As of late I see these warnings: llvm[1]: Compiling Constants.cpp for Release build /usr/include/c++/4.0.0/bits/stl_pair.h: In member function 'ConstantClass* llvm::ValueMap<ValType, TypeClass, ConstantClass, HasLargeKey>::getOrCreate(const TypeClass*, const ValType&) [with ValType = <unnamed>::ExprMapKeyType, TypeClass = llvm::Type, ConstantClass = llvm::ConstantExpr, bool HasLargeKey = false]': /usr/include/c++/4.0.0/bits/stl_pair.h:97: warning: control may reach end of non-void function 'bool<unnamed>::ExprMapKeyType::operator== (const<unnamed>::ExprMapKeyType&) const' being inlined Just a heads-up. Xcode 2.4.1. Cheers, Gabor