[lworld] RFR: 8369062: [lworld] Do not allow references to instance fields before a this() invocation

[Chen Liang]

On Sat, 4 Oct 2025 02:40:02 GMT, Vicente Romero <vromero at openjdk.org> wrote:

> implementation of [1] in valhalla. This means that code like:
> 
> class Inner7 {
>     private int x;
> 
>     public Inner7(byte y) {
>         x = y;  // error can't refer to an instance field before a this() invocation
>         this((int)y);
>     }
>     public Inner7(int x) {
>         this.x = x;
>         super();
>     }
> }
> 
> 
> won't be accepted by javac
> [1] https://bugs.openjdk.org/browse/JDK-8368719

Looks good. Now we are consistently rejecting this field access before this constructor delegation.

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java line 1490:

> 1488:                                 if (mode != PrologueVisitorMode.WARNINGS_ONLY) {
> 1489:                                     if (mode == PrologueVisitorMode.THIS_CONSTRUCTOR) {
> 1490:                                         reportPrologueError(tree, sym);

Can merge this with the `else` in the `allowValueClasses` check above for simplicity.

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

Marked as reviewed by liach (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/1659#pullrequestreview-3301528522
PR Review Comment: https://git.openjdk.org/valhalla/pull/1659#discussion_r2403727779