[MacPorts] #64572: llvm-3.4: Circular dependencies / dependency cycle

[MacPorts]

#64572: llvm-3.4: Circular dependencies / dependency cycle
-------------------------+-------------------------
  Reporter:  ryandesign  |      Owner:  (none)
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.7.1
Resolution:              |   Keywords:  snowleopard
      Port:  llvm-3.4    |
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Comment (by ryandesign):

 llvm-3.4 depends on perl5 which depends on perl5.28 which depends on xz
 and clang-3.7 both of which depend on clang-3.4 which depends on llvm-3.4.

 The perl5 dependency is declared as `bin:perl:perl5` so you might think
 that the system's perl being present would satisfy it, however the perl5
 port is also installed, so I think its dependencies are getting included
 in the calculation.

 If I remove `bin:perl:perl5` from llvm-3.4's dependencies the problem goes
 away.

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Ticket URL: <https://trac.macports.org/ticket/64572#comment:2>
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