Re: [boost] [winapi] [thread] Conflicting declarations on MinGW

Subject: Re: [boost] [winapi] [thread] Conflicting declarations on MinGW
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2015-12-31 09:32:49

On 2015-12-31 15:47, Agustín K-ballo Bergé wrote:
> On 12/31/2015 7:59 AM, Andrey Semashev wrote:
>> On 2015-12-31 13:40, Antony Polukhin wrote:
>>> Hi,
>>>
>>> Some of the Boost.DLL tests produce following warnings:
>>>
>>> ../boost/thread/win32/thread_primitives.hpp:175:83: warning:
>>> declaration of
>>> 'void* boost::detail::win32::GetModuleHandleA(const char*)' with C
>>> language
>>> linkage
>>> ../boost/detail/winapi/dll.hpp:47:1: warning: conflicts with previous
>>> declaration 'HINSTANCE__*
>>> GetModuleHandleA(boost::detail::winapi::LPCSTR_)'
>>> ../boost/thread/win32/thread_primitives.hpp:195:94: warning:
>>> declaration of
>>> 'int (__attribute__((__stdcall__)) *
>>> boost::detail::win32::GetProcAddress(void*, const char*))()' with C
>>> language linkage
>>> ../boost/detail/winapi/dll.hpp:82:1: warning: conflicts with previous
>>> declaration 'int (__attribute__((__stdcall__)) *
>>> GetProcAddress(boost::detail::winapi::HMODULE_,
>>> boost::detail::winapi::LPCSTR_))()'
>>>
>>>
>>> Andrey, Vicente what's the best way to resolve such issues?
>>
>> IMO, Boost.Thread needs to be ported to Boost.WinAPI.
>> boost/thread/win32/thread_primitives.hpp declares extern "C" functions
>> in its own namespace, while Windows SDK and Boost.WinAPI declare them in
>> the global namespace.
>
> Declaring extern "C" functions in a namespace is perfectly fine.
> Frankly, I'm surprised and disappointed that Boost.WinAPI does not do
> it, and that it will litter the global namespace instead.

It did, until it caused problems with clang - similar to the ones quoted 
by Antony above.

> The warning comes from the use of different arguments and/or return type
> in the declarations. I'm guessing Boost.WinAPI is using winapi's typed
> handles, while we can see in the warning message that Boost.Thread uses
> just `void`.

The types in Boost.WinAPI are the same as the ones in Windows SDK (sans 
the typedefs, which I assume are not essential). There are no structs in 
the mentioned functions, and as far as I can see the types in 
Boost.Thread are also the same. So the only difference seems to be the 
namespace in which the functions are declared.