[MacPorts] #60246: git 2.25.1_0 +credential_osxkeychain +diff_highlight +doc +pcre +perl5_28]: fails to install, 'unistd.h' file not found

[MacPorts]

#60246: git 2.25.1_0 +credential_osxkeychain +diff_highlight +doc +pcre +perl5_28]:
fails to install, 'unistd.h' file not found
--------------------------+--------------------
  Reporter:  jlargentaye  |      Owner:  (none)
      Type:  defect       |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:
      Port:  git          |
--------------------------+--------------------

Comment (by ryandesign):

 Replying to [ticket:60246 jlargentaye]:
 > Upgrading Git on Cataline 15.3, with a developer seed of XCode 12 &
 associated CommandLineTools.
 >
 > Of note in the logs:
 > - include paths used at compile time, {{{/opt/local/include}}} and
 {{{/usr/local/include}}}, indeed do not contain the header file unistd.h

 That is correct. It is a system header. It is not provided by MacPorts.

 We should fix the build so that it does not look in /usr/local/include.

 > - {{{DEVELOPER_DIR}}} is reported to be
 {{{DEVELOPER_DIR='/Library/Developer/CommandLineTools'}}} even though, in
 my environment, it is set to
 {{{/Applications/Xcode.app/Contents/Developer}}}, and the output of
 {{{xcode-select -p}}} is also
 {/Applications/Xcode.app/Contents/Developer}}} (and the path exists)

 That is correct. That is an intentional change as of MacPorts 2.6.0.

 > Additionally, unistd.h exists at various locations in SDKs under
 {{{/Library/Developer/CommandLineTools}}} and
 {{{/Applications/Xcode.app/Contents/Developer}}}. Specific paths can be
 provided on request.

 Does /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk exist?
 Because that's where MacPorts is going to look for system headers on your
 system. Make sure that you have command line tools ''for macOS 10.15''
 installed; it should provide that SDK.

 Note that [wiki:FAQ#prerelease we can't really help with prerelease
 software]. If you can't get it to work with Xcode 12 preview, use Xcode
 11.4 which should work.

-- 
Ticket URL: <https://trac.macports.org/ticket/60246#comment:1>
MacPorts <https://www.macports.org/>
Ports system for macOS