fix(parser): support CAST to an array type for MySQL multi-valued indexes (#2506)

MySQL defines a multi-valued index key part by casting to an array, e.g.
CAST(data->'$.zips' AS UNSIGNED ARRAY). The trailing ARRAY keyword was not
reachable, so both the CREATE INDEX and the ALTER TABLE form failed to parse.

ARRAY is accepted as a further word of the cast target type, the way INT
UNSIGNED already is, so no model change is needed and the deparsed statement
round trips. It is added to the CAST production only, where MySQL allows it,
which leaves the ARRAY<type> constructor form untouched.

Closes the last open group of #2490.

Author: minleejae

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -9955,7 +9955,13 @@ CastExpression CastExpression():
             ")"
         )
         |
-        type=ColDataType() { retval.setColDataType(type); }
+        (
+            type=ColDataType() { retval.setColDataType(type); }
+            // MySQL casts to an array of the given type when a multi-valued index key part is
+            // defined, e.g. CAST(data->'$.zips' AS UNSIGNED ARRAY). ARRAY reads as a further
+            // word of the type, the way INT UNSIGNED already does.
+            [ <K_ARRAY_LITERAL> { type.setDataType(type.getDataType() + " ARRAY"); } ]
+        )
     )
 
     // BigQuery FORMAT clause

src/test/java/net/sf/jsqlparser/expression/CastExpressionTest.java

@@ -13,6 +13,7 @@
 
 import net.sf.jsqlparser.JSQLParserException;
 import net.sf.jsqlparser.expression.operators.relational.ParenthesedExpressionList;
+import net.sf.jsqlparser.parser.CCJSqlParserUtil;
 import net.sf.jsqlparser.statement.select.PlainSelect;
 import net.sf.jsqlparser.test.TestUtils;
 import org.junit.jupiter.api.Assertions;
@@ -155,4 +156,18 @@ void testNestedCompositeTypeCastIssue2341() throws JSQLParserException {
         Assertions.assertEquals(1, parenthesedCast.size());
         Assertions.assertInstanceOf(CastExpression.class, parenthesedCast.get(0));
     }
+
+    @Test
+    public void testCastToArrayIssue2490() throws JSQLParserException {
+        // MySQL casts to an array of the given type when a multi-valued index key part is
+        // defined, and accepts the same cast anywhere else an expression is allowed.
+        assertSqlCanBeParsedAndDeparsed("SELECT CAST(data -> '$.zips' AS UNSIGNED ARRAY) FROM t");
+        assertSqlCanBeParsedAndDeparsed("SELECT CAST(x AS CHAR (10) ARRAY) FROM t");
+
+        PlainSelect select = (PlainSelect) CCJSqlParserUtil
+                .parse("SELECT CAST(data -> '$.zips' AS UNSIGNED ARRAY) FROM t");
+        CastExpression cast = Assertions.assertInstanceOf(CastExpression.class,
+                select.getSelectItem(0).getExpression());
+        Assertions.assertEquals("UNSIGNED ARRAY", cast.getColDataType().getDataType());
+    }
 }

src/test/java/net/sf/jsqlparser/statement/alter/AlterTest.java

@@ -2414,4 +2414,10 @@ public void testAlterTableAddIndexKeyPartWithPrefixLengthAndDirectionIssue2490()
         assertSqlCanBeParsedAndDeparsed("ALTER TABLE t ADD INDEX i33 (c1 (20) ASC)");
         assertSqlCanBeParsedAndDeparsed("ALTER TABLE t ADD UNIQUE INDEX i34 (c1 (10) DESC)");
     }
+
+    @Test
+    public void testAlterTableAddMultiValuedIndexIssue2490() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed(
+                "ALTER TABLE t ADD INDEX i31 ((CAST(data -> '$.zips' AS UNSIGNED ARRAY)))");
+    }
 }

src/test/java/net/sf/jsqlparser/statement/create/CreateIndexTest.java

@@ -234,4 +234,10 @@ public void testCreateFullTextAndSpatialIndexIssue2490() throws JSQLParserExcept
         assertSqlCanBeParsedAndDeparsed("CREATE FULLTEXT INDEX i18 ON t (body) WITH PARSER ngram");
         assertSqlCanBeParsedAndDeparsed("CREATE SPATIAL INDEX i19 ON t (g)");
     }
+
+    @Test
+    public void testCreateMultiValuedIndexIssue2490() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed(
+                "CREATE INDEX i20 ON t ((CAST(data -> '$.zips' AS UNSIGNED ARRAY)))");
+    }
 }