I’m implementing a feature for a cmake-based FOSS project, but for NDA reasons it can only be publicly contributed when an embargo is lifted which probably won’t be for ~12 months.

Meanwhile, I need to keep up-to-date with the FOSS project so I’ve made a copy in my private repo of the file I’m editing and disabled that file from compiling in the FOSS submodule by making this small tweak:

set_source_files_properties(foo.c PROPERTIES HEADER_FILE_ONLY ON)

That works great, confirmed that my foo.c is being linked rather than the FOSS one and I can get on with software development.

Now I’d like to apply this property remotely from my private repo and get back to a clean FOSS submodule so I can pull changes. I’ve identified the target name and see the FOSS file appears in the list:

get_property(nest TARGET foss__target__name PROPERTY SOURCES)
message("FOSS sources are ${nest}")

displays FOSS sources are bar.c;blech.c;foo.c;twiddle.c

But getting and setting the HEADER_FILE_ONLY property isn’t working (bearing in mind I’ve not removed my FOSS submodule tweak yet)

get_source_file_property(cuckoo foo.c TARGET_DIRECTORY foss__target__name HEADER_FILE_ONLY)
message("foo.c bypass was set ${cuckoo}")
set_property(SOURCE foo.c TARGET_DIRECTORY foss__target__name PROPERTY HEADER_FILE_ONLY ON)

displays foo.c bypass was set NOTFOUND and the set_property doesn’t have any effect (but doesn’t fail either)

I’m using cmake 3.29.3; What am I doing wrong or is this not currently possible with cmake?