Annotate System.Collections.NonGeneric for nullable (dotnet/corefx#41036)

* Annotate System.Collections.NonGeneric for nullable

* Removing unnessecarry constant

* Marked CaseInsensitiveHashCodeProvider as Obsolete

* Removing NullableAttributes defintion as it was already added

* Applying feedback

* Revert "Applying feedback"

* Applying feedback

Commit migrated from https://github.com/dotnet/corefx/commit/001420e80489bf8e456d8bfb9aa22d5a02de0988

diff --git a/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.cs b/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.cs
index 2c6bd91..e51e872 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.cs
+++ b/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.cs
@@ -13,7 +13,7 @@ namespace System.Collections
         public CaseInsensitiveComparer(System.Globalization.CultureInfo culture) { }
         public static System.Collections.CaseInsensitiveComparer Default { get { throw null; } }
         public static System.Collections.CaseInsensitiveComparer DefaultInvariant { get { throw null; } }
-        public int Compare(object a, object b) { throw null; }
+        public int Compare(object? a, object? b) { throw null; }
     }
     [System.ObsoleteAttribute("Please use StringComparer instead.")]
     public partial class CaseInsensitiveHashCodeProvider : System.Collections.IHashCodeProvider
@@ -36,25 +36,25 @@ namespace System.Collections
         object System.Collections.ICollection.SyncRoot { get { throw null; } }
         bool System.Collections.IList.IsFixedSize { get { throw null; } }
         bool System.Collections.IList.IsReadOnly { get { throw null; } }
-        object System.Collections.IList.this[int index] { get { throw null; } set { } }
+        object? System.Collections.IList.this[int index] { get { throw null; } set { } }
         public void Clear() { }
         public System.Collections.IEnumerator GetEnumerator() { throw null; }
         protected virtual void OnClear() { }
         protected virtual void OnClearComplete() { }
-        protected virtual void OnInsert(int index, object value) { }
-        protected virtual void OnInsertComplete(int index, object value) { }
-        protected virtual void OnRemove(int index, object value) { }
-        protected virtual void OnRemoveComplete(int index, object value) { }
-        protected virtual void OnSet(int index, object oldValue, object newValue) { }
-        protected virtual void OnSetComplete(int index, object oldValue, object newValue) { }
+        protected virtual void OnInsert(int index, object? value) { }
+        protected virtual void OnInsertComplete(int index, object? value) { }
+        protected virtual void OnRemove(int index, object? value) { }
+        protected virtual void OnRemoveComplete(int index, object? value) { }
+        protected virtual void OnSet(int index, object? oldValue, object? newValue) { }
+        protected virtual void OnSetComplete(int index, object? oldValue, object? newValue) { }
         protected virtual void OnValidate(object value) { }
         public void RemoveAt(int index) { }
         void System.Collections.ICollection.CopyTo(System.Array array, int index) { }
-        int System.Collections.IList.Add(object value) { throw null; }
-        bool System.Collections.IList.Contains(object value) { throw null; }
-        int System.Collections.IList.IndexOf(object value) { throw null; }
-        void System.Collections.IList.Insert(int index, object value) { }
-        void System.Collections.IList.Remove(object value) { }
+        int System.Collections.IList.Add(object? value) { throw null; }
+        bool System.Collections.IList.Contains(object? value) { throw null; }
+        int System.Collections.IList.IndexOf(object? value) { throw null; }
+        void System.Collections.IList.Insert(int index, object? value) { }
+        void System.Collections.IList.Remove(object? value) { }
     }
     public abstract partial class DictionaryBase : System.Collections.ICollection, System.Collections.IDictionary, System.Collections.IEnumerable
     {
@@ -66,7 +66,7 @@ namespace System.Collections
         object System.Collections.ICollection.SyncRoot { get { throw null; } }
         bool System.Collections.IDictionary.IsFixedSize { get { throw null; } }
         bool System.Collections.IDictionary.IsReadOnly { get { throw null; } }
-        object System.Collections.IDictionary.this[object key] { get { throw null; } set { } }
+        object? System.Collections.IDictionary.this[object key] { get { throw null; } set { } }
         System.Collections.ICollection System.Collections.IDictionary.Keys { get { throw null; } }
         System.Collections.ICollection System.Collections.IDictionary.Values { get { throw null; } }
         public void Clear() { }
@@ -74,15 +74,15 @@ namespace System.Collections
         public System.Collections.IDictionaryEnumerator GetEnumerator() { throw null; }
         protected virtual void OnClear() { }
         protected virtual void OnClearComplete() { }
-        protected virtual object OnGet(object key, object currentValue) { throw null; }
-        protected virtual void OnInsert(object key, object value) { }
-        protected virtual void OnInsertComplete(object key, object value) { }
-        protected virtual void OnRemove(object key, object value) { }
-        protected virtual void OnRemoveComplete(object key, object value) { }
-        protected virtual void OnSet(object key, object oldValue, object newValue) { }
-        protected virtual void OnSetComplete(object key, object oldValue, object newValue) { }
-        protected virtual void OnValidate(object key, object value) { }
-        void System.Collections.IDictionary.Add(object key, object value) { }
+        protected virtual object? OnGet(object key, object? currentValue) { throw null; }
+        protected virtual void OnInsert(object key, object? value) { }
+        protected virtual void OnInsertComplete(object key, object? value) { }
+        protected virtual void OnRemove(object key, object? value) { }
+        protected virtual void OnRemoveComplete(object key, object? value) { }
+        protected virtual void OnSet(object key, object? oldValue, object? newValue) { }
+        protected virtual void OnSetComplete(object key, object? oldValue, object? newValue) { }
+        protected virtual void OnValidate(object key, object? value) { }
+        void System.Collections.IDictionary.Add(object key, object? value) { }
         bool System.Collections.IDictionary.Contains(object key) { throw null; }
         void System.Collections.IDictionary.Remove(object key) { }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { throw null; }
@@ -98,14 +98,14 @@ namespace System.Collections
         public virtual object SyncRoot { get { throw null; } }
         public virtual void Clear() { }
         public virtual object Clone() { throw null; }
-        public virtual bool Contains(object obj) { throw null; }
+        public virtual bool Contains(object? obj) { throw null; }
         public virtual void CopyTo(System.Array array, int index) { }
-        public virtual object Dequeue() { throw null; }
-        public virtual void Enqueue(object obj) { }
+        public virtual object? Dequeue() { throw null; }
+        public virtual void Enqueue(object? obj) { }
         public virtual System.Collections.IEnumerator GetEnumerator() { throw null; }
-        public virtual object Peek() { throw null; }
+        public virtual object? Peek() { throw null; }
         public static System.Collections.Queue Synchronized(System.Collections.Queue queue) { throw null; }
-        public virtual object[] ToArray() { throw null; }
+        public virtual object?[] ToArray() { throw null; }
         public virtual void TrimToSize() { }
     }
     public abstract partial class ReadOnlyCollectionBase : System.Collections.ICollection, System.Collections.IEnumerable
@@ -121,37 +121,37 @@ namespace System.Collections
     public partial class SortedList : System.Collections.ICollection, System.Collections.IDictionary, System.Collections.IEnumerable, System.ICloneable
     {
         public SortedList() { }
-        public SortedList(System.Collections.IComparer comparer) { }
-        public SortedList(System.Collections.IComparer comparer, int capacity) { }
+        public SortedList(System.Collections.IComparer? comparer) { }
+        public SortedList(System.Collections.IComparer? comparer, int capacity) { }
         public SortedList(System.Collections.IDictionary d) { }
-        public SortedList(System.Collections.IDictionary d, System.Collections.IComparer comparer) { }
+        public SortedList(System.Collections.IDictionary d, System.Collections.IComparer? comparer) { }
         public SortedList(int initialCapacity) { }
         public virtual int Capacity { get { throw null; } set { } }
         public virtual int Count { get { throw null; } }
         public virtual bool IsFixedSize { get { throw null; } }
         public virtual bool IsReadOnly { get { throw null; } }
         public virtual bool IsSynchronized { get { throw null; } }
-        public virtual object this[object key] { get { throw null; } set { } }
+        public virtual object? this[object key] { get { throw null; } set { } }
         public virtual System.Collections.ICollection Keys { get { throw null; } }
         public virtual object SyncRoot { get { throw null; } }
         public virtual System.Collections.ICollection Values { get { throw null; } }
-        public virtual void Add(object key, object value) { }
+        public virtual void Add(object key, object? value) { }
         public virtual void Clear() { }
         public virtual object Clone() { throw null; }
         public virtual bool Contains(object key) { throw null; }
         public virtual bool ContainsKey(object key) { throw null; }
-        public virtual bool ContainsValue(object value) { throw null; }
+        public virtual bool ContainsValue(object? value) { throw null; }
         public virtual void CopyTo(System.Array array, int arrayIndex) { }
-        public virtual object GetByIndex(int index) { throw null; }
+        public virtual object? GetByIndex(int index) { throw null; }
         public virtual System.Collections.IDictionaryEnumerator GetEnumerator() { throw null; }
         public virtual object GetKey(int index) { throw null; }
         public virtual System.Collections.IList GetKeyList() { throw null; }
         public virtual System.Collections.IList GetValueList() { throw null; }
         public virtual int IndexOfKey(object key) { throw null; }
-        public virtual int IndexOfValue(object value) { throw null; }
+        public virtual int IndexOfValue(object? value) { throw null; }
         public virtual void Remove(object key) { }
         public virtual void RemoveAt(int index) { }
-        public virtual void SetByIndex(int index, object value) { }
+        public virtual void SetByIndex(int index, object? value) { }
         public static System.Collections.SortedList Synchronized(System.Collections.SortedList list) { throw null; }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { throw null; }
         public virtual void TrimToSize() { }
@@ -166,14 +166,14 @@ namespace System.Collections
         public virtual object SyncRoot { get { throw null; } }
         public virtual void Clear() { }
         public virtual object Clone() { throw null; }
-        public virtual bool Contains(object obj) { throw null; }
+        public virtual bool Contains(object? obj) { throw null; }
         public virtual void CopyTo(System.Array array, int index) { }
         public virtual System.Collections.IEnumerator GetEnumerator() { throw null; }
-        public virtual object Peek() { throw null; }
-        public virtual object Pop() { throw null; }
-        public virtual void Push(object obj) { }
+        public virtual object? Peek() { throw null; }
+        public virtual object? Pop() { throw null; }
+        public virtual void Push(object? obj) { }
         public static System.Collections.Stack Synchronized(System.Collections.Stack stack) { throw null; }
-        public virtual object[] ToArray() { throw null; }
+        public virtual object?[] ToArray() { throw null; }
     }
 }
 namespace System.Collections.Specialized

diff --git a/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.csproj b/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.csproj
index 4ced3d5..0f04a6a 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.csproj
+++ b/src/libraries/System.Collections.NonGeneric/ref/System.Collections.NonGeneric.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <Configurations>netcoreapp-Debug;netcoreapp-Release;uap-Debug;uap-Release</Configurations>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System.Collections.NonGeneric.cs" />

diff --git a/src/libraries/System.Collections.NonGeneric/src/System.Collections.NonGeneric.csproj b/src/libraries/System.Collections.NonGeneric/src/System.Collections.NonGeneric.csproj
index ff1a5db..e238dfd 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System.Collections.NonGeneric.csproj
+++ b/src/libraries/System.Collections.NonGeneric/src/System.Collections.NonGeneric.csproj
@@ -1,9 +1,10 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <RootNamespace>System.Collections.NonGeneric</RootNamespace>
     <AssemblyName>System.Collections.NonGeneric</AssemblyName>
     <IsPartialFacadeAssembly>true</IsPartialFacadeAssembly>
     <Configurations>netcoreapp-Debug;netcoreapp-Release;uap-Windows_NT-Debug;uap-Windows_NT-Release</Configurations>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System\Collections\CaseInsensitiveComparer.cs" />

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveComparer.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveComparer.cs
index ba55861..413e056 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveComparer.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveComparer.cs
@@ -18,7 +18,7 @@ namespace System.Collections
     public class CaseInsensitiveComparer : IComparer
     {
         private readonly CompareInfo _compareInfo;
-        private static volatile CaseInsensitiveComparer s_InvariantCaseInsensitiveComparer;
+        private static volatile CaseInsensitiveComparer? s_InvariantCaseInsensitiveComparer;
 
         public CaseInsensitiveComparer()
         {
@@ -61,10 +61,10 @@ namespace System.Collections
         // If a doesn't implement IComparable and b does, -(b.CompareTo(a)) is returned.
         // Otherwise an exception is thrown.
         //
-        public int Compare(object a, object b)
+        public int Compare(object? a, object? b)
         {
-            string sa = a as string;
-            string sb = b as string;
+            string? sa = a as string;
+            string? sb = b as string;
             if (sa != null && sb != null)
                 return _compareInfo.Compare(sa, sb, CompareOptions.IgnoreCase);
             else

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveHashCodeProvider.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveHashCodeProvider.cs
index fc97729..6470d80 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveHashCodeProvider.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/CaseInsensitiveHashCodeProvider.cs
@@ -13,7 +13,7 @@ namespace System.Collections
     [Obsolete("Please use StringComparer instead.")]
     public class CaseInsensitiveHashCodeProvider : IHashCodeProvider
     {
-        private static volatile CaseInsensitiveHashCodeProvider s_invariantCaseInsensitiveHashCodeProvider = null;
+        private static volatile CaseInsensitiveHashCodeProvider? s_invariantCaseInsensitiveHashCodeProvider = null;
         private readonly CompareInfo _compareInfo;
 
         public CaseInsensitiveHashCodeProvider()
@@ -42,7 +42,7 @@ namespace System.Collections
                 throw new ArgumentNullException(nameof(obj));
             }
 
-            string s = obj as string;
+            string? s = obj as string;
             return s != null ?
                 _compareInfo.GetHashCode(s, CompareOptions.IgnoreCase) :
                 obj.GetHashCode();

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/CollectionBase.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/CollectionBase.cs
index 615d76d..8e0bfb5 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/CollectionBase.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/CollectionBase.cs
@@ -73,8 +73,8 @@ namespace System.Collections
         {
             if (index < 0 || index >= Count)
                 throw new ArgumentOutOfRangeException(nameof(index), SR.ArgumentOutOfRange_Index);
-            object temp = InnerList[index];
-            OnValidate(temp);
+            object? temp = InnerList[index];
+            OnValidate(temp!);
             OnRemove(index, temp);
             InnerList.RemoveAt(index);
             try
@@ -113,7 +113,7 @@ namespace System.Collections
             InnerList.CopyTo(array, index);
         }
 
-        object IList.this[int index]
+        object? IList.this[int index]
         {
             get
             {
@@ -125,8 +125,8 @@ namespace System.Collections
             {
                 if (index < 0 || index >= Count)
                     throw new ArgumentOutOfRangeException(nameof(index), SR.ArgumentOutOfRange_Index);
-                OnValidate(value);
-                object temp = InnerList[index];
+                OnValidate(value!);
+                object? temp = InnerList[index];
                 OnSet(index, temp, value);
                 InnerList[index] = value;
                 try
@@ -141,14 +141,14 @@ namespace System.Collections
             }
         }
 
-        bool IList.Contains(object value)
+        bool IList.Contains(object? value)
         {
             return InnerList.Contains(value);
         }
 
-        int IList.Add(object value)
+        int IList.Add(object? value)
         {
-            OnValidate(value);
+            OnValidate(value!);
             OnInsert(InnerList.Count, value);
             int index = InnerList.Add(value);
             try
@@ -164,9 +164,9 @@ namespace System.Collections
         }
 
 
-        void IList.Remove(object value)
+        void IList.Remove(object? value)
         {
-            OnValidate(value);
+            OnValidate(value!);
             int index = InnerList.IndexOf(value);
             if (index < 0) throw new ArgumentException(SR.Arg_RemoveArgNotFound);
             OnRemove(index, value);
@@ -182,16 +182,16 @@ namespace System.Collections
             }
         }
 
-        int IList.IndexOf(object value)
+        int IList.IndexOf(object? value)
         {
             return InnerList.IndexOf(value);
         }
 
-        void IList.Insert(int index, object value)
+        void IList.Insert(int index, object? value)
         {
             if (index < 0 || index > Count)
                 throw new ArgumentOutOfRangeException(nameof(index), SR.ArgumentOutOfRange_Index);
-            OnValidate(value);
+            OnValidate(value!);
             OnInsert(index, value);
             InnerList.Insert(index, value);
             try
@@ -210,11 +210,11 @@ namespace System.Collections
             return InnerList.GetEnumerator();
         }
 
-        protected virtual void OnSet(int index, object oldValue, object newValue)
+        protected virtual void OnSet(int index, object? oldValue, object? newValue)
         {
         }
 
-        protected virtual void OnInsert(int index, object value)
+        protected virtual void OnInsert(int index, object? value)
         {
         }
 
@@ -222,7 +222,7 @@ namespace System.Collections
         {
         }
 
-        protected virtual void OnRemove(int index, object value)
+        protected virtual void OnRemove(int index, object? value)
         {
         }
 
@@ -231,11 +231,11 @@ namespace System.Collections
             if (value == null) throw new ArgumentNullException(nameof(value));
         }
 
-        protected virtual void OnSetComplete(int index, object oldValue, object newValue)
+        protected virtual void OnSetComplete(int index, object? oldValue, object? newValue)
         {
         }
 
-        protected virtual void OnInsertComplete(int index, object value)
+        protected virtual void OnInsertComplete(int index, object? value)
         {
         }
 
@@ -243,7 +243,7 @@ namespace System.Collections
         {
         }
 
-        protected virtual void OnRemoveComplete(int index, object value)
+        protected virtual void OnRemoveComplete(int index, object? value)
         {
         }
     }

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/DictionaryBase.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/DictionaryBase.cs
index e2b6b5b..690ec97 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/DictionaryBase.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/DictionaryBase.cs
@@ -17,7 +17,7 @@ namespace System.Collections
     // Useful base class for typed read/write collections where items derive from object
     public abstract class DictionaryBase : IDictionary
     {
-        private Hashtable _hashtable;
+        private Hashtable? _hashtable;
 
         protected Hashtable InnerHashtable
         {
@@ -75,11 +75,11 @@ namespace System.Collections
             InnerHashtable.CopyTo(array, index);
         }
 
-        object IDictionary.this[object key]
+        object? IDictionary.this[object key]
         {
             get
             {
-                object currentValue = InnerHashtable[key];
+                object? currentValue = InnerHashtable[key];
                 OnGet(key, currentValue);
                 return currentValue;
             }
@@ -87,7 +87,7 @@ namespace System.Collections
             {
                 OnValidate(key, value);
                 bool keyExists = true;
-                object temp = InnerHashtable[key];
+                object? temp = InnerHashtable[key];
                 if (temp == null)
                 {
                     keyExists = InnerHashtable.Contains(key);
@@ -119,7 +119,7 @@ namespace System.Collections
             return InnerHashtable.Contains(key);
         }
 
-        void IDictionary.Add(object key, object value)
+        void IDictionary.Add(object key, object? value)
         {
             OnValidate(key, value);
             OnInsert(key, value);
@@ -146,7 +146,7 @@ namespace System.Collections
         {
             if (InnerHashtable.Contains(key))
             {
-                object temp = InnerHashtable[key];
+                object? temp = InnerHashtable[key];
                 OnValidate(key, temp);
                 OnRemove(key, temp);
 
@@ -173,16 +173,16 @@ namespace System.Collections
             return InnerHashtable.GetEnumerator();
         }
 
-        protected virtual object OnGet(object key, object currentValue)
+        protected virtual object? OnGet(object key, object? currentValue)
         {
             return currentValue;
         }
 
-        protected virtual void OnSet(object key, object oldValue, object newValue)
+        protected virtual void OnSet(object key, object? oldValue, object? newValue)
         {
         }
 
-        protected virtual void OnInsert(object key, object value)
+        protected virtual void OnInsert(object key, object? value)
         {
         }
 
@@ -190,19 +190,19 @@ namespace System.Collections
         {
         }
 
-        protected virtual void OnRemove(object key, object value)
+        protected virtual void OnRemove(object key, object? value)
         {
         }
 
-        protected virtual void OnValidate(object key, object value)
+        protected virtual void OnValidate(object key, object? value)
         {
         }
 
-        protected virtual void OnSetComplete(object key, object oldValue, object newValue)
+        protected virtual void OnSetComplete(object key, object? oldValue, object? newValue)
         {
         }
 
-        protected virtual void OnInsertComplete(object key, object value)
+        protected virtual void OnInsertComplete(object key, object? value)
         {
         }
 
@@ -210,7 +210,7 @@ namespace System.Collections
         {
         }
 
-        protected virtual void OnRemoveComplete(object key, object value)
+        protected virtual void OnRemoveComplete(object key, object? value)
         {
         }
     }

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/Queue.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/Queue.cs
index e156b2b..5dbb967 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/Queue.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/Queue.cs
@@ -23,7 +23,7 @@ namespace System.Collections
     [System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
     public class Queue : ICollection, ICloneable
     {
-        private object[] _array; // Do not rename (binary serialization)
+        private object?[] _array; // Do not rename (binary serialization)
         private int _head; // First valid element in the queue. Do not rename (binary serialization)
         private int _tail; // Last valid element in the queue. Do not rename (binary serialization)
         private int _size; // Number of elements. Do not rename (binary serialization)
@@ -155,7 +155,7 @@ namespace System.Collections
 
         // Adds obj to the tail of the queue.
         //
-        public virtual void Enqueue(object obj)
+        public virtual void Enqueue(object? obj)
         {
             if (_size == _array.Length)
             {
@@ -183,12 +183,12 @@ namespace System.Collections
 
         // Removes the object at the head of the queue and returns it. If the queue
         // is empty, this method simply returns null.
-        public virtual object Dequeue()
+        public virtual object? Dequeue()
         {
             if (Count == 0)
                 throw new InvalidOperationException(SR.InvalidOperation_EmptyQueue);
 
-            object removed = _array[_head];
+            object? removed = _array[_head];
             _array[_head] = null;
             _head = (_head + 1) % _array.Length;
             _size--;
@@ -199,7 +199,7 @@ namespace System.Collections
         // Returns the object at the head of the queue. The object remains in the
         // queue. If the queue is empty, this method throws an
         // InvalidOperationException.
-        public virtual object Peek()
+        public virtual object? Peek()
         {
             if (Count == 0)
                 throw new InvalidOperationException(SR.InvalidOperation_EmptyQueue);
@@ -222,8 +222,7 @@ namespace System.Collections
         // Returns true if the queue contains at least one object equal to obj.
         // Equality is determined using obj.Equals().
         //
-        // Exceptions: ArgumentNullException if obj == null.
-        public virtual bool Contains(object obj)
+        public virtual bool Contains(object? obj)
         {
             int index = _head;
             int count = _size;
@@ -235,7 +234,7 @@ namespace System.Collections
                     if (_array[index] == null)
                         return true;
                 }
-                else if (_array[index] != null && _array[index].Equals(obj))
+                else if (_array[index] != null && _array[index]!.Equals(obj))
                 {
                     return true;
                 }
@@ -245,7 +244,7 @@ namespace System.Collections
             return false;
         }
 
-        internal object GetElement(int i)
+        internal object? GetElement(int i)
         {
             return _array[(_head + i) % _array.Length];
         }
@@ -254,7 +253,7 @@ namespace System.Collections
         // objects in the Queue, or an empty array if the queue is empty.
         // The order of elements in the array is first in to last in, the same
         // order produced by successive calls to Dequeue.
-        public virtual object[] ToArray()
+        public virtual object?[] ToArray()
         {
             if (_size == 0)
                 return Array.Empty<object>();
@@ -356,7 +355,7 @@ namespace System.Collections
                 }
             }
 
-            public override bool Contains(object obj)
+            public override bool Contains(object? obj)
             {
                 lock (_root)
                 {
@@ -372,7 +371,7 @@ namespace System.Collections
                 }
             }
 
-            public override void Enqueue(object value)
+            public override void Enqueue(object? value)
             {
                 lock (_root)
                 {
@@ -380,7 +379,7 @@ namespace System.Collections
                 }
             }
 
-            public override object Dequeue()
+            public override object? Dequeue()
             {
                 lock (_root)
                 {
@@ -396,7 +395,7 @@ namespace System.Collections
                 }
             }
 
-            public override object Peek()
+            public override object? Peek()
             {
                 lock (_root)
                 {
@@ -404,7 +403,7 @@ namespace System.Collections
                 }
             }
 
-            public override object[] ToArray()
+            public override object?[] ToArray()
             {
                 lock (_root)
                 {
@@ -430,7 +429,7 @@ namespace System.Collections
             private readonly Queue _q;
             private int _index;
             private readonly int _version;
-            private object _currentElement;
+            private object? _currentElement;
 
             internal QueueEnumerator(Queue q)
             {
@@ -462,7 +461,7 @@ namespace System.Collections
                 return true;
             }
 
-            public virtual object Current
+            public virtual object? Current
             {
                 get
                 {
@@ -501,7 +500,7 @@ namespace System.Collections
             }
 
             [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
-            public object[] Items
+            public object?[] Items
             {
                 get
                 {

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/ReadOnlyCollectionBase.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/ReadOnlyCollectionBase.cs
index 097013e..2818083 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/ReadOnlyCollectionBase.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/ReadOnlyCollectionBase.cs
@@ -17,7 +17,7 @@ namespace System.Collections
     // Useful base class for typed readonly collections where items derive from object
     public abstract class ReadOnlyCollectionBase : ICollection
     {
-        private ArrayList _list;
+        private ArrayList? _list;
 
         protected ArrayList InnerList
         {

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/SortedList.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/SortedList.cs
index 776766b..dc929df 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/SortedList.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/SortedList.cs
@@ -64,12 +64,12 @@ namespace System.Collections
     public class SortedList : IDictionary, ICloneable
     {
         private object[] keys; // Do not rename (binary serialization)
-        private object[] values; // Do not rename (binary serialization)
+        private object?[] values; // Do not rename (binary serialization)
         private int _size; // Do not rename (binary serialization)
         private int version; // Do not rename (binary serialization)
         private IComparer comparer; // Do not rename (binary serialization)
-        private KeyList keyList; // Do not rename (binary serialization)
-        private ValueList valueList; // Do not rename (binary serialization)
+        private KeyList? keyList; // Do not rename (binary serialization)
+        private ValueList? valueList; // Do not rename (binary serialization)
 
         // Copy of Array.MaxArrayLength
         internal const int MaxArrayLength = 0X7FEFFFFF;
@@ -82,11 +82,6 @@ namespace System.Collections
         // all entries added to the sorted list.
         public SortedList()
         {
-            Init();
-        }
-
-        private void Init()
-        {
             keys = Array.Empty<object>();
             values = Array.Empty<object>();
             _size = 0;
@@ -120,7 +115,7 @@ namespace System.Collections
         // interface, which in that case must be implemented by the keys of all
         // entries added to the sorted list.
         //
-        public SortedList(IComparer comparer)
+        public SortedList(IComparer? comparer)
             : this()
         {
             if (comparer != null) this.comparer = comparer;
@@ -135,7 +130,7 @@ namespace System.Collections
         // the IComparable interface, which in that case must be implemented
         // by the keys of all entries added to the sorted list.
         //
-        public SortedList(IComparer comparer, int capacity)
+        public SortedList(IComparer? comparer, int capacity)
             : this(comparer)
         {
             Capacity = capacity;
@@ -160,7 +155,7 @@ namespace System.Collections
         // by the keys of all entries in the given dictionary as well as keys
         // subsequently added to the sorted list.
         //
-        public SortedList(IDictionary d, IComparer comparer)
+        public SortedList(IDictionary d, IComparer? comparer)
             : this(comparer, (d != null ? d.Count : 0))
         {
             if (d == null)
@@ -182,7 +177,7 @@ namespace System.Collections
         // Adds an entry with the given key and value to this sorted list. An
         // ArgumentException is thrown if the key is already present in the sorted list.
         //
-        public virtual void Add(object key, object value)
+        public virtual void Add(object key, object? value)
         {
             if (key == null) throw new ArgumentNullException(nameof(key), SR.ArgumentNull_Key);
 
@@ -337,7 +332,7 @@ namespace System.Collections
         // search and is substantially slower than the Contains
         // method.
         //
-        public virtual bool ContainsValue(object value)
+        public virtual bool ContainsValue(object? value)
         {
             return IndexOfValue(value) >= 0;
         }
@@ -391,7 +386,7 @@ namespace System.Collections
 
         // Returns the value of the entry at the given index.
         //
-        public virtual object GetByIndex(int index)
+        public virtual object? GetByIndex(int index)
         {
             if (index < 0 || index >= Count)
                 throw new ArgumentOutOfRangeException(nameof(index), SR.ArgumentOutOfRange_Index);
@@ -464,7 +459,7 @@ namespace System.Collections
         // Returns the value associated with the given key. If an entry with the
         // given key is not found, the returned value is null.
         //
-        public virtual object this[object key]
+        public virtual object? this[object key]
         {
             get
             {
@@ -507,13 +502,13 @@ namespace System.Collections
         // size of this sorted list. The elements of the list are compared to the
         // given value using the Object.Equals method.
         //
-        public virtual int IndexOfValue(object value)
+        public virtual int IndexOfValue(object? value)
         {
             return Array.IndexOf(values, value, 0, _size);
         }
 
         // Inserts an entry with a given key and value at a given index.
-        private void Insert(int index, object key, object value)
+        private void Insert(int index, object key, object? value)
         {
             if (_size == keys.Length) EnsureCapacity(_size + 1);
             if (index < _size)
@@ -539,7 +534,7 @@ namespace System.Collections
                 Array.Copy(keys, index + 1, keys, index, _size - index);
                 Array.Copy(values, index + 1, values, index, _size - index);
             }
-            keys[_size] = null;
+            keys[_size] = null!;
             values[_size] = null;
             version++;
         }
@@ -558,7 +553,7 @@ namespace System.Collections
         // Sets the value at an index to a given value.  The previous value of
         // the given entry is overwritten.
         //
-        public virtual void SetByIndex(int index, object value)
+        public virtual void SetByIndex(int index, object? value)
         {
             if (index < 0 || index >= Count) throw new ArgumentOutOfRangeException(nameof(index), SR.ArgumentOutOfRange_Index);
             values[index] = value;
@@ -627,7 +622,7 @@ namespace System.Collections
                 get { return true; }
             }
 
-            public override object this[object key]
+            public override object? this[object key]
             {
                 get
                 {
@@ -645,7 +640,7 @@ namespace System.Collections
                 }
             }
 
-            public override void Add(object key, object value)
+            public override void Add(object key, object? value)
             {
                 lock (_root)
                 {
@@ -690,7 +685,7 @@ namespace System.Collections
                 }
             }
 
-            public override bool ContainsValue(object key)
+            public override bool ContainsValue(object? key)
             {
                 lock (_root)
                 {
@@ -706,7 +701,7 @@ namespace System.Collections
                 }
             }
 
-            public override object GetByIndex(int index)
+            public override object? GetByIndex(int index)
             {
                 lock (_root)
                 {
@@ -757,7 +752,7 @@ namespace System.Collections
                 }
             }
 
-            public override int IndexOfValue(object value)
+            public override int IndexOfValue(object? value)
             {
                 lock (_root)
                 {
@@ -781,7 +776,7 @@ namespace System.Collections
                 }
             }
 
-            public override void SetByIndex(int index, object value)
+            public override void SetByIndex(int index, object? value)
             {
                 lock (_root)
                 {
@@ -806,8 +801,8 @@ namespace System.Collections
         private class SortedListEnumerator : IDictionaryEnumerator, ICloneable
         {
             private readonly SortedList _sortedList;
-            private object _key;
-            private object _value;
+            private object _key = null!;
+            private object? _value;
             private int _index;
             private readonly int _startIndex;        // Store for Reset.
             private readonly int _endIndex;
@@ -854,7 +849,7 @@ namespace System.Collections
                     _current = true;
                     return true;
                 }
-                _key = null;
+                _key = null!;
                 _value = null;
                 _current = false;
                 return false;
@@ -870,7 +865,7 @@ namespace System.Collections
                 }
             }
 
-            public virtual object Current
+            public virtual object? Current
             {
                 get
                 {
@@ -885,7 +880,7 @@ namespace System.Collections
                 }
             }
 
-            public virtual object Value
+            public virtual object? Value
             {
                 get
                 {
@@ -900,7 +895,7 @@ namespace System.Collections
                 if (_version != _sortedList.version) throw new InvalidOperationException(SR.InvalidOperation_EnumFailedVersion);
                 _index = _startIndex;
                 _current = false;
-                _key = null;
+                _key = null!;
                 _value = null;
             }
         }
@@ -941,7 +936,7 @@ namespace System.Collections
                 get { return sortedList.SyncRoot; }
             }
 
-            public virtual int Add(object key)
+            public virtual int Add(object? key)
             {
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
                 //            return 0; // suppress compiler warning
@@ -952,9 +947,9 @@ namespace System.Collections
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
             }
 
-            public virtual bool Contains(object key)
+            public virtual bool Contains(object? key)
             {
-                return sortedList.Contains(key);
+                return sortedList.Contains(key!);
             }
 
             public virtual void CopyTo(Array array, int arrayIndex)
@@ -963,15 +958,15 @@ namespace System.Collections
                     throw new ArgumentException(SR.Arg_RankMultiDimNotSupported, nameof(array));
 
                 // defer error checking to Array.Copy
-                Array.Copy(sortedList.keys, 0, array, arrayIndex, sortedList.Count);
+                Array.Copy(sortedList.keys, 0, array!, arrayIndex, sortedList.Count);
             }
 
-            public virtual void Insert(int index, object value)
+            public virtual void Insert(int index, object? value)
             {
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
             }
 
-            public virtual object this[int index]
+            public virtual object? this[int index]
             {
                 get
                 {
@@ -988,7 +983,7 @@ namespace System.Collections
                 return new SortedListEnumerator(sortedList, 0, sortedList.Count, SortedListEnumerator.Keys);
             }
 
-            public virtual int IndexOf(object key)
+            public virtual int IndexOf(object? key)
             {
                 if (key == null)
                     throw new ArgumentNullException(nameof(key), SR.ArgumentNull_Key);
@@ -999,7 +994,7 @@ namespace System.Collections
                 return -1;
             }
 
-            public virtual void Remove(object key)
+            public virtual void Remove(object? key)
             {
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
             }
@@ -1046,7 +1041,7 @@ namespace System.Collections
                 get { return sortedList.SyncRoot; }
             }
 
-            public virtual int Add(object key)
+            public virtual int Add(object? key)
             {
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
             }
@@ -1056,7 +1051,7 @@ namespace System.Collections
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
             }
 
-            public virtual bool Contains(object value)
+            public virtual bool Contains(object? value)
             {
                 return sortedList.ContainsValue(value);
             }
@@ -1067,15 +1062,15 @@ namespace System.Collections
                     throw new ArgumentException(SR.Arg_RankMultiDimNotSupported, nameof(array));
 
                 // defer error checking to Array.Copy
-                Array.Copy(sortedList.values, 0, array, arrayIndex, sortedList.Count);
+                Array.Copy(sortedList.values, 0, array!, arrayIndex, sortedList.Count);
             }
 
-            public virtual void Insert(int index, object value)
+            public virtual void Insert(int index, object? value)
             {
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
             }
 
-            public virtual object this[int index]
+            public virtual object? this[int index]
             {
                 get
                 {
@@ -1092,12 +1087,12 @@ namespace System.Collections
                 return new SortedListEnumerator(sortedList, 0, sortedList.Count, SortedListEnumerator.Values);
             }
 
-            public virtual int IndexOf(object value)
+            public virtual int IndexOf(object? value)
             {
                 return Array.IndexOf(sortedList.values, value, 0, sortedList.Count);
             }
 
-            public virtual void Remove(object value)
+            public virtual void Remove(object? value)
             {
                 throw new NotSupportedException(SR.NotSupported_SortedListNestedWrite);
             }

diff --git a/src/libraries/System.Collections.NonGeneric/src/System/Collections/Stack.cs b/src/libraries/System.Collections.NonGeneric/src/System/Collections/Stack.cs
index 32cd4ac..b39fe90 100644 (file)
--- a/src/libraries/System.Collections.NonGeneric/src/System/Collections/Stack.cs
+++ b/src/libraries/System.Collections.NonGeneric/src/System/Collections/Stack.cs
@@ -24,7 +24,7 @@ namespace System.Collections
     [System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
     public class Stack : ICollection, ICloneable
     {
-        private object[] _array; // Storage for stack elements. Do not rename (binary serialization)
+        private object?[] _array; // Storage for stack elements. Do not rename (binary serialization)
         private int _size; // Number of items in the stack. Do not rename (binary serialization)
         private int _version; // Used to keep enumerator in sync w/ collection. Do not rename (binary serialization)
 
@@ -96,7 +96,7 @@ namespace System.Collections
             return s;
         }
 
-        public virtual bool Contains(object obj)
+        public virtual bool Contains(object? obj)
         {
             int count = _size;
 
@@ -107,7 +107,7 @@ namespace System.Collections
                     if (_array[count] == null)
                         return true;
                 }
-                else if (_array[count] != null && _array[count].Equals(obj))
+                else if (_array[count] != null && _array[count]!.Equals(obj))
                 {
                     return true;
                 }
@@ -128,7 +128,7 @@ namespace System.Collections
                 throw new ArgumentException(SR.Argument_InvalidOffLen);
 
             int i = 0;
-            object[] objArray = array as object[];
+            object?[]? objArray = array as object[];
             if (objArray != null)
             {
                 while (i < _size)
@@ -155,7 +155,7 @@ namespace System.Collections
 
         // Returns the top object on the stack without removing it.  If the stack
         // is empty, Peek throws an InvalidOperationException.
-        public virtual object Peek()
+        public virtual object? Peek()
         {
             if (_size == 0)
                 throw new InvalidOperationException(SR.InvalidOperation_EmptyStack);
@@ -165,20 +165,20 @@ namespace System.Collections
 
         // Pops an item from the top of the stack.  If the stack is empty, Pop
         // throws an InvalidOperationException.
-        public virtual object Pop()
+        public virtual object? Pop()
         {
             if (_size == 0)
                 throw new InvalidOperationException(SR.InvalidOperation_EmptyStack);
 
             _version++;
-            object obj = _array[--_size];
+            object? obj = _array[--_size];
             _array[_size] = null;     // Free memory quicker.
             return obj;
         }
 
         // Pushes an item to the top of the stack.
         //
-        public virtual void Push(object obj)
+        public virtual void Push(object? obj)
         {
             if (_size == _array.Length)
             {
@@ -202,12 +202,12 @@ namespace System.Collections
 
 
         // Copies the Stack to an array, in the same order Pop would return the items.
-        public virtual object[] ToArray()
+        public virtual object?[] ToArray()
         {
             if (_size == 0)
                 return Array.Empty<object>();
 
-            object[] objArray = new object[_size];
+            object?[] objArray = new object[_size];
             int i = 0;
             while (i < _size)
             {
@@ -252,7 +252,7 @@ namespace System.Collections
                 }
             }
 
-            public override bool Contains(object obj)
+            public override bool Contains(object? obj)
             {
                 lock (_root)
                 {
@@ -284,7 +284,7 @@ namespace System.Collections
                 }
             }
 
-            public override void Push(object value)
+            public override void Push(object? value)
             {
                 lock (_root)
                 {
@@ -292,7 +292,7 @@ namespace System.Collections
                 }
             }
 
-            public override object Pop()
+            public override object? Pop()
             {
                 lock (_root)
                 {
@@ -308,7 +308,7 @@ namespace System.Collections
                 }
             }
 
-            public override object Peek()
+            public override object? Peek()
             {
                 lock (_root)
                 {
@@ -316,7 +316,7 @@ namespace System.Collections
                 }
             }
 
-            public override object[] ToArray()
+            public override object?[] ToArray()
             {
                 lock (_root)
                 {
@@ -330,7 +330,7 @@ namespace System.Collections
             private readonly Stack _stack;
             private int _index;
             private readonly int _version;
-            private object _currentElement;
+            private object? _currentElement;
 
             internal StackEnumerator(Stack stack)
             {
@@ -367,7 +367,7 @@ namespace System.Collections
                 return retval;
             }
 
-            public virtual object Current
+            public virtual object? Current
             {
                 get
                 {
@@ -398,7 +398,7 @@ namespace System.Collections
             }
 
             [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
-            public object[] Items
+            public object?[] Items
             {
                 get
                 {