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 ...
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 ...