marshal.structureToptr崩溃Visual Studio

我正在开发一个自定义调试引擎,当我将结构封送到 IntPtr Visual Studio崩溃(正在调试的不是调试器)。

我的结构只不过是:

public struct DocumentContext : IDebugDocumentContext2, IDebugCodeContext2
{
    private string _fileName;

    //.....Implementation of interfaces
}

我的编组代码如下:

        var documentContext = new DocumentContext(_node.FileName);
        var size = Marshal.SizeOf(documentContext);
        IntPtr ptrDocContext = Marshal.AllocHGlobal(size);
        //This is what is crashing 
        //I don't have a chance to catch anything, it just craps out
        //Event log says faulting dll is nt.dll
        Marshal.StructureToPtr(documentContext, ptrDocContext, true); 

我错过什么了吗?