Loader for HEIC for old version of Imlib2 (i.e. for Feh). Based on libheif.
Note that new imlib2 may have heif loader built-in, hence may not require this project to open heic images.
There is a pre-built amd64 deb package on Github releases.
On Debian amd64:
apt-get install libimlib2-dev libheif-dev pkg-config build-essential
make
libheic.so
to /usr/lib/x86_64-linux-gnu/imlib2/loaders
imlib2-heic is BSD (3-clause), but it depends on libheif which is LGPL.