C# -> VB: unchecked can cause compile error

從轉換錯誤中識別出的 CommonConversions.RemodelVariableDeclaration 開始，重現包含 unchecked 十六進位 Color.FromArgb 引數的 C# 輸入。追蹤這些運算式如何轉換為 VB，並驗證輸出與預期的 Dim 宣告相符且沒有轉換錯誤。

Input code

using System.Drawing;
using System.Windows.Forms;

class ConverterTests {
    public Color[] test1() {
        var textColor = Color.FromArgb(unchecked((int)0xFFCFCFCF));
        var backColor = Color.FromArgb(unchecked((int)0xFF303030));
        var altTextColor = Color.FromArgb(unchecked((int)0xFFFFFFFF));
        var altBackColor = Color.FromArgb(unchecked((int)0xFF515259));

        return new Color[] { textColor, backColor, altTextColor, altBackColor };
    }
}

Erroneous output

Imports System.Drawing
Imports System.Windows.Forms

Friend Class ConverterTests
    Public Function test1() As Color()
                ''' Cannot convert LocalDeclarationStatementSyntax, System.InvalidCastException: Unable to cast object of type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.EmptyStatementSyntax' to type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.ExpressionSyntax'.
'''    at ICSharpCode.CodeConverter.VB.CommonConversions.RemodelVariableDeclaration(VariableDeclarationSyntax declaration)
'''    at ICSharpCode.CodeConverter.VB.MethodBodyExecutableStatementVisitor.VisitLocalDeclarationStatement(LocalDeclarationStatementSyntax node)
'''    at Microsoft.CodeAnalysis.CSharp.Syntax.LocalDeclarationStatementSyntax.Accept[TResult](CSharpSyntaxVisitor`1 visitor)
'''    at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor`1.Visit(SyntaxNode node)
'''    at ICSharpCode.CodeConverter.VB.CommentConvertingMethodBodyVisitor.DefaultVisit(SyntaxNode node)
''' 
''' Input:
'''         var textColor = System.Drawing.Color.FromArgb(unchecked((int)0xFFCFCFCF));
''' 
''' 
                ''' Cannot convert LocalDeclarationStatementSyntax, System.InvalidCastException: Unable to cast object of type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.EmptyStatementSyntax' to type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.ExpressionSyntax'.
'''    at ICSharpCode.CodeConverter.VB.CommonConversions.RemodelVariableDeclaration(VariableDeclarationSyntax declaration)
'''    at ICSharpCode.CodeConverter.VB.MethodBodyExecutableStatementVisitor.VisitLocalDeclarationStatement(LocalDeclarationStatementSyntax node)
'''    at Microsoft.CodeAnalysis.CSharp.Syntax.LocalDeclarationStatementSyntax.Accept[TResult](CSharpSyntaxVisitor`1 visitor)
'''    at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor`1.Visit(SyntaxNode node)
'''    at ICSharpCode.CodeConverter.VB.CommentConvertingMethodBodyVisitor.DefaultVisit(SyntaxNode node)
''' 
''' Input:
'''         var backColor = System.Drawing.Color.FromArgb(unchecked((int)0xFF303030));
''' 
''' 
                ''' Cannot convert LocalDeclarationStatementSyntax, System.InvalidCastException: Unable to cast object of type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.EmptyStatementSyntax' to type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.ExpressionSyntax'.
'''    at ICSharpCode.CodeConverter.VB.CommonConversions.RemodelVariableDeclaration(VariableDeclarationSyntax declaration)
'''    at ICSharpCode.CodeConverter.VB.MethodBodyExecutableStatementVisitor.VisitLocalDeclarationStatement(LocalDeclarationStatementSyntax node)
'''    at Microsoft.CodeAnalysis.CSharp.Syntax.LocalDeclarationStatementSyntax.Accept[TResult](CSharpSyntaxVisitor`1 visitor)
'''    at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor`1.Visit(SyntaxNode node)
'''    at ICSharpCode.CodeConverter.VB.CommentConvertingMethodBodyVisitor.DefaultVisit(SyntaxNode node)
''' 
''' Input:
'''         var altTextColor = System.Drawing.Color.FromArgb(unchecked((int)0xFFFFFFFF));
''' 
''' 
                ''' Cannot convert LocalDeclarationStatementSyntax, System.InvalidCastException: Unable to cast object of type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.EmptyStatementSyntax' to type 'Microsoft.CodeAnalysis.VisualBasic.Syntax.ExpressionSyntax'.
'''    at ICSharpCode.CodeConverter.VB.CommonConversions.RemodelVariableDeclaration(VariableDeclarationSyntax declaration)
'''    at ICSharpCode.CodeConverter.VB.MethodBodyExecutableStatementVisitor.VisitLocalDeclarationStatement(LocalDeclarationStatementSyntax node)
'''    at Microsoft.CodeAnalysis.CSharp.Syntax.LocalDeclarationStatementSyntax.Accept[TResult](CSharpSyntaxVisitor`1 visitor)
'''    at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxVisitor`1.Visit(SyntaxNode node)
'''    at ICSharpCode.CodeConverter.VB.CommentConvertingMethodBodyVisitor.DefaultVisit(SyntaxNode node)
''' 
''' Input:
'''         var altBackColor = System.Drawing.Color.FromArgb(unchecked((int)0xFF515259));
''' 
''' 

        Return New Color() {textColor, backColor, altTextColor, altBackColor}
    End Function
End Class

Expected output

Imports System.Drawing
Imports System.Windows.Forms

Friend Class ConverterTests
    Public Function test1() As Color()
        Dim textColor As Color = Color.FromArgb(&HFFCFCFCF)
        Dim backColor As Color = Color.FromArgb(&HFF303030)
        Dim altTextColor As Color = Color.FromArgb(&HFFFFFFFF)
        Dim altBackColor As Color = Color.FromArgb(&HFF515259)

        Return New Color() {textColor, backColor, altTextColor, altBackColor}
    End Function
End Class

Details

• Product in use: VS extension (Microsoft Visual Studio Community 2019 / Version 16.11.23)
• Version in use: 9.1.1.0
• Did you see it working in a previous version, which? / No, but I don't think I've tried this code before
• I suppose this is fairly minor, fixing the output is easy, but I noticed it when converting a fairly large file, so I suppose it's probably a good idea to fix. I'm happy to help, but not sure I'd be able to figure anything out - this project looks fairly huge...