Feature request - native sandbox function call

[AsafFisher]

I feel like making one binary that maps COW to both host and guest would be cool, that way the sandboxed function can be compiled to the same binary and a call to the function can be done in a native way without a string name but rather by:

#[sandboxed]
fn calculate(){}
guest.call(calculate)

How does that sound?

[ludfjig]

Hello, I've also been thinking about something similar., and I think something like this could be awesome and definitely a cool proof of concept.

In addition to your suggestion, it might also be possible for the proc macro above function to write a new source file which can be compiled to a guest, and then also potentially compile the guest as well. Calling the function on the host side then transparently creates a new sandbox and calls into the code-generated guest.

[danbugs]

Perhaps partially addressed by #376
cc: @syntactically