[gentoo-science] -std=c++11

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