(The problems would be dramatically helped by better diagnostics about the kinds (e.g. showing which field of struct is causing non-Pod-ness) and better docume

(The problems would be dramatically helped by better diagnostics about the kinds (e.g. showing which field of struct is causing non-Pod-ness) and better documentation of them (e.g. the kinds are not listed on documentation pages for types). But that still doesn't completely help with library interaction.)