Another test

Author: odersky

tests/pos/Buffer.scala

@@ -0,0 +1,22 @@
+import language.experimental.captureChecking
+
+// Extract of the problem in collection.mutable.Buffers
+trait Buffer[A]:
+
+  def apply(i: Int): A = ???
+
+  def flatMapInPlace(f: A => IterableOnce[A]^): this.type = {
+    val g = f
+    val s = 10
+     // capture checking: we need the copy since we box/unbox on g* on the next line
+      // TODO: This looks fishy, need to investigate
+      // Alternative would be to mark `f` as @unbox. It's not inferred
+      // since `^ appears in a function result, not under a box.
+    val newElems = new Array[(IterableOnce[A]^{f})](s)
+    var i = 0
+    while i < s do
+      val x = g(this(i))
+      newElems(i) = x
+      i += 1
+    this
+  }