Re: [boost] [winapi] Problem with the latest clang on Windows

Subject: Re: [boost] [winapi] Problem with the latest clang on Windows
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2015-06-01 21:11:36

On 2 Jun 2015 at 1:57, Andrey Semashev wrote:

> Since other than the above there are no special treatment of extern "C" 
> function calls from the language perspective, I would assume that as long as 
> the call in unambiguous by the C++ overload resolution rules, the language 
> should allow it.
> 
> If clang folks say this should not compile then perhaps they could point to 
> the relevant part of the standard.

Obviously declspec anything is non-standard.

I believe the reason clang is insisting on this behaviour is because 
declspec is part of the type definition. You can see this in how 
pointers to functions retain their declspec attributes in the pointer 
type.

Therefore not always specifying them consistently is an ODR 
violation, and therefore clang is being right here. GCC matches 
MSVC's incorrectness here for ease of life. As does clang when in 
MSVC mode.

Regarding mingw's broken headers which don't specify dllimport 
correctly for kernel32 imports, yeah that's one of a long litany of 
problems in mingw's headers. I in fact gave up on mingw support in 
AFIO in the v1.3 release, it was becoming too painful to keep working 
around their severe quality problems. AFIO now only supports 
mingw-w64.

Mingw-w64 have done an excellent job, and are light years ahead of 
mingw in quality control and stability. They also support the C++ 11 
<thread> header, which mingw does not.

Regarding why clang is not on mingw-w64 yet, apparently it may be 
political. See 
http://sourceforge.net/p/mingw-w64/mailman/mingw-w64-public/thread/873
8aihlgy.fsf_at_[hidden]/. I agree with the assessment that mingw 
support is not a priority for the clang devs compared to MSVC 
support, but I am not aware of any active campaign against mingw-w64 
support. It's more no one could be bothered relative to other things 
to do I think.

Anyway, from my own perspective whilst it would be nice if 
mingw-clang was working, it's no showstopper for me personally. MinGW 
users are a tiny proportion of the user base, sufficiently tiny that 
GCC is good enough for now. I see mingw-w64 is very shortly going to 
release a GCC 5.1 build, it's hardly like MinGW users are suffering 
from ancient GCC tooling or something.

winclang is a whole different beast though. That's an enormous threat 
to MSVC in the medium term. Microsoft may, of course, just go ahead 
and bundle a winclang toolset in future Visual Studios as an equally 
supported alternative to MSVC. That would be *enormous* for anyone 
trying to do modern C++ on Windows, though MSVC is coming along 
hugely of late and it's still vastly faster to compile than clang, 
and I suspect always will be.

Niall

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