From c134faf9791a1783cc5af0906ca5619ce82e2973 Mon Sep 17 00:00:00 2001
From: Albert Meltzer <7529386+kitbellew@users.noreply.github.com>
Date: Wed, 2 Oct 2024 10:42:04 -0700
Subject: [PATCH] RedundantBraces: keep if a comment is attached

Also, check comments only for scala2.
---
 .../org/scalafmt/rewrite/RedundantBraces.scala     | 14 +++++++++++---
 .../test/resources/rewrite/RedundantBraces-if.stat | 14 ++++++++------
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala
index 12946b11b3..5a6585a176 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala
@@ -300,11 +300,19 @@ class RedundantBraces(implicit val ftoks: FormatTokens)
       session: Session,
       style: ScalafmtConfig,
   ): (Replacement, Replacement) = {
+    @tailrec
+    def okComment(xft: FormatToken): Boolean =
+      ftoks.prevNotTrailingComment(xft) match {
+        case Right(x) =>
+          if ((x eq xft) && x.hasBreak)
+            !ftoks.isAttachedCommentThenBreak(ftoks.next(ft))
+          else !session.isRemovedOnLeft(x, true) || okComment(ftoks.prev(x))
+        case _ => false
+      }
     val ok = ft.meta.rightOwner match {
-      case _: Term.Block => ftoks.prevNotTrailingComment(ft).isRight &&
-        !braceSeparatesTwoXmlTokens &&
+      case _: Term.Block => !braceSeparatesTwoXmlTokens &&
         (style.dialect.allowSignificantIndentation ||
-          !elseAfterRightBraceThenpOnLeft)
+          okComment(ft) && !elseAfterRightBraceThenpOnLeft)
       case _ => true
     }
     if (ok) (left, removeToken) else null
diff --git a/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat b/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat
index 9ec4c789de..bf96ec37ce 100644
--- a/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat
+++ b/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat
@@ -424,9 +424,11 @@ object a {
   }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       searchIndices()
--  // else swallow the termination and wait for pull
-+    // else swallow the termination and wait for pull
- }
+object a {
+  override def onUpstreamFinish(): Unit =
+    if (buffer.isEmpty)
+      completeStage()
+    else if (isAvailable(out)) {
+      searchIndices()
+    } // else swallow the termination and wait for pull
+}