Ambiguity in Roslyn's CompilationUnitSyntax.ReplaceNode

StackOverflow https://stackoverflow.com/questions/21948634

  •  14-10-2022
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Question

I'm trying to replace CompilationUnitSyntax of a class using Roslyn.

However, ReplaceNode that I'm using has a different signature than ReplaceNode in Roslyn FAQ and any StackOverflow question that I've looked at. Can anyone point out why is that, and how can I use ReplaceNode that takes old ClassDeclarationSyntax and new ClassDeclarationSyntax as parameters?

I'm looking at September CTP FAQ¹, method:

    [FAQ(26)]
    public void AddMethodToClass()

particularly the following line:

        CompilationUnitSyntax newCompilationUnit =
            compilationUnit.ReplaceNode(classDeclaration, newClassDeclaration);

When I'm attempting to build this code, I'm getting an error because ReplaceNode expects different arguments:

 'Roslyn.Compilers.CSharp.CompilationUnitSyntax' does not contain a definition for 'ReplaceNode' and the best extension method overload
 'Roslyn.Compilers.CSharp.SyntaxExtensions.ReplaceNode<TRoot>(TRoot,
 Roslyn.Compilers.CSharp.SyntaxNode,
 Roslyn.Compilers.SyntaxRemoveOptions,
 System.Func<Roslyn.Compilers.CSharp.SyntaxNode,Roslyn.Compilers.CSharp.SyntaxTriviaList>,
 System.Func<Roslyn.Compilers.CSharp.SyntaxNode,Roslyn.Compilers.CSharp.SyntaxTriviaList>)'

¹ I'm fairly sure I'm using the September CTP:

I'm using the FAQ from %userprofile%\Documents\Microsoft Roslyn CTP - September 2012\CSharp\APISampleUnitTestsCS\FAQ.cs

NuGet says that my Roslyn package has version 1.2.20906.2

Was it helpful?

Solution

There are two overloads of ReplaceNode() (both are extension methods):

  1. public static TRoot ReplaceNode<TRoot, TNode>(
    this TRoot root, TNode oldNode, TNode newNode)
    where TRoot : CommonSyntaxNode where TNode : CommonSyntaxNode;

    in Roslyn.Compilers.CommonSyntaxNodeExtensions.

  2. public static TRoot ReplaceNode<TRoot>(
    this TRoot root, SyntaxNode node, SyntaxRemoveOptions options, 
    Func<SyntaxNode, SyntaxTriviaList> keepLeadingTrivia = null,
    Func<SyntaxNode, SyntaxTriviaList> keepTrailingTrivia = null)
    where TRoot : SyntaxNode

    in Roslyn.Compilers.CSharp.SyntaxExtensions.

You want the first one, but the error message talks about the second one, which indicates that you're missing using Roslyn.Compilers;.

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