[GHC] #8607: Invalid location reported for type constructors

[GHC]

#8607: Invalid location reported for type constructors
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       Reporter:  edsko             |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Compiler          |           Version:  7.7
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 Given

 {{{
 module Example where

 data T = MkT
 }}}

 The locations as reported in 7.4 and 7.7 are different:

 * In 7.4 the ADT is represented as a `TyData`, itself part of an
 `HsGroup`. The `TyData` contains a `Located Name`; the location of this
 name is reported correctly as 3:6. The `SrcSpan` associated with the
 `Name` itself (which represents the def site) is also reported as 3:6,
 which is dubious.

 * In 7.8 the ADT is represented as a `DataDecl` (part of ` TyClGroup`
 inside a `HsGroup`). As before, the `DataDecl`contains a `Located Name`;
 the location now however is 3:1-12, which doesn't make sense. The def site
 associated with the name itself is also 3:1-12, which ''does'' make sense.

 It seems that when the def site was fixed, it also changed the location of
 the identifier itself. These two are separate.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8607>
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