6.59.2 Darwin Format Checks

Darwin targets support the CFString (or __CFString__) in the format attribute context. Declarations made with such attribution are parsed for correct syntax and format argument types. However, parsing of the format string itself is currently undefined and is not carried out by this version of the compiler.

Additionally, CFStringRefs (defined by the CoreFoundation headers) may also be used as format arguments. Note that the relevant headers are only likely to be available on Darwin (OSX) installations. On such installations, the XCode and system documentation provide descriptions of CFString, CFStringRefs and associated functions.