SI-9066 fix null.asInstanceOf[Unit]

3 files changed, 27 insertions, 23 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index 7bfe5a4740..5e903946c1 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -1141,6 +1141,10 @@ abstract class Erasure extends AddInterfaces
         else {
           val tree1 = preErase(tree)
           tree1 match {
+            case TypeApply(fun, targs @ List(targ)) if fun.symbol == Any_asInstanceOf && targ.tpe == UnitTpe =>
+              // SI-9066 prevent transforming `o.asInstanceOf[Unit]` to `o.asInstanceOf[BoxedUnit]`.
+              // adaptMember will then replace the call by a reference to BoxedUnit.UNIT.
+              treeCopy.TypeApply(tree1, transform(fun), targs).clearType()
             case EmptyTree | TypeTree() =>
               tree1 setType specialScalaErasure(tree1.tpe)
             case ArrayValue(elemtpt, trees) =>
diff --git a/test/junit/scala/BoxUnboxTest.scala b/test/junit/scala/BoxUnboxTest.scala
index eb7a35e98c..88b3037e69 100644
--- a/test/junit/scala/BoxUnboxTest.scala
+++ b/test/junit/scala/BoxUnboxTest.scala
@@ -106,14 +106,14 @@ class BoxUnboxTest {
     Unit.unbox({eff(); null}); chk()
     assertThrows[ClassCastException](Unit.unbox({eff(); ""})); chk()
 
-    val n1 = null.asInstanceOf[Unit]              // SI-9066: should be UNIT, but currently null
-    assertThrows[AssertionError](assert(n1 == b)) // should not throw
+    val n1 = null.asInstanceOf[Unit]
+    assert(n1 == b)
 
-    val n2 = null.asInstanceOf[Unit] == b    // SI-9066: should be true, but currently false
-    assertThrows[AssertionError](assert(n2)) // should not throw
+    val n2 = null.asInstanceOf[Unit] == b
+    assert(n2)
 
     def f(a: Any) = "" + a
-    val n3 = f(null.asInstanceOf[Unit])                  // "null", should be "()". probably same cause as SI-602.
-    assertThrows[AssertionError](assertEquals(n3, "()")) // should not throw
+    val n3 = f(null.asInstanceOf[Unit])
+    assertEquals(n3, "()")
   }
 }
diff --git a/test/junit/scala/issues/RunTest.scala b/test/junit/scala/issues/RunTest.scala
index b81a3e1d6f..3ebdc8a72f 100644
--- a/test/junit/scala/issues/RunTest.scala
+++ b/test/junit/scala/issues/RunTest.scala
@@ -186,10 +186,10 @@ class RunTest extends ClearAfterClass {
         |npe(f1(  n3.asInstanceOf[VCI])) + // SI-8097
         |    f1(               n4[VCI])  + // "null"
         |"-"                             +
-        |    f1(null.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f1(  n1.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f1(  n2.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f1(  n3.asInstanceOf[Unit]) + // "null", SI-9066
+        |    f1(null.asInstanceOf[Unit]) +
+        |    f1(  n1.asInstanceOf[Unit]) +
+        |    f1(  n2.asInstanceOf[Unit]) +
+        |    f1(  n3.asInstanceOf[Unit]) +
         |    f1(               n4[Unit]) + // "null"
         |"-"                             +
         |    f2(null.asInstanceOf[Int])  +
@@ -204,10 +204,10 @@ class RunTest extends ClearAfterClass {
         |npe(f2(  n3.asInstanceOf[VCI])) + // SI-8097
         |    f2(               n4[VCI])  + // "null"
         |"-"                             +
-        |    f2(null.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f2(  n1.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f2(  n2.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f2(  n3.asInstanceOf[Unit]) + // "null", SI-9066
+        |    f2(null.asInstanceOf[Unit]) +
+        |    f2(  n1.asInstanceOf[Unit]) +
+        |    f2(  n2.asInstanceOf[Unit]) +
+        |    f2(  n3.asInstanceOf[Unit]) +
         |    f2(               n4[Unit]) + // "null"
         |"-"                             +
         |    f3(null.asInstanceOf[Int])  +
@@ -222,10 +222,10 @@ class RunTest extends ClearAfterClass {
         |npe(f3(  n3.asInstanceOf[VCI])) + // SI-8097
         |    f3(               n4[VCI])  + // "null"
         |"-"                             +
-        |    f3(null.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f3(  n1.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f3(  n2.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f3(  n3.asInstanceOf[Unit]) + // "null", SI-9066
+        |    f3(null.asInstanceOf[Unit]) +
+        |    f3(  n1.asInstanceOf[Unit]) +
+        |    f3(  n2.asInstanceOf[Unit]) +
+        |    f3(  n3.asInstanceOf[Unit]) +
         |    f3(               n4[Unit]) + // "null"
         |"-"                             +
         |    f4(null.asInstanceOf[Int])  +
@@ -240,14 +240,14 @@ class RunTest extends ClearAfterClass {
         |npe(f5(  n3.asInstanceOf[VCI])) + // SI-8097
         |npe(f5(               n4[VCI])) + // SI-8097
         |"-"                             +
-        |    f6(null.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f6(  n1.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f6(  n2.asInstanceOf[Unit]) + // "null", SI-9066
-        |    f6(  n3.asInstanceOf[Unit]) + // "null", SI-9066
+        |    f6(null.asInstanceOf[Unit]) +
+        |    f6(  n1.asInstanceOf[Unit]) +
+        |    f6(  n2.asInstanceOf[Unit]) +
+        |    f6(  n3.asInstanceOf[Unit]) +
         |    f6(               n4[Unit])   // "null"
       """.stripMargin
 
     assertEquals(run[String](code),
-      "0000null-0npe0npenull-nullnullnullnullnull-0000null-0npe0npenull-nullnullnullnullnull-0000null-0npe0npenull-nullnullnullnullnull-00000-0npe0npenpe-nullnullnullnullnull")
+      "0000null-0npe0npenull-()()()()null-0000null-0npe0npenull-()()()()null-0000null-0npe0npenull-()()()()null-00000-0npe0npenpe-()()()()null")
   }
 }