Rename mscorlib to System.Private.Corelib (#17926)

* diff from just renaming folder mscorlib to System.Private.CoreLib

* Updating build.proj to reflect name change

Fixes: #17905

1 files changed, 119 insertions, 0 deletions

diff --git a/src/System.Private.CoreLib/shared/System/DBNull.cs b/src/System.Private.CoreLib/shared/System/DBNull.cs
new file mode 100644
index 0000000000..3cee2b15c8
--- /dev/null
+++ b/src/System.Private.CoreLib/shared/System/DBNull.cs
@@ -0,0 +1,119 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.Serialization;
+
+namespace System
+{
+    [Serializable]
+    public sealed class DBNull : ISerializable, IConvertible
+    {
+        private DBNull()
+        {
+        }
+
+        private DBNull(SerializationInfo info, StreamingContext context)
+        {
+            throw new NotSupportedException(SR.NotSupported_DBNullSerial);
+        }
+
+        public static readonly DBNull Value = new DBNull();
+
+        public void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+            UnitySerializationHolder.GetUnitySerializationInfo(info, UnitySerializationHolder.NullUnity);
+        }
+
+        public override string ToString()
+        {
+            return string.Empty;
+        }
+
+        public string ToString(IFormatProvider provider)
+        {
+            return string.Empty;
+        }
+
+        public TypeCode GetTypeCode()
+        {
+            return TypeCode.DBNull;
+        }
+
+        bool IConvertible.ToBoolean(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        char IConvertible.ToChar(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        sbyte IConvertible.ToSByte(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        byte IConvertible.ToByte(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        short IConvertible.ToInt16(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        ushort IConvertible.ToUInt16(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        int IConvertible.ToInt32(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        uint IConvertible.ToUInt32(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        long IConvertible.ToInt64(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        ulong IConvertible.ToUInt64(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        float IConvertible.ToSingle(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        double IConvertible.ToDouble(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        decimal IConvertible.ToDecimal(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        DateTime IConvertible.ToDateTime(IFormatProvider provider)
+        {
+            throw new InvalidCastException(SR.InvalidCast_FromDBNull);
+        }
+
+        object IConvertible.ToType(Type type, IFormatProvider provider)
+        {
+            return Convert.DefaultToType((IConvertible)this, type, provider);
+        }
+    }
+}
+