Make primitive types readonly

src/Common/src/CoreLib/System/DateTimeOffset.cs

@@ -33,7 +33,7 @@ namespace System
 #if !MONO
     [System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")] 
 #endif
-    public struct DateTimeOffset : IComparable, IFormattable, IComparable<DateTimeOffset>, IEquatable<DateTimeOffset>, ISerializable, IDeserializationCallback, ISpanFormattable
+    public readonly struct DateTimeOffset : IComparable, IFormattable, IComparable<DateTimeOffset>, IEquatable<DateTimeOffset>, ISerializable, IDeserializationCallback, ISpanFormattable
     {
         // Constants
         internal const Int64 MaxOffset = TimeSpan.TicksPerHour * 14;
@@ -51,8 +51,8 @@ public struct DateTimeOffset : IComparable, IFormattable, IComparable<DateTimeOf
         public static readonly DateTimeOffset UnixEpoch = new DateTimeOffset(DateTime.UnixEpochTicks, TimeSpan.Zero);
 
         // Instance Fields
-        private DateTime _dateTime;
-        private Int16 _offsetMinutes;
+        private readonly DateTime _dateTime;
+        private readonly Int16 _offsetMinutes;
 
         // Constructors
 
@@ -555,8 +555,8 @@ void IDeserializationCallback.OnDeserialization(Object sender)
         {
             try
             {
-                _offsetMinutes = ValidateOffset(Offset);
-                _dateTime = ValidateDate(ClockDateTime, Offset);
+                ValidateOffset(Offset);
+                ValidateDate(ClockDateTime, Offset);
             }
             catch (ArgumentException e)
             {

src/Common/src/CoreLib/System/Double.cs

@@ -26,9 +26,9 @@ namespace System
 #if !MONO
     [TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
 #endif
-    public struct Double : IComparable, IConvertible, IFormattable, IComparable<Double>, IEquatable<Double>, ISpanFormattable
+    public readonly struct Double : IComparable, IConvertible, IFormattable, IComparable<Double>, IEquatable<Double>, ISpanFormattable
     {
-        private double m_value; // Do not rename (binary serialization)
+        private readonly double m_value; // Do not rename (binary serialization)
 
         //
         // Public Constants
@@ -228,7 +228,7 @@ public bool Equals(Double obj)
         [MethodImpl(MethodImplOptions.AggressiveInlining)] // 64-bit constants make the IL unusually large that makes the inliner to reject the method
         public override int GetHashCode()
         {
-            var bits = Unsafe.As<double, long>(ref m_value);
+            var bits = BitConverter.DoubleToInt64Bits(m_value);
 
             // Optimized check for IsNan() || IsZero()
             if (((bits - 1) & 0x7FFFFFFFFFFFFFFF) >= 0x7FF0000000000000)

src/Common/src/CoreLib/System/Globalization/TimeSpanParse.cs

@@ -766,7 +766,7 @@ private static bool ProcessTerminal_DHMSF(ref TimeSpanRawInfo raw, TimeSpanStand
                     }
                 }
 
-                result.parsedTimeSpan._ticks = ticks;
+                result.parsedTimeSpan = new TimeSpan(ticks);
                 return true;
             }
 
@@ -894,7 +894,7 @@ private static bool ProcessTerminal_HMS_F_D(ref TimeSpanRawInfo raw, TimeSpanSta
                     }
                 }
 
-                result.parsedTimeSpan._ticks = ticks;
+                result.parsedTimeSpan = new TimeSpan(ticks);
                 return true;
             }
 
@@ -1020,7 +1020,7 @@ private static bool ProcessTerminal_HM_S_D(ref TimeSpanRawInfo raw, TimeSpanStan
                     }
                 }
 
-                result.parsedTimeSpan._ticks = ticks;
+                result.parsedTimeSpan = new TimeSpan(ticks);
                 return true;
             }
 
@@ -1092,7 +1092,7 @@ private static bool ProcessTerminal_HM(ref TimeSpanRawInfo raw, TimeSpanStandard
                     }
                 }
 
-                result.parsedTimeSpan._ticks = ticks;
+                result.parsedTimeSpan = new TimeSpan(ticks);
                 return true;
             }
 
@@ -1162,7 +1162,7 @@ private static bool ProcessTerminal_D(ref TimeSpanRawInfo raw, TimeSpanStandardS
                     }
                 }
 
-                result.parsedTimeSpan._ticks = ticks;
+                result.parsedTimeSpan = new TimeSpan(ticks);
                 return true;
             }
 
@@ -1361,7 +1361,7 @@ private static bool TryParseByFormat(ReadOnlySpan<char> input, ReadOnlySpan<char
                     ticks = -ticks;
                 }
 
-                result.parsedTimeSpan._ticks = ticks;
+                result.parsedTimeSpan = new TimeSpan(ticks);
                 return true;
             }
             else
@@ -1456,7 +1456,7 @@ internal char NextNonDigit()
 
             internal bool TryParse(ReadOnlySpan<char> input, ref TimeSpanResult result)
             {
-                result.parsedTimeSpan._ticks = 0;
+                result.parsedTimeSpan = default;
 
                 _str = input;
                 _len = input.Length;
@@ -1525,7 +1525,7 @@ internal bool TryParse(ReadOnlySpan<char> input, ref TimeSpanResult result)
                     return result.SetFailure(ParseFailureKind.Format, nameof(SR.Format_BadTimeSpan));
                 }
 
-                result.parsedTimeSpan._ticks = time;
+                result.parsedTimeSpan = new TimeSpan(time);
                 return true;
             }
 

src/Common/src/CoreLib/System/Single.cs

@@ -25,9 +25,9 @@ namespace System
 #if !MONO
     [TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
 #endif
-    public struct Single : IComparable, IConvertible, IFormattable, IComparable<Single>, IEquatable<Single>, ISpanFormattable
+    public readonly struct Single : IComparable, IConvertible, IFormattable, IComparable<Single>, IEquatable<Single>, ISpanFormattable
     {
-        private float m_value; // Do not rename (binary serialization)
+        private readonly float m_value; // Do not rename (binary serialization)
 
         //
         // Public constants
@@ -219,7 +219,7 @@ public bool Equals(Single obj)
 
         public override int GetHashCode()
         {
-            var bits = Unsafe.As<float, int>(ref m_value);
+            var bits = BitConverter.SingleToInt32Bits(m_value);
 
             // Optimized check for IsNan() || IsZero()
             if (((bits - 1) & 0x7FFFFFFF) >= 0x7F800000)

src/Common/src/CoreLib/System/TimeSpan.cs

@@ -28,7 +28,7 @@ namespace System
     // an appropriate custom ILMarshaler to keep WInRT interop scenarios enabled.
     //
     [Serializable]
-    public struct TimeSpan : IComparable, IComparable<TimeSpan>, IEquatable<TimeSpan>, IFormattable, ISpanFormattable
+    public readonly struct TimeSpan : IComparable, IComparable<TimeSpan>, IEquatable<TimeSpan>, IFormattable, ISpanFormattable
     {
         public const long TicksPerMillisecond = 10000;
         private const double MillisecondsPerTick = 1.0 / TicksPerMillisecond;
@@ -65,7 +65,7 @@ public struct TimeSpan : IComparable, IComparable<TimeSpan>, IEquatable<TimeSpan
 
         // internal so that DateTime doesn't have to call an extra get
         // method for some arithmetic operations.
-        internal long _ticks; // Do not rename (binary serialization)
+        internal readonly long _ticks; // Do not rename (binary serialization)
 
         public TimeSpan(long ticks)
         {

src/System.Data.Common/src/System/Data/DataSet.cs

@@ -29,7 +29,7 @@ namespace System.Data
     [XmlRoot(nameof(DataSet))]
 #if !MONO
     [System.Runtime.CompilerServices.TypeForwardedFrom("System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
-else
+#else
     [System.ComponentModel.ToolboxItemAttribute("Microsoft.VSDesigner.Data.VS.DataSetToolboxItem, Microsoft.VSDesigner, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")]
 #endif
     public class DataSet : MarshalByValueComponent, IListSource, IXmlSerializable, ISupportInitializeNotification, ISerializable