[MacPorts] #61237: Use SPDX license identifiers

[MacPorts]

#61237: Use SPDX license identifiers
-------------------------+--------------------
  Reporter:  ryandesign  |      Owner:  (none)
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:
Resolution:              |   Keywords:
      Port:              |
-------------------------+--------------------

Comment (by ryandesign):

 Our portfile syntax already accommodates Boolean combinations of licenses.

 We might consider introducing a new option `licenses` and defining it to
 use SPDX identifiers, leaving the old `license` option using the current
 MacPorts custom license identifiers during the transitional period. This
 might make it easier to identify whether a port is using new or old
 license names, and would make it easier to write new lint rules to point
 out which ports still need their license info updated. And it finally
 fixes the long-standing obvious misnaming of the `license` option.
 port_binary_distributable.tcl could be updated to look for `licenses`
 first and fall back on `license`.

 We would want to make sure that SPDX identifiers cover 100% of our current
 license use cases, and if they do not, then we should think about what to
 do about that. For example, what would be the SPDX equivalent of our
 license identifiers "Permissive", "Restrictive",
 "Restrictive/Distributable", "Commercial", "NoMirror"?

-- 
Ticket URL: <https://trac.macports.org/ticket/61237#comment:4>
MacPorts <https://www.macports.org/>
Ports system for macOS