Clarify why we emit ATHROW after expressions of type Nothing

Tests for emitting expressions of type Nothing.

1 files changed, 61 insertions, 0 deletions

diff --git a/test/files/run/nothingTypeNoFramesNoDce.scala b/test/files/run/nothingTypeNoFramesNoDce.scala
new file mode 100644
index 0000000000..3d1298303a
--- /dev/null
+++ b/test/files/run/nothingTypeNoFramesNoDce.scala
@@ -0,0 +1,61 @@
+// See comment in BCodeBodyBuilder
+
+// -target:jvm-1.5 -Ybackend:GenBCode -Yopt:l:none
+// target disables stack map frame generation. in this mode, the ClssWriter just emits dead code as is.
+
+class C {
+  // can't just emit a call to ???, that returns value of type Nothing$ (not Int).
+  def f1: Int = ???
+
+  def f2: Int = throw new Error("")
+
+  def f3(x: Boolean) = {
+    var y = 0
+    // cannot assign an object of type Nothing$ to Int
+    if (x) y = ???
+    else   y = 1
+    y
+  }
+
+  def f4(x: Boolean) = {
+    var y = 0
+    // tests that whatever is emitted after the throw is valid (what? depends on opts, presence of stack map frames)
+    if (x) y = throw new Error("")
+    else   y = 1
+    y
+  }
+
+  def f5(x: Boolean) = {
+    // stack heights need to be the smae. ??? looks to the jvm like returning a value of
+    // type Nothing$, need to drop or throw it.
+    println(
+      if (x) { ???; 10 }
+      else 20
+    )
+  }
+
+  def f6(x: Boolean) = {
+    println(
+      if (x) { throw new Error(""); 10 }
+      else 20
+    )
+  }
+
+  def f7(x: Boolean) = {
+    println(
+      if (x) throw new Error("")
+      else 20
+    )
+  }
+
+  def f8(x: Boolean) = {
+    println(
+      if (x) throw new Error("")
+      else 20
+    )
+  }
+}
+
+object Test extends App {
+  new C()
+}