#10487: Unhelpful error from instance Generic -------------------------------------+------------------------------------- Reporter: | Owner: andreas.abel | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- That's the error you like too see, or rather not. ;( {{{ [180 of 289] Compiling Agda.TypeChecking.Serialise ( src/full/Agda/TypeChecking/Serialise.hs, dist-2.4.2.4/build/Agda/TypeChecking/Serialise.o ) src/full/Agda/TypeChecking/Serialise.hs:1:1: Duplicate instance declarations: instance GHC.Generics.Datatype Agda.TypeChecking.Serialise.D1Name -- Defined at src/full/Agda/TypeChecking/Serialise.hs:1:1 instance GHC.Generics.Datatype Agda.TypeChecking.Serialise.D1Name -- Defined at src/full/Agda/TypeChecking/Serialise.hs:1:1 src/full/Agda/TypeChecking/Serialise.hs:1:1: Duplicate instance declarations: instance GHC.Generics.Constructor Agda.TypeChecking.Serialise.C1_0Name -- Defined at src/full/Agda/TypeChecking/Serialise.hs:1:1 instance GHC.Generics.Constructor Agda.TypeChecking.Serialise.C1_0Name -- Defined at src/full/Agda/TypeChecking/Serialise.hs:1:1 }}} Problems: * no position in file * system generated names D1Name, C1_0Name * obvious bogus (same instance cannot be defined twice at same location) * leads me to suspect bug in Generics rather than in my code Reproduce: * git clone agda/agda from github, * checkout this commit https://github.com/agda/agda/commit/46823536559276807639488eae151a0e855fdb95 * and try to compile with {{{ make install-bin }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10487 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler