using Microsoft.CodeAnalysis;

using Microsoft.CodeAnalysis.CSharp;

using Microsoft.CodeAnalysis.CSharp.Syntax;

using System;

using System.Collections.Generic;

using System.Diagnostics.CodeAnalysis;

using System.IO;

using static Globals;

​

tree = CSharpSyntaxTree.ParseText(@"

using System;

​

namespace TopLevel

{

  class Bar {

    public void test1(){}

​

    public void test2(){ Console.WriteLine(""str""); }

​

    public void Fizz() {

      Console.WriteLine(test1());

      Console.WriteLine(test1(test2()));

      test2();

    }

  }

}");

compilation = CSharpCompilation.Create("HelloWorld").AddSyntaxTrees(tree);

model = compilation.GetSemanticModel(tree);

new Finder().Visit(tree.GetRoot());

Console.WriteLine(new Rewriter().Visit(tree.GetRoot()).NormalizeWhitespace().ToFullString());

​

public static class Globals

{

    public static SyntaxTree tree;

    public static CompilationUnitSyntax root;

    public static CSharpCompilation compilation;

    public static SemanticModel model;

    public static Dictionary<IMethodSymbol, string> renames = new();

}

​

public sealed class Finder : CSharpSyntaxWalker

{

    public override void VisitMethodDeclaration(MethodDeclarationSyntax node)

    {

        base.VisitMethodDeclaration(node);

        renames.Add(model.GetDeclaredSymbol(node), "prefix_" + node.Identifier.Value);

    }

}

​

public sealed class Rewriter : CSharpSyntaxRewriter

{

    public override SyntaxNode VisitMethodDeclaration(MethodDeclarationSyntax mds)

    {

        IMethodSymbol symbol = model.GetDeclaredSymbol(mds);

        mds = (MethodDeclarationSyntax)base.VisitMethodDeclaration(mds);

        if (renames.TryGetValue(symbol, out string newName))

            mds = mds.ReplaceToken(mds.Identifier, SyntaxFactory.Identifier(newName));

        return mds;

    }

​

    [return: NotNullIfNotNull("node")]

    public override SyntaxNode Visit(SyntaxNode node)

    {

        node = base.Visit(node);

        if (node is SimpleNameSyntax sns &&

            model.GetSymbolInfo(sns) is { Symbol: IMethodSymbol ms } && renames.TryGetValue(ms, out string newName)

        )

            node = sns.ReplaceToken(sns.Identifier, SyntaxFactory.Identifier(newName));

        return node;

    }

}