[GHC] #13152: Provide a mechanism to notify build system when .hi file is ready

[GHC]

#13152: Provide a mechanism to notify build system when .hi file is ready
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        Reporter:  rwbarton          |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Driver            |              Version:  8.1
      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 might not even be that hard to retrofit use of this feature into the
 existing build system, changing a rule like
 {{{
 Foo.hi : Bar.hi Baz.hi
     ghc -c Foo.hs
 }}}
 to something like
 {{{
 Foo.hi : Bar.hi Baz.hi
     ( ( ghc -c Foo.hs -finterface-file-finished=1,0,x ; \
         buildserver finished Foo.o ) & ) | read -n 1
 }}}
 and then for the `.o` files
 {{{
 Foo.o : Foo.hi
     buildserver await Foo.o
 }}}
 Here `buildserver await` is a program that will block until the
 corresponding `buildserver finished` has been run.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13152#comment:3>
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