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List:       gentoo-dev
Subject:    Re: [gentoo-dev] Re: RFC: News item regarding c++98 vs c++11
From:       "Anthony G. Basile" <basile () opensource ! dyc ! edu>
Date:       2014-10-26 11:19:46
Message-ID: 544CD8D2.5030801 () opensource ! dyc ! edu
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On 10/25/14 05:32, "Paweł Hajdan, Jr." wrote:
> On 10/24/14 7:29 PM, Anthony G. Basile wrote:
>> So I don't have to keep email the entire item to the list, how about
>> just adding it as follows:
>>
>> "Nor is c++11 code compiled with gcc-4.7 ABI-compatible with c++11
>> compiled with 4.8, and vice versa.  An example can be see in ref.
>> [2]"
>>
>> Ref. [2] https://bugs.gentoo.org/show_bug.cgi?id=513386
>
> I think this could still be clearer about the user/sysadmin perspective
> more than a developer perspective, i.e. present this more like "both
> gcc-4.7 and 4.8 installed with 4.7 being active" than "not
> ABI-compatible with C++11 compiled with 4.8".
>
> Here's my suggested draft:
>
> -----%<----- CUT HERE -----%<-----
> GCC 4.7 introduced the new experimental 2011 ISO C++ standard [1].
>
> Users that wish to try enabling C++11 globally (e.g. using CXXFLAGS)
> should exercise caution because it is not ABI-compatible with C++98.
> Packages which are self-contained or do not link against any libraries
> written in C++ are not affected. Note that some packages like
> www-client/chromium and net-libs/webkit-gtk among others are already
> using C++11 features.
>
> Even having different versions of gcc installed simultaneously might
> lead to problems, especially if the active version of gcc is older.
> Please see [2] for example known bug with webkit-gtk. It is recommended
> to set the latest installed version of gcc as active; some packages may
> work when an older version is selected, but GCC upstream provides no
> guarantees of C++11 ABI stability for code compiled with gcc-4.x and 4.y
> for any x != y [3].
>
> Ref.
> [1] http://www.stroustrup.com/C++11FAQ.html
> [2] https://bugs.gentoo.org/show_bug.cgi?id=513386
> [3] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61758
> -----%<----- CUT HERE -----%<-----
>
> Paweł
>

I incorporated these points, but did not replace my original language. 
Both perspectives are now in there.

-- 
Anthony G. Basile, Ph. D.
Chair of Information Technology
D'Youville College
Buffalo, NY 14201
(716) 829-8197

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