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[release] Release schedule changes..
by Rene Rivera 27 Jan '15

27 Jan '15

After some discussion in the Boost Release Team we've decided on an ongoing schedule for releases. Taking into account the realities of how long it takes for authors and the release team to work on a release we've decided to move to *three* releases a year. The targets for the releases will now be: * Spring release on the second Wednesday of April. * Summer release on the second Wednesday of August. * Fall/Winter release on the second Wednesday of December. There will be no January release. This will allow for the fact that most people are on extended holidays during Winter. It will also allow for people to work on larger changes that require more testing time during the longer Winter period. We are also moving to Wednesday release to allow the release managers non-weekend time to work before and after the release. Please consult the Boost calendar for specific dates and merge schedule for the next release. Thanks, the Boost Release Team. -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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Boost modular: Build without version number suffixes
by Robert Dailey 27 Jan '15

27 Jan '15

When I build modular boost on Linux Mint 17, I get SO files named like so: libboost_date_time.so.1.57.0 with a corresponding symlink without the version number: libboost_date_time.so I'd like it to build without the version number because when I rename the base file to remove the version, code links fine but during runtime it tries to load the SO with the version number at the end. I don't know how to fix that, so I assume the fix is to build boost without the version numbers. Any help is appreciated.

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[doc][build]
by Damian Vicino 27 Jan '15

27 Jan '15

Hi, I noticed the boost.build site links to documentations are broken in http://www.boost.org/doc/libs/1_57_0/tools/build/index.html <http://www.boost.org/doc/libs/1_57_0/tools/build/index.html>: http://www.boost.org/doc/libs/doc/html/bbv2.html <http://www.boost.org/doc/libs/doc/html/bbv2.html> http://www.boost.org/doc/libs/1_57_0/tools/build/doc/userman.pdf <http://www.boost.org/doc/libs/1_57_0/tools/build/doc/userman.pdf> both return 404. I got there following links in installation documentation.

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[endian] [bikeshed] Conversion function naming discussion
by Beman Dawes 26 Jan '15

26 Jan '15

Naming is always a bike shed issue. I'm starting a separate thread for those who don't care can easily ignore it. The current names I'm least comfortable with are the conversion function names in the endian sub-namespace: big_to_native big_to_native_inplace native_to_big native_to_big_inplace little_to_native little_to_native_inplace native_to_little native_to_little_inplace conditional_reverse conditional_reverse_inplace These are quite explicit, but are a bit too long and awkward for my taste. I'd be willing to change these names if someone can come up with replacements that are shorter and less awkward, but still reasonable explicit. --Beman

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Boost 1.58 schedule available?
by Barend Gehrels 26 Jan '15

26 Jan '15

Hi, Boost 1.57 was released last November 3, so it is probably about the time to merge to master again? Is there already a schedule available? Thanks, Barend

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RFC Expression Validity Asserts
by Matt Calabrese 26 Jan '15

26 Jan '15

I've found it useful, especially in tests, to easily be able to do expression validity checking via SFINAE in a static assert. In other words, it's frequently useful to want to quickly test to make sure that a particular expression does or does not compile, similar in some ways to a concepts-lite usage pattern. The general idea is that you want to static assert that, given a series of object declarations of a specific type, a specified expression or series of expressions that deal with those objects would or would not cause substitution to fail had the object types been dependent on a template parameter. It internally relies on a macro that is invoked as such: ////////// IS_VALID_EXPR( (int) a, (float) b, // etc.. (a + b) (a - b) // etc. ) ////////// The above macro invocation results in an expression that is a constexpr bool which is true iff substitution would not fail. With the above macro, one can do, for instance: static_assert(IS_VALID_EXPR((const int) a, ++a), "Some error message."); I've found this pattern so common that I've created a macro that takes such a series of declarations and expressions and automatically produces a simple static_assert, outputting the declarations and the expression that did not compile. A slimmed down version of this macro can be toyed with via the link below (this slim version allows only one declaration and one expression per macro): http://ideone.com/RHd6FM Briefly, using the macro as such: STATIC_ASSERT_VALID ( (const int) a, ++a ); is able to produce a very human-readable error message: prog.cpp:58:1: error: static assertion failed: ******************** Given: const int a; The following expression was expected to compile but did not: ++a ******************** There is a similar macro for verifying that an expression does not compile, which I find is much more useful in practice. Notable is that the validity macro is an expression -- no statement or other declarations are introduced -- and the static assert macro produces a single static_assert. This means that you can use the assertion macro in the normal scopes that any static_assert can be used (namespace scope, class scope, function scope...). One limitation is that because it uses lambdas behind the scenes, the context in which the validity macro may be used is slightly restricted (I.E. it can't be used in an un-evaluated context). Is this something people would generally find useful? If it is considered generally useful, I don't think it's really worthy of its own library, so where would it go? Years ago I probably would have just assumed utility, but I'm not really sure where it would go in the modern boost structure. The slim version can easily have no dependencies, though the more general solution ideally depends on Boost.Preprocessor. The macros themselves require C++14, though slightly less-useful forms (ones that introduce additional declarations) could be made that would work in C++11. -- -Matt Calabrese

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Templight Installation - watch your version of svn
by Fletcher, John P 26 Jan '15

26 Jan '15

I have just been installing Templight and have hit a problem. Templight installation involves installing Clang and then applying a patch to it. Older versions of svn (before 1.7) do not have the svn patch command which is used on the installation. Unfortunately Ubuntu 12.04 has version 1.6.17 installed and does not offer an update. The solution to this has been to upgrade svn to a later version from WANdisco (see http://www.wandisco.com/subversion/download) After the upgrade, the patch command will still not run if the downloads of LLVM and Clang were done with the old version of svn. So the best thing is to upgrade svn before starting. Of course I did not know this at the time. I am sending this to save someone else the same trouble. Best wishes John

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[Test][Thread] Regression since 9 December?
by Vicente J. Botet Escriba 26 Jan '15

26 Jan '15

Hi, I'm getting a regression on all the Boost.Thread tests using Boost.Test to fail after this commit https://github.com/boostorg/test/commit/1eaffb96ceec82882a4e947c99735a37271…. See http://www.boost.org/development/tests/develop/developer/output/Sandia-clan…. |../../../boost/system/config.hpp:34:3: erreur: #error Must not define both BOOST_SYSTEM_DYN_LINK and BOOST_SYSTEM_STATIC_LINK # error Must not define both BOOST_SYSTEM_DYN_LINK and BOOST_SYSTEM_STATIC_LINK | When I comment the added lines everything works correctly as before. The Boost.Thread jamfile contains | <library>/boost/test//boost_unit_test_framework/<link>static | If I change it to | <library>/boost/test//boost_unit_test_framework | I get an error |darwin.link ../../../bin.v2/libs/thread/test/test_thread.test/darwin-4.9.1/debug/threading-multi/test_thread Undefined symbols for architecture x86_64: "_main", referenced from: start in crt1.10.6.o ld: symbol(s) not found for architecture x86_64 collect2: erreur: ld a retourné 1 code d'état d'exécution "/usr/gcc-4.9.1/bin/g++-4.9.1" -o "../../../bin.v2/libs/thread/test/test_thread.test/darwin-4.9.1/debug/threading-multi/test_thread" "../../../bin.v2/libs/thread/test/test_thread.test/darwin-4.9.1/debug/threading-multi/test_thread.o" "../../../bin.v2/libs/thread/test/test_thread.test/darwin-4.9.1/debug/threading-multi/winrt_init.o" "../../../bin.v2/libs/test/build/darwin-4.9.1/debug/threading-multi/libboost_unit_test_framework.dylib" "../../../bin.v2/libs/timer/build/darwin-4.9.1/debug/threading-multi/libboost_timer.dylib" "../../../bin.v2/libs/chrono/build/darwin-4.9.1/debug/threading-multi/libboost_chrono.dylib" "../../../bin.v2/libs/thread/build/darwin-4.9.1/debug/threading-multi/libboost_thread.dylib" "../../../bin.v2/libs/system/build/darwin-4.9.1/debug/threading-multi/libboost_system.dylib" -g | Do others observe the same? Do you have an idea how this can be fixed? Best, Vicente

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Boost build failure on master
by Michael Caisse 25 Jan '15

25 Jan '15

I normally just compile and test Spirit/Fusion tests using the super project layout. That works fine; however, I'm setting up Bamboo build artifacts for all of Boost to enable slicker testing. As a result, I'm just trying to build all of Boost after a checkout. I admit that I've never found this to work properly. I'm following what I think are the standard instructions [1]: (lets keep it simple with linux for now) git clone --recursive git@github.com:boostorg/boost.git cd boost ./bootstrap.sh ./b2 headers ./b2 The result: error: Name clash for '<pstage/lib>libboost_system.so.1.58.0' error: error: Tried to build the target twice, with property sets having error: these incompabile properties: error: error: - none error: - <address-model>64 <architecture>x86 error: error: Please make sure to have consistent requirements for these error: properties everywhere in your project, especially for install error: targets. Ideas? Thanks! Michael 1. <https://svn.boost.org/trac/boost/wiki/TryModBoost#InstallingModularBoost> -- Michael Caisse ciere consulting ciere.com

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[thread] Timed waits in Boost.Thread potentially fundamentally broken on Windows (possibly rest of Boost too)
by Niall Douglas 25 Jan '15

25 Jan '15

Dear all, CC: Stephan @ Microsoft - Stephan I'd love to know what the MSVC STL does below so we have the option of matching your behaviour. During investigating this bug report for Boost.Thread (https://svn.boost.org/trac/boost/ticket/9856) I have discovered a very worrying situation: it would appear that potentially all timed waits in Boost.Thread, and potentially in other parts of Boost, are broken on Windows Vista and later and have been for some years. The problem is in correct handling of timeouts. If one does this: mutex mtx; condition_variable cond; unique_lock<mutex> lk(mtx); assert(cv_status::timeout == cond.wait_for(lk, chrono::seconds(1))); ... one would reasonably expect occasional failures on POSIX due to spurious wakeups. It turns out that this also spuriously fails on Windows, which is a surprise probably to many as Windows hides signal handling (actually APCs) inside its Win32 APIs and automatically restarts the operation after interruption. There is, therefore, the potential that quite a lot of code written to use Boost.Thread on Windows makes the hard assumption that the assert above will never fail. The reason why Windows spuriously fails above isn't due to spurious wakeups, it is in fact due to changes in the Vista kernel scheduler as documented at https://technet.microsoft.com/en-us/magazine/2007.02.vistakernel.aspx. In essence, if you now ask Windows to go sleep for X milliseconds, Windows Vista onwards will in fact sleep for anywhere between zero and X+N milliseconds where N is some arbitrarily long value. In other words, timeouts in Windows are purely advisory, and are freely ignored by the Windows kernel from Vista onwards. You can test this for yourself using this little program which reduces the #9856 bug report to its Win32 API essentials: #include <windows.h> #include <stdio.h> #include <chrono> int main(void) { ULONG ulDelay_ms = 20; HANDLE hSemaphoreDelay = CreateSemaphore(NULL, 0, 1, NULL); for (size_t n = 0; n < 50; n++) { while (1) { auto begin = std::chrono::high_resolution_clock::now(); ULONG hr = WaitForSingleObject(hSemaphoreDelay, ulDelay_ms); auto end = std::chrono::high_resolution_clock::now(); auto diff = end - begin; if (hr == WAIT_ABANDONED) printf("Wait Abandoned "); else if (hr == WAIT_TIMEOUT) printf("Timed out "); else printf("Signaled "); DWORD lTDelta = std::chrono::duration_cast<std::chrono::milliseconds>(diff).count(); printf("Target Wait Interval: %u Real Wait Interval: %u (%u)\n", ulDelay_ms, lTDelta, diff.count()); if (lTDelta >= ulDelay_ms) break; } printf("\n"); } CloseHandle(hSemaphoreDelay); return 0; } As you'll see, actual time waited is anywhere between zero and 20 + N milliseconds where actual time waited is sometimes a whole integer multiple of the Windows kernel granularity (15 ms) or some fraction of that granularity. Most of the time he tries to hit what you asked for, but you get no guarantees. More detail about how and why Windows Vista onwards does this can be found at http://forum.sysinternals.com/bug-in-waitable-timers_topic16229.html. This raises the question about what to do with Boost.Thread. We have the following options: Option 1: Timed waits are allowed to spuriously fail by the standard, so we mark this as wontfix and move on. Anyone using the predicate timed waits has never seen a problem here anyway. Option 2: We loop waiting until steady_clock (really QueryPerformanceCounter under Boost) shows the requested timeout has passed. Problem: This wastes battery power and generates needless wakeups. A more intelligent implementation would ask Windows for the thread quanta and transform timeouts to match the Vista kernel scheduler in combination with always using deadline scheduling, but this would slow down the timed waits implementation. Option 3: We adjust Boost.Thread to return timeouts when Windows returns a timed out status code, even if the actual time waited is considerably lower than the time requested. Problem: some code written for POSIX where when you ask for a timeout you always get it may misbehave in this situation. Boost commmunity, I turn it over to you for advice! Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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