Extracted array ranges should not be shared even if the original was.

Author: aardvark179

src/main/java/org/truffleruby/core/array/ArrayCopyOnWriteNode.java

@@ -35,7 +35,7 @@ protected Object extractFromMutableArray(RubyArray array, int start, int length,
             @CachedLibrary("store") ArrayStoreLibrary stores) {
         int size = array.size;
         Object cowStore = stores.extractRange(store, 0, size);
-        Object range = stores.extractRange(store, start, start + length);
+        Object range = stores.extractRangeAndUnshare(store, start, start + length);
         array.store = cowStore;
         return range;
     }
@@ -44,7 +44,7 @@ protected Object extractFromMutableArray(RubyArray array, int start, int length,
     protected Object extractFromNonMutableArray(RubyArray array, int start, int length,
             @Bind("array.store") Object store,
             @CachedLibrary("store") ArrayStoreLibrary stores) {
-        Object range = stores.extractRange(store, start, start + length);
+        Object range = stores.extractRangeAndUnshare(store, start, start + length);
         return range;
     }
 }

src/main/java/org/truffleruby/core/array/library/ArrayStoreLibrary.java

@@ -143,6 +143,10 @@ public Object extractRange(Object store, int start, int end) {
         return new DelegatedArrayStorage(store, start, (end - start));
     }
 
+    public Object extractRangeAndUnshare(Object store, int start, int end) {
+        return extractRange(store, start, end);
+    }
+
     /** Copy a range from this array store into a plane Object[]. */
     public abstract Object[] boxedCopyOfRange(Object store, int start, int length);
 

src/main/java/org/truffleruby/core/array/library/SharedArrayStorage.java

@@ -153,6 +153,12 @@ protected Object extractRange(int start, int end,
         return new SharedArrayStorage(stores.extractRange(storage, start, end));
     }
 
+    @ExportMessage
+    protected Object extractRangeAndUnshare(int start, int end,
+            @CachedLibrary(limit = "1") ArrayStoreLibrary stores) {
+        return stores.extractRange(storage, start, end);
+    }
+
     @ExportMessage
     protected Object[] boxedCopyOfRange(int start, int length,
             @CachedLibrary(limit = "1") ArrayStoreLibrary stores) {