[nereids](datetime) fix wrong result type of datetime add with interval as first arg

fe/fe-core/src/main/java/org/apache/doris/nereids/parser/LogicalPlanBuilder.java

@@ -1334,7 +1334,7 @@ public Expression visitArithmeticBinary(ArithmeticBinaryContext ctx) {
  throw new ParseException("Only supported: " + Operator.ADD, ctx);
  }
  Interval interval = (Interval) left;
- return new TimestampArithmetic(Operator.ADD, right, interval.value(), interval.timeUnit(), true);
+ return new TimestampArithmetic(Operator.ADD, right, interval.value(), interval.timeUnit());
  }
 
  if (right instanceof Interval) {
@@ -1347,7 +1347,7 @@ public Expression visitArithmeticBinary(ArithmeticBinaryContext ctx) {
  throw new ParseException("Only supported: " + Operator.ADD + " and " + Operator.SUBTRACT, ctx);
  }
  Interval interval = (Interval) right;
- return new TimestampArithmetic(op, left, interval.value(), interval.timeUnit(), false);
+ return new TimestampArithmetic(op, left, interval.value(), interval.timeUnit());
  }
 
  return ParserUtils.withOrigin(ctx, () -> {

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/TimestampArithmetic.java

@@ -46,24 +46,21 @@
 public class TimestampArithmetic extends Expression implements BinaryExpression, PropagateNullableOnDateLikeV2Args {
 
  private final String funcName;
- private final boolean intervalFirst;
  private final Operator op;
  private final TimeUnit timeUnit;
 
- public TimestampArithmetic(Operator op, Expression e1, Expression e2, TimeUnit timeUnit, boolean intervalFirst) {
- this(null, op, e1, e2, timeUnit, intervalFirst);
+ public TimestampArithmetic(Operator op, Expression e1, Expression e2, TimeUnit timeUnit) {
+ this(null, op, e1, e2, timeUnit);
  }
 
  /**
  * Full parameter constructor.
  */
- public TimestampArithmetic(String funcName, Operator op, Expression e1, Expression e2, TimeUnit timeUnit,
- boolean intervalFirst) {
+ public TimestampArithmetic(String funcName, Operator op, Expression e1, Expression e2, TimeUnit timeUnit) {
  super(ImmutableList.of(e1, e2));
  Preconditions.checkState(op == Operator.ADD || op == Operator.SUBTRACT);
  this.funcName = funcName;
  this.op = op;
- this.intervalFirst = intervalFirst;
  this.timeUnit = timeUnit;
  }
 
@@ -76,21 +73,16 @@ public <R, C> R accept(ExpressionVisitor<R, C> visitor, C context) {
  public TimestampArithmetic withChildren(List<Expression> children) {
  Preconditions.checkArgument(children.size() == 2);
  return new TimestampArithmetic(this.funcName, this.op, children.get(0), children.get(1),
- this.timeUnit, this.intervalFirst);
+ this.timeUnit);
  }
 
  public Expression withFuncName(String funcName) {
- return new TimestampArithmetic(funcName, this.op, children.get(0), children.get(1), this.timeUnit,
- this.intervalFirst);
+ return new TimestampArithmetic(funcName, this.op, children.get(0), children.get(1), this.timeUnit);
  }
 
  @Override
  public DataType getDataType() throws UnboundException {
- int dateChildIndex = 0;
- if (intervalFirst) {
- dateChildIndex = 1;
- }
- DataType childType = child(dateChildIndex).getDataType();
+ DataType childType = child(0).getDataType();
  if (childType instanceof DateTimeV2Type) {
  return childType;
  }
@@ -149,21 +141,12 @@ public String toSql() {
  strBuilder.append(")");
  return strBuilder.toString();
  }
- if (intervalFirst) {
- // Non-function-call like version with interval as first operand.
- strBuilder.append("INTERVAL ");
- strBuilder.append(child(1).toSql()).append(" ");
- strBuilder.append(timeUnit);
- strBuilder.append(" ").append(op.toString()).append(" ");
- strBuilder.append(child(0).toSql());
- } else {
- // Non-function-call like version with interval as second operand.
- strBuilder.append(child(0).toSql());
- strBuilder.append(" ").append(op.toString()).append(" ");
- strBuilder.append("INTERVAL ");
- strBuilder.append(child(1).toSql()).append(" ");
- strBuilder.append(timeUnit);
- }
+ // Non-function-call like version with interval as second operand.
+ strBuilder.append(child(0).toSql());
+ strBuilder.append(" ").append(op.toString()).append(" ");
+ strBuilder.append("INTERVAL ");
+ strBuilder.append(child(1).toSql()).append(" ");
+ strBuilder.append(timeUnit);
  return strBuilder.toString();
  }
 

fe/fe-core/src/test/java/org/apache/doris/nereids/rules/expression/FoldConstantTest.java

@@ -286,7 +286,7 @@ void testTimestampFold() {
 
  // a + interval 1 day
  Slot a = SlotReference.of("a", DateTimeV2Type.SYSTEM_DEFAULT);
- TimestampArithmetic arithmetic = new TimestampArithmetic(Operator.ADD, a, Literal.of(1), TimeUnit.DAY, false);
+ TimestampArithmetic arithmetic = new TimestampArithmetic(Operator.ADD, a, Literal.of(1), TimeUnit.DAY);
  Expression process = process(arithmetic);
  assertRewrite(process, process);
  }