[CALCITE-6147] CAST(CAST(EMPNO AS VARCHAR) AS INT) should be simplifi…

…ed to EMPNO

Close apache#3555

core/src/main/java/org/apache/calcite/rex/RexUtil.java

@@ -72,6 +72,8 @@
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
 
+import static org.apache.calcite.rel.type.RelDataType.PRECISION_NOT_SPECIFIED;
+
 import static java.util.Objects.requireNonNull;
 
 /**
@@ -1697,7 +1699,8 @@ public static boolean isLosslessCast(RelDataType source, RelDataType target) {
       if (source.getScale() != -1 && source.getScale() != 0) {
         sourceLength += source.getScale() + 1; // include decimal mark
       }
-      return target.getPrecision() >= sourceLength;
+      final int targetPrecision = target.getPrecision();
+      return targetPrecision == PRECISION_NOT_SPECIFIED || targetPrecision >= sourceLength;
     }
     // Return FALSE by default
     return false;

core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java

@@ -2130,7 +2130,7 @@ private SqlDialect nonOrdinalDialect() {
   @Test void testHiveCastAsInt() {
     String query = "select cast( cast(\"employee_id\" as varchar) as int) "
         + "from \"foodmart\".\"reserve_employee\" ";
-    final String expected = "SELECT CAST(CAST(employee_id AS VARCHAR) AS INT)\n"
+    final String expected = "SELECT employee_id\n"
         + "FROM foodmart.reserve_employee";
     sql(query).withHive().ok(expected);
   }
@@ -2151,17 +2151,17 @@ private SqlDialect nonOrdinalDialect() {
             + "cast(cast(\"employee_id\" as varchar) as time), "
             + "cast(cast(\"employee_id\" as varchar) as boolean) "
             + "from \"foodmart\".\"reserve_employee\" ";
-    final String expected = "SELECT CAST(CAST(employee_id AS STRING) AS INT64), "
-            + "CAST(CAST(employee_id AS STRING) AS INT64), "
-            + "CAST(CAST(employee_id AS STRING) AS INT64), "
-            + "CAST(CAST(employee_id AS STRING) AS INT64), "
-            + "CAST(CAST(employee_id AS STRING) AS FLOAT64), "
-            + "CAST(CAST(employee_id AS STRING) AS STRING), "
+    final String expected = "SELECT CAST(employee_id AS INT64), "
+            + "CAST(employee_id AS INT64), "
+            + "CAST(employee_id AS INT64), "
+            + "employee_id, "
+            + "CAST(employee_id AS FLOAT64), "
+            + "CAST(employee_id AS STRING), "
             + "CAST(CAST(employee_id AS STRING) AS BYTES), "
             + "CAST(CAST(employee_id AS STRING) AS BYTES), "
-            + "CAST(CAST(employee_id AS STRING) AS TIMESTAMP), "
-            + "CAST(CAST(employee_id AS STRING) AS FLOAT64), "
-            + "CAST(CAST(employee_id AS STRING) AS NUMERIC), "
+            + "CAST(employee_id AS TIMESTAMP), "
+            + "CAST(employee_id AS FLOAT64), "
+            + "CAST(employee_id AS NUMERIC), "
             + "CAST(CAST(employee_id AS STRING) AS DATE), "
             + "CAST(CAST(employee_id AS STRING) AS TIME), "
             + "CAST(CAST(employee_id AS STRING) AS BOOL)\n"

core/src/test/java/org/apache/calcite/rex/RexLosslessCastTest.java

@@ -40,6 +40,7 @@ class RexLosslessCastTest extends RexProgramTestBase {
     final RelDataType charType6 = typeFactory.createSqlType(SqlTypeName.CHAR, 6);
     final RelDataType varCharType10 = typeFactory.createSqlType(SqlTypeName.VARCHAR, 10);
     final RelDataType varCharType11 = typeFactory.createSqlType(SqlTypeName.VARCHAR, 11);
+    final RelDataType varcharType = typeFactory.createSqlType(SqlTypeName.VARCHAR);
 
     // Negative
     assertThat(RexUtil.isLosslessCast(rexBuilder.makeInputRef(intType, 0)), is(false));
@@ -125,6 +126,10 @@ class RexLosslessCastTest extends RexProgramTestBase {
         RexUtil.isLosslessCast(
             rexBuilder.makeCast(
                 varCharType11, rexBuilder.makeInputRef(varCharType10, 0))), is(true));
+    assertThat(
+        RexUtil.isLosslessCast(
+            rexBuilder.makeCast(
+                varcharType, rexBuilder.makeInputRef(intType, 0))), is(true));
   }
 
   @Test void removeRedundantCast() {
@@ -151,6 +156,7 @@ class RexLosslessCastTest extends RexProgramTestBase {
     checkSimplify(
         cast(cast(cast(core, tInt()), tBigInt()), tInt()),
         "?0.notNullInt0");
+    checkSimplify(cast(cast(vInt(), tVarchar()), tInt()), "CAST(?0.int0):INTEGER NOT NULL");
   }
 
   @Test void removeLosslesssCastChar() {