Missing /usr/include after updating to OSX 10.14? Try this fix

Last week, I updated OSX to 10.14. After installing the XCode command line tools, I noticed that most of my projects were failing to compile. I did some poking around and found that /usr/include/ was missing.

It seems that Apple updated their software tools to look within the OSX SDK path for headers. Unfortunately, for most projects, this scheme doesn't work. Who knows what they were thinking - I doubt we're going to see a wave of projects converting to using xcode-select as a result.

To install headers at their old /usr/include location, simply run this package file:

/Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14. pkg

After installing the headers, you should be able to compile again.