On 27 October 2016 at 15:30, Edward Diener <eldlistmailingz@xxxxxxxxxxxxxx> wrote: > On 10/27/2016 10:00 AM, Jonathan Wakely wrote: >> >> On 27 October 2016 at 14:52, Edward Diener wrote: >>> >>> It sounds like you are also saying that there is no way to catch the old >>> type, even if I wanted to, since the header file declaration has the >>> decorated attribute. >> >> >> No, the attribute is only present conditionally, see >> https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html >> >> If you compile with _GLIBCXX_USE_CXX11_ABI defined to zero then you >> get the declaration of the old type (and the old COW std::string, and >> the old std::list with O(n) size()). >> > > Thanks ! IMO clearly you should be throwing the std::ios_base::failure which > corresponds to the _GLIBCXX_USE_CXX11_ABI macro setting being used. The exception is thrown from code inside libstdc++.so, which is already compiled and can't be affected by a macro defined when you #include <iostream>. We could maybe set a thread-local variable every time an iostream operation is performed, based on the macro value, and have the library inspect the thread-local to decide which type to throw, but that would be ugly, and still not always do the right thing. > That gcc > is throwing the the old type even when _GLIBCXX_USE_CXX11_ABI is defined as > 1 cannot be right. But I think that is what you already said. No, I said I'm going to change it to always throw the new type. It will won't depend on the macro. > What always works now is to catch std::exception rather than > std::ios_base::failure so I will use that. >
