[fix][libexpr] Fix float/double cast to decimal issue.

Author: nokiaMS

src/expr/calc/casting.cc

@@ -188,14 +188,12 @@ DecimalP Cast(bool v) {
 
 template <>
 DecimalP Cast(float v) {
-  String const f2s = CastFloat(v);
-  return DecimalP(*f2s.GetPtr());
+  return DecimalP(v);
 }
 
 template <>
 DecimalP Cast(double v) {
-  String const d2s = CastDouble(v);
-  return DecimalP(*d2s.GetPtr());
+  return DecimalP(v);
 }
 
 template <>

test/rel/test_rel.cc

@@ -203,20 +203,32 @@ INSTANTIATE_TEST_SUITE_P(
                 new Tuple{nullptr},
             }
         ),
+        /* create table t1(id int, a double, primary key(id);
+         * insert into t1 values(1, 5.8);
+         * select * from t1 where a >= 5.8 and a <= 5.8.
+         * The expected result is null.
+         * It is compatible with mysql and dingodb scenario when making decimal pushdown disable.
+         */
         std::make_tuple(
           "713501F0651603352E3892063501F0651603352E3894065200",
           MakeDataForDoubleToDecimal(),
           Data{
                 //The origin string is longer than range.
-                new Tuple{1, 5.8},
+                nullptr,
             }
         ),
+        /* create table t1(id int, a double, primary key(id);
+         * insert into t1 values(1, 5.8);
+         * select * from t1 where a >= 5.8 and a <= 5.8.
+         * The expected result is null.
+         * It is compatible with mysql and dingodb scenario when making decimal pushdown disable.
+         */
         std::make_tuple(
             "713401F0641603352E3892063401F0641603352E3894065200",
             MakeDataForFloatToDecimal(),
             Data{
               //The origin string is longer than range.
-              new Tuple{1, (float)5.8},
+              nullptr,
             }
         ),
         // PROJECT(input, instr($[1]))

test/types/test_type_decimal.cc

@@ -385,6 +385,10 @@ TEST(TestTypeDecimal, DecimalTest) {
   //Test -dec 0.
   ASSERT_EQ((-Decimal(std::string("0"))).toLong(), 0);
 
+  //Test decimal to double
+  DecimalP dp = DecimalP((double)32.91);
+  ASSERT_EQ(dp.GetPtr()->toString(), std::string("32.9099999999999965894"));
+
   //DecimalP p = DecimalP((float)12.34);
   ASSERT_EQ(DecimalP((long)12).GetPtr()->toString(10,4), std::string("12.0000"));
   ASSERT_EQ(DecimalP((float)12.34).GetPtr()->toString(10,4), std::string("12.3400"));