[GHC] #10537: Parser: commas_tup_tail duplicate SrcSpan on "Missing" value

[GHC]

#10537: Parser: commas_tup_tail duplicate SrcSpan on "Missing" value
-------------------------------------+-------------------------------------
        Reporter:  alanz             |                   Owner:  alanz
            Type:  bug               |                  Status:  patch
        Priority:  normal            |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.10.1
  (Parser)                           |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D995
-------------------------------------+-------------------------------------

Comment (by Alan Zimmerman <alan.zimm@…>):

 In [changeset:"72b21c393831b49867a296f19a2d039e48bb8dcd/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="72b21c393831b49867a296f19a2d039e48bb8dcd"
 Parser: commas_tup_tail duplicate SrcSpan on "Missing" value

 Summary:
 Parsing

     {-# LANGUAGE TupleSections #-}

     baz = (1, "hello", 6.5,,) 'a' (Just ())

 Results in the following AST fragment

     (L tests/examples/Tuple.hs:3:7-25
        (ExplicitTuple
           [ L tests/examples/Tuple.hs:3:8
               (Present
                  (L tests/examples/Tuple.hs:3:8
                     (HsOverLit
                        (OverLit
                           (HsIntegral [ '1' ] 1)
                           PlaceHolder
                           (HsLit
                              (HsString
                                 []
                                 {abstract:FastString}))
                           PlaceHolder))))
           , L tests/examples/Tuple.hs:3:11-17
               (Present
                  (L tests/examples/Tuple.hs:3:11-17
                     (HsLit
                        (HsString
                           [ '"'
                           , 'h'
                           , 'e'
                           , 'l'
                           , 'l'
                           , 'o'
                           , '"'
                           ]
                           {abstract:FastString}))))
           , L tests/examples/Tuple.hs:3:20-22
               (Present
                  (L tests/examples/Tuple.hs:3:20-22
                     (HsOverLit
                        (OverLit
                           (HsFractional
                              (FL
                                 [ '6' , '.' , '5' ]
                                 (:% 13 2)))
                           PlaceHolder
                           (HsLit
                              (HsString
                                 []
                                 {abstract:FastString}))
                           PlaceHolder))))
           , L tests/examples/Tuple.hs:3:24
               (Missing PlaceHolder)
           , L tests/examples/Tuple.hs:3:24
               (Missing PlaceHolder)
           ]

 The final `Missing PlaceHolder` has a duplicated `SrcSpan`

 Test Plan: ./validate

 Reviewers: austin, hvr, bgamari

 Reviewed By: bgamari

 Subscribers: thomie, bgamari, mpickering

 Differential Revision: https://phabricator.haskell.org/D995

 GHC Trac Issues: #10537
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10537#comment:6>
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