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: Edward Diener (eldiener_at_[hidden])
Date: 2017-03-26 03:46:51

On 3/25/2017 4:37 PM, Peter Dimov via Boost wrote:
> Edward Diener wrote:
> On 3/25/2017 12:46 PM, Peter Dimov via Boost wrote:
>> > Well given that BOOST_PP_VARIADICS_MSVC=0 works at least some of the
>> > time and BOOST_PP_VARIADICS_MSVC=1 never works, it seems to me that
>> the > choice is a rather easy one and does not depend on any
>> predefined > macros.
>>
>> I am not sure what you are saying here:
>>
>> 1) Are you saying that turning off BOOST_PP_VARIADICS_MSVC for clang
>> targeting VC++ allows that compiler to work with BoostPP ?
>>
>> 2) Are you saying that turning off BOOST_PP_VARIADICS_MSVC for clang
>> targeting VC++, allows that compiler to work with BoostPP when
>> -fno-ms-compatibility is defined ?
>>
>> 3) 2) Are you saying that turning off BOOST_PP_VARIADICS_MSVC for
>> clang targeting VC++, allows clang/C2 to work with BoostPP when
>> -fno-ms-compatibility is defined ?
>
> I'm telling you 3)2), yes, at least for this simple MPL program I tested.

I meant to write "3)" and not "3)2)" above. Sorry !

Try running all the Boost PP tests <g>. I would be very surprised if 
they worked in -fno-ms-compatibility mode. I will try it myself with 
clang targeting VC++ using clang-win.

>
> If I could get b2 to work with Clang/C2, I would have run the tests, but
> I'm not sure I can do that.

Touche ! I am not sure whether to use clang ( clang-linux ) or 
clang-win, but I am guessing the latter is the right match. Also I still 
don't know how to invoke clang/C2. I will look in the VS2015/VS2017 
directory structure unless you know what it is called and where it is ?

>
> I'm also telling you that since BOOST_PP_VARIADICS_MSVC=1 never works
> with any Clang, there is perhaps no reason to ever set it to 1
> regardless of what Clang it is and what options have been defined.

Well I can change config.hpp to reflect that. Ideally if clang targeting 
VC++ actually emulated the VC++ non-standard preprocessor perfectly 
BOOST_PP_VARIADICS_MSVC=1 would absolutely have to be defined in order 
for clang targeting VC++ to work properly with Boost PP. That is the 
obvious reason why it has been used in that situation.