[GHC] #8399: Of Bird tacks and non-blank blank lines

[GHC]

#8399: Of Bird tacks and non-blank blank lines
--------------------------+------------------------------------------------
       Reporter:          |             Owner:
  tinctorius              |            Status:  new
           Type:  bug     |         Milestone:
       Priority:  low     |           Version:  7.6.3
      Component:          |  Operating System:  Unknown/Multiple
  Compiler                |   Type of failure:  GHC accepts invalid program
       Keywords:          |         Test Case:
   Architecture:          |          Blocking:
  Unknown/Multiple        |
     Difficulty:          |
  Unknown                 |
     Blocked By:          |
Related Tickets:          |
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 {{{
 > main :: IO ()
 \begin{code}
 \end{code}
 > main = print "Hello world!"
 }}}

 According to the Haskell 1.2 report, code in Bird tacks must be hugged by
 blank lines (or file borders), to catch unintended use. The above should
 be _rejected_ during the unlit phase.

 However, because GHC's `unlit` thinks lines with `\begin{code}` and
 `\end{code}` are blank lines, the above is _accepted_. I believe this is
 an error.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8399>
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