[SPARK-7952][SPARK-7984][SQL] equality check between boolean type and numeric type is broken.

The origin code has several problems:
* `true <=> 1` will return false as we didn't set a rule to handle it.
* `true = a` where `a` is not `Literal` and its value is 1, will return false as we only handle literal values.

Author: Wenchen Fan <cloud0fan@outlook.com>

Closes #6505 from cloud-fan/tmp1 and squashes the following commits:

77f0f39 [Wenchen Fan] minor fix
b6401ba [Wenchen Fan] add type coercion for CaseKeyWhen and address comments
ebc8c61 [Wenchen Fan] use SQLTestUtils and If
625973c [Wenchen Fan] improve
9ba2130 [Wenchen Fan] address comments
fc0d741 [Wenchen Fan] fix style
2846a04 [Wenchen Fan] fix 7952

5 files changed, 158 insertions, 47 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
index 96d7b96e60..edcc918bfe 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercion.scala
@@ -76,7 +76,7 @@ trait HiveTypeCoercion {
     WidenTypes ::
     PromoteStrings ::
     DecimalPrecision ::
-    BooleanComparisons ::
+    BooleanEqualization ::
     StringToIntegralCasts ::
     FunctionArgumentConversion ::
     CaseWhenCoercion ::
@@ -119,7 +119,7 @@ trait HiveTypeCoercion {
    * the appropriate numeric equivalent.
    */
   object ConvertNaNs extends Rule[LogicalPlan] {
-    val stringNaN = Literal("NaN")
+    private val stringNaN = Literal("NaN")
 
     def apply(plan: LogicalPlan): LogicalPlan = plan transform {
       case q: LogicalPlan => q transformExpressions {
@@ -349,17 +349,17 @@ trait HiveTypeCoercion {
     import scala.math.{max, min}
 
     // Conversion rules for integer types into fixed-precision decimals
-    val intTypeToFixed: Map[DataType, DecimalType] = Map(
+    private val intTypeToFixed: Map[DataType, DecimalType] = Map(
       ByteType -> DecimalType(3, 0),
       ShortType -> DecimalType(5, 0),
       IntegerType -> DecimalType(10, 0),
       LongType -> DecimalType(20, 0)
     )
 
-    def isFloat(t: DataType): Boolean = t == FloatType || t == DoubleType
+    private def isFloat(t: DataType): Boolean = t == FloatType || t == DoubleType
 
     // Conversion rules for float and double into fixed-precision decimals
-    val floatTypeToFixed: Map[DataType, DecimalType] = Map(
+    private val floatTypeToFixed: Map[DataType, DecimalType] = Map(
       FloatType -> DecimalType(7, 7),
       DoubleType -> DecimalType(15, 15)
     )
@@ -482,30 +482,66 @@ trait HiveTypeCoercion {
   }
 
   /**
-   * Changes Boolean values to Bytes so that expressions like true < false can be Evaluated.
+   * Changes numeric values to booleans so that expressions like true = 1 can be evaluated.
    */
-  object BooleanComparisons extends Rule[LogicalPlan] {
-    val trueValues = Seq(1, 1L, 1.toByte, 1.toShort, new java.math.BigDecimal(1)).map(Literal(_))
-    val falseValues = Seq(0, 0L, 0.toByte, 0.toShort, new java.math.BigDecimal(0)).map(Literal(_))
+  object BooleanEqualization extends Rule[LogicalPlan] {
+    private val trueValues = Seq(1.toByte, 1.toShort, 1, 1L, new java.math.BigDecimal(1))
+    private val falseValues = Seq(0.toByte, 0.toShort, 0, 0L, new java.math.BigDecimal(0))
+
+    private def buildCaseKeyWhen(booleanExpr: Expression, numericExpr: Expression) = {
+      CaseKeyWhen(numericExpr, Seq(
+        Literal(trueValues.head), booleanExpr,
+        Literal(falseValues.head), Not(booleanExpr),
+        Literal(false)))
+    }
+
+    private def transform(booleanExpr: Expression, numericExpr: Expression) = {
+      If(Or(IsNull(booleanExpr), IsNull(numericExpr)),
+        Literal.create(null, BooleanType),
+        buildCaseKeyWhen(booleanExpr, numericExpr))
+    }
+
+    private def transformNullSafe(booleanExpr: Expression, numericExpr: Expression) = {
+      CaseWhen(Seq(
+        And(IsNull(booleanExpr), IsNull(numericExpr)), Literal(true),
+        Or(IsNull(booleanExpr), IsNull(numericExpr)), Literal(false),
+        buildCaseKeyWhen(booleanExpr, numericExpr)
+      ))
+    }
 
     def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
       // Skip nodes who's children have not been resolved yet.
       case e if !e.childrenResolved => e
 
-      // Hive treats (true = 1) as true and (false = 0) as true.
-      case EqualTo(l @ BooleanType(), r) if trueValues.contains(r) => l
-      case EqualTo(l, r @ BooleanType()) if trueValues.contains(l) => r
-      case EqualTo(l @ BooleanType(), r) if falseValues.contains(r) => Not(l)
-      case EqualTo(l, r @ BooleanType()) if falseValues.contains(l) => Not(r)
-
-      // No need to change other EqualTo operators as that actually makes sense for boolean types.
-      case e: EqualTo => e
-      // No need to change the EqualNullSafe operators, too
-      case e: EqualNullSafe => e
-      // Otherwise turn them to Byte types so that there exists and ordering.
-      case p: BinaryComparison if p.left.dataType == BooleanType &&
-                                  p.right.dataType == BooleanType =>
-        p.makeCopy(Array(Cast(p.left, ByteType), Cast(p.right, ByteType)))
+      // Hive treats (true = 1) as true and (false = 0) as true,
+      // all other cases are considered as false.
+
+      // We may simplify the expression if one side is literal numeric values
+      case EqualTo(l @ BooleanType(), Literal(value, _: NumericType))
+        if trueValues.contains(value) => l
+      case EqualTo(l @ BooleanType(), Literal(value, _: NumericType))
+        if falseValues.contains(value) => Not(l)
+      case EqualTo(Literal(value, _: NumericType), r @ BooleanType())
+        if trueValues.contains(value) => r
+      case EqualTo(Literal(value, _: NumericType), r @ BooleanType())
+        if falseValues.contains(value) => Not(r)
+      case EqualNullSafe(l @ BooleanType(), Literal(value, _: NumericType))
+        if trueValues.contains(value) => And(IsNotNull(l), l)
+      case EqualNullSafe(l @ BooleanType(), Literal(value, _: NumericType))
+        if falseValues.contains(value) => And(IsNotNull(l), Not(l))
+      case EqualNullSafe(Literal(value, _: NumericType), r @ BooleanType())
+        if trueValues.contains(value) => And(IsNotNull(r), r)
+      case EqualNullSafe(Literal(value, _: NumericType), r @ BooleanType())
+        if falseValues.contains(value) => And(IsNotNull(r), Not(r))
+
+      case EqualTo(l @ BooleanType(), r @ NumericType()) =>
+        transform(l , r)
+      case EqualTo(l @ NumericType(), r @ BooleanType()) =>
+        transform(r, l)
+      case EqualNullSafe(l @ BooleanType(), r @ NumericType()) =>
+        transformNullSafe(l, r)
+      case EqualNullSafe(l @ NumericType(), r @ BooleanType()) =>
+        transformNullSafe(r, l)
     }
   }
 
@@ -606,7 +642,7 @@ trait HiveTypeCoercion {
     import HiveTypeCoercion._
 
     def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
-      case cw: CaseWhenLike if !cw.resolved && cw.childrenResolved && !cw.valueTypesEqual =>
+      case cw: CaseWhenLike if cw.childrenResolved && !cw.valueTypesEqual =>
         logDebug(s"Input values for null casting ${cw.valueTypes.mkString(",")}")
         val commonType = cw.valueTypes.reduce { (v1, v2) =>
           findTightestCommonType(v1, v2).getOrElse(sys.error(
@@ -625,6 +661,23 @@ trait HiveTypeCoercion {
           case CaseKeyWhen(key, _) =>
             CaseKeyWhen(key, transformedBranches)
         }
+
+      case ckw: CaseKeyWhen if ckw.childrenResolved && !ckw.resolved =>
+        val commonType = (ckw.key +: ckw.whenList).map(_.dataType).reduce { (v1, v2) =>
+          findTightestCommonType(v1, v2).getOrElse(sys.error(
+            s"Types in CASE WHEN must be the same or coercible to a common type: $v1 != $v2"))
+        }
+        val transformedBranches = ckw.branches.sliding(2, 2).map {
+          case Seq(when, then) if when.dataType != commonType =>
+            Seq(Cast(when, commonType), then)
+          case s => s
+        }.reduce(_ ++ _)
+        val transformedKey = if (ckw.key.dataType != commonType) {
+          Cast(ckw.key, commonType)
+        } else {
+          ckw.key
+        }
+        CaseKeyWhen(transformedKey, transformedBranches)
     }
   }
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
index e2d1c8115e..4f422d69c4 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
@@ -366,7 +366,7 @@ trait CaseWhenLike extends Expression {
 
   // both then and else val should be considered.
   def valueTypes: Seq[DataType] = (thenList ++ elseValue).map(_.dataType)
-  def valueTypesEqual: Boolean = valueTypes.distinct.size <= 1
+  def valueTypesEqual: Boolean = valueTypes.distinct.size == 1
 
   override def dataType: DataType = {
     if (!resolved) {
@@ -442,7 +442,8 @@ case class CaseKeyWhen(key: Expression, branches: Seq[Expression]) extends CaseW
   override def children: Seq[Expression] = key +: branches
 
   override lazy val resolved: Boolean =
-    childrenResolved && valueTypesEqual
+    childrenResolved && valueTypesEqual &&
+    (key +: whenList).map(_.dataType).distinct.size == 1
 
   /** Written in imperative fashion for performance considerations. */
   override def eval(input: Row): Any = {
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala
index f0101f4a88..a0798428db 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/HiveTypeCoercionSuite.scala
@@ -20,7 +20,8 @@ package org.apache.spark.sql.catalyst.analysis
 import org.apache.spark.sql.catalyst.plans.PlanTest
 
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.catalyst.plans.logical.{LocalRelation, Project}
+import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, LocalRelation, Project}
+import org.apache.spark.sql.catalyst.rules.Rule
 import org.apache.spark.sql.types._
 
 class HiveTypeCoercionSuite extends PlanTest {
@@ -104,15 +105,16 @@ class HiveTypeCoercionSuite extends PlanTest {
     widenTest(ArrayType(IntegerType), StructType(Seq()), None)
   }
 
+  private def ruleTest(rule: Rule[LogicalPlan], initial: Expression, transformed: Expression) {
+    val testRelation = LocalRelation(AttributeReference("a", IntegerType)())
+    comparePlans(
+      rule(Project(Seq(Alias(initial, "a")()), testRelation)),
+      Project(Seq(Alias(transformed, "a")()), testRelation))
+  }
+
   test("coalesce casts") {
     val fac = new HiveTypeCoercion { }.FunctionArgumentConversion
-    def ruleTest(initial: Expression, transformed: Expression) {
-      val testRelation = LocalRelation(AttributeReference("a", IntegerType)())
-      comparePlans(
-        fac(Project(Seq(Alias(initial, "a")()), testRelation)),
-        Project(Seq(Alias(transformed, "a")()), testRelation))
-    }
-    ruleTest(
+    ruleTest(fac,
       Coalesce(Literal(1.0)
         :: Literal(1)
         :: Literal.create(1.0, FloatType)
@@ -121,7 +123,7 @@ class HiveTypeCoercionSuite extends PlanTest {
         :: Cast(Literal(1), DoubleType)
         :: Cast(Literal.create(1.0, FloatType), DoubleType)
         :: Nil))
-    ruleTest(
+    ruleTest(fac,
       Coalesce(Literal(1L)
         :: Literal(1)
         :: Literal(new java.math.BigDecimal("1000000000000000000000"))
@@ -131,4 +133,39 @@ class HiveTypeCoercionSuite extends PlanTest {
         :: Cast(Literal(new java.math.BigDecimal("1000000000000000000000")), DecimalType())
         :: Nil))
   }
+
+  test("type coercion for CaseKeyWhen") {
+    val cwc = new HiveTypeCoercion {}.CaseWhenCoercion
+    ruleTest(cwc,
+      CaseKeyWhen(Literal(1.toShort), Seq(Literal(1), Literal("a"))),
+      CaseKeyWhen(Cast(Literal(1.toShort), IntegerType), Seq(Literal(1), Literal("a")))
+    )
+    // Will remove exception expectation in PR#6405
+    intercept[RuntimeException] {
+      ruleTest(cwc,
+        CaseKeyWhen(Literal(true), Seq(Literal(1), Literal("a"))),
+        CaseKeyWhen(Literal(true), Seq(Literal(1), Literal("a")))
+      )
+    }
+  }
+
+  test("type coercion simplification for equal to") {
+    val be = new HiveTypeCoercion {}.BooleanEqualization
+    ruleTest(be,
+      EqualTo(Literal(true), Literal(1)),
+      Literal(true)
+    )
+    ruleTest(be,
+      EqualTo(Literal(true), Literal(0)),
+      Not(Literal(true))
+    )
+    ruleTest(be,
+      EqualNullSafe(Literal(true), Literal(1)),
+      And(IsNotNull(Literal(true)), Literal(true))
+    )
+    ruleTest(be,
+      EqualNullSafe(Literal(true), Literal(0)),
+      And(IsNotNull(Literal(true)), Not(Literal(true)))
+    )
+  }
 }
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
index 3f5a660f17..b6927485f4 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionEvaluationSuite.scala
@@ -862,7 +862,7 @@ class ExpressionEvaluationSuite extends ExpressionEvaluationBaseSuite {
     val c5 = 'a.string.at(4)
     val c6 = 'a.string.at(5)
 
-    val literalNull = Literal.create(null, BooleanType)
+    val literalNull = Literal.create(null, IntegerType)
     val literalInt = Literal(1)
     val literalString = Literal("a")
 
@@ -871,12 +871,12 @@ class ExpressionEvaluationSuite extends ExpressionEvaluationBaseSuite {
     checkEvaluation(CaseKeyWhen(c2, Seq(literalInt, c4, c5)), "a", row)
     checkEvaluation(CaseKeyWhen(c2, Seq(c1, c4, c5)), "b", row)
     checkEvaluation(CaseKeyWhen(c4, Seq(literalString, c2, c3)), 1, row)
-    checkEvaluation(CaseKeyWhen(c4, Seq(c1, c3, c5, c2, Literal(3))), 3, row)
+    checkEvaluation(CaseKeyWhen(c4, Seq(c6, c3, c5, c2, Literal(3))), 3, row)
 
     checkEvaluation(CaseKeyWhen(literalInt, Seq(c2, c4, c5)), "a", row)
     checkEvaluation(CaseKeyWhen(literalString, Seq(c5, c2, c4, c3)), 2, row)
-    checkEvaluation(CaseKeyWhen(literalInt, Seq(c5, c2, c4, c3)), null, row)
-    checkEvaluation(CaseKeyWhen(literalNull, Seq(c5, c2, c1, c3)), 2, row)
+    checkEvaluation(CaseKeyWhen(c6, Seq(c5, c2, c4, c3)), null, row)
+    checkEvaluation(CaseKeyWhen(literalNull, Seq(c2, c5, c1, c6)), "c", row)
   }
 
   test("complex type") {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
index bf18bf854a..63f7d314fb 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
@@ -24,7 +24,7 @@ import org.apache.spark.sql.catalyst.errors.DialectException
 import org.apache.spark.sql.execution.GeneratedAggregate
 import org.apache.spark.sql.functions._
 import org.apache.spark.sql.TestData._
-import org.apache.spark.sql.test.TestSQLContext
+import org.apache.spark.sql.test.{SQLTestUtils, TestSQLContext}
 import org.apache.spark.sql.test.TestSQLContext.{udf => _, _}
 
 import org.apache.spark.sql.types._
@@ -32,12 +32,12 @@ import org.apache.spark.sql.types._
 /** A SQL Dialect for testing purpose, and it can not be nested type */
 class MyDialect extends DefaultParserDialect
 
-class SQLQuerySuite extends QueryTest with BeforeAndAfterAll {
+class SQLQuerySuite extends QueryTest with BeforeAndAfterAll with SQLTestUtils {
   // Make sure the tables are loaded.
   TestData
 
-  import org.apache.spark.sql.test.TestSQLContext.implicits._
-  val sqlCtx = TestSQLContext
+  val sqlContext = TestSQLContext
+  import sqlContext.implicits._
 
   test("SPARK-6743: no columns from cache") {
     Seq(
@@ -915,7 +915,7 @@ class SQLQuerySuite extends QueryTest with BeforeAndAfterAll {
       Row(values(0).toInt, values(1), values(2).toBoolean, v4)
     }
 
-    val df1 = sqlCtx.createDataFrame(rowRDD1, schema1)
+    val df1 = createDataFrame(rowRDD1, schema1)
     df1.registerTempTable("applySchema1")
     checkAnswer(
       sql("SELECT * FROM applySchema1"),
@@ -945,7 +945,7 @@ class SQLQuerySuite extends QueryTest with BeforeAndAfterAll {
       Row(Row(values(0).toInt, values(2).toBoolean), Map(values(1) -> v4))
     }
 
-    val df2 = sqlCtx.createDataFrame(rowRDD2, schema2)
+    val df2 = createDataFrame(rowRDD2, schema2)
     df2.registerTempTable("applySchema2")
     checkAnswer(
       sql("SELECT * FROM applySchema2"),
@@ -970,7 +970,7 @@ class SQLQuerySuite extends QueryTest with BeforeAndAfterAll {
       Row(Row(values(0).toInt, values(2).toBoolean), scala.collection.mutable.Map(values(1) -> v4))
     }
 
-    val df3 = sqlCtx.createDataFrame(rowRDD3, schema2)
+    val df3 = createDataFrame(rowRDD3, schema2)
     df3.registerTempTable("applySchema3")
 
     checkAnswer(
@@ -1015,7 +1015,7 @@ class SQLQuerySuite extends QueryTest with BeforeAndAfterAll {
       .build()
     val schemaWithMeta = new StructType(Array(
       schema("id"), schema("name").copy(metadata = metadata), schema("age")))
-    val personWithMeta = sqlCtx.createDataFrame(person.rdd, schemaWithMeta)
+    val personWithMeta = createDataFrame(person.rdd, schemaWithMeta)
     def validateMetadata(rdd: DataFrame): Unit = {
       assert(rdd.schema("name").metadata.getString(docKey) == docValue)
     }
@@ -1331,4 +1331,24 @@ class SQLQuerySuite extends QueryTest with BeforeAndAfterAll {
 
     checkAnswer(sql("SELECT a.`c.b`, `b.$q`[0].`a@!.q`, `q.w`.`w.i&`[0] FROM t"), Row(1, 1, 1))
   }
+
+  test("SPARK-7952: fix the equality check between boolean and numeric types") {
+    withTempTable("t") {
+      // numeric field i, boolean field j, result of i = j, result of i <=> j
+      Seq[(Integer, java.lang.Boolean, java.lang.Boolean, java.lang.Boolean)](
+        (1, true, true, true),
+        (0, false, true, true),
+        (2, true, false, false),
+        (2, false, false, false),
+        (null, true, null, false),
+        (null, false, null, false),
+        (0, null, null, false),
+        (1, null, null, false),
+        (null, null, null, true)
+      ).toDF("i", "b", "r1", "r2").registerTempTable("t")
+
+      checkAnswer(sql("select i = b from t"), sql("select r1 from t"))
+      checkAnswer(sql("select i <=> b from t"), sql("select r2 from t"))
+    }
+  }
 }