From the discussion about abi compatibility when the Boost.System library is compiled e.g. in c++03 mode and then included in ac++11 project or vice versa (https://groups.google.com/forum/#!topic/boost-developers-archive/EWG5NVOZo_ g)
When can we drop C++03 support? :D
This will probably be ignored or shouted down, but maybe someone just needs to make a concrete suggestion about which people can discuss and vote so I'm giving it a shot: What about the first or second release in 2020 ? By then, all major toolchains have had solid c++11 support for at least 5 years ( I think, msvc was the last one with VS2015) and at least partial support for 7+ years (gcc 4.8, msvc 2013, clang 3.3). Also, most likely c++20 will be released in that year, which means that c++03 compatible libraries would have to support 5 different (and partial incompatible) language versions by then (not to mention ABI-compatibility considerations between different versions). That should also be enough time to ensure that the last c++03 release (late 2019) is really solid (for projects that still can't upgrade to c++11) and ideally there could be a few more bugfix-releases afterwards as is often done by other software projects. And before someone starts to raise straw mans: That of course wouldn't mean that a particular library *must* no longer compile in 03 mode, but one can no longer rely on the boost-internal dependencies remaining c++03 compatible. Best Mike