RFR: 8015831: Add lint check for calling overridable methods from a constructor [v7]

[Archie L. Cobbs]

On Thu, 12 Jan 2023 17:29:22 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> I put it there because of switch expressions and `yeild`... ?
>
> Well, yield can... yield a value - `case` doesn't. So I'm confused. Also because the variable is called `referenceExpressionNode` and `CASE` is not an expression. Can `CASE` leave anything on the stack? YIELD does, but CASE?

It's just an artifact of the way switch expressions are handled:

    @Override
    public void visitSwitchExpression(JCSwitchExpression tree) {
        visitScoped(tree, true, t -> {
            scan(t.selector);
            refs.discardExprs(depth);
            RefSet<ExprRef> combinedRefs = new RefSet<>();
            for (List<JCCase> cases = t.cases; cases.nonEmpty(); cases = cases.tail) {
                scan(cases.head);
                combinedRefs.addAll(refs.removeExprs(depth));
            }
            refs.addAll(combinedRefs);
        });
    }

    @Override
    public void visitCase(JCCase tree) {
        scan(tree.stats);          // no need to scan labels
    }

After scanning a switch expression case, the `yield`'ed value will be on the top of the stack.

Then `visitCase` does NOT remove it, so that it can be picked up and removed by `visitSwitchExpression()`.

But this can be cleaned up a little bit, by having `visitSwitchExpression()` not delegate to `visitCase()` but rather iterate through the case statements itself directly. Then we can remove the `CASE` as you suggest.

Also I realized we need to handle `yield`'ed values like `return` values, i.e., collect and remember them until the entire case is complete.

I'll fix.

-------------

PR: https://git.openjdk.org/jdk/pull/11874