Conflict with Boost.

[acdemiralp]

Hello, the following function (and any similar one which defines placeholders such as _1 ...) conflicts with boost::placeholders::_1 and produces warnings.

#define TROMPELOEIL_WITH_(capture, arg_s, ...)                                 \
  with(arg_s, [capture](auto const& trompeloeil_x) {                           \
    auto& _1 = ::trompeloeil::mkarg<1>(trompeloeil_x);                         \
    auto& _2 = ::trompeloeil::mkarg<2>(trompeloeil_x);                         \
    auto& _3 = ::trompeloeil::mkarg<3>(trompeloeil_x);                         \
    auto& _4 = ::trompeloeil::mkarg<4>(trompeloeil_x);                         \
    auto& _5 = ::trompeloeil::mkarg<5>(trompeloeil_x);                         \
    auto& _6 = ::trompeloeil::mkarg<6>(trompeloeil_x);                         \
    auto& _7 = ::trompeloeil::mkarg<7>(trompeloeil_x);                         \
    auto& _8 = ::trompeloeil::mkarg<8>(trompeloeil_x);                         \
    auto& _9 = ::trompeloeil::mkarg<9>(trompeloeil_x);                         \
    auto&_10 = ::trompeloeil::mkarg<10>(trompeloeil_x);                        \
    auto&_11 = ::trompeloeil::mkarg<11>(trompeloeil_x);                        \
    auto&_12 = ::trompeloeil::mkarg<12>(trompeloeil_x);                        \
    auto&_13 = ::trompeloeil::mkarg<13>(trompeloeil_x);                        \
    auto&_14 = ::trompeloeil::mkarg<14>(trompeloeil_x);                        \
    auto&_15 = ::trompeloeil::mkarg<15>(trompeloeil_x);                        \
    ::trompeloeil::ignore(_1,_2,_3,_4,_5,_6,_7,_8,_9,_10,_11,_12,_13,_14,_15); \
    return __VA_ARGS__;                                                        \
  })

The produced error is "Declaration of _... hides global declaration":

[rollbear]

Can you show a small stand alone test program that exposes this problem? On the face of it, I don't understand why there would be a conflict, and my small experiment compiled and worked.

Also, which compiler are you using? (MSVC, it looks like, but which version?)

Or is "blendet globale Deklaration" to say that it warns that there may be a misunderstanding about which _1 is meant, even though the C++ rules are clear? (I'm afraid my German was terrible 30 years ago, and has not improved with time.) If so, I fear there's not much I can do. It should also complain that boost _1 is in conflict with std::placeholders. Does it? What happens if you include both <boost/bind/placeholders.h> and , and use std::bind?

[tomvierjahn]

It should be MSVC from Visual Studio 2017 (15.3.409.57025)

English warning text: warning C4459: declaration of '_1' hides global declaration

[tomvierjahn]

We have resolved the issue on our side.

For the record:
We are using boost/signals2/connection.hpp and boost/signals2/signal.hpp. The former indirectly includes boost/bind.hpp. Then, boost/bind.hpp places the boost placeholders into global namespace.

Defining BOOST_BIND_NO_PLACEHOLDERS prior to including boost/signals2/connection.hpp and therefore prior to including boost/bind.hpp resolves this issue.