#5959: Top level splice in Template Haskell has over-ambitious lexical scope? -------------------------------------+------------------------------------- Reporter: mightybyte | Owner: Type: bug | Status: new Priority: low | Milestone: 8.0.1 Component: Template Haskell | Version: 7.5 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 Type of failure: Incorrect | (amd64) warning at compile-time | Test Case: th/T5971 Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by thomie): * component: Compiler => Template Haskell Comment: To reproduce: download Lens.hs from comment:3, then run `ghc Main.hs`, with `Main.hs` containing: {{{ {-# LANGUAGE ExistentialQuantification, TemplateHaskell #-} import Lens data App = forall b . App { _auth :: b } makeLens ''App main = return () }}} The error message should be improved, see comment:7. With ghc-7.11.20150909 I get: {{{ The exact Name ‘b_a65q’ is not in scope Probable cause: you used a unique Template Haskell name (NameU), perhaps via newName, but did not bind it If that's it, then -ddump-splices might be useful }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/5959#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler