[GHC] #10320: -ddump-to-file should create empty dump files when there was nothing to dump

[GHC]

#10320: -ddump-to-file should create empty dump files when there was nothing to
dump
-------------------------------------+-------------------------------------
        Reporter:  rwbarton          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  7.10.1
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1514
       Wiki Page:                    |
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Comment (by thomie):

 Replying to [comment:10 tvv]:
 > How about to switch back to Phab:D1514 Diff 5330? It fixes the ticket's
 issue and does not introduce any side-effects like described.

 `pipeLoop` could be throwing exceptions, and dump files should be closed
 when that happens (there could be ghc api users recovering from the
 exception).

 Maybe someone else can have a look? It can't be //that// hard to fix this
 issue properly?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10320#comment:14>
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