Fix non-string case regression - fixes #585

Author: GrahamTheCoder

CodeConverter/CSharp/MethodBodyExecutableStatementVisitor.cs

@@ -766,20 +766,26 @@ private CasePatternSwitchLabelSyntax WrapInCasePatternSwitchLabelSyntax(VBSyntax
                 patternMatch = ValidSyntaxFactory.VarPattern(varName);
                 ExpressionSyntax csLeft = SyntaxFactory.IdentifierName(varName), csRight = expression;
                 var caseTypeInfo = _semanticModel.GetTypeInfo(vbCase);
-                var vbEquality = CommonConversions.VisualBasicEqualityComparison;
-                if (vbEquality.GetObjectEqualityType(typeInfo, caseTypeInfo) == VisualBasicEqualityComparison.RequiredType.Object) {
-                    expression = vbEquality.GetFullExpressionForVbObjectComparison(csLeft, csRight);
-                } else {
+                expression = EqualsAdjustedForStringComparison(node, vbCase, typeInfo, csLeft, csRight, caseTypeInfo);
+            }
+
+            var colonToken = SyntaxFactory.Token(SyntaxKind.ColonToken);
+            return SyntaxFactory.CasePatternSwitchLabel(patternMatch, SyntaxFactory.WhenClause(expression), colonToken);
+        }
+
+        private ExpressionSyntax EqualsAdjustedForStringComparison(VBSyntax.SelectBlockSyntax node, VBSyntax.ExpressionSyntax vbCase, TypeInfo lhsTypeInfo, ExpressionSyntax csLeft, ExpressionSyntax csRight, TypeInfo rhsTypeInfo)
+        {
+            var vbEquality = CommonConversions.VisualBasicEqualityComparison;
+            switch (vbEquality.GetObjectEqualityType(lhsTypeInfo, rhsTypeInfo)) {
+                case VisualBasicEqualityComparison.RequiredType.Object:
+                    return vbEquality.GetFullExpressionForVbObjectComparison(csLeft, csRight);
+                case VisualBasicEqualityComparison.RequiredType.StringOnly:
                     // We know lhs isn't null, because we always coalesce it in the switch expression
                     (csLeft, csRight) = vbEquality
-                        .AdjustForVbStringComparison(node.SelectStatement.Expression, csLeft, typeInfo, true, vbCase, csRight, caseTypeInfo, false);
-                    expression = SyntaxFactory.BinaryExpression(SyntaxKind.EqualsExpression, csLeft, csRight);
-                }
+                        .AdjustForVbStringComparison(node.SelectStatement.Expression, csLeft, lhsTypeInfo, true, vbCase, csRight, rhsTypeInfo, false);
+                    break;
             }
-
-            var casePatternSwitchLabelSyntax = SyntaxFactory.CasePatternSwitchLabel(patternMatch,
-                SyntaxFactory.WhenClause(expression), SyntaxFactory.Token(SyntaxKind.ColonToken));
-            return casePatternSwitchLabelSyntax;
+            return SyntaxFactory.BinaryExpression(SyntaxKind.EqualsExpression, csLeft, csRight);
         }
 
         public override async Task<SyntaxList<StatementSyntax>> VisitWithBlock(VBSyntax.WithBlockSyntax node)

Tests/CSharp/StatementTests/StatementTests.cs

@@ -1972,5 +1972,50 @@ internal static string prtWhere(EWhere aWhere)
     }
 }");
         }
+
+        [Fact] //https://github.com/icsharpcode/CodeConverter/issues/585
+        public async Task Issue585_SwitchNonStringAsync()
+        {
+            await TestConversionVisualBasicToCSharpAsync(@"Imports System.Data
+
+Public Class NonStringSelect
+    Private Function Test3(CurRow As DataRow)
+        For Each CurCol As DataColumn In CurRow.GetColumnsInError
+            Select Case CurCol.DataType
+                Case GetType(String)
+                    Return False
+                Case Else
+                    Return True
+            End Select
+        Next
+    End Function
+End Class", @"using System.Data;
+
+public partial class NonStringSelect
+{
+    private object Test3(DataRow CurRow)
+    {
+        foreach (DataColumn CurCol in CurRow.GetColumnsInError())
+        {
+            switch (CurCol.DataType)
+            {
+                case var @case when @case == typeof(string):
+                    {
+                        return false;
+                    }
+
+                default:
+                    {
+                        return true;
+                    }
+            }
+        }
+
+        return default;
+    }
+}
+1 target compilation errors:
+CS0825: The contextual keyword 'var' may only appear within a local variable declaration or in script code");
+        }
     }
 }