#14365: Panic with (bogus?) deriving in hs-boot: newTyConEtadArity -------------------------------------+------------------------------------- Reporter: happykitten | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ $ cat A.hs module Main where import {-# SOURCE #-} B main = return () $ cat B.hs module B where data Foo a = Foo a deriving (Functor) $ cat B.hs-boot module B where data Foo a deriving (Functor) $ ghc --make A.hs [1 of 3] Compiling B[boot] ( B.hs-boot, B.o-boot ) ghc: panic! (the 'impossible' happened) (GHC version 8.2.1 for i386-unknown-linux): newTyConEtadArity Foo Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/types/TyCon.hs:2149:27 in ghc:TyCon Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14365 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler