[MacPorts] #62474: tensorflow build fails on 10.15

[MacPorts]

#62474: tensorflow build fails on 10.15
----------------------------+--------------------------
  Reporter:  essandess      |      Owner:  emcrisostomo
      Type:  defect         |     Status:  assigned
  Priority:  Normal         |  Milestone:
 Component:  ports          |    Version:  2.6.4
Resolution:                 |   Keywords:
      Port:  py-tensorflow  |
----------------------------+--------------------------

Comment (by essandess):

 This issue isn't {{{bazel}}}-related—it's {{{xcode-select}}}-related. My
 vanilla-configured box with Xcode and CLT installed throws this error with
 {{{xcrun}}}:

 {{{
 xcode-select --reset
 xcrun --show-sdk-path
 /Applications/Xcode.app/Contents/Developer
 xcrun --show-sdk-version
 "xcrun" error: unable to lookup item 'SDKVersion' in SDK
 '/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk'
 }}}

 This is the error that {{{bazel}}} is hitting.

 To correct this:

 {{{
 sudo xcode-select --switch /Library/Developer/CommandLineTools
 xcrun --show-sdk-path
 /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk
 xcrun --show-sdk-version
 10.15.6
 }}}

 Then: {{{sudo port install py39-tensorflow}}} (and other {{{bazel}}}-based
 builds).

 But how should this be corrected from within a {{{Portfile}}}?

-- 
Ticket URL: <https://trac.macports.org/ticket/62474#comment:20>
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