Conversion of parenthesized ref arguments no longer assigns back - fixes #1046

Author: GrahamTheCoder

CHANGELOG.md

@@ -9,7 +9,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 
 ### VB -> C#
+
 * Remove square brackets from identifiers [#1043](https://github.com/icsharpcode/CodeConverter/issues/1043)
+* Conversion of parenthesized ref arguments no longer assigns back [#1046](https://github.com/icsharpcode/CodeConverter/issues/1046)
 
 ### C# -> VB
 

CodeConverter/CSharp/ExpressionNodeVisitor.cs

@@ -1819,8 +1819,8 @@ private ArgumentSyntax CreateOptionalRefArg(IParameterSymbol p, RefKind refKind)
     private RefConversion NeedsVariableForArgument(VBasic.Syntax.ArgumentSyntax node, RefKind refKind)
     {
         if (refKind == RefKind.None) return RefConversion.Inline;
-        if (!(node is VBSyntax.SimpleArgumentSyntax sas)) return RefConversion.PreAssigment;
-        var expression = sas.Expression.SkipIntoParens();
+        if (!(node is VBSyntax.SimpleArgumentSyntax sas) || sas is { Expression: VBSyntax.ParenthesizedExpressionSyntax }) return RefConversion.PreAssigment;
+        var expression = sas.Expression;
 
         return GetRefConversion(expression);
 

Tests/CSharp/ExpressionTests/ByRefTests.cs

@@ -370,6 +370,44 @@ public void S([Optional] ref DateTime dt)
 }");
     }
 
+    [Fact]
+    public async Task ParenthesizedArgShouldNotBeAssignedBackAsync()
+    {
+        await TestConversionVisualBasicToCSharpAsync(@"
+Public Class C
+    Public Sub S()
+        Dim i As Integer = 0
+        Modify(i)
+        System.Diagnostics.Debug.Assert(i = 1)
+        Modify((i))
+        System.Diagnostics.Debug.Assert(i = 1)
+    End Sub
+
+    Sub Modify(ByRef i As Integer)
+        i = i + 1
+    End Sub
+End Class
+", @"using System.Diagnostics;
+
+public partial class C
+{
+    public void S()
+    {
+        int i = 0;
+        Modify(ref i);
+        Debug.Assert(i == 1);
+        int argi = i;
+        Modify(ref argi);
+        Debug.Assert(i == 1);
+    }
+
+    public void Modify(ref int i)
+    {
+        i = i + 1;
+    }
+}");
+    }
+
     [Fact]
     public async Task OutOptionalArgumentAsync()
     {