palantir / palantir/palantir-java-format

Non-deterministic indentation when 2nd, 4th, etc arguments of methods are long

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Dominant language
Java
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Description

What happened?

Both of the following indentation levels are allowed, and depending on what the state of the code was before running the formatter, it is non-deterministic which one is output.

    Object object = foo(
            foo,
                    veryVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVeryyyyyyyyyyyyyVeryVeryLongVariableName,
            foo,
                    veryVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVeryyyyyyyyyyyyyVeryVeryLongVariableName);
    Object object = foo(
            foo,
            veryVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVeryyyyyyyyyyyyyVeryVeryLongVariableName,
            foo,
            veryVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVerVeryVeryyyyyyyyyyyyyVeryVeryLongVariableName);

What did you want to happen?

We should be deterministic/consistent about which indentation level is output by the formatter. I think the latter makes the most sense. In our case, we discovered this while using Map.of(), where the former indentation level does make some sense, but I don't think it makes sense to allow that just for Map.of().

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 two long-argument examples from the issue, including the Map.of() case mentioned. Trace the formatter's method-argument indentation behavior and add coverage for the alternating long-argument layout. Done means repeated formatting produces one consistent indentation style.

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
45/100

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