My project was created in Xcode 3, I\'m opening it in Xcode 4 and notice the following:
From this comment here I was able to debug a similar problem with my project, it seemed to be a bad -w flag that the clang preprocessor wasn't recognizing properly. Basically, running
defaults write com.apple.dt.Xcode IDEIndexingClangInvocationLogLevel 3
in Terminal increases the verbosity of the indexer, and should help you track down issues. Run Console.app and search for IDEIndexingClang
.