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[git workflow questions for boost]
by Robert Ramey 25 Jun '14

25 Jun '14

I've discovered a couple of changes I want to see incorporated into some boost libraries. In this particular instance the modules are mpl and tools. The "best" way of doing this for me is to: use github to fork the modules in question clone the modules to my local machine make (and test) my changes push them to the the fork enter a pull request. sometime later delete the fork from github This is well described here https://help.github.com/articles/fork-a-repo So far so good. But I have a couple of questions about this. I currently have modular boost installed on my machine. It seems that I want to: delete the module in question. clone to the same spot I just deleted. do everything above. delete the module again. clone from the original? update super project? rerun b2 headers? what? - I'm sort of at a loss here. I'm sort of uncomfortable with deleting the "official" version - but it seems the right think to do. I would appreciate any observations/advice from some more experienced boosters. Robert Ramey -- View this message in context: http://boost.2283326.n4.nabble.com/git-workflow-questions-for-boost-tp46644… Sent from the Boost - Dev mailing list archive at Nabble.com.

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new Boost.Test in 1.56.0?
by Yanchenko Maxim 25 Jun '14

25 Jun '14

Hi, There were many changes in Boost.Test recently. Will they go to the 1.56.0 release? Thanks, Maxim

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Attempting to Compile on AIX 6.1 with gcc
by Axel Ismirlian 24 Jun '14

24 Jun '14

Hello everyone, I have been attempting to compile the entirety of boost on AIX 6.1 with gcc. Currently, I am compiling for 32-bits. I have had some moderate success by specifying extra flags to the compilation, but some issues persist that may require code change (or simply more explicit linking) and as a result I am at loss of what to do. Here are some of the issues that pop up: ld: 0711-317 ERROR: Undefined symbol: .test_main(int, char**) collect2: error: ld returned 8 exit status ld: 0711-317 ERROR: Undefined symbol: init_unit_test_suite(int, char**) collect2: error: ld returned 8 exit status I think these two are linking issues, but I am not sure how to include the missing files. The first primarily affects boost.asio, but others are affected as well. The second primarily affects boost.conversion. gcc.link ../bin.v2/libs/math/test/test_bessel_k.test/gcc-4.8.1/debug/link-static/test_bessel_k collect2: fatal error: ../bin.v2/libs/math/test/test_instances/gcc-4.8.1/debug/link-static/libtest_instances.a: not a COFF file In the math library I get this issue, and also many floating point constants are being truncated to zero. Is there any way to prevent that? Allocator = std::allocator<long unsigned int>] BOOST_MP_FORCEINLINE BOOST_CONSTEXPR cpp_int_backend() BOOST_NOEXCEPT{} ../boost/multiprecision/cpp_int.hpp:1032:41: note: candidate expects 0 arguments, 1 provided These compilation errors resolve around multiprecision. I don't know how to proceed on this error at all. I am currently compiling with the following command: ../b2 -a "cxxflags=-fpermissive -g" "linkflags=-lpthread -lc128 -Wl,-bbigtoc" Any suggestions or advice is appreciated! Thank you for your time! Sincerely, -Axel

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Boost Social Event at CppCon
by Jon Kalb 24 Jun '14

24 Jun '14

Boosters, Because a lot of Boosters are going to be attending CppCon, we¹d like to arrange a social event for Boosters/C++Now regulars. http://cppcon.org/ If you are planning to attend CppCon or even If you are just going to be in or around Bellevue, Washington between September 7th and 12 and you¹d like to join us for dinner, please let us know so we can get a count. Please send mail to: social(a)boost.org Once we settle on a date, etc, we¹ll let everyone who responded know when and where, so please let us know, even if you are a ³maybe.² This year¹s CppCon program includes sessions from a number of Boosters and C++Now regulars with sessions specifically about Boost Libraries. If you are considering attending, please be aware that the Early Bird registration deadline is just days away. http://cppcon.org/registration/ If you are attending, please make your hotel reservations soon. We are likely to sell out of our room block. http://cppcon.org/lodging/ I hope to see you at CppCon. Jon

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[optional] Warnings about uninitialized values
by Andrey Semashev 23 Jun '14

23 Jun '14

Hi, When I use boost::optional I often see gcc warnings about using possibly uninitialized values. I've seen such warnings in my projects outside Boost but now I encountered them in Boost.Log. Building the current develop with gcc 4.8 I see this: ./boost/date_time/constrained_value.hpp: In member function ‘boost::shared_ptr<boost::log::v2_mt_posix::sinks::sink> boost::log::v2_mt_posix:: {anonymous}::default_text_file_sink_factory<CharT>::create_sink(const settings_section&) [with CharT = wchar_t; boost::log::v2_mt_posix:: {anonymous}::default_text_file_sink_factory<CharT>::settings_section = boost::log::v2_mt_posix::basic_settings_section<wchar_t>]’: ./boost/date_time/constrained_value.hpp:76:7: warning: ‘*((void*)& day +2)’ may be used uninitialized in this function [-Wmaybe-uninitialized] value_ = value; ^ libs/log/src/init_from_settings.cpp:172:32: note: ‘*((void*)& day +2)’ was declared here optional< unsigned short > day; ^ libs/log/src/init_from_settings.cpp:249:87: warning: ‘*((void*)& weekday +4)’ may be used uninitialized in this function [-Wmaybe-uninitialized] return sinks::file::rotation_at_time_point(weekday.get(), hour, minute, second); ^ libs/log/src/init_from_settings.cpp:171:37: note: ‘*((void*)& weekday +4)’ was declared here optional< date_time::weekdays > weekday; ^ I attached the full log for convenience. The code in question is this function: https://github.com/boostorg/log/blob/develop/src/init_from_settings.cpp#L171 Note that at line 248 and below I check that the optional is filled before using it, so there is no way I'll be accessing any uninitialized data (that is, if boost::optional behaves correctly). I suspect this may be a compiler bug. I tried to create a minimal example to reproduce it but the warning doesn't show in a simple context. However, I'd like it to be worked around somehow (unless it's an actual bug in boost::optional). Any suggestions? Am I missing a bug in my code?

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[chrono] stopwatches tests failing
by Marcel Raad 22 Jun '14

22 Jun '14

Hi, currently all the stopwatches tests are failing with fatal error C1083: Cannot open include file: 'boost/chrono/stopwatches/stopwatch.hpp': No such file or directory (on MSVC). Apparently no symlink is created for the newly moved stopwatches subdirectory. Unfortunately I have no idea how to tell Boost.Build to do that.

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How to make bjam use gcc instead of g++ using custom compiling and linking options
by Edson Eustachio 22 Jun '14

22 Jun '14

Due to some environment settings I cannot change, I have to build a lib using bjam instead of make. In my own development environment, I have a Makefile that can successfuly build the lib with the following options: gcc -x c -fPIC -shared -w -I include -o libfmtkit.so -lm src/fm5x.c src/fmTXT.c src/fmAiq.c src/fmArray.c src/fmCalc.c src/fmCandle.c src/fmCT.c src/fmCSI.c src/fmDate.c src/fmDJ.c src/fmFile.c src/fmFin.c src/fmFS.c src/fmPNF.c src/fmStr.c src/fmTc.c src/fmTrade.c src/fmTT.c So, I want to reproduce the options above in a Jamfile The first step is replace g++ by gcc. I've already found this can be done adding the rule using gcc But when I do that I got : $ bjam error: at /usr/share/boost-build/build/project.jam:825 error: duplicate initialization of gcc with the following parameters: error: version = 4.4.3 So, I conclude I am already using gcc instead g++. Is that right? The second step is overwrite the options -fPIC -shared -w to the my Jamfile Below is the Jamfile: lib fmtkit : src/fm5x.c src/fmAiq.c src/fmArray.c src/fmCSI.c src/fmCT.c src/fmCalc.c src/fmCandle.c src/fmChartW.c src/fmDJ.c src/fmDate.c src/fmFS.c src/fmFile.c src/fmFin.c src/fmGraph.c src/fmPNF.c src/fmStr.c src/fmTT.c src/fmTXT.c src/fmTc.c src/fmTrade.c : <include>include : <link>shared; I've passed thru the boost documentation but I've not found or I'm not able to understand how to do that into my Jamfile. Does anyone have some clue of where should I find instructions to setting that? This is the output I get when I try to build the lib using the Jamfile described above: $ bjam...found 81 targets......updating 3 targets... gcc.compile.c bin/gcc-4.4.3/debug/fmChartW.oIn file included from src/fmChartW.c:7: include/fmChartW.h:163: error: expected ')' before 'hdc' include/fmChartW.h:166: error: expected ')' before 'hdc' include/fmChartW.h:175: error: expected ')' before 'hdc' include/fmChartW.h:176: error: expected ')' before 'hdc' src/fmChartW.c:13: error: expected ')' before 'hdc' src/fmChartW.c:300: error: expected ')' before 'hdc' src/fmChartW.c: In function 'fmChartScreenInit': src/fmChartW.c:323: warning: implicit declaration of function 'malloc' src/fmChartW.c:323: warning: incompatible implicit declaration of built-in function 'malloc' src/fmChartW.c:329: warning: implicit declaration of function 'free' src/fmChartW.c:329: warning: incompatible implicit declaration of built-in function 'free' src/fmChartW.c: In function 'fmChartScreenClose': src/fmChartW.c:350: warning: incompatible implicit declaration of built-in function 'free' src/fmChartW.c: At top level: src/fmChartW.c:396: error: expected ')' before 'hdc' src/fmChartW.c:604: error: expected ')' before 'hdc' "g++" -x c -O0 -fno-inline -Wall -g -fPIC -I"include" -c -o "bin/gcc-4.4.3/debug/fmChartW.o" "src/fmChartW.c" ...failed gcc.compile.c bin/gcc-4.4.3/debug/fmChartW.o... gcc.compile.c bin/gcc-4.4.3/debug/fmGraph.o ... src/fmGraph.c:2544: error: 'fmSCALETYPESEMILOG' undeclared (first use in this function) src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2546: error: dereferencing pointer to incomplete type src/fmGraph.c:2547: error: dereferencing pointer to incomplete type src/fmGraph.c:2551: error: dereferencing pointer to incomplete type src/fmGraph.c:2551: error: dereferencing pointer to incomplete type src/fmGraph.c:2551: error: dereferencing pointer to incomplete type src/fmGraph.c:2551: error: dereferencing pointer to incomplete type src/fmGraph.c:2551: error: dereferencing pointer to incomplete type src/fmGraph.c:2551: error: dereferencing pointer to incomplete type src/fmGraph.c:2552: error: dereferencing pointer to incomplete type src/fmGraph.c: In function 'fmGraphYpos': src/fmGraph.c:2565: error: 'fmSCALETYPESEMILOG' undeclared (first use in this function) src/fmGraph.c:2573: error: 'fmSCALETYPEINVERTED' undeclared (first use in this function) "g++" -x c -O0 -fno-inline -Wall -g -fPIC -I"include" -c -o "bin/gcc-4.4.3/debug/fmGraph.o" "src/fmGraph.c" ...failed gcc.compile.c bin/gcc-4.4.3/debug/fmGraph.o......skipped <pbin/gcc-4.4.3/debug>libfmtkit.so for lack of <pbin/gcc- 4.4.3/debug>fmChartW.o......failed updating 2 targets......skipped 1 target... Thanks in advance

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big problem with dependency changes
by Robert Ramey 21 Jun '14

21 Jun '14

Currently the master branch has a few problems. Here is one typical example. My project uses the current master to provide boost libraries which I'm not working on. One file has the statement #include <boost/utility/enable_if.hpp> which fails to compile since boost/utility/enable_if.hpp has been moved to core. This raises a few questions. a) Isn't the master branch always supposed to be working? b) There are a lot of intermediate checkins which break the master. Should these be done an a branch and, once they are believed to be all correct, merged in as a group. This would support the concept a) above. c) will I have to change code in the library I maintain to manually change all occurrences of #include <boost/utility/enable_if.hpp> to #include <boost/core/enable_if.hpp> ? d) Why are the tests on the master branch passing? Robert Ramey -- View this message in context: http://boost.2283326.n4.nabble.com/big-problem-with-dependency-changes-tp46… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Efficient tuple implementation
by Louis Dionne 20 Jun '14

20 Jun '14

Hi, I recently discovered (or maybe not) a neat trick to implement a tuple-like container. The technique has a couple of drawbacks which I will explain later. For a real example, you can see my list implementation in Boost.Hana at [1]. Here's the idea: auto list = [](auto ...xs) { return [=](auto access) { return access(xs...); }; }; auto head = [](auto xs) { return xs([](auto first, auto ...rest) { return first; }); }; auto tail = [](auto xs) { return xs([](auto first, auto ...rest) { return list(rest...); }); }; auto length = [](auto xs) { return xs([](auto ...z) { return sizeof...(z); }); }; // etc... // then use it like auto three = length(list(1, '2', "3")); The idea is to use the capture of the lambda as a fast compiler-generated struct with the desired members. By passing a function to that lambda, we get an access to the unpacked representation of those members and we can then apply any fast algorithm on parameter packs. Drawbacks --------- 1. The type of that tuple is completely opaque. Hence, it is harder to debug, but I'm working on other stuff that should make this a moot point. 2. Since lambdas can't be made constexpr, this tuple can't either. However, there was some discussion about proposing constexpr lambdas at C++Now and it looked like there was a lot of support for the idea, so this might change. Benchmarks ---------- I ran a couple of benchmarks testing the compilation time and the results are self explanatory. The benchmark suite is at [2]. ## Create a tuple of n elements The test code looks like: #include <boost/tuple/tuple.hpp> int main() { auto go = boost::make_tuple(1, ..., n); } <a href="http://imgur.com/rKqmvk3"><img src="http://i.imgur.com/rKqmvk3.png"/></a> ## Access the last element of a tuple of n elements The test code looks like: #include <boost/tuple/tuple.hpp> int main() { auto go = boost::make_tuple(1, ..., n); auto last = boost::get<n-1>(go); } <a href="http://imgur.com/b4rWR4y"><img src="http://i.imgur.com/b4rWR4y.png"/></a> Also, for those following the development of Boost.Hana, it is going well and I am preparing for a followup in the near future. Stay tuned! Regards, Louis Dionne [1]: http://github.com/ldionne/hana/blob/master/include/boost/hana/list.hpp [2]: http://github.com/ldionne/benchcc/tree/master/benchmarks

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[optional] Add Optional to BoostBook subset of Boost C++ Libraries
by Andrzej Krzemienski 20 Jun '14

20 Jun '14

Hi, I am looking at this documentation index: http://www.boost.org/doc/libs/develop/doc/html/index.html And I can see that Optional is not included. Could someone add it there, or is there any criterion why certain libraries don't make it in? Regards, &rzej

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