#13215: Panic: push_bang_into_newtype_arg -------------------------------------+------------------------------------- Reporter: nad | Owner: mpickering Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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): Phab:D3057 Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): No, it's not a bug. Consdier {{{ newtype T a b c = MkT (c, Maybe (a,b)) f :: T Int [x] y -> Bool f (MkT v) = ... }}} In the `ConPatOut` for `MkT` the `pat_arg_tys` will be a 3-element list, of `Int`, `[x]`, and `y`. When you call `dataConInstArgTys MkT <that list>` you'll get the singleton list back containing the type of `MkT`'s value arg: `(y, Maybe (Int,[x]))`. Now if `T` had no arguments thut {{{ newtype T = MkT (Int -> Int) }}} then of course `pat_arg_tys` will be empty, but `dataConInstArgTys` will return the singleton contianing `Int -> Int`. Does that help? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13215#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler