[GHC] #10744: Allow oneShot to work with unboxed types

[GHC]

#10744: Allow oneShot to work with unboxed types
-------------------------------------+-------------------------------------
        Reporter:  akio              |                   Owner:
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.2
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by akio):

 Replying to [comment:4 nomeata]:
 > Hmm, I am not sure if this is a valid use of `oneShot` if you cannot
 guarantee that the Builder will be used only once, as GHC and the runtime
 (probably) relies on the annotation to be correct, and you might get
 crashes at runtime.

 Oh, I didn't know this, thank you for pointing it out. I had hoped that it
 worked the same way as the state hack, which does not cause a crash even
 if the assumption is violated and the IO action is used multiple times.

 If this is not a valid use of `oneShot`, I don't have real uses that
 involve unlifted types. I'm happy to close this ticket.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10744#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler