[GitHub] [flink] wuchong commented on a change in pull request #8730: [FLINK-12834][table-planner-blink] Support CharType and BinaryType

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wuchong commented on a change in pull request #8730: [FLINK-12834][table-planner-blink] Support CharType and BinaryType
URL: https://github.com/apache/flink/pull/8730#discussion_r296087336
 
 

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 File path: flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/typeutils/TypeCoercion.scala
 ##########
 @@ -63,13 +64,14 @@ object TypeCoercion {
     */
   def canSafelyCast(
       from: LogicalType, to: LogicalType): Boolean = (from.getTypeRoot, to.getTypeRoot) match {
-    case (_, VARCHAR) => true
+    case (_, VARCHAR | CHAR) => true
 
     case (_, DECIMAL) if isNumeric(from) => true
 
-    case (_, _) if numericWideningPrecedence.contains(from) &&
-        numericWideningPrecedence.contains(to) =>
-      if (numericWideningPrecedence.indexOf(from) < numericWideningPrecedence.indexOf(to)) {
+    case (_, _) if numericWideningPrecedence.contains(from.copy(true)) &&
+        numericWideningPrecedence.contains(to.copy(true)) =>
+      if (numericWideningPrecedence.indexOf(from.copy(true)) <
+          numericWideningPrecedence.indexOf(to.copy(true))) {
 
 Review comment:
   What about add both NULLABLE and NOT NULL types to `numericWideningPrecedence`, so that we can avoid the verbose ` xx.copy(true)` in the code.

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