[SPARK-17429][SQL] use ImplicitCastInputTypes with function Length

## What changes were proposed in this pull request?
select length(11);
select length(2.0);
these sql will return errors, but hive is ok.
this PR will support casting input types implicitly for function length
the correct result is:
select length(11) return 2
select length(2.0) return 3

Author: 岑玉海 <261810726@qq.com>
Author: cenyuhai <cenyuhai@didichuxing.com>

Closes #15014 from cenyuhai/SPARK-17429.

1 files changed, 6 insertions, 4 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
index 1cc77464b9..bcc2351049 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
@@ -330,7 +330,8 @@ class StringFunctionsSuite extends QueryTest with SharedSQLContext {
   }
 
   test("string / binary length function") {
-    val df = Seq(("123", Array[Byte](1, 2, 3, 4), 123)).toDF("a", "b", "c")
+    val df = Seq(("123", Array[Byte](1, 2, 3, 4), 123, 2.0f, 3.015))
+      .toDF("a", "b", "c", "d", "e")
     checkAnswer(
       df.select(length($"a"), length($"b")),
       Row(3, 4))
@@ -339,9 +340,10 @@ class StringFunctionsSuite extends QueryTest with SharedSQLContext {
       df.selectExpr("length(a)", "length(b)"),
       Row(3, 4))
 
-    intercept[AnalysisException] {
-      df.selectExpr("length(c)") // int type of the argument is unacceptable
-    }
+    checkAnswer(
+      df.selectExpr("length(c)", "length(d)", "length(e)"),
+      Row(3, 3, 5)
+    )
   }
 
   test("initcap function") {