Hi, I'm trying to build Boost.Log on MSVC9 (aka Visual Studio 2008) with the [/Zc:wchar_t-][1] option (necessary due to a vendor's SDK we're using). Unfortunately this fails to build. The mentioned option turns wchar_t into a typedef to unsigned short (i.e. it's not longer a distinct type). TLDR: My question _why_ is boost::log::aux::is_character_type<wchar_t> excluded when BOOST_NO_INTRINSIC_WCHAR_T is #defined? I see no harm in including it unconditionally. For some reason however, the template meta-function boost::log::aux::is_character_type<T>'s specialisation for wchar_t is guarded by !defined(BOOST_NO_INTRINSIC_WCHAR_T) [2]. This means wchar_t is _not_ regarded as a character type and prevents instantiation of the boost::log::aux::code_convert functions [3] which are _still_ used. The only reason I can see for excluding this is to prevent a _potential_ conflict with multiple specialisations for the same type (because of the typedef nature of wchar_t). But the only other specialisation that could potentially give a conflict is the one for char16_t, and that's mandated by C++11 to be a distinct type (AFAIK the only reason why wchar_t isn't always distinct type on Windows/MSVC is because they introduced the type pre-standardisation, so I see no reason why that mistake should be repeated for char16_t). For reference, the mentioned option's usage is detected in boost by this option preventing #definition of _NATIVE_WCHAR_T_DEFINED to indicate it did this. In boost/config/compiler/visualc.hpp there's the following code:
#ifndef _NATIVE_WCHAR_T_DEFINED # define BOOST_NO_INTRINSIC_WCHAR_T #endif
[1]: https://msdn.microsoft.com/en-us/library/ms933181.aspx [2]: https://github.com/boostorg/log/blob/boost-1.59.0/include/boost/log/detail/i... [3]: https://github.com/boostorg/log/blob/boost-1.59.0/include/boost/log/detail/c... -- Met vriendelijke groet, With kind regards, Giel van Schijndel