[GHC] #11180: A program writing to a read-only stdout should not succeed

[GHC]

#11180: A program writing to a read-only stdout should not succeed
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        Reporter:  thomie            |                Owner:
            Type:  bug               |               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 Rev(s):
       Wiki Page:                    |
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Comment (by rwbarton):

 It does fail if you add a `hFlush stdout` after the `print`.

 After `main` finishes, apparently control somehow reaches `hs_exit()`,
 which calls `flushStdHandles()` which in turn calls the Haskell function
 `flushStdHandles` defined as
 {{{
 -- try to flush stdout/stderr, but don't worry if we fail
 -- (these handles might have errors, and we don't want to go into
 -- an infinite loop).
 flushStdHandles :: IO ()
 flushStdHandles = do
   hFlush stdout `catchAny` \_ -> return ()
   hFlush stderr `catchAny` \_ -> return ()
 }}}
 So, it's apparently intentional.

 I agree this is poor, though. Maybe we should swallow exceptions when
 flushing stderr, but not stdout? Or at least have the exception handler
 cause the program to exit with a different status code (if that's still
 possible at this point)?

 For what it's worth gcc does the same thing as ghc currently does (the
 error status of the `fflush` that happens after `main` finishes is
 apparently not checked).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11180#comment:2>
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