On Mon, 2017-02-06 at 03:17 +0700, [email protected] wrote: > Hello *, > > Sorry, I'm not a C++ expert, and I need some help. I'm trying to > bump > sci-mathematics/ginac and some of its revdeps. The current ginac is > 1.7.2, > and it needs -std=c++11 (or gnu++11). I added append-cxxflags > -std=c++11 > to src_configure; also added src_test which was missing previously. > ginac > compiles and passes tests, also ginsh works. Fine. > > The current sci-physics/nestedsums is 1.5.1, it depends on > > =sci-mathematics/ginac-1.7 and needs -std=c++11. I've made the > > necessary > > changes to the ebuild, it compiles and seems to work (its testsuite > is > broken, cannot use it). Also fine. > > Then there's sci-physics/reduze. It is still 2.1, no new versions > have > appeared. It has to be recompiles after upgrading ginac. > > If I compile it without -std=c++11, I get a lot of syntax errors in > .h > files from ginac: > > /usr/include/ginac/ptr.h:37:13: error: expected ‘;’ at end of member > declaration > /usr/include/ginac/ptr.h:37:15: error: ‘noexcept’ does not name a > type > /usr/include/ginac/ptr.h:57:31: error: ‘>>’ should be ‘> >’ within a > nested template argument list > /usr/include/ginac/ptr.h:124:44: error: expected initializer before > ‘noexcept’ > > etc. etc. > > If I compile it with -std=c++11, I get errors about operators from > stdlib: > > /var/tmp/portage/sci-physics/reduze-2.1/work/reduze- > 2.1/reduze/files.cpp:726:27: > error: no match for ‘operator<<’ (operand types are > ‘std::basic_ostream<char>’ and ‘std::ofstream {aka > std::basic_ofstream<char>}’) > /var/tmp/portage/sci-physics/reduze-2.1/work/reduze- > 2.1/reduze/functions.h:258:46: > error: cannot bind ‘std::basic_ostream<char>’ lvalue to > ‘std::basic_ostream<char>&&’ > > etc. > > Does this mean that in order to compile it stdlib should be > recompiled > with -std=c++11? Will it break all the other C++ packages in the > system? > > Many thanks in advance, > Andrey
Dear Andrey, GCC C++ versions are in general ABI compatible, i.e. linking a package built against -std=c++98 will generally link against a package built with -std=c++11, unless you do some __cplusplus macro black magic. The error you're saying is caused by crappy code, mainly stuff such as std::cout << std::cout for instance, which is broken, wrong and overall meaningless. In C++98 this used to compile, as the void* conversion operator was implicitly called, printing the address of the std::cout global object. This conversion operator has been removed in C++11 in favour of the save bool idiom, and hence this code won't compile anymore. So: 1) You will likely require C++11 2) and you will need to fix the crappy code in sci-physics/reduze if you're on IRC, we can discuss this a bit, I don't want to litter the mailing list with tips on how to make code C++11 ready. If I have time next week I could maybe look at it. Regards David
