C#编组结构指针有什么区别？

Question

好的,这是有效的:

[StructLayout(LayoutKind.Explicit, Size = 28)]
public unsafe struct HandleProxy
{
    [FieldOffset(0), MarshalAs(UnmanagedType.I4)]
    public JSValueType _ValueType; // JSValueType is an enum

    [FieldOffset(4), MarshalAs(UnmanagedType.I4)]
    public Int32 _ManagedObjectID; 

    [FieldOffset(8)]
    public void* _NativeEngineProxy;

    [FieldOffset(16), MarshalAs(UnmanagedType.I4)]
    public Int32 _EngineID;

    [FieldOffset(20)]
    public void* _Handle;
}

[DllImport("Proxy")]
public static extern void DisposeHandleProxy(HandleProxy* handle);

......这不......

[StructLayout(LayoutKind.Explicit, Size = 20)]
public unsafe struct ValueProxy
{
    [FieldOffset(0), MarshalAs(UnmanagedType.I4)]
    public JSValueType _ValueType; // 32-bit type value.

    [FieldOffset(4), MarshalAs(UnmanagedType.Bool)]
    public bool _Boolean;

    [FieldOffset(4), MarshalAs(UnmanagedType.I4)]
    public Int32 _Integer;

    [FieldOffset(4)]
    public double _Number;

    [FieldOffset(12)]
    public void* _String;
}

[DllImport("Proxy")]
public static extern void DisposeValueProxy(ValueProxy* valueProxy);

那么,有什么区别？我错过了什么.调用"DisposeValueProxy()"会出现以下错误:

"无法封送'参数#1':指针不能引用封送结构.请改用ByRef."

(是的,我可以简单地使用IntPtr/void*代替"ValueProxy*"但这不是我的观点).

对"DisposeHandleProxy()"的调用工作正常.

让我们看看是否有人可以解决这个问题.;)

Answer 1

结构必须是blittable才能创建指向它的指针.第二个结构不是blittable,bool字段是麻烦制造者.根据意图,你必须改为使用byte或int.

这里提供了.NET中blittable的类型概述.

异常消息的建议是非常合理的,将参数声明ref ValueProxy为将其留给pinvoke marshaller以创建具有所需布局的结构的副本.