[CodeIssues] Fix handling of member references in AssignmentMadeToSameVariableIssue.

ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/AssignmentMadeToSameVariableIssue.cs

@@ -29,6 +29,7 @@ using System.Collections.Generic;
 using ICSharpCode.NRefactory.Semantics;
 using ICSharpCode.NRefactory.TypeSystem;
 using ICSharpCode.NRefactory.PatternMatching;
+using System.Linq;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -62,14 +63,9 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 				var resolveResult = ctx.Resolve (assignmentExpression.Left);
 				var memberResolveResult = resolveResult as MemberResolveResult;
 				if (memberResolveResult != null) {
-					if (!(memberResolveResult.Member is IField))
+					var memberResolveResult2 = ctx.Resolve (assignmentExpression.Right) as MemberResolveResult;
+					if (memberResolveResult2 == null || !AreEquivalent(memberResolveResult, memberResolveResult2))
 						return;
-					if (!assignmentExpression.Left.Match (assignmentExpression.Right).Success) {
-						// in case: this.field = field
-						var memberResolveResult2 = ctx.Resolve (assignmentExpression.Right) as MemberResolveResult;
-						if (memberResolveResult2 == null || memberResolveResult.Member != memberResolveResult2.Member)
-							return;
-					}
 				} else if (resolveResult is LocalResolveResult) {
 					if (!assignmentExpression.Left.Match (assignmentExpression.Right).Success)
 						return;
@@ -89,6 +85,14 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 				AddIssue (node, ctx.TranslateString ("CS1717:Assignment made to same variable"),
 					new [] { new CodeAction (ctx.TranslateString ("Remove assignment"), action) });
 			}
+
+			static bool AreEquivalent(ResolveResult first, ResolveResult second)
+			{
+				var firstPath = InitializerPath.FromResolveResult(first);
+				var secondPath = InitializerPath.FromResolveResult(second);
+				return firstPath != null && firstPath.Equals(secondPath) && !firstPath.MemberPath.Any(m => !(m is IField)) &&
+					(firstPath.MemberRoot == null || firstPath.MemberRoot is IField);
+			}
 		}
 	}
 }

ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/AssignmentMadeToSameVariableIssueTests.cs

@@ -127,7 +127,7 @@ class TestClass
 }";
 			Test<AssignmentMadeToSameVariableIssue> (input, 2, output);
 		}
-
+		
 		[Test]
 		public void TestNoIssue ()
 		{
@@ -146,6 +146,69 @@ class TestClass
 		this.a = a;
 		Prop = Prop;
 	}
+}";
+			Test<AssignmentMadeToSameVariableIssue> (input, 0);
+		}
+		
+		[Test]
+		public void IgnoresAssignmentWithDifferentRootObjects ()
+		{
+			var input = @"
+class TestClass
+{
+	int a;
+
+	void TestMethod (TestClass tc)
+	{
+		a = tc.a;
+	}
+}";
+			Test<AssignmentMadeToSameVariableIssue> (input, 0);
+		}
+		
+		[Test]
+		public void NestedFieldAccess ()
+		{
+			var input = @"
+class TestClass
+{
+	int a;
+
+	TestClass nested;
+
+	void TestMethod ()
+	{
+		nested.nested.a = nested.nested.a;
+	}
+}";
+			var output = @"
+class TestClass
+{
+	int a;
+
+	TestClass nested;
+
+	void TestMethod ()
+	{
+	}
+}";
+			Test<AssignmentMadeToSameVariableIssue> (input, 1, output);
+		}
+		
+		[Test]
+		public void NestedPropertyAccess ()
+		{
+			var input = @"
+class TestClass
+{
+	int a;
+
+	TestClass nested { get; set; }
+
+	void TestMethod ()
+	{
+		nested.nested.a = nested.nested.a;
+	}
 }";
 			Test<AssignmentMadeToSameVariableIssue> (input, 0);
 		}