Router: slightly penalize interpolation newlines

scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala

@@ -107,13 +107,18 @@ class FormatOps(
           ) start
           else null
         }
-      case _: T.LeftBrace
-          if start.left.is[T.RightParen] &&
-            start.leftOwner.is[Member.SyntaxValuesClause] &&
-            start.rightOwner.parent.exists {
-              case p: Tree.WithBody => p.body eq start.rightOwner
-              case _ => false
-            } => null
+      case _: T.LeftBrace => start.left match {
+          case _: T.RightParen
+              if start.leftOwner.is[Member.SyntaxValuesClause] &&
+                start.rightOwner.parent.exists {
+                  case p: Tree.WithBody => p.body eq start.rightOwner
+                  case _ => false
+                } => null
+          case _: T.Interpolation.SpliceStart
+              if style.newlines.inInterpolation eq
+                Newlines.InInterpolation.allow => null
+          case _ => start
+        }
       case _: T.RightBracket if start.left.is[T.RightBracket] => null
       case _: T.LeftBracket => null
       case _: T.Dot => start.rightOwner match {

scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala

@@ -87,12 +87,18 @@ class Router(formatOps: FormatOps) {
                   else s.copy(optimalAt = None)
                 }
             }
-          else Policy ?
-            (style.newlines.sourceIgnored || isTripleQuote(m.left.text)) ||
+          else if (!style.newlines.sourceIgnored && !isTripleQuote(m.left.text))
             Policy.on(end, "INTERP-KEEP-NONL") {
               case Decision(x, ss) if x.noBreak =>
                 ss.map(s => if (s.isNL) s.withPenalty(penalty) else s)
             }
+          else Policy ?
+            (style.newlines.inInterpolation eq
+              Newlines.InInterpolation.allow) &&
+            Policy.on(end, "INTERP-ALLOW-NL", rank = -1) {
+              case Decision(_, ss) => ss
+                  .map(s => if (s.isNL) s.withPenalty(1) else s)
+            }
         }
         val split = Split(NoSplit, 0, policy = policy)
         val alignIndents =

scalafmt-tests-community/intellij/src/test/scala/org/scalafmt/community/intellij/CommunityIntellijScalaSuite.scala

@@ -13,7 +13,7 @@ abstract class CommunityIntellijScalaSuite(name: String)
 class CommunityIntellijScala_2024_2_Suite
     extends CommunityIntellijScalaSuite("intellij-scala-2024.2") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(48186930)
+  override protected def totalStatesVisited: Option[Int] = Some(48190466)
 
   override protected def builds = Seq(getBuild(
     "2024.2.28",
@@ -51,7 +51,7 @@ class CommunityIntellijScala_2024_2_Suite
 class CommunityIntellijScala_2024_3_Suite
     extends CommunityIntellijScalaSuite("intellij-scala-2024.3") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(48366702)
+  override protected def totalStatesVisited: Option[Int] = Some(48370242)
 
   override protected def builds = Seq(getBuild(
     "2024.3.4",

scalafmt-tests-community/scala2/src/test/scala/org/scalafmt/community/scala2/CommunityScala2Suite.scala

@@ -9,7 +9,7 @@ abstract class CommunityScala2Suite(name: String)
 
 class CommunityScala2_12Suite extends CommunityScala2Suite("scala-2.12") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(35850116)
+  override protected def totalStatesVisited: Option[Int] = Some(35856475)
 
   override protected def builds =
     Seq(getBuild("v2.12.20", dialects.Scala212, 1277))
@@ -18,7 +18,7 @@ class CommunityScala2_12Suite extends CommunityScala2Suite("scala-2.12") {
 
 class CommunityScala2_13Suite extends CommunityScala2Suite("scala-2.13") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(44610131)
+  override protected def totalStatesVisited: Option[Int] = Some(44618135)
 
   override protected def builds =
     Seq(getBuild("v2.13.14", dialects.Scala213, 1287))

scalafmt-tests-community/scala3/src/test/scala/org/scalafmt/community/scala3/CommunityScala3Suite.scala

@@ -9,15 +9,15 @@ abstract class CommunityScala3Suite(name: String)
 
 class CommunityScala3_2Suite extends CommunityScala3Suite("scala-3.2") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(33372940)
+  override protected def totalStatesVisited: Option[Int] = Some(33385186)
 
   override protected def builds = Seq(getBuild("3.2.2", dialects.Scala32, 791))
 
 }
 
 class CommunityScala3_3Suite extends CommunityScala3Suite("scala-3.3") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(36020956)
+  override protected def totalStatesVisited: Option[Int] = Some(36033019)
 
   override protected def builds = Seq(getBuild("3.3.3", dialects.Scala33, 861))
 

scalafmt-tests-community/spark/src/test/scala/org/scalafmt/community/spark/CommunitySparkSuite.scala

@@ -9,7 +9,7 @@ abstract class CommunitySparkSuite(name: String)
 
 class CommunitySpark3_4Suite extends CommunitySparkSuite("spark-3.4") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(72459436)
+  override protected def totalStatesVisited: Option[Int] = Some(72480315)
 
   override protected def builds =
     Seq(getBuild("v3.4.1", dialects.Scala213, 2585))
@@ -18,7 +18,7 @@ class CommunitySpark3_4Suite extends CommunitySparkSuite("spark-3.4") {
 
 class CommunitySpark3_5Suite extends CommunitySparkSuite("spark-3.5") {
 
-  override protected def totalStatesVisited: Option[Int] = Some(76628137)
+  override protected def totalStatesVisited: Option[Int] = Some(76649844)
 
   override protected def builds =
     Seq(getBuild("v3.5.3", dialects.Scala213, 2756))

scalafmt-tests/shared/src/test/resources/newlines/source_classic.stat

@@ -10503,3 +10503,19 @@ val output = evaluated match {
         |"$s"""".stripMargin
   case x => x.toString
 }
+<<< #4133 breaks in overflowing interpolation, allow
+maxColumn = 76
+===
+object a {
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options.common.debug.print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+}
+>>>
+object a {
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options.common.debug.print(
+    s"Files to be formatted:\n${projectFiles.mkString("\n")}\n"
+  )
+}

scalafmt-tests/shared/src/test/resources/newlines/source_fold.stat

@@ -9811,3 +9811,18 @@ val output = evaluated match {
         |"$s"""".stripMargin
   case x => x.toString
 }
+<<< #4133 breaks in overflowing interpolation, allow
+maxColumn = 76
+===
+object a {
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options.common.debug.print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+}
+>>>
+object a {
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+}

scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat

@@ -10252,3 +10252,19 @@ val output = evaluated match {
         |"$s"""".stripMargin
   case x => x.toString
 }
+<<< #4133 breaks in overflowing interpolation, allow
+maxColumn = 76
+===
+object a {
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options.common.debug.print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+}
+>>>
+object a {
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options.common.debug.print(
+    s"Files to be formatted:\n${projectFiles.mkString("\n")}\n"
+  )
+}

scalafmt-tests/shared/src/test/resources/newlines/source_unfold.stat

@@ -10629,3 +10629,22 @@ val output =
     case x =>
       x.toString
   }
+<<< #4133 breaks in overflowing interpolation, allow
+maxColumn = 76
+===
+object a {
+  options.common.debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options.common.debug.print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+}
+>>>
+object a {
+  options
+    .common
+    .debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+  options
+    .common
+    .debug
+    .print(s"Files to be formatted:\n${projectFiles.mkString("\n")}\n")
+}

scalafmt-tests/shared/src/test/scala/org/scalafmt/FormatTests.scala

@@ -138,7 +138,7 @@ class FormatTests extends FunSuite with CanRunTests with FormatAssertions {
     val explored = Debug.explored.get()
     logger.debug(s"Total explored: $explored")
     if (!onlyUnit && !onlyManual)
-      assertEquals(explored, 1495532, "total explored")
+      assertEquals(explored, 1496399, "total explored")
     val results = debugResults.result()
     // TODO(olafur) don't block printing out test results.
     // I don't want to deal with scalaz's Tasks :'(