C++: why do we use CMake OBJECT library?

[KrisThielemans]

The generated CMakeLists.txt uses an OBJECT library, e.g. see https://github.com/microsoft/yardl/blob/bf7068e93bb2115cbf731037ed1d75710d795679/cpp/evolution/v2/generated/CMakeLists.txt#L26C1-L32C2

This possibly avoids some issues, but it causes others, including the need for (unexpected) target_include_directories, as in

set(PETSIRD_dir ../PETSIRD/cpp/generated)
add_subdirectory(${PETSIRD_dir} PETSIRD_generated)

add_executable(my_target blabla.cpp)
# without the following, generated include files are not found
target_include_directories(my_target PUBLIC ${PETSIRD_dir})

If OBJECT library is best, there probably should be a variable <libraryname>_INCLUDE_DIRS, which might be expected.

(Is the need for the target_include_directories documented?)

[johnstairs]

I think we can fix this in the object library library. I will take a look.

[KrisThielemans]

#104 asked for adding target_include_directories, but that doesn't seem to work for OBJECT libraries.

[johnstairs]

(And the idea with the object library is to make it easier to incorporate the generated code, but you are not required to use it)