Re: [gentoo-dev] impending c++11 clusterfuck?

[Anthony G. Basile]

On 12/1/15 6:25 AM, Michał Górny wrote:
>
> Dnia 30 listopada 2015 12:17:32 CET, "Anthony G. Basile" <blueness@g.o> napisał(a):
>>
>> different direction: what about building with
>> rpath=/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.3/ and then making sure that
>> portage respects that library file during any --depclean or
>> @preserved-rebuild?  i'm not sure how we'd
>> inject|||LDFLAGS=-Wl,-rpath=... consistantly and sanely into all c++
>> builds.
>>
>> this would solve all problems i can see: 1) gcc-config reshuffles
>> /etc/ld.so.conf.d/05gcc-<tuple>.conf but rpath takes presidence, 2) the
>> correct library symbols are guaranteed to be there in both exe and lib.
>>
>> 3) it pro-actively guards against abi mismatches when switching gcc
>> even
>> for other languages like fortran, java, obj-c.|
> I'm afraid any of those problems are really affecting us here. GCC maintains backwards ABI compatibility in the library, so applications will continue to work as long as runtime libstdc++ isn't older than build time.
>
> Currently, we always force newest installed libstdc++ at runtime, and use the version matching GCC version at build time, so that works.
>
> So the best thing your solution could give us is loading the wrong version of libstdc++ when you link to a library built against older one.
Yeah there are two problems going on here and the libsigc++-2.6 is the
c++98 <=> 11 problem.  So on that bug we're talking about selectively
adding -std=c++11 (or possibly gnu++11) to packages.  This may get
messy.  I'm wondering if it isn't possible to just globally add
CXXFLAGS+="-std=c++11".  This should work because anything written with
c++98 will compile under c++11 (although not vice versa) although I
don't know how we'd migrate existing systems.

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