[GHC] #7411: Exceptions are optimized away in certain situations

[GHC]

#7411: Exceptions are optimized away in certain situations
----------------------------------------+-----------------------------------
Reporter:  SimonHengel                  |          Owner:                                    
    Type:  bug                          |         Status:  new                               
Priority:  normal                       |      Component:  Compiler                          
 Version:  7.6.1                        |       Keywords:  seq, deepseq, evaluate, exceptions
      Os:  Linux                        |   Architecture:  x86_64 (amd64)                    
 Failure:  Incorrect result at runtime  |      Blockedby:                                    
Blocking:                               |        Related:                                    
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 The issue came up in [http://www.haskell.org/pipermail/glasgow-haskell-
 users/2012-November/023027.html this thread on glasgow-haskell-users].

 == Steps to reproduce: ==

 {{{
 -- file Foo.hs
 import Control.Exception
 import Control.DeepSeq
 main = evaluate (('a' : undefined) `deepseq` return () :: IO ())
 }}}
 {{{
 $ ghc -fforce-recomp -fpedantic-bottoms -O Foo.hs
 }}}

 === Expected result: ===
 The program should fail with:
 {{{
 Foo: Prelude.undefined
 }}}

 === Actual result: ===

 The program succeeds.

 Compiling the program with {{{-fno-state-hack}}} helps.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7411>
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