After some travails, I managed to import a C++ library (Exiv2) into a Swift package, but found that many doc comments didn't show up.
After looking more closely, I found that the doc comments didn't follow the Swift/ObjC convention of /** … */ but instead what seems to be called "QT style" with /*! … */.
QT comments apparently have a lot of marker conventions like @brief, @param and properly handling those might be out of scope, but could support for /*! … */ be added to C++ importing or is that entirely a matter for Clang to handle?