From c4b84e9d63212075127ca34e9d7d450c3d016bc4 Mon Sep 17 00:00:00 2001
From: Albert Meltzer <7529386+kitbellew@users.noreply.github.com>
Date: Sat, 28 Sep 2024 09:00:14 -0700
Subject: [PATCH] Router: check if "NL" for `(` is actually not NL

That will require that the regular no-NL split is produced, as well.
---
 .../scala/org/scalafmt/internal/Router.scala   | 18 +++++++++---------
 .../test/resources/newlines/source_keep.stat   | 17 ++++-------------
 2 files changed, 13 insertions(+), 22 deletions(-)

diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
index 06763c9536..ba973954a5 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
@@ -923,13 +923,14 @@ class Router(formatOps: FormatOps) {
           (if (onlyConfigStyle) opensConfigStyleImplicitParamList(ft)
            else hasImplicitParamList(rightOwner))
 
+        val noSplitForNL = !onlyConfigStyle && right.is[T.LeftBrace]
+        val skipNoSplit = !noSplitForNL &&
+          (style.newlines.keepBreak(newlines) || {
+            if (!handleImplicit) onlyConfigStyle
+            else style.newlines.forceBeforeImplicitParamListModifier
+          })
         val noSplitMod =
-          if (
-            style.newlines.keepBreak(newlines) || {
-              if (!handleImplicit) onlyConfigStyle
-              else style.newlines.forceBeforeImplicitParamListModifier
-            }
-          ) null
+          if (skipNoSplit) null
           else getNoSplitAfterOpening(ft, commentNL = null, spaceOk = !isBracket)
 
         val rightIsComment = right.is[T.Comment]
@@ -1086,10 +1087,9 @@ class Router(formatOps: FormatOps) {
               if (multipleArgs) Split(Newline, cost, policy = oneArgOneLine)
                 .withIndent(extraOneArgPerLineIndent)
               else {
-                val noSplit = !onlyConfigStyle && right.is[T.LeftBrace]
-                val noConfigStyle = noSplit || newlinePolicy.isEmpty ||
+                val noConfigStyle = noSplitForNL || newlinePolicy.isEmpty ||
                   !configStyleFlag
-                Split(NoSplit.orNL(noSplit), cost, policy = newlinePolicy)
+                Split(NoSplit.orNL(noSplitForNL), cost, policy = newlinePolicy)
                   .andPolicy(Policy ? noConfigStyle && singleLine(4)).andPolicy(
                     Policy ? singleArgument && asInfixApp(args.head)
                       .map(InfixSplits(_, ft).nlPolicy),
diff --git a/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat b/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat
index f849f2c014..eaabfbff81 100644
--- a/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat
+++ b/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat
@@ -9463,22 +9463,13 @@ object a {
 rdd.map(
     {case (id, count) => (count, id)})
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
- rdd.map({ case (id, count) =>
--  (count, id)
--})
-+    (count, id)
-+  }
-+)
+rdd.map({ case (id, count) =>
+  (count, id)
+})
 <<< #4133 partial function within apply, long
 maxColumn = 80
 ===
 rdd.map(
     {case (id, count) => (count, id)})
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
--rdd.map({ case (id, count) => (count, id) })
-+rdd.map({ case (id, count) => (count, id) }
-+)
+rdd.map({ case (id, count) => (count, id) })