September 2025 - Boost-users

Crocc-compiling Boost from Linux for windows
by niXman 16 Sep '25

16 Sep '25

Hi, I'm trying to build Boost from Linux for Windows. I created user-config.jam file with the following content: using gcc : mingw : x86_64-w64-mingw32-g++ : <rc>x86_64-w64-mingw32-windres <as>x86_64-w64-mingw32-as ; I build using this command line: ./b2 --user-config=./user-config.jam --prefix=$HOME/boost-1.82.0 target-os=windows address-model=64 variant=release install but I get these messages when building boost.context: gcc.compile.asm bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/ontop_x86_64_sysv_elf_gas.o ontop_x86_64_sysv_elf_gas.S: Assembler messages: ontop_x86_64_sysv_elf_gas.S:43: Warning: .type pseudo-op used outside of .def/.endef: ignored. ontop_x86_64_sysv_elf_gas.S:43: Error: junk at end of line, first unrecognized character is `o' libs/context/src/asm/ontop_x86_64_sysv_elf_gas.S:135: Warning: .size pseudo-op used outside of .def/.endef: ignored. libs/context/src/asm/ontop_x86_64_sysv_elf_gas.S:135: Error: junk at end of line, first unrecognized character is `o' libs/context/src/asm/ontop_x86_64_sysv_elf_gas.S:138: Error: junk at end of line, first unrecognized character is `-' "x86_64-w64-mingw32-g++" -x assembler-with-cpp -m64 -mthreads -O3 -finline-functions -Wno-inline -Wall -fvisibility=hidden -DBOOST_ALL_NO_LIB=1 -DBOOST_CONTEXT_SOURCE -DBOOST_DISABLE_ASSERTS -DNDEBUG -D_WIN32_WINNT=0x0601 -I"." -c -o "bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/ontop_x86_64_sysv_elf_gas.o" "libs/context/src/asm/ontop_x86_64_sysv_elf_gas.S" ...failed gcc.compile.asm bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/ontop_x86_64_sysv_elf_gas.o... gcc.compile.asm bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/make_x86_64_sysv_elf_gas.o make_x86_64_sysv_elf_gas.S: Assembler messages: make_x86_64_sysv_elf_gas.S:44: Warning: .type pseudo-op used outside of .def/.endef: ignored. make_x86_64_sysv_elf_gas.S:44: Error: junk at end of line, first unrecognized character is `m' libs/context/src/asm/make_x86_64_sysv_elf_gas.S:144: Warning: .size pseudo-op used outside of .def/.endef: ignored. libs/context/src/asm/make_x86_64_sysv_elf_gas.S:144: Error: junk at end of line, first unrecognized character is `m' libs/context/src/asm/make_x86_64_sysv_elf_gas.S:147: Error: junk at end of line, first unrecognized character is `-' "x86_64-w64-mingw32-g++" -x assembler-with-cpp -m64 -mthreads -O3 -finline-functions -Wno-inline -Wall -fvisibility=hidden -DBOOST_ALL_NO_LIB=1 -DBOOST_CONTEXT_SOURCE -DBOOST_DISABLE_ASSERTS -DNDEBUG -D_WIN32_WINNT=0x0601 -I"." -c -o "bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/make_x86_64_sysv_elf_gas.o" "libs/context/src/asm/make_x86_64_sysv_elf_gas.S" ...failed gcc.compile.asm bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/make_x86_64_sysv_elf_gas.o... gcc.compile.asm bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/jump_x86_64_sysv_elf_gas.o jump_x86_64_sysv_elf_gas.S: Assembler messages: jump_x86_64_sysv_elf_gas.S:44: Warning: .type pseudo-op used outside of .def/.endef: ignored. jump_x86_64_sysv_elf_gas.S:44: Error: junk at end of line, first unrecognized character is `j' libs/context/src/asm/jump_x86_64_sysv_elf_gas.S:139: Warning: .size pseudo-op used outside of .def/.endef: ignored. libs/context/src/asm/jump_x86_64_sysv_elf_gas.S:139: Error: junk at end of line, first unrecognized character is `j' libs/context/src/asm/jump_x86_64_sysv_elf_gas.S:142: Error: junk at end of line, first unrecognized character is `-' "x86_64-w64-mingw32-g++" -x assembler-with-cpp -m64 -mthreads -O3 -finline-functions -Wno-inline -Wall -fvisibility=hidden -DBOOST_ALL_NO_LIB=1 -DBOOST_CONTEXT_SOURCE -DBOOST_DISABLE_ASSERTS -DNDEBUG -D_WIN32_WINNT=0x0601 -I"." -c -o "bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/jump_x86_64_sysv_elf_gas.o" "libs/context/src/asm/jump_x86_64_sysv_elf_gas.S" ...failed gcc.compile.asm bin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden/asm/jump_x86_64_sysv_elf_gas.o... ...skipped <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>libboost_context.a(clean) for lack of <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>asm/make_x86_64_sysv_elf_gas.o... ...skipped <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>libboost_context.a for lack of <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>asm/make_x86_64_sysv_elf_gas.o... ...skipped <p/home/andrew/boost-1.82.0/lib>libboost_context.a for lack of <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>libboost_context.a... ...skipped <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>libboost_context-variant-static.cmake for lack of <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>libboost_context.a... ...skipped <p/home/andrew/boost-1.82.0/lib/cmake/boost_context-1.82.0>libboost_context-variant-static.cmake for lack of <pbin.v2/libs/context/build/gcc-mingw/release/link-static/target-os-windows/threading-multi/visibility-hidden>libboost_context-variant-static.cmake... ...failed updating 3 targets... ...skipped 5 targets... any ideas how can I fix it? best!

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[Regex] Undefined symbols when using Boost::regex_icu from CMake
by Lipódi László 11 Sep '25

11 Sep '25

Dear Boost::regex_icu users! I've ran into a problem while using the regex library of Boost with ICU compatibility mode. I am getting a lot of linker errors about ICU functions. This is all the linker errors I get: https://pastebin.com/eCj8Pi2m I am pretty sure that I'm getting this while using `boost::u32regex_token_iterator`. I'm using CMake to build my project and CPM (A wrapper around FetchContent). Here is my CMakeLists.txt: ``` cmake_minimum_required(VERSION 3.12) project(termeszetes_nyelvi) include(cmake/CPM.cmake) set(CMAKE_CXX_STANDARD 26) set(BOOST_REGEX_STANDALONE ON) set(ICU_ROOT "C:/Program Files/icu") CPMAddPackage("gh:boostorg/regex#boost-1.89.0") add_executable(termeszetes_nyelvi main.cpp regex_utils/regex_match_collector.hpp regex_utils/split_string_using_regex.hpp print_utils/format_map.hpp) target_link_libraries(termeszetes_nyelvi PRIVATE Boost::regex_icu)``` I have tried linking to all ICU components, but it did not resolve my errors. This is the function template that causes the error: https://gist.github.com/nevemlaci/3a1a14516626b263f11e887f9433cfd4 Please tell me if you need any more details. Thank you in advance, Laci

2 2

Radix Trie
by Pavel Vazharov 10 Sep '25

10 Sep '25

HI there, Is there a generic radix trie container in boost which can be used for longest prefix match? I mean, I couldn't find one in the boost containers libraries but maybe some library uses such a container internally and it's generic enough to be used with types other than strings? Thanks, Pavel.

4 6

Converting pointer-to-member to member index using Boost.PFR
by mail＠vittorioromeo.com 06 Sep '25

06 Sep '25

Consider the following struct: struct Particle { float scale; float opacity; float rotation; }; I want the following to compile: static_assert(indexOf<&Particle::scale>() == 0); static_assert(indexOf<&Particle::opacity>() == 1); static_assert(indexOf<&Particle::rotation>() == 2); I have managed to implement a working version using Boost.PFR: template <auto PM> consteval int indexOf() { using ClassType = typename PMTraits<decltype(PM)>::ClassType; constexpr ClassType obj{}; std::size_t result = -1; [&]<auto... Is>(std::index_sequence<Is...>) { (..., ( ( static_cast<const void*>(&(boost::pfr::get<Is>(obj))) == static_cast<const void*>(&(obj.*PM)) ) ? (result = Is) : 0 ) ); }(std::make_index_sequence<boost::pfr::tuple_size_v<ClassType>>{}); return result; } But I am displeased of the fact that I do need to create an object of type `ClassType` in order to make `obj.*PM` work. Is there a better way of doing this that (1) does not require the creation of an object at compile-time and/or (2) is more efficient to compile?

2 3

Make io_fields print field names
by Phil Phil 05 Sep '25

05 Sep '25

Greetings, I'd like to replace a call to io_fields like this std::ostream& operator<<(std::ostream& os, const my_struct& x) { return os << boost::pfr::io_fields(x); // Equivalent to: os << "{ " << x.i << " ," << x.s << " }" } In such a way that the names of the fields are printed too so it should something like os << "{ " << "x: " << x.i << " ," << "y: " << x.s << " }" Is this possible and if yes what would be the most straightforward way? Regards

1 0

[boost::locale or boost::nowide] C++23 char8_t. How to convert std::u8string <-> std::string?
by Georg Gast 02 Sep '25

02 Sep '25

Hi, as c++23 is now way out of the door and c++26 is already on the horizon, is there any thing in the boost libraries cor the "new" u8 literal and the new u8strings? I can only find mentioning char8_t in context of boost::filesystem. https://www.boost.org/doc/libs/latest/libs/nowide/doc/html/index.html#using For std::filesystem::path available since C++17 there is no way to imbue a locale. However the u8string() member function can be used to obtain an UTF-8 encoded string from a path. And to obtain a path from an UTF-8 encoded string you may use std::filesystem::u8path or since C++20 one of the path constructors taking a char8_t-type input. But it seems there is nothing like narrow() or widen() to convert from std::u8string <-> std::string (needed for non char8_t aware libraries). Think Win32 API. Is the only recommendation: Just stay on std::string and ignore char8_t? Still in 2025? Even with boost libraries? Bye Georg

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