C++ - Unable to link in libyaml using Visual Studio 2019/CMake

Question

Attempting to link in libyaml (0.2.5) using Visual Studio 2019 Enterprise and CMake, as I have a cross-platform (Linux/Windows) project that uses this library. According to the documentation, this library should work in Windows 10. It links in just fine on Linux (64-bit machine).

I'm compiling it as a static lib, and it has no issue generating the .lib file. I've copied it to the appropriate location that I'm linking in from my CMakelists.txt, as well as the header.

When I link it in from my project on Windows:

ts.lib(yamlparser.cxx.obj) : error LNK2019: unresolved external symbol __imp_yaml_parser_initialize referenced in function "public: bool __cdecl YAMLParser::parse_cfg(void)" (?parse_cfg@YAMLParser@@QEAA_NXZ)
ts.lib(yamlparser.cxx.obj) : error LNK2019: unresolved external symbol __imp_yaml_parser_set_input_file referenced in function "public: bool __cdecl YAMLParser::parse_cfg(void)" (?parse_cfg@YAMLParser@@QEAA_NXZ)
ts.lib(yamlparser.cxx.obj) : error LNK2019: unresolved external symbol __imp_yaml_parser_scan referenced in function "public: bool __cdecl YAMLParser::parse_cfg(void)" (?parse_cfg@YAMLParser@@QEAA_NXZ)

This is what I'm doing on the CMake side - the very same thing I'm doing to link in my GoogleTest libraries on both Linux and Windows:

if (UNIX)
...
...
else()
  set (MY_LIB_DIR "C:/mylib/lib")
  set (MY_INCLUDE "C:/mylib/include")

  set (YAML_LIB "${MY_LIB_DIR}/yaml.lib")
  set (VCPKG_LIBRARY_LINKAGE static) 
endif()

include_directories(${MY_INCLUDE})

add_library(ts
    ...
    ...
)

add_executable(myexec main.cxx)
target_link_libraries(myexec ts ${YAML_LIB})

VS isn't giving me many clues here except that there's a linkage problem that I can't quite figure out.

Any advice on how I can debug this or what the problem may be?

question from:https://stackoverflow.com/questions/65853628/c-unable-to-link-in-libyaml-using-visual-studio-2019-cmake

Answer 1

The __imp was the clue that my code was trying to include the library dynamically... Opening up yaml.h, I noticed that it tries to export from DLL unless YAML_DECLARE_STATIC is defined. Defined this in CMake and my issue is resolved.