[GHC] #14907: Error message: (%, %) shows up when with accidental paren

[GHC]

#14907: Error message: (%,%) shows up when with accidental paren
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 An even simpler example:

 {{{#!hs
 class (A, B)
 }}}
 {{{
 $ /opt/ghc/8.2.2/bin/ghc Bug.hs
 [1 of 1] Compiling Main             ( Bug.hs, Bug.o )

 Bug.hs:1:8: error:
     Unexpected type ‘A’
     In the class declaration for ‘GHC.Classes.(%,%)’
     A class declaration should have form
       class GHC.Classes.(%,%) a b where ...
   |
 1 | class (A, B)
   |        ^
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14907#comment:2>
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