[GHC] #7668: Location in -fdefer-type-errors

GHC cvs-ghc at haskell.org
Wed Feb 6 19:28:49 CET 2013


#7668: Location in -fdefer-type-errors
-----------------------------+----------------------------------------------
Reporter:  monoidal          |          Owner:                  
    Type:  bug               |         Status:  new             
Priority:  normal            |      Component:  Compiler        
 Version:  7.6.2             |       Keywords:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
 Failure:  None/Unknown      |      Blockedby:                  
Blocking:                    |        Related:                  
-----------------------------+----------------------------------------------
 Consider

 {{{
 x :: Char
 x = 'x' + 1

 y :: Char
 y = 'y' + 1
 }}}

 Run `ghci -fdefer-type-errors`:

 {{{
 *Main> x
 *** Exception: G.hs:5:9:
     No instance for (Num Char) arising from a use of `+'
     In the expression: 'y' + 1
     In an equation for `y': y = 'y' + 1
 (deferred type error)
 *Main> y
 *** Exception: G.hs:5:9:
     No instance for (Num Char) arising from a use of `+'
     In the expression: 'y' + 1
     In an equation for `y': y = 'y' + 1
 (deferred type error)
 }}}

 The first exception is wrong. It seems that the missing `Num Char`
 instance is filled with the same error message in all places where the
 constraint should be supplied.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7668>
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