在以下情况下，我试图以最简单、最直接的方式可靠地比较ITypeSymbol的两个实例（我在一个更大的项目中遇到了这些问题，并试图尽可能简化它）：
我有一个CSharpCompilation与这个SyntaxTree:
namespace MyAssembly
{
public class Foo
{
public Foo(Foo x)
{
}
}
}
我们正在使用CSharpSyntaxRewriter遍历树，更改类并更新Compilation。在第一次运行中，我们记住了第一个构造函数参数的ITypeSymbol（在本例中是类本身的类型）。更新编译后，我们将再次调用相同的重写器，并第二次从构造函数参数中获取ITypeSymbol。之后，我比较了两个ITypeSymbol，我希望它们表示相同的类型MyAssembly.Foo。
我的第一个比较方法只是调用ITypeSymbol.Equals()方法，但它返回false。它基本上返回false，因为在此期间我们更改了编译并获得了新的SemanticModel。如果我们不这样做，Equals（）方法实际上会返回true。
比较DeclaringSyntaxReferences（如本文所述如何比较Roslyn不同项目的类型符号（ITypeSymbol）？）返回false，因为在此期间我们更改了类Foo本身。如果构造函数参数的类型为Bar，并且我们重写了Bar，则行为将是相同的。要验证这一点，只需取消注释行
//RewriteBar(rewriter, compilation, resultTree);
并将代码样本中的构造函数参数类型替换为CCD_ 14。
结论：ITypeSymbol.Equals()不适用于新的编译和语义模型，并且将DeclaringSyntaxReferences与我们在此期间更改的类型进行比较也不适用。（我还用一种类型的外部程序集测试了这种行为——在这种情况下，ITypeSymbol.Equals（）对我有效。）
所以我的问题是：
- 在所描述的情况下，比较类型的预期方法是什么
- 有没有一个包罗万象的解决方案，或者我必须混合/组合不同的方法来确定类型相等（可能还采用完全限定名称的字符串表示考虑在内）
这是完整的测试程序，这个问题对我来说是可复制的。只需复制，包括Roslyn参考并执行：
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
namespace Demo.TypeSymbol
{
class Program
{
static void Main(string[] args)
{
var compilation = (CSharpCompilation) GetTestCompilation();
var rewriter = new Rewriter(changeSomething: true);
var tree = compilation.SyntaxTrees.First(); //first SyntaxTree is the one of class MyAssembly.Foo
rewriter.Model = compilation.GetSemanticModel (tree);
//first rewrite run
var resultTree = rewriter.Visit (tree.GetRoot()).SyntaxTree;
compilation = UpdateIfNecessary (compilation, rewriter, tree, resultTree);
rewriter.Model = compilation.GetSemanticModel (resultTree);
//just for demonstration; comment in to test behaviour when we are rewriting the class Bar -> in this case use Bar as constructor parameter in Foo
//RewriteBar(rewriter, compilation, resultTree);
//second rewrite run
rewriter.Visit (resultTree.GetRoot());
//now we want to compare the types...
Console.WriteLine(rewriter.ParameterTypeFirstRun);
Console.WriteLine(rewriter.ParameterTypeSecondRun);
//=> types are *not* equal
var typesAreEqual = rewriter.ParameterTypeFirstRun.Equals (rewriter.ParameterTypeSecondRun);
Console.WriteLine("typesAreEqual: " + typesAreEqual);
//=> syntax references are not equal
if(rewriter.ParameterTypeFirstRun.DeclaringSyntaxReferences.Any())
{
var syntaxReferencesAreEqual =
rewriter.ParameterTypeFirstRun.DeclaringSyntaxReferences.First()
.Equals(rewriter.ParameterTypeSecondRun.DeclaringSyntaxReferences.First());
Console.WriteLine("syntaxReferencesAreEqual: " + syntaxReferencesAreEqual);
}
//==> other options??
}
private static CSharpCompilation UpdateIfNecessary(CSharpCompilation compilation, Rewriter rewriter, SyntaxTree oldTree, SyntaxTree newTree)
{
if (oldTree != newTree)
{
//update compilation as the syntaxTree changed
compilation = compilation.ReplaceSyntaxTree(oldTree, newTree);
rewriter.Model = compilation.GetSemanticModel(newTree);
}
return compilation;
}
/// <summary>
/// rewrites the SyntaxTree of the class Bar, updates the compilation as well as the semantic model of the passed rewriter
/// </summary>
private static void RewriteBar(Rewriter rewriter, CSharpCompilation compilation, SyntaxTree firstSyntaxTree)
{
var otherRewriter = new Rewriter(true);
var otherTree = compilation.SyntaxTrees.Last();
otherRewriter.Model = compilation.GetSemanticModel(otherTree);
var otherResultTree = otherRewriter.Visit(otherTree.GetRoot()).SyntaxTree;
compilation = UpdateIfNecessary(compilation, otherRewriter, otherTree, otherResultTree);
rewriter.Model = compilation.GetSemanticModel(firstSyntaxTree);
}
public class Rewriter : CSharpSyntaxRewriter
{
public SemanticModel Model { get; set; }
private bool _firstRun = true;
private bool _changeSomething;
public ITypeSymbol ParameterTypeFirstRun { get; set; }
public ITypeSymbol ParameterTypeSecondRun { get; set; }
public Rewriter (bool changeSomething)
{
_changeSomething = changeSomething;
}
public override SyntaxNode VisitClassDeclaration(ClassDeclarationSyntax node)
{
node = (ClassDeclarationSyntax)base.VisitClassDeclaration(node);
//remember the types of the parameter
if (_firstRun)
ParameterTypeFirstRun = GetTypeSymbol (node);
else
ParameterTypeSecondRun = GetTypeSymbol (node);
_firstRun = false;
//change something and return updated node
if(_changeSomething)
node = node.WithMembers(node.Members.Add(GetMethod()));
return node;
}
/// <summary>
/// Gets the type of the first parameter of the first method
/// </summary>
private ITypeSymbol GetTypeSymbol(ClassDeclarationSyntax classDeclaration)
{
var members = classDeclaration.Members;
var methodSymbol = (IMethodSymbol) Model.GetDeclaredSymbol(members[0]);
return methodSymbol.Parameters[0].Type;
}
private MethodDeclarationSyntax GetMethod()
{
return (MethodDeclarationSyntax)
CSharpSyntaxTree.ParseText (@"public void SomeMethod(){ }").GetRoot().ChildNodes().First();
}
}
private static SyntaxTree[] GetTrees()
{
var treeList = new List<SyntaxTree>();
treeList.Add(CSharpSyntaxTree.ParseText(Source.Foo));
treeList.Add(CSharpSyntaxTree.ParseText(Source.Bar));
return treeList.ToArray();
}
private static Compilation GetTestCompilation()
{
var mscorlib = MetadataReference.CreateFromFile(typeof(object).Assembly.Location);
var refs = new List<PortableExecutableReference> { mscorlib };
// I used this to test it with a reference to an external assembly
// var testAssembly = MetadataReference.CreateFromFile(@"../../../Demo.TypeSymbol.TestAssembly/bin/Debug/Demo.TypeSymbol.TestAssembly.dll");
// refs.Add (testAssembly);
return CSharpCompilation.Create("dummyAssembly", GetTrees(), refs);
}
}
public static class Source
{
public static string Foo => @"
// for test with external assembly
//using Demo.TypeSymbol.TestAssembly;
namespace MyAssembly
{
public class Foo
{
public Foo(Foo x)
{
}
}
}
";
public static string Bar => @"
namespace MyAssembly
{
public class Bar
{
public Bar(int i)
{
}
}
}
";
}
}
一种可能性是调用SymbolFinder.FindSimilarSymbols，它将在新解决方案中为您提供一个按名称和其他一些属性匹配的符号。从那里，您可以在新的编译中使用Equals。