RFR: 8295020: javac emits incorrect code for for-each on an intersection type. [v2]

[Srikanth Adayapalam]

On Fri, 14 Oct 2022 10:16:23 GMT, Srikanth Adayapalam <sadayapalam at openjdk.org> wrote:

>> src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java line 3521:
>> 
>>> 3519:             if (iterableType.getTypeArguments().nonEmpty())
>>> 3520:                 iteratorTarget = types.erasure(iterableType.getTypeArguments().head);
>>> 3521:             tree.expr.type = types.erasure(types.skipTypeVars(tree.expr.type, false));
>> 
>> Shouldn't types already be erased by now (Lower runs after TransTypes?)
>
> Perhaps (actually very likely). This transformation is just simplifying existing code.

> Shouldn't types already be erased by now (Lower runs after TransTypes?)

Consider this case:

<T extends A & B<String>>
    void f(T t) {
        for (String s : t) System.out.println(s);
    }

and the line of code in Lower that reads:

tree.expr.type = types.erasure(types.skipTypeVars(tree.expr.type, false));

types.skipTypeVars(tree.expr.type, false) evaluates to:


java.lang.Object&A&B<java.lang.String>

and so the erasure call is required.

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

PR: https://git.openjdk.org/jdk/pull/10710