Add preprocessor definitions to FetchContent in cmake-CodePudding

I'm using CMake to compile my C project and I have dependency, which is downloaded using FetchContent, but by default, that dependency is using exceptions, that are disabled in my project and so I have to pass preprocessor definition to this dependency to disable them. This is what I do:

FetchContent_Declare(
  sioclient
  GIT_REPOSITORY https://github.com/socketio/socket.io-client-cpp.git
  GIT_TAG        3.1.0
)

FetchContent_MakeAvailable(sioclient)

add_compile_definitions("_WEBSOCKETPP_NO_EXCEPTIONS_")

Looks like CMake passes add_compile_definitions into anything in my project, but not into dependency. How can I set preprocessor definitions for dependencies downloaded and populated by FetchContent?

CodePudding user response：

It seams to work when add_compile_definitions(_WEBSOCKETPP_NO_EXCEPTIONS_) is added before the FetchContent stuff.

Or alternatively, it works with a target specific definition: target_compile_definitions(sioclient PUBLIC _WEBSOCKETPP_NO_EXCEPTIONS_)