[API Compat] Fix attribute comparison in type members

src/Microsoft.DotNet.ApiCompat/src/Rules/Compat/AttributeDifference.cs

@@ -83,7 +83,7 @@ public override DifferenceType Diff(IDifferences differences, ITypeDefinitionMem
             if (implMethod == null || contractMethod == null)
                 return DifferenceType.Unknown;
 
-            bool changed = CheckAttributeDifferences(differences, implMethod, implMethod.Attributes, implMethod.Attributes);
+            bool changed = CheckAttributeDifferences(differences, implMethod, implMethod.Attributes, contractMethod.Attributes);
 
             IParameterDefinition[] method1Params = implMethod.Parameters.ToArray();
             IParameterDefinition[] method2Params = contractMethod.Parameters.ToArray();

src/Microsoft.DotNet.ApiCompat/tests/AttributeDifferenceTests.cs

@@ -22,9 +22,10 @@ public void AttributeDifferenceIsFound()
             Assert.Contains("CannotRemoveAttribute : Attribute 'AttributeDifference.FooAttribute' exists on 'AttributeDifference.AttributeDifferenceClass1' in the implementation but not the contract.", runOutput);
             Assert.Contains("CannotRemoveAttribute : Attribute 'System.ComponentModel.DefaultValueAttribute' exists on generic param 'T' on member 'AttributeDifference.AttributeDifferenceClass1.GenericMethodWithAttribute<T>()' in the implementation but not the contract.", runOutput);
             Assert.Contains("CannotRemoveAttribute : Attribute 'System.ComponentModel.DefaultValueAttribute' exists on generic param 'T' on member 'AttributeDifference.AttributeDifferenceClass1.GenericMethodWithAttribute<T>()' in the implementation but not the contract.", runOutput);
+            Assert.Contains("CannotRemoveAttribute : Attribute 'AttributeDifference.FooAttribute' exists on 'AttributeDifference.AttributeDifferenceClass1.MethodWithAttribute()' in the implementation but not the contract.", runOutput);
             Assert.Contains("CannotRemoveAttribute : Attribute 'AttributeDifference.FooAttribute' exists on parameter 'myParameter' on member 'AttributeDifference.AttributeDifferenceClass1.MethodWithAttribute(System.String, System.Object)' in the implementation but not the contract.", runOutput);
             Assert.Contains("CannotRemoveAttribute : Attribute 'System.ComponentModel.DefaultValueAttribute' exists on generic param 'TOne' on member 'AttributeDifference.AttributeDifferenceGenericCLass<TOne, TTwo>' in the implementation but not the contract.", runOutput);
-            Assert.Contains("Total Issues: 5", runOutput);
+            Assert.Contains("Total Issues: 6", runOutput);
         }
 
         [Fact]

src/Microsoft.DotNet.ApiCompat/tests/TestProjects/AttributeDifference/Contract/AttributeDifference.cs

@@ -10,6 +10,7 @@ public class AttributeDifferenceClass1
     {
         public string MethodWithAttribute(string myParameter, [DefaultValue("myObject")] object myObject) => throw null;
         public T GenericMethodWithAttribute<T>() => throw null;
+        public void MethodWithAttribute() { }
     }
     public class AttributeDifferenceGenericCLass<TOne, [DefaultValue("TTwo")] TTwo>
     {

src/Microsoft.DotNet.ApiCompat/tests/TestProjects/AttributeDifference/Implementation/AttributeDifferenceClass1.cs

@@ -13,6 +13,8 @@ public class AttributeDifferenceClass1
     {
         public string MethodWithAttribute([Foo] string myParameter, [DefaultValue("myObject")] object myObject) => myParameter;
         public T GenericMethodWithAttribute<[DefaultValue("T")] T>() => default(T);
+        [Foo]
+        public void MethodWithAttribute() { }
     }
 
     public class AttributeDifferenceGenericCLass<[DefaultValue("TOne")] TOne, [DefaultValue("TTwo")] TTwo>