[GHC] #16072: All dependencies of packages must be explicitly listed when defining flavour packages

[GHC]

#16072: All dependencies of packages must be explicitly listed when defining
flavour packages
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        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               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 snowleopard):

 I agree that having a more intelligent `packages` setting would be
 convenient, although I'm not sure what would be the best way forward.

 > It is also unclear to me why this function is defined recursively as
 surely when we `need` one dependency, that will in turn `need` its
 dependencies and so on.

 This function doesn't `need` anything, it's purpose is to compute the list
 of transitive dependencies of a `Context`. I believe one of the call sites
 of this function does rely on transitive dependencies being included into
 the result, although I'm afraid I don't recall right now where exactly
 this call site is. It might have something to do with package
 registration/configuration.

 How is the current recursive definition problematic, apart from
 complexity? I don't think this is immediately relevant to this issue.

 > It would be much more robust for this check to be moved to the place
 where `win32` is built.

 What do you mean? There is no one place where `win32` is built: several
 different build rules are involved in building `win32`, as any other
 package.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16072#comment:2>
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