fix_issue

Author: coderfender

native/spark-expr/src/conversion_funcs/cast.rs

@@ -2354,11 +2354,6 @@ fn parse_string_to_decimal(s: &str, precision: u8, scale: i8) -> SparkResult<Opt
         &format!("DECIMAL({},{})", precision, scale),
     )?;
 
-    //  return early when mantissa is 0
-    if mantissa == 0 {
-        return Ok(Some(0));
-    }
-
     // scale adjustment
     let target_scale = scale as i32;
     let scale_adjustment = target_scale - exponent;

spark/src/test/scala/org/apache/comet/CometCastSuite.scala

@@ -737,7 +737,7 @@ class CometCastSuite extends CometTestBase with AdaptiveSparkPlanHelper {
 
   test("cast StringType to DecimalType(38,10) high precision - check 0 mantissa") {
     withSQLConf(CometConf.getExprAllowIncompatConfigKey(classOf[Cast]) -> "true") {
-      val values = Seq("0e31").toDF("a")
+      val values = Seq("0e31", "000e3375", "0e5887677", "0e40").toDF("a")
       Seq(true, false).foreach(ansiEnabled =>
         castTest(values, DataTypes.createDecimalType(38, 10), testAnsi = ansiEnabled))
     }