fourth bug fix: don't cast bytes to DateTimes

Author: adamsitnik

src/libraries/System.Formats.Nrbf/src/System/Formats/Nrbf/ArraySinglePrimitiveRecord.cs

@@ -175,6 +175,17 @@ internal static IReadOnlyList<T> DecodePrimitiveTypes(BinaryReader reader, int c
                 }
             }
         }
+        else if (typeof(T) == typeof(DateTime))
+        {
+            DateTime[] dateTimes = (DateTime[])(object)result;
+            Span<ulong> span = MemoryMarshal.Cast<T, ulong>(result);
+            for (int i = 0; i < dateTimes.Length; i++)
+            {
+                // The value needs to get validated.
+                dateTimes[i] = BinaryReaderExtensions.CreateDateTimeFromData(span[i]);
+            }
+        }
+
         return result;
     }
 

src/libraries/System.Formats.Nrbf/tests/ArraySinglePrimitiveRecordTests.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using System.IO;
+using System.Runtime.Serialization;
 using System.Text;
 using Xunit;
 
@@ -52,6 +53,24 @@ public void DontCastBytesToBooleans()
         Assert.True(c);
     }
 
+    [Fact]
+    public void DontCastBytesToDateTimes()
+    {
+        using MemoryStream stream = new();
+        BinaryWriter writer = new(stream, Encoding.UTF8);
+
+        WriteSerializedStreamHeader(writer);
+        writer.Write((byte)SerializationRecordType.ArraySinglePrimitive);
+        writer.Write(1); // object ID
+        writer.Write(1); // length
+        writer.Write((byte)PrimitiveType.DateTime); // element type
+        writer.Write(ulong.MaxValue); // un-representable DateTime
+        writer.Write((byte)SerializationRecordType.MessageEnd);
+        stream.Position = 0;
+
+        Assert.Throws<SerializationException>(() => NrbfDecoder.Decode(stream));
+    }
+
     [Theory]
     [MemberData(nameof(GetCanReadArrayOfAnySizeArgs))]
     public void CanReadArrayOfAnySize_Bool(int size, bool canSeek) => Test<bool>(size, canSeek);