Add .NET 4.6.1 target that will be the minimal version for binary serialization.

Author: KeRNeLith

src/QuikGraph.Serialization/QuikGraph.Serialization.csproj

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net35;net40;netstandard1.3;netstandard2.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks>net35;net40;net461;netstandard1.3;netstandard2.0;netstandard2.1</TargetFrameworks>
 
     <GeneratePackageOnBuild>$(Generate_QuikGraph_Serialization)</GeneratePackageOnBuild>
 
@@ -42,12 +42,16 @@ Updates:
   <!-- Targets defines -->
   <PropertyGroup Condition="'$(TargetFramework)'=='net35'">
     <AssemblyTitle>QuikGraph.Serialization .NET 3.5</AssemblyTitle>
-    <DefineConstants>$(DefineConstants);NET35;SUPPORTS_SERIALIZATION;SUPPORTS_GRAPHS_SERIALIZATION;$(AdditionalConstants)</DefineConstants>
+    <DefineConstants>$(DefineConstants);NET35;SUPPORTS_SERIALIZATION;SUPPORTS_GRAPHS_SERIALIZATION;DEPRECATE_BINARY_SERIALIZATION;$(AdditionalConstants)</DefineConstants>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <PropertyGroup Condition="'$(TargetFramework)'=='net40'">
     <AssemblyTitle>QuikGraph.Serialization .NET 4.0</AssemblyTitle>
-    <DefineConstants>$(DefineConstants);NET40;SUPPORTS_SERIALIZATION;SUPPORTS_GRAPHS_SERIALIZATION;SUPPORTS_XML_DTD_PROCESSING;$(AdditionalConstants)</DefineConstants>
+    <DefineConstants>$(DefineConstants);NET40;SUPPORTS_SERIALIZATION;SUPPORTS_GRAPHS_SERIALIZATION;DEPRECATE_BINARY_SERIALIZATION;SUPPORTS_XML_DTD_PROCESSING;$(AdditionalConstants)</DefineConstants>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(TargetFramework)'=='net461'">
+    <AssemblyTitle>QuikGraph.Serialization .NET 4.6.1</AssemblyTitle>
+    <DefineConstants>$(DefineConstants);NET461;SUPPORTS_SERIALIZATION;SUPPORTS_GRAPHS_SERIALIZATION;SUPPORTS_XML_DTD_PROCESSING;$(AdditionalConstants)</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition="'$(TargetFramework)'=='netstandard1.3'">
     <AssemblyTitle>QuikGraph.Serialization .NET Standard 1.3</AssemblyTitle>

src/QuikGraph.Serialization/SerializationExtensions.cs

@@ -26,6 +26,11 @@ public static class SerializationExtensions
         /// <exception cref="T:System.ArgumentNullException"><paramref name="graph"/> is <see langword="null"/>.</exception>
         /// <exception cref="T:System.ArgumentNullException"><paramref name="stream"/> is <see langword="null"/>.</exception>
         /// <exception cref="T:System.ArgumentException"><paramref name="stream"/> is not writable.</exception>
+#if DEPRECATE_BINARY_SERIALIZATION
+        [Obsolete(
+            "Binary serialization on old .NET targets is deprecated.\n" +
+            "Consider using another kind of serialization or updating to at least .NET Framework 4.6.1+, .NET Standard 2.0+ or .NET 5.0+.")]
+#endif
         public static void SerializeToBinary<TVertex, TEdge>(
             [NotNull] this IGraph<TVertex, TEdge> graph,
             [NotNull] Stream stream)
@@ -61,6 +66,11 @@ public static void SerializeToBinary<TVertex, TEdge>(
         /// <exception cref="T:System.ArgumentNullException"><paramref name="stream"/> is <see langword="null"/>.</exception>
         /// <exception cref="T:System.ArgumentException"><paramref name="stream"/> is not readable.</exception>
         [Pure]
+#if DEPRECATE_BINARY_SERIALIZATION
+        [Obsolete(
+            "Binary deserialization on old .NET targets is deprecated.\n" +
+            "Consider using another kind of serialization or updating to at least .NET Framework 4.6.1+, .NET Standard 2.0+ or .NET 5.0+.")]
+#endif
         public static TGraph DeserializeFromBinary<TVertex, TEdge, TGraph>(
             [NotNull] this Stream stream,
             [CanBeNull] SerializationBinder binder = null)

tests/QuikGraph.Serialization.Tests/BinarySerializationTests.cs

@@ -4,6 +4,8 @@
 using NUnit.Framework;
 using static QuikGraph.Serialization.Tests.SerializationTestCaseSources;
 
+#pragma warning disable 618 // Obsolete API usage
+
 namespace QuikGraph.Serialization.Tests
 {
     /// <summary>