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Java 17 Pattern Matching for Switch (JEP-406) compatibility issue #684

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Java 17 Pattern Matching for Switch (JEP-406) compatibility issue#684

Description

@mcwhitak
mcwhitak
opened on Nov 9, 2021

With version 1.12.0 google-java-format does not properly recognize imports utilized only during pattern matched switches.

As an example, for the following hierarchy

package example.model;

public sealed interface SealedInterface {}

public non-sealed interface TypeA {}
public non-sealed interface TypeB {}

and a Java file using this hierarchy with a pattern matched switch

package example;

import example.model.SealedInterface;
import example.model.TypeA;
import example.model.TypeB;

public class Main {
  public void apply(SealedInterface sealedInterface) {
    switch(sealedInterface) {
      case TypeA a -> System.out.println("A!");
      case TypeB b -> System.out.println("B!");
    }
  }
}

google-java-format will flag import example.model.TypeA and import example.model.TypeB as unused and candidates for removal.

I've recreated this bug in a small repo that illustrates the issue.

Activity

  1. lorenzleutgeb commented on Nov 19, 2021

    @lorenzleutgeb
    lorenzleutgeb
    on Nov 19, 2021

    This appears to be a duplicate of #683 (which turns out to not only apply when throwing exceptions).

  2. copybara-service
    added 4 commits that reference this issue on Nov 19, 2021

    Fix handling of case patterns in unused import removal

    bc719b4

    Fix handling of case patterns in unused import removal

    58978e6

    Update handling of pattern matching in switch

    0bc418e

    Update handling of pattern matching in switch

    8eb478a

  3. cushon commented on Nov 19, 2021

    @cushon
    cushon
    on Nov 19, 2021
    Collaborator

    This is fixed now: the formatter didn't support pattern matching in switches on Java 17 at all, and there was a separate issue specifically about unused imports. Thanks for the report!

  4. cushon
    closed this as completedon Nov 19, 2021
  5. copybara-service
    added 2 commits that reference this issue on Nov 19, 2021

    Update handling of pattern matching in switch

    7c7ad1d

    Update handling of pattern matching in switch

    8be9250
  6. fawind
    added 4 commits that reference this issue on Jan 7, 2022

    Fix handling of case patterns in unused import removal

    1e12319

    Update handling of pattern matching in switch

    80b5cff

    Fix handling of case patterns in unused import removal

    898e775

    Update handling of pattern matching in switch

    9df9127
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