[SPARK-2041][SQL] Correctly analyze queries where columnName == tableName.

Author: Michael Armbrust <michael@databricks.com>

Closes #985 from marmbrus/tableName and squashes the following commits:

3caaa27 [Michael Armbrust] Correctly analyze queries where columnName == tableName.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala

@@ -64,7 +64,8 @@ abstract class LogicalPlan extends QueryPlan[LogicalPlan] {
     // struct fields.
     val options = children.flatMap(_.output).flatMap { option =>
       // If the first part of the desired name matches a qualifier for this possible match, drop it.
-      val remainingParts = if (option.qualifiers contains parts.head) parts.drop(1) else parts
+      val remainingParts =
+        if (option.qualifiers.contains(parts.head) && parts.size > 1) parts.drop(1) else parts
       if (option.name == remainingParts.head) (option, remainingParts.tail.toList) :: Nil else Nil
     }
 

sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala

@@ -28,6 +28,12 @@ class SQLQuerySuite extends QueryTest {
   // Make sure the tables are loaded.
   TestData
 
+  test("SPARK-2041 column name equals tablename") {
+    checkAnswer(
+      sql("SELECT tableName FROM tableName"),
+      "test")
+  }
+
   test("index into array") {
     checkAnswer(
       sql("SELECT data, data[0], data[0] + data[1], data[0 + 1] FROM arrayData"),

sql/core/src/test/scala/org/apache/spark/sql/TestData.scala

@@ -114,4 +114,7 @@ object TestData {
       NullStrings(2, "ABC") ::
       NullStrings(3, null) :: Nil)
   nullStrings.registerAsTable("nullStrings")
+
+  case class TableName(tableName: String)
+  TestSQLContext.sparkContext.parallelize(TableName("test") :: Nil).registerAsTable("tableName")
 }