Re: [DotGNU]Bug - null objects and stack traces.

[Rhys Weatherley]

Gopal V wrote:

> "call" instruction does not throw a NullReferenceException , but
> "callvirt" does ... But "why ?" is not something I can answer.

"call" doesn't look at the "this" value on the stack, so it
never knows if it is null or not.

"callvirt" must look at the "this" value on the stack, to fetch
the pointer to the vtable from the object.  In the process,
it must check for the null pointer.

See "pnet/engine/cvm_call.c" under COP_CALL and COP_CALL_VIRTUAL
for the gory details.

Cheers,

Rhys.