[MacPorts] #15712: Add versions to platforms

[MacPorts]

#15712: Add versions to platforms
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  Reporter:  raimue       |      Owner:  larryv
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:  MacPorts 2.6.0
 Component:  base         |    Version:
Resolution:               |   Keywords:
      Port:               |
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Comment (by janstary):

 I agree it is useful to be able to express some global restriction,
 such as "you need at least _this_ version of darwin to build this".

 But the proposed whitelisting and blacklisting
 sounds like the opposite of keeping it simple.

 The default should be _empty_ . If the port does not specify "platforms"
 (i.e. the Portfile does not even use the platforms keyword) it should mean
 the port has no requirements about the platform it is being built on.
 Most ports should be like that.

 The ports which do need a specfic platform would then say `darwin 8` or
 `darwin >= 10` or `darwin < 7`.
 Does anyone know about a particular port that needs to express something
 more complex
 than the simple inequalities?

 The distinction between `darwin` and `macosx` is not realistic.
 Most ports say `darwin`, and imho only do so because the `platform` field
 is required (and ignored, LOL).
 Currently, 155 ports include `macosx` among their platforms; some of those
 have `darwin macosx`.
 Does that mean all the other ports do specifically _not_ require the Apple
 Frameworks? No it doesn't.

 This is what the Guide says about platforms now, confusingly:

 > A list of the platforms on which the port has been tested. Required, but
 not interpreted in any way by the software at this time; it is purely
 informational for users. Possible values: darwin (= macosx or puredarwin),
 macosx, puredarwin, freebsd, linux, sunos, netbsd. In general, it can just
 be set to darwin. (puredarwin is an OS based on Apple's open-source Darwin
 releases without any of Apple's proprietary bits.) See also os.platform.

 So people have been putting in `darwin`, or `macosx` which is _the_same_,
 or `puredarwin` which is also the same but does not exist.

-- 
Ticket URL: <https://trac.macports.org/ticket/15712#comment:37>
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