Cannot mark vcpkg include directories as SYSTEM; third-party warnings become errors with /W4 /WX

[MackBambu]

I am using vcpkg to manage dependencies for my project. Due to project requirements, I enabled /W4 and /WX to treat all warnings as errors. However, this causes warnings from third-party headers installed by vcpkg to also be treated as errors, which breaks the build.

I attempted to exclude these include directories by marking them as system headers using target_include_directories(... SYSTEM ...), but this does not work. It seems that vcpkg’s include paths are added before my own CMake commands, so my SYSTEM specification is not applied to them.

Is there a recommended way to mark all vcpkg-installed include directories as SYSTEM (or otherwise suppress warnings from vcpkg headers) so that they are not affected by /WX?

Any guidance or an official solution would be greatly appreciated.