[boost] [thread] fails to build on Cygwin with weird errors

Vicente, I'm trying to get the pool tests up and running (they fail across the board, at least on develop), and one of them requires Thread, which fails to build under g++/Cygwin. The errors are of the kind ..\..\..\libs\thread\src\win32\thread.cpp: In member function 'bool boost::thread::start_thread_noexcept()': ..\..\..\libs\thread\src\win32\thread.cpp:337:127: error: 'struct boost::detail::thread_data_base' has no member named 'id' uintptr_t const new_thread=_beginthreadex(0,0,&thread_start_function,thread_info.get(),CREATE_SUSPENDED,&thread_info->id); which leads me to think that, on Cygwin, you're using the POSIX header with the Win32 source file.