Re: [boost] Clang 4.0.0 MPL error in Boost next.hpp and prior.hpp

Subject: Re: [boost] Clang 4.0.0 MPL error in Boost next.hpp and prior.hpp
From: degski (degski_at_[hidden])
Date: 2017-03-25 14:26:54

On 25 March 2017 at 05:17, Peter Dimov via Boost <boost_at_[hidden]>
wrote:

> I have no idea why we have two clang toolsets, or which would be the
> correct one to use here.

 Because there ARE (at least) two, the Clang-msvc option is (for the
moment) a dead end, though.

@Paul: Edward and Niall have looked into this extensively (there's a few
threads on this on the mailing list, around April 2016) and nothing
(obvious) seems to work (even after getting the build to start) as a mix of
'errors' in Clang-cl's VC-PP emulation goes together with
mis-identification of the Clang/LLVM/C2/VC-STL combo in the boost-headers
(possibly clang-cl is the culprit, what -fno-ms-compatibility tries to
solve, but it doesn't) starting with type-traits and typeof (but not
limited to), which then avalache through the rest of the boost-code. On the
bright side, if it doesn't work, there's no need for testing either :-) .

Both Niall and Edward have submitted several PR's to Clang, which seem to
be ignored. Edward seems to think it's just to big a mess to fix for the
Clang team.

Without some fixes to type-traits and typeof, one cannot use clang-cl
successfully for code that contains boost library headers, even when
linking to boost libraries compiled with vanilla VC.

It might be that either Niall or Edward has made progress on this subject,
but I'm not aware of that.

degski