How to limit compiler flags only to a (my) local library?

Question

I am trying the example below :

add_library(
        mylib
        src/my_code.cpp)

target_include_directories(mylib
        PUBLIC include ${catkin_INCLUDE_DIRS} ${thirdPartyLib_INCLUDE_DIRS})

add_dependencies(
        mylib
        ${mylib_EXPORTED_TARGETS}
        ${catkin_EXPORTED_TARGETS})


target_link_libraries(mylib
        PUBLIC
        ${thirdPartyLib_LIBRARY} ${catkin_LIBRARIES})

target_compile_options(mylib PRIVATE -Werror -Wall -Wextra)

The issue is that the compile options also propagate to thirdPartyLib, yet I need them only for mylib.

Answer 1

I think that the problem is compiler warnings, which are generated by included thirdPartyLib header files when compiling file my_code.cpp.

If you want your compiler not to generate warnings from included third-party header files, you can for example in gcc/clang include them as "system headers" (command line option -isystem instead of -I).

To do this in CMake use SYSTEM option in target_include_directories:

target_include_directories(mylib
    SYSTEM
        PUBLIC ${thirdPartyLib_INCLUDE_DIRS}
)