2

I try to build the example code provide by boost asio example: http://www.boost.org/doc/libs/1_54_0/doc/html/boost_asio/example/cpp11/spawn/echo_server.cpp

I copy all the code and put it into a cpp file, compile it on linux with gcc4.7 and cmake, link with boost coroutine and boost context library, but the link is failed.

The output is list below:

Linking CXX executable ../../../output/bin/unit_test
cd /home/watson/ID_project/build/server_linux_makefile_gcc/abc/test/unit/abc_async && /usr/local/bin/cmake -E cmake_link_script CMakeFiles/unit_test.dir/link.txt --verbose=1
/usr/bin/c++   -std=c++11 -O3 -DNDEBUG  -pthread -lrt -ltcmalloc -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-free CMakeFiles/unit_test.dir/TestFileChannel.cpp.o CMakeFiles/unit_test.dir/TestStreamBuffer.cpp.o CMakeFiles/unit_test.dir/TestTimer.cpp.o CMakeFiles/unit_test.dir/TestThreadPool.cpp.o CMakeFiles/unit_test.dir/TestScheduler.cpp.o CMakeFiles/unit_test.dir/PCH.cpp.o CMakeFiles/unit_test.dir/main.cpp.o CMakeFiles/unit_test.dir/TestUDPNetwork.cpp.o CMakeFiles/unit_test.dir/TestTCPNetwork.cpp.o  -o ../../../output/bin/unit_test -rdynamic ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_unit_test_framework-gcc47-mt-1_54.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_context-gcc47-mt-1_54.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_coroutine-gcc47-mt-1_54.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_thread-gcc47-mt-1_54.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_filesystem-gcc47-mt-1_54.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libyaml-cpp.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libmongoc.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_system-gcc47-mt-1_54.a ../../../../../../install/thirdparty_linux_makefile_gcc/lib/libprotobuf.a
../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_coroutine-gcc47-mt-1_54.a(coroutine_context.o): In function `boost::coroutines::detail::coroutine_context::coroutine_context(void (*)(long), boost::coroutines::stack_context*)':
coroutine_context.cpp:(.text+0x103): undefined reference to `make_fcontext'
../../../../../../install/thirdparty_linux_makefile_gcc/lib/libboost_coroutine-gcc47-mt-1_54.a(coroutine_context.o): In function `boost::coroutines::detail::coroutine_context::jump(boost::coroutines::detail::coroutine_context&, long, bool)':
coroutine_context.cpp:(.text+0x1bc): undefined reference to `jump_fcontext'
collect2: error: ld returned 1 exit status
make[2]: *** [abc/output/bin/unit_test] Error 1

I print the symbol table from the .a file, and find the symbol jump_fcontext' andmake_fcontext' is existed:

nm libboost_context-gcc47-mt-1_54.a

make_x86_64_sysv_elf_gas.o:
                 U _GLOBAL_OFFSET_TABLE_
                 U _exit
000000000000002e t finish
0000000000000000 T make_fcontext

jump_x86_64_sysv_elf_gas.o:
0000000000000000 T jump_fcontext

Someone can give me any tips about it? I try google every place but without information.

Sam Miller
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watson
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2 Answers2

8

Try swapping the linking order of boost_context and boost_coroutine.

The linker documentation states:

[...] the linker searches and processes libraries and object files in the order they are specified. Thus, ‘foo.o -lz bar.o’ searches library ‘z’ after file foo.o but before bar.o. If bar.o refers to functions in ‘z’, those functions may not be loaded.

In this case Boost.Coroutine depends on Boost.Context. As such, boost_coroutine should appear before boost_context when linking. For more linker ordering details, consider reading this answer.

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Tanner Sansbury
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0

Just to add another possibility for this (specifically with the Boost Context library) - if building under MinGW on Windows, using an earlier version of MASM can produce static libraries that contain no linkable symbols due to the way the symbols are exported.

The solution is to rebuild Boost Context with MASM 8.

See the answer at https://stackoverflow.com/a/26874113/1678468 for more about this.

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Riot
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