[GHC] #16055: libffi build logic is quite spread out

[GHC]

#16055: libffi build logic is quite spread out
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        Reporter:  mpickering        |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      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 snowleopard):

 > The problem here is that the two modules are completely unrelated to
 each other.

 Note that the situation is the same across all build rules, not just
 `libffi`: the build rule and the command line flags of the corresponding
 builder(s) are specified in different modules.

 > 1. Modify the Make builder to take an additional argument which
 indicates whether to add the install flag.

 This may be consistent with so-called builder modes, e.g. see `GhcMode`,
 `ArMode`, etc. We could have `MakeMode`, one possible choice could be:

 {{{
 data MakeMode = Default | BuildGMP | InstallLibFFI
 }}}

 Not only this allows us to get red of stringly-typed builder `Make
 FilePath`, but also it makes it clearer that some invocations of Make pass
 the `install` flag.

 This seems to be more consistent with how things are currently done,
 although we could of course have exceptions if they make code clearer.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16055#comment:2>
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