RFR: fixing bugs in NullChecksWriter

[Maurizio Cimadamore]

On Sun, 11 Jan 2026 00:52:12 GMT, Vicente Romero <vromero at openjdk.org> wrote:

> fixing some bugs in NullChecksWriter, reported by John Rose. In particular there was no null check being generated by javac for code like:
> 
> 
> class Test {
>     void m(String someObject) {
>         String! x = "foo";
>         x = (String)someObject;  // no null check generated here
>     }
> 
>     public static void main(String... args) {
>         new Test().m(null);
>     }
> }

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/NullChecksWriter.java line 1:

> 1: /*

visitReturn has the same issue: it checks whether the return expression has a symbol and only generates a null check if there's one.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1883#discussion_r2681542531