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String wrapping is not idempotent

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#935 3 comments 1 reaction 0 assignees View on GitHub

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
java
Domain
tooling

Research direction

Reproduce the issue with the provided TestFormat.java example using the google-java-format 1.15.0 or 1.16.0 all-deps JAR on Java 17. Run formatting repeatedly and compare the switch-expression string layout after each pass. Done means formatting the unchanged file produces identical output on every subsequent run.

Written by the indexing model from the issue text.

Description

bug

This happened with the all deps jar from github, for both versions 1.15.0 and 1.16.0.

$ java --version
openjdk 17.0.6 2023-01-17
OpenJDK Runtime Environment (build 17.0.6+10)
OpenJDK 64-Bit Server VM (build 17.0.6+10, mixed mode)

Example code is

package com.example;

public class TestFormat {

  public void main() {
    var value = 1;
    var responseMessage =
        switch (value) {
          case 1 -> "This is a long string;This is a long string;This is a long string;This is a long string;This is a long string;This is a long string;This is a long string;";
          case 2 -> "some short string";
          case 3 -> "some medium string some medium string some medium string some medium string";
        };
  }
}

Now these strings in the switch statement will be different formatted depending on how often I call google java format.
Weirdly enough, the cosium maven plugin (gjf v1.15.0) does not change the strings in this example at all. This would be preferable for me, but mostly I want a consistent format.

## executing preview only
$ java -jar /home/dev/dev/libs/google-java-format-1.15.0-all-deps.jar Testformat.java 
package com.example;

public class TestFormat {

  public void main() {
    var value = 1;
    var responseMessage =
        switch (value) {
          case 1 -> "This is a long string;This is a long string;This is a long string;This is a"
                        + " long string;This is a long string;This is a long string;This is a long"
                        + " string;";
          case 2 -> "some short string";
          case 3 -> "some medium string some medium string some medium string some medium string";
        };
  }
}

## applying changes
$ java -jar /home/dev/dev/libs/google-java-format-1.15.0-all-deps.jar -r Testformat.java 

## executing preview only
$ java -jar /home/dev/dev/libs/google-java-format-1.15.0-all-deps.jar Testformat.java
package com.example;

public class TestFormat {

  public void main() {
    var value = 1;
    var responseMessage =
        switch (value) {
          case 1 -> "This is a long string;This is a long string;This is a long string;This is a"
              + " long string;This is a long string;This is a long string;This is a long"
              + " string;";
          case 2 -> "some short string";
          case 3 -> "some medium string some medium string some medium string some medium string";
        };
  }
}

The expectation would be that once I format a file every future format call would not change anything anymore as long as nothing was changed on the file.

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