From 72ea22bce03ca91d2304283c131dbc3e2350cf88 Mon Sep 17 00:00:00 2001
From: Jesse Gielen <jessegielen@hotmail.com>
Date: Sun, 24 Jun 2018 16:00:04 +0200
Subject: [PATCH 1/2] Remove NotNull guard on value type

---
 .../Processing/Dithering/ErrorDiffusion/ErrorDiffuserBase.cs     | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/ImageSharp/Processing/Dithering/ErrorDiffusion/ErrorDiffuserBase.cs b/src/ImageSharp/Processing/Dithering/ErrorDiffusion/ErrorDiffuserBase.cs
index 3bc1df0bb2..f88123e5d5 100644
--- a/src/ImageSharp/Processing/Dithering/ErrorDiffusion/ErrorDiffuserBase.cs
+++ b/src/ImageSharp/Processing/Dithering/ErrorDiffusion/ErrorDiffuserBase.cs
@@ -47,7 +47,6 @@ namespace SixLabors.ImageSharp.Processing.Dithering.ErrorDiffusion
         /// <param name="divisor">The divisor.</param>
         internal ErrorDiffuserBase(DenseMatrix<float> matrix, byte divisor)
         {
-            Guard.NotNull(matrix, nameof(matrix));
             Guard.MustBeGreaterThan(divisor, 0, nameof(divisor));
 
             this.matrix = matrix;

From d171acba8051063a68467e912f1a81fae1126ed8 Mon Sep 17 00:00:00 2001
From: Anton Firsov <antonfir@gmail.com>
Date: Tue, 26 Jun 2018 09:34:15 +0200
Subject: [PATCH 2/2] make Guard.NotNull() and DebugGuard.NotNull() generic
 (#634)

---
 src/ImageSharp/Common/Helpers/DebugGuard.cs  | 9 +++++----
 src/ImageSharp/Common/Helpers/Guard.cs       | 3 ++-
 tests/ImageSharp.Tests/Helpers/GuardTests.cs | 8 ++++++--
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/ImageSharp/Common/Helpers/DebugGuard.cs b/src/ImageSharp/Common/Helpers/DebugGuard.cs
index 6dcd0fd270..5a1d3a2e35 100644
--- a/src/ImageSharp/Common/Helpers/DebugGuard.cs
+++ b/src/ImageSharp/Common/Helpers/DebugGuard.cs
@@ -17,13 +17,14 @@ namespace SixLabors.ImageSharp
         /// Verifies, that the method parameter with specified object value is not null
         /// and throws an exception if it is found to be so.
         /// </summary>
-        /// <param name="target">The target object, which cannot be null.</param>
+        /// <param name="value">The target object, which cannot be null.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
-        /// <exception cref="ArgumentNullException"><paramref name="target"/> is null</exception>
+        /// <exception cref="ArgumentNullException"><paramref name="value"/> is null</exception>
         [Conditional("DEBUG")]
-        public static void NotNull(object target, string parameterName)
+        public static void NotNull<T>(T value, string parameterName)
+            where T : class
         {
-            if (target == null)
+            if (value == null)
             {
                 throw new ArgumentNullException(parameterName);
             }
diff --git a/src/ImageSharp/Common/Helpers/Guard.cs b/src/ImageSharp/Common/Helpers/Guard.cs
index 011d7fdaac..d090790622 100644
--- a/src/ImageSharp/Common/Helpers/Guard.cs
+++ b/src/ImageSharp/Common/Helpers/Guard.cs
@@ -19,7 +19,8 @@ namespace SixLabors.ImageSharp
         /// <param name="value">The target object, which cannot be null.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <exception cref="ArgumentNullException"><paramref name="value"/> is null</exception>
-        public static void NotNull(object value, string parameterName)
+        public static void NotNull<T>(T value, string parameterName)
+            where T : class
         {
             if (value == null)
             {
diff --git a/tests/ImageSharp.Tests/Helpers/GuardTests.cs b/tests/ImageSharp.Tests/Helpers/GuardTests.cs
index 42913e02d4..0d1bb5ce9f 100644
--- a/tests/ImageSharp.Tests/Helpers/GuardTests.cs
+++ b/tests/ImageSharp.Tests/Helpers/GuardTests.cs
@@ -12,13 +12,17 @@ namespace SixLabors.ImageSharp.Tests.Helpers
     /// </summary>
     public class GuardTests
     {
+        class Test
+        {
+        }
+
         /// <summary>
         /// Tests that the <see cref="M:Guard.NotNull"/> method throws when the argument is null.
         /// </summary>
         [Fact]
         public void NotNullThrowsWhenArgIsNull()
         {
-            Assert.Throws<ArgumentNullException>(() => Guard.NotNull(null, "foo"));
+            Assert.Throws<ArgumentNullException>(() => Guard.NotNull((Test)null, "foo"));
         }
 
         /// <summary>
@@ -27,7 +31,7 @@ namespace SixLabors.ImageSharp.Tests.Helpers
         [Fact]
         public void NotNullThrowsWhenArgNameEmpty()
         {
-            Assert.Throws<ArgumentNullException>(() => Guard.NotNull(null, string.Empty));
+            Assert.Throws<ArgumentNullException>(() => Guard.NotNull((Test)null, string.Empty));
         }
 
         /// <summary>