Gentoo's Bugzilla –
Attachment 543642 Details for
Bug 616090=media-libs/openimageio-1.6.13 USE=opencv with media-libs/opencv-3.2.0 - .../work/openimageio-1.6.13/src/include/OpenImageIO/imagebufalgo.h:51:8: error: using typedef-name ‘IplImage’ after ‘struct’