From 268a36b549694a1b518a00fefb5513b5cc1c96dd Mon Sep 17 00:00:00 2001
From: dawe <dawedawe@posteo.de>
Date: Thu, 6 Jun 2024 16:00:11 +0200
Subject: [PATCH] - guard against a newline induced precedence change to fix
 2866 - add test - add changelog entry

---
 CHANGELOG.md                                  |  4 ++--
 .../PatternMatchingTests.fs                   | 23 +++++++++++++++++++
 src/Fantomas.Core/CodePrinter.fs              |  2 +-
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8a5d3fa57..b47d80445b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,9 @@
 # Changelog
 
-## [Unreleased]
+## 6.3.8 - 2024-06-06
 
 ### Fixed
-* Fix loss of tuple type annotation without parens. [#2942](https://github.com/fsprojects/fantomas/issues/2942)
+* Fix precedence change of `||>` due to inserted newline. [#2866](https://github.com/fsprojects/fantomas/issues/2866)
 
 ## 6.3.7 - 2024-06-01
 
diff --git a/src/Fantomas.Core.Tests/PatternMatchingTests.fs b/src/Fantomas.Core.Tests/PatternMatchingTests.fs
index 74db05a604..6b4bb86383 100644
--- a/src/Fantomas.Core.Tests/PatternMatchingTests.fs
+++ b/src/Fantomas.Core.Tests/PatternMatchingTests.fs
@@ -2286,3 +2286,26 @@ match synExpr with
     ) -> Some ident.idRange
 | _ -> defaultTraverse synExpr
 """
+
+[<Test>]
+let ``insertion of a newline changes precedence of the ||> operator, 2866`` () =
+    formatSourceString
+        """
+let value =
+    match "string" with
+    | "value" -> "1", "2"
+    | _ -> "111111111111111111111111111111111111111111111111111111111111111111111", "22222222222222222222222222222222222"
+    ||> createTuple
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let value =
+    (match "string" with
+     | "value" -> "1", "2"
+     | _ ->
+         "111111111111111111111111111111111111111111111111111111111111111111111", "22222222222222222222222222222222222")
+    ||> createTuple
+"""
diff --git a/src/Fantomas.Core/CodePrinter.fs b/src/Fantomas.Core/CodePrinter.fs
index de5cba95e8..5a13896a61 100644
--- a/src/Fantomas.Core/CodePrinter.fs
+++ b/src/Fantomas.Core/CodePrinter.fs
@@ -2163,7 +2163,7 @@ let genMultilineInfixExpr (node: ExprInfixAppNode) =
         match node.LeftHandSide with
         | IsIfThenElse _ when (ctx.Config.IndentSize - 1 <= node.Operator.Text.Length) ->
             autoParenthesisIfExpressionExceedsPageWidth (genExpr node.LeftHandSide) ctx
-        | Expr.Match _ when (ctx.Config.IndentSize <= node.Operator.Text.Length) ->
+        | Expr.Match _ when (ctx.Config.IndentSize - 1 <= node.Operator.Text.Length) ->
             let ctxAfterMatch = genExpr node.LeftHandSide ctx
 
             let lastClauseIsSingleLine =