CODEWITHSUNDEEP
c++buildcmake
Pejman
Pejman

Reputation: 1358

CMake make add_library depend on ExternalProject_Add

TLDR: I would like to ask CMake to wait for ExternalProject_Add to complete before it attempts to move on to the next subdirectory and build a library that happens to use one of the files of the external project. In other words, I like to declare an external project as a dependency for a shared library.

More Description:

Suppose that my CMake project has two directories: thirdparty and src. My top-level CMakeLists.txt file has:

add_subdirectory(thirdparty)
add_subdirectory(src)

thirdparty/CMakeLists.txt contains multiple ExternalProject_Add commands. My original intention was to pull and build all these external projects and then move on to building my own libraries and executables in src. Unfortunately, this didn't go as I planned:

One of my external projects is called libsvm. And my src/CMakeLists.txt has the following:

set(Libsvm_SOURCE_FILES
    ${PROJECT_BINARY_DIR}/thirdparty/libsvm/src/libsvm/svm.cpp
)

include_directories(
    ${Libsvm_INCLUDE_DIR}
)

add_library(
    mysvm
  SHARED
    ${Libsvm_SOURCE_FILES}
)

Now the problem I am facing with is that CMake is unable to find ${Libsvm_SOURCE_FILES}, apparently because this step is being executed before the ExternalProject_Add in my thirdparty/CMakeLists.txt file is executed.

I would like to declare this external project as a dependency for this library.

Broader Question: Is there a clean way to force CMake to finish everything in first subdirectory before moving on to the next? If not, do you recommend that I make any change in the hierarchy and organization of my CMakeLists files?

Thanks!

Upvotes: 2

Views: 1861

Answers (1)

Tsyvarev
Tsyvarev

Reputation: 66288

CMake expects every source file, passed to add_library or add_executable, to be existed unless it is marked as GENERATED. This property is automatically set for files listed as OUTPUT for add_custom_command. In other cases one need to set this property explicitly:

set_source_files_properties(${Libsvm_SOURCE_FILES} PROPERTIES GENERATED TRUE)

Upvotes: 2

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