[GHC] #5705: getGCStats only works with +RTS -s

[GHC]

#5705: getGCStats only works with +RTS -s
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 Reporter:  tibbe             |          Owner:                  
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Component:  Runtime System  
  Version:  7.2.1             |       Keywords:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
  Failure:  None/Unknown      |       Testcase:                  
Blockedby:                    |       Blocking:                  
  Related:                    |  
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Comment(by ezyang):

 Yes, this is because the information is collected from GC statistics (note
 that you actually probably want -T, because that results in no extra
 output.)

 I'm pretty sure this is WONTFIX, because GC statistics impose nontrivial
 overhead. Something that I've been meaning to do but haven't yet is have
 the function throw an exception if stats are not available.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5705#comment:2>
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