Failed to build py37-pyobjc-cocoa: command execution failed

[pietvo (Pieter van Oostrum)]

py37-pyobjc-cocoa fails to build on my system. It gives an error message similar to ​ticket 59425, but the cause its slightly different. Error message:

File "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_python_py-pyobjc-cocoa/py37-pyobjc-cocoa/work/pyobjc-framework-Cocoa-5.3/pyobjc_setup.py", line 408, in Extension
:info:build     cflags.append("-DPyObjC_BUILD_RELEASE=%02d%02d"%(tuple(map(int, os.path.basename(data)[6:-4].split('.')))))
:info:build ValueError: invalid literal for int() with base 10: ''

The variable data in this statement is the SDK root, obtained by the command

/usr/bin/xcrun -sdk macosx --show-sdk-path

It appears inside the setup script this generates

/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk

i.e. without a version number to be extracted, whereas in a terminal session it generates:

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk

In the py-pyobjc port it uses get_sdk_level(self.sdk_root) to get the version numbers and this works correctly with commit a8e89f36dd6. However the corresponding commit b6d4b3fe8aa doesn't solve the problem for py-pyobjc-cocoa.