GCC 32bit compile on Mac

• The i386 architecture is deprecated for macOS
  

  $ gcc -m32 fib.c
  ld: warning: The i386 architecture is deprecated for macOS (remove from the Xcode build setting: ARCHS)
  ld: warning: ignoring file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib/libSystem.tbd, missing required architecture i386 in file /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib/libSystem.tbd
  Undefined symbols for architecture i386:
    "_printf", referenced from:
        _main in fib-68f6b9.o
  ld: symbol(s) not found for architecture i386
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  

• Install i386 support
  

  $ sudo rm -rf /Library/Developer/CommandLineTools
  $ xcode-select --install
  $ open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg
  

• Compile
  

  $ gcc -m32 fib.c
  ld: warning: The i386 architecture is deprecated for macOS (remove from the Xcode build setting: ARCHS)
  

  $ make CFLAGS="-m32" fib
  cc -m32    fib.c   -o fib
  ld: warning: The i386 architecture is deprecated for macOS (remove from the Xcode build setting: ARCHS)