#12391: LANGUAGE CPP messes up parsing when backslash like \\ is at end of line (eol) -------------------------------------+------------------------------------- Reporter: andreas.abel | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Parser) | Keywords: CPP | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE CPP #-} import Data.List as List main = putStrLn $ "not nice" List.\\ "hot mice" }}} fails with recent ghc (I tried >= 7.8). {{{ Not in scope: ‘List.\’ }}} This problem occurred in a larger context, see https://travis-ci.org/agda/agda/jobs/144514733 It can be traced back to the use of cpp as preprocessor: {{{ $ cpp BackslashAtEOL.hs # 1 "BackslashAtEOL.hs" # 1 "<built-in>" 1 # 1 "<built-in>" 3 # 328 "<built-in>" 3 # 1 "<command line>" 1 # 1 "<built-in>" 2 # 1 "BackslashAtEOL.hs" 2 {-# LANGUAGE CPP #-} import Data.List as List main = putStrLn $ "not nice" List.\ "hot mice" }}} In contrast, cpphs would work correctly here: {{{ $ cpphs BackslashAtEOL.hs #line 1 "BackslashAtEOL.hs" {-# LANGUAGE CPP #-} import Data.List as List main = putStrLn $ "not nice" List.\\ "hot mice" }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12391> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler