On Mon, 29 Jun 2015 08:18:12 +0200 Murray Cumming <murr...@murrayc.com> wrote: > On Sun, 2015-06-28 at 20:30 +0100, Chris Vine wrote: > > On Sun, 28 Jun 2015 20:17:28 +0200 > > Murray Cumming <murr...@murrayc.com> wrote: > > > Given that --std=c+11 breaks ABI compatibility (at least in the > > > standard library), I wonder if/when distros would ever build > > > glibmm with C++11 support. > > > > gcc-3.4 and gcc-4.* do not provide libstdc++ with a C++11 compliant > > ABI (this is mainly concerned with gcc's copy on write string > > implementation) and gcc-5.1 does by default do so, > [snip] > > So do you think any apps have been built with C++11 on mainstream > distros so far?
Yes, if only because mozilla now requires c++11. I occasionally see other things I compile which test for C++11, although don't ask me what they were. However, far more will link with C++11 code dynamically without knowing it. I noticed that llvm-3.6 now uses C++11 (I filed a bug when mesa-10.4 failed to compile with llvm-3.6 because llvm-3.6 switched to std::unique_ptr - mesa 10.5 now does compile with llvm-3.6). Some form of C++11 support has been available in gcc for ages - gcc-4.4 for example provided some support (smart pointers, variadic templates, move semantics, the additional wide character types and some of C++11 threads). gcc-4.5 supported lambdas and most of C++11 threads (but not the memory model). gcc-4.6 supported range-for and an improved template implementation. gcc-4.7 was nearly C++11 complete (including template aliasing) except that it did not support the full C++11 memory model nor regular expressions and some of its tuple implementation was not fully conforming. gcc-4.8 seems to be pretty much completely conforming (including the C++ memory model) except for regular expressions. gcc-4.9 I think is pretty well c++11 complete (including regular expressions) except for the string implementation which needed ABI breakage to fix, and a few other things in the standard library (including a O(1) std::list::size() function - see https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html). To see what mozilla requires by way of gcc see https://developer.mozilla.org/en-US/docs/Using_CXX_in_Mozilla_code (latest releases require gcc-4.7). The thing to do is to decide what the earliest version of gcc you want gtkmm to compile with and test with that (and with gcc-5). I would suggest possibly gcc-4.6 or gcc-4.7. The other point about the -std=c++0x, -std=c++11 and -std=c++14 flags is that they do not change the ABI from the gcc-3.4 ABI to the gcc-5.1 ABI. Only defining _GLIBCXX_USE_CXX11_ABI does that. Instead the flags make some additional API available (or not available) and make some minor other changes to the API. Code compiled with the -std=c++11 flag can link quite happily with a C++98/03 library such as gtkmm, provided the same libstdc++ ABI is used for both. The best way a distribution can do that is to recompile all its C++ libraries with the same _GLIBCXX_USE_CXX11_ABI setting and make that the default for the compilation of user programs. You might also want to read this, for an explanation about how Fedora is dealing with gcc-5: http://developerblog.redhat.com/2015/02/10/gcc-5-in-fedora/ Chris _______________________________________________ gtkmm-list mailing list gtkmm-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtkmm-list
