matthiasblaesing commented on issue #7397:
URL: https://github.com/apache/netbeans/issues/7397#issuecomment-2133943592
This is reproducible standalone with the supplied file. I took that as base
and distilled it down to:
```java
import java.util.ArrayList;
public class Dummy {
private void main() {
ArrayList<ArrayList<String[]>> result = new ArrayList<>();
result.stream().map((table) -> {
table.stream().map((row) -> {
return null;
}).forEachOrdered((_item) -> System.out.println();
}).forEachOrdered((_item) -> System.out.println("---"))
);
}
}
```
The compiler rightfully complains about this:
```
Dummy.java:10: error: ')' or ',' expected
}).forEachOrdered((_item) -> System.out.println();
^
Dummy.java:11: error: ';' expected
}).forEachOrdered((_item) -> System.out.println("---"))
^
2 errors
```
But NB raises an Exception as already shown.
I used by debugging-fu and found, that the `JCMethodInvocation` instance
that for the lambda is indeed constructed with an argument list and all
arguments are non-null. So I figured, that some later stage must destroy the
tree for the argument and indeed I got a hit in
`com.sun.tools.javac.tree.TreeTranslator.translate(List<T>)`/`com.sun.tools.javac.tree.TreeTranslator.visitApply(JCMethodInvocation)`.
The transformation that is applied there is an anonymous class in
`com.sun.tools.javac.comp.AttrRecover.AttrRecover(Context)`.
This comment:
https://github.com/openjdk/jdk/blob/617edf3f0dea2b73e4b444e085de2ad282826e31/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/AttrRecover.java#L151-L154
makes no sense from my POV as the TreeTranslator expects the translated tree
in `result`. If the translation result must not be null, the caller could be
modified to check for null and only replace the tree if the translation is
non-null (line 59 and following):
https://github.com/openjdk/jdk/blob/617edf3f0dea2b73e4b444e085de2ad282826e31/src/jdk.compiler/share/classes/com/sun/tools/javac/tree/TreeTranslator.java#L54-L63
Or the `AttrRecover` class needs to be adjusted to return set `result` to
the input tree if it shall not be touched.
@lahodaj would you mind having a look at this? I try to reason my way around
this, but maybe this the right analysis and you can whip up the right fix?!
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