id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
6145	MinGW / GCC 4.6.1 warns about conflicts between Boost.Thread and Boost.InterProcess (Win32 C API)	Cyril Othenin-Girard <cog@…>	Ion Gaztañaga	"I compile boost-1.48 with GCC 4.6.1 using MinGW-32 3.10 on Windows XP.

My compiling options are :
{{{
g++ -std=c++0x
}}}

I encounter the following conflicts :

{{{
~/boost-1.48/interprocess/detail/win32_api.hpp:808:116: warning: declaration of 'void* boost::interprocess::winapi::CreateMutexA(boost::interprocess::winapi::interprocess_security_attributes*, int, const char*)' with C language linkage [enabled by default]
~/boost-1.48/thread/win32/thread_primitives.hpp:119:55: warning: conflicts with previous declaration 'void* boost::detail::win32::CreateMutexA(boost::detail::win32::_SECURITY_ATTRIBUTES*, int, const char*)' [enabled by default]
}}}
{{{
~/boost-1.48/interprocess/detail/win32_api.hpp:813:127: warning: declaration of 'void* boost::interprocess::winapi::CreateSemaphoreA(boost::interprocess::winapi::interprocess_security_attributes*, long int, long int, const char*)' with C language linkage [enabled by default]
~/boost-1.48/thread/win32/thread_primitives.hpp:120:55: warning: conflicts with previous declaration 'void* boost::detail::win32::CreateSemaphoreA(boost::detail::win32::_SECURITY_ATTRIBUTES*, long int, long int, const char*)' [enabled by default]
}}}

The problem looks like closed tickets #4217 and #5030.

It looks like ""extern C"" modifier make the compiler to ignore namespace declarations, hence the conflicts.

For example, discarding namespaces, '''Boost.Thread''' declares CreateMutexA() like this :
{{{
extern ""C""
{
    struct _SECURITY_ATTRIBUTES;
    __declspec(dllimport) void* __stdcall CreateMutexA('''boost::detail::win32::_SECURITY_ATTRIBUTES'''*,int,char const*);
}
}}}
whereas '''Boost.Interprocess''' declares it like this :
{{{
struct interprocess_security_attributes
{
   unsigned long nLength;
   void *lpSecurityDescriptor;
   int bInheritHandle;
};
extern ""C"" __declspec(dllimport) void * __stdcall CreateMutexA('''boost::interprocess::winapi::interprocess_security_attributes'''*, int, const char *);
}}}

To avoid the compiler warnings, the same type should be used for the first parameter of CreateMutexA()."	Bugs	new	To Be Determined	interprocess	Boost 1.48.0	Problem		MinGW interprocess thread warning conflict