June 2014 - Boost - lists.preview.boost.org

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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[interprocess] Ticket 9414 (32 process communicating with 64 process)
by Joseph Van Riper 20 Jun '14

20 Jun '14

I ran into a problem with message queues that, after a couple of days investigation, lead to finding this bug. I notice that the maintainer has labelled this bug as 'invalid'. I would like to convince the maintainer otherwise. My alternatives are less optimum. I am working on a project where, on a Windows machine, I am running a service that waits for messages on the message queue. On a 32-bit environment, I will not run into any problems. But in a 64-bit environment, I may have either 64-bit or 32-bit clients attempting to write to the message queue, due to the nature of my needs and the nature of the Windows operating system. The messages from the clients are not specific to the bit-ness of the client, but are sent to the server. The server records these messages to a database it maintains. The server then pulls messages from the database and posts it to a web page. As the code stands now, I will have to compile both a 32-bit and 64-bit version of the server to install on 64-bit WinOS boxes, maintaining two separate databases of similar information, which will post to the web site with no sense of co-ordination (and little hope of co-ordination since they can't talk to each other). Or, alternatively, I would have to create my own message queue that doesn't rely upon std::size_t, but perhaps uses boost::uint32_t or boost::uint64_t instead... but it seems silly to me to maintain another message queue when this one is very close to being able to do what I need. I should also point out that I need for this to work in Linux as well, although I don't expect Linux has the Windows annoyance of having to work with two different bit-wise operating systems on one box. At the very least, I'd like a dialog, so I can understand why this defect is considered 'invalid'. Convince me that it really is invalid, and I'll go away. Otherwise, I respectfully argue against it. - Trey

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blincubator comments
by Sohail Somani 19 Jun '14

19 Jun '14

Hi Robert, First of all, great idea and thanks for doing it. The concepts are solid and the site will be a great help for users and authors alike. It appeared that it was not possible to add any reviews anonymously. Is this by design? Does one have to register? It would be clearer if the page was unavailable or that there was a placeholder requiring the visitor to register before they could view the "submit review" page[1]. I closed the page after writing a review and being unable to submit because it seemed the site was buggy and so I set out to submit a report, but maybe the mistake was that I was supposed to have registered first. It was unclear. Also, if you ever do consider writing another version, consider Django because the admin interface[2] could allow you to generate a nice interface without futzing around with plugins and can also help you create a more maintainable site because it forces you into a structure. I'd be happy to help if you choose to go this way. General question: are there any other sites/applications of this kind out there? It seems to be a generally useful thing to make it easier to solicit user contributions for open source software. The closest would be a fork+pull request in Github that people can comment on. Maybe that's enough, I don't know. [1] http://rrsd.com/blincubator.com/review/?library_post_id=769 [2] http://www.djangobook.com/en/2.0/chapter06.html Sohail

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