Deal more correctly with orphan instances
Conal Eliott (Trac #1145) exposed a nasty flaw in the way in which orphan instances are computed, when there are functional dependencies in the class. It took me some time to figure out what was going on, and led to more refactoring. Briefly: * Elaborate comments about orphan-hood and versioning added to IfaceSyn * The is_orph field vanishes from InstEnv.Instance * Similarly ru_orph vanishes from CoreSyn.CoreRule * Orphan-hood is computed in MkIface.instanceToIfaceInst, and MkIface.coreRuleToIfaceRule Elsewhere just tidying up.
Showing with 162 additions and 98 deletions