semanticdb-javac terminates in error "silently", due to a NullPointerException #686
Description
Platform: VSCode/Metals/Bloop on Windows 10 with Java 8 GraalVM 20
This issue is a propagation of scalameta/metals#6191
It looks like it went sour in:
Still broken against v0.9.9 against which I did my debugging below.
It seems to be triggered by an annotation on a local variable
private <T> Function<InvocationHandler, T> getConstructor(Class<T> contract) {
@SuppressWarnings("unchecked")
Constructor<T> constructor = (Constructor<T>) Which throws a NullPointerException here
JavacTrees.getElement(TreePath) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\api\JavacTrees.java:319)
JavacTrees.getElement(TreePath) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\api\JavacTrees.java:119)
SemanticdbTrees.annotationBuilder(AnnotationTree) (Unknown Source:87)
SemanticdbTrees.annotations(Tree) (Unknown Source:71)
SemanticdbVisitor.emitSymbolInformation(Element,Tree) (Unknown Source:134)
SemanticdbVisitor.emitSymbolOccurrence(Element,Tree,Name,Semanticdb$SymbolOccurrence$Role,CompilerRange) (Unknown Source:114)
SemanticdbVisitor.resolveVariableTree(VariableTree,TreePath) (Unknown Source:282)
SemanticdbVisitor.resolveNodes() (Unknown Source:209)
SemanticdbVisitor.buildTextDocument(CompilationUnitTree) (Unknown Source:94)
SemanticdbTaskListener.onFinishedAnalyze(TaskEvent) (Unknown Source:96)
SemanticdbTaskListener.finished(TaskEvent) (Unknown Source:63)
ClientCodeWrapper$WrappedTaskListener.finished(TaskEvent) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\api\ClientCodeWrapper.java:681)
MultiTaskListener.finished(TaskEvent) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\api\MultiTaskListener.java:111)
JavaCompiler.flow(Env,Queue) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\main\JavaCompiler.java:1342)
JavaCompiler.flow(Env) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\main\JavaCompiler.java:1296)
JavaCompiler.compile2() (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\main\JavaCompiler.java:901)
JavaCompiler.compile(List,List,Iterable) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\main\JavaCompiler.java:860)
Main.compile(String[],String[],Context,List,Iterable) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\main\Main.java:523)
Main.compile(String[],Context,List,Iterable) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\main\Main.java:381)
Main.compile(String[],Context) (c:\Program Files\Java\graalvm-ce-java8-20.3.3\src\com\sun\tools\javac\main\Main.java:370)
JavacTrees
public Symbol getElement(TreePath path) {
JCTree tree = (JCTree) path.getLeaf();
Because here
variableTreePath ends up being null.
For some reason the new construct cannot cope with annotations on local variables. If I move the annotation to the method level it seems to get past the null pointer problem.
Why it fails on that exact instance is unclear, I have different java codebases where I use it on locals, fields or classes where I didn't see the issue surface.
Perhaps it has to do with the method being private (e.g. the variable was named local14 in the tree model).
More I wasn't able to determine whilst debugging on the release version of the Javac plugin.
I think I collected al relevant info. So far I still have the break on the code line just before the NullPointerException occurs should I need to attempt to gather anything else.