#12921: initTc: unsolved constraints -------------------------------------+------------------------------------- Reporter: jlp | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.2.1 Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: fixed | Keywords: Operating System: MacOS X | Architecture: x86_64 | (amd64) Type of failure: Compile-time | Test Case: crash or panic | typecheck/should_fail/T12921 Blocked By: | Blocking: Related Tickets: #13106 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): gnezdo, I can confirm that your code no longer panics with GHC 8.2: {{{ $ /opt/ghc/8.2.1/bin/ghci Bug.hs GHCi, version 8.2.0.20170704: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( Bug.hs, interpreted ) Ok, 1 module loaded. λ> Log2 (2 :: GHC.TypeLits.KnownNat) <interactive>:1:1: error: Data constructor not in scope: Log2 :: t0 -> t1 <interactive>:1:12: error: • Expecting one more argument to ‘KnownNat’ Expected a type, but ‘KnownNat’ has kind ‘Nat -> Constraint’ • In an expression type signature: KnownNat In the first argument of ‘Log2’, namely ‘(2 :: KnownNat)’ In the expression: Log2 (2 :: KnownNat) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12921#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler