[GHC] #14481: Mutually dependent modules with orphan instances causes missing symbols with single-shot compilation

[GHC]

#14481: Mutually dependent modules with orphan instances causes missing symbols
with single-shot compilation
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  8.2.1
  checker)                           |
      Resolution:  invalid           |             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 bgamari):

 Indeed this is a bug in `ghc -M`. For instance
 {{{
 $ ghc -c Instances2.hs
 $ cat Makefile
 # DO NOT DELETE: Beginning of Haskell dependencies
 Types.o : Types.hs
 Instances2.o-boot : Instances2.hs-boot
 Instances2.o-boot : Types.hi
 Main.o : Main.hs
 Main.o : Instances2.hi-boot
 Main.o : Types.hi
 Instances1.o-boot : Instances1.hs-boot
 Instances1.o-boot : Types.hi
 Instances2.o : Instances2.hs
 Instances2.o : Instances1.hi-boot
 Instances2.o : Types.hi
 Instances1.o : Instances1.hs
 Instances1.o : Instances2.hi-boot
 Instances1.o : Types.hi
 # DO NOT DELETE: End of Haskell dependencies
 }}}
 I believe GHC should have produced the following dependencies as well:
 {{{
 Instances1.o : Instances1.hi-boot
 Instances2.o : Instances2.hi-boot
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14481#comment:2>
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