#13467: ghc: panic! (the 'impossible' happened), initTc: unsolved constraints -------------------------------------+------------------------------------- Reporter: jhjonsson | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: duplicate | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #13106 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: new => closed * os: MacOS X => Unknown/Multiple * resolution: => duplicate * related: => #13106 Comment: Thanks for the bug report. This is a duplicate of #13106, which will be fixed in GHC 8.2. The issue arises because you're using functions that aren't defined. Here's the error message you get in GHC 8.2: {{{ [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:1:1: error: The IO action ‘main’ is not defined in module ‘Main’ | 1 | module Main (main) where | ^ Bug.hs:58:18: error: Variable not in scope: (–) :: Int -> Int -> Int | 58 | offset = ord 'A' – ord 'a' | ^ }}} So define `(–)` and `main`, and the panic should go away. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13467#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler