[SPARK-13698] Fix Analysis Exceptions when Using Backticks in Generate

Author: dilipbiswal

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/CatalystQl.scala

@@ -999,10 +999,16 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
     }
 
     val attributes = clauses.collect {
-      case Token(a, Nil) => UnresolvedAttribute(a.toLowerCase)
+      case Token(a, Nil) => UnresolvedAttribute(cleanIdentifier(a.toLowerCase))
     }
 
-    Generate(generator, join = true, outer = outer, Some(alias.toLowerCase), attributes, child)
+    Generate(
+      generator,
+      join = true,
+      outer = outer,
+      Some(cleanIdentifier(alias.toLowerCase)),
+      attributes,
+      child)
   }
 
   protected def nodeToGenerator(node: ASTNode): Generator = noParseRule("Generator", node)

sql/hive/src/test/scala/org/apache/spark/sql/hive/HiveQlSuite.scala

@@ -208,4 +208,13 @@ class HiveQlSuite extends SparkFunSuite with BeforeAndAfterAll {
         |USING 'cat' AS (`thing1` int, `thing2` string) FROM `default`.`parquet_t1`) AS t
       """.stripMargin)
   }
+
+  test("use backticks in output of Generator") {
+    val plan = parser.parsePlan(
+      """SELECT `gentab2`.`gencol2`
+        |FROM `default`.`src`
+        |LATERAL VIEW explode(array(array(1, 2, 3))) `gentab1` AS `gencol1`
+        |LATERAL VIEW explode(`gentab1`.`gencol1`) `gentab2` AS `gencol2`
+      """.stripMargin)
+  }
 }

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala

@@ -254,6 +254,14 @@ class SQLQuerySuite extends QueryTest with SQLTestUtils with TestHiveSingleton {
     checkAnswer(
       sql("SELECT ints FROM nestedArray LATERAL VIEW explode(a.b) a AS ints"),
       Row(1) :: Row(2) :: Row(3) :: Nil)
+
+    checkAnswer(
+      sql("SELECT `ints` FROM nestedArray LATERAL VIEW explode(a.b) `a` AS `ints`"),
+      Row(1) :: Row(2) :: Row(3) :: Nil)
+
+    checkAnswer(
+      sql("SELECT `a`.`ints` FROM nestedArray LATERAL VIEW explode(a.b) `a` AS `ints`"),
+      Row(1) :: Row(2) :: Row(3) :: Nil)
   }
 
   test("SPARK-4512 Fix attribute reference resolution error when using SORT BY") {