palantir / palantir/palantir-java-format

Formatter generates switch expression incompatible with baseline checkstyle

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#782 4 comments 2 reactions 0 assignees View on GitHub

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bug
Dominant language
Java
Stars
907
Forks
101
Avg merge
1d 3h
Merged PRs (30d)
19

Description

What happened?

The formatter will format

    public void initialize(SchedulerBackend newBackend) {
        this.backend = newBackend;
        schedulableBuilder = switch (schedulingMode) {
            case FIFO -> new ReFifoSchedulableBuilder(rootPool);
            case FAIR -> new ReFairSchedulableBuilder(rootPool, sc);
            default -> throw new SafeIllegalArgumentException(
                    "Unsupported scheduler mode", SafeArg.of("schedulingMode", schedulingMode));
        };
        schedulableBuilder.buildPools();
    }

To

    public void initialize(SchedulerBackend newBackend) {
        this.backend = newBackend;
        schedulableBuilder = switch (schedulingMode) {
            case FIFO -> new ReFifoSchedulableBuilder(rootPool);
            case FAIR -> new ReFairSchedulableBuilder(rootPool, sc);
            default -> throw new SafeIllegalArgumentException(
                    "Unsupported scheduler mode", SafeArg.of("schedulingMode", schedulingMode));};
        schedulableBuilder.buildPools();
    }

which violates checkstyle rules.

What did you want to happen?

In that specific case, the formatter should have been a no-op.

Contributor guide

Open the contributing guide

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.

Research direction

Start by reproducing the formatter output with the Java switch-expression example in the issue and compare it with the baseline checkstyle rules. Trace the formatter path that handles this construct; done means formatting is a no-op for the example and the result does not violate checkstyle.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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