From 9f77f08a63e6bf28efa41a6d12fd0375b0ee3a95 Mon Sep 17 00:00:00 2001
From: Blaise Taylor <btaylor@bPolicySolutions.com>
Date: Mon, 13 May 2024 05:52:23 -0400
Subject: [PATCH] Always create instance methods using the declaring type. 
 Fixes Issue #179. (#180)

---
 .../XpressionMapperVisitor.cs                 | 16 +++-
 ...dUseDeclaringTypeForInstanceMethodCalls.cs | 83 +++++++++++++++++++
 2 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100644 tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/ShouldUseDeclaringTypeForInstanceMethodCalls.cs

diff --git a/src/AutoMapper.Extensions.ExpressionMapping/XpressionMapperVisitor.cs b/src/AutoMapper.Extensions.ExpressionMapping/XpressionMapperVisitor.cs
index 88ad595..0a92b62 100644
--- a/src/AutoMapper.Extensions.ExpressionMapping/XpressionMapperVisitor.cs
+++ b/src/AutoMapper.Extensions.ExpressionMapping/XpressionMapperVisitor.cs
@@ -569,9 +569,19 @@ protected override Expression VisitMethodCall(MethodCallExpression node)
                     : GetInstanceExpression(this.Visit(node.Object));
 
             MethodCallExpression GetInstanceExpression(Expression instance)
-                => node.Method.IsGenericMethod
-                    ? Expression.Call(instance, node.Method.Name, typeArgsForNewMethod.ToArray(), listOfArgumentsForNewMethod.ToArray())
-                    : Expression.Call(instance, instance.Type.GetMethod(node.Method.Name, listOfArgumentsForNewMethod.Select(a => a.Type).ToArray()), listOfArgumentsForNewMethod.ToArray());
+            {
+                return node.Method.IsGenericMethod
+                            ? Expression.Call(instance, node.Method.Name, typeArgsForNewMethod.ToArray(), listOfArgumentsForNewMethod.ToArray())
+                            : Expression.Call(instance, GetMethodInfoForNonGeneric(), listOfArgumentsForNewMethod.ToArray());
+
+                MethodInfo GetMethodInfoForNonGeneric()
+                {
+                    MethodInfo methodInfo = instance.Type.GetMethod(node.Method.Name, listOfArgumentsForNewMethod.Select(a => a.Type).ToArray());
+                    if (methodInfo.DeclaringType != instance.Type)
+                        methodInfo = methodInfo.DeclaringType.GetMethod(node.Method.Name, listOfArgumentsForNewMethod.Select(a => a.Type).ToArray());
+                    return methodInfo;
+                }
+            }
 
             MethodCallExpression GetStaticExpression()
                 => node.Method.IsGenericMethod
diff --git a/tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/ShouldUseDeclaringTypeForInstanceMethodCalls.cs b/tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/ShouldUseDeclaringTypeForInstanceMethodCalls.cs
new file mode 100644
index 0000000..6d6ecaf
--- /dev/null
+++ b/tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/ShouldUseDeclaringTypeForInstanceMethodCalls.cs
@@ -0,0 +1,83 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using Xunit;
+
+namespace AutoMapper.Extensions.ExpressionMapping.UnitTests
+{
+    public class ShouldUseDeclaringTypeForInstanceMethodCalls
+    {
+        [Fact]
+        public void MethodInfoShouldRetainDeclaringTypeInMappedExpression()
+        {
+            //Arrange
+            var config = new MapperConfiguration
+            (
+                cfg =>
+                {
+                    cfg.CreateMap<EntityModel, Entity>();
+                    cfg.CreateMap<Entity, EntityModel>();
+                }
+            );
+            config.AssertConfigurationIsValid();
+            var mapper = config.CreateMapper();
+            Expression<Func<Entity, bool>> filter = e => e.SimpleEnum.HasFlag(SimpleEnum.Value3);
+            EntityModel entityModel1 = new() { SimpleEnum = SimpleEnumModel.Value3 };
+            EntityModel entityModel2 = new() { SimpleEnum = SimpleEnumModel.Value2 };
+
+            //act
+            Expression<Func<EntityModel, bool>> mappedFilter = mapper.MapExpression<Expression<Func<EntityModel, bool>>>(filter);
+
+            //assert
+            Assert.Equal(typeof(Enum), HasFlagVisitor.GetasFlagReflectedType(mappedFilter));
+            Assert.Single(new List<EntityModel> { entityModel1 }.AsQueryable().Where(mappedFilter));
+            Assert.Empty(new List<EntityModel> { entityModel2 }.AsQueryable().Where(mappedFilter));
+        }
+
+        public enum SimpleEnum
+        {
+            Value1,
+            Value2,
+            Value3
+        }
+
+        public record Entity
+        {
+            public int Id { get; init; }
+            public SimpleEnum SimpleEnum { get; init; }
+        }
+
+        public enum SimpleEnumModel
+        {
+            Value1,
+            Value2,
+            Value3
+        }
+
+        public record EntityModel
+        {
+            public int Id { get; init; }
+            public SimpleEnumModel SimpleEnum { get; init; }
+        }
+
+        public class HasFlagVisitor : ExpressionVisitor
+        {
+            public static Type GetasFlagReflectedType(Expression expression)
+            {
+                HasFlagVisitor hasFlagVisitor = new();
+                hasFlagVisitor.Visit(expression);
+                return hasFlagVisitor.HasFlagReflectedType;
+            }
+            protected override Expression VisitMethodCall(MethodCallExpression node)
+            {
+                if (node.Method.Name == "HasFlag")
+                    HasFlagReflectedType = node.Method.ReflectedType;
+
+                return base.VisitMethodCall(node);
+            }
+
+            public Type HasFlagReflectedType { get; private set; }
+        }
+    }
+}