From a34977551e9e13090e6b5201f7d91879464f991c Mon Sep 17 00:00:00 2001
From: Matt Bovel <matthieu@bovel.net>
Date: Thu, 23 Dec 2021 12:56:18 +0100
Subject: [PATCH] Allow return in tailrec position

---
 .../src/dotty/tools/dotc/transform/TailRec.scala |  2 +-
 tests/run/tailrec-return.check                   |  2 ++
 tests/run/tailrec-return.scala                   | 16 ++++++++++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 tests/run/tailrec-return.check
 create mode 100644 tests/run/tailrec-return.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/TailRec.scala b/compiler/src/dotty/tools/dotc/transform/TailRec.scala
index 9330016f3292..eb239f00bcce 100644
--- a/compiler/src/dotty/tools/dotc/transform/TailRec.scala
+++ b/compiler/src/dotty/tools/dotc/transform/TailRec.scala
@@ -444,7 +444,7 @@ class TailRec extends MiniPhase {
 
         case Return(expr, from) =>
           val fromSym = from.symbol
-          val inTailPosition = fromSym.is(Label) && tailPositionLabeledSyms.contains(fromSym)
+          val inTailPosition = !fromSym.is(Label) || tailPositionLabeledSyms.contains(fromSym)
           cpy.Return(tree)(transform(expr, inTailPosition), from)
 
         case _ =>
diff --git a/tests/run/tailrec-return.check b/tests/run/tailrec-return.check
new file mode 100644
index 000000000000..6b81a566d1a7
--- /dev/null
+++ b/tests/run/tailrec-return.check
@@ -0,0 +1,2 @@
+6
+false
diff --git a/tests/run/tailrec-return.scala b/tests/run/tailrec-return.scala
new file mode 100644
index 000000000000..53b5ae73b82d
--- /dev/null
+++ b/tests/run/tailrec-return.scala
@@ -0,0 +1,16 @@
+object Test:
+
+  @annotation.tailrec
+  def sum(n: Int, acc: Int = 0): Int =
+    if n != 0 then return sum(n - 1, acc + n)
+    acc
+
+  @annotation.tailrec
+  def isEven(n: Int): Boolean =
+    if n != 0 && n != 1 then return isEven(n - 2)
+    if n == 1 then return false
+    true
+
+  def main(args: Array[String]): Unit =
+    println(sum(3))
+    println(isEven(5))