Add new extensions methods for DateTime

src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -252,6 +252,7 @@
     <Compile Include="$(CommonPath)System\Experimentals.cs">
       <Link>Common\System\Experimentals.cs</Link>
     </Compile>
+    <Compile Include="src\System\Extensions\DateTimeExtensions.cs" />
     <Compile Include="src\System\RuntimeType.BoxCache.cs" />
     <Compile Include="src\System\RuntimeType.CreateUninitializedCache.CoreCLR.cs" />
     <Compile Include="src\System\RuntimeType.GenericCache.cs" />
@@ -325,4 +326,7 @@
   <ItemGroup Condition="'$(FeaturePerfTracing)' == 'true'">
     <AdditionalFiles Include="$(CoreClrProjectRoot)vm/ClrEtwAll.man" />
   </ItemGroup>
+  <ItemGroup>
+    <Folder Include="system.private.corelib\src\system\extensions\" />
+  </ItemGroup>
 </Project>

src/coreclr/System.Private.CoreLib/src/System/Extensions/DateTimeExtensions.cs

@@ -0,0 +1,77 @@
+namespace System.Private.CoreLib.src.System.Extensions;
+
+/// <summary>
+/// Contains extension methods for <see cref="DateTime"/>
+/// </summary>
+public static class DateTimeExtensions
+{
+    extension(DateTime dateTime)
+    {
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="DateOnly"/>
+        /// </summary>
+        /// <returns><see cref="DateOnly"/></returns>
+        public DateOnly ToDateOnly() =>
+            DateOnly.FromDateTime(dateTime);
+
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="TimeOnly"/>
+        /// </summary>
+        /// <returns><see cref="TimeOnly"/></returns>
+        public TimeOnly ToTimeOnly() =>
+            TimeOnly.FromDateTime(dateTime);
+    }
+
+    extension(DateTime? dateTime)
+    {
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="DateOnly"/>
+        /// </summary>
+        /// <returns><see cref="DateOnly"/></returns>
+        public DateOnly ToDateOnly() =>
+            DateOnly.FromDateTime(dateTime.Value);
+
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="TimeOnly"/>
+        /// </summary>
+        /// <returns><see cref="TimeOnly"/></returns>
+        public TimeOnly ToTimeOnly() =>
+            TimeOnly.FromDateTime(dateTime.Value);
+
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="DateOnly"/>
+        /// </summary>
+        /// <returns><see cref="DateOnly"/> is <paramref name="dateTime"/> is null returns null</returns>
+        public DateOnly? ToDateOnlyOrNull() =>
+            dateTime is not null
+                ? dateTime.Value.ToDateOnly()
+                : null;
+
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="TimeOnly"/>
+        /// </summary>
+        /// <returns><see cref="TimeOnly"/> is <paramref name="dateTime"/> is null returns null</returns>
+        public TimeOnly? ToTimeOnlyOrNull() =>
+            dateTime is not null
+                ? dateTime.Value.ToTimeOnly()
+                : null;
+
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="DateOnly"/>
+        /// </summary>
+        /// <returns><see cref="DateOnly"/> is <paramref name="dateTime"/> is null returns default value</returns>
+        public DateOnly ToDateOnlyOrDefault() =>
+            dateTime is not null
+                ? dateTime.Value.ToDateOnly()
+                : default;
+
+        /// <summary>
+        /// Converts <see cref="DateTime"/> to <see cref="TimeOnly"/>
+        /// </summary>
+        /// <returns><see cref="TimeOnly"/> is <paramref name="dateTime"/> is null returns default value</returns>
+        public TimeOnly ToTimeOnlyOrDefault() =>
+            dateTime is not null
+                ? dateTime.Value.ToTimeOnly()
+                : default;
+    }
+}

src/libraries/System.Private.CoreLib/src/System/DateTime.cs

@@ -9,7 +9,6 @@
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
-using System.Runtime.Versioning;
 
 namespace System
 {