[MacPorts] #15712: Add versions to platforms

[MacPorts]

#15712: Add versions to platforms
--------------------------+----------------------------
  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):

 In fact, the specification should express what _doesn't_ work,
 the default being that the ports works, everywhere. For example, a port
 saying

 {{{
 broken darwin < 7 # Does not have strsep (or whatever)
 }}}

 would then stop building immediately on `darwin < 7`,
 because we know it does not build on this platform.

 I believe it is simpler and better than enumerating the working cases,
 which should be the vast majority, and the default.

 For comparison, OpenBSD has a BROKEN field for that.
 For example in `audio/xmms2/Makefile`:

 {{{
 BROKEN-sparc64 = waf build goes into an infinite loop
 }}}

 "We don't build here, and this is why."
 Isn't that the purpose of this proposal as well?

-- 
Ticket URL: <https://trac.macports.org/ticket/15712#comment:38>
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