#12944: ghc master (8.1.20161206) panics with assertion failure with devel2 flavor and -O -------------------------------------+------------------------------------- Reporter: pacak | Owner: Type: bug | Status: closed Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.1 (CodeGen) | Resolution: fixed | 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): Phab:D2844 Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): I know exactly what is going on here, thanks to the nice example in the Description. It's a long-standing bug in the implementation of `{-# SPECIALISE instance ... #-}`. Core Lint nails it instantly. I'll look at this early next week. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12944#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler