Hacktoberfest 2026: the issues maintainers tagged for October, open and beginner-friendly. Browse Hacktoberfest issues

JDK types first reached by a source scan stay uninspected when any package is preloaded: `isFunctionalInterface()` is false for `PrivilegedAction`

Open
#119 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
48/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
java
Domain
backend

Research direction

Start by tracing ClassSymbolScanner.loadType(..., LAZILY) and the JavaInspectorImpl copy and commit loops described in the issue, then compare the preload and no-preload paths in the reproduction. Check how CompiledTypesManagerImpl.preload and on-demand inspection affect the type's inspection state. Done means the reproduced PrivilegedAction reports run() as its single abstract method and isFunctionalInterface() returns true after parsing with any preload.

Written by the indexing model from the issue text.

Description

Reproduction
SourceSet javaBase = SourceSetImpl.javaBase();
SourceSet sources = new SourceSetImpl.Builder().setName(JavaInspector.TEST_PROTOCOL)
        .setUri(URI.create("file:/")).setDependencies(List.of(javaBase)).build();
InputConfiguration config = new InputConfigurationImpl.Builder().addSourceSets(sources)
        .addClassPath("jmod:java.base").build();
JavaInspector ji = new io.codelaser.maddi.inspection.openjdk.JavaInspectorImpl();
ji.preload("java.base::java.util.");          // any preload; see the table below
ji.initialize(config);
TypeInfo x = ji.parse(Map.of("a.X", """
        package a;
        import java.security.PrivilegedAction;
        class X {
            static String m() {
                PrivilegedAction<String> action = () -> "x";
                return action.run();
            }
        }
        """), new JavaInspector.ParseOptions.Builder().build())
        .parseResult().primaryTypes().stream().findFirst().orElseThrow();
// visit m()'s body, take the Lambda, and inspect l.abstractFunctionalTypeInfo()
preloads PrivilegedAction after parse
none hasBeenInspected()=true, singleAbstractMethod()=run(), isFunctionalInterface()=true
java.base::java.util. hasBeenInspected()=false, singleAbstractMethod()=null, isFunctionalInterface()=false
java.base::java.util. + java.base::java.security hasBeenInspected()=true, run(), true

Seen on 0.9.5-alpha.11.

Expected

After parse returns, every type the parse result refers to answers member queries correctly, whatever was preloaded. Failing that, it should answer by completing the type on demand. A TypeInfo that silently reports "no single abstract method" while the parser has just resolved a lambda against it is the worst case: callers can't tell an uninspected type from a non-functional one.

Where it seems to come from

This is from reading the code; I haven't stepped through it.

  • ClassSymbolScanner.loadType(..., LAZILY) skips the members and setSingleAbstractMethod, and doesn't commit.
  • The type is completed later, by JavaInspectorImpl's "copy into CTM" loop. That loop commits scanned.primaryTypes(), classSymbolScanner().typesLoaded() (= infoByFqn.typesLoadedForThisSourceSet()), and the preloads.
  • With a preload, a shared-JDK task exists (preloadPass / wireSharedJdk). A platform type first reached during the source scan is then loaded on that shared task and registered for the JDK source set. It is not registered for the scanned set, so the loop never sees it. The preload pass's own commit loop has already run by then.
  • Without any preload there is no shared task, so the scanner's own typesLoaded() includes the type and it gets committed.
  • Also, CompiledTypesManagerImpl.preload is a TODO, and LAZILY-loaded types from the openjdk scanner don't register setOnDemandInspection. So TypeInfoImpl.inspection.get() returns the uncommitted builder instead of completing the type.
Impact

Code that branches on isFunctionalInterface() or singleAbstractMethod() for a lambda's or method reference's target type gets the wrong answer whenever that JDK interface wasn't covered by a preload. The same probably holds for any other member query on such a type (methods(), fields(), ...).

Dominant language
Java
Stars
1
Forks
1
Avg merge
2h 51m
Merged PRs (30d)
3

Getting set up

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from CodeLaser/maddi

All issues in CodeLaser/maddi

Similar issues

More Java issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.