SI-10069 Fix code gen errors with array updates, Nothing

Crashes in ASM or VerifyErrors used to occur when assigning
an expression of type Nothing to an element of a primitive array.

This commit adapts the RHS of the assignment to the element
type to correct this. `adapt` contains logic to insert an
`ATHROW` of the slot of type `Nothing$`, which makes everything
line up. The subsequent array stores become dead code and are
dropped later on in code gen, so the test case compiles to:

  public void foo0(double[]);
    Code:
       0: bipush        42
       2: istore_2
       3: aload_1
       4: iconst_0
       5: aload_0
       6: invokevirtual #30                 // Method throwExpected:()Lscala/runtime/Nothing$;
       9: athrow

I found a similar bug in the emission of primitive unboxing and
fixed that too.

2 files changed, 47 insertions, 0 deletions

diff --git a/test/files/run/t10069.scala b/test/files/run/t10069.scala
new file mode 100644
index 0000000000..4e70b7e814
--- /dev/null
+++ b/test/files/run/t10069.scala
@@ -0,0 +1,34 @@
+object Expected extends Exception
+object Test {
+  def throwExpected: Nothing = throw Expected
+  def foo0(a: Array[Double]) = {  // does compile for Int instead of Double
+    val v = 42
+    a(0) = throwExpected // was crash in code gen: java.lang.NegativeArraySizeException
+  }
+
+  def foo1(a: Array[Double]) = {  // does compile for Int instead of Double
+    a(0) = throwExpected // was VerifyError at runtime
+  }
+
+  def foo2(a: Array[Int]) = {  // does compile for Int instead of Double
+    a(0) = throwExpected // was VerifyError at runtime
+  }
+
+  def foo3(a: Array[String]) = {  // does compile for Int instead of Double
+    a(0) = throwExpected // was already working
+  }
+
+
+  def main(args: Array[String]): Unit = {
+    check(foo0(new Array[Double](1)))
+    check(foo1(new Array[Double](1)))
+    check(foo2(new Array[Int](1)))
+    check(foo3(new Array[String](1)))
+  }
+  def check(f: => Any) {
+    try {f ; sys.error("no exception thrown") 
+    } catch {
+      case Expected =>
+    } 
+  }
+}
diff --git a/test/files/run/t10069b.scala b/test/files/run/t10069b.scala
new file mode 100644
index 0000000000..c9d652bb0c
--- /dev/null
+++ b/test/files/run/t10069b.scala
@@ -0,0 +1,13 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    try {
+      Int.box(???) // crashed the compiler: java.util.NoSuchElementException: key not found: Lscala/runtime/Nothing$;
+      sys.error("no exception")
+    } catch { 
+      case _: NotImplementedError =>
+        // oka
+      case e: Throwable => 
+        sys.error("wrong exception: " + e)
+    }
+  }
+}