[bugfix] Fix issue with attribute not accepting some reserved keywords as valid name

Closes #2381

Author: gabriele-tomassetti

exist-core/src/main/antlr/org/exist/xquery/parser/XQuery.g

@@ -2224,6 +2224,12 @@ reservedKeywords returns [String name]
 	"map" { name = "map"; }
 	|
 	"array" { name = "array"; }
+	|
+	"copy-namespaces" { name = "copy-namespaces"; }
+	|
+    "empty-sequence" { name = "empty-sequence"; }
+    |
+    "schema-element" { name = "schema-element"; }
 	;
 
 /**

exist-core/src/test/java/org/exist/xquery/ReservedNamesConflictTest.java

@@ -0,0 +1,83 @@
+/*
+ * eXist-db Open Source Native XML Database
+ * Copyright (C) 2001 The eXist-db Authors
+ *
+ * [email protected]
+ * http://www.exist-db.org
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+package org.exist.xquery;
+
+import antlr.RecognitionException;
+import antlr.TokenStreamException;
+import org.exist.xquery.parser.XQueryAST;
+import org.exist.xquery.parser.XQueryLexer;
+import org.exist.xquery.parser.XQueryParser;
+import org.exist.xquery.parser.XQueryTokenTypes;
+import org.exist.xquery.parser.XQueryTreeParser;
+import org.junit.jupiter.api.Test;
+
+import java.io.StringReader;
+
+import static org.junit.Assert.*;
+
+/**
+ * @author <a href="[email protected]">Adam Retter</a>
+ * @author <a href="[email protected]">Gabriele Tomassetti</a>
+ */
+public class ReservedNamesConflictTest {
+
+    @Test
+    public void reservedNamesIssueTest() throws RecognitionException, XPathException, TokenStreamException {
+        final String query = "xquery version \"3.1\";\n" +
+                "<foo copy-namespaces=\"bar\"/>,\n" +
+                "<foo empty-sequence=\"bar\"/>,\n" +
+                "<foo schema-element=\"bar\"/>";
+
+        // parse the query into the internal syntax tree
+        final XQueryContext context = new XQueryContext();
+        final XQueryLexer lexer = new XQueryLexer(context, new StringReader(query));
+        final XQueryParser xparser = new XQueryParser(lexer);
+        xparser.xpath();
+        if (xparser.foundErrors()) {
+            fail(xparser.getErrorMessage());
+            return;
+        }
+
+        final XQueryAST ast = (XQueryAST) xparser.getAST();
+
+        final XQueryTreeParser treeParser = new XQueryTreeParser(context);
+        final PathExpr expr = new PathExpr(context);
+        treeParser.xpath(ast, expr);
+        if (treeParser.foundErrors()) {
+            fail(treeParser.getErrorMessage());
+            return;
+        }
+
+
+        final XQueryAST one = (XQueryAST) ast.getNextSibling().getFirstChild().getFirstChild();
+        final XQueryAST two = (XQueryAST) ast.getNextSibling().getFirstChild().getNextSibling().getFirstChild();
+        final XQueryAST three = (XQueryAST) ast.getNextSibling().getFirstChild().getNextSibling().getNextSibling().getFirstChild();
+
+        assertEquals("copy-namespaces", one.getText());
+        assertEquals("empty-sequence", two.getText());
+        assertEquals("schema-element", three.getText());
+        assertEquals(XQueryTokenTypes.ATTRIBUTE, one.getType());
+        assertEquals(XQueryTokenTypes.ATTRIBUTE, two.getType());
+        assertEquals(XQueryTokenTypes.ATTRIBUTE, three.getType());
+    }
+}
+