[GHC] #959: Debugging info(?) leaks out: "Urk! Inventing strangely-kinded void TyCon"

[GHC]

#959: Debugging info(?) leaks out: "Urk! Inventing strangely-kinded void TyCon"
-------------------------------------+--------------------------------------
 Reporter:  igloo                    |          Owner:         
     Type:  bug                      |         Status:  new    
 Priority:  lowest                   |      Milestone:  _|_    
Component:  Compiler (Type checker)  |        Version:  6.6    
 Severity:  minor                    |     Resolution:         
 Keywords:                           |     Difficulty:  Unknown
 Testcase:                           |   Architecture:  Unknown
       Os:  Unknown                  |  
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Changes (by simonpj):

  * milestone:  6.6.1 => _|_
  * priority:  normal => lowest
  * severity:  normal => minor

Comment:

 The leakage is actually deliberate.

 In this program there is nothing to fix 'm' in the call to 'foo', so GHC
 makes up a fake type constructor, of kind (*->*)->*, and uses that at the
 call to foo.

 Now the trouble is that if this fake type constructor should show up in an
 interface file, GHC would not recognise the type constructor when reading
 the interface.  So I left the warning in, so that people would yell if it
 actually happened.

 This is really a bug, and I'm sure there's a way round it, but it has not
 occurred in a real program so far, so I've been postponing fixing it, and
 propose to continue to postpone.

 The relevant code is in `TcHsSyn.mkArbitraryType`

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/959>
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