Fix https://github.com/konsoletyper/teavm/issues/33

teavm-classlib/src/main/java/org/teavm/classlib/java/lang/TSystem.java

@@ -35,13 +35,32 @@ public final class TSystem extends TObject {
         if (src == null || dest == null) {
             throw new TNullPointerException(TString.wrap("Either src or dest is null"));
         }
-        if (src.getClass() != dest.getClass()) {
-            throw new TArrayStoreException();
-        }
         if (srcPos < 0 || destPos < 0 || length < 0 || srcPos + length > TArray.getLength(src) ||
                 destPos + length > TArray.getLength(dest)) {
             throw new TIndexOutOfBoundsException();
         }
+        if (src != dest) {
+            Class<?> srcType = src.getClass().getComponentType();
+            Class<?> targetType = dest.getClass().getComponentType();
+            if (srcType == null || targetType == null) {
+                throw new TArrayStoreException();
+            }
+            if (srcType != targetType) {
+                if (!srcType.isPrimitive() && !targetType.isPrimitive()) {
+                    Object[] srcArray = (Object[])(Object)src;
+                    Object[] dstArray = (Object[])(Object)dest;
+                    for (int i = 0; i < length; ++i) {
+                        Object elem = srcArray[srcPos++];
+                        if (!targetType.isInstance(elem)) {
+                            throw new TArrayStoreException();
+                        }
+                        dstArray[destPos++] = elem;
+                    }
+                } else if (!srcType.isPrimitive() || !targetType.isPrimitive()) {
+                    throw new TArrayStoreException();
+                }
+            }
+        }
         doArrayCopy(src, srcPos, dest, destPos, length);
     }
 

teavm-classlib/src/test/java/org/teavm/classlib/java/lang/SystemTest.java

@@ -35,6 +35,57 @@ public class SystemTest {
         assertSame(a, dest[2]);
     }
 
+    @Test
+    public void copiesPrimitiveArray() {
+        int[] src = { 23, 24, 25 };
+        int[] dest = new int[3];
+        System.arraycopy(src, 0, dest, 0, 3);
+        assertEquals(23, dest[0]);
+        assertEquals(24, dest[1]);
+        assertEquals(25, dest[2]);
+    }
+
+    @Test
+    public void copiesToSubclassArray() {
+        String[] src = { "foo", "bar", "baz" };
+        Object[] dest = new Object[3];
+        System.arraycopy(src, 0, dest, 0, 3);
+        assertEquals("foo", dest[0]);
+        assertEquals("bar", dest[1]);
+        assertEquals("baz", dest[2]);
+    }
+
+    @Test
+    public void copiesToSuperclassArrayWhenItemsMatch() {
+        Object[] src = { "foo", "bar", "baz" };
+        String[] dest = new String[3];
+        System.arraycopy(src, 0, dest, 0, 3);
+        assertEquals("foo", dest[0]);
+        assertEquals("bar", dest[1]);
+        assertEquals("baz", dest[2]);
+    }
+
+    @Test
+    public void failsToConverItemsCopyingArray() {
+        Object[] src = { "foo", 23, "baz" };
+        String[] dest = new String[3];
+        try {
+            System.arraycopy(src, 0, dest, 0, 3);
+            fail("Exception expected");
+        } catch (ArrayStoreException e) {
+            assertEquals("foo", dest[0]);
+            assertNull(dest[1]);
+            assertNull(dest[2]);
+        }
+    }
+
+    @Test(expected = ArrayStoreException.class)
+    public void failsToCopyToUnrelatedReferenceArray() {
+        String[] src = { "foo", "bar", "baz" };
+        Integer[] dest = new Integer[3];
+        System.arraycopy(src, 0, dest, 0, 3);
+    }
+
     @Test(expected = IndexOutOfBoundsException.class)
     public void failsToCopyArraysWithInvalidIndexes() {
         System.arraycopy(new Object[0], 0, new Object[0], 0, 1);