# How to find current INTERFACE library property whitelist?

**URL:** https://discourse.cmake.org/t/how-to-find-current-interface-library-property-whitelist/4784
**Category:** Usage
**Created:** [January 6, 2022, 1:04pm UTC](https://discourse.cmake.org/t/how-to-find-current-interface-library-property-whitelist/4784 "2022-01-06T13:04:21Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![MathiasMagnus](https://discourse.cmake.org/user_avatar/discourse.cmake.org/mathiasmagnus/32/431_2.png) [@MathiasMagnus](https://discourse.cmake.org/u/MathiasMagnus)
#### Post date: [January 6, 2022, 1:04pm UTC](https://discourse.cmake.org/t/how-to-find-current-interface-library-property-whitelist/4784/1 "2022-01-06T13:04:21Z")

</div>

I have a project where instead of meddling with global state for cleanness sake I inherit a common set of target properties via an `INTERFACE` library, including `C_EXTENSIONS` and `CXX_EXTENSIONS`, however I get the

```auto
CMake Error at CMakeLists.txt:52 (set_target_properties):
  INTERFACE_LIBRARY targets may only have whitelisted properties. The
  property "C_EXTENSIONS" is not allowed.

```

error on CMake 3.8. I would like to find out what the current whitelist of properties are on any given CMake version without having to download every version from 3.8-3.22 and give it a spin. (This question is going to arise in the future as well.) I would like to know what the impact of this facility is towards raising the minimum version requirement.

I looked inside the docs and all of the release notes, but these changes aren’t documented, however they do work with 3.22, so somewhere in between 3.8-3.22 there’s a change.

---

<div class="post-metadata">

### Author: ![jtxa](https://discourse.cmake.org/user_avatar/discourse.cmake.org/jtxa/32/1535_2.png) [@jtxa](https://discourse.cmake.org/u/jtxa)
#### Post date: [January 7, 2022, 1:54am UTC](https://discourse.cmake.org/t/how-to-find-current-interface-library-property-whitelist/4784/2 "2022-01-07T01:54:43Z")

</div>

Before CMake 3.19 almost only `INTERFACE_` prefixed properties were allowed.  
It’s documented in [https://cmake.org/cmake/help/v3.18/manual/cmake-buildsystem.7.html#interface-libraries](https://cmake.org/cmake/help/v3.18/manual/cmake-buildsystem.7.html#interface-libraries) The documentation seems to be removed completely, as there are no more restrictions.

But I don’t think this will really help you.  
I think properties like `C_EXTENSION` only apply on the target where specified and are not inherited from interfaces. Only those documented and starting with `INTERFACE_` usually will.