C#/Java/C++: Add change note for #3110

[hvitved]

@aschackmull and @jbj : We will need a similar change note for Java and C++; can you either provide me the relevant examples, or create the PRs yourself, thanks?

[aschackmull]

Java version:

class C1 {
    String f1;
    C1(String f1) { this.f1 = f1; }
}
class C2 {
    C1 f2;
    String getF2F1() {
        return this.f2.f1; // Nested field read
    }
    void m() {
        this.f2 = new C1("taint");
        sink(this.getF2F1()); // NEW: "taint" reaches here
    }
}

[calumgrant]

Thanks for adding the change note @hvitved. Great stuff!

[calumgrant]

There is an extra line here.

[calumgrant]

I think the example might read better if C1 and F1 could be replaced by real-world examples like Person and Surname. Just an idea.

[calumgrant]

this. is not really idiomatic in C# and could be removed.

[calumgrant]

affects and

I would also state exactly how it improves it, for example that it will find more data-flow steps and potentially more results.

[jbj]

I'll make a separate PR for the C++ version next week, integrating it with other data-flow improvements. I'll put this issue on our team board as a way to remember it.

[MathiasVP]

I'll make a separate PR for the C++ version next week, integrating it with other data-flow improvements. I'll put this issue on our team board as a way to remember it.

If you haven't already written an example feel free to use this port of the Java one:

struct C {
    int f1;
};

struct C2
{
    C f2;

    int getf2f1() {
        return f2.f1; // Nested field read
    }

    void m() {
        f2.f1 = taint();
        sink(getf2f1()); // NEW: "taint" reaches here
    }
};

[jbj]

Thanks, @MathiasVP, for quickly porting the example. If you haven't done so already, will you also turn it into a qltest to check that it actually works?

@hvitved, please use that example for C++.

[MathiasVP]

Thanks, @MathiasVP, for quickly porting the example. If you haven't done so already, will you also turn it into a qltest to check that it actually works?

I checked that the flow was missing prior to #3110, and that we get it after merging the PR. Here's a PR with the qltest: #3426

[jbj]

I've suggested some C/C++-specific tweaks to the change note.

[jbj]

Thanks, Tom! Ping @calumgrant, who has a negative review active.

[calumgrant]

Thanks for the changes @hvitved.