Move serialization specific BitArray helpers to where they are used

src/Workspaces/Core/Portable/Shared/Utilities/BitArrayUtilities.cs

-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-
-using System;
-using System.Collections;
-using Roslyn.Utilities;
-
-namespace Microsoft.CodeAnalysis.Shared.Utilities
-{
-    internal static class BitArrayUtilities
-    {
-        private const string SerializationFormat = "0";
-
-        public static void WriteTo(this BitArray bitArray, ObjectWriter writer)
-        {
-            // Our serialization format doesn't round-trip bit arrays of non-byte lengths
-            Contract.ThrowIfTrue(bitArray.Length % 8 != 0);
-
-            writer.WriteString(SerializationFormat);
-            writer.WriteInt32(bitArray.Length / 8);
-
-            // This will hold the byte that we will write out after we process every 8 bits. This is
-            // LSB, so we push bits into it from the MSB.
-            byte b = 0;
-
-            for (var i = 0; i < bitArray.Length; i++)
-            {
-                if (bitArray[i])
-                {
-                    b = (byte)(0x80 | b >> 1);
-                }
-                else
-                {
-                    b >>= 1;
-                }
-
-                if ((i + 1) % 8 == 0)
-                {
-                    // End of a byte, write out the byte
-                    writer.WriteByte(b);
-                }
-            }
-        }
-
-        public static BitArray ReadFrom(this ObjectReader reader)
-        {
-            var version = reader.ReadString();
-            if (!string.Equals(version, SerializationFormat, StringComparison.Ordinal))
-            {
-                return null;
-            }
-
-            // TODO: find a way to use pool
-            var length = reader.ReadInt32();
-            var bytes = new byte[length];
-
-            for (var i = 0; i < bytes.Length; i++)
-            {
-                bytes[i] = reader.ReadByte();
-            }
-
-            return new BitArray(bytes);
-        }
-    }
-}

src/Workspaces/Core/Portable/Shared/Utilities/BloomFilter_Serialization.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
+using System.Collections;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Shared.Utilities
@@ -14,7 +15,37 @@ public void WriteTo(ObjectWriter writer)
             writer.WriteString(SerializationFormat);
             writer.WriteBoolean(_isCaseSensitive);
             writer.WriteInt32(_hashFunctionCount);
-            _bitArray.WriteTo(writer);
+            WriteBitArray(writer, _bitArray);
+        }
+
+        private static void WriteBitArray(ObjectWriter writer, BitArray bitArray)
+        {
+            // Our serialization format doesn't round-trip bit arrays of non-byte lengths
+            Contract.ThrowIfTrue(bitArray.Length % 8 != 0);
+
+            writer.WriteInt32(bitArray.Length / 8);
+
+            // This will hold the byte that we will write out after we process every 8 bits. This is
+            // LSB, so we push bits into it from the MSB.
+            byte b = 0;
+
+            for (var i = 0; i < bitArray.Length; i++)
+            {
+                if (bitArray[i])
+                {
+                    b = (byte)(0x80 | b >> 1);
+                }
+                else
+                {
+                    b >>= 1;
+                }
+
+                if ((i + 1) % 8 == 0)
+                {
+                    // End of a byte, write out the byte
+                    writer.WriteByte(b);
+                }
+            }
         }
 
         public static BloomFilter ReadFrom(ObjectReader reader)
@@ -27,13 +58,22 @@ public static BloomFilter ReadFrom(ObjectReader reader)
 
             var isCaseSensitive = reader.ReadBoolean();
             int hashFunctionCount = reader.ReadInt32();
-            var bitArray = BitArrayUtilities.ReadFrom(reader);
-            if (bitArray == null)
+            var bitArray = ReadBitArray(reader);
+            return new BloomFilter(bitArray, hashFunctionCount, isCaseSensitive);
+        }
+
+        private static BitArray ReadBitArray(ObjectReader reader)
+        {
+            // TODO: find a way to use pool
+            var length = reader.ReadInt32();
+            var bytes = new byte[length];
+
+            for (var i = 0; i < bytes.Length; i++)
             {
-                return null;
+                bytes[i] = reader.ReadByte();
             }
 
-            return new BloomFilter(bitArray, hashFunctionCount, isCaseSensitive);
+            return new BitArray(bytes);
         }
     }
 }

src/Workspaces/Core/Portable/Workspaces.csproj

@@ -693,7 +693,6 @@
     <Compile Include="Shared\Extensions\TextSpanExtensions.cs" />
     <Compile Include="Shared\NormalizedTextSpanCollection.cs" />
     <Compile Include="Shared\Utilities\AliasSymbolCache.cs" />
-    <Compile Include="Shared\Utilities\BitArrayUtilities.cs" />
     <Compile Include="Shared\Utilities\BloomFilter.cs" />
     <Compile Include="Shared\Utilities\BloomFilter_Serialization.cs" />
     <Compile Include="Shared\Utilities\CommonFormattingHelpers.cs" />