#13806: Invalid usage of TypeFamilies cause GHC Internal Error -------------------------------------+------------------------------------- Reporter: utdemir | Owner: (none) Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | error/warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I couldn't be able to reproduce this with a valid program, but seeing "GHC internal error" was surprising. Only the second error should be enough in this case. {{{ $ cat test.hs {-# LANGUAGE TypeFamilies #-} data Foo value = Foo (T value) class Cl t where type T mk :: t -> T main :: IO () main = undefined $ runhaskell test.hs test.hs:4:10: error: • GHC internal error: ‘T’ is not in scope during type checking, but it passed the renamer tcl_env of environment: [a10K :-> Type variable ‘value’ = value, r10F :-> ATcTyCon Foo, r10G :-> APromotionErr RecDataConPE] • In the type ‘T value’ In the definition of data constructor ‘Foo’ In the data declaration for ‘Foo’ test.hs:6:1: error: • The associated type ‘T’ mentions none of the type or kind variables of the class ‘Cl t’ • In the class declaration for ‘Cl’ $ runhaskell --version runghc 8.0.2 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13806 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler