Scalafmt is not idempotent

[github-julien-pie]

Hey there 👋

First of all, thanks for your work, scalafmt is great tool ❤️

I've just discovered a case where scalafmt is not idempotent:

• Version: 3.4.0
• Integration: CLI
• Configuration:

version = 3.4.0

runner.dialect = scala213
preset = defaultWithAlign
maxColumn = 100
importSelectors = singleLine
assumeStandardLibraryStripMargin = true
rewrite.rules = [RedundantBraces, RedundantParens]
rewrite.redundantBraces.stringInterpolation = true
project.git = true
optIn.breaksInsideChains = true
lineEndings = preserve
trailingCommas = preserve
newlines.implicitParamListModifierPrefer = before

Steps

Given code like this:

class Test {
  val test = foo.bar.baz
    .map(thisvariablenameisreallylong =>
      fr"""UPDATE mytable
          |SET
          | column = $thisvariablenameisreallylong
          |WHERE column2 = ${foo.bar}""".stripMargin.update.run
    ).getOrElse {
      ().pure[ConnectionIO]
    }
}

When I run scalafmt like this:

scalafmt --debug ./Test.scala

Problem

Scalafmt formats code like this:

class Test {
  val test = foo.bar.baz
    .map(thisvariablenameisreallylong => fr"""UPDATE mytable
                                             |SET
                                             | column = $thisvariablenameisreallylong
                                             |WHERE column2 = ${foo.bar}""".stripMargin.update.run).getOrElse {
      ().pure[ConnectionIO]
    }
}

But when I run scalafmt once again:

scalafmt --debug ./Test.scala

Scalafmt formats code like this:

class Test {
  val test = foo.bar.baz
    .map(thisvariablenameisreallylong =>
      fr"""UPDATE mytable
          |SET
          | column = $thisvariablenameisreallylong
          |WHERE column2 = ${foo.bar}""".stripMargin.update.run
    ).getOrElse {
      ().pure[ConnectionIO]
    }
}

Expectation

Scalafmt should be idempotent. Meaning it could be applied multiple times without changing the result beyond the initial application.

Workaround

I can deactivate the scalafmt using https://scalameta.org/scalafmt/docs/configuration.html#-format-off

Note

I just noticed this issue #339. Maybe there's a fix for my particular case?