From 2624a460d8ddd19960bf36b6f47bddcfe62d685c Mon Sep 17 00:00:00 2001
From: Albert Meltzer <7529386+kitbellew@users.noreply.github.com>
Date: Sat, 2 Nov 2024 11:53:16 -0700
Subject: [PATCH] Router: inline braces-to-parens policy

We don't need to use it before the opening brace, only after.
---
 .../org/scalafmt/internal/FormatOps.scala     | 15 +++--------
 .../scala/org/scalafmt/internal/Router.scala  | 26 +++++++++++--------
 2 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
index db679c4e4..338a1fbfe 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/FormatOps.scala
@@ -2977,10 +2977,10 @@ class FormatOps(
   @inline
   def indentedPackage(pkg: Pkg): Boolean = indentedPackage(pkg.body)
 
-  def getBracesToParensModAndPolicy(rb: FormatToken, mod: Modification)(implicit
+  def getBracesToParensMod(rb: FormatToken, mod: Modification)(implicit
       style: ScalafmtConfig,
       ft: FormatToken,
-  ): (Modification, Policy) = {
+  ): Modification = {
     val isWithinBraces = ft.left.is[T.LeftBrace]
     val ok = initStyle.rewrite.bracesToParensForOneLineApply &&
       style.rewrite.trailingCommas.isOptional && (mod eq Space) &&
@@ -2990,16 +2990,7 @@ class FormatOps(
       // check if all of them can be converted to parens
       insideBracesBlock(if (isWithinBraces) ft else next(ft), rb.left).ranges
         .forall(x => couldHaveBracesConvertedToParens(x.lt.leftOwner))
-    if (ok) {
-      val end = Policy.End < rb.left
-      val beforeClose = prev(rb)
-      val policy = Policy ? isWithinBraces &&
-        end ==> Policy.on(rb.left, "BracesToParens") {
-          case Decision(`beforeClose`, ss) => ss
-              .flatMap(s => if (s.isNL) None else Some(s.withMod(NoSplit)))
-        }
-      SpaceOrNoSplit(end) -> policy
-    } else (mod, Policy.noPolicy)
+    if (ok) SpaceOrNoSplit(Policy.End < rb.left) else mod
   }
 
 }
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 79d0b02a7..3ab64833f 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
@@ -390,9 +390,9 @@ class Router(formatOps: FormatOps) {
         }
 
         val noSplitMod = xmlSpace(leftOwner)
-        val (slbMod, slbParensPolicy) =
-          if (singleLineDecisionOpt.isEmpty) (noSplitMod, NoPolicy)
-          else getBracesToParensModAndPolicy(closeFT, noSplitMod)
+        val slbMod =
+          if (singleLineDecisionOpt.isEmpty) noSplitMod
+          else getBracesToParensMod(closeFT, noSplitMod)
         val singleLineSplitOpt = singleLineDecisionOpt.map { sld =>
           val sldPolicy = getSingleLinePolicy
           val expire = leftOwner.parent match {
@@ -403,6 +403,13 @@ class Router(formatOps: FormatOps) {
             case _ => endOfSingleLineBlock(closeFT)
           }
           // copy logic from `( ...`, binpack=never, defining `slbSplit`
+          val slbParensPolicy = Policy ? (slbMod eq noSplitMod) || {
+            val beforeClose = prev(closeFT)
+            Policy.End < close ==> Policy.on(close, "BracesToParens") {
+              case Decision(`beforeClose`, ss) => ss
+                  .flatMap(s => if (s.isNL) None else Some(s.withMod(NoSplit)))
+            }
+          }
           Split(slbMod, 0).withSingleLine(expire, noSyntaxNL = true)
             .andPolicy(sldPolicy & slbParensPolicy)
         }
@@ -425,8 +432,8 @@ class Router(formatOps: FormatOps) {
           else {
             val nlPolicy = newlineBeforeClosingCurly
             val policy = singleLineSplitOpt match {
-              case Some(slbSplit) if slbParensPolicy.isEmpty =>
-                Policy.after(lambdaExpire, "FNARR") {
+              case Some(slbSplit) if slbMod eq noSplitMod =>
+                Policy.after(lambdaExpire, s"FNARR($slbSplit)") {
                   case Decision(FormatToken(`lambdaExpire`, _, _), ss) =>
                     var hadNoSplit = false
                     val nlSplits = ss.flatMap { s =>
@@ -444,7 +451,7 @@ class Router(formatOps: FormatOps) {
 
         val singleLineSplit = singleLineSplitOpt match {
           case Some(slbSplit)
-              if slbParensPolicy.nonEmpty || lambdaSplit.isIgnored => slbSplit
+              if (slbMod ne noSplitMod) || lambdaSplit.isIgnored => slbSplit
           case _ => Split.ignored
         }
         val splits = Seq(singleLineSplit, lambdaSplit, nlSplit)
@@ -1514,11 +1521,8 @@ class Router(formatOps: FormatOps) {
                   .exists(x => isTokenLastOrAfter(x.left, roPos))
             }
           } =>
-        val rb = matching(lb)
-        val (mod, toParensPolicy) = getBracesToParensModAndPolicy(rb, Space)
-        val policy = Policy
-          .RelayOnSplit { case (s, _) => s.isNL }(toParensPolicy, NoPolicy)
-        Seq(Split(mod, 0, policy = policy))
+        val mod = getBracesToParensMod(matching(lb), Space)
+        Seq(Split(mod, 0))
 
       // Delim
       case FormatToken(left, _: T.Comma, _)