[Foundation] Fix nullability in NSSet.

src/Foundation/NSSet.cs

@@ -32,62 +32,56 @@
 using System.Collections;
 using System.Collections.Generic;
 
-// Disable until we get around to enable + fix any issues.
-#nullable disable
+#nullable enable
 
 namespace Foundation {
 
 	public partial class NSSet : IEnumerable<NSObject> {
-		/// <param name="objs">To be added.</param>
-		///         <summary>To be added.</summary>
-		///         <remarks>To be added.</remarks>
+		/// <summary>Creates a new <see cref="NSSet" /> from an array of <see cref="NSObject" /> instances.</summary>
+		/// <param name="objs">An array of <see cref="NSObject" /> instances to include in the set.</param>
 		public NSSet (params NSObject [] objs) : this (NSArray.FromNSObjects (objs))
 		{
 		}
 
-		/// <param name="objs">To be added.</param>
-		///         <summary>To be added.</summary>
-		///         <remarks>To be added.</remarks>
+		/// <summary>Creates a new <see cref="NSSet" /> from an array of objects.</summary>
+		/// <param name="objs">An array of objects to include in the set.</param>
 		public NSSet (params object [] objs) : this (NSArray.FromObjects (objs))
 		{
 		}
 
+		/// <summary>Creates a new <see cref="NSSet" /> from an array of strings.</summary>
 		/// <param name="strings">An array of strings.</param>
-		///         <summary>Creates a set from an array of strings.</summary>
-		///         <remarks>The C# strings are stored as NSString objects in the set.</remarks>
+		/// <remarks>The C# strings are stored as <see cref="NSString" /> objects in the set.</remarks>
 		public NSSet (params string [] strings) : this (NSArray.FromStrings (strings))
 		{
 		}
 
-		/// <typeparam name="T">Strongly typed version of the array that you want to get, must be a class that derives from <see cref="Foundation.NSObject" />.</typeparam>
-		///         <summary>Returns the contents of the set as a strongly typed array.</summary>
-		///         <returns>An array of type T with the contents of the set.</returns>
-		///         <remarks>
-		///           <para>
-		/// 	    The following example shows how to get an array of UIFonts
-		/// 	  </para>
-		///           <example>
-		///             <code lang="c#"><![CDATA[
+		/// <summary>Returns the contents of the set as a strongly typed array.</summary>
+		/// <typeparam name="T">Strongly typed version of the array that you want to get, must be a class that derives from <see cref="NSObject" />.</typeparam>
+		/// <returns>An array of type <typeparamref name="T" /> with the contents of the set.</returns>
+		/// <remarks>
+		/// <para>The following example shows how to get an array of UIFonts:</para>
+		///   <example>
+		///   <code lang="c#"><![CDATA[
 		/// var myColors = new NSSet (UIColor.Red, UIColor.Blue, UIColor.Yellow);
 		/// UIColor [] asArray = myColors.ToArray<UIColor> ();
 		/// ]]></code>
-		///           </example>
-		///         </remarks>
+		///   </example>
+		/// </remarks>
 		public T [] ToArray<T> () where T : class, INativeObject
 		{
 			IntPtr nsarr = _AllObjects ();
 			return NSArray.ArrayFromHandle<T> (nsarr);
 		}
 
-		/// <typeparam name="T">To be added.</typeparam>
-		///         <param name="values">To be added.</param>
-		///         <summary>To be added.</summary>
-		///         <returns>To be added.</returns>
-		///         <remarks>To be added.</remarks>
+		/// <summary>Creates a new <see cref="NSSet" /> from an array of strongly typed values.</summary>
+		/// <typeparam name="T">The type of values in the array, must be a class that derives from <see cref="NSObject" />.</typeparam>
+		/// <param name="values">An array of strongly typed values to include in the set.</param>
+		/// <returns>A new <see cref="NSSet" /> containing the specified values.</returns>
 		public static NSSet MakeNSObjectSet<T> (T [] values) where T : class, INativeObject
 		{
 			using (var a = NSArray.FromNSObjects (values))
-				return Runtime.GetNSObject<NSSet> (_SetWithArray (a.Handle));
+				return Runtime.GetNSObject<NSSet> (_SetWithArray (a.Handle))!;
 		}
 
 		#region IEnumerable<T>
@@ -104,37 +98,48 @@ public IEnumerator<NSObject> GetEnumerator ()
 		#endregion
 
 		#region IEnumerable
-		/// <summary>Enumerate over the NSObjects in the set.</summary>
-		///         <returns>
-		///         </returns>
-		///         <remarks>This returns an enumerator that returns the NSObject objects contained in the set.  They are returned as System.Object objects.</remarks>
+		/// <summary>Enumerates over the <see cref="NSObject" /> instances in the set.</summary>
+		/// <returns>An enumerator that can be used to iterate through the set.</returns>
+		/// <remarks>This returns an enumerator that returns the <see cref="NSObject" /> objects contained in the set. They are returned as <see cref="System.Object" /> objects.</remarks>
 		IEnumerator IEnumerable.GetEnumerator ()
 		{
 			return ((IEnumerable<NSObject>) this).GetEnumerator ();
 		}
 		#endregion
 
-		public static NSSet operator + (NSSet first, NSSet second)
+		/// <summary>Adds two sets together, creating a new set that contains all elements from both sets.</summary>
+		/// <param name="first">The first set.</param>
+		/// <param name="second">The second set.</param>
+		/// <returns>A new <see cref="NSSet" /> containing all elements from both sets.</returns>
+		public static NSSet? operator + (NSSet? first, NSSet? second)
 		{
 			if (first is null)
-				return new NSSet (second);
+				return second is not null ? new NSSet (second) : null;
 			if (second is null)
 				return new NSSet (first);
 			return first.SetByAddingObjectsFromSet (second);
 		}
 
-		public static NSSet operator + (NSSet first, NSOrderedSet second)
+		/// <summary>Adds a set and an ordered set together, creating a new set that contains all elements from both.</summary>
+		/// <param name="first">The set.</param>
+		/// <param name="second">The ordered set.</param>
+		/// <returns>A new <see cref="NSSet" /> containing all elements from both the set and the ordered set.</returns>
+		public static NSSet? operator + (NSSet? first, NSOrderedSet? second)
 		{
 			if (first is null)
-				return new NSSet (second.AsSet ());
+				return second is not null ? new NSSet (second.AsSet ()) : null;
 			if (second is null)
 				return new NSSet (first);
 			var copy = new NSMutableSet (first);
 			copy.UnionSet (second.AsSet ());
 			return copy;
 		}
 
-		public static NSSet operator - (NSSet first, NSSet second)
+		/// <summary>Subtracts the elements of the second set from the first set.</summary>
+		/// <param name="first">The set to subtract from.</param>
+		/// <param name="second">The set whose elements should be removed.</param>
+		/// <returns>A new <see cref="NSSet" /> containing the elements in <paramref name="first" /> that are not in <paramref name="second" />, or <see langword="null" /> if <paramref name="first" /> is <see langword="null" />.</returns>
+		public static NSSet? operator - (NSSet? first, NSSet? second)
 		{
 			if (first is null)
 				return null;
@@ -145,7 +150,11 @@ IEnumerator IEnumerable.GetEnumerator ()
 			return copy;
 		}
 
-		public static NSSet operator - (NSSet first, NSOrderedSet second)
+		/// <summary>Subtracts the elements of an ordered set from a set.</summary>
+		/// <param name="first">The set to subtract from.</param>
+		/// <param name="second">The ordered set whose elements should be removed.</param>
+		/// <returns>A new <see cref="NSSet" /> containing the elements in <paramref name="first" /> that are not in <paramref name="second" />, or <see langword="null" /> if <paramref name="first" /> is <see langword="null" />.</returns>
+		public static NSSet? operator - (NSSet? first, NSOrderedSet? second)
 		{
 			if (first is null)
 				return null;
@@ -156,10 +165,9 @@ IEnumerator IEnumerable.GetEnumerator ()
 			return copy;
 		}
 
-		/// <param name="obj">To be added.</param>
-		///         <summary>To be added.</summary>
-		///         <returns>To be added.</returns>
-		///         <remarks>To be added.</remarks>
+		/// <summary>Determines whether the set contains the specified object.</summary>
+		/// <param name="obj">The object to locate in the set.</param>
+		/// <returns><see langword="true" /> if the set contains the specified object; otherwise, <see langword="false" />.</returns>
 		public bool Contains (object obj)
 		{
 			return Contains (NSObject.FromObject (obj));

tests/cecil-tests/Documentation.KnownFailures.txt

@@ -11993,10 +11993,6 @@ M:Foundation.NSRange.#ctor(System.IntPtr,System.IntPtr)
 M:Foundation.NSRange.Equals(Foundation.NSRange)
 M:Foundation.NSRange.Equals(System.Object)
 M:Foundation.NSRange.GetHashCode
-M:Foundation.NSSet.op_Addition(Foundation.NSSet,Foundation.NSOrderedSet)
-M:Foundation.NSSet.op_Addition(Foundation.NSSet,Foundation.NSSet)
-M:Foundation.NSSet.op_Subtraction(Foundation.NSSet,Foundation.NSOrderedSet)
-M:Foundation.NSSet.op_Subtraction(Foundation.NSSet,Foundation.NSSet)
 M:Foundation.NSSet`1.op_Addition(Foundation.NSSet{`0},Foundation.NSSet{`0})
 M:Foundation.NSSet`1.op_Subtraction(Foundation.NSSet{`0},Foundation.NSSet{`0})
 M:Foundation.NSStream.add_OnEvent(System.EventHandler{Foundation.NSStreamEventArgs})