Am Donnerstag, 19. Dezember 2013, 16:23:08 schrieb Jan Kundrát: > On Thursday, 19 December 2013 16:00:13 CEST, Ian Stakenvicius wrote: > > A change in profiles? 14.0/* adds that to the default CXXFLAGS in > > base, new stage3's etc are all rolled with this. We recommend > > migration to 14.0 profile and have a check somewhere about > > "-std=c++11" missing from CXXFLAGS in case it's overridden in > > make.conf, so users put it in place? > > Before you invest any more time in this, please understand that C++98 and > C++11 are source-incompatible. There is no way to expect that a package > builds fine when you throw -std=c++11 on it. And even if you patched them > all, you are breaking an unknown number of 3rd party software over which > you have exactly zero control.
No. If you do something against the standard that is working due to lack of control when compiling with -std=c++98, then your source code is severly broken. Most developers will use C++03 (plus tr1) anyway, won't they? And no, the languages are _not_ "source-incompatible". That would be a scandal! But if you have your C++98/03 code, and do what most developers do and let your console be flooded with warnings you ignore, you must not be surprised, if the compilation fails when you decide to throw "-std=c++11 -Wall -Wextra -Wpedantic -fsanitize=address -fsanitize=thread" with gcc 4.8.2 at it. There is absolutely no reason to expect a compilation to fail with C++11, if it went well with C++03 and "-Wall -Wextra -pedantic". If you try to outsmart your compiler, it will get it's revenge very soon and very hard. And according to [1] it goes even further: Quote: > If you use C++11 then in general you can combine C++11 code built with GCC > 4.X and C++03 code built with any GCC, but there is not the same guarantee > that you can combine with C++11 code built with GCC 4.Y or GCC 4.Z, because > the C++11 features are not all stable yet (e.g. for GCC 4.9 I'm about to add > a new virtual function to a base class in <future>.) This is why C++11 > support is still labelled "experimental", because it would be worse to claim > it's stable and then have to break the ABI. So basically C++11 <-> C++03 is no problem at all (unless you *export* certain symbols [2]), but combining C++11 from different gcc versions is nowhere guaranteed to work. Cheers Sven [1] : https://lwn.net/Articles/552831/ [2] : http://gcc.gnu.org/wiki/Cxx11AbiCompatibility
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