fix fe of regr_slope and add test_regr_slope.groovy

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/functions/agg/RegrSlope.java

@@ -20,8 +20,8 @@
 import org.apache.doris.catalog.FunctionSignature;
 import org.apache.doris.nereids.exceptions.AnalysisException;
 import org.apache.doris.nereids.trees.expressions.Expression;
+import org.apache.doris.nereids.trees.expressions.functions.AlwaysNullable;
 import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
-import org.apache.doris.nereids.trees.expressions.functions.window.SupportWindowAnalytic;
 import org.apache.doris.nereids.trees.expressions.shape.BinaryExpression;
 import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
 import org.apache.doris.nereids.types.BigIntType;
@@ -40,9 +40,8 @@
 /**
  * AggregateFunction 'regr_slope'.
  */
-
-public class RegrSlope extends NullableAggregateFunction
-        implements BinaryExpression, ExplicitlyCastableSignature, SupportWindowAnalytic {
+public class RegrSlope extends AggregateFunction
+        implements BinaryExpression, ExplicitlyCastableSignature, AlwaysNullable {
 
     public static final List<FunctionSignature> SIGNATURES = ImmutableList.of(
             FunctionSignature.ret(DoubleType.INSTANCE).args(DoubleType.INSTANCE, DoubleType.INSTANCE),
@@ -57,18 +56,14 @@ public class RegrSlope extends NullableAggregateFunction
      * Constructor with 2 arguments.
      */
     public RegrSlope(Expression arg1, Expression arg2) {
-        this(false, true, arg1, arg2);
+        this(false, arg1, arg2);
     }
 
     /**
      * Constructor with distinct flag and 2 arguments.
      */
     public RegrSlope(boolean distinct, Expression arg1, Expression arg2) {
-        this(distinct, true, arg1, arg2);
-    }
-
-    public RegrSlope(boolean distinct, boolean alwaysNullable, Expression arg1, Expression arg2) {
-        super("regr_slope", distinct, alwaysNullable, arg1, arg2);
+        super("regr_slope", distinct, arg1, arg2);
     }
 
     @Override
@@ -87,17 +82,12 @@ public void checkLegalityBeforeTypeCoercion() throws AnalysisException {
     @Override
     public RegrSlope withDistinctAndChildren(boolean distinct, List<Expression> children) {
         Preconditions.checkArgument(children.size() == 2);
-        return new RegrSlope(distinct, alwaysNullable, children.get(0), children.get(1));
-    }
-
-    @Override
-    public NullableAggregateFunction withAlwaysNullable(boolean alwaysNullable) {
-        return new RegrSlope(distinct, alwaysNullable, children().get(0), children().get(1));
+        return new RegrSlope(distinct, children.get(0), children.get(1));
     }
 
     @Override
     public <R, C> R accept(ExpressionVisitor<R, C> visitor, C context) {
-        return visitor.visitNullableAggregateFunction(this, context);
+        return visitor.visitRegrSlope(this, context);
     }
 
     @Override

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

@@ -273,7 +273,7 @@ default R visitRegrIntercept(RegrIntercept regrIntercept, C context) {
     }
 
     default R visitRegrSlope(RegrSlope regrSlope, C context) {
-        return visitNullableAggregateFunction(regrSlope, context);
+        return visitAggregateFunction(regrSlope, context);
     }
 
     default R visitRetention(Retention retention, C context) {

regression-test/data/query_p0/aggregate/test_regr_slope.out

@@ -0,0 +1,114 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !sql_empty_1 --
+\N
+
+-- !sql_empty_2 --
+
+-- !sql_int_1 --
+0.0
+
+-- !sql_int_2 --
+\N
+
+-- !sql_int_3 --
+0.6853448275862069
+
+-- !sql_int_4 --
+0.6853448275862069
+
+-- !sql_int_5 --
+0.6853448275862069
+
+-- !sql_int_6 --
+0.0
+
+-- !sql_int_7 --
+\N
+
+-- !sql_int_8 --
+0.7390029325513197
+
+-- !sql_int_8 --
+\N
+\N
+9.0
+\N
+\N
+
+-- !sql_int_9 --
+0.7401574803149606
+
+-- !sql_int_9 --
+9.0
+\N
+\N
+
+-- !sql_int_10 --
+0.7401574803149606
+
+-- !sql_int_10 --
+9.0
+\N
+\N
+
+-- !sql_double_1 --
+0.0
+
+-- !sql_double_2 --
+\N
+
+-- !sql_double_3 --
+0.6987176230207431
+
+-- !sql_double_3 --
+\N
+\N
+\N
+\N
+\N
+
+-- !sql_double_4 --
+0.6987176230207446
+
+-- !sql_double_4 --
+\N
+\N
+\N
+\N
+\N
+
+-- !sql_double_5 --
+0.6987176230207446
+
+-- !sql_double_6 --
+0.0
+
+-- !sql_double_7 --
+\N
+
+-- !sql_double_8 --
+0.7390029325513197
+
+-- !sql_double_8 --
+\N
+\N
+9.0
+\N
+\N
+
+-- !sql_double_9 --
+0.7401574803149606
+
+-- !sql_double_9 --
+9.0
+\N
+\N
+
+-- !sql_double_10 --
+0.7401574803149606
+
+-- !sql_double_10 --
+9.0
+\N
+\N
+