The environment and version details are mentioned below 

• Visual Studio    - 2019
• MongoDB         - 4.2.7  
• Mongo C          - 1.18.0
• Mongo Cxx       - 3.5.1
• Boost                - 1.70.0
• OS | Windows   - 10

I have mongo c and Boost libraries of versions mentioned above. When Installing mongocxx (version mentioned above), it is throwing error "Must be trivially constructable". I have also tried with other versions(3.5.0, 3.4.1, 3.1.3) of mongo cxx which are also throwing same error.

I have followed the instruction mentioned in the links to install mongoc and mongocxx lbraries.

• mongo c - http://mongoc.org/libmongoc/current/installing.html#building-windows
• mongo cxx - I have used both the links but same reuslt
  • http://mongocxx.org/mongocxx-v3/installation/
  • https://jira.mongodb.org/browse/CXX-19

command used for installing : 

1. cmake -G "Visual Studio 16 2019" -DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_FLAGS="/Zc:__cplusplus" -DBOOST_ROOT=C:\Boost -DCMAKE_PREFIX_PATH=C:\mongo-c-driver -DCMAKE_INSTALL_PREFIX=C:\mongo-cxx-driver ..
2. msbuild.exe ALL_BUILD.vcxproj
3. msbuild.exe INSTALL.vcxproj

Building(step 2) ends in errors.