On Thu, Mar 24, 2016 at 8:10 AM, Jonathan Wakely <jwakely.gcc@xxxxxxxxx> wrote: > On 24 March 2016 at 11:55, Jeffrey Walton wrote: >> In the test program below, why does -Wabi-tag trigger a warning with >> the std::string when using -std=c++03? > > "Although the changes were made for C++11 conformance, the choice of > ABI to use is independent of the -std option used to compile your > code, i.e. for a given GCC build the default value of the > _GLIBCXX_USE_CXX11_ABI macro is the same for all dialects. This > ensures that the -std does not change the ABI, so that it is > straightforward to link C++03 and C++11 code together. " > > https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html Thanks. I recall reading that a couple of days ago. I still don't quite understand what it means. I'm obviously missing something. I guess my knowledge gap is due to _GLIBCXX_USE_CXX11_ABI should apply to C++11 and above to comply with the newer C++ rules, wrote-on-copy strings, etc. I don't understand how it effects C++03 and below since the rules that required the change don't apply. Jeff
