[GHC] #8633: template haskell mkName parses operator ^.. as a qualified operator

[GHC]

#8633: template haskell mkName parses operator ^.. as a qualified operator
-------------------------------------+------------------------------------
        Reporter:  aavogt            |            Owner:
            Type:  bug               |           Status:  closed
        Priority:  normal            |        Milestone:
       Component:  Template Haskell  |          Version:  7.6.3
      Resolution:  fixed             |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:  th/T8633          |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+------------------------------------
Changes (by simonpj):

 * status:  new => closed
 * testcase:   => th/T8633
 * resolution:   => fixed


Comment:

 Thanks for the patch. I adjusted it a bit
 {{{
 commit 21a48605d856ca334bb3a018e02255349d69a8c4
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Sat Dec 28 11:05:31 2013 +0000

     Improve mkName, so that it correctly parses the name ^..

     This fixes Trac #8633; thanks to aavogt for a first draft.


 >---------------------------------------------------------------

 21a48605d856ca334bb3a018e02255349d69a8c4
  Language/Haskell/TH/Syntax.hs |   24 ++++++++++++++++++++----
  1 file changed, 20 insertions(+), 4 deletions(-)

 diff --git a/Language/Haskell/TH/Syntax.hs b/Language/Haskell/TH/Syntax.hs
 index f3868d1..3606f9d 100644
 --- a/Language/Haskell/TH/Syntax.hs
 +++ b/Language/Haskell/TH/Syntax.hs
 @@ -24,7 +24,7 @@ import Data.IORef
  import System.IO.Unsafe        ( unsafePerformIO )
  import Control.Monad (liftM)
  import System.IO       ( hPutStrLn, stderr )
 -import Data.Char        ( isAlpha )
 +import Data.Char        ( isAlpha, isAlphaNum, isUpper )
  import Data.Word        ( Word8 )

  -----------------------------------------------------
 @@ -758,17 +758,33 @@ mkName str
    = split [] (reverse str)
    where
      split occ []        = Name (mkOccName occ) NameS
 -    split occ ('.':rev)        | not (null occ),
 -                         not (null rev), head rev /= '.'
 +    split occ ('.':rev)        | not (null occ)
 +                       , is_rev_mod_name rev
                         = Name (mkOccName occ) (NameQ (mkModName (reverse
 rev)))
         -- The 'not (null occ)' guard ensures that
         --      mkName "&." = Name "&." NameS
 -       -- The 'rev' guards ensure that
 +       -- The 'is_rev_mod' guards ensure that
         --      mkName ".&" = Name ".&" NameS
 +       --      mkName "^.." = Name "^.." NameS      -- Trac #8633
         --      mkName "Data.Bits..&" = Name ".&" (NameQ "Data.Bits")
         -- This rather bizarre case actually happened; (.&.) is in
 Data.Bits
      split occ (c:rev)   = split (c:occ) rev

 +    -- Recognises a reversed module name xA.yB.C,
 +    -- with at least one component,
 +    -- and each component looks like a module name
 +    --   (i.e. non-empty, starts with capital, all alpha)
 +    is_rev_mod_name rev_mod_str
 +      | (compt, rest) <- break (== '.') rev_mod_str
 +      , not (null compt), isUpper (last compt), all is_mod_char compt
 +      = case rest of
 +          []             -> True
 +          (_dot : rest') -> is_rev_mod_name rest'
 +      | otherwise
 +      = False
 +
 +    is_mod_char c = isAlphaNum c || c == '_' || c == '\''
 +
  -- | Only used internally
  mkNameU :: String -> Uniq -> Name
  mkNameU s (I# u) = Name (mkOccName s) (NameU u)
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8633#comment:3>
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