#15918: GHC panic from QuantifiedConstraints(?) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.2 Resolution: | Keywords: | QuantifiedConstraints Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): I propose to fix this by making `mkCastTy` use `isReflCo` rather than `isReflexiveCo`. That way it will get rid of simple reflexive casts produced by the unifier, but will not remove compound `ty ~ ty` casts. That will happen in `OptCoercion`. This is a bit more efficient (less `tcEqType`) and it comopletely avoids this horrible constraint/type choice, meaning that `substTy`, `mkCastTy` and `mkAppTy` can all be used both by Core and by the type checker. Richard: do you agree? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15918#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler