Re: [gentoo-dev] Re: RFC: c++14 global USE flag

[Anthony G. Basile]

On 04/28/15 17:52, Mike Gilbert wrote:
> On Tue, Apr 28, 2015 at 4:07 PM, Anthony G. Basile <blueness@g.o> wrote:
>> On 04/26/15 23:21, Duncan wrote:
>>> Diego Elio Pettenò posted on Sun, 26 Apr 2015 17:41:04 +0100 as excerpted:
>>>
>>>> On 25 April 2015 at 16:57, Duncan <1i5t5.duncan@×××.net> wrote:
>>>>
>>>>> Of course, one thing that could make the process faster would be if C++
>>>>> based packages were marked some way.
>>>>
>>>> revdep-rebuild --soname 'libstdc\+\+.so.*'
>>>>
>>>> should do the trick. Stuff that does not link the library (statically
>>>> linked or using libsupc++) should not really matter.
>>> Thanks.  Obvious in hindsight. =:^)
>>>
>> just saw this.  This works unless you have two versions of gcc installed.
>> The c++11 abi emitted by gcc-4.7 and 4.8 are different and since you link
>> against the latest version (see the ordering of directories in
>> /etc/ld.so.conf.d/05gcc-x86_64-pc-linux-gnu.conf), building with the earlier
>> gcc can cause breakage.  We may not want to support such a situation but I'd
>> like to.
> As I understand it, a given version of gcc links objects against its
> own version of libstdc++, but the "latest" version of libstdc++ is
> loaded by ld.so at runtime.
>
> Maybe that's what you meant, but I wanted to clarify that. And if I am
> wrong on that, please correct me. ^_^
>

Yes.  So you could, for example, fix this by setting the correct rpath 
at link time so the correct library gets loaded at runtime.

-- 
Anthony G. Basile, Ph.D.
Gentoo Linux Developer [Hardened]
E-Mail    : blueness@g.o
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