[MacPorts] #60331: Document compiler.cxx_standard

[MacPorts]

#60331: Document compiler.cxx_standard
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 Reporter:  iay          |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  guide        |    Version:
 Keywords:               |       Port:
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 Quite a few ports have Portfiles which include a setting for
 compiler.cxx_standard (usually with a value of 2011), but as far as I can
 tell this isn't documented in the guide anywhere.

 It does seem to be a useful setting to know about, particularly for ports
 which you want to have work in older releases of Mac OS X, where the
 default compiler doesn't support C++11, as it causes a different compiler
 to be used in the build process.

 It would be nice to have this documented by someone who understands the
 intended semantics.

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Ticket URL: <https://trac.macports.org/ticket/60331>
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