#10487: Unhelpful error from instance Generic -------------------------------------+------------------------------------- Reporter: andreas.abel | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by andreas.abel): It is also a proper bug. {{{#!hs module M where data Name = Name }}} {{{#!hs {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE StandaloneDeriving #-} module N where import GHC.Generics import qualified M data Name = Name deriving instance Generic M.Name deriving instance Generic Name }}} Error: {{{ [1 of 2] Compiling M ( M.hs, interpreted ) [2 of 2] Compiling N ( /home/abel/play/haskell/bugs/Generics/N.hs, interpreted ) /home/abel/play/haskell/bugs/Generics/N.hs:1:1: Duplicate instance declarations: instance Datatype N.D1Name -- Defined at /home/abel/play/haskell/bugs/Generics/N.hs:1:1 instance Datatype N.D1Name -- Defined at /home/abel/play/haskell/bugs/Generics/N.hs:1:1 /home/abel/play/haskell/bugs/Generics/N.hs:1:1: Duplicate instance declarations: instance Constructor N.C1_0Name -- Defined at /home/abel/play/haskell/bugs/Generics/N.hs:1:1 instance Constructor N.C1_0Name -- Defined at /home/abel/play/haskell/bugs/Generics/N.hs:1:1 Failed, modules loaded: M. }}} Qualified names are not handled properly by DeriveGeneric. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10487#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler