When should I use CMake's add_dependencies instead of target_link_libraries?

Question

I'm used to defining CMake target dependencies using the target_link_libraries() command. Recently, though, I've noticed the existence of another command, add_dependencies(). When should I use the latter rather than the former?

Note: I tried reading this question: target_link_libraries and add_dependencies - but the answers confused me. I understand I should not use both. But it's not entirely clear to me when I should use which.

Use `target_link_libraries` whenever you can. Otherwise use `add_dependencies`. It is simple. — Tsyvarev, Oct 12 '22 at 15:15
@Tsyvarev: It's simple other than the fact that sometimes the targets are not link libraries, but ok. — einpoklum, Oct 12 '22 at 17:08

score 1 · Answer 1 · answered Oct 12 '22 at 16:32

1

add_dependencies should only be used where you need to establish a dependency in the build process that would otherwise not be present.

If a you want to influence the linker options, you use target_link_libraries.

For INTERFACE targets target_link_libraries should be used, even if it doesn't have an effect on the linker options. An example would be "linking" a header only library: This usually only results in include directories being inherited; you use target_link_libraries for this nonetheless.

A notable example of using add_dependencies would be to make sure MODULE targets dynamically loaded by an executable target get built when building the executable.

answered Oct 12 '22 at 16:32

fabian

80,457
12
86
114

1

`add_dependencies` is also useful for declaring a dependency on a custom target that drives custom commands for code generation – Alex Reinking Oct 12 '22 at 16:42
@AlexReinking I consider this scenario covered with "establish a dependency in the build process". – fabian Oct 12 '22 at 16:47
I was simply suggesting another "notable example" – Alex Reinking Oct 13 '22 at 17:35

When should I use CMake's add_dependencies instead of target_link_libraries?

1 Answers1