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Fix VB -> C# char comparison with empty string #1240

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Fix VB -> C# char comparison with empty string #1240

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19 changes: 16 additions & 3 deletions CodeConverter/CSharp/BinaryExpressionConverter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -82,11 +82,24 @@ private async Task<CSharpSyntaxNode> ConvertBinaryExpressionAsync(VBasic.Syntax.
case VisualBasicEqualityComparison.RequiredType.StringOnly:
if (lhsTypeInfo.ConvertedType?.SpecialType == SpecialType.System_String &&
rhsTypeInfo.ConvertedType?.SpecialType == SpecialType.System_String &&
_visualBasicEqualityComparison.TryConvertToNullOrEmptyCheck(node, lhs, rhs, out CSharpSyntaxNode visitBinaryExpression)) {
_visualBasicEqualityComparison.TryConvertToNullOrEmptyCheck(node, lhs, rhs, lhsTypeInfo, rhsTypeInfo, out CSharpSyntaxNode visitBinaryExpression)) {
return visitBinaryExpression;
}
(lhs, rhs) = _visualBasicEqualityComparison.AdjustForVbStringComparison(node.Left, lhs, lhsTypeInfo, false, node.Right, rhs, rhsTypeInfo, false);
omitConversion = true; // Already handled within for the appropriate types (rhs can become int in comparison)
if (lhsTypeInfo.Type?.SpecialType == SpecialType.System_Char && rhsTypeInfo.Type?.SpecialType == SpecialType.System_Char) {
// Do nothing, char comparison
} else if ((lhsTypeInfo.Type?.SpecialType == SpecialType.System_Char && rhsTypeInfo.Type?.SpecialType == SpecialType.System_String && _visualBasicEqualityComparison.IsNothingOrEmpty(node.Right)) ||
(rhsTypeInfo.Type?.SpecialType == SpecialType.System_Char && lhsTypeInfo.Type?.SpecialType == SpecialType.System_String && _visualBasicEqualityComparison.IsNothingOrEmpty(node.Left))) {
if (lhsTypeInfo.Type?.SpecialType == SpecialType.System_Char) {
rhs = CS.SyntaxFactory.MemberAccessExpression(CS.SyntaxKind.SimpleMemberAccessExpression, CS.SyntaxFactory.PredefinedType(CS.SyntaxFactory.Token(CS.SyntaxKind.CharKeyword)), CS.SyntaxFactory.IdentifierName("MinValue"));
omitConversion = true;
} else {
lhs = CS.SyntaxFactory.MemberAccessExpression(CS.SyntaxKind.SimpleMemberAccessExpression, CS.SyntaxFactory.PredefinedType(CS.SyntaxFactory.Token(CS.SyntaxKind.CharKeyword)), CS.SyntaxFactory.IdentifierName("MinValue"));
omitConversion = true;
}
} else {
(lhs, rhs) = _visualBasicEqualityComparison.AdjustForVbStringComparison(node.Left, lhs, lhsTypeInfo, false, node.Right, rhs, rhsTypeInfo, false);
omitConversion = true; // Already handled within for the appropriate types (rhs can become int in comparison)
}
break;
case VisualBasicEqualityComparison.RequiredType.Object:
return _visualBasicEqualityComparison.GetFullExpressionForVbObjectComparison(lhs, rhs, VisualBasicEqualityComparison.ComparisonKind.Equals, node.IsKind(VBasic.SyntaxKind.NotEqualsExpression));
Expand Down
11 changes: 9 additions & 2 deletions CodeConverter/CSharp/VisualBasicEqualityComparison.cs
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Expand Up @@ -79,6 +79,7 @@ public RequiredType GetObjectEqualityType(params TypeInfo[] typeInfos)

if (typeInfos.All(
t => t.Type == null || t.Type.SpecialType == SpecialType.System_String ||
t.Type.SpecialType == SpecialType.System_Char ||
t.Type.IsArrayOf(SpecialType.System_Char) ) ) {
return RequiredType.StringOnly;
}
Expand Down Expand Up @@ -177,7 +178,7 @@ private static ObjectCreationExpressionSyntax NewStringFromArg(ExpressionSyntax
}

public bool TryConvertToNullOrEmptyCheck(VBSyntax.BinaryExpressionSyntax node, ExpressionSyntax lhs,
ExpressionSyntax rhs, out CSharpSyntaxNode? visitBinaryExpression)
ExpressionSyntax rhs, TypeInfo lhsTypeInfo, TypeInfo rhsTypeInfo, out CSharpSyntaxNode? visitBinaryExpression)
{
if (OptionCompareTextCaseInsensitive)
{
Expand All @@ -191,6 +192,12 @@ public bool TryConvertToNullOrEmptyCheck(VBSyntax.BinaryExpressionSyntax node, E
if (lhsEmpty || rhsEmpty)
{
var arg = lhsEmpty ? rhs : lhs;
var argType = lhsEmpty ? rhsTypeInfo : lhsTypeInfo;
if (argType.Type?.SpecialType != SpecialType.System_String && argType.Type?.SpecialType != SpecialType.System_Object) {
visitBinaryExpression = null;
return false;
}

var nullOrEmpty = SyntaxFactory.InvocationExpression(
SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.StringKeyword)),
Expand All @@ -207,7 +214,7 @@ public bool TryConvertToNullOrEmptyCheck(VBSyntax.BinaryExpressionSyntax node, E
return false;
}

private bool IsNothingOrEmpty(VBSyntax.ExpressionSyntax expressionSyntax)
public bool IsNothingOrEmpty(VBSyntax.ExpressionSyntax expressionSyntax)
{
expressionSyntax = expressionSyntax.SkipIntoParens();

Expand Down
9 changes: 9 additions & 0 deletions Program.vb
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
Imports System

Module Program
Sub Main()
Dim testChar As Char = Nothing
Dim testResult = testChar = ""
Console.WriteLine(testResult)
End Sub
End Module
12 changes: 12 additions & 0 deletions TestDotNet/Program.vb
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
Imports System

Module Program
Sub Main()
Dim testChar As Char = Nothing
Dim testResult = testChar = ""
Console.WriteLine(testResult)

Dim testResult2 = "" = testChar
Console.WriteLine(testResult2)
End Sub
End Module
6 changes: 6 additions & 0 deletions TestDotNet/TestDotNet.vbproj
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net8.0</TargetFramework>
</PropertyGroup>
</Project>
8 changes: 8 additions & 0 deletions TestEquality.csproj
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
</PropertyGroup>

</Project>
21 changes: 21 additions & 0 deletions Tests/CSharp/ExpressionTests/StringExpressionTests.cs
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Expand Up @@ -541,6 +541,27 @@ public void Foo()
{
string x = Conversions.ToString(DateTime.Parse(""2022-01-01"")) + "" 15:00"";
}
}");
}

[Fact]
public async Task CharEqualityEmptyStringAsync()
{
await TestConversionVisualBasicToCSharpAsync(@"Class TestClass
Private Sub TestMethod()
Dim testChar As Char = Nothing
Dim testResult = testChar = """"
Dim testResult2 = """" = testChar
End Sub
End Class", @"
internal partial class TestClass
{
private void TestMethod()
{
char testChar = default;
bool testResult = testChar == char.MinValue;
bool testResult2 = char.MinValue == testChar;
}
}");
}
}
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