[GHC] #2360: More information in occurs check message

[GHC]

#2360: More information in occurs check message
---------------------------------+------------------------------------------
    Reporter:  ajd               |        Owner:  chak            
        Type:  feature request   |       Status:  new             
    Priority:  normal            |    Milestone:  6.12 branch     
   Component:  Compiler          |      Version:  6.8.2           
    Severity:  normal            |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
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Changes (by simonpj):

  * owner:  => chak
  * milestone:  6.10 branch => 6.12 branch

Comment:

 Quite right.  We can definitely improve this.  Older versions of GHC did
 better:
 {{{
 T2360.hs:4:10:
     Couldn't match expected type `[a]'
            against inferred type `a' (a rigid variable)
       `a' is bound by the type signature for `m' at T2360.hs:3:5
 }}}
 Note to Manuel: the equality `a ~ [a]` is deferred, and then bleated about
 in `TcTyFuns.checkOrientation`.  The latter is giving the wrong error.
 Let's fix this when the new solver is in place.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2360#comment:6>
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