Describe your problem here.

1. Pull the code from:
   SHA-1: fe3d648

• Merge pull request Support "=" in sub-config file path. #450 from solicomo/=-in-sub-ini-file-path
  Support "=" in sub-config file path

2. Use VS2019 16.4 to open the solution, update the whole project to VS2019

3. Change the C++ language to ISO C++17 Standard (std:c++17) in VS2019

4. compile the static lib "log4cplusS"

5. after I use it in an vs2019 test demo, I have this error:
   error LNK2001: unresolved external symbol "public: __cdecl log4cplus::CallbackAppender::CallbackAppender(void (__cdecl*)(void *,wchar_t const *,wchar_t const *,int,wchar_t const *,wchar_t const *,unsigned __int64,unsigned long,wchar_t const *,wchar_t const *,int),void *)"
   (??0CallbackAppender@log4cplus@@qeaa@P6AXPEAXPEB_W1H11_KK11H@Z0@Z)

The code of 2.0.4 works good without this issue. Could you help me to solve it so I can update my project. Thank you very much.

Also, provide the following information:

• version: the code from:
  SHA-1: fe3d648

• Merge pull request Support "=" in sub-config file path. #450 from solicomo/=-in-sub-ini-file-path
  Support "=" in sub-config file path

• operating system, CPU, bitness: Win10 1909, AMD Ryzen 1950X

• configure script, or CMake, etc., flags and settings: VS2019 16.4 compile the static lib "log4cplusS"

• flags and settings used by your application: None

• compiler and its version: VS2019 16.4