[GHC] #597: Various error messages have inaccurate source locations

[GHC]

#597: Various error messages have inaccurate source locations
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  Reporter:  simonmar                    |          Owner:                  
      Type:  task                        |         Status:  new             
  Priority:  low                         |      Milestone:  _|_             
 Component:  Compiler                    |        Version:  None            
Resolution:  None                        |       Keywords:                  
Difficulty:  Moderate (less than a day)  |             Os:  Unknown/Multiple
  Testcase:                              |   Architecture:  Unknown/Multiple
   Failure:  Other                       |  
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Changes (by igloo):

  * failure:  None/Unknown => Other

Comment:

 Note that to get the full span, rather than just the start, you need to
 use the `-ferror-spans` flag. I don't know why that isn't the default.

 In 6.13:

  * 1 is fixed
  * 2 is not fixed points to the entire instance declaration
  * 3 is fixed; it points to "Eq"
  * 4 is not fixed; it points to the whole type declaration, not just "A"
  * 5 is not fixed; see `fileSrcSpan` in Parser.y.pp
  * 6 is not fixed (note that the test is now readFail016)
  * 7 is not fixed points to the entire instance declaration (same as 2?)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/597#comment:9>
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