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[Operators] Update, const-correctness and operator chaining
by Andrew Ho 02 Jul '13

02 Jul '13

Hi, I was doing some testing with Daniel Frey/Marc Glisse's proposed 4- overload set for binary operators. For reference, here's the overload set applied to commutative addition: friend T operator +( const T& lhs, const T& rhs) { T nrv(lhs); nrv += rhs; return nrv; } friend T operator +(T&& lhs, const T& rhs) { return std::move(lhs += rhs); } friend T operator +(const T& lhs, T&& rhs) { T nrv(lhs); nrv += boost::move(rhs); return nrv; } friend T operator +(T&& lhs, T&& rhs) { return boost::move(lhs += boost::move(rhs)); } This allows this to be done: val1 + val2 = val3; changing the return type to const T would allow the compiler to catch this, but now doing val1 + val2 + val3 must always use copy semantics instead of move semantics. I can't think of a way which would fix this issue without breaking the use of move semantics. How should we proceed with this? It's obviously bad usage, but the compiler should be able to catch this since it's easy to mistype + as =. Interestingly enough, doing testing with std::string shows the same "problem": std::string str1("hello"), str2(" "), str3("world"); str1 + str2 = str3; I tested this issue with std::string and found it in vs2012, gcc 4.3.2, and mingw/gcc 4.8.0. I don't have access to a compiler which pre-dates C++0x/C++11 so I don't know if this issue has always been present. Compiling with gcc 4.8.0 with - std=c++03 still has the issue.

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Any interest in bitstream class?
by Paul Long 02 Jul '13

02 Jul '13

Same semantics as, e.g., stringstream, but it operates on binary data. I already have the analogues to istringstream/stringbuf (you can take a look at ibitstream/bitbuf at https://github.com/dplong/bstream) There are some interesting features, but I won't go into them here. If there is interest, I would implement obitstream and bitstream and possibly support Boost::dynamic_bitset. The rationale is _succinct_ expression of predictive parsing of binary data. I've used ibitstream in production code for decoding RTP headers and frames of various video encodings. Below is a simple function that decodes an RTP header using ibitstream; I also have a GitHub repo that contains more complex code for high-level parsing of H.264 frames at https://github.com/dplong/rtspudph264 struct RtpHeader { bool padding, marker; bitset<7> payloadType; WORD sequenceNumber; DWORD timestamp, ssrcIdentifier; vector<DWORD> csrcIdentifier; struct { bool present; WORD identifier; vector<BYTE> contents; } extension; }; bool ParseRtpHeader(const BYTE *buffer, RtpHeader &rtp) { ibitstream bin(buffer); static const bitset<2> version(0x2); bitset<4> csrcCount; WORD extensionLength; bin >> version >> rtp.padding >> rtp.extension.present >> csrcCount >> rtp.marker >> rtp.payloadType >> rtp.sequenceNumber >> rtp.timestamp >> rtp.ssrcIdentifier >> setrepeat(csrcCount.to_ulong()) >> rtp.csrcIdentifier; if (rtp.extension.present) { bin >> rtp.extension.identifier >> extensionLength >> setrepeat(extensionLength * sizeof(DWORD)) >> rtp.extension.contents; } return bin.good(); }

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Static initialization of boost shared objects question
by Juan Carlos Franzoy 02 Jul '13

02 Jul '13

Hello. Thanks for reading my question. I fell into a deadlock in static initialization of boost shared objects. The deadlock occurs in a reentrant call to a function which contains a definition of a static variable. Apparenlty gcc protects the initialization of such variables with a condition variable. Looking at the c++ code nothing at all make anybody suspect about reentrancy. My "interpretation of the fact" may be titled 'something in gcc, ld, ld.so, c++language made the call to be reentrant' - There is a function boost::system::generic_category() that has a static variable V - V type is boost::system::annonymous-namespace::generic_error_category - boost::system::annonymous-namespace::generic_error_category is subclass of boost::system::error_category. - boost::system::annonymous-namespace::generic_error_category has no declared/defined constructor as well as all its superclasses - The compilation process generate the constructor boost::system::error_category::error_category() as a weak symbol inside every shared object that uses it. - There is a static variable boost::system::posix_category in one of the shared objects that is initialized calling boost::system::generic_category(). - when the static initialization of a shared object boost::system::posix_category get initialized - which calls boost::system::generic_category() - Inside boost::system::generic_category() starts the initialization of V which calls boost::system::error_category::error_category() - It may happend that the runtime calls an instance of boost::system::error_category::error_category() that resides in a shared object that is still not loaded - So that .so get loaded and it is called its own static initialization - which can call boost::system::generic_category() - BOOM I would love if you can confirm of refute my humble "interpretation". Details follows ------------------- boost version: 1-52-0 Operating system: uname -a SunOS bcpp-solaris10 5.10 Generic_147441-25 i86pc i386 i86pc $ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/export/home/local/gcc-4.6.2/libexec/gcc/i386-pc-solaris2.10/4.6.2/lto-wrapper Target: i386-pc-solaris2.10 Configured with: ../src/gcc-4.6.2/configure --prefix=/export/home/local/gcc-4.6.2 --with-gmp=/export/home/local/gcc-4.6.2/gmp-4.3.2 --with-mpfr=/export/home/local/gcc-4.6.2/mpfr-3.0.0 --with-mpc=/export/home/local/gcc-4.6.2/mpc-0.8.2 --with-libelf=/export/home/local/gcc-4.6.2/libelf-0.8.12 --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --enable-languages=c,c++ --with-as=/usr/local/bin/as --with-gnu-as --with-ld=/usr/ccs/bin/ld --without-gnu-ld --enable-plugin --enable-multilib --enable-version-specific-runtime-libs --enable-bootstrap --enable-ssp --enable-libssp --with-included-gettext --enable-lto --host=i386-pc-solaris2.10 --build=i386-pc-solaris2.10 Thread model: posix gcc version 4.6.2 (GCC) Callstack backtrace (lines begining with = are my comments): = = deadlock here: the threads is waiting itself = #0 0xfd459019 in __lwp_park () from /lib/libc.so.1 #1 0xfd45365e in cond_sleep_queue () from /lib/libc.so.1 #2 0xfd453817 in cond_wait_queue () from /lib/libc.so.1 #3 0xfd453b94 in cond_wait_common () from /lib/libc.so.1 #4 0xfd453d02 in _cond_wait () from /lib/libc.so.1 #5 0xfd453d2d in cond_wait () from /lib/libc.so.1 #6 0xfd453d66 in pthread_cond_wait () from /lib/libc.so.1 #7 0xfd632898 in __gthread_cond_wait (g=0xfd822ea8) at ...build-gcc/out/i386-pc-solaris2.10/libstdc++-v3/include/i386-pc-solaris2.10/bits/gthr-default.h:846 #8 __gthread_cond_wait_recursive (g=0xfd822ea8) at ...work/build-gcc/out/i386-pc-solaris2.10/libstdc++-v3/include/i386-pc-solaris2.10/bits/gthr-default.h:860 #9 __gnu_cxx::__cond::wait_recursive (g=0xfd822ea8) at ...build-gcc/out/i386-pc-solaris2.10/libstdc++-v3/include/ext/concurrence.h:377 #10 __cxa_guard_acquire (g=0xfd822ea8) at .../src/gcc-4.6.2/libstdc++-v3/libsupc++/guard.cc:289 = = Reentrant call to boost::system::generic_category() = #11 0xfd812313 in boost::system::generic_category () at libs/system/src/error_code.cpp:425 #12 0xfe85cd38 in __static_initialization_and_destruction_0(__initialize_p=1, __priority=65535) at ./boost/system/error_code.hpp:214 #13 0xfe85d05f in _GLOBAL__sub_I_instantiate_re2c_lexer_str.cpp () at libs/wave/src/instantiate_re2c_lexer_str.cpp:56 = = static initization of boost.wave library = #14 0xfe8868fd in __do_global_ctors_aux () from ...boost/lib/libboost_wave-gcc46-mt-d-32-SOLARIS-X86-1_52.so.1.52.0 #15 0xfe88692a in _init () from ...boost/lib/libboost_wave-gcc46-mt-d-32-SOLARIS-X86-1_52.so.1.52.0 #16 0xfefce37e in call_init () from /usr/lib/ld.so.1 #17 0xfefce1cf in is_dep_init () from /usr/lib/ld.so.1 #18 0xfefdaa4b in elf_bndr () from /usr/lib/ld.so.1 #19 0xfefc2ab4 in elf_rtbndr () from /usr/lib/ld.so.1 #20 0xfee60688 in ?? () #21 0xfee0c8f6 in boost::exception_detail::get_static_exception_object<boost::exception_detail::bad_alloc_>() at ./boost/exception/detail/exception_ptr.hpp:119 #22 0xfee0c0d2 in __static_initialization_and_destruction_0(__initialize_p=1, __priority=65535) at ./boost/exception/detail/exception_ptr.hpp:138 #23 0xfee0c271 in _GLOBAL__sub_I_future.cpp () at libs/thread/src/future.cpp:60 = = static initization of boost.thread library = #24 0xfee0d98d in __do_global_ctors_aux () from ...boost/lib/libboost_thread-gcc46-mt-d-32-SOLARIS-X86-1_52.so.1.52.0 #25 0xfee0d9ba in _init () from ...boost/lib/libboost_thread-gcc46-mt-d-32-SOLARIS-X86-1_52.so.1.52.0 #26 0xfefce37e in call_init () from /usr/lib/ld.so.1 #27 0xfefce1cf in is_dep_init () from /usr/lib/ld.so.1 #28 0xfefdaa4b in elf_bndr () from /usr/lib/ld.so.1 #29 0xfefc2ab4 in elf_rtbndr () from /usr/lib/ld.so.1 #30 0xfdce0688 in ?? () = = First calll to boost::system::generic_category() = #31 0xfd81232a in boost::system::generic_category () at libs/system/src/error_code.cpp:425 #32 0xfd812386 in __static_initialization_and_destruction_0(__initialize_p=1, __priority=65535) at ./boost/system/error_code.hpp:214 #33 0xfd8123ed in _GLOBAL__sub_I_error_code.cpp () at libs/system/src/error_code.cpp:430 = = static initialization of boost.system = #34 0xfd8126ed in __do_global_ctors_aux () from ...boost/lib/libboost_system-gcc46-mt-d-32-SOLARIS-X86-1_52.so.1.52.0 #35 0xfd81271a in _init () from ...boost/lib/libboost_system-gcc46-mt-d-32-SOLARIS-X86-1_52.so.1.52.0 #36 0xfefce37e in call_init () from /usr/lib/ld.so.1 #37 0xfefcd7d5 in setup () from /usr/lib/ld.so.1 #38 0xfefdba3e in _setup () from /usr/lib/ld.so.1 #39 0xfefc299c in _rt_boot () from /usr/lib/ld.so.1 #40 0x08047540 in ?? () #41 0x08047670 in ?? () More thanks for reading all.

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zlib not building (fedora x86_64)
by Neal Becker 02 Jul '13

02 Jul '13

I noticed zlib are not being built. I don't know why. rpm -qa zlib* zlib-1.2.7-9.fc18.i686 zlib-1.2.7-9.fc18.x86_64 zlib-devel-1.2.7-9.fc18.x86_64 bjam cxxflags=-march=native -sHAVE_ICU=1 -sEXPAT_INCLUDE=/usr - sEXPAT_LIBPATH=/usr/lib64 --layout=tagged threading=single,multi link=shared stage warning: No toolsets are configured. warning: Configuring default toolset "gcc". warning: If the default is wrong, your build may not work correctly. warning: Use the "toolset=xxxxx" option to override our guess. warning: For more configuration options, please consult warning: http://boost.org/boost-build2/doc/html/bbv2/advanced/configuration.html Performing configuration checks - 32-bit : no - 64-bit : yes - arm : no - mips1 : no - power : no - sparc : no - x86 : yes error: No best alternative for libs/coroutine/build/allocator_sources next alternative: required properties: <link>static <target-os>windows <threading>multi not matched next alternative: required properties: <link>static <segmented-stacks>on <threading>multi not matched next alternative: required properties: <link>static <threading>multi not matched - has_icu builds : yes warning: Graph library does not contain MPI-based parallel components. note: to enable them, add "using mpi ;" to your user-config.jam - zlib : no - iconv (libc) : yes - icu : yes - compiler-supports-ssse3 : yes - compiler-supports-avx2 : yes - gcc visibility : yes - long double support : yes warning: skipping optional Message Passing Interface (MPI) library. note: to enable MPI support, add "using mpi ;" to user-config.jam. note: to suppress this message, pass "--without-mpi" to bjam. note: otherwise, you can safely ignore this message. error: No best alternative for libs/coroutine/build/allocator_sources next alternative: required properties: <link>static <target-os>windows <threading>multi not matched next alternative: required properties: <link>static <segmented-stacks>on <threading>multi not matched next alternative: required properties: <link>static <threading>multi not matched - zlib : no (cached) Component configuration: - atomic : building - chrono : building - context : building - coroutine : building - date_time : building - exception : building - filesystem : building - graph : building - graph_parallel : building - iostreams : building - locale : building - log : building - math : building - mpi : building - program_options : building - python : building - random : building - regex : building - serialization : building - signals : building - system : building - test : building - thread : building - timer : building - wave : building

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boost 1.54.0 support for VS2013
by Charles_J_Wilson＠Dell.com 01 Jul '13

01 Jul '13

Has visualc.hpp been updated to support VC++12? (this was released in Visual Studio 2013 preview). I get the following issue with 1.54.0 beta built with VC++11 when compiling using VC++12: Error 1 error C2039: 'assert_not_arg' : is not a member of 'boost::mpl' (..\..\..\Logging\source\Core.cpp) C:\Users\Charles_J_Wilson\Documents\Projects\external\open_source\boost\1.54.0\boost_1_54_0\boost\iterator\detail\facade_iterator_category.hpp 166 Which is: # if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300) BOOST_MPL_ASSERT_NOT((is_iterator_category<Traversal>)); # endif The beta doesn't recognize the compiler version and suggests running the config tests. Where are the instructions for that? Charles Wilson Principal Software Development Engineer Dell | Enterprise Solutions Group

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[range] Time to merge Oven-to-Boost Extensions?
by Michel Morin 30 Jun '13

30 Jun '13

Hi, IIRC, the formal review is not necessary for the merge of Akira's Oven-to-Boost Extensions; only the range authors' review/permission are necessary. Neil, Nate, could we merge the extensions in the near future? I think everyone wants * `dropped` adaptor * `elements` adaptor * `taken` adaptor * `regular` utility so merging these first (and eventually merging the rest) would make the users happy. Regards, Michel

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Re: [boost] Any interest in bitstream class?
by Brian Wood 30 Jun '13

30 Jun '13

From: Rob Stewart > On Jun 28, 2013, at 6:50 PM, Paul Long <plong(a)packetizer.com> wrote: > >> Correct, but it is important to note that integrals are always encoded big endian in the bitstream. I >>suppose it's possible that someone would want some other endian, but that's got to be an obscure use >>case. > > There are plenty of little endian only contexts that would want to avoid the host->network->host > conversions for all transfers. The C++ Middleware Writer uses a "receiver makes right" approach to support that. There's a SameFormat class here: http://webEbenezer.net/misc/Formatting.hh that's used when both sides have the same endian-ness. -- Brian Ebenezer Enterprises - Was Eisenhower the last decent US President? http://webEbenezer.net

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Re: [boost] [Boost-users] Herb Sutter on C++ Standardization and Visual Studio
by Nathan Ridge 30 Jun '13

30 Jun '13

> Herb Sutter on C++ Standardization at Microsoft. > > http://channel9.msdn.com/Events/Build/2013/2-306 > > SGL Pretty good news, IMO. In addition to the C++11 and C++14 plans, Herb announced that Microsoft would complete the holes in their C++98 standard support by finally fixing their preprocessor and implementing correct two-phase name lookup (39:18 in the video). Perhaps the last discussion about these things [1] helped to tip the scale. In any case, I'm glad to hear it. Regards, Nate [1] http://boost.2283326.n4.nabble.com/C-announcements-coming-tomorrow-td463790…

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boost::thread dependency on boost::chrono (windows implementation)
by Christian Hägele 28 Jun '13

28 Jun '13

Hello, as boost::thread now depends on boost::chrono I have the following questions: In boost::chrono on windows the the steady_clock is implemented via QueryPerformanceCounter. This may lead to wrong results because on some systems QueryPerformanceCounter gives different results on different processors. In our software we encountered theses problems regularly on some customers machines and thus stopped using QueryPerformanceCounter without additional checking. The problem I'm talking about is described as a TODO in boost/chrono/system_clocks.hpp My questions is if functions like boost::thread::timed_join or boost::mutex::timed_wait may have similar problems on hardware where QueryPerformanceCounter gives wrong result. Is there a way (like a preprocessor macro) to have boost::thread use the old implementation independent from boost::chrono? Regards, Christian

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[1.54.0] Release candidates available
by Marshall Clow 28 Jun '13

28 Jun '13

Release candidate files for 1.54.0 are available at http://boost.cowic.de/rc/ As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. The files (and associated md5s) are: efbfbff5a85a9330951f243d0a46e4b9 *boost_1_54_0_rc1.tar.gz 15cb8c0803064faef0c4ddf5bc5ca279 *boost_1_54_0_rc1.tar.bz2 78a35834c45220a6164310e280abe675 *boost_1_54_0_rc1.zip 89e734ffd2afe0982b2d9fc21d033dba *boost_1_54_0_rc1.7z Thanks! -- The release managers

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