[GHC] #3696: Incorrect type inferred with -fwarn-missing-signatures and a type class

[GHC]

#3696: Incorrect type inferred with -fwarn-missing-signatures and a type class
------------------------------------------------+---------------------------
  Reporter:  spl                                |          Owner:                  
      Type:  bug                                |         Status:  closed          
  Priority:  low                                |      Milestone:  7.0.1           
 Component:  Compiler (Type checker)            |        Version:  6.10.1          
Resolution:  fixed                              |       Keywords:                  
  Testcase:  typecheck/should_compila/T3696     |      Blockedby:                  
Difficulty:                                     |             Os:  Unknown/Multiple
  Blocking:                                     |   Architecture:  Unknown/Multiple
   Failure:  Incorrect warning at compile-time  |  
------------------------------------------------+---------------------------
Changes (by simonpj):

  * status:  new => closed
  * testcase:  => typecheck/should_compila/T3696
  * resolution:  => fixed


Comment:

 Finally fixed by
 {{{
 Sun Sep 19 16:33:27 GMT Daylight Time 2010  simonpj at microsoft.com
   * Add a flag -fwarn-missing-local-sigs, and improve -fwarn-mising-
 signatures

   The new flag prints out a warning if you have a local,
   polymorphic binding that lacks a type signature. It's meant
   to help with the transition to the new typechecker, which
   discourages local let-generalisation.

   At the same time I moved the missing-signature code to TcHsSyn,
   where it takes place as part of zonking.  That way the
   types are reported after all typechecking is complete,
   thereby fixing Trac #3696.  (It's even more important for
   local bindings, which is why I made the change.)

     M ./compiler/hsSyn/HsBinds.lhs +7
     M ./compiler/main/DynFlags.hs +2
     M ./compiler/typecheck/TcBinds.lhs -39
     M ./compiler/typecheck/TcHsSyn.lhs -41 +102
     M ./compiler/typecheck/TcRnDriver.lhs -19 +26
     M ./compiler/typecheck/TcRnMonad.lhs +1
     M ./compiler/typecheck/TcRnTypes.lhs +1
 }}}
 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3696#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler