Hello, Answering to myself after digging through libstdc++ includes and sources:
2013-11-16 15:05, Eugene V. Lyubimkin: > For some reason, on armel architecture exclusively [1], g++ has problems > compiling seemingly any program which uses std::future [2]. std::future is actually defined in libstdc++'s headers only if: "#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) && (ATOMIC_INT_LOCK_FREE > 1)" On armel porterbox, ATOMIC_INT_LOCK_FREE == 1, which according to the libstdc++ documentation means that, unlike every other Debian architecture, operations on atomic ints are not guaranteed to be lock-free there. I don't know is this a shortcoming in libstdc++ configuration/implementation or armel doesn't provide atomic incrementing/decrementing facilities. As for atomics, std::future itself only uses std::atomic_flag, which is guaranteed to lock-free by C++ standard. But another type it uses, std::exception_ptr, requires atomic ints, namely, it uses a typedef _Atomic_word for reference counting (incrementing and decrementing using the acquire/release memory model). Either way, right now any C++11 program linked to libstdc++ which uses <future> facilities or transfer exceptions will fail to compile on armel. On armhf there is no such a problem. -- Eugene V. Lyubimkin aka JackYF, JID: jackyf.devel(maildog)gmail.com C++ GNU/Linux userspace developer, Debian Developer -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
