i386 arch error installing old scrypt gem version with OS X Mojave

Question

I\'m trying to install an old gem version for an old project after a fresh install of OS X 10.14 Mojave and XCode Command Line Tools. The gem I\'m trying to install is scryp

Answer 1

I was experiencing this exact problem.

I'm running Mojave (10.14.4) and Version 10.2 of the XCode Command Line Tools, and when running gem install scrypt -v 1.2.1, I was getting the exact same error as described above.

The solution was to install this package: /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg (as described in Can't compile C program on a Mac after upgrade to Mojave). Apparently the root of the issue was that somewhere in this process (bundler? scrypt?) there was an expectation that header files could be found in /usr/include. The latest version of XCode does not place header files in that location, but running the package places them there (as documented in the XCode release notes)