Only read date unit words as date units when they are function arguments

An unquoted YEAR, MONTH, DAY, HOUR, MINUTE or SECOND was parsed as a
DateUnitExpression anywhere an expression could start, so a column with
one of those names lost its spelling and its qualifier, and broke
UPDATE ... SET (a, year) = ... with a ClassCastException. The word is now
parsed as a Column and converted to a DateUnitExpression only when it is
a whole argument of a function, which keeps its original spelling.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: edeadington

src/main/java/net/sf/jsqlparser/expression/DateUnitExpression.java

@@ -18,12 +18,16 @@ public class DateUnitExpression extends ASTNodeAccessImpl implements Expression
 
     private final DateUnit type;
 
+    private final String text;
+
     public DateUnitExpression(DateUnit type) {
         this.type = Objects.requireNonNull(type);
+        this.text = type.toString();
     }
 
     public DateUnitExpression(String DateUnitStr) {
         this.type = Objects.requireNonNull(DateUnit.from(DateUnitStr));
+        this.text = DateUnitStr;
     }
 
     public DateUnit getType() {
@@ -38,7 +42,7 @@ public <T, S> T accept(ExpressionVisitor<T> expressionVisitor, S context) {
 
     @Override
     public String toString() {
-        return type.toString();
+        return text;
     }
 
     public enum DateUnit {

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

@@ -1039,6 +1039,47 @@ public class CCJSqlParser extends AbstractJSqlParser<CCJSqlParser> {
         function.setExtraKeyword(getNextToken().image);
     }
 
+    /**
+     * An unquoted YEAR, MONTH, DAY, HOUR, MINUTE or SECOND passed on its own as a function argument, as in
+     * DATEADD(day, 1, d), is a date unit. Anywhere else it is an ordinary identifier, so it is parsed as a
+     * Column and only converted here, once it is known to be a whole argument.
+     */
+    private void normalizeDateUnitArguments(Function function) {
+        ExpressionList<?> parameters = function.getParameters();
+        if (parameters == null || parameters instanceof ParenthesedExpressionList) {
+            return;
+        }
+        ExpressionList<Expression> normalized = null;
+        for (int i = 0; i < parameters.size(); i++) {
+            if (!isDateUnitColumn(parameters.get(i))) {
+                continue;
+            }
+            Column column = (Column) parameters.get(i);
+            DateUnitExpression unit = new DateUnitExpression(column.getColumnName());
+            linkAST(unit, column.getASTNode());
+            if (normalized == null) {
+                normalized = new ExpressionList<Expression>(parameters);
+                normalized.setASTNode(parameters.getASTNode());
+            }
+            normalized.set(i, unit);
+        }
+        if (normalized != null) {
+            function.setParameters(normalized);
+        }
+    }
+
+    private static boolean isDateUnitColumn(Expression expression) {
+        if (!(expression instanceof Column)) {
+            return false;
+        }
+        Node node = ((Column) expression).getASTNode();
+        if (node == null) {
+            return false;
+        }
+        Token first = node.jjtGetFirstToken();
+        return first != null && first == node.jjtGetLastToken() && first.kind == K_DATE_LITERAL;
+    }
+
     private void normalizeOdbcTimestampInterval(Function function) {
         if (!function.isEscaped() || function.getMultipartName().size() != 1
                 || !("TIMESTAMPADD".equalsIgnoreCase(function.getName())
@@ -12074,8 +12115,6 @@ Expression PrimaryExpression() #PrimaryExpression:
         | LOOKAHEAD({ !interrupted && isFunctionAhead() })
                   retval = Function() [ LOOKAHEAD(2) retval = AnalyticExpression( (Function) retval ) ]
 
-        | LOOKAHEAD(2) retval = DateUnitExpression()
-
         | LOOKAHEAD(2, {!interrupted}) retval = IntervalExpression() { dateExpressionAllowed = false; }
 
         | token=<S_DOUBLE>  { retval = new DoubleValue(token.image); }
@@ -12394,13 +12433,6 @@ DateTimeLiteralExpression DateTimeLiteralExpression() : {
     }
 }
 
-DateUnitExpression DateUnitExpression() : {
-    Token t;
-}
-{
-    t=<K_DATE_LITERAL>  { return new DateUnitExpression( t.image ); }
-}
-
 RangeExpression RangeExpression(Expression startExpression):
 {
     Expression endExpression;
@@ -14052,6 +14084,7 @@ Function Function() #Function:
         | function = InternalFunction(false)
     )
     {
+        normalizeDateUnitArguments(function);
         linkAST(function,jjtThis);
         return function;
     }

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

@@ -10,7 +10,10 @@
 package net.sf.jsqlparser.expression;
 
 import net.sf.jsqlparser.JSQLParserException;
+import net.sf.jsqlparser.expression.operators.arithmetic.Addition;
+import net.sf.jsqlparser.schema.Column;
 import net.sf.jsqlparser.statement.select.PlainSelect;
+import net.sf.jsqlparser.statement.update.Update;
 import net.sf.jsqlparser.test.TestUtils;
 import org.assertj.core.api.Assertions;
 import org.junit.jupiter.api.Test;
@@ -27,4 +30,67 @@ void testParsing() throws JSQLParserException {
         Function f = select.getSelectItem(0).getExpression(Function.class);
         Assertions.assertThat(f.getParameters().get(1)).isInstanceOf(DateUnitExpression.class);
     }
+
+    @Test
+    void testUnitArgumentKeepsItsSpelling() throws JSQLParserException {
+        String sqlStr = "SELECT DATEADD(day, 1, d) FROM t";
+
+        PlainSelect select = (PlainSelect) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr);
+
+        Function f = select.getSelectItem(0).getExpression(Function.class);
+        DateUnitExpression unit = (DateUnitExpression) f.getParameters().get(0);
+        Assertions.assertThat(unit.getType()).isEqualTo(DateUnitExpression.DateUnit.DAY);
+        Assertions.assertThat(unit).hasToString("day");
+    }
+
+    @Test
+    void testUnitWordOutsideFunctionArgumentsIsColumn() throws JSQLParserException {
+        String sqlStr = "SELECT year FROM t";
+
+        PlainSelect select = (PlainSelect) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr);
+
+        Column column = select.getSelectItem(0).getExpression(Column.class);
+        Assertions.assertThat(column.getColumnName()).isEqualTo("year");
+    }
+
+    @Test
+    void testUnitWordAsQualifierIsColumn() throws JSQLParserException {
+        String sqlStr = "SELECT month.amount FROM sales month";
+
+        PlainSelect select = (PlainSelect) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr);
+
+        Column column = select.getSelectItem(0).getExpression(Column.class);
+        Assertions.assertThat(column.getFullyQualifiedName()).isEqualTo("month.amount");
+    }
+
+    @Test
+    void testUnitWordWithinArgumentExpressionIsColumn() throws JSQLParserException {
+        String sqlStr = "SELECT COALESCE(year + 1, 0) FROM t";
+
+        PlainSelect select = (PlainSelect) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr);
+
+        Function f = select.getSelectItem(0).getExpression(Function.class);
+        Addition addition = (Addition) f.getParameters().get(0);
+        Assertions.assertThat(addition.getLeftExpression()).isInstanceOf(Column.class);
+    }
+
+    @Test
+    void testQuotedUnitWordArgumentIsColumn() throws JSQLParserException {
+        String sqlStr = "SELECT DATEADD(\"day\", 1, d) FROM t";
+
+        PlainSelect select = (PlainSelect) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr);
+
+        Function f = select.getSelectItem(0).getExpression(Function.class);
+        Assertions.assertThat(f.getParameters().get(0)).isInstanceOf(Column.class);
+    }
+
+    @Test
+    void testUnitWordInUpdateSetTupleIsColumn() throws JSQLParserException {
+        String sqlStr = "UPDATE t SET (a, year) = (1, 2)";
+
+        Update update = (Update) TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr);
+
+        Assertions.assertThat(update.getUpdateSets().get(0).getColumn(1).getColumnName())
+                .isEqualTo("year");
+    }
 }