Merge pull request #2717 from retronym/ticket/6574

SI-6574 Support @tailrec for extension methods.

5 files changed, 44 insertions, 0 deletions

diff --git a/test/files/neg/t6574.check b/test/files/neg/t6574.check
new file mode 100644
index 0000000000..c67b4ed804
--- /dev/null
+++ b/test/files/neg/t6574.check
@@ -0,0 +1,7 @@
+t6574.scala:4: error: could not optimize @tailrec annotated method notTailPos$extension: it contains a recursive call not in tail position
+    println("tail")
+    ^
+t6574.scala:8: error: could not optimize @tailrec annotated method differentTypeArgs$extension: it is called recursively with different type arguments
+    {(); new Bad[String, Unit](0)}.differentTypeArgs
+                                   ^
+two errors found
diff --git a/test/files/neg/t6574.scala b/test/files/neg/t6574.scala
new file mode 100644
index 0000000000..bba97ad62e
--- /dev/null
+++ b/test/files/neg/t6574.scala
@@ -0,0 +1,10 @@
+class Bad[X, Y](val v: Int) extends AnyVal {
+  @annotation.tailrec final def notTailPos[Z](a: Int)(b: String) {
+    this.notTailPos[Z](a)(b)
+    println("tail")
+  }
+
+  @annotation.tailrec final def differentTypeArgs {
+    {(); new Bad[String, Unit](0)}.differentTypeArgs
+  }
+}
diff --git a/test/files/pos/t6574.scala b/test/files/pos/t6574.scala
new file mode 100644
index 0000000000..59c1701eb4
--- /dev/null
+++ b/test/files/pos/t6574.scala
@@ -0,0 +1,19 @@
+class Bad[X, Y](val v: Int) extends AnyVal {
+  def vv = v
+  @annotation.tailrec final def foo[Z](a: Int)(b: String) {
+    this.foo[Z](a)(b)
+  }
+
+  @annotation.tailrec final def differentReceiver {
+    {(); new Bad[X, Y](0)}.differentReceiver
+  }
+
+  @annotation.tailrec final def dependent[Z](a: Int)(b: String): b.type = {
+    this.dependent[Z](a)(b)
+  }
+}
+
+class HK[M[_]](val v: Int) extends AnyVal {
+  def hk[N[_]]: Unit = if (false) hk[M] else ()
+}
+
diff --git a/test/files/run/t6574b.check b/test/files/run/t6574b.check
new file mode 100644
index 0000000000..e10fa4f810
--- /dev/null
+++ b/test/files/run/t6574b.check
@@ -0,0 +1 @@
+List(5, 4, 3, 2, 1)
diff --git a/test/files/run/t6574b.scala b/test/files/run/t6574b.scala
new file mode 100644
index 0000000000..df329a31ca
--- /dev/null
+++ b/test/files/run/t6574b.scala
@@ -0,0 +1,7 @@
+object Test extends App {
+  implicit class AnyOps(val i: Int) extends AnyVal {
+    private def parentsOf(x: Int): List[Int] = if (x == 0) Nil else x :: parentsOf(x - 1)
+    def parents: List[Int] = parentsOf(i)
+  }
+  println((5).parents)
+}