Feature proposal: Parametric permissions about ward

[evincarofautumn]

Sounds good to me. IIRC I had this in mind to support the “domain locks” in Mono, where each MonoDomain has its own associated global lock. It’s just a matter of getting around to it…

I like the idea of supporting return to annotate the result value of a function, although it might be kinda fiddly to propagate that info up the call tree.

Have to check if this is allowed, but for annotations pertaining to parameters, I wonder if we could support attributes on the parameters themselves, e.g.:

WARD(grant(may_take_capability_lock(return)))
Capability *get_capability(
  int i,
  Capability *caps[i] WARD(need(may_take_capability_lock))
) {
  return caps[i];
}

[bgamari]

Have to check if this is allowed, but for annotations pertaining to parameters, I wonder if we could support attributes on the parameters themselves, e.g.:

I think I would actually prefer to keep the annotation on the function. Afterall, a permission may in fact have more than one parameter, allowing one to represent relations between multiple terms in the source program (e.g. the Task/Capability example given in the description).