[GHC] #11556: GHC recompiles unchanged hs-boot files

[GHC]

#11556: GHC recompiles unchanged hs-boot files
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        Reporter:  thomie            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Driver            |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  driver/recomp002/recomp002
      Blocked By:                    |             Blocking:
 Related Tickets:  #11013, #10333    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by ezyang):

 The underlying cause of this issue is, I believe, the same as #10333
 (https://ghc.haskell.org/trac/ghc/ticket/10333#comment:2). Since `A.hi` is
 not successfully compiled, we will always consider `A.hi-boot` as unstable
 (and we'll report that it is modified).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11556#comment:2>
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