[MacPorts] #60412: clang-3.7, clang-5.0, clang-6.0, clang-7.0, clang-8.0, clang-9.0, clang-devel: can't read "pythonfullpath": no such variable

[MacPorts]

#60412: clang-3.7, clang-5.0, clang-6.0, clang-7.0, clang-8.0, clang-9.0, clang-
devel: can't read "pythonfullpath": no such variable
-------------------------------------------------+-------------------------
  Reporter:  ryandesign                          |      Owner:  kencu
      Type:  defect                              |     Status:  assigned
  Priority:  Normal                              |  Milestone:
 Component:  ports                               |    Version:
Resolution:                                      |   Keywords:
      Port:  clang-3.7, clang-5.0, clang-6.0,    |
  clang-7.0, clang-8.0, clang-9.0, clang-devel   |
-------------------------------------------------+-------------------------

Comment (by ryandesign):

 It would be better not to base a decision of whether or not to add a
 depenency on whether or not a file exists. One reason is that the
 portindex files differ based on OS version but are all created on our
 buildmaster machine by faking different OS versions by passing different
 values for `os.major`. If you decide whether to add a python dependency
 based on whether a path exists, then the portindex for all OS versions
 will either add or not add the dependency, depending on whether the path
 exists on whatever OS version we happen to use on our buildmaster, rather
 than varying, as you had intended, based on the user's OS version.
 Therefore, please base the decision on `os.major` instead.
 /usr/bin/python2.7 does exist on Lion and later, so perhaps:

 {{{
 # use the system python27 if present
 if {${os.platform} eq "darwin" && ${os.major} >= 11} {
     set pythonfullpath   /usr/bin/python2.7
 } else {
     set pythonfullpath   ${prefix}/bin/python2.7
     depends_lib-append   port:python27
 }
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/60412#comment:3>
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