[MacPorts] #54363: ghc: needs a runtime dependency for its build compiler

[MacPorts]

#54363: ghc: needs a runtime dependency for its build compiler
-------------------------------------+------------------------
  Reporter:  mojca                   |      Owner:  neverpanic
      Type:  defect                  |     Status:  assigned
  Priority:  Normal                  |  Milestone:
 Component:  ports                   |    Version:
Resolution:                          |   Keywords:  lion
      Port:  ghc hs-bytestring-show  |
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Comment (by kencu):

 `macports-clang-4.0` builds ghc successfully on all platforms I tested
 (10.6, 10.7, 10.8, 10.11, 10.12). It should most likely be whitelisted and
 listed as both a build and runtime dependency for 10.5 to 10.8, and 10.11
 (where the system `/usr/bin/clang` does not work). This would need to be
 done in both `ghc-bootstrap` and later, after the buildbots build that, in
 `ghc`.

 I believe this would solve the issues with compiler inconsistency in ghc
 causing problems. And all these systems have `clang-4.0` installed anyway
 courtesy of the `cxx11 1.1 PortGroup`, so there is no point making them
 install `clang-3.4`.

 For some reason, even doing all that, installing something like `hs-
 bytestring-show` indicates during it's configuration stages that it looks
 for `/usr/bin/clang` anyway, as in the build log in this initial ticket,
 where it looks like it's configured to use `/usr/bin/clang` but fails when
 `clang-3.4` isn't found). This appears to be set in the `haskell 1.0`
 portgroup, but setting a compiler whitelist for clang-4.0 there does not
 seem to influence that. Anyway, it works despite that, so long as the ghc-
 bootstrap && ghc build compiler is still installed.

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Ticket URL: <https://trac.macports.org/ticket/54363#comment:15>
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