cmake下编译的链接库undefined reference

Question

问题遇到的现象和发生背景

因为科研，我编译了github项目seahorn，在最后一步linker的时候，出现undefined reference

运行结果及报错内容

[build] [ 98%] Built target SeaDsaAnalysis
[build] [ 98%] Linking CXX executable ../../bin/seapp
[build] ../../lib/libSeaTransformsScalar.a(PromoteVerifierCalls.cc.o): In function ‘seahorn::PromoteVerifierCalls::runOnFunction(llvm::Function&)':
[build] PromoteVerifierCalls.cc:(.text._ZN7seahorn20PromoteVerifierCalls13runOnFunctionERN4llvm8FunctionE+0x925): undefined reference to ’seahorn::isPartialFn(llvm::Function const&)'
[build] clang: error: linker command failed with exit code 1 (use -v to see invocation)
..
[build] make: *** [seapp] Error 2
[build] Build finished with exit code 2

我的解答思路和尝试过的方法

我最后链接的是可执行文件是seapp，他需要若干个静态库，其中一个就是libSeaTransformsScalar.a。文件PromoteVerifierCalls是该库中的一个，需要调用另外一个静态libSeaInstrumentation.a的GeneratePartialFnPass.c文件，未定义的函数isPartialFn就在GeneratePartialFnPass中。

其中，另外一个可执行文件seahorn也是如此配置（依赖相同的静态库），他就可以成功链接（没有调用到函数isPartialFn）。
还有一个奇怪的现象，我使用nm fine.a查看库的接口，出现了许多奇怪的信息。如下
运行 nm libSeaInstrumentation

...
GeneratePartialFnPass.cc.o:
0000000000000000 V _ZN4llvm30VerifyDisableABIBreakingChecksE
0000000000000000 T _ZN4llvm35initializeGeneratePartialFnPassPassERNS_12PassRegistryE
0000000000000000 W _ZN4llvm4Pass14doFinalizationERNS_6ModuleE
0000000000000000 W _ZN4llvm4Pass16doInitializationERNS_6ModuleE
0000000000000000 W _ZN4llvm8CallInst6CreateEPNS_12FunctionTypeEPNS_5ValueENS_8ArrayRefIS4_EENS5_INS_17OperandBundleDefTIS4_EEEERKNS_5TwineEPNS_11InstructionE

自信看，出现了很多前缀。
我查看别的项目的lib，人家就是这样的

free_var_collector.o:
                 U _GLOBAL_OFFSET_TABLE_
                 U alloc_pstack_array
0000000000000b50 T cleanup_fvar_collector
00000000000000c0 T delete_fvar_collector
                 U delete_harray_store
                 U delete_pstack
                 U delete_ptr_hmap
                 U free_pstack_array
0000000000000020 t fvar_dead_harray
0000000000000000 t fvar_dead_hmap_pair
0000000000000100 T get_free_vars_of_term
                 U harray_remove_elem
0000000000000090 T init_fvar_collector

我的问题出在哪里了？
附件
seapp 的CMakeLists.txt

set (USED_LIBS 
  SeaInstrumentation      被引用的库
  SeaTransformsScalar  这里出问题了
  SeaTransformsUtils
  SeaAnalysis
  SeaSmt
  ${SEA_DSA_LIBS}  
  SeaSupport
  ${LLVM_SEAHORN_LIBS}
  ${Boost_SYSTEM_LIBRARY}
  SeaLlvmIpo
  ${GMP_LIB}
  ${RT_LIB}
  )

set(LLVM_LINK_COMPONENTS
  BitWriter
  IRReader
  IPO
  ScalarOpts
  Instrumentation 
  Core 
  # XXX not clear why these last two are required
  CodeGen
  ObjCARCOpts)
  
add_llvm_executable(seapp DISABLE_LLVM_LINK_LLVM_DYLIB seapp.cc)
target_link_libraries (seapp PRIVATE ${USED_LIBS})
llvm_config (seapp ${LLVM_LINK_COMPONENTS})
install(TARGETS seapp RUNTIME DESTINATION bin)

if (SEAHORN_STATIC_EXE)
  set (CMAKE_EXE_LINKER_FLAGS "-static -static-libgcc -static-libstdc++")
  set_target_properties (seapp PROPERTIES LINK_SEARCH_START_STATIC ON)
  set_target_properties (seapp PROPERTIES LINK_SEARCH_END_STATIC ON)
endif()

编辑libSeaTransformsScalar的CMakeLists.txt

add_llvm_library (SeaTransformsScalar DISABLE_LLVM_LINK_LLVM_DYLIB
  ..
  LowerLibCxxAbiFunctions.cc
  PromoteVerifierCalls.cc 这个文件中引用了isPartialFn
  CutLoops.cc
  PromoteMalloc.cc
  ..
  )

被引用的SeaInstrumentation 的CMakeLists.txt

add_llvm_library(SeaInstrumentation DISABLE_LLVM_LINK_LLVM_DYLIB 
  ...
  BranchSentinelPass.cc
  GeneratePartialFnPass.cc 这里定义了isPartialFn
  )

Answer 1

你的库有前缀是因为函数重载，用g++编译时，符号表中除了函数名，还有返回类型和参数类型；而别人的库是gcc编译的，C语言没有函数重载，符号表中只有函数名。你在调别人的头文件时，加上extern "C"试试。