This avoids indirection by making calls directly to the C implementations which prevents potentials of mismatched intent or changes of calling convention of @_silgen. The added benefit is that all of the shims in this case are no longer visible symbols (anyone using them was not authorized out side of the Foundation overlay). Also the callout methods in the headers now all share similar naming shcemes for easier refactoring and searching in the style of __NS<class><action> style. The previous compiled C/Objective-C source files were built with MRR the new headers MUST be ARC by Swift import rules.
The one caveat is that certain functions MUST avoid the bridge case (since they are part of the bridging code-paths and that would incur a recursive potential) which have the types erased up to NSObject * via the macro NS_NON_BRIDGED.
The remaining @_silgen declarations are either swift functions exposed externally to the rest of Swift’s runtime or are included in NSNumber.gyb which the Foundation team has other plans for removing those @_silgen functions at a later date and Data.swift has one external function left with @_silgen which is blocked by a bug in the compiler which seems to improperly import that particular method as an inline c function.
2. Pass NSString? to thunk, not String?
3. Use proper Objective-C out parameter coding practices
4. Use correct nullability decorator in thunk for backupItemName parameter
rdar://problem/28755011
From the Swift documentation:
"If you define an optional variable without providing a default value,
the variable is automatically set to nil for you."
Addresses the following issues:
rdar://problem/25992816 -[NSUserDefaults registerDefaults] is being imported as NSUserDefaults.register(), which is confusing
rdar://problem/26291437 UserDefaults has 'setURL(forKey:)' instead of 'set(_:forKey:)'
rdar://problem/26375229 FileManager overlay has old naming
rdar://problem/26090891 NSBundle methods that are overridden in the apinotes incorrectly handle the first argument pattern
rdar://problem/26271340 struct URL initializer for fileURLWithFileSystemRepresentation is incorrectly named'
rdar://problem/26443640 XMLDTDNode.Kind conflicts with XMLNode.Kind and should be renamed to XMLDTDNode.DTDKind
rdar://problem/26500390 registerUndoWithTarget in overlay not updated for new API names
rdar://problem/26653451 NSCoder encodeDataObject is misleading
rdar://problem/26653653 NSCoder decodeObjectOfClass is redundant
rdar://problem/26653694 NSCoder.decodeTopLevelObjectForKey does not follow naming guidelines
rdar://problem/26656299 SocketNativeHandle should be a hoisted type to SocketPort
https://bugs.swift.org/browse/SR-1903
