为什么使用动态参数调用通用本地函数会产生 BadImageFormatException？

Question

尝试使用 C# 7 的本地函数，我得到了一些有趣的行为。考虑以下程序：

public void Main()
{
    Console.WriteLine("Entered Main");
    DoSomething("");
}

private void DoSomething(object obj)
{
    Console.WriteLine("Entered DoSomething");
    Generic((dynamic)obj);
    GenericLocal(obj);
    GenericLocal((dynamic)obj); // This breaks the program

    void GenericLocal<T>(T val) => Console.WriteLine("GenericLocal");
}

private void Generic<T>(T val) => Console.WriteLine("Generic");

这会产生：

Entered Main

... 然后抛出一个 BadImageFormatException: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)。堆栈跟踪：

   at UserQuery.DoSomething(Object obj)
   at UserQuery.Main()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

（我在 LINQPad 中运行这个，但我从 dotnetfiddle 得到类似的结果。）

删除代码中指示的行会产生您期望的输出：

Entered Main
Entered DoSomething
Generic
GenericLocal

谁能解释为什么？

Answer 1

当您稍微帮助编译器时，代码不会中断：

GenericLocal<dynamic>((dynamic)obj); // This doesn't break the program

Answer 2

这 turned out to be a bug, but when the dotnet team looked into it they realized they can't easily fix things so local generic methods would work the way that non-local generic methods would. So instead they opted 使编译器在您尝试这样做时产生错误。

CS8322 Cannot pass argument with dynamic type to generic local function 'GenericLocal' with inferred type arguments.

为什么使用动态参数调用通用本地函数会产生 BadImageFormatException？

Why does calling a generic local function with a dynamic parameter produce a BadImageFormatException?

c#

generics

dynamic

c#-7.0