Xcode 4.1 fatal error: stdlib modified since the precompiled header was built

Question

Building an iPhone app, using:

• Xcode 4.1
• Base SDK iOS 4.3
• Apple LLVM Compiler 2.1

I have started getting the following error

Answer 1

The xcodebuild command line tool sometimes fails with this error. This happened to me when I synched an svn workspace to an earlier build. The xcodebuild tool keeps its precompiled headers in the folder Ants mentioned:

/var/folders/... scrambled eggs .../-Caches-/com.apple.Xcode.503/SharedPrecompiledHeaders/

You have to look in the build command itself to see the actual folder name (-include /var/...), but it may be using several if you're building for different architectures (arm6, arm7, simulator, e.g.) So if you're having this problem with a command line build, just delete everything in /var/.../SharedPrecompiledHeaders.