[GHC] #12002: Pragmas after a module declaration are ignored without warning.

1 May 2016

      #12002: Pragmas after a module declaration are ignored without warning.
-------------------------------------+-------------------------------------
           Reporter:  seanparsons    |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.10.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Other
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Normally pragmas are placed above the module declaration like so:
 {{{#!hs
 {-# LANGUAGE OverloadedStrings #-}

 module Main where
 }}}

 However if the above 2 lines are flipped around like this:
 {{{#!hs
 module Main where

 {-# LANGUAGE OverloadedStrings #-}
 }}}

 Then the behaviour seen by a user is that equivalent to the pragma not
 being present, because it would appear GHC ignores the multi-line comment
 it looks like.

 For a novice (I'm not one but it just tripped me up) this would be
 incredibly baffling (it was for me), it would be nice to see a warning for
 this at the least.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12002
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