[MacPorts] #56996: libgcc45 @4.5.4_15: fails to upgrade on macOS 10.12.6

[MacPorts]

#56996: libgcc45 @4.5.4_15: fails to upgrade on macOS 10.12.6
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  Reporter:  mopihopi  |      Owner:  (none)
      Type:  defect    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:
Resolution:            |   Keywords:
      Port:  libgcc45  |
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Comment (by cjones051073):

 cctools defaults to using the xcode variant when it detects an Xcode
 version 9 or newer. This variant means the port simply installs wrapper
 scripts that use the Xcode supplied toolchain, instead of building its
 own. The supplied log shows that Xcode 9.2 is being used on macOS 10.12 so
 this is why the xcode variant is being activated. This is what has changed
 since June, as prior to this cctools was installing its own tool kit that
 was based on Xcode 8 (and cannot be updated until Apple open sources the
 required tools). This is why the Xcode variant came about, as using tools
 older than the Xcode compiler was causing issues in a few places.

 Do we really need libgcc45 on macOS 10.12 ? Searching the ports tree
 nothing is depending on it, so I would suggest just obsoleting this port
 on 10.12, as it is own 10.13. If a gcc compiler is required, use gcc8
 instead...

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Ticket URL: <https://trac.macports.org/ticket/56996#comment:7>
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