Guard against overflow in fjbg. Closes #3671, no review.

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@23033 5e8d7ff9-d8ef-0310-90f0-a4852d11357a

src/fjbg/ch/epfl/lamp/fjbg/JExtendedCode.java

@@ -575,12 +575,13 @@ public class JExtendedCode extends JCode {
         }
 
         int keyMin = keys[0], keyMax = keys[keys.length - 1];
-        int keyRange = keyMax - keyMin + 1;
+        /** Calculate in long to guard against overflow. */
+        long keyRange = (long)keyMax - keyMin + 1;
         if ((double)keys.length / (double)keyRange >= minDensity) {
             // Keys are dense enough, use a table in which holes are
             // filled with defaultBranch.
-            int[] newKeys = new int[keyRange];
-            Label[] newBranches = new Label[keyRange];
+            int[] newKeys = new int[(int)keyRange];
+            Label[] newBranches = new Label[(int)keyRange];
             int oldPos = 0;
             for (int i = 0; i < keyRange; ++i) {
                 int key = keyMin + i;

test/files/pos/bug3671.scala

@@ -0,0 +1,7 @@
+object Crash {
+  def crash(value: Int): Unit =
+      value match {
+        case java.lang.Integer.MAX_VALUE => println("MAX_VALUE")
+        case java.lang.Integer.MIN_VALUE => println("MIN_VALUE") 
+       }
+}