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Error when trying to build Boost 1.69.0 with LLVM
by Osman Zakir 22 Dec '18

22 Dec '18

When trying to build Boost 1.69.0 with LLVM, I had an error about the "register" keyword, regarding the removal of it in C++17. I searched on the Web and found out that I can use the "-Wno-register" flag to calm down Clang 6.0.0. What do I do in Clang 8.0.0? The same?

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boost_1_19_0 fails to build random using clang-cl
by JR Cary 21 Dec '18

21 Dec '18

This is now more of an FYI, as I can disable random and get the build I need. boost 1_69_0 clang version 8.0.0 (trunk 349323) Windows 10 Build command: ./b2 toolset=clang-win runtime-link=shared link=shared define=BOOST_TEST_DYN_LINK cxxflags='-DBOOST_THREAD_DONT_USE_CHRONO' linkflags='-DBOOST_THREAD_DONT_USE_CHRONO' address-model=64 threading=multi variant=release -s NO_COMPRESSION=1 --layout=system --abbreviate-paths -j2 --without-python --without-mpi --without-log --without-math stage The first error is Creating library bin.v2\libs\random\build\clng-win-8.0.0\rls\adrs-mdl-64\thrd-mlt\boost_random.lib and object bin.v2\libs\random\build\clng-win-8.0.0\rls\adrs-mdl-64\thrd-mlt\boost_random.exp^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptEnumProvidersA referenced in function "public: __cdecl boost::random::random_device::impl::impl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0impl@random_device@random@boost@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptAcquireContextA referenced in function "public: __cdecl boost::random::random_device::impl::impl(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0impl@random_device@random@boost@@QEAA@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptReleaseContext referenced in function "public: __cdecl boost::random::random_device::impl::~impl(void)" (??1impl@random_device@random@boost@@QEAA@XZ)^M random_device.obj : error LNK2019: unresolved external symbol __imp_CryptGenRandom referenced in function "public: unsigned int __cdecl boost::random::random_device::operator()(void)" (??Rrandom_device@random@boost@@QEAAIXZ)^M bin.v2\libs\random\build\clng-win-8.0.0\rls\adrs-mdl-64\thrd-mlt\boost_random.dll : fatal error LNK1120: 4 unresolved externals^M clang-cl: error: linker command failed with exit code 1120 (use -v to see invocation)^M The build succeeds upon adding --without-random to the build invocation. I tried attaching the full log, but then the message was rejected for being too large. ..................John Cary

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Questions about Boost.Multiprecision..
by A Z 20 Dec '18

20 Dec '18

I want to be performing some algebraic functions work on cpp_rational which I will be using templates with the following type to configure precision (and scale?) #include <boost/multiprecision/cpp_int.hpp> in order to avoid the use of floating point types. --What is the #include statement for cpp_rational? I can't manage to find it. -When using non-floating point, is there a method to obtain a variable precision pi, or do I have to use arccos(-1); ? What is the file to import for that? -If I want to import a non-floating-point (cpp_rational) library power, nth root, trigonometry, all the useful function, what is the #include and the file in boost for that?

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Having some trouble with bootstrapping Boost to use LLVM
by Osman Zakir 20 Dec '18

20 Dec '18

I changed the project-config.jam file in my Boost source tree to have Boost.Build use LLVM, but then when I used "bootstrap" command after, I saw that it was still using MSVC. When I looked at the project-config.jam file again at that point, I saw that its content had been reverted back to the default one for building with MSVC. What's going on? What do I need to do? Is there an argument I need to provide to the bootstrap command here so that it'll keep the configuration file content that I want it to? And is there no help command that would let me see what arguments, if any, I can pass to the tool? Another thing I want to ask is whether or not I need to have Boost.Built emit library files with a .bc extension to be able to link them with code I want to build using the Emscripten compiler. I ask because Emscripten needs compiled libraries to have been compiled to LLVM bitcode, and when Emscripten itself does this it adds the .bc extension instead of the .lib one.

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integer_log2.hpp header deprecation using Boost
by Michael Powell 19 Dec '18

19 Dec '18

Hello, I am receiving a deprecation warning: d:\dev\boost.org\boost_1_69_0\boost\pending\integer_log2.hpp(7): note: This header is deprecated. Use <boost/integer/integer_log2.hpp> instead. The immediate includes are these: #include <boost/uuid/uuid.hpp> #include <boost/uuid/uuid_io.hpp> #include <boost/uuid/random_generator.hpp> But I am also leveraging Spirit, Format, Variant, Optional, to name a few, that I can determine. I am not including "integer_log2.hpp" directly, so I wondered which library(ies) might have this as a dependency? Spirit? Phoenix, via Spirit? Format? Thoughts? Suggestions? Cheers, Michael Powell

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odeint: how to solve ODE as you go without deciding upfront what the interval is?
by Yuri 19 Dec '18

19 Dec '18

The function 'integrate' solves ODE for a pre-defined interval of time. What if I don't know what the interval is? I just need a few values, and then I would like to decide if I need more values, and when to stop. I don't want to just solve for some arbitrarily large interval, because this would waste CPU. On the other hand, choosing the shorter original interval and then continuing would introduce unnecessary errors if one would do this too many times. It seems like either the 'observer' function should have another argument: 'stop', or the interface should allow continuation. Yuri

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[Spirit] X3 thread-safety
by Igor R 19 Dec '18

19 Dec '18

Hello, In my project I run x3-based parsers in parallel, using openmp. I've just moved from boost 1.64 to 1.68, and the parsers now cause segfault (heap corruption) - quite consistently, every time I run the program. OTOH, with 1.64 it never crashed. Before I begin to debug it in depth, I'd like to know if there's some known issue with Spirit's thread-safety in Boost 1.68. Did anyone encounter thread-safety issie with the recent Spirit versions? Thanks.

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Build boost asio http server examples single threaded using c++03
by Eric Curtin 19 Dec '18

19 Dec '18

Hi Guys, I was wondering if anyone could help me out building all the boost asio http server examples from: https://github.com/boostorg/asio/tree/develop/example/cpp03/http But catch is, I need to use c++03/98, single threaded without dependencies on std::thread, boost::thread or posix threads. I also need static linking to all the other boost libraries. Also want to compile with g++ -O3 -flto on x86_64 Linux. How can I build these examples like this? This is also a question on stackoverflow: https://stackoverflow.com/questions/53822438/building-boost-asio-without-th… Lets say the build environment is this one: curtine/dockerfiles-fat:ubuntu18.04 Regards, Eric

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[Asio] Combining use_future with strands
by Sorin Fetche 19 Dec '18

19 Dec '18

Hi, Is there a way to combine the special use_future completion token with a strand? Something with the meaning of: - the asynchronous operation should pass the result to the future it returns, and - the internal operations of it (if any) should run in a strand Code snippet: asio::io_context io_context; asio::io_context::strand strand(io_context); std::future<void> f = async_my_operation(io_context, <params>, asio::use_future); //________________________________________How to add the strand here ^^^ ? The code area where I would like to apply this is in this test program: https://github.com/sorf/cpp-dev-new/blob/abf9d831a0b82fb81751eee6cfa498d3b9… The self contained program and its output is here: https://wandbox.org/permlink/pF5Hbm6jqPOmEKbO As a background, the test program I wrote is based on these Boost.Asio examples: - for strand usage (i.e. bind_executor): https://github.com/boostorg/asio/blob/develop/example/cpp03/tutorial/timer5… - for composed operations: https://github.com/boostorg/asio/blob/develop/example/cpp11/operations/comp… and implements a composed operation that runs multiple internal operations in parallel and in series. Similar to the constructor of a socket or a timer object, the operation receives as a parameter an io_context; it doesn't offer an overload that receives a strand object directly. The operation is then tested with callback completion, callback completion in a strand, future and future + strand (where the test fails). Thank you, Sorin

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How to implement a visitor pattern over an AST
by Michael Powell 19 Dec '18

19 Dec '18

Hello, I have an AST successfully building, generating text file, and subsequently Spirit Qi parsing for verification purposes. Now I want to implement a visitor pattern over that AST, somehow... For "calculators" and such, "evaluating" those expressions is one thing; however, this AST is not that. It is closer akin to a parsed Xml or Json model/tree. In other words, I'd like for it to feel sort of like an iterator if that's even possible. It should have contextual awareness where it is at all times, etc, perhaps "incrementing" is a depth first analysis. In particular I have in mind to iterate the expected and actual AST results in order to perform the verification. In other words, I might do something like this: auto expected_it = ast_visitor{&expected}; auto actual_it = ast_visitor{&actual}; REQUIRE(expected_it); REQUIRE(actual_it); REQUIRE(*expected_it == *actual_it); // Rinse and repeat ++expected_it; ++actual_it; REQUIRE(*expected_it == *actual_it); I wonder if something like this is even possible from the Boost libraries? Or interested to hear any insights on the subject. For that matter, I wonder it is more appropriate to simply implement the logical operators. Thanks! Michael Powell

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