Add ANSI type coercion

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/AnsiTypeCoercion.scala

@@ -205,6 +205,10 @@ object AnsiTypeCoercion extends TypeCoercionBase {
       case (StringType, AnyTimestampType) =>
         Some(AnyTimestampType.defaultConcreteType)
 
+      // If the StringType has any collation other than UTF8_BINARY, it shouldn't be implicitly
+      // cast to StringType with collation 0.
+      case (st: StringType, StringType) => Some(st)
+
       case (DateType, AnyTimestampType) =>
         Some(AnyTimestampType.defaultConcreteType)