# How to specify interface link libraries of imported targets

**URL:** https://discourse.cmake.org/t/how-to-specify-interface-link-libraries-of-imported-targets/13348
**Category:** Code
**Created:** [January 8, 2025, 8:55am UTC](https://discourse.cmake.org/t/how-to-specify-interface-link-libraries-of-imported-targets/13348 "2025-01-08T08:55:15Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![ottmar-zittlau](https://discourse.cmake.org/user_avatar/discourse.cmake.org/ottmar-zittlau/32/2713_2.png) [@ottmar-zittlau](https://discourse.cmake.org/u/ottmar-zittlau)
#### Post date: [January 8, 2025, 8:55am UTC](https://discourse.cmake.org/t/how-to-specify-interface-link-libraries-of-imported-targets/13348/1 "2025-01-08T08:55:15Z")

</div>

Hi,

I’m trying to build a library with cyclic dependencies.

The whole thing involves four entities:

- two imported static libraries (libA and libB)  
both are defined in  
a “…-config.cmake” file, that is imported via `find_package`
- one static library (libC) that I define locally with `add_library(libC STATIC ...)`
- one executable that depends on `libC` via `target_link_libraries(EXE PRIVATE libC)`

```auto
# this is done in the external library's ...-config.cmake-file
add_library(libA STATIC IMPORTED)
add_library(libB STATIC IMPORTED)

# my local code
add_library(libC STATIC libC.cpp)
target_link_libraries(libC PRIVATE libA)

add_executable(EXE main.cpp)
target_link_libraries(EXE PRIVATE libC)

```

The dependencies are as follows:

- `libC` depends on `libA` as indicated above by the `target_link_libraries`-command
- `libA` depends on `libB`  
this is already accounted for in the external module by

```auto
set_target_properties(libA PROPERTIES
  INTERFACE_LINK_LIBRARIES "\$<LINK_ONLY:libB>"
)

```

- what makes things a bit tricky is, that `libB` depends both on `libA` and on `libC`

I managed to get this to work by manipulating the `INTERFACE_LINK_LIBRARIES` property of this imported target (following the discussion here: [https://gitlab.kitware.com/cmake/cmake/-/issues/17964](https://gitlab.kitware.com/cmake/cmake/-/issues/17964)):

```auto
get_target_property(LIBS libB INTERFACE_LINK_LIBRARIES)
list(APPEND LIBS libA libC)
set_target_properties(libB PROPERTIES INTERFACE_LINK_LIBRARIES "${LIBS}")

```

I find this solution a bit verbose and expected to be able to use `target_link_libraries` to achieve the same, however using

```auto
target_link_libraries(libB INTERFACE libA libC)

```

fails with error

```auto
CMake Error at src/CMakeLists.txt:33 (target_link_libraries):
Cannot specify link libraries for target "libB" which is not
built by this project.

```

I was expecting that this works, because the documentation seems to allow this command for imported targets ([https://cmake.org/cmake/help/latest/command/target\_link\_libraries.html](https://cmake.org/cmake/help/latest/command/target_link_libraries.html)): `...or as an IMPORTED library....`

I also tried `cmake_policy(SET CMP0079 NEW)`, but this didn’t change anything (my minimally required cmake version is 3.21).

In short my questions are:  
Can I somehow make `target_link_libraries` work or is there another way to specify the dependencies that is more elegant than manipulating the properties?

Thanks in advance and best regards  
oz

---

<div class="post-metadata">

### Author: ![ottmar-zittlau](https://discourse.cmake.org/user_avatar/discourse.cmake.org/ottmar-zittlau/32/2713_2.png) [@ottmar-zittlau](https://discourse.cmake.org/u/ottmar-zittlau)
#### Post date: [January 8, 2025, 9:21am UTC](https://discourse.cmake.org/t/how-to-specify-interface-link-libraries-of-imported-targets/13348/2 "2025-01-08T09:21:26Z")

</div>

In the mean time I at least figured out how to tweak the property more compactly:

```auto
set_property(TARGET libB APPEND PROPERTY INTERFACE_LINK_LIBRARIES libA libC)

```

This is very nice - still, I would like to understand why `target_link_libraries` doesn’t work.