[MacPorts] #70997: Warning: Unnecessary platforms line as darwin is the default

[MacPorts]

#70997: Warning: Unnecessary platforms line as darwin is the default
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  Reporter:  ryandesign  |      Owner:  (none)
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  base        |    Version:  2.10.1
Resolution:              |   Keywords:
      Port:              |
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Comment (by ryandesign):

 Replying to [comment:2 Dave-Allured]:
 > It also is contradictory to the guidelines in the
 [https://guide.macports.org/#development.creating-portfile port
 development chapter] of the Macports guide.

 It's not uncommon for the documentation to lag behind the code. The fact
 that the `platforms` line is now optional and does not need to be
 specified when its value is `darwin` should be added to the guide.

-- 
Ticket URL: <https://trac.macports.org/ticket/70997#comment:3>
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