#10743: Data declaration order matters to compiler. -------------------------------------+------------------------------------- Reporter: | Owner: thomaseding | Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Windows Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- {{{ {-# LANGUAGE GADTs #-} {-# LANGUAGE TemplateHaskell #-} import Control.Lens.TH (makeLenses) data Handle h where PlayerHandle :: Int -> Handle Player -- GHC 7.8.3 complains that NonPlayer is not in scope NonPlayerHandle :: Int -> Handle NonPlayer data Player = Player -- Deferring this until after NonPlayer is defined, resolves the compile error. -- Commenting this out also works. makeLenses ''Player data NonPlayer }}} (The exact version of 'lens' I have tried this with is 'lens-4.7' if that matters.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10743 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler