Add AsEnumerable in linq "in" clause - fixes #544

Author: GrahamTheCoder

CHANGELOG.md

@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### VB -> C#
 * Optimize away some redundant casts and conversions with strings/chars - [#388](https://github.com/icsharpcode/CodeConverter/issues/388)
 * Improve performance of single file conversion
+* Add AsEnumerable where needed in linq "in" clause - [#544](https://github.com/icsharpcode/CodeConverter/issues/544)
 
 ### C# -> VB
 

CodeConverter/CSharp/ExpressionNodeVisitor.cs

@@ -52,7 +52,7 @@ public ExpressionNodeVisitor(SemanticModel semanticModel,
             _lambdaConverter = new LambdaConverter(commonConversions, semanticModel);
             _visualBasicEqualityComparison = visualBasicEqualityComparison;
             TriviaConvertingExpressionVisitor = new CommentConvertingVisitorWrapper(this, _semanticModel.SyntaxTree);
-            _queryConverter = new QueryConverter(commonConversions, TriviaConvertingExpressionVisitor);
+            _queryConverter = new QueryConverter(commonConversions, _semanticModel, TriviaConvertingExpressionVisitor);
             _csCompilation = csCompilation;
             _typeContext = typeContext;
             _extraUsingDirectives = extraUsingDirectives;

CodeConverter/CSharp/MethodBodyExecutableStatementVisitor.cs

@@ -598,8 +598,8 @@ public override async Task<SyntaxList<StatementSyntax>> VisitForEachBlock(VBSynt
                 id = declaration.Variables.Single().Identifier;
             } else if (_semanticModel.GetSymbolInfo(stmt.ControlVariable).Symbol is ISymbol varSymbol) {
                 var variableType = varSymbol.GetSymbolType();
-                var useVar = variableType?.SpecialType == SpecialType.System_Object || _semanticModel.GetTypeInfo(stmt.Expression).ConvertedType.IsEnumerableOfExactType(variableType);
-                type = CommonConversions.GetTypeSyntax(varSymbol.GetSymbolType(), useVar);
+                var explicitCastWouldHaveNoEffect = variableType?.SpecialType == SpecialType.System_Object || _semanticModel.GetTypeInfo(stmt.Expression).ConvertedType.IsEnumerableOfExactType(variableType);
+                type = CommonConversions.GetTypeSyntax(varSymbol.GetSymbolType(), explicitCastWouldHaveNoEffect);
                 var v = (IdentifierNameSyntax)await stmt.ControlVariable.AcceptAsync(_expressionVisitor);
                 if (_localsToInlineInLoop.Contains(varSymbol)) {
                     id = v.Identifier;

CodeConverter/CSharp/QueryConverter.cs

@@ -6,6 +6,7 @@
 using ICSharpCode.CodeConverter.Util;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.Operations;
 using Microsoft.CodeAnalysis.VisualBasic.Syntax;
 using CSSyntax = Microsoft.CodeAnalysis.CSharp.Syntax;
 using VBSyntax = Microsoft.CodeAnalysis.VisualBasic.Syntax;
@@ -18,11 +19,13 @@ namespace ICSharpCode.CodeConverter.CSharp
     internal class QueryConverter
     {
         private readonly CommentConvertingVisitorWrapper _triviaConvertingVisitor;
+        private SemanticModel _semanticModel;
 
-        public QueryConverter(CommonConversions commonConversions, CommentConvertingVisitorWrapper triviaConvertingVisitor)
+        public QueryConverter(CommonConversions commonConversions, SemanticModel semanticModel, CommentConvertingVisitorWrapper triviaConvertingExpressionVisitor)
         {
             CommonConversions = commonConversions;
-            _triviaConvertingVisitor = triviaConvertingVisitor;
+            _semanticModel = semanticModel;
+            _triviaConvertingVisitor = triviaConvertingExpressionVisitor;
         }
 
         private CommonConversions CommonConversions { get; }
@@ -239,9 +242,15 @@ private static bool RequiredContinuation(VBSyntax.QueryClauseSyntax queryClauseS
         private async Task<CSSyntax.FromClauseSyntax> ConvertFromClauseSyntaxAsync(VBSyntax.FromClauseSyntax vbFromClause)
         {
             var collectionRangeVariableSyntax = vbFromClause.Variables.Single();
+            var expression = (CSSyntax.ExpressionSyntax)await collectionRangeVariableSyntax.Expression.AcceptAsync(_triviaConvertingVisitor);
+            var parentOperation = _semanticModel.GetOperation(collectionRangeVariableSyntax.Expression)?.Parent;
+            if (parentOperation.IsImplicit && parentOperation is IInvocationOperation io &&
+                io.TargetMethod.MethodKind == MethodKind.ReducedExtension && io.TargetMethod.Name == nameof(Enumerable.AsEnumerable)) {
+                expression = SyntaxFactory.InvocationExpression(ValidSyntaxFactory.MemberAccess(expression, io.TargetMethod.Name), SyntaxFactory.ArgumentList());
+            }
             var fromClauseSyntax = SyntaxFactory.FromClause(
                 CommonConversions.ConvertIdentifier(collectionRangeVariableSyntax.Identifier.Identifier),
-                (CSSyntax.ExpressionSyntax) await collectionRangeVariableSyntax.Expression.AcceptAsync(_triviaConvertingVisitor));
+                expression);
             return fromClauseSyntax;
         }
 

CodeConverter/Shared/DefaultReferences.cs

@@ -24,6 +24,7 @@ public class DefaultReferences
             typeof(System.ComponentModel.BrowsableAttribute),
             typeof(System.Dynamic.DynamicObject),
             typeof(System.Data.DataRow),
+            typeof(System.Data.DataTableExtensions),
             typeof(System.Net.Http.HttpClient),
             typeof(System.Web.HttpUtility),
             typeof(System.Xml.XmlElement),

Tests/CSharp/ExpressionTests/LinqExpressionTests.cs

@@ -188,6 +188,35 @@ Return String.Empty
 }");
         }
 
+        [Fact]
+        public async Task LinqAsEnumerable()
+        {
+            await TestConversionVisualBasicToCSharpAsync(@"Imports System.Data
+
+Public Class AsEnumerableTest
+    Public Sub FillImgColor()
+        Dim dtsMain As New DataSet
+        For Each i_ColCode As Integer In 
+            From CurRow In dtsMain.Tables(""tb_Color"") Select CInt(CurRow.Item(""i_ColCode""))
+        Next
+    End Sub
+End Class", @"using System.Data;
+using System.Linq;
+using Microsoft.VisualBasic.CompilerServices; // Install-Package Microsoft.VisualBasic
+
+public partial class AsEnumerableTest
+{
+    public void FillImgColor()
+    {
+        var dtsMain = new DataSet();
+        foreach (int i_ColCode in from CurRow in dtsMain.Tables[""tb_Color""].AsEnumerable()
+                                  select Conversions.ToInteger(CurRow[""i_ColCode""]))
+        {
+        }
+    }
+}");
+        }
+
         [Fact]
         public async Task LinqMultipleFromsAsync()
         {

Vsix/Vsix.csproj

@@ -59,6 +59,12 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
+    <PackageReference Include="System.Data.Common">
+      <Version>4.3.0</Version>
+    </PackageReference>
+    <PackageReference Include="System.Data.DataSetExtensions">
+      <Version>4.5.0</Version>
+    </PackageReference>
     <PackageReference Include="System.Data.SqlClient">
       <Version>4.8.1</Version>
     </PackageReference>
@@ -95,7 +101,6 @@
     <Reference Include="PresentationCore" />
     <Reference Include="PresentationFramework" />
     <Reference Include="System" />
-    <Reference Include="System.Data" />
     <Reference Include="System.Design" />
     <Reference Include="System.Web" />
     <Reference Include="System.Windows.Forms" />