application in C++ Builder...
My question is: Is there a better way to work around this issue? My tests
indicate that the Type Erasure library is working properly with my change, but
it feels more like a hack than a fix...
Thanks,
Andy Bell
Control Systems & Software Engineer
Tel: +44 (0)1903 891700
Fax: +44 (0)1903 893888
Web: www.thermcosystems.com<http://www.thermcosystems.com/>
www.csd-epi.com<http://www.csd-epi.com/>
[cid:[email protected]]
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