MemoryIndex should not fail integer fields that enable doc values. (#12109)

When a field indexes numeric doc values, `MemoryIndex` does an unchecked cast
to `java.lang.Long`. However, the new `IntField` represents the value as a
`java.lang.Integer` so this cast fails. This commit aligns `MemoryIndex` with
`IndexingChain` by casting to `Number` and calling `Number#longValue` instead
of casting to `Long`.

lucene/memory/src/java/org/apache/lucene/index/memory/MemoryIndex.java

@@ -596,7 +596,7 @@ public class MemoryIndex {
                   + fieldName
                   + "]");
         }
-        info.numericProducer.dvLongValues = new long[] {(long) docValuesValue};
+        info.numericProducer.dvLongValues = new long[] {((Number) docValuesValue).longValue()};
         info.numericProducer.count++;
         break;
       case SORTED_NUMERIC:
@@ -605,7 +605,8 @@ public class MemoryIndex {
         }
         info.numericProducer.dvLongValues =
             ArrayUtil.grow(info.numericProducer.dvLongValues, info.numericProducer.count + 1);
-        info.numericProducer.dvLongValues[info.numericProducer.count++] = (long) docValuesValue;
+        info.numericProducer.dvLongValues[info.numericProducer.count++] =
+            ((Number) docValuesValue).longValue();
         break;
       case BINARY:
       case SORTED:

lucene/memory/src/test/org/apache/lucene/index/memory/TestMemoryIndex.java

@@ -39,6 +39,7 @@ import org.apache.lucene.document.DoublePoint;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.document.FieldType;
 import org.apache.lucene.document.FloatPoint;
+import org.apache.lucene.document.IntField;
 import org.apache.lucene.document.IntPoint;
 import org.apache.lucene.document.LongPoint;
 import org.apache.lucene.document.NumericDocValuesField;
@@ -793,4 +794,50 @@ public class TestMemoryIndex extends LuceneTestCase {
     }
     return false;
   }
+
+  public void testIntegerNumericDocValue() throws IOException {
+    // MemoryIndex used to fail when doc values are enabled and numericValue() returns an Integer
+    // such as with IntField.
+    FieldType ft = new FieldType();
+    ft.setDocValuesType(DocValuesType.NUMERIC);
+    ft.freeze();
+    Field field =
+        new Field("field", ft) {
+          {
+            fieldsData = 35;
+          }
+        };
+
+    FieldType multiFt = new FieldType();
+    multiFt.setDocValuesType(DocValuesType.SORTED_NUMERIC);
+    multiFt.freeze();
+    Field multiField =
+        new Field("multi_field", multiFt) {
+          {
+            fieldsData = 42;
+          }
+        };
+
+    Field intField = new IntField("int_field", 50);
+
+    MemoryIndex index = MemoryIndex.fromDocument(Arrays.asList(field, multiField, intField), null);
+    IndexSearcher searcher = index.createSearcher();
+
+    NumericDocValues ndv =
+        searcher.getIndexReader().leaves().get(0).reader().getNumericDocValues("field");
+    assertTrue(ndv.advanceExact(0));
+    assertEquals(35, ndv.longValue());
+
+    SortedNumericDocValues sndv =
+        searcher.getIndexReader().leaves().get(0).reader().getSortedNumericDocValues("multi_field");
+    assertTrue(sndv.advanceExact(0));
+    assertEquals(1, sndv.docValueCount());
+    assertEquals(42, sndv.nextValue());
+
+    sndv =
+        searcher.getIndexReader().leaves().get(0).reader().getSortedNumericDocValues("int_field");
+    assertTrue(sndv.advanceExact(0));
+    assertEquals(1, sndv.docValueCount());
+    assertEquals(50, sndv.nextValue());
+  }
 }