improvement: Make sure 'isAccessibleFrom' always succeeds

[tgodzik]

Previously, everything would break is isAccessibleFrom threw an exception. Now, we default to false, which is the safer option.

Connected to #5268

[ckipp01]

Looks good, however this does raise a question for me. Should something like this just exist in the compiler? For me looking at isAccessibleFrom it gives no indication that it can throw. I think in the past I remember someone saying that all the asserts needed to stay as is since they really do indicate bugs, but we've hit on this so much that it makes me wonder if some more "safer" methods like this should just live in the compiler for tools to use.

[tgodzik]

I think the compiler should never throw an assertion error, since those are really not useful at all. And they do happen quite often from what I see.

Maybe we should raise an issue upstream?

[ckipp01]

I think the compiler should never throw an assertion error, since those are really not useful at all. And they do happen quite often from what I see.

Maybe we should raise an issue upstream?

Yea, let me collect a few different PRs where we'e done this sort of thing just to show what we mean, and then I'll create an issue for it in Dotty.

[tgodzik]

Thanks!