Scalafmt Rewrite Is Not Value Preserving

[adamgfraser]

This template is a guideline, not a strict requirement.

• Version: 0.5
• Integration: IntelliJ
• Configuration:

version = "2.4.2"
maxColumn = 120
align = most
continuationIndent.defnSite = 2
assumeStandardLibraryStripMargin = true
docstrings = JavaDoc
lineEndings = preserve
includeCurlyBraceInSelectChains = false
danglingParentheses = true
spaces {
  inImportCurlyBraces = true
}
optIn.annotationNewlines = true

rewrite.rules = [SortImports, RedundantBraces]

Steps

Given code like this:

      childContext.onDone { _ =>
        val _ = self.withChildren(_.remove(childContext))
      }

When I run scalafmt like this:

scalafmt

Problem

Scalafmt formats code like this:

      childContext.onDone(_ => val _ = self.withChildren(_.remove(childContext)))

Expectation

I would like the formatted output to look like this:

      childContext.onDone { _ =>
        val _ = self.withChildren(_.remove(childContext))
      }

[kitbellew]

@adamgfraser could you explain the title of this issue, please? does it mean that the current formatting doesn't result in equivalent scala?

[adamgfraser]

@kitbellew Sure, sorry. The original code is valid code that compiles. The rewritten code does not compile. The assignment syntax is only valid within a block.

[kitbellew]

@adamgfraser ah, thank you. a similar problem (#1718) was fixed in #1715 and released in 2.4.2. when i run your test on 2.4.2, it produces

childContext.onDone { _ => val _ = self.withChildren(_.remove(childContext)) }

are you certain you are experiencing it with 2.4.2 and not an earlier version?

[adamgfraser]

@kitbellew Very certain. We encountered it just after merging a PR to update to 2.4.2.