Link errors when compiling cpp file with emcc -s USE_BOOST_HEADERS=1 in Windows

[twopelu]

I'm trying to compile a cpp file to make some tests with the Boost library port for Emscripten in C++ but I get link errors when trying to compile it in Windows with the emcc command.

I think I'm missing some includes or links but I can't find the way to make it work and I can't find any documentation except the Emcscripten guide:

https://emscripten.org/docs/compiling/Building-Projects.html#emscripten-ports

https://emscripten.org/docs/getting_started/FAQ.html#how-do-i-link-against-system-libraries-like-sdl-boost-etc

I have seen other posts with solutions for cmake but for for plain emcc in Windows.

Code

https://www.boost.org/doc/libs/1_48_0/libs/locale/doc/html/hello_8cpp-example.html

Emcc

emcc boost_suite.cpp -s USE_BOOST_HEADERS=1 -s LLD_REPORT_UNDEFINED -o target/boost_suite.html

Errors

 D:\DANI\wasm\boostsuite>emcc boost_suite.cpp -s USE_BOOST_HEADERS=1 -s LLD_REPORT_UNDEFINED -o target/boost_suite.html
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::generator::generator()
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::generator::~generator()
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::generator::generate(std::__2::basic_string<char, std::__2::char_traits<char>, std::__2::allocator<char> > const&) const
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::get(std::__2::ios_base&)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::display_flags(unsigned long long)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::get(std::__2::ios_base&)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::display_flags(unsigned long long)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::get(std::__2::ios_base&)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::display_flags(unsigned long long)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::get(std::__2::ios_base&)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::display_flags(unsigned long long)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::get(std::__2::ios_base&)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::domain_id() const
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::converter<char>::id
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::details::format_parser::format_parser(std::__2::ios_base&, void*, void (*)(void*, std::__2::locale const&))
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::details::format_parser::set_one_flag(std::__2::basic_string<char, std::__2::char_traits<char>, std::__2::allocator<char> > const&, std::__2::basic_string<char, std::__2::char_traits<char>, std::__2::allocator<char> > const&)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::details::format_parser::get_position()
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::details::format_parser::~format_parser()
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::ios_info::get(std::__2::ios_base&)
    wasm-ld: error: C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o: undefined symbol: boost::locale::details::format_parser::restore()
    wasm-ld: error: too many errors emitted, stopping now (use -error-limit=0 to see all errors)
    emcc: error: 'D:/DANI/wasm/emsdk/upstream/bin\wasm-ld.exe -o target/boost_suite.wasm C:\Users\dani\AppData\Local\Temp\emscripten_temp_7wl1l58q\boost_suite_0.o -LD:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libboost_headers.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libgl.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libal.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libhtml5.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libc.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libcompiler_rt.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libc++-noexcept.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libc++abi-noexcept.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libdlmalloc.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libc_rt_wasm.a D:\DANI\wasm\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\libsockets.a -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --allow-undefined-file=C:\Users\dani\AppData\Local\Temp\tmp2cj831u_.undefined --strip-debug --export main --export emscripten_stack_get_end --export emscripten_stack_get_free --export emscripten_stack_init --export stackSave --export stackRestore --export stackAlloc --export __wasm_call_ctors --export fflush --export __errno_location --export malloc --export free --export setThrew --export-table -z stack-size=5242880 --initial-memory=16777216 --entry=main --max-memory=16777216 --global-base=1024' failed (1)
(both examples taken from the official documentation)

[twopelu]

I have found that Locale library is not header-only so it should be compiled as per Boost documentation. How can this be done with emcc so that the ported library can be linked?

https://www.boost.org/doc/libs/1_55_0/more/getting_started/windows.html#header-only-libraries

[twopelu]

https://stackoverflow.com/questions/66292106/link-errors-with-boost-port-of-header-only-libraries-for-emscripten-in-c-was

[twopelu]

I have found that Locale library is not header-only so it should be compiled as per Boost documentation. How can this be done with emcc so that the ported library can be linked?

https://www.boost.org/doc/libs/1_55_0/more/getting_started/windows.html#header-only-libraries

I was wrong, I think Locale should work with headers only flag because there is a locale.hpp file. Maybe it is missing in the port? Is there any way to add it to the compilation? (I have tried with -I but it doesn't work either).

[sbc100]

If the library was header-only then you wouldn't get link errors. Undefined symbols at link time mean you are missing some compiled code.

The USE_BOOST_HEADERS option that emcc has, and the port that lives in tools/ports/boost_headers.py is obviously limited in that only supplied headers. If you want to link aginst libraries that are not header-only you would need to build and link your own copy of boost (i.e. and avoid using the USE_BOOST_HEADERS option), or update the tools/ports/boost_headers.py to include and build sources too.

[FrozenSource]

Hi Guys,

@twopelu Did you ever get this working? I am trying to use boost-locale but as you specified some libraries unlike for example unordered_set (which I succeeded in) are not header only libraries.... however they are provided by the port which in that case is a bit strange.

@sbc100 I am trying to accomplish this all with cmake and as such will need to run cross-platform. I don't know how I would go about modifying that boost_headers.py file to accomplish getting these non-header only libraries to work in WASM. Can you provide any help in this?

Sincerely,

[sbc100]

We try to avoid using cmake in tools/ports because we don't want to have dependencies on cmake and make/ninja there. We just compile the sources we need using ports.run_commands() and ports.create_lib(). See the other ports such as zlib.py for an example of how to do this.

It could be the you will want to avoid boost_headers.py completely and instead write you own external script to build and install boost inside the emscripten sysroot.

[twopelu]

Hi Guys,

@twopelu Did you ever get this working? I am trying to use boost-locale but as you specified some libraries unlike for example unordered_set (which I succeeded in) are not header only libraries.... however they are provided by the port which in that case is a bit strange.

Sincerely,

Hi @FrozenSource, I gave up, I was not able to make it work, but I would like to get back to it if somebody finds the way :-)