CODEWITHSUNDEEP
cmake
aram
aram

Reputation: 1444

globbing files autogenerated by a sub_directory binary

I have the following problem, I have a separate cmake project that generates c++ files and I want to glob them into a library that uses them. Right now this is done in this manner

add_subdirectory(generator)
add_custom_target(run-generator ... byproduct GENERATED_FILES)
include(files.txt) 
target_link_libraries(library ${GENERATED_FILES})

The include files.txt is actually a set(GENERATED_FILES all_autogen_files), right now they're fixed but in the future they might change. That is what I would want to have is something like

add_subdirectory(generator)
execute_process(generator_binary ... commands)
file(glob ${GENERATED_FILES} output_location_of_gen_files) 
target_link_libraries(library ${GENERATED_FILES})

As I understood execute_process runs on the spot is read, so this would generate all the files before the file(glob) but I don't know how would I go about actually building the generator binary before the execute process, since right now what builds it before is that it is a dependency on the target_link_libraries

Upvotes: 0

Views: 40

Answers (1)

Corristo
Corristo

Reputation: 5520

The only way this could possibly work is if you create a superbuild, i.e. a CMake project that builds everything with ExternalProjects. The reason is that you can't create new targets or add sources to existing targets during the build.

With a superbuild you need at least 3 separate CMake projects: One that builds the generator and then generates the files, one that globs the generated files and builds the rest of your build artifacts, and the superbuild project that adds both with ExternalProject_Add. By setting the dependencies correctly you can then ensure that the project that uses the generated files is configured after the generating project has been built.

However, globbing in CMake is discouraged anyway, so listing the files explicitly is the proper way to do it. If your code-generator starts generating new files then they should be added to the list manually in the same commit, as otherwise even with CONFIGURE_DEPENDS it is not guaranteed that the new files will be built when using globbing and the ExternalProject approach.

Upvotes: 1

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