The Apple LLVM compiler in Xcode 5.1 treats unrecognized command-line options as errors. This issue has been seen when building both Python native extensions and Ruby Gems, where some invalid compiler ...
Made the "jump" from 10.4.11 to 10.7.3 last night. First order of business was getting the Developer Tools on, so I could re-compile the CLI tools. Turns out Xcode 4.3 was just released a few days ago ...