在 IL 中对空引用调用实例方法

在 IL 中可以对空引用调用实例方法是否正确？ 有没有例子可以证明这一点..？

是的，这是可能的，只要该方法不使用this因为 CLR 不会对以下内容进行空检查call指示。

You would have to modify the IL by hand as the C# compiler would almost always generate a callvirt instruction¹.

有关详细信息和示例，请参阅此博客文章：

在空引用上调用实例方法 https://web.archive.org/web/20100724141113/http://www.pvle.be:80/2010/07/instance-methods-called-on-null-references/

Sample

.method private hidebysig static void  Main(string[] args) cil managed
{
    .entrypoint
    // Code size       18 (0x12)
    .maxstack  1
    .locals init ([0] class SomeClass o, [1] string hello)
    IL_0000:  nop
    IL_0001:  ldnull
    IL_0002:  stloc.0
    IL_0003:  ldloc.0
    IL_0004:  call       instance string SomeClass::GetHello()
    IL_0009:  stloc.1
    IL_000a:  ldloc.1
    IL_000b:  call       void [mscorlib]System.Console::WriteLine(string)
    IL_0010:  nop
    IL_0011:  ret
} 

¹In fact the reason that the C# compiler emits callvirt even in cases where a simple call instruction would be sufficient is to prevent calling instance methods on null references. With this behavior of the compiler users will get a NullReferenceException so the weird situation of calling a method on a null pointer is avoided. Eric Gunnerson explained this in a blog post some time ago: Why does C# always use callvirt? https://web.archive.org/web/20160112223951/http://blogs.msdn.com/b/ericgu/archive/2008/07/02/why-does-c-always-use-callvirt.aspx Gishu https://stackoverflow.com/users/1695/gishu also has a nice explanation in a related question https://stackoverflow.com/questions/845657/why-is-the-c-sharp-compiler-emitting-a-callvirt-instruction-for-a-gettype-meth/845721#845721.