custom command not getting executed while building.

Code
1

Hello all,

I got provided with many CMakeLists files which on building generate a final executable. I am trying to write a custom command which on building should spit out .ll files from the C files, so I can be using those ll files for further analysis purposes.

Below is the code for the same, where sources is a variable that contains the list of C files, while the private_headers contain the header files.

add_library(target_name SHARED ${sources} ${private_headers})

foreach(C_FILE ${sources})
  get_filename_component(EXT ${C_FILE} LAST_EXT)
  if(".c" STREQUAL ${EXT})
    get_filename_component(C_FILE_NAME ${C_FILE} NAME_WE)
    set(LL_FILE ${C_FILE_NAME}.ll)
${CMAKE_CURRENT_SOURCE_DIR}/${C_FILE}")
    add_custom_command(
      TARGET target_name
      POST_BUILD
      COMMAND /usr/bin/clang -c -emit-llvm  ${CMAKE_CURRENT_SOURCE_DIR}/${C_FILE}
      DEPENDS  ${CMAKE_CURRENT_SOURCE_DIR}/${C_FILE} ${sources} ${private_headers} 
      WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
      )
    endif()
endforeach()

There is no issue in the above as a SHARED library is getting created and the custom command is getting executed successfully POST_BUILD.

But there are a few files where the add_library is creating an INTERFACE instead and interfaces don’t support the PRE/POST_BUILD.

So to get around it I create a custom_target which depends on that library as below

add_library(inter_lib INTERFACE)
add_custom_target(my_target DEPENDS inter_lib)

and now I am trying to run the custom command using the above target name (my_target in this case) but the custom commands are not getting executed.

Can anyone help me with where exactly I am going wrong in this case? I also can’t explicitly change the library type from INTERFACE to STATIC or SHARED as it may have some adverse effect on the analysis.

Thank you.

2

For the INTERFACE case, I’m assuming you don’t use the POST_BUILD keyword in your add_custom_target() call (it wouldn’t make sense, if I understand your scenario correctly)? Does adding ALL to your add_custom_target() call give you the behavior you’re looking for?

3

Besides the target-level question, I just want to note that I think this is also missing any flags that come from the target itself (and therefore any inherited usage requirements). Source-specific flags are also being lost here.

4

Sorry for the late reply. But add_custom_target did work but I had to remove the depends on the interface to make it work. This was just a small test sample to make sure whether the required files are getting generated or not. So I can’t comment how it will play in the big picture.