#15436: Compile-time panic, Prelude.!!: negative index -------------------------------------+------------------------------------- Reporter: pbrisbin | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.5 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by osa1): The failing `!!` call is this (in PrelRules.hs): {{{ get_con :: Type -> ConTagZ -> DataCon get_con ty tag = tyConDataCons (tyConAppTyCon ty) !! tag }}} Which is passed a negative tag in this call site probably (same file): {{{ tx_con_dtt ty (LitAlt (LitNumber LitNumInt i _)) = DataAlt (get_con ty (fromInteger i)) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15436#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler