Nullable: Uint32, (U)Int16, (U)Int64 (#23449)

* Nullable: UInt32

* (U)Int16, (U)Int64

* Make NumberFormatInfo non-nullable

5 files changed, 157 insertions, 152 deletions

diff --git a/src/System.Private.CoreLib/shared/System/Int16.cs b/src/System.Private.CoreLib/shared/System/Int16.cs
index 37e16394f5..e67225374f 100644
--- a/src/System.Private.CoreLib/shared/System/Int16.cs
+++ b/src/System.Private.CoreLib/shared/System/Int16.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -20,12 +21,12 @@ namespace System
         public const short MinValue = unchecked((short)0x8000);
 
         // Compares this object to another object, returning an integer that
-        // indicates the relationship. 
+        // indicates the relationship.
         // Returns a value less than zero if this  object
         // null is considered to be less than any instance.
         // If object is not of type Int16, this method throws an ArgumentException.
-        // 
-        public int CompareTo(object value)
+        //
+        public int CompareTo(object? value)
         {
             if (value == null)
             {
@@ -45,7 +46,7 @@ namespace System
             return m_value - value;
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (!(obj is short))
             {
@@ -72,17 +73,17 @@ namespace System
             return Number.FormatInt32(m_value, null, null);
         }
 
-        public string ToString(IFormatProvider provider)
+        public string ToString(IFormatProvider? provider)
         {
             return Number.FormatInt32(m_value, null, provider);
         }
 
-        public string ToString(string format)
+        public string ToString(string? format)
         {
             return ToString(format, null);
         }
 
-        public string ToString(string format, IFormatProvider provider)
+        public string ToString(string? format, IFormatProvider? provider)
         {
             if (m_value < 0 && format != null && format.Length > 0 && (format[0] == 'X' || format[0] == 'x'))
             {
@@ -93,7 +94,7 @@ namespace System
             return Number.FormatInt32(m_value, format, provider);
         }
 
-        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider provider = null)
+        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider? provider = null)
         {
             if (m_value < 0 && format.Length > 0 && (format[0] == 'X' || format[0] == 'x'))
             {
@@ -116,20 +117,20 @@ namespace System
             return Parse((ReadOnlySpan<char>)s, style, NumberFormatInfo.CurrentInfo);
         }
 
-        public static short Parse(string s, IFormatProvider provider)
+        public static short Parse(string s, IFormatProvider? provider)
         {
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
             return Parse((ReadOnlySpan<char>)s, NumberStyles.Integer, NumberFormatInfo.GetInstance(provider));
         }
 
-        public static short Parse(string s, NumberStyles style, IFormatProvider provider)
+        public static short Parse(string s, NumberStyles style, IFormatProvider? provider)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
             return Parse((ReadOnlySpan<char>)s, style, NumberFormatInfo.GetInstance(provider));
         }
 
-        public static short Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static short Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider? provider = null)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Parse(s, style, NumberFormatInfo.GetInstance(provider));
@@ -152,7 +153,7 @@ namespace System
             return (short)i;
         }
 
-        public static bool TryParse(string s, out short result)
+        public static bool TryParse(string? s, out short result)
         {
             if (s == null)
             {
@@ -168,7 +169,7 @@ namespace System
             return TryParse(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo, out result);
         }
 
-        public static bool TryParse(string s, NumberStyles style, IFormatProvider provider, out short result)
+        public static bool TryParse(string? s, NumberStyles style, IFormatProvider? provider, out short result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
 
@@ -181,7 +182,7 @@ namespace System
             return TryParse((ReadOnlySpan<char>)s, style, NumberFormatInfo.GetInstance(provider), out result);
         }
 
-        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider provider, out short result)
+        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider? provider, out short result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return TryParse(s, style, NumberFormatInfo.GetInstance(provider), out result);
@@ -203,7 +204,7 @@ namespace System
 
         //
         // IConvertible implementation
-        // 
+        //
 
         public TypeCode GetTypeCode()
         {
@@ -211,77 +212,77 @@ namespace System
         }
 
 
-        bool IConvertible.ToBoolean(IFormatProvider provider)
+        bool IConvertible.ToBoolean(IFormatProvider? provider)
         {
             return Convert.ToBoolean(m_value);
         }
 
-        char IConvertible.ToChar(IFormatProvider provider)
+        char IConvertible.ToChar(IFormatProvider? provider)
         {
             return Convert.ToChar(m_value);
         }
 
-        sbyte IConvertible.ToSByte(IFormatProvider provider)
+        sbyte IConvertible.ToSByte(IFormatProvider? provider)
         {
             return Convert.ToSByte(m_value);
         }
 
-        byte IConvertible.ToByte(IFormatProvider provider)
+        byte IConvertible.ToByte(IFormatProvider? provider)
         {
             return Convert.ToByte(m_value);
         }
 
-        short IConvertible.ToInt16(IFormatProvider provider)
+        short IConvertible.ToInt16(IFormatProvider? provider)
         {
             return m_value;
         }
 
-        ushort IConvertible.ToUInt16(IFormatProvider provider)
+        ushort IConvertible.ToUInt16(IFormatProvider? provider)
         {
             return Convert.ToUInt16(m_value);
         }
 
-        int IConvertible.ToInt32(IFormatProvider provider)
+        int IConvertible.ToInt32(IFormatProvider? provider)
         {
             return Convert.ToInt32(m_value);
         }
 
-        uint IConvertible.ToUInt32(IFormatProvider provider)
+        uint IConvertible.ToUInt32(IFormatProvider? provider)
         {
             return Convert.ToUInt32(m_value);
         }
 
-        long IConvertible.ToInt64(IFormatProvider provider)
+        long IConvertible.ToInt64(IFormatProvider? provider)
         {
             return Convert.ToInt64(m_value);
         }
 
-        ulong IConvertible.ToUInt64(IFormatProvider provider)
+        ulong IConvertible.ToUInt64(IFormatProvider? provider)
         {
             return Convert.ToUInt64(m_value);
         }
 
-        float IConvertible.ToSingle(IFormatProvider provider)
+        float IConvertible.ToSingle(IFormatProvider? provider)
         {
             return Convert.ToSingle(m_value);
         }
 
-        double IConvertible.ToDouble(IFormatProvider provider)
+        double IConvertible.ToDouble(IFormatProvider? provider)
         {
             return Convert.ToDouble(m_value);
         }
 
-        decimal IConvertible.ToDecimal(IFormatProvider provider)
+        decimal IConvertible.ToDecimal(IFormatProvider? provider)
         {
             return Convert.ToDecimal(m_value);
         }
 
-        DateTime IConvertible.ToDateTime(IFormatProvider provider)
+        DateTime IConvertible.ToDateTime(IFormatProvider? provider)
         {
             throw new InvalidCastException(SR.Format(SR.InvalidCast_FromTo, "Int16", "DateTime"));
         }
 
-        object IConvertible.ToType(Type type, IFormatProvider provider)
+        object IConvertible.ToType(Type type, IFormatProvider? provider)
         {
             return Convert.DefaultToType((IConvertible)this, type, provider);
         }
diff --git a/src/System.Private.CoreLib/shared/System/Int64.cs b/src/System.Private.CoreLib/shared/System/Int64.cs
index b7722fed46..303e69b26d 100644
--- a/src/System.Private.CoreLib/shared/System/Int64.cs
+++ b/src/System.Private.CoreLib/shared/System/Int64.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -20,12 +21,12 @@ namespace System
         public const long MinValue = unchecked((long)0x8000000000000000L);
 
         // Compares this object to another object, returning an integer that
-        // indicates the relationship. 
+        // indicates the relationship.
         // Returns a value less than zero if this  object
         // null is considered to be less than any instance.
         // If object is not of type Int64, this method throws an ArgumentException.
-        // 
-        public int CompareTo(object value)
+        //
+        public int CompareTo(object? value)
         {
             if (value == null)
             {
@@ -52,7 +53,7 @@ namespace System
             return 0;
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (!(obj is long))
             {
@@ -78,22 +79,22 @@ namespace System
             return Number.FormatInt64(m_value, null, null);
         }
 
-        public string ToString(IFormatProvider provider)
+        public string ToString(IFormatProvider? provider)
         {
             return Number.FormatInt64(m_value, null, provider);
         }
 
-        public string ToString(string format)
+        public string ToString(string? format)
         {
             return Number.FormatInt64(m_value, format, null);
         }
 
-        public string ToString(string format, IFormatProvider provider)
+        public string ToString(string? format, IFormatProvider? provider)
         {
             return Number.FormatInt64(m_value, format, provider);
         }
 
-        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider provider = null)
+        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider? provider = null)
         {
             return Number.TryFormatInt64(m_value, format, provider, destination, out charsWritten);
         }
@@ -111,7 +112,7 @@ namespace System
             return Number.ParseInt64(s, style, NumberFormatInfo.CurrentInfo);
         }
 
-        public static long Parse(string s, IFormatProvider provider)
+        public static long Parse(string s, IFormatProvider? provider)
         {
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
             return Number.ParseInt64(s, NumberStyles.Integer, NumberFormatInfo.GetInstance(provider));
@@ -119,23 +120,23 @@ namespace System
 
 
         // Parses a long from a String in the given style.  If
-        // a NumberFormatInfo isn't specified, the current culture's 
+        // a NumberFormatInfo isn't specified, the current culture's
         // NumberFormatInfo is assumed.
-        // 
-        public static long Parse(string s, NumberStyles style, IFormatProvider provider)
+        //
+        public static long Parse(string s, NumberStyles style, IFormatProvider? provider)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
             return Number.ParseInt64(s, style, NumberFormatInfo.GetInstance(provider));
         }
 
-        public static long Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static long Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider? provider = null)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Number.ParseInt64(s, style, NumberFormatInfo.GetInstance(provider));
         }
 
-        public static bool TryParse(string s, out long result)
+        public static bool TryParse(string? s, out long result)
         {
             if (s == null)
             {
@@ -151,7 +152,7 @@ namespace System
             return Number.TryParseInt64IntegerStyle(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo, out result) == Number.ParsingStatus.OK;
         }
 
-        public static bool TryParse(string s, NumberStyles style, IFormatProvider provider, out long result)
+        public static bool TryParse(string? s, NumberStyles style, IFormatProvider? provider, out long result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
 
@@ -164,7 +165,7 @@ namespace System
             return Number.TryParseInt64(s, style, NumberFormatInfo.GetInstance(provider), out result) == Number.ParsingStatus.OK;
         }
 
-        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider provider, out long result)
+        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider? provider, out long result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Number.TryParseInt64(s, style, NumberFormatInfo.GetInstance(provider), out result) == Number.ParsingStatus.OK;
@@ -172,84 +173,84 @@ namespace System
 
         //
         // IConvertible implementation
-        // 
+        //
 
         public TypeCode GetTypeCode()
         {
             return TypeCode.Int64;
         }
 
-        bool IConvertible.ToBoolean(IFormatProvider provider)
+        bool IConvertible.ToBoolean(IFormatProvider? provider)
         {
             return Convert.ToBoolean(m_value);
         }
 
-        char IConvertible.ToChar(IFormatProvider provider)
+        char IConvertible.ToChar(IFormatProvider? provider)
         {
             return Convert.ToChar(m_value);
         }
 
-        sbyte IConvertible.ToSByte(IFormatProvider provider)
+        sbyte IConvertible.ToSByte(IFormatProvider? provider)
         {
             return Convert.ToSByte(m_value);
         }
 
-        byte IConvertible.ToByte(IFormatProvider provider)
+        byte IConvertible.ToByte(IFormatProvider? provider)
         {
             return Convert.ToByte(m_value);
         }
 
-        short IConvertible.ToInt16(IFormatProvider provider)
+        short IConvertible.ToInt16(IFormatProvider? provider)
         {
             return Convert.ToInt16(m_value);
         }
 
-        ushort IConvertible.ToUInt16(IFormatProvider provider)
+        ushort IConvertible.ToUInt16(IFormatProvider? provider)
         {
             return Convert.ToUInt16(m_value);
         }
 
-        int IConvertible.ToInt32(IFormatProvider provider)
+        int IConvertible.ToInt32(IFormatProvider? provider)
         {
             return Convert.ToInt32(m_value);
         }
 
-        uint IConvertible.ToUInt32(IFormatProvider provider)
+        uint IConvertible.ToUInt32(IFormatProvider? provider)
         {
             return Convert.ToUInt32(m_value);
         }
 
-        long IConvertible.ToInt64(IFormatProvider provider)
+        long IConvertible.ToInt64(IFormatProvider? provider)
         {
             return m_value;
         }
 
-        ulong IConvertible.ToUInt64(IFormatProvider provider)
+        ulong IConvertible.ToUInt64(IFormatProvider? provider)
         {
             return Convert.ToUInt64(m_value);
         }
 
-        float IConvertible.ToSingle(IFormatProvider provider)
+        float IConvertible.ToSingle(IFormatProvider? provider)
         {
             return Convert.ToSingle(m_value);
         }
 
-        double IConvertible.ToDouble(IFormatProvider provider)
+        double IConvertible.ToDouble(IFormatProvider? provider)
         {
             return Convert.ToDouble(m_value);
         }
 
-        decimal IConvertible.ToDecimal(IFormatProvider provider)
+        decimal IConvertible.ToDecimal(IFormatProvider? provider)
         {
             return Convert.ToDecimal(m_value);
         }
 
-        DateTime IConvertible.ToDateTime(IFormatProvider provider)
+        DateTime IConvertible.ToDateTime(IFormatProvider? provider)
         {
             throw new InvalidCastException(SR.Format(SR.InvalidCast_FromTo, "Int64", "DateTime"));
         }
 
-        object IConvertible.ToType(Type type, IFormatProvider provider)
+        object IConvertible.ToType(Type type, IFormatProvider? provider)
         {
             return Convert.DefaultToType((IConvertible)this, type, provider);
         }
diff --git a/src/System.Private.CoreLib/shared/System/UInt16.cs b/src/System.Private.CoreLib/shared/System/UInt16.cs
index 0cce4083f0..10fd7033bb 100644
--- a/src/System.Private.CoreLib/shared/System/UInt16.cs
+++ b/src/System.Private.CoreLib/shared/System/UInt16.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -22,12 +23,12 @@ namespace System
 
 
         // Compares this object to another object, returning an integer that
-        // indicates the relationship. 
+        // indicates the relationship.
         // Returns a value less than zero if this  object
         // null is considered to be less than any instance.
         // If object is not of type UInt16, this method throws an ArgumentException.
-        // 
-        public int CompareTo(object value)
+        //
+        public int CompareTo(object? value)
         {
             if (value == null)
             {
@@ -45,7 +46,7 @@ namespace System
             return ((int)m_value - (int)value);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (!(obj is ushort))
             {
@@ -72,23 +73,23 @@ namespace System
             return Number.FormatUInt32(m_value, null, null);
         }
 
-        public string ToString(IFormatProvider provider)
+        public string ToString(IFormatProvider? provider)
         {
             return Number.FormatUInt32(m_value, null, provider);
         }
 
 
-        public string ToString(string format)
+        public string ToString(string? format)
         {
             return Number.FormatUInt32(m_value, format, null);
         }
 
-        public string ToString(string format, IFormatProvider provider)
+        public string ToString(string? format, IFormatProvider? provider)
         {
             return Number.FormatUInt32(m_value, format, provider);
         }
 
-        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider provider = null)
+        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider? provider = null)
         {
             return Number.TryFormatUInt32(m_value, format, provider, destination, out charsWritten);
         }
@@ -110,14 +111,14 @@ namespace System
 
 
         [CLSCompliant(false)]
-        public static ushort Parse(string s, IFormatProvider provider)
+        public static ushort Parse(string s, IFormatProvider? provider)
         {
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
             return Parse((ReadOnlySpan<char>)s, NumberStyles.Integer, NumberFormatInfo.GetInstance(provider));
         }
 
         [CLSCompliant(false)]
-        public static ushort Parse(string s, NumberStyles style, IFormatProvider provider)
+        public static ushort Parse(string s, NumberStyles style, IFormatProvider? provider)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
@@ -125,7 +126,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static ushort Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static ushort Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider? provider = null)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Parse(s, style, NumberFormatInfo.GetInstance(provider));
@@ -144,7 +145,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(string s, out ushort result)
+        public static bool TryParse(string? s, out ushort result)
         {
             if (s == null)
             {
@@ -162,7 +163,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(string s, NumberStyles style, IFormatProvider provider, out ushort result)
+        public static bool TryParse(string? s, NumberStyles style, IFormatProvider? provider, out ushort result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
 
@@ -176,7 +177,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider provider, out ushort result)
+        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider? provider, out ushort result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return TryParse(s, style, NumberFormatInfo.GetInstance(provider), out result);
@@ -196,84 +197,84 @@ namespace System
 
         //
         // IConvertible implementation
-        // 
+        //
 
         public TypeCode GetTypeCode()
         {
             return TypeCode.UInt16;
         }
 
-        bool IConvertible.ToBoolean(IFormatProvider provider)
+        bool IConvertible.ToBoolean(IFormatProvider? provider)
         {
             return Convert.ToBoolean(m_value);
         }
 
-        char IConvertible.ToChar(IFormatProvider provider)
+        char IConvertible.ToChar(IFormatProvider? provider)
         {
             return Convert.ToChar(m_value);
         }
 
-        sbyte IConvertible.ToSByte(IFormatProvider provider)
+        sbyte IConvertible.ToSByte(IFormatProvider? provider)
         {
             return Convert.ToSByte(m_value);
         }
 
-        byte IConvertible.ToByte(IFormatProvider provider)
+        byte IConvertible.ToByte(IFormatProvider? provider)
         {
             return Convert.ToByte(m_value);
         }
 
-        short IConvertible.ToInt16(IFormatProvider provider)
+        short IConvertible.ToInt16(IFormatProvider? provider)
         {
             return Convert.ToInt16(m_value);
         }
 
-        ushort IConvertible.ToUInt16(IFormatProvider provider)
+        ushort IConvertible.ToUInt16(IFormatProvider? provider)
         {
             return m_value;
         }
 
-        int IConvertible.ToInt32(IFormatProvider provider)
+        int IConvertible.ToInt32(IFormatProvider? provider)
         {
             return Convert.ToInt32(m_value);
         }
 
-        uint IConvertible.ToUInt32(IFormatProvider provider)
+        uint IConvertible.ToUInt32(IFormatProvider? provider)
         {
             return Convert.ToUInt32(m_value);
         }
 
-        long IConvertible.ToInt64(IFormatProvider provider)
+        long IConvertible.ToInt64(IFormatProvider? provider)
         {
             return Convert.ToInt64(m_value);
         }
 
-        ulong IConvertible.ToUInt64(IFormatProvider provider)
+        ulong IConvertible.ToUInt64(IFormatProvider? provider)
         {
             return Convert.ToUInt64(m_value);
         }
 
-        float IConvertible.ToSingle(IFormatProvider provider)
+        float IConvertible.ToSingle(IFormatProvider? provider)
         {
             return Convert.ToSingle(m_value);
         }
 
-        double IConvertible.ToDouble(IFormatProvider provider)
+        double IConvertible.ToDouble(IFormatProvider? provider)
         {
             return Convert.ToDouble(m_value);
         }
 
-        decimal IConvertible.ToDecimal(IFormatProvider provider)
+        decimal IConvertible.ToDecimal(IFormatProvider? provider)
         {
             return Convert.ToDecimal(m_value);
         }
 
-        DateTime IConvertible.ToDateTime(IFormatProvider provider)
+        DateTime IConvertible.ToDateTime(IFormatProvider? provider)
         {
             throw new InvalidCastException(SR.Format(SR.InvalidCast_FromTo, "UInt16", "DateTime"));
         }
 
-        object IConvertible.ToType(Type type, IFormatProvider provider)
+        object IConvertible.ToType(Type type, IFormatProvider? provider)
         {
             return Convert.DefaultToType((IConvertible)this, type, provider);
         }
diff --git a/src/System.Private.CoreLib/shared/System/UInt32.cs b/src/System.Private.CoreLib/shared/System/UInt32.cs
index 19faee1730..400c45b9bc 100644
--- a/src/System.Private.CoreLib/shared/System/UInt32.cs
+++ b/src/System.Private.CoreLib/shared/System/UInt32.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -22,12 +23,12 @@ namespace System
 
 
         // Compares this object to another object, returning an integer that
-        // indicates the relationship. 
+        // indicates the relationship.
         // Returns a value less than zero if this  object
         // null is considered to be less than any instance.
         // If object is not of type UInt32, this method throws an ArgumentException.
-        // 
-        public int CompareTo(object value)
+        //
+        public int CompareTo(object? value)
         {
             if (value == null)
             {
@@ -54,7 +55,7 @@ namespace System
             return 0;
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (!(obj is uint))
             {
@@ -81,22 +82,22 @@ namespace System
             return Number.FormatUInt32(m_value, null, null);
         }
 
-        public string ToString(IFormatProvider provider)
+        public string ToString(IFormatProvider? provider)
         {
             return Number.FormatUInt32(m_value, null, provider);
         }
 
-        public string ToString(string format)
+        public string ToString(string? format)
         {
             return Number.FormatUInt32(m_value, format, null);
         }
 
-        public string ToString(string format, IFormatProvider provider)
+        public string ToString(string? format, IFormatProvider? provider)
         {
             return Number.FormatUInt32(m_value, format, provider);
         }
 
-        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider provider = null)
+        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider? provider = null)
         {
             return Number.TryFormatUInt32(m_value, format, provider, destination, out charsWritten);
         }
@@ -118,14 +119,14 @@ namespace System
 
 
         [CLSCompliant(false)]
-        public static uint Parse(string s, IFormatProvider provider)
+        public static uint Parse(string s, IFormatProvider? provider)
         {
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
             return Number.ParseUInt32(s, NumberStyles.Integer, NumberFormatInfo.GetInstance(provider));
         }
 
         [CLSCompliant(false)]
-        public static uint Parse(string s, NumberStyles style, IFormatProvider provider)
+        public static uint Parse(string s, NumberStyles style, IFormatProvider? provider)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
@@ -133,14 +134,14 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static uint Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static uint Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider? provider = null)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Number.ParseUInt32(s, style, NumberFormatInfo.GetInstance(provider));
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(string s, out uint result)
+        public static bool TryParse(string? s, out uint result)
         {
             if (s == null)
             {
@@ -158,7 +159,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(string s, NumberStyles style, IFormatProvider provider, out uint result)
+        public static bool TryParse(string? s, NumberStyles style, IFormatProvider? provider, out uint result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
 
@@ -172,7 +173,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider provider, out uint result)
+        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider? provider, out uint result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Number.TryParseUInt32(s, style, NumberFormatInfo.GetInstance(provider), out result) == Number.ParsingStatus.OK;
@@ -180,84 +181,84 @@ namespace System
 
         //
         // IConvertible implementation
-        // 
+        //
 
         public TypeCode GetTypeCode()
         {
             return TypeCode.UInt32;
         }
 
-        bool IConvertible.ToBoolean(IFormatProvider provider)
+        bool IConvertible.ToBoolean(IFormatProvider? provider)
         {
             return Convert.ToBoolean(m_value);
         }
 
-        char IConvertible.ToChar(IFormatProvider provider)
+        char IConvertible.ToChar(IFormatProvider? provider)
         {
             return Convert.ToChar(m_value);
         }
 
-        sbyte IConvertible.ToSByte(IFormatProvider provider)
+        sbyte IConvertible.ToSByte(IFormatProvider? provider)
         {
             return Convert.ToSByte(m_value);
         }
 
-        byte IConvertible.ToByte(IFormatProvider provider)
+        byte IConvertible.ToByte(IFormatProvider? provider)
         {
             return Convert.ToByte(m_value);
         }
 
-        short IConvertible.ToInt16(IFormatProvider provider)
+        short IConvertible.ToInt16(IFormatProvider? provider)
         {
             return Convert.ToInt16(m_value);
         }
 
-        ushort IConvertible.ToUInt16(IFormatProvider provider)
+        ushort IConvertible.ToUInt16(IFormatProvider? provider)
         {
             return Convert.ToUInt16(m_value);
         }
 
-        int IConvertible.ToInt32(IFormatProvider provider)
+        int IConvertible.ToInt32(IFormatProvider? provider)
         {
             return Convert.ToInt32(m_value);
         }
 
-        uint IConvertible.ToUInt32(IFormatProvider provider)
+        uint IConvertible.ToUInt32(IFormatProvider? provider)
         {
             return m_value;
         }
 
-        long IConvertible.ToInt64(IFormatProvider provider)
+        long IConvertible.ToInt64(IFormatProvider? provider)
         {
             return Convert.ToInt64(m_value);
         }
 
-        ulong IConvertible.ToUInt64(IFormatProvider provider)
+        ulong IConvertible.ToUInt64(IFormatProvider? provider)
         {
             return Convert.ToUInt64(m_value);
         }
 
-        float IConvertible.ToSingle(IFormatProvider provider)
+        float IConvertible.ToSingle(IFormatProvider? provider)
         {
             return Convert.ToSingle(m_value);
         }
 
-        double IConvertible.ToDouble(IFormatProvider provider)
+        double IConvertible.ToDouble(IFormatProvider? provider)
         {
             return Convert.ToDouble(m_value);
         }
 
-        decimal IConvertible.ToDecimal(IFormatProvider provider)
+        decimal IConvertible.ToDecimal(IFormatProvider? provider)
         {
             return Convert.ToDecimal(m_value);
         }
 
-        DateTime IConvertible.ToDateTime(IFormatProvider provider)
+        DateTime IConvertible.ToDateTime(IFormatProvider? provider)
         {
             throw new InvalidCastException(SR.Format(SR.InvalidCast_FromTo, "UInt32", "DateTime"));
         }
 
-        object IConvertible.ToType(Type type, IFormatProvider provider)
+        object IConvertible.ToType(Type type, IFormatProvider? provider)
         {
             return Convert.DefaultToType((IConvertible)this, type, provider);
         }
diff --git a/src/System.Private.CoreLib/shared/System/UInt64.cs b/src/System.Private.CoreLib/shared/System/UInt64.cs
index 39fa643127..049068eaa7 100644
--- a/src/System.Private.CoreLib/shared/System/UInt64.cs
+++ b/src/System.Private.CoreLib/shared/System/UInt64.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -21,12 +22,12 @@ namespace System
         public const ulong MinValue = 0x0;
 
         // Compares this object to another object, returning an integer that
-        // indicates the relationship. 
+        // indicates the relationship.
         // Returns a value less than zero if this  object
         // null is considered to be less than any instance.
         // If object is not of type UInt64, this method throws an ArgumentException.
-        // 
-        public int CompareTo(object value)
+        //
+        public int CompareTo(object? value)
         {
             if (value == null)
             {
@@ -53,7 +54,7 @@ namespace System
             return 0;
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             if (!(obj is ulong))
             {
@@ -79,22 +80,22 @@ namespace System
             return Number.FormatUInt64(m_value, null, null);
         }
 
-        public string ToString(IFormatProvider provider)
+        public string ToString(IFormatProvider? provider)
         {
             return Number.FormatUInt64(m_value, null, provider);
         }
 
-        public string ToString(string format)
+        public string ToString(string? format)
         {
             return Number.FormatUInt64(m_value, format, null);
         }
 
-        public string ToString(string format, IFormatProvider provider)
+        public string ToString(string? format, IFormatProvider? provider)
         {
             return Number.FormatUInt64(m_value, format, provider);
         }
 
-        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider provider = null)
+        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider? provider = null)
         {
             return Number.TryFormatUInt64(m_value, format, provider, destination, out charsWritten);
         }
@@ -115,14 +116,14 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static ulong Parse(string s, IFormatProvider provider)
+        public static ulong Parse(string s, IFormatProvider? provider)
         {
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
             return Number.ParseUInt64(s, NumberStyles.Integer, NumberFormatInfo.GetInstance(provider));
         }
 
         [CLSCompliant(false)]
-        public static ulong Parse(string s, NumberStyles style, IFormatProvider provider)
+        public static ulong Parse(string s, NumberStyles style, IFormatProvider? provider)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
@@ -130,14 +131,14 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static ulong Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static ulong Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider? provider = null)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Number.ParseUInt64(s, style, NumberFormatInfo.GetInstance(provider));
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(string s, out ulong result)
+        public static bool TryParse(string? s, out ulong result)
         {
             if (s == null)
             {
@@ -155,7 +156,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(string s, NumberStyles style, IFormatProvider provider, out ulong result)
+        public static bool TryParse(string? s, NumberStyles style, IFormatProvider? provider, out ulong result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
 
@@ -169,7 +170,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider provider, out ulong result)
+        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider? provider, out ulong result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
             return Number.TryParseUInt64(s, style, NumberFormatInfo.GetInstance(provider), out result) == Number.ParsingStatus.OK;
@@ -177,84 +178,84 @@ namespace System
 
         //
         // IConvertible implementation
-        // 
+        //
 
         public TypeCode GetTypeCode()
         {
             return TypeCode.UInt64;
         }
 
-        bool IConvertible.ToBoolean(IFormatProvider provider)
+        bool IConvertible.ToBoolean(IFormatProvider? provider)
         {
             return Convert.ToBoolean(m_value);
         }
 
-        char IConvertible.ToChar(IFormatProvider provider)
+        char IConvertible.ToChar(IFormatProvider? provider)
         {
             return Convert.ToChar(m_value);
         }
 
-        sbyte IConvertible.ToSByte(IFormatProvider provider)
+        sbyte IConvertible.ToSByte(IFormatProvider? provider)
         {
             return Convert.ToSByte(m_value);
         }
 
-        byte IConvertible.ToByte(IFormatProvider provider)
+        byte IConvertible.ToByte(IFormatProvider? provider)
         {
             return Convert.ToByte(m_value);
         }
 
-        short IConvertible.ToInt16(IFormatProvider provider)
+        short IConvertible.ToInt16(IFormatProvider? provider)
         {
             return Convert.ToInt16(m_value);
         }
 
-        ushort IConvertible.ToUInt16(IFormatProvider provider)
+        ushort IConvertible.ToUInt16(IFormatProvider? provider)
         {
             return Convert.ToUInt16(m_value);
         }
 
-        int IConvertible.ToInt32(IFormatProvider provider)
+        int IConvertible.ToInt32(IFormatProvider? provider)
         {
             return Convert.ToInt32(m_value);
         }
 
-        uint IConvertible.ToUInt32(IFormatProvider provider)
+        uint IConvertible.ToUInt32(IFormatProvider? provider)
         {
             return Convert.ToUInt32(m_value);
         }
 
-        long IConvertible.ToInt64(IFormatProvider provider)
+        long IConvertible.ToInt64(IFormatProvider? provider)
         {
             return Convert.ToInt64(m_value);
         }
 
-        ulong IConvertible.ToUInt64(IFormatProvider provider)
+        ulong IConvertible.ToUInt64(IFormatProvider? provider)
         {
             return m_value;
         }
 
-        float IConvertible.ToSingle(IFormatProvider provider)
+        float IConvertible.ToSingle(IFormatProvider? provider)
         {
             return Convert.ToSingle(m_value);
         }
 
-        double IConvertible.ToDouble(IFormatProvider provider)
+        double IConvertible.ToDouble(IFormatProvider? provider)
         {
             return Convert.ToDouble(m_value);
         }
 
-        decimal IConvertible.ToDecimal(IFormatProvider provider)
+        decimal IConvertible.ToDecimal(IFormatProvider? provider)
         {
             return Convert.ToDecimal(m_value);
         }
 
-        DateTime IConvertible.ToDateTime(IFormatProvider provider)
+        DateTime IConvertible.ToDateTime(IFormatProvider? provider)
         {
             throw new InvalidCastException(SR.Format(SR.InvalidCast_FromTo, "UInt64", "DateTime"));
         }
 
-        object IConvertible.ToType(Type type, IFormatProvider provider)
+        object IConvertible.ToType(Type type, IFormatProvider? provider)
         {
             return Convert.DefaultToType((IConvertible)this, type, provider);
         }