Cmake - how to inject source file into subdirectory project

Question

I have a cmake project leveraging another cmake library project, the dir looks like this:

/CMakeList.txt /main.c /.gitmodules /patch/patch.c /vendor/CMakeList.txt /vendor/vendor.c /vendor/...

In /CMakeList.txt, I used add_subdirectory(vendor) to include/link vendor library to my own project.

In /vendor/CMakeList.txt, source file is added by FILE(GLOB SRC_VEN vendor.c ...)

I want to inject /patch/patch.c into vendor library without touching /vendor directory, which is a git submodule

Is it possible to use cmake to achieve this in my root CMakeList.txt?

Thanks!

how does /vendor/CMakeList.txt really look like? Doesn't it use a wildcard in FILE(GLOB ...)? What do you mean "without touching"? Could any files be changed automatically? — m.s.
– m.s., Commented Jul 29, 2015 at 12:25
Something like target_sources(vendor_target PRIVATE "patch/patch.c") after your add_subdirectory(vendor) call? But you need to know the target's name you want to inject into (vendor_target is just a placeholder). See here for more details. — Florian
– Florian, Commented Jul 29, 2015 at 12:34
Hi @m.s. thanks for the reply, yes /vendor/CMakeLists.txt uses wildcard, i mentioned 'without touch' vendor because I can modify /vendor/CMakeLists.txt a little bit, and ignore=dirty in my .gitmodules so that the change will not be committed — jerry
– jerry, Commented Jul 29, 2015 at 13:39
Thank you, @Florian ! just tested, target_sources works like a charm — jerry
– jerry, Commented Jul 29, 2015 at 13:52

Community · Accepted Answer · 2017-05-23 11:58:19Z

Turning my comment into an answer

If you want to inject sources into an existing target you can use target_sources() (introduced with CMake version 3.1).

In your case this would look something like:

/CMakeLists.txt

... add_subdirectory(vendor) target_sources(vendor_target PRIVATE "patch/patch.c")

I put vendor_target as a placeholder. Please replace it with the real name for the target you want to inject the sources into.

For more details see e.g. here.

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