Add bytecode test to verify absence of Tuple2.apply calls

Author: noti0na1

compiler/test/dotty/tools/backend/jvm/DottyBytecodeTest.scala

@@ -133,6 +133,15 @@ trait DottyBytecodeTest {
     }, l.stringLines)
   }
 
+  def assertNoInvoke(m: MethodNode, receiver: String, method: String): Unit =
+    assertNoInvoke(instructionsFromMethod(m), receiver, method)
+  def assertNoInvoke(l: List[Instruction], receiver: String, method: String): Unit = {
+    assert(!l.exists {
+      case Invoke(_, `receiver`, `method`, _, _) => true
+      case _ => false
+    }, s"Found unexpected invoke of $receiver.$method in:\n${l.stringLines}")
+  }
+
   def diffInstructions(isa: List[Instruction], isb: List[Instruction]): String = {
     val len = Math.max(isa.length, isb.length)
     val sb = new StringBuilder

compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala

@@ -1606,6 +1606,21 @@ class DottyBytecodeTests extends DottyBytecodeTest {
     }
   }
 
+  @Test
+  def simpleTupleExtraction(): Unit = {
+    val code =
+      """class C {
+        |  def f1(t: (Int, String)) =
+        |    val (i, s) = t
+        |    i + s.length
+        |}
+      """.stripMargin
+    checkBCode(code) { dir =>
+      val c = loadClassNode(dir.lookupName("C.class", directory = false).input)
+      assertNoInvoke(getMethod(c, "f1"), "scala/Tuple2$", "apply") // no Tuple2.apply call
+    }
+  }
+
   @Test
   def deprecation(): Unit = {
     val code =