You can clone with
// ARC is compatible with iOS 4.0 upwards, but you need at least Xcode 4.2 with Clang LLVM 3.0 to compile it.
#if !defined(__clang__) || __clang_major__ < 3 || !__has_feature(objc_arc)
#error This project must be compiled with ARC (Xcode 4.2+ with LLVM 3.0 and above)
Solid. Adding this to the Nimbus arc branch.
Cool! Note that usually !__has_feature(objc_arc) should be enough, other checks were added at a time w/o arc, when i had troubles with gcc. Not sure if they make sens, I don' t believe apple will ever add ARC-support to gcc.
The recommended idiom for checking features is:
#ifndef __has_feature // Optional of course.
#define __has_feature(x) 0 // Compatibility with non-clang compilers.
i.e., there’s no need to check for Clang specifically. Having done that, one can safely use __has_feature(), e.g.