How to wrap a native exception in C++/CLI

Question

Too much late-night programming... I feel like I'm missing something obvious again.

I have a managed function calling an unmanaged function in C++/CLI. The unmanaged function throws a std::exception. The managed function attempts to catch said exception. Unfortunately, the try/catch block fails to catch the unmanaged exception and insists on throwing an SEHException instead.

 

.

void MyClass::MyFunc()
{
	try
	{
		_unmanaged->DoExcept();
	} //<-- debugger shows SEHException is thrown here
	catch(const std::exception& e)
	{
		//Doesn't go here
	}
	catch(...)
	{
		//Goes here, but appears to be catching SEHException...
	}
}

Answer 1

First of all check if _unmanaged contains a valid non-null value and the ‘throw std::exception’ statement is reached.

Answer 2

_unmanaged definitely contains a valid reference. I inserted a throw new exception; as the first statement just to be sure :(

 

I can't step into the static library, though. Is this normal or are there settings I need to tweak? 

 

My references look kinda like this:
WPF Application › C++ / CLI Interop › Static Library.

Answer 3

I think you should use ‘throw std::exception()’ without ‘new’, or add ‘catch(const std::exception * exc)’, but sometimes it is difficult to delete such objects.

 

In order to check if the exception is caught, try this fragment in your managed code:

 

try

{

         //_unmanaged->DoExcept();

         throw std::exception();

}

catch(const std::exception & exc)

{

         //. . . .

}

catch(...)

{

         //. . . .

}

 

Answer 4

It's likely that you're using /clr:pure and not /clr. This means that native function calls are done through PInvoke and PInvoke replaces C++ exceptions (and all other native exceptions it doesn't recognize) with SEHException.

Answer 5

That did it. Thanks :)

 

Any idea why I can't step into the native code? Is this even possible? I'm getting some SEHExceptions I can't catch with std::exception blocks and I'd like to know what they are...

Answer 6

In order to step into unmanaged code when debugging a managed application, you have to turn on a debugger setting in your startup project (Debug Unmanaged Code).