Adding C++ support to difftastic! The change shown here is src/dynamics/b2_distance_joint.cpp in https://github.com/erincatto/box2d/commit/3d92ed4ec487b8e2aff3fc7dc58663870b17c534?branch=3d92ed4ec487b8e2aff3fc7dc58663870b17c534&diff=split and I think it compares pretty favourably with GitHub (second image).