Simon Peyton Jones authored Apr 30, 2021 and Marge Bot committed May 04, 2021

CorePrepProv is only created in CorePrep, so I thought it wouldn't be
needed in IfaceUnivCoProv.  But actually IfaceSyn is used during
pretty-printing, and we can certainly pretty-print things after
CorePrep as #19768 showed.

So the simplest thing is to represent CorePrepProv in IfaceSyn.

To improve what Lint can do I also added a boolean to CorePrepProv, to
record whether it is homogeneously kinded or not. It is introduced in
two distinct ways (see Note [Unsafe coercions] in GHC.CoreToStg.Prep),
one of which may be hetero-kinded (e.g. Int ~ Int#) beause it is
casting a divergent expression; but the other is not.  The boolean
keeps track.