macOS Big Sur Support

[JoelOsler]

Added macOS Big Sur support, as Big Sur removes access to Apple's Frameworks to the user, making os.path.isfile() fail.
os.path.isfile reads differently than direct file access.
The user doesn't have access to the Frameworks because of this -> https://www.reddit.com/r/MacOSBeta/comments/hfknpa/is_corefoundation_missing_for_everyone_on_big_sur/

[JoelOsler]

I made this edit because I am on Big Sur, and I was attempting to use my ESP8266 NodeMCU 1.0 in Arduino IDE, but it was complaining. So I did a deep dive into the python code and learned about the new changes, and added what I learned into the code.

[zsquareplusc]

Can someone confirm that this will not break support for older MacOS releases? I guess the paths to the libraries did not change, but to be sure...

[ivankravets]

@zsquareplusc how about to move it under try/except? If

iokit = ctypes.cdll.LoadLibrary(ctypes.util.find_library('IOKit'))
iokit = ctypes.cdll.LoadLibrary("/System/Library/Frameworks/IOKit.framework/Versions/Current/IOKit")
cf = ctypes.cdll.LoadLibrary(ctypes.util.find_library('CoreFoundation'))

does not work, then

iokit = ctypes.cdll.LoadLibrary("/System/Library/Frameworks/IOKit.framework/Versions/Current/IOKit")
cf = ctypes.cdll.LoadLibrary(ctypes.util.find_library('CoreFoundation'))
cf = ctypes.cdll.LoadLibrary("/System/Library/Frameworks/CoreFoundation.framework/Versions/Current/CoreFoundation")

In any case, I don't think that this PR is the best solution for this issue but it's good as a temporary workaround. We have over 1,000,000 developers for @platformio and all macOS users will be affected :(

[ivankravets]

It looks like an issue with CPython python/cpython#21241

@JoelOsler could you adapt your PR to try/except as I described above? It will work on built-in macOS Big Sur' Python 3 and with the future Python versions that have a fix.

Thanks!

[zsquareplusc]

That PR (21241) has a test that suggests that IOKit can be in one of two locations, so a hardcoded path may not work on all versions of MacOS.

[ivankravets]

Could we also iterate over

        self.assertIn(find_lib('IOKit'),
                             ('/System/Library/Frameworks/IOKit.framework/Versions/A/IOKit',
                             '/System/Library/Frameworks/IOKit.framework/IOKit'))

?

[zsquareplusc]

looking at https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPFrameworks/Concepts/FrameworkAnatomy.html i believe the short form of /path/to/x.framework/x should be sufficient and work across old and new versions of MacOS

[zsquareplusc]

beta release is available, please see #528