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shortenFullyQualifiedTypes corrupts method references on fields (x.field::m -> bogus import x.field)

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@maxandersen y travaille déjà.

Depuis le 6/10/2026.

  • #3134 par @maxandersen — ouverte

Évaluation

Difficulté
3/5
Temps estimé
1-2 jours
Accessibilité débutants
25/100
Type d'issue
Bug
Clarté
Clairement spécifiée
Activité
À l'abandon
Stack technique
java
Domaine
build-system

Piste de recherche

Start by reading the implementation of shortenFullyQualifiedTypes() added in #3005 and the related tests; the issue does not name their file paths. Reproduce with the supplied Java example and run spotlessApply followed by compileJava. Done means catalog.aliases::get remains unchanged, no bogus import is added, and a regression test covers the case. A linked open pull request (#3134) indicates work is already underway.

Rédigé par le modèle d'indexation à partir du texte de l'issue.

Description

Summary

shortenFullyQualifiedTypes() (added in #3005) corrupts a method reference on a field of a local variable. It treats localVar.field::method as if localVar.field were a fully-qualified type, shortens it to field::method, and injects a bogus import localVar.field; — which does not compile.

Because it only manifests on spotlessApply (not the read-only spotlessCheck), a developer runs spotlessApply, commits, and then the project no longer builds.

Version
  • com.diffplug.spotless 8.10.3 (Gradle plugin)
  • JDK 11 / 17 (reproduces on both)
Minimal reproducer

build.gradle:

plugins {
    id 'java'
    id 'com.diffplug.spotless' version '8.10.3'
}
repositories { mavenCentral() }
spotless { java { shortenFullyQualifiedTypes() } }

src/main/java/Example.java:

import java.util.Map;
import java.util.function.Function;

public class Example {
    static class Catalog {
        Map<String, String> aliases;
    }

    String demo(Catalog catalog) {
        return find(catalog.aliases::get);   // method ref on a field of a local var
    }

    String find(Function<String, String> f) {
        return f.apply("x");
    }
}
Steps
./gradlew spotlessApply
./gradlew compileJava
Actual

spotlessApply rewrites the file to:

import java.util.Map;
import java.util.function.Function;
import catalog.aliases;          // <-- bogus import of a non-existent package/type

public class Example {
    ...
    String demo(Catalog catalog) {
        return find(aliases::get);   // <-- qualifier dropped, now unresolved
    }
    ...
}

and compilation fails:

Example.java: error: package catalog does not exist
Expected

catalog.aliases::get is a method reference on a field access of a local variable, not a fully-qualified type reference. It must be left untouched (no shortening, no import added).

Root cause (guess)

The qualifier-resolution doesn't verify that the left-hand side of a qualified name / method-reference scope actually resolves to a type before shortening. Field accesses on locals/params (x.y, x.y::m, x.y.z) are being misclassified as fully-qualified type names. Checking that the qualifier is a type (not a local variable / field expression) before rewriting should fix it.

Found while enabling the step on a real codebase (jbangdev/jbang), where catalog.aliases::get (a Catalog local + Map field) broke the build.

Langage dominant
Java
Étoiles
5.7k
Forks
565
Merge moyen
2 j 4 h
PR mergées (30 j)
58

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  4. Ouvrez une pull request qui référence le numéro de l'issue.

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