From 8d211e143cb589ab626b80cbe77c5301c3b8a5d6 Mon Sep 17 00:00:00 2001
From: GrahamTheCoder <GrahamTheCoder@gmail.com>
Date: Sun, 9 Jul 2023 17:50:57 +0100
Subject: [PATCH] Pay attention to lambda expressions - fixes #930

Inspired by https://github.com/JosefPihrt/Roslynator/blob/7ba2f29f5090aa13f4dd6b7936af55180b678333/src/CSharp/CSharp/Extensions/SyntaxExtensions.cs#L3114
---
 CodeConverter/CSharp/CommonConversions.cs     |  2 +
 CodeConverter/CSharp/ExpressionNodeVisitor.cs | 59 +++++++++++++++----
 2 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/CodeConverter/CSharp/CommonConversions.cs b/CodeConverter/CSharp/CommonConversions.cs
index d8545e15e..8564a8f3b 100644
--- a/CodeConverter/CSharp/CommonConversions.cs
+++ b/CodeConverter/CSharp/CommonConversions.cs
@@ -19,6 +19,7 @@ namespace ICSharpCode.CodeConverter.CSharp;
 
 internal class CommonConversions
 {
+    public ITypeSymbol System_Linq_Expressions_Expression_T { get; }
     private static readonly Type ExtensionAttributeType = typeof(ExtensionAttribute);
     public Document Document { get; }
     public SemanticModel SemanticModel { get; }
@@ -47,6 +48,7 @@ public CommonConversions(Document document, SemanticModel semanticModel,
         _typeContext = typeContext;
         VisualBasicEqualityComparison = visualBasicEqualityComparison;
         WinformsConversions = new WinformsConversions(typeContext);
+        System_Linq_Expressions_Expression_T = semanticModel.Compilation.GetTypeByMetadataName("System.Linq.Expressions.Expression`1");
     }
 
     public record VariablePair(CSSyntax.VariableDeclaratorSyntax CsVar, VBSyntax.ModifiedIdentifierSyntax VbVar);
diff --git a/CodeConverter/CSharp/ExpressionNodeVisitor.cs b/CodeConverter/CSharp/ExpressionNodeVisitor.cs
index 6f82e78f2..5647bef1a 100644
--- a/CodeConverter/CSharp/ExpressionNodeVisitor.cs
+++ b/CodeConverter/CSharp/ExpressionNodeVisitor.cs
@@ -1231,29 +1231,64 @@ private static bool NextStatementDefinitelyExecutedAfter(VBSyntax.InvocationExpr
 
     public override async Task<CSharpSyntaxNode> VisitSingleLineLambdaExpression(VBasic.Syntax.SingleLineLambdaExpressionSyntax node)
     {
-        IReadOnlyCollection<StatementSyntax> convertedStatements;
-        if (node.Body is VBasic.Syntax.StatementSyntax statement) {
-            convertedStatements = await ConvertMethodBodyStatementsAsync(statement, statement.Yield().ToArray());
-        } else {
-            var csNode = await node.Body.AcceptAsync<ExpressionSyntax>(TriviaConvertingExpressionVisitor);
-            convertedStatements = new[] { SyntaxFactory.ExpressionStatement(csNode)};
+        var originalIsWithinQuery = TriviaConvertingExpressionVisitor.IsWithinQuery;
+        TriviaConvertingExpressionVisitor.IsWithinQuery = IsLinqExpression(node);
+        try {
+            return await ConvertInnerAsync();
+        } finally {
+            TriviaConvertingExpressionVisitor.IsWithinQuery = originalIsWithinQuery;
+        }
+
+        async Task<CSharpSyntaxNode> ConvertInnerAsync()
+        {
+            IReadOnlyCollection<StatementSyntax> convertedStatements;
+            if (node.Body is VBasic.Syntax.StatementSyntax statement)
+            {
+                convertedStatements = await ConvertMethodBodyStatementsAsync(statement, statement.Yield().ToArray());
+            }
+            else
+            {
+                var csNode = await node.Body.AcceptAsync<ExpressionSyntax>(TriviaConvertingExpressionVisitor);
+                convertedStatements = new[] {SyntaxFactory.ExpressionStatement(csNode)};
+            }
+
+            var param = await node.SubOrFunctionHeader.ParameterList.AcceptAsync<ParameterListSyntax>(TriviaConvertingExpressionVisitor);
+            return await _lambdaConverter.ConvertAsync(node, param, convertedStatements);
         }
-        var param = await node.SubOrFunctionHeader.ParameterList.AcceptAsync<ParameterListSyntax>(TriviaConvertingExpressionVisitor);
-        return await _lambdaConverter.ConvertAsync(node, param, convertedStatements);
     }
 
     public override async Task<CSharpSyntaxNode> VisitMultiLineLambdaExpression(VBasic.Syntax.MultiLineLambdaExpressionSyntax node)
     {
-        var body = await ConvertMethodBodyStatementsAsync(node, node.Statements);
-        var param = await node.SubOrFunctionHeader.ParameterList.AcceptAsync<ParameterListSyntax>(TriviaConvertingExpressionVisitor);
-        return await _lambdaConverter.ConvertAsync(node, param, body.ToList());
+        var originalIsWithinQuery = TriviaConvertingExpressionVisitor.IsWithinQuery;
+        TriviaConvertingExpressionVisitor.IsWithinQuery = IsLinqExpression(node);
+        try {
+            return await ConvertInnerAsync();
+        } finally {
+            TriviaConvertingExpressionVisitor.IsWithinQuery = originalIsWithinQuery;
+        }
+
+        async Task<CSharpSyntaxNode> ConvertInnerAsync()
+        {
+            var body = await ConvertMethodBodyStatementsAsync(node, node.Statements);
+            var param = await node.SubOrFunctionHeader.ParameterList.AcceptAsync<ParameterListSyntax>(TriviaConvertingExpressionVisitor);
+            return await _lambdaConverter.ConvertAsync(node, param, body.ToList());
+        }
+    }
+
+    private bool IsLinqExpression(VisualBasicSyntaxNode node)
+    {
+        var convertedType = _semanticModel.GetTypeInfo(node).ConvertedType;
+        if (CommonConversions.System_Linq_Expressions_Expression_T.Equals(convertedType?.OriginalDefinition, SymbolEqualityComparer.Default)) {
+            return true;
+        }
+
+        return false;
     }
 
     public async Task<IReadOnlyCollection<StatementSyntax>> ConvertMethodBodyStatementsAsync(VBasic.VisualBasicSyntaxNode node, IReadOnlyCollection<VBSyntax.StatementSyntax> statements, bool isIterator = false, IdentifierNameSyntax csReturnVariable = null)
     {
 
         var innerMethodBodyVisitor = await MethodBodyExecutableStatementVisitor.CreateAsync(node, _semanticModel, TriviaConvertingExpressionVisitor, CommonConversions, _withBlockLhs, _extraUsingDirectives, _typeContext, isIterator, csReturnVariable);
-
         return await GetWithConvertedGotosOrNull(statements) ?? await ConvertStatements(statements);
 
         async Task<List<StatementSyntax>> ConvertStatements(IEnumerable<VBSyntax.StatementSyntax> readOnlyCollection)