extra commas accepted in import export lists

GHC accepts non-standard imports like

import M (,,foo,,,bar,,,)

creating problems for other Haskell implementations. Ditto for exports.

Suggest modifying this part of the grammar:

exportlist :: { [LIE RdrName] }
        :  exportlist ',' export                { $3 : $1 }
        |  exportlist ','                       { $1 }
        |  export                               { [$1]  }
        |  {- empty -}                          { [] }

to

exportlist :: { [LIE RdrName] }
        :  exportlist1 ','                      { $1 }
        |  exportlist1                          { $1 }
        |  {- empty -}                          { [] }
 
exportlist1 :: { [LIE RdrName] }
        :  exportlist1 ',' export               { $3 : $1 }
        |  export                               { [$1]  }

Trac metadata

Trac field	Value
Version	6.4.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Unknown
Architecture	Unknown