[lworld] RFR: 8367323: [lworld] javac is rejecting valid code after fix for JDK-8359370

[Maurizio Cimadamore]

On Thu, 11 Sep 2025 02:14:37 GMT, Vicente Romero <vromero at openjdk.org> wrote:

> Recent fix for [JDK-8359370](https://bugs.openjdk.org/browse/JDK-8359370) introduced a minor bug. This code should be accepted by javac:
> 
> class SuperClass<T> {
>     public SuperClass(Object o) {}
> }
> 
> class Sub<T> extends SuperClass<T> {
>     public Sub() {
>         super(new Object() {
>             void foo() {
>                 getClass();
>             }
>         });
>     }
> }
> 
> 
> but it is currently rejected as the `getClass` invocation is considered to be an invocation of an instance method of class `Sub`

Looks good!

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java line 1477:

> 1475:                  * the compiler
> 1476:                  */
> 1477:                 return sym.kind != MTH || !insideClassDef;

I think the "right" thing to do here seems to have to do with membership and whether the access is unqualified or not.

E.g. 
* if we are in the prologue of `A`, and we see a call to `m()`, and `m()` is a member of `A`, then we should fail
* if we are in a class `B` inside the prologue of `A`, and we see a call to `m()`, and `m()` is a member of `B`, then it should be ok
* if we are in a class `B` inside the prologue of `A`, and we see a call to `m()`, and `m()` is a member of _both_ `B` and `A`, then it should be ok
* if we are in a class `B` inside the prologue of `A`, and we see a call to `m()`, and `m()` is a member of `A` then it should fail

The problem seems to be that, by the time we hit the `isEarlyReference` method, we no longer know the "current class" -- so we always check membership against the "outer" class whose prologue we're inspecting.

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java line 1478:

> 1476:                     return TreeInfo.isExplicitThisReference(types, (ClassType)env.enclClass.type, fa.selected);
> 1477:                 }
> 1478:                 if (currentClassSym != env.enclClass.sym) {

stylistic (and optional). In a way, if we added that as part of an `else if` it would make it clear that we're in an "implicit" qualifier case (e.g. simple name). Also, maybe adding a one line comment about why we're doing the extra check might be helpful for future reference.

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

Marked as reviewed by mcimadamore (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/1567#pullrequestreview-3216409900
PR Review Comment: https://git.openjdk.org/valhalla/pull/1567#discussion_r2339555659
PR Review Comment: https://git.openjdk.org/valhalla/pull/1567#discussion_r2344073174