]=])
set_target_properties(YOUR_PROJECT
PROPERTIES
INTERFACE_LINK_LIBRARIES "${YOUR_PROJECT_INTERFACE_LINK_LIBRARIES}"
)
endif()
```
but then in consuming project you will for sure encounter linking problems, as PNG symbols will be missing at the “final” linking.
Either way, hopefully you won’t need to go this way, as your problem is likely because of linking “directly” to the libraries instead of the target.
---
### Author:  [@malaterre](https://discourse.cmake.org/u/malaterre)
#### Post date: [August 13, 2024, 7:04am UTC](https://discourse.cmake.org/t/private-becomes-public-behaviour-for-static-libraries/11430/3 "2024-08-13T07:04:48Z")
> [@retif](#):
>
> It probably has to do with the way you link to PNG, because I see you are linking to its actual libraries (_`${PNG_LIBRARIES}`_) instead of its CMake target.
Indeed ! If I change the following line (\*):
`DCMTK_TARGET_LINK_LIBRARIES(dcmimage ${LIBTIFF_LIBS} ${LIBPNG_LIBS})`
into:
`DCMTK_TARGET_LINK_LIBRARIES(dcmimage ${LIBTIFF_LIBS} PNG::PNG)`
then everything works as expected (private remains private). thanks for the trick.
Just for my own curiosity where did you see it documented ? This change in behavior does not seems obvious from:
- [https://cmake.org/cmake/help/latest/module/FindPNG.html](https://cmake.org/cmake/help/latest/module/FindPNG.html)
Thanks
(\*) [git.dcmtk.org Git - dcmtk.git/blob - dcmimage/libsrc/CMakeLists.txt](https://git.dcmtk.org/?p=dcmtk.git;a=blob;f=dcmimage/libsrc/CMakeLists.txt;hb=HEAD#l28)
---
### Author:  [@retif](https://discourse.cmake.org/u/retif)
#### Post date: [August 13, 2024, 8:14am UTC](https://discourse.cmake.org/t/private-becomes-public-behaviour-for-static-libraries/11430/4 "2024-08-13T08:14:02Z")
> where did you see it documented
That isn’t something specific to the PNG’s `Find*` module, it is how [target\_link\_libraries()](https://cmake.org/cmake/help/latest/command/target_link_libraries.html) works in general - there is an explanation there about what one can link to (_targets versus libraries_).
---
### Author:  [@malaterre](https://discourse.cmake.org/u/malaterre)
#### Post date: [August 13, 2024, 9:36am UTC](https://discourse.cmake.org/t/private-becomes-public-behaviour-for-static-libraries/11430/5 "2024-08-13T09:36:18Z")
> [@malaterre](#):
>
> then everything works as expected (private remains private). thanks for the trick.
This is incorrect. `PNG::PNG` will be properly propagated (PRIVATE-becomes-PUBLIC), but the major change is that the full path is not hard-coded anymore. I can build yet another vcpkg/PNG in my third party application (same exact ABI) and then my original symptoms are now solved.
---
### Author:  [@malaterre](https://discourse.cmake.org/u/malaterre)
#### Post date: [August 13, 2024, 2:55pm UTC](https://discourse.cmake.org/t/private-becomes-public-behaviour-for-static-libraries/11430/6 "2024-08-13T14:55:12Z")
One last thing for whoever will read this.
After the above change, the following will fails:
```auto
find_package(DCMTK)
add_library(foobar DCMTK::dcmimage)
```
The error will read something like:
```auto
-- Configuring done
CMake Error at CMakeLists.txt:2 (add_library):
Target "foobar" links to target "PNG::PNG" but the target was not found.
Perhaps a find_package() call is missing for an IMPORTED target, or an
ALIAS target is missing?
-- Generating done
```
Pay attention that will be required to add the missing `find_package` not before the `add_library` call, but before the actual `find_package(DCMTK)`.
Hopefully useful for someone else.
---
### Author:  [@retif](https://discourse.cmake.org/u/retif)
#### Post date: [August 13, 2024, 3:32pm UTC](https://discourse.cmake.org/t/private-becomes-public-behaviour-for-static-libraries/11430/7 "2024-08-13T15:32:53Z")
That’s hardly any news 🙂
This is just how CMake packages/configs work by design: either project maintainer takes care of this in the package config with `find_dependency()`, or his users will have to add `find_package()` in their projects.