Fix #2165: DeclareVariables step must update ResolveResult annotation when using out var.

Author: siegfriedpammer

ICSharpCode.Decompiler.Tests/TestCases/Correctness/OverloadResolution.cs

@@ -42,6 +42,7 @@ static void Main()
 #endif
 			Issue2444.M2();
 			Issue2741.B.Test(new Issue2741.C());
+			ExtensionMethodDemo.Issue2165.Test();
 		}
 
 		#region ConstructorTest
@@ -550,3 +551,46 @@ public object this[int key] {
 		}
 	}
 }
+
+namespace ExtensionMethodDemo
+{
+	// First extension class with an out int parameter
+	public static class StringExtensions
+	{
+		public static bool TryParseCustom(this string input, out int result)
+		{
+			return int.TryParse(input, out result);
+		}
+	}
+
+	// Second extension class with an out double parameter
+	public static class StringDoubleExtensions
+	{
+		public static bool TryParseCustom(this string input, out double result)
+		{
+			return double.TryParse(input, out result);
+		}
+	}
+
+	class Issue2165
+	{
+		public static void Test()
+		{
+			string value1 = "123";
+			string value2 = "123.45";
+#if CS70
+			// Use the int version with extension method syntax
+			if (value1.TryParseCustom(out int intResult))
+			{
+				Console.WriteLine("Parsed int: " + intResult);
+			}
+
+			// Use the double version with extension method syntax
+			if (value2.TryParseCustom(out double doubleResult))
+			{
+				Console.WriteLine("Parsed double: " + doubleResult);
+			}
+#endif
+		}
+	}
+}

ICSharpCode.Decompiler/CSharp/Transforms/DeclareVariables.cs

@@ -622,13 +622,16 @@ void InsertVariableDeclarations(TransformContext context)
 				{
 					// 'T v; SomeCall(out v);' can be combined to 'SomeCall(out T v);'
 					AstType type;
+					bool isOutVar = false;
 					if (context.Settings.AnonymousTypes && v.Type.ContainsAnonymousType())
 					{
 						type = new SimpleType("var");
+						isOutVar = true;
 					}
 					else if (dirExpr.Annotation<UseImplicitlyTypedOutAnnotation>() != null)
 					{
 						type = new SimpleType("var");
+						isOutVar = true;
 					}
 					else
 					{
@@ -652,6 +655,11 @@ void InsertVariableDeclarations(TransformContext context)
 					var ovd = new OutVarDeclarationExpression(type, name);
 					ovd.Variable.AddAnnotation(new ILVariableResolveResult(ilVariable));
 					ovd.CopyAnnotationsFrom(dirExpr);
+					if (isOutVar)
+					{
+						ovd.RemoveAnnotations<ResolveResult>();
+						ovd.AddAnnotation(new OutVarResolveResult(v.Type));
+					}
 					replacements.Add((dirExpr, ovd));
 				}
 				else