[GHC] #7294: -fdefer-type-errors doesn't produce a warning

[GHC]

#7294: -fdefer-type-errors doesn't produce a warning
------------------------------------------+---------------------------------
  Reporter:  Feuerbach                    |          Owner:                  
      Type:  bug                          |         Status:  closed          
  Priority:  normal                       |      Milestone:                  
 Component:  Compiler (Type checker)      |        Version:  7.6.1           
Resolution:  duplicate                    |       Keywords:                  
        Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple
   Failure:  GHC accepts invalid program  |     Difficulty:  Unknown         
  Testcase:                               |      Blockedby:                  
  Blocking:                               |        Related:                  
------------------------------------------+---------------------------------
Changes (by simonpj):

  * status:  new => closed
  * difficulty:  => Unknown
  * resolution:  => duplicate


Comment:

 Yes, I'm afraid #3927 is the offending ticket.  Overlapping patterns are
 figured out *after* type checking, because it involves a sort of global
 analysis of the block of patterns.  Fixing overlapping-pattern warnings in
 the presence of GADTs requires some careful thought; a nice self-contained
 project.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7294#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler