[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 simonpj):

 Can you describe more explicitly "the solution you have used in the past"
 in our context?

 I think you are saying

 * Implement `ghc -scome-new-flag M.hs` which runs CPP on `M.hs` (if
 necessary), parses the result in some simple minded way, and spits out all
 of `M`'s direct imports.

 This seems to be what your `usedHeaders` thing does.

 If we could do `need (usedHeaders "M.hs")` maybe we would never need to
 use `ghc -M` at all?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16253#comment:10>
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