[GHC] #16253: Offer a shorthand for `--skip=_build/stage$n/compiler/.dependencies.mk`

[GHC]

#16253: Offer a shorthand for `--skip=_build/stage$n/compiler/.dependencies.mk`
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        Reporter:  sgraf             |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Build System      |              Version:  8.6.3
  (Hadrian)                          |
      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 NeilMitchell):

 In the past I've written a function that reads the file, and using fairly
 simplistic string matching guesses what it depends on, in the build system
 itself. It can avoid shelling out to GHC (hugely expensive on Windows,
 especially with corporate antivirus systems) and avoid running CPP.
 Generally most CPP doesn't impact which files are used, and even if it
 does, having a superset isn't a problem.

 The kind of function I've used previously is on the order of:

 {{{#!hs
 [... extract_the_module_name x ... | x <- lines src, "import "
 `isPrefixOf` x]
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16253#comment:11>
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