C#: Implement ContentSet

[hvitved]

Storing into properties and reading out of properties takes overriding into account. For example, in

interface I
{
    string Prop { get; set; }
}

class C : I
{
    public string Prop { get; set; }

    public void M()
    {
            this.Prop = "taint";
            Sink(((I)this).Prop);
    }
}

this.Prop = "taint" stores into the property C.Prop, whereas ((I)this).Prop read from I.Prop. Before this PR, ((I)this).Prop would give rise to two read steps: one for I.Prop and one for C.Prop. In general, this meant that property reads would fan out to all possible compatible properties, which is better solved using ContentSets.

[michaelnebel]

Looks very nice!

[michaelnebel]

Shouldn't the corresponding TPropertyContent injector be deleted from TContent if Content has been replaced with ContentSet everywhere (it looks like it will require a re-write of ContentApprox)?

[hvitved]

We still need Content, so that can't be deleted. ContentSet is a type used to represent sets of Contents with just a single entity.

[michaelnebel]

Yes, I get that we need the Content type. I am just trying to understand whether we need an injector for properties both as a part of Content and ContentSet?

[hvitved]

We could in principle have just a single injector for TContentSet, but having two makes it more explicit that properties need special treatment.

[michaelnebel]

Ok - thank you!

[michaelnebel]

Doesn't that follow implicitly from p1.getOverridee*().getUnboundDeclaration() = p2 as property contents are always unbound declarations?

[hvitved]

Yes, you are right.

[michaelnebel]

LGTM!