[GHC] #14626: No need to enter a scrutinised value

[GHC]

#14626: No need to enter a scrutinised value
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        Reporter:  heisenbug         |                Owner:  heisenbug
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  performance
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13861            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by heisenbug):

 Replying to [comment:22 simonpj]:
 > I'm totally lost.  I believe that the `n_occ` field you are referring to
 is in the `Name` data type
 > {{{
 > data Name = Name {
 >                 n_sort :: NameSort,     -- What sort of name it is
 >                 n_occ  :: !OccName,     -- Its occurrence name
 >                 n_uniq :: {-# UNPACK #-} !Unique,
 >                 n_loc  :: !SrcSpan      -- Definition site
 >             }
 > }}}
 > I think you believe you have found some code that is allocating a `Name`
 without evaluating the `n_occ` field first.  But which code?  I see no
 `Name` allocation above?
 >
 > Also I am still perplexed about why you are trying to debug GHC itself.
 Why not run the testsuite with the stage1 compiler; and the nofib; and see
 if/when your assertions trip?  Starting with the largest Haskell program
 in the world seems... ambitious.

 Well, hubris :-)

 Seriously, it only happens with GHC!

 >
 > Or are you saying that you did all that, and not a single assertion
 tripped?
 >

 I tried a lot of things. All seemed to work.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14626#comment:25>
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